Miyaki M, etal., Int J Cancer. 2007 Oct 1;121(7):1627-30. doi: 10.1002/ijc.22829.
Somatic mutations of the PIK3CA gene have recently been detected in various human cancers, including sporadic colorectal cancer. However, mutations of the PIK3CA gene in hereditary colorectal cancers have not been clarified.
To elucidate the mutation status in familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC), which are the most common hereditary colorectal cancers, we investigated PIK3CA mutations in 163 colorectal tumors, including adenomas, intramucosal carcinomas and invasive carcinomas. For comparison, we also analyzed mutations of the same gene in 160 sporadic colorectal tumors at various histopathological stages. Analysis at exons 1, 7, 9 and 20 of the PIK3CA gene revealed somatic mutations in 21% (8 of 39) of FAP invasive carcinomas, 21% (7 of 34) of HNPCC invasive carcinomas, 15% (8 of 52) of sporadic invasive carcinomas, and 14% (7 of 50) of sporadic colorectal metastases in the liver. Mutations in FAP and HNPCC carcinomas predominantly occurred in the kinase domain (exon 20), while the majority of mutations in sporadic cases occurred in the helical domain (exon 9). Adenomas and intramucosal carcinomas from all patients exhibited no mutations (0 of 148). Our data suggest that PIK3CA mutations contribute to the invasion step from intramucosal carcinoma to invasive carcinoma in colorectal carcinogenesis in FAP and HNPCC patients at a similar extent to that seen in sporadic patients.
Limaye N, etal., Am J Hum Genet. 2015 Dec 3;97(6):914-21. doi: 10.1016/j.ajhg.2015.11.011.
Somatic mutations in TEK, the gene encoding endothelial cell tyrosine kinase receptor TIE2, cause more than half of sporadically occurring unifocal venous malformations (VMs). Here, we report that somatic mutations in PIK3CA, the gene encoding the catalytic p110
alpha subunit of PI3K, cause 54% (27 out of 50) of VMs with no detected TEK mutation. The hotspot mutations c.1624G>A, c.1633G>A, and c.3140A>G (p.Glu542Lys, p.Glu545Lys, and p.His1047Arg), frequent in PIK3CA-associated cancers, overgrowth syndromes, and lymphatic malformation (LM), account for >92% of individuals who carry mutations. Like VM-causative mutations in TEK, the PIK3CA mutations cause chronic activation of AKT, dysregulation of certain important angiogenic factors, and abnormal endothelial cell morphology when expressed in human umbilical vein endothelial cells (HUVECs). The p110alpha-specific inhibitor BYL719 restores all abnormal phenotypes tested, in PIK3CA- as well as TEK-mutant HUVECs, demonstrating that they operate via the same pathogenic pathways. Nevertheless, significant genotype-phenotype correlations in lesion localization and histology are observed between individuals with mutations in PIK3CA versus TEK, pointing to gene-specific effects.
Kalinsky K, etal., Clin Cancer Res. 2009 Aug 15;15(16):5049-59. doi: 10.1158/1078-0432.CCR-09-0632. Epub 2009 Aug 11.
PURPOSE: In breast cancer, somatic mutations in the PIK3CA gene are common. The prognostic implication of these activating mutations remains uncertain as moderately sized studies have yielded variable outcomes. Our aim was to determine the prognostic implication
s of PIK3CA mutations in breast cancer. EXPERIMENTAL DESIGN: Archival formalin-fixed paraffin-embedded primary breast tumors, from 590 patients selected for known vital status with a median follow-up of 12.8 years and a tumor >1 cm, were genotyped for PIK3CA mutations. Mutation rates and associations between mutation site and clinicopathologic characteristics were assessed. Progression-free survival, overall survival, and breast cancer-specific survival were examined using Kaplan-Meier or competing risk methodology. RESULTS: PIK3CA mutation is identified in 32.5% of breast cancers. PIK3CA mutation significantly associates with older age at diagnosis, hormone receptor positivity, HER2 negativity, lower tumor grade and stage, and lymph node negativity. Patients with PIK3CA mutated tumors have significant improvement in overall survival (P = 0.03) and breast cancer-specific survival (P = 0.004). Analysis for PIK3CA mutation site-specific associations reveals that the H1047R kinase domain mutation highly associates with node negativity (P = 0.007), whereas helical domain hotspot mutations associate with older age at diagnosis (P = 0.004). CONCLUSION: This study defines the positive prognostic significance of PIK3CA mutations. This work is clinically relevant, as it will significantly affect the design of clinical trials planned for phosphatidylinositol 3-kinase-targeted therapy. Future work may define a population of older age breast cancer patients in whom therapy can be minimized.
Qu L, etal., Biochem Biophys Res Commun. 2016 Feb 5;470(2):306-12. doi: 10.1016/j.bbrc.2016.01.059. Epub 2016 Jan 11.
The atypical protein kinase C isoform PRKC iota (PRKCI) plays a key role in cell proliferation, differentiation, and carcinogenesis, and it has been shown to be a human oncogene. Here, we show that PRKCI overexpression in U2OS cells impaired functional autophagy in normal or cell stress conditions,
as characterized by decreased levels of light chain 3B-II protein (LC3B-II) and weakened degradation of endogenous and exogenous autophagic substrates. Conversely, PRKCI knockdown by small interference RNA resulted in opposite effects. Additionally, we identified two novel PRKCI mutants, PRKCI(L485M) and PRKCI(P560R), which induced autophagy and exhibited dominant negative effects. Further studies indicated that PRKCI knockdown-mediated autophagy was associated with the inactivation of phosphatidylinositol 3-kinase alpha/AKT-mammalian target of rapamycin (PIK3CA/AKT-MTOR) signaling. These data underscore the importance of PRKCI in the regulation of autophagy. Moreover, the finding may be useful in treating PRKCI-overexpressing carcinomas that are characterized by increased levels of autophagy.
Kurek KC, etal., Am J Hum Genet. 2012 Jun 8;90(6):1108-15. doi: 10.1016/j.ajhg.2012.05.006. Epub 2012 May 31.
Congenital lipomatous overgrowth with vascular, epidermal, and skeletal anomalies (CLOVES) is a sporadically occurring, nonhereditary disorder characterized by asymmetric somatic hypertrophy and anomalies in multiple organs. We hypothesized that CLOVES syndrome would be caused by a somatic mutation
arising during early embryonic development. Therefore, we employed massively parallel sequencing to search for somatic mosaic mutations in fresh, frozen, or fixed archival tissue from six affected individuals. We identified mutations in PIK3CA in all six individuals, and mutant allele frequencies ranged from 3% to 30% in affected tissue from multiple embryonic lineages. Interestingly, these same mutations have been identified in cancer cells, in which they increase phosphoinositide-3-kinase activity. We conclude that CLOVES is caused by postzygotic activating mutations in PIK3CA. The application of similar sequencing strategies will probably identify additional genetic causes for sporadically occurring, nonheritable malformations.
Peyre M, etal., N Engl J Med. 2021 Sep 9;385(11):996-1004. doi: 10.1056/NEJMoa2100440.
BACKGROUND: Cerebral cavernous malformations (CCMs) are common sporadic and inherited vascular malformations of the central nervous system. Although familial CCMs are linked to loss-of-function mutations in KRIT1 (CCM1), CCM2, or PDCD10 (CCM3), the genetic cause of sporadic CCMs, represen
ting 80% of cases, remains incompletely understood. METHODS: We developed two mouse models harboring mutations identified in human meningiomas with the use of the prostaglandin D2 synthase (PGDS) promoter. We performed targeted DNA sequencing of surgically resected CCMs from patients and confirmed our findings by droplet digital polymerase-chain-reaction analysis. RESULTS: We found that in mice expressing one of two common genetic drivers of meningioma - Pik3ca H1047R or AKT1 E17K - in PGDS-positive cells, a spectrum of typical CCMs develops (in 22% and 11% of the mice, respectively) instead of meningiomas, which prompted us to analyze tissue samples from sporadic CCMs from 88 patients. We detected somatic activating PIK3CA and AKT1 mutations in 39% and 1%, respectively, of lesion tissue from the patients. Only 10% of lesions harbored mutations in the CCM genes. We analyzed lesions induced by the activating mutations Pik3ca H1074R and AKT1 E17K in mice and identified the PGDS-expressing pericyte as the probable cell of origin. CONCLUSIONS: In tissue samples from sporadic CCMs, mutations in PIK3CA were represented to a greater extent than mutations in any other gene. The contribution of somatic mutations in the genes that cause familial CCMs was comparatively small. (Funded by the Fondation ARC pour la Recherche contre le Cancer and others.).
Orloff MS, etal., Am J Hum Genet. 2013 Jan 10;92(1):76-80. doi: 10.1016/j.ajhg.2012.10.021. Epub 2012 Dec 13.
Cowden syndrome (CS) is a difficult-to-recognize multiple hamartoma syndrome with high risks of breast, thyroid, and other cancers. Germline mutations in PTEN on 10q23 were found to cause 85% of CS when accrued from tertiary academic centers, but prospective accrual from the community over the last
12 years has revealed a 25% PTEN mutation frequency. PTEN is the phosphatase that has been implicated in a heritable cancer syndrome and subsequently in multiple sporadic cancers and developmental processes. PTEN antagonizes the AKT1/PI3K signaling pathway and has roles in cell cycle, migration, cell polarity, and apoptosis. We report that 8 of 91 (8.8%) unrelated CS individuals without germline PTEN mutations carried 10 germline PIK3CA mutations (7 missense, 1 nonsense, and 2 indels) and 2 (2.2%) AKT1 mutations. These mutations result in significantly increased P-Thr308-AKT and increased cellular PIP3. Our observations suggest that PIK3CA and AKT1 are CS susceptibility genes.
Zhou H, etal., Mol Med Rep. 2019 Mar;19(3):2125-2136. doi: 10.3892/mmr.2019.9886. Epub 2019 Jan 22.
AT‑rich interaction domain 1A (ARID1A) and phosphatidylinositol‑4,5‑bisphosphate 3‑kinase catalytic subunit α (PIK3CA) serve important roles in the formation and development of numerous malignancies including gastric cancer. Accumulating evidence has demon
strated that Epstein‑Barr virus (EBV) is a pathogenic virus associated with gastric cancer. The present study aimed to investigate the association between EBV infection, and the expression levels of ARID1A and PIK3CA in gastric cancer. EBER in situ hybridization was performed to detect EBV infection. Immunohistochemistry was used to assess the expression levels of ARID1A and PIK3CA in gastric cancer and adjacent normal tissues. A total of 58 gastric cancer and 10 adjacent normal tissues were tested for genetic mutations via single nucleotide polymorphism genotyping assays. Fluorescent polymerase chain reaction was used to detect EBV infection; 9.3% (28/300) of gastric cancer samples were positive for EBV, whereas, all adjacent normal tissues were negative. ARID1A and PIK3CA were negatively correlated in gastric cancer (r=‑0.167). The expression levels of ARID1A and PIK3CA in gastric cancer were significantly associated with the depth of invasion of gastric cancer. A total of 62.1% (36/58) of tumor samples exhibited mutations in ARID1A, whereas, 13.8% (8/58) presented mutations in PIK3CA. Notably, EBV‑associated gastric cancer (EBVaGC) samples with PIK3CA mutations additionally exhibited ARID1A mutations. Although in the present study it was identified that ARID1A and PIK3CA were negatively correlated in EBVaGC, further studies are required to investigate the association among ARID1A, PIK3CA and EBV in gastric cancer.
Kim ST, etal., Oncotarget. 2015 Nov 24;6(37):40026-35. doi: 10.18632/oncotarget.5432.
PIK3CA mutation is considered a good candidate for targeted therapies in cancers, especially biliary tract cancer (BTC). We evaluated the utility of cell free DNA (cfDNA) from serum by using droplet digital PCR (ddPCR) as an alternative source for PIK3CA
'font-weight:700;'>PIK3CA mutation analysis. To identify matching archival tumour specimens from serum samples of advanced BTC patients, mutation detection using ddPCR with Bio-Rad's PrimePCR mutation and wild type assays were performed for PIK3CA p.E542K, p.E545K, and p.H1047R. Thirty-eight patients with metastatic BTC were enrolled. Only one (BTC 29T) sample (n = 38) was positive for PIK3CA p.E542K and another (BTC 27T) for p.H1047R mutation; none was positive for PIK3CA p.E545K. Matched serum sample (BTC 29P) was positive for PIK3CA p.E542K with 28 mutant copies detected, corresponding to 48 copies/ml of serum and an allelic prevalence of 0.3%. Another matched serum sample (BTC 27P) was positive for PIK3CA p.H1047R with 10 mutant copies detected, i.e. 18 copies/ml and an allelic frequency of 0.2%. High correlation was noted in the PIK3CA mutation status between tumour gDNA and serum cfDNA. Low-level PIK3CA mutations were detectable in the serum indicating the utility of cfDNA as a DNA source to detect cancer-derived mutations in metastatic biliary cancers.
Rios JJ, etal., Hum Mol Genet. 2013 Feb 1;22(3):444-51. doi: 10.1093/hmg/dds440. Epub 2012 Oct 24.
Macrodactyly is a discrete congenital anomaly consisting of enlargement of all tissues localized to the terminal portions of a limb, typically within a 'nerve territory'. The classic terminology for this condition is 'lipofibromatous hamartoma of nerve' or Type I macrodactyly. The peripheral nerve,
itself, is enlarged both in circumference and in length. It is not related to neurofibromatosis (NF1), nor is it associated with vascular malformations, such as in the recently reported CLOVES syndrome. The specific nerve pathophysiology in this form of macrodactyly has not been well described and a genetic etiology for this specific form of enlargement is unknown. To identify the genetic cause of macrodactyly, we used whole-exome sequencing to identify somatic mutations present in the affected nerve of a single patient. We confirmed a novel mutation in PIK3CA (R115P) present in the patient's affected nerve tissue but not in blood DNA. Sequencing PIK3CA exons identified gain-of-function mutations (E542K, H1047L or H1047R) in the affected tissue of five additional unrelated patients; mutations were absent in blood DNA available from three patients. Immunocytochemistry confirmed AKT activation in cultured cells from the nerve of a macrodactyly patient. Additionally, we found that the most abnormal structure within the involved nerve in a macrodactylous digit is the perineurium, with additional secondary effects on the axon number and size. Thus, isolated congenital macrodactyly is caused by somatic activation of the PI3K/AKT cell-signaling pathway and is genetically and biochemically related to other overgrowth syndromes.
Li HG, etal., Int J Clin Exp Pathol. 2015 Nov 1;8(11):15255-9. eCollection 2015.
PURPOSE: Our study was carried out to explore the relationship of PIK3CA rs17849071 and rs17849079 polymorphisms with the susceptibility to hepatocellular carcinoma (HCC) in Chinese Han population. METHODS: 150 HCC patients and 152 healthy individuals were recru
ited in the case and control groups respectively. The genotypes of PIK3CA rs17849071 and rs17849079 polymorphisms were detected with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The linkage disequilibrium and haplotypes were analyzed with Haploview software. Differences in frequencies of genotypes, alleles, and haplotypes between the case and control groups were checked with chi(2) test. The controls were matched with the cases in age and gender. The relative risk of HCC was represented by odds ratio (OR) and 95% confidence interval (95% CI). RESULTS: Significant difference in frequencies of GG genotype and G allele in PIK3CA rs17849071 polymorphism existed between the two groups (P=0.040; P=0.028), indicating that rs17849071 was closely related to the increased risk of HCC (OR=2.919, 95% CI=1.007-8.460; OR=1.642, 95% CI=1.051-2.564). Furthermore, TT genotype also significantly increased the susceptibility to HCC (OR=3.438, 95% CI=1.050-11.250) and so was T allele (OR=1.521, 95% CI=1.052-2.199). The haplotype analysisshowed that G-T haplotypes were higher in cases than that of controls (P=0.030), which suggested that G-T might be a susceptible haplotype to HCC. CONCLUSIONS: The PIK3CA rs17849071 and rs17849079 polymorphisms may increase the risk of HCC either independently or synergistically.
Li B, etal., Int J Clin Exp Pathol. 2015 Jul 1;8(7):8563-7. eCollection 2015.
BACKGROUND: Undifferentiated pleomorphic sarcoma (UPS), previously known as malignant fibrous histiocytoma, comprises a series of high-grade soft tissue sarcomas, which fail to exhibit any specific line of differentiation by using currently available ancillary techniques. Studies on gene mutation sc
reening occurring in UPS are rarely conducted. In this study, we described a case of UPS and analyzed its mutation changes. We detected 19 hotspot oncogenes in the case. To the best of our knowledge, this study is the first to use a high-throughput OncoCarta panel 1.0 and MassARRAY system to detect 238 known mutations in 19 hotspot oncogenes in UPS. In this study, our result revealed two missense mutations, namely, KRAS mutation (35G > A, G12D) and PIK3CA mutation (1636C > A, Q546K) in the case.
Shi ZC, etal., Tumour Biol. 2015 Nov;36(11):8579-84. doi: 10.1007/s13277-015-3614-9. Epub 2015 Jun 3.
Osteosarcoma has become one of the most common primary malignant bone tumors in childhood and adult. Numerous studies have demonstrated that aberrant microRNA (miRNA) expression is involved in human disease including cancer. To date, the potential miRNAs regulating osteosarcoma growth and progressio
n are not fully identified yet. Herein, we showed that miR-375 was frequently downregulated in osteosarcoma tissue and cell lines compared to normal human colon tissues. Overexpression of miR-375 resulted in decreased expression of PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha) at both mRNA and protein levels. We found that miR-375 overexpression markedly suppressed cell proliferation in vitro. And inhibition of miR-375 promotes osteosarcoma growth. Mechanistic studies showed that PIK3CA was a potential target of miR-375 and it mediated reduction of PIK3CA resulted in suppression of PI3K/Akt pathway. Taken together, our results demonstrate that miR-375 functions as a growth-suppressive miRNA and plays an important role in inhibiting the tumorigenesis through targeting PIK3CA in osteosarcoma.
PIK3CA is the only frequently-mutated, directly druggable oncogene in head and neck squamous cell carcinoma (HNSCC). However, it is unclear if a molecularly-driven intervention trial can be launched successfully, particularly within a single-institution setting
secondary to the infrastructure necessary for mutation detection, mutation prevalence, and patient willingness to participate. This study aimed to evaluate 1) local frequency of PIK3CA activating mutations in HNSCC, 2) timeliness of our mutation-profiling clinical pathway, and 3) patients' willingness to enroll in a novel neoadjuvant drug trial. Tissue biopsies of 25 consecutive cases of HNSCC were tested for activating PIK3CA mutations at three mutational hotspots by real-time polymerase chain reaction. Mutations prevalence and number of working days accrued in determining PIK3CA mutational status were calculated. In addition, 30 HNSCC patients were surveyed prospectively regarding their willingness to participate in a hypothetical drug trial. Survey data were summarized descriptively. 4 of 25 (16 %) tumors harbored a PIK3CA activating mutation, including one at codon E542K, two at codon E545K/D, and one at codon H1047R. On average, this result was obtained in approximately 15 working days (range, 9-24 working days). The majority of patients surveyed (70 %) indicated their willingness to participate in a targeted PIK3CA trial. This study provides evidence that within a single institution, PIK3CA activating mutations can be detected with expected frequency, with sufficient timeliness and sufficient patient interest to mount a targeted intervention trial that may lead to improved tumor response in selected HNSCC patients.
Parsafar S, etal., Cancer Biomark. 2015;15(4):397-403. doi: 10.3233/CBM-150487.
BACKGROUND: Activated PI3K generate PIP3 to trigger different signaling pathways which regulate a number of cellular functions including cell survival, apoptosis, proliferation and motility. Mutations in many cancers were discovered in the gene encoding the PI3K catalytic subunit, PIK3CA
-weight:700;'>PIK3CA. OBJECTIVE: To date, there has been no report on the association between polymorphism of PIK3CA gene microsatellites and risk of colorectal cancer. In this study, we investigate the relation between the GT dinucleotide repeat in intron 1 of the PIK3CA gene and colorectal cancer risk. METHODS: A case-control study of 103 colorectal cancer patients and 150 controls was conducted in Iranian people. RESULTS: The results of our study demonstrate that PIK3CA gene allele distribution in Iranian population varies between 13 and 20 repeats. Here we demonstrate that individuals who carry alleles shorter than 17 GT repeat are at higher risk of developing colorectal cancer (OR = 4.0, p= 0), by contrast, those individuals with two alleles longer than 16 GT repeats are at a significantly lower risk of developing colorectal cancer (OR = 0.12, p= 0). CONCLUSION: This result suggests polymorphic GT repeat of PIK3CA gene may be a potential predictive marker of colorectal cancer risk in Iranian population.
Tanaka Y, etal., Oncogene. 2006 May 11;25(20):2950-2. doi: 10.1038/sj.onc.1209311.
A recent study revealed that the p110alpha (PIK3CA), catalytic subunit of phosphatidylinositol 3-kinase (PI3K), is somatically mutated in many types of cancer. For example, PIK3CA is mutated in an estimated 35.6% of hepatoce
llular carcinoma (HCC) cases. To measure the frequency of PIK3CA hotspot mutations in Japanese HCC patients, exons 9 and 20 of the PIK3CA gene were sequenced in 47 clinical HCC samples. Contrary to expectations, no hotspot mutations were found any of the HCC samples. In addition, we found abnormally migrating waves near the end of exon 9 in the PCR chromatograms from 13 of the 47 samples. PCR amplification and subsequent cloning and sequencing revealed that these chromatograms contained two distinct sequences, the wild-type p110alpha sequence and a different sequence found on human chromosome 22q11.2, the Cat Eye Syndrome region, which contains a putative pseudogene of PIK3CA. These abnormally migrating waves were also found in noncancerous liver tissue, indicating that this was not a result of HCC-associated mutations. Therefore, it is likely that the percentage of hotspot mutations in the PIK3CA gene of Japanese HCC patients is lower than was previously reported.
BACKGROUND INFORMATION: Dysregulated micro-RNAs have been reported in many human cancers, including renal cell carcinoma. Recent studies indicated that miR-490 is involved in tumour development and progression. However, the expression profile and function in renal cell carcinoma remains unknown. RE
SULTS: Herein, we showed that miR-490-5p was down-regulated in renal cell carcinoma tissues and cells compared with the adjacent normal tissues and normal cells. We also provided evidence that miR-490-5p acts as a tumour suppressor in renal carcinoma in a variety of in vitro and in vivo assays. Mechanistically, miR-490-5p was verified to directly bind to 3' UTR of the PIK3CA mRNA and reduce the expression of PIK3CA at both mRNA and protein levels, which further inhibits phosphatidylinositol 3-kinase/Akt signalling pathway. We further showed that knockdown of PIK3CA can block the growth inhibitory effect of miR-490-5p, and over-expression of PIK3CA can reverse the inhibitory effect of miR-490-5p on renal cancer cell tumourigenicity. CONCLUSIONS: Taken together, our results indicated for the first time that miR-490-5p functions as a tumour suppressor in renal carcinoma by targeting PIK3CA. SIGNIFICANCE: Our findings suggest that miR-490-5p may be a potential gene therapy target for the treatment of renal cell carcinoma.
BACKGROUND: Triple Negative Breast Cancer (TNBC) accounts for 12-24% of all breast carcinomas, and shows worse prognosis compared to other breast cancer subtypes. Molecular studies demonstrated that TNBCs are a heterogeneous group of tumors with different clinical and pathologic features, prognosis
, genetic-molecular alterations and treatment responsivity. The PI3K/AKT is a major pathway involved in the regulation of cell survival and proliferation, and is the most frequently altered pathway in breast cancer, apparently with different biologic impact on specific cancer subtypes. The most common genetic abnormality is represented by PIK3CA gene activating mutations, with an overall frequency of 20-40%. The aims of our study were to investigate PIK3CA gene mutations on a large series of TNBC, to perform a wider analysis on genetic alterations involving PI3K/AKT and BRAF/RAS/MAPK pathways and to correlate the results with clinical-pathologic data. MATERIALS AND METHODS: PIK3CA mutation analysis was performed by using cobas(R) PIK3CA Mutation Test. EGFR, AKT1, BRAF, and KRAS genes were analyzed by sequencing. Immunohistochemistry was carried out to identify PTEN loss and to investigate for PI3K/AKT pathways components. RESULTS: PIK3CA mutations were detected in 23.7% of TNBC, whereas no mutations were identified in EGFR, AKT1, BRAF, and KRAS genes. Moreover, we observed PTEN loss in 11.3% of tumors. Deregulation of PI3K/AKT pathways was revealed by consistent activation of pAKT and p-p44/42 MAPK in all PIK3CA mutated TNBC. CONCLUSIONS: Our data shows that PIK3CA mutations and PI3K/AKT pathway activation are common events in TNBC. A deeper investigation on specific TNBC genomic abnormalities might be helpful in order to select patients who would benefit from current targeted therapy strategies.
The aim of this study was to evaluate the clinicopathological and prognostic relevance of PIK3CA mutations in Chinese patients with surgically resected cervical cancer. PIK3CA mutations were screened in 771 cervical cancer s
pecimens using reverse transcription polymerase chain reaction and Sanger sequencing. In total, 13.6% (105 of 771) of patients harbored non-synonymous PIK3CA mutations. Patients harboring PIK3CA mutations were older than patients with wild-type PIK3CA (mean age: 50.7 years vs. 47.0 years, P < 0.01). PIK3CA mutations were more commonly observed in postmenopausal patients than in premenopausal patients (19.6% vs. 10.2%, P < 0.01). PIK3CA mutations were more common in squamous cell carcinomas than in non-squamous cell tumors (15.3% vs 7.3%, of P < 0.01). The 3-year relapse-free survival was 90.2% for PIK3CA mutant patients and 80.9% for PIK3CA wild-type patients (P = 0.03). PIK3CA mutation was confirmed as an independent predictor for better treatment outcome in the multivariate analyses (HR = 0.54, 95% CI: 0.29-0.99, P = 0.048). PIK3CA mutations were significantly associated with less distant metastases (mutant-type: 8/105, wild-type: 98/666, p = 0.048). Thus, patients with mutant PIK3CA had distinct characteristics in age, menopausal status, and histological subtype and have better treatment outcome and less distant metastasis after surgery-based multimodal therapy.
Liedtke C, etal., Breast Cancer Res. 2008;10(2):R27. doi: 10.1186/bcr1984. Epub 2008 Mar 27.
INTRODUCTION: In vitro evidence suggests that PIK3CA (phosphatidylinositol 3-kinase, catalytic, alpha polypeptide) activation may be associated with altered chemotherapy sensitivity in cancer. METHODS: Tumor DNA from 140 patients with stage II-III breast cancer
undergoing neoadjuvant chemotherapy was sequenced for PIK3CA mutations on exons 1, 9, and 20. Mutation status was correlated with clinical/pathological parameters and chemotherapy response as (a) pathological complete response (pCR) versus residual cancer or (b) quantitative residual cancer burden (RCB) scores, including stratification for estrogen receptor (ER) expression status, type of chemotherapy, and by exons. RESULTS: Twenty-three patients (16.4%) harbored a PIK3CA mutation, with 12, 11, and 0 mutations located in exons 9, 20, and 1, respectively. PIK3CA exon 9 mutations were more frequent among node-negative (52% versus 25%; P = 0.012) than node-positive tumors, particularly among ER-positive tumors. pCR rates and RCB scores were similar among patients with the wild-type and mutant PIK3CA genes, even after stratification by ER status, chemotherapy regimen (anthracycline versus anthracycline plus paclitaxel), or exon. CONCLUSION: PIK3CA mutations are not associated with altered sensitivity to preoperative anthracycline-based or taxane-based chemotherapies in ER-positive and ER-negative breast tumors. In this study, PIK3CA mutation was associated with a decreased rate of node-positive disease, particularly among ER-positive tumors.
Guo XN, etal., Cancer Res. 2007 Jun 15;67(12):5851-8.
Mutations in the PIK3CA gene are common in human cancers, including colon cancer. We compared two pairs of colon cancer cells (HCT116 and DLD1) bearing only the wild-type (WT) or mutant (MUT) PIK3CA allele for their survival
capacity under stress conditions in vitro as well as their metastatic properties in an in vivo orthotopic model. When subjected to growth factor deprivation stress (GFDS), the MUT PIK3CA cells displayed resistance to GFDS-induced apoptosis relative to the WT cells. Phosphatidylinositol 3-kinase (PI3K) and its downstream effector AKT were constitutively activated during stress conditions in the MUT PIK3CA cells but not in the WT cells. The MUT cells showed hypersensitivity to PI3K inhibition. Moreover, the proapoptotic protein Bax was expressed at a very high level in the WT PIK3CA cells, whereas it was almost undetectable in the MUT cells. Inhibition of Bax expression by small interfering RNA protected the WT PIK3CA cells from GFDS-induced apoptosis, suggesting an important role of Bax in GFDS-induced apoptosis. These results indicated that the MUT PI3K confers resistance to GFDS-induced apoptosis and that the MUT cells are more dependent on the PI3K pathway for survival. In vivo studies showed that the MUT PIK3CA-bearing cells were more metastatic than the WT cells in an orthotopic model of colon cancer. Taken together, these results suggest that MUT PI3K imparts a more aggressive phenotype in colon cancer cells and could be a potential therapeutic target for treatment of colon cancer patients bearing PIK3CA mutations.
Wang YL, etal., Genet Mol Res. 2015 Nov 23;14(4):14840-6. doi: 10.4238/2015.November.18.49.
Phosphatidylinositol-3-OH kinase and RAS-activated signaling pathways play an important role in tumor formation. Abnormalities in relevant genes play essential roles in the occurrence and development of many human cancers. Studies of breast cancer have mainly focused on the women in western countri
es, but few studies have examined the frequency of mutations in PIK3CA, BRAF, and KRAS in Chinese breast cancer patients. In this study, we conducted sequence analysis of PIK3CA, BRAF, and KRAS and determined relationships with the occurrence of breast cancer in women from Qinghai. DNA was extracted from 25 cases of human breast cancer tissue samples. PIK3CA, BRAF, and KRAS mutation analysis was performed by polymerase chain reaction and DNA sequencing. No mutations were found in PIK3CA, BRAF, and KRAS of adjacent tissues. However, PIK3CA mutations were observed in 32% (8) of the 25 breast cancer tissues examined, in which exon 9 accounted for 4% (1), exon 20 accounted for 28% (7), and no mutations were found in exon 1 of PIK3CA. Sequencing of exon 2 of KRAS suggested that 20% (5) of the 25 samples harbored a mutation and 16% (4) of BRAF harbored a mutation. Any mutation in these 3 oncogenes may induce the occurrence and development of breast cancer.
Wen F, etal., Int J Clin Exp Pathol. 2014 Oct 15;7(11):8295-303. eCollection 2014.
The phosphoinositide 3-kinases (PI3Ks) are a critical family of signaling enzymes that participate in many cellular processes that promote the transformation of a normal cell into a cancer cell. These processes include cancer cell proliferation, migration, and invasion. However, the correlation betw
een PI3Ks and multidrug resistance (MDR) remains unclear. The prognostic value of PI3Ks has not been previously evaluated. Thus, this study aims to evaluate the association between PIK3CA and PIK3CB expression and the MDR gene in colorectal cancer (CRC) patients. Immunohistochemistry was employed to detect the expressions of PIK3CA, PIK3CB, MDR-1, LRP, GST-p, and Topo II in 316 CRC specimens. Patients were followed-up annually by telephone or at an outpatient clinic. Results revealed that PIK3CA and PIK3CB expression was correlated with the degree of tumor differentiation and lymph node metastasis (P < 0.05). The overexpression of MDR-1, LRP, Topo II, and GST-p was found to be 72.78%, 70.89%, 77.53%, and 76.58% of CRC, respectively. Correlation analysis showed that PIK3CA and PIK3CB expression exhibits a positive correlation with MDR-1, LRP, and GST-p with correlation coefficients of 0.288, 0.128, and 0.197, respectively (P < 0.05). Kaplan-Meier analysis revealed that the five-year survival rate of patients without lymph node metastasis, positive expression of PIK3CA and PIK3CB, and negative expression of GST-p and MDR-1 was higher than those with these characteristics. Multivariate analysis revealed that GST-p, MDR-1 expression, and lymph node metastasis could serve as independent predictive factors of overall survival. The expression of both PIK3CA and PIK3CB is increased and related to the development and progress of colorectal carcinoma and MDR. The combined detection of PIK3CA andPIK3CB is important for patients with colorectal carcinoma in prognosis and optimal therapy.
Ekinci S, etal., Genet Test Mol Biomarkers. 2015 Jul;19(7):353-8. doi: 10.1089/gtmb.2015.0060. Epub 2015 Jun 8.
AIMS: The aim of the present study was to obtain the first data for the phosphatidylinositol-4,5-bisphosphate 3-kinase (PIK3CA) mutation frequency among nonsmall-cell lung cancer (NSCLC) patients in Turkey. All exons of the PIK3CA
gene were investigated by sequence analysis in 40 NSCLC tumor tissue samples. RESULTS: The 1634A>C mutation, which has previously been identified in many cancers including NSCLC, was identified in three tumor tissue samples in the present study. Interestingly, a second mutation (1658_1659delGTinsC) was also identified in these patients. The concurrence of these two mutations has been reported as the Cowden syndrome, which is known to be a cancer predisposition syndrome. This finding is important since it may be an indicator of the underlying cancer predisposition syndrome in NSCLC patients. Moreover, four novel mutations were identified in the present study. However, in vitro studies are required to evaluate the effects of these mutations on kinase activation. CONCLUSIONS: The high frequency of PIK3CA mutations exerts important clinical implications for targeted therapy. This finding indicates that therapeutic agents targeting the phosphatidylinositol 3-kinase (PI3K) would be beneficial in the NSCLC subpopulation.
OBJECTIVE: PI3K/Akt signalling pathway is frequently activated in several types of cancer. However, activator molecules have not been analysed systematically in HNSCC. The aim of this study was to investigate upstream activators and inhibitors of this pathway. DESIGN: Prospective study. SETTING: Un
iversity hospital. PARTICIPANTS: 108 patients with HNC who were operated at the Istanbul University, Cerrahpasa Medical Faculty, Department of Otorhinolaryngology. METHODS: Mutations in the coding exons and the flanking intronic sequences of the PIK3CA, PIK3R1 and AKT1 genes were analysed by direct sequencing. Expression levels in the tumours and non-cancerous tissue samples were analysed by quantitative RT-PCR, and Western blotting was performed to determine the phosphorylation levels of the Akt1 protein. RESULTS: Two synonymous alterations in exon 20 of the PIK3CA gene, a 6-bp duplication in the coding region of the PIK3R1 and two different alterations in the non-coding regions of the AKT1 and PIK3R1 genes were observed. Significant downregulation of LKB1 and PTEN mRNA expression levels were detected in tumour tissues compared to non-cancerous tissues. However, we did not observe any difference between the PIK3CA and AKT1 mRNA expression levels in the tumours and non-cancerous tissue samples. Akt1 phosphorylation was increased in 53.57% of the patients. CONCLUSIONS: Our results indicate that the PI3K pathway has an important function in HNSCC progression with the contribution of more than one gene of this pathway. Our data suggest that in a high number of HNSCC tumours, PI3K/Akt signalling is activated by different molecules or by the combination of these molecules.
Wu Y, etal., Int J Clin Exp Pathol. 2015 Nov 1;8(11):14479-85. eCollection 2015.
PURPOSE: Esophageal squamous cell carcinoma (ESCC) is one of the most fatal cancers worldwide. However, the etiology is complex and unclear. 3q26 harboring abundant oncogenes have been identified as the loci of ESCC susceptibility. In the present study, we examined whether CNVs on 3q26 would be asso
ciated with the risk, TNM stage and prognosis of ESCC. METHODS: Variation_91720 in phosphatidylinositol 3-kinase catalytic subunit (PIK3CA) and Variation_91733 in sex-determining region Y-box 2 overlapping transcript (SOX2OT) were selected for investigation. The study included 204 ESCC patients and 208 healthy controls. The copy number of the selected sites and mRNA was detected by real-time fluorescence quantitative polymerase chain reaction and calculated using the CopyCaller v2.0 software program. RESULTS: The copy number distribution of Variation_91720 was significantly different in ESCC cases and matched controls (p<0.001). Copy number loss of Variation_91720 may increase the risk of ESCC (OR=6.217, 95% CI=3.117-12.400; adjusted OR =6.251, 95% CI=3.130-12.428). PIK3CA mRNA expression was higher in tumor tissue (P=0.0003) and increased with the copy number gain of Variation_91720. CONCLUSION: Our findings suggest that copy number loss of Variation_91720 in PIK3CA predicts risk of ESCC, which might serve as a biomarker that for early diagnosis of ESCC.
Takeshita T, etal., Cancer Sci. 2015 Nov;106(11):1582-9. doi: 10.1111/cas.12813. Epub 2015 Oct 30.
PIK3CA is an oncogene that encodes the p110alpha component of phosphatidylinositol 3-kinase (PI3K); it is the second most frequently mutated gene following the TP53 gene. In the clinical setting, PIK3CA mutations may have f
avorable prognostic value for hormone receptor-positive breast cancer patients and, during the past few years, PIK3CA mutations of cell-free DNA (cfDNA) have attracted attention as a potential noninvasive biomarker of cancer. However, there are few reports on the clinical implications of PIK3CA mutations for TNBC patients. We investigated the PIK3CA major mutation status of cfDNA as a noninvasive biomarker of cancer using droplet digital polymerase chain reaction (ddPCR), which has high level sensitivity and specificity for cancer mutation, in early-stage 49 triple negative breast cancer (TNBC) patients. A total of 12 (24.4%) of 49 patients had PIK3CA mutations of cfDNA. In a median follow up of 54.4 months, the presence of PIK3CA mutations of cfDNA had significant impacts on relapse-free survival (RFS; P = 0.0072) and breast cancer-specific survival (BCSS; P = 0.016), according to the log-lank test. In a Cox proportional hazards model, the presence of PIK3CA mutations of cfDNA had significant prognostic value in the univariate and multivariate analysis. Additionally, the presence of PIK3CA mutations of cfDNA was significantly correlated with positive androgen receptor phosphorylated form depending on PI3K signaling pathway (pAR) which is independent favorable prognostic factors of TNBC. We demonstrated that the presence of PIK3CA major mutations of cfDNA could be a discriminatory predictor of RFS and BCSS in early-stage TNBC patients and it was associated with PI3K pathway-dependent AR phosphorylation.
Sequence mutations and gene amplifications lead to activation of the PIK3CA-AKT2 signaling pathway and have been reported in several types of neoplasms including ovarian cancer. Analysis of such genetic alterations, however, is usually complicated by contaminati
on of normal cell DNA, artifacts associated with formalin-fixed tissues and the sensitivity of the techniques employed. In this study, we analyzed the sequence mutations in PIK3CA and AKT2 genes using purified tumor cells that were isolated from high-grade ovarian serous carcinomas and serous borderline tumors (SBTs) and assessed gene amplification using a dual-color FISH on tissue microarrays. Somatic sequence mutations in the kinase domain of AKT2 were not detected in any of the 65 ovarian tumors analyzed. Mutations of PIK3CA were rare, occurring only in one (2.3%) of 44 high-grade serous carcinomas and in only one (4.8%) of 21 SBTs. Dual-color FISH demonstrated that PIK3CA and AKT2 were not amplified in SBTs but amplified in 13.3% and 18.2% high-grade carcinomas, respectively. High-level amplification (>3 fold) was more frequently observed in AKT2 than in PIK3CA. Unlike mutations in ERBB2, KRAS and BRAF which are mutually exclusive in SBTs, coamplification of PIK3CA and AKT2 was present in five high-grade carcinomas including the OVCAR3 cells. Amplification in either of the genes occurred in 27% high-grade serous carcinomas. In conclusion, the methods we employed provide unambiguous evidence that somatic sequence mutations of PIK3CA and ATK2 are rare in ovarian serous tumors but amplification of both genes may play an important role in the development of high-grade ovarian serous carcinoma.
Liang L, etal., Zhonghua Wai Ke Za Zhi. 2012 Nov;50(11):1007-10.
OBJECTIVE: To investigate PIK3CA, PTEN status in the primary lesion of colorectal cancer (CRC): relationship with occurrences of liver metastasis and its prognosis. METHODS: Patients with CRC who had the primary tumor resected between 2003 a
nd 2008 were selected and enrolled into three groups according to the occurrence of liver metastasis. The mutations of PIK3CA exon 9 and 20, PTEN exon 5, 7, 8 in primary cancer cells in formalin-fixed, paraffin-embedded specimens were detected by Pyrosequencing, then a statistical analysis was deduced to find out the relationship between PIK3CA, PTEN status and occurrences of liver metastasis as well as the prognosis. RESULTS: Of all the 300 CRC cases, the mutation rates of PIK3CA and PTEN was 18.2% (51/300) and 16.3% (49/300). The multivariate Logistic analysis revealed that exon 5 mutation of PTEN was one of the independent risk factors of occurrence of metachronous liver metastasis in CRC patients (HR = 1.634, 95%CI: 1.796 - 3.355, P = 0.041). Patients with PTEN mutation had a poorer overall survival in group with synchronous liver metastasis (median survival time 62.0 months vs 71.0 months, χ(2) = 12.942, P = 0.048) while CRC patients who had the liver metastasis resected in group of synchronous and metachronous liver metastasis had a poorer disease free survival rates with PIK3CA mutation (median survival time 16.0 months vs 25.0 months, χ(2) = 9.679, P = 0.037). CONCLUSIONS: The exon 5 mutation of PTEN of CRC is potentially correlated with the occurrence of synchronous liver metastasis. CRC patients who had the liver metatasis resected but with PIK3CA mutation could have a poorer prognosis.
Mutational testing has moved to the forefront as an integral component in the management of patients with non-small cell lung cancer (NSCLC). Currently 3 targeted therapies (erlotinib, afatinib, and crizotinib) are approved by the FDA to treat patients with specific genetic abnormalities in NSCLC.
As mutational screening expands to include a greater number of genes, the results will become more difficult to interpret, particularly if mutations are found in multiple genes or genes that are not actionable at the time of testing. This case report summarizes the diagnosis and treatment of a patient with NSCLC that harbored multiple potentially targetable driver mutations. It also discusses the current NCCN Clinical Practice Guidelines in Oncology for mutational testing in NSCLC and the inherent difficulties with interpreting mutational results when multiple mutations are found in a single gene or across multiple genes.
Young CD, etal., Mol Cell Proteomics. 2015 Jul;14(7):1959-76. doi: 10.1074/mcp.M115.049783. Epub 2015 May 7.
Mutations in PIK3CA, the gene encoding the p110alpha catalytic subunit of phosphoinositide 3-kinase (PI3K) have been shown to transform human mammary epithelial cells (MECs). These mutations are present in all breast cancer subtypes, including basal-like breast
cancer (BLBC). Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), we identified 72 protein expression changes in human basal-like MECs with knock-in E545K or H1047R PIK3CA mutations versus isogenic MECs with wild-type PIK3CA. Several of these were secreted proteins, cell surface receptors or ECM interacting molecules and were required for growth of PIK3CA mutant cells as well as adjacent cells with wild-type PIK3CA. The proteins identified by MS were enriched among human BLBC cell lines and pointed to a PI3K-dependent amphiregulin/EGFR/ERK signaling axis that is activated in BLBC. Proteins induced by PIK3CA mutations correlated with EGFR signaling and reduced relapse-free survival in BLBC. Treatment with EGFR inhibitors reduced growth of PIK3CA mutant BLBC cell lines and murine mammary tumors driven by a PIK3CA mutant transgene, all together suggesting that PIK3CA mutations promote tumor growth in part by inducing protein changes that activate EGFR.
Hechtman JF, etal., Mol Cancer Res. 2015 Jun;13(6):1003-8. doi: 10.1158/1541-7786.MCR-15-0062-T. Epub 2015 Feb 24.
The PI3K/AKT/mTOR pathway is activated through multiple mechanisms in colorectal carcinoma. Here, the clinicopathologic and molecular features of AKT1 E17K-mutated colorectal carcinoma in comparison with PIK3CA-mutated colorectal carcinoma are described in deta
il. Interestingly, in comparison with PIK3CA mutants, AKT1 E17K was significantly associated with mucinous morphology and concurrent BRAF V600E mutation. Among PIK3CA mutants, exon 21 mutations were significantly associated with BRAF V600E mutation, MSI-H status, and poor differentiation, while exon 10 mutations were associated with KRAS/NRAS mutations. Three of four AKT1 mutants with data from both primary and metastatic lesions had concordant AKT1 mutation status in both. Both AKT1- and PIK3CA-mutant colorectal carcinoma demonstrated frequent loss of PTEN expression (38% and 34%, respectively) and similar rates of p-PRAS 40 expression (63% and 50%, respectively). Both patients with AKT1 E17K alone had primary resistance to cetuximab, whereas 7 of 8 patients with PIK3CA mutation alone experienced tumor shrinkage or stability with anti-EGFR therapy. These results demonstrate that AKT1 E17K mutation in advanced colorectal carcinoma is associated with mucinous morphology, PIK3CA wild-type status, and concurrent RAS/RAF mutations with similar pattern to PIK3CA exon 21 mutants. Thus, AKT1 E17K mutations contribute to primary resistance to cetuximab and serve as an actionable alteration. IMPLICATIONS: This first systematic study of AKT1 and PIK3CA hotspot mutations and their association with cetuximab resistance and BRAF V600E mutation has important ramifications for the development of personalized medicine, particularly in identifying patient candidates for PI3K or AKT inhibitors.
Bozhanov SS, etal., J Cancer Res Clin Oncol. 2010 Nov;136(11):1657-69. doi: 10.1007/s00432-010-0824-9. Epub 2010 Feb 23.
PURPOSE: Though p53, BRCA1, ATM, PIK3CA, and HER2 genes are shown to be involved in various aspects of breast carcinogenesis, their functional relationship and clinical value are still disputable. We investigated the genetic status or expression profile of thes
e genes to further elucidate their clinical significance. METHODS: PCR-SSCP-Sequencing of p53, BRCA1, ATM, and PIK3CA was performed in 145 Bulgarian patients with sporadic breast cancer. Expression profiles of HER2 were determined by ICH and CISH. Relationship between mutations and clinicopathological characteristics was evaluated by Chi-squared and Fisher's exact tests. Multivariate Cox proportional hazard test and Kaplan-Meier analysis were used to evaluate differences in overall survival between groups. RESULTS: The frequency of p53 (22.07%), BRCA1 (0.69%), ATM (7.59%), and PIK3CA (31.25%) alterations and HER2 (21.21%) overexpression was estimated. Mutated p53 was associated with tumor size (P = 0.033) and grade of malignancy (P = 0.001), ATM--with grade of malignancy (P = 0.032), and PIK3CA--with PR-positive tumors (P = 0.047). HER2 overexpression correlated with age of diagnosis (P = 0.009), tumor size (P = 0.0004), and ER expression (P = 0.011). Univariate survival analysis showed that mutated p53 is an indicator for worse outcome (P = 0.041). Combination of two genetic abnormalities did not correlate with more aggressive carcinogenesis and worse overall survival. CONCLUSIONS: Our data indicated that p53, BRCA1, ATM, PIK3CA, and HER2 alterations specifically correlate with clinicopathological characteristics of Bulgarian patients with breast cancer. Of these genes, only mutated p53 showed significant, though not independent, negative effect on overall survival.
Kinross KM, etal., J Clin Invest. 2012 Feb;122(2):553-7. doi: 10.1172/JCI59309. Epub 2012 Jan 3.
Mutations in the gene encoding the p110α subunit of PI3K (PIK3CA) that result in enhanced PI3K activity are frequently observed in human cancers. To better understand the role of mutant PIK3CA in the initiation or prog
ression of tumorigenesis, we generated mice in which a PIK3CA mutation commonly detected in human cancers (the H1047R mutation) could be conditionally knocked into the endogenous Pik3ca locus. Activation of this mutation in the mouse ovary revealed that alone, Pik3caH1047R induced premalignant hyperplasia of the ovarian surface epithelium but no tumors. Concomitantly, we analyzed several human ovarian cancers and found PIK3CA mutations coexistent with KRAS and/or PTEN mutations, raising the possibility that a secondary defect in a co-regulator of PI3K activity may be required for mutant PIK3CA to promote transformation. Consistent with this notion, we found that Pik3caH1047R mutation plus Pten deletion in the mouse ovary led to the development of ovarian serous adenocarcinomas and granulosa cell tumors. Both mutational events were required for early, robust Akt activation. Pharmacological inhibition of PI3K/mTOR in these mice delayed tumor growth and prolonged survival. These results demonstrate that the Pik3caH1047R mutation with loss of Pten is enough to promote ovarian cell transformation and that we have developed a model system for studying possible therapies.
Takeshita T, etal., Oncotarget. 2017 Jun 14;8(32):52142-52155. doi: 10.18632/oncotarget.18479. eCollection 2017 Aug 8.
BACKGROUND: The measurement of ESR1 and PIK3CA mutations in plasma cell-free DNA (cfDNA) has been studied as a non-invasive method to quickly assess and monitor endocrine therapy (ET) resistant metastatic breast cancer (MBC) patients. METHODS: <
/b>The subjects of this retrospective study were a total of 185 plasma samples from 86 estrogen receptor-positive BC patients, of which 151 plasma samples were from 69 MBC patients and 34 plasma samples were from 17 primary BC (PBC) patients. We developed multiplex droplet digital PCR assays to verify the clinical significance of ESR1 and PIK3CA mutations both in a snapshot and serially in these patients. RESULTS: cfDNA ESR1 and PIK3CA mutations were found in 28.9% and 24.6 % of MBC patients, respectively. The relation between ESR1 or PIK3CA mutations and clinical features showed that ESR1 mutations occurred mostly in patients previously treated by ET, which was not the case for PIK3CA mutations. The analysis of the clinical impact of those mutations on subsequent lines of treatment for the 69 MBC patients revealed that both ESR1 and PIK3CA mutations detection were related to a shorter duration of ET effectiveness in univariate analysis but only for ESR1 mutations in multivariate analysis. The monitoring of cfDNA in a subset of 52 patients showed that loss of ESR1 mutations was related to a longer duration of response, which was not the case for PIK3CA mutations. CONCLUSIONS: We have demonstrated the clinical significance of on-treatment ESR1 mutations both in a snapshot and serially in comparison with PIK3CA mutations.
Lee H, etal., Asian Pac J Cancer Prev. 2015;16(11):4493-6.
Alterations in mitochondrial DNA (mtDNA) have been studied in various cancers. However, the clinical value of mtDNA copy number (mtCN) alterations in gastric cancer (GC) is poorly understood. In the present study, we investigated whether alterations in mtCNs might be associated with clinicopathologi
cal parameters in GC cases. mtCN was measured in 109 patients with GC by real-time PCR. Then, correlations with clinicopathological characteristics were analyzed. mtCN was elevated in 64.2% of GC tissues compared with paired, adjacent, non- cancerous tissue. However, the observed alterations in mtCN were not associated with any clinicopathological characteristics, including age, gender, TN stage, Lauren classification, lymph node metastasis, and depth of invasion. Moreover, Kaplan-Meier survival curves revealed that mtCN was not significantly associated with the survival of GC patients. In this study, we demonstrated that mtCN was not a significant marker for predicting clinical characteristics or prognosis in GC.
Zhang Q, etal., Oncotarget. 2016 Jul 19;7(29):46127-46141. doi: 10.18632/oncotarget.10060.
The tumor suppressor gene AT-rich interactive domain-containing protein 1A (ARID1A) was frequently mutated in cancers. The modulation mechanism of ARID1A for PI3K/AKT signaling in gastric cancer (GC) remains elusive. Here, we found that depletion of endogenous ARID1A enhanced the in vitro proliferat
ion, colony formation, cellular growth, nutrient uptake and in vivo xenograft tumor growth of GC cells. PI3K/AKT activation by ARID1A-silencing was profiled using a phospho-protein antibody array. The phosphorylation of PDK1, AKT, GSK3β and 70S6K, and the protein and mRNA expressions of PI3K and PDK1, were upregulated by ARID1A-silencing. Chromatin immunoprecipitation and luciferase reporter assay revealed that ARID1A-involved SWI/SNF complex inhibited PIK3CA and PDK1 transcription by direct binding to their promoters. Serial deletion mutation analyses revealed that the ARID1A central region containing the HIC1-binding domain, but not the ARID DNA-binding domain and the C-terminal domain, was essential for the inhibition of GC cell growth, PI3K/AKT pathway phosphorylation and its transcriptional modulation activity of PIK3CA and PDK1. The proliferation, cellular growth and glucose consumption of ARID1A-deficient GC cells were efficiently prohibited by allosteric inhibitors mk2206 and LY294002, which targeting AKT and PI3K, respectively. Both inhibitors also downregulated the phosphorylation of PI3K/AKT pathway in ARID1A-deficient GC cells. Such cells were sensitized to the treatment of LY294002, and AT7867, another inhibitor of AKT and p70S6K. The administration of LY294002 alone inhibited the in vivo growth of ARID1A- deficient GC cells in mouse xenograft model. Our study provides a novel insight into the modulatory function and mechanism of ARID1A in PI3K/AKT signaling in GC.
PURPOSE: CLAPO syndrome is a rare vascular disorder characterized by capillary malformation of the lower lip, lymphatic malformation predominant on the face and neck, asymmetry, and partial/generalized overgrowth. Here we tested the hypothesis that, although the genetic cause is not known
, the tissue distribution of the clinical manifestations in CLAPO seems to follow a pattern of somatic mosaicism. METHODS: We clinically evaluated a cohort of 13 patients with CLAPO and screened 20 DNA blood/tissue samples from 9 patients using high-throughput, deep sequencing. RESULTS: We identified five activating mutations in the PIK3CA gene in affected tissues from 6 of the 9 patients studied; one of the variants (NM_006218.2:c.248T>C; p.Phe83Ser) has not been previously described in developmental disorders. CONCLUSION: We describe for the first time the presence of somatic activating PIK3CA mutations in patients with CLAPO. We also report an update of the phenotype and natural history of the syndrome.
Ye S, etal., Medicine (Baltimore). 2016 Mar;95(9):e3003. doi: 10.1097/MD.0000000000003003.
Ovarian clear cell carcinoma (CCC) is a distinct histologic subtype with relatively poor survival. No prognostic or predictive molecular marker is currently available. Recent studies have shown that AT-rich interactive domain 1A (ARID1A) and phosphatidylinositol 3-kinase catalytic subunit alpha (... (more)
an style='font-weight:700;'>PIK3CA) mutations are common genetic changes in ovarian CCC. Hepatocyte nuclear factor-1beta (HNF-1beta) expression has been proven to be highly sensitive and specific for clear cell histology. However, the correlations between these biomarkers and clinicopathologic variables and survival outcomes are controversial. The immunohistochemical analysis for HNF-1beta, ARID1A, and PIK3CA was performed on a tissue microarray (TMA) consisting of 130 cases of ovarian CCC (237 tissue blocks) linked with clinical information. The immunostaining results were interpreted in a manner consistent with previous publications. The associations between biomarker expression and clinical and prognostic features were examined. All statistical analyses were conducted using 2-sided tests, and a value of P < 0.05 was considered significant. HNF-1beta was expressed in 92.8% of all primary ovarian tumors, while the loss of ARID1A and PIK3CA was noted in 56.2% and 45.0%, respectively. Early-stage tumors tended to have high levels of HNF-1beta immunoreactivity and expression of ARID1A (P = 0.02 and P = 0.03). Most patients (76.9%, 20/26) with concurrent endometriosis stained negative for ARID1A (P = 0.02). No relation was found between PIK3CA expression and clinical features. Low-level HNF-1beta expression and loss of ARID1A were more commonly observed in patients with tumor recurrence (P = 0.02 and P < 0.001). Antibody expression was not associated with platinum-based chemotherapy response. Patients with negative ARID1A expression had worse survival outcome in terms of both overall survival (OS) and progression-free survival (PFS) (P = 0.03 and P = 0.01, respectively). On the contrary, patients with high-level HNF-1beta were associated with good prognosis (P = 0.02 for OS and P = 0.01 for PFS). PIK3CA expression had no impact on survival. For univariate and multivariate analyses, only HNF-1beta expression seemed to be a prognostic factor for favorable OS (P = 0.04). The loss of ARID1A was correlated with late-stage and endometriosis-associated tumors. The measurement of ARID1A expression might be a method to predict the risk of recurrence. Among the 3 biomarkers, only high-level HNF-1beta expression proved to be a positive predictor for OS.
Kim DC, etal., APMIS. 2014 Oct;122(10):1001-6. doi: 10.1111/apm.12245. Epub 2014 Mar 28.
Hepatocellular carcinoma (HCC) is the fourth most common form of cancer in the Korean population, caused primarily by infection with either the Hepatitis B or C virus. Progression of this disease is frequently associated with mutations in either phosphoinositide-3-kinase, catalytic, alpha (PIK3CA
le='font-weight:700;'>PIK3CA) or hepatitis B virus X (HBx) gene. Previous studies have examined the frequency of PIK3CA mutations in HCC, although the clinical significance of these mutations has not been studied in a Korean population. In addition, HBx appears to play a key role in modulating a wide range of cellular functions, leading to HCC. In this study, we examined microdissected tumor samples from 50 HCC patients who underwent hepatectomy at Keimyung University Dongsan Medical Center. These patients were screened for mutations in PIK3CA and HBx to identify the clinical outcomes associated with these mutations. Exons 9 and 20 of PIK3CA and the entirety of HBx were screened for mutations by polymerase chain reaction and direct DNA sequencing. PIK3CA mutations were detected in 7 of 50 patients (14%). Among the 42 patients who were seropositive for hepatitis B, 17 (40.5%) had HBx mutations and 4 (9.52%) had mutations in PIK3CA. PIK3CA mutations were strongly correlated with tumor size. Patients harboring HBx mutations exhibited a longer time to recurrence; this difference was statistically significant not only in comparison with the PIK3CA mutation but also compared with those without any mutations. This result suggests a role for PIK3CA and HBx mutations as prognostic markers in HCC.
Li X, etal., Oncotarget. 2015 Apr 30;6(12):10102-15.
Activation of the PI3K and Yes-associated protein (Yap) signaling pathways has been independently reported in human hepatocellular carcinoma (HCC). However, the oncogenic interactions between these two cascades in hepatocarcinogenesis remain undetermined. To assess the consequences of the crosstalk
between the PI3K and Yap pathways along liver carcinogenesis, we generated a mouse model characterized by combined overexpression of activated mutant forms of PIK3CA (PIK3CAH1047R) and Yap (YapS127A) in the mouse liver using hydrodynamic transfection (PIK3CA/Yap). In addition, suppression of PI3K and Yap pathways was conducted in human HCC and cholangiocarcinoma (CCA) cell lines. We found that concomitant activation of PI3K and Yap pathways triggered rapid liver tumor development in mice. Histologically, tumors were pure HCC, CCA, or mixed HCC/CCA. At the molecular level, PIK3CA/Yap tumors were characterized by activation of the mTORC1/2, ERK/MAPK, and Notch pathways. Simultaneous activation of PI3K and Yap pathways frequently occurred in human liver tumor specimens and their combined suppression was highly detrimental for the growth of HCC and CCA cell lines. In conclusion, our study demonstrates the oncogenic cooperation between PI3K and Yap pathways along liver carcinogenesis. The PIK3CA/Yap mouse represents an important preclinical liver tumor model for the development of novel therapeutics against this malignancy.
Hadac JN, etal., Cancer Prev Res (Phila). 2015 Oct;8(10):952-61. doi: 10.1158/1940-6207.CAPR-15-0003. Epub 2015 Aug 14.
Human colorectal cancers often possess multiple mutations, including three to six driver mutations per tumor. The timing of when these mutations occur during tumor development and progression continues to be debated. More advanced lesions carry a greater number of driver mutations, indicating that
colon tumors might progress from adenomas to carcinomas through the stepwise accumulation of mutations following tumor initiation. However, mutations that have been implicated in tumor progression have been identified in normal-appearing epithelial cells of the colon, leaving the possibility that these mutations might be present before the initiation of tumorigenesis. We utilized mouse models of colon cancer to investigate whether tumorigenesis still occurs through the adenoma-to-carcinoma sequence when multiple mutations are present at the time of tumor initiation. To create a model in which tumors could concomitantly possess mutations in Apc, Kras, and Pik3ca, we developed a novel minimally invasive technique to administer an adenovirus expressing Cre recombinase to a focal region of the colon. Here, we demonstrate that the presence of these additional driver mutations at the time of tumor initiation results in increased tumor multiplicity and an increased rate of progression to invasive adenocarcinomas. These cancers can even metastasize to retroperitoneal lymph nodes or the liver. However, despite having as many as three concomitant driver mutations at the time of initiation, these tumors still proceed through the adenoma-to-carcinoma sequence.
Morrow CJ, etal., FEBS Lett. 2005 Sep 26;579(23):5123-8.
Recent studies have identified conserved missense mutations in PIK3CA, the gene encoding the catalytic phosphatidylinositol-3-kinase subunit p110alpha, in a variety of human cancers. Further investigation demonstrated that PIK3CA
span> mutations lead to increased basal phosphatidylinositol-3-kinase activity, promoting cell growth and invasion [Samuels, Y., Diaz, L.A., Jr., Schmidt-Kittler, O., Cummins, J.M., Delong, L., Cheong, I., Rago, C., Huso, D.L., Lengauer, C., Kinzler, K.W., Vogelstein, B. and Velculescu, V.E. (2005) Mutant PIK3CA promotes cell growth and invasion of human cancer cells. Cancer Cell 7, 561-573]. A panel of commonly used colorectal cancer cell lines was screened for these PIK3CA mutations. Constitutive and IGF-1-stimulated phosphatidylinositol-3-kinase activity, signal response and duration were assessed. In the assays used no differences distinguished cells carrying PIK3CA mutations indicating that these mutations did not significantly alter growth factor stimulated or steady state phosphatidylinositol-3-kinase activity in normal cell culture conditions.
Kang Z, etal., Mod Pathol. 2012 Aug;25(8):1160-8. doi: 10.1038/modpathol.2012.65. Epub 2012 Apr 20.
Extramammary Paget's disease is a rare cutaneous malignant neoplasm. The genetic and epigenetic mechanisms underlying its pathology remain unknown. In this study, we investigated the expression levels, and mutation and methylation status of a common tumor suppressor gene, deleted in liver cancer 1 (
DLC1), and an oncogene, PIK3CA, in tumor (n=132) and normal tissues (n=20) from unrelated patients. The presence of epigenetic and genetic lesions was then correlated to the patient pathology data to determine the potential role of these genes in extramammary Paget's disease etiology and progression. The DLC1 gene was found to be downregulated in 43 (33%) tumors, as compared with immunohistochemistry results from normal tissues. Methylation-sensitive, high-resolution melting analysis indicated that the DLC1 promoter was hypermethylated in 51 (39%) extramammary Paget's disease tumors. This hypermethylation was associated with significantly decreased DLC1 levels (P=0.011), and had a strong positive correlation with advanced age (P=0.002). PIK3CA mutations were detected by direct sequencing in 32 (24%) tumors, the majority of which were invasive. Furthermore, PIK3CA mutations significantly correlated with DLC1 hypermethylation. Thus, aberrant DLC1 methylation and PIK3CA mutations may have important roles in extramammary Paget's disease pathogenesis, and may represent potential molecular targets for therapy.
Rivière JB, etal., Nat Genet. 2012 Jun 24;44(8):934-40. doi: 10.1038/ng.2331.
Megalencephaly-capillary malformation (MCAP) and megalencephaly-polymicrogyria-polydactyly-hydrocephalus (MPPH) syndromes are sporadic overgrowth disorders associated with markedly enlarged brain size and other recognizable features. We performed exome sequencing in 3 families with MCAP or MPPH, and
our initial observations were confirmed in exomes from 7 individuals with MCAP and 174 control individuals, as well as in 40 additional subjects with megalencephaly, using a combination of Sanger sequencing, restriction enzyme assays and targeted deep sequencing. We identified de novo germline or postzygotic mutations in three core components of the phosphatidylinositol 3-kinase (PI3K)-AKT pathway. These include 2 mutations in AKT3, 1 recurrent mutation in PIK3R2 in 11 unrelated families with MPPH and 15 mostly postzygotic mutations in PIK3CA in 23 individuals with MCAP and 1 with MPPH. Our data highlight the central role of PI3K-AKT signaling in vascular, limb and brain development and emphasize the power of massively parallel sequencing in a challenging context of phenotypic and genetic heterogeneity combined with postzygotic mosaicism.
Sudhakar N, etal., J Biomol Struct Dyn. 2016;34(1):29-41. doi: 10.1080/07391102.2015.1007483. Epub 2015 Feb 13.
We examined 25 breast tumor samples for somatic mutations in exon 20 and exon 9 of PIK3CA gene in South Indian population. Genomic DNA was isolated and amplified for PIK3CA gene, followed by direct sequencing of purified pol
ymerase chain reaction products. We identified PI3K3CA mutations in 5 of 25 (20%), including four of the mutations in p.H1047R and one in p.H1047L. Nucleotide base substitution A to G (c.3140A > G) and A to T (c.3140A > T) results in p.H1047R and p.H1047L mutation in exon 20 of PIK3CA gene. We did not observe any mutation in exon 9 of PIK3CA gene. Furthermore, we investigated the effect of mutations on protein structure and function by the combination of sequence and structure-based in silico prediction methods. This determined the underlying relationship between the mutation and its phenotypic effects. Next step, we complemented by molecular dynamics simulation analysis (30 ns) of native and mutant structures that measured the effect of mutation on protein structure. The obtained results support that the application of computational methods helps predict the biological significance of mutations.
Ibarrola-Villava M, etal., Oncotarget. 2015 Sep 29;6(29):26935-45. doi: 10.18632/oncotarget.4775.
Genetic and epigenetic alterations play an important role in gastric cancer (GC) pathogenesis. Aberrations of the phosphatidylinositol-3-kinase signaling pathway are well described. However, emerging genes have been described such as, the chromatin remodeling gene ARID1A. Our aim was to determine
the expression levels of four GC-related genes, ARID1A, CDH1, cMET and PIK3CA, and 14 target-related microRNAs (miRNAs). We compared mRNA and miRNA expression levels among 66 gastric tumor and normal adjacent mucosa samples using quantitative real-time reverse transcription PCR. Moreover, ARID1A, cMET and PIK3CA protein levels were assessed by immunohistochemistry (IHC). Finally, gene and miRNAs associations with clinical characteristics and outcome were also evaluated. An increased cMET and PIK3CA mRNA expression was found in 78.0% (P = 2.20 x 10-5) and 73.8% (P = 1.00 x 10-3) of the tumors, respectively. Moreover, IHC revealed that cMET and PIK3CA expression was positive in 63.6% and 87.8% of the tumors, respectively. Six miRNAs had significantly different expression between paired-samples, finding five up-regulated [miR-223-3p (P = 1.65 x 10-6), miR-19a-3p (P = 1.23 x 10-4), miR-128-3p (P = 3.49 x 10-4), miR-130b-3p (P = 1.00 x 10-3) and miR-34a-5p (P = 4.00 x 10-3)] and one down-regulated [miR-124-3p (P = 0.03)]. Our data suggest that cMET, PIK3CA and target-related miRNAs play an important role in GC and may serve as potential targets for therapy.
The megalencephaly capillary malformation syndrome (MCAP, OMIM 602501) is known to be associated with mosaic mutations in PIK3CA occurring during embryogenesis. Standard sequencing technologies are relatively poor at indentifying sequence changes that only affe
ct a small percentage of cells, and the mutations are frequently not identified in lymphocyte DNA, with biopsies of the affected tissues often being required to detect mosaic mutations. Such invasive procedures are not always acceptable to parents. We describe the case of a patient in whom we were able to confirm a causative PIK3CA mutation, first found thorugh next-generation sequencing, in several tissue types including a secondary tooth. As part of this work, we were also able to begin validating dental tissue for potential use in genetic testing, as we achieved excellent DNA yields with minimal effort, even from deciduous teeth shed some years earlier.
Metastasis seriously affects the clinical outcome of renal cell carcinoma patients. Despite the approval of several targeted therapies that have led to an improvement in the progression-free survival rate for these patients, advanced and metastatic renal cell carcinoma remains difficult to treat. R
ecently, microRNAs have been found to play a critical role in the metastatic dissemination of renal cell carcinoma cells. In the present study, we found that miR-19a expression was significantly upregulated in metastatic clear cell renal carcinoma than that in adjacent and primary carcinoma tissues using qPCR and in situ hybridization experiments. In addition, the results were confirmed in renal carcinoma cell lines. miR-19a expression in the cell lines derived from a metastatic site was higher than that in cell lines derived from a primary site. By gain- and loss-of-function experiments, we found that miR-19a acted as an oncogenic miRNA regulating renal cancer cell proliferation, migration and invasion by directly targeting PIK3CA. Furthermore, we also explored the downstream molecules of miR-19a/PIK3CA signaling. We found that Notch signaling was induced by upregulation of miR-19a, and inactivation of Notch signaling attenuated the cell proliferation, migration and invasion promoted by miR-19a. Thus, we provide evidence demonstrating that downregulation of miR-19a may be therapeutically beneficial for metastatic renal carcinoma.
Liang M, etal., Drug Des Devel Ther. 2015 Jul 16;9:3607-16. doi: 10.2147/DDDT.S85525. eCollection 2015.
BACKGROUND: Despite advances in clinical therapies and technologies, the prognosis for patients with gastric cancer is still poor. The aim of this study is to investigate new predictive markers for prognosis of gastric cancer. METHODS: In this study, we evaluated the expression pattern of PIK3CA
e='font-weight:700;'>PIK3CA in 107 gastric cancer specimens and their adjacent nontumorous tissues. PIK3CA siRNA was synthesized and transfected into gastric cancer cell lines. Colony formation and MTT assays were employed to analyze the cell proliferation. PIK3CA expression was examined by using immunohistochemical analysis and Western blot assay. Transwell invasion assay was used to detect the invasion capability of the cells. Luciferase activity was examined by using 3'-untranslated region luciferase reporter assays. RESULTS: We observed that PIK3CA was significantly upregulated in gastric cancer tissues. High expression level of PIK3CA was detectable in 48 (44.86%) of the gastric cancer specimens, and correlated with poor prognosis. In addition, our study indicated that miR203 inhibits cell proliferation and invasion via directly targeting and suppressing the PIK3CA expression. MiR203 expression is downregulated in gastric cancer tissues. Moreover, low expression level of miR203 predicted poor prognosis of gastric patients and induced overexpression of PIK3CA. Our further study also reported that overexpression of miR203 inhibited phosphorylation of AKT, while cotransfection of PIK3CA reversed the effect of miR203. CONCLUSION: Our study suggested a miR203-PIK3CA-AKT signaling pathway in gastric cancer cells. This signaling pathway might play an important role in gastric cancer genesis and development.
HER2/neu gene amplification and PIK3CA driver mutations are common in uterine serous carcinoma (USC) and may represent ideal therapeutic targets against this aggressive variant of endometrial cancer. We examined the sensitivity to neratinib, taselisib, and the c
ombination of the two compounds in in vitro and in vivo experiments using PIK3CA-mutated and PIK3CA wild-type HER2/neu-amplified USC cell lines. Cell viability and cell-cycle distribution were assessed using flow-cytometry assays. Downstream signaling was assessed by immunoblotting. Preclinical efficacy of single versus dual inhibition was evaluated in vivo using two USC xenografts. We found both single-agent neratinib and taselisib to be active but only transiently effective in controlling the in vivo growth of USC xenografts harboring HER2/neu gene amplification with or without oncogenic PIK3CA mutations. In contrast, the combination of the two inhibitors caused a stronger and long-lasting growth inhibition in both USC xenografts when compared with single-agent therapy. Combined targeting of HER2 and PIK3CA was associated with a significant and dose-dependent increase in the percentage of cells in the G0-G1 phase of the cell cycle and a dose-dependent decline in the phosphorylation of S6. Importantly, dual inhibition therapy initiated after tumor progression in single-agent-treated mice was still remarkably effective at inducing tumor regression in both large PIK3CA and pan-ErbB inhibitor-resistant USC xenografts. Dual HER2/PIK3CA blockade may represent a novel therapeutic option for USC patients harboring tumors with HER2/neu gene amplification and mutated or wild-type PIK3CA resistant to chemotherapy.
Shi L, etal., Int J Clin Exp Pathol. 2015 Sep 1;8(9):10662-70. eCollection 2015.
MiRNA is a group of powerful short non-coding RNAs that suppress the expression of protein coding genes by targeting to the 3'UTRs of mRNAs. Some researchers have detected the miRNAs expression profile in tissue and blood samples of chronic obstructive pulmonary disease (COPD) patients recently. Sev
eral disturbed miRNAs were found to be related to COPD; however, the mechanisms were still well understood. In this study, we first detected the expression of 11 candidate miRNAs in the lung samples of COPD patients, non-COPD smokers and non-smock controls. We found that the expression of miR-181a, miR-203, miR-338, miR-1 and miR-199a was altered compared with control. Subsequently, we detected these five miRNAs expression in the blood samples of the participants. A significant higher expression of miR-203 was found in the blood samples of smokers and COPD patients. Predicted by bioinformatics tools and confirmed by luciferase assay and western blot, we demonstrated that TAK1 and PIK3CA are two direct targets of miR-203. Furthermore, we detected a lower p-IkappaBalpha and p-p65 level in the bronchial/tracheal epithelial cells from COPD patients compared with the cells from healthy controls, when stimulated by LPS. The concentration of TNF-alpha and IL-6 in the medium from bronchial/tracheal epithelial cells from COPD patients is also lower. Meanwhile, the miR-203 level was down-regulated significantly in the control cells, but non-significant change in the cells from COPD patients. miR-203 represses NF-kappaB signaling via targeting TAK1 and PI3KCA and miR-203 overexpression may contribute to the COPD initiation.
Tajima S, etal., Int J Clin Exp Pathol. 2015 May 1;8(5):5924-8. eCollection 2015.
Cystic lymphangioma, a lymphatic system malformation, is usually observed in infants and children and is rarely found in adults. It most commonly occurs in the cervicofacial region, followed by the axilla. Mediastinal cystic lymphangioma is rare, accounting for 1.8% of all mediastinal cysts. Herein,
we present an exceedingly rare adult case of mediastinal cystic lymphangioma that had increased in size over a 5-year period. Although fluid collection might be an alternative explanation for this increase in size, this lymphangioma might harbor a neoplastic nature related to the recently discovered PIK3CA mutation.
Böger C, etal., Ann Oncol. 2017 May 1;28(5):1005-1014. doi: 10.1093/annonc/mdx047.
Background: Recent whole-genome sequencing identified four molecular subtypes of gastric cancer (GC), of which the subgroup of Epstein-Barr virus-associated GC (EBVaGC) showed a significant enrichment of PIK3CA mutations. We here aimed to validate ind
ependently the enrichment of PIK3CA mutations in EBVaGC of a Central European GC cohort, to correlate EBV status with clinico-pathological patient characteristics and to test for a major issue of GC, intratumoral heterogeneity. Patients and methods: In a first step, 484 GCs were screened for EBV and PIK3CA hot spot mutations of exon 9/20 using EBER in situ hybridization and pyrosequencing, respectively. Secondly, an extended sequencing of PIK3CA also utilizing next generation sequencing was carried out in all EBVaGCs and 96 corresponding lymph node metastases. Results: Twenty-two GCs were EBER-positive, all being of latency type I. Intratumoral heterogeneity of EBER-positivity was found in 18% of EBVaGCs. Twenty-three GCs held PIK3CA mutations in hot spot regions of exon 9 or 20, being significantly more common in EBVaGCs (P < 0.001). Subsequent extended sequencing of PIK3CA of EBVaGCs showed that 14% harvested three to five different PIK3CA genotypes (including wildtype) in the same primary tumor, albeit in histologically and spatially distinct tumor areas, and that intratumoral heterogeneity of PIK3CA was also present in the corresponding lymph node metastases. Conclusions: Our findings unravel issues of tumor heterogeneity and illustrate that the assessment of the EBV status in tissue biopsies might carry the risk of sampling errors, which may significantly hamper adequate molecular tumor classification in a more clinical setting. Moreover, this is the first report of intratumoral heterogeneity of PIK3CA mutations in GC, and our findings lead to the conclusion that PIK3CA mutant and -wildtype tumor subclones are skilled to metastasize independently to different regional lymph nodes.
Seo AN, etal., Anticancer Res. 2019 Apr;39(4):2145-2154. doi: 10.21873/anticanres.13328.
BACKGROUND: Epstein-Barr virus (EBV)-associated gastric cancer (GC) is known to harbor a significant enrichment of of phosphatidylinositol 4, 5-biphosphate 3- kinase catalytic subunit alpha isoform (PIK3CA). Therefore, this study investigated the clin
ical relevance and prognostic role of PIK3CA mutations in patients with EBV-GC. MATERIALS AND METHODS: After reviewing 1,318 consecutive cases of surgically resected GC, 120 patients were identified as EBV-positive using EBV-encoded RNA in situ hybridization. PIK3CA mutations were identified in formalin-fixed and paraffin-embedded surgical specimens from 112 patients with EBV-GC with available tumor tissue samples. Real-time polymerase chain reaction was used to evaluate hot-spot mutations of exons 1, 4, 7, 9, and 20 of PIK3CA. RESULTS: Among the 112 patients, the frequency of PIK3CA mutations was 25.0% (n=28), and among the 28 patients harboring a PIK3CA mutation, most mutations were identified in exon 9 (n=21, 18.8%). The presence of PIK3CA mutation was also correlated with a higher T category (p<0.001) and N category (p<0.001), as well as the presence of perinueral invasion (p<0.001) and venous invasion (p<0.001). In a univariate analysis, PIK3CA mutation showed no association with overall survival (OS) (p=0.184) or disease-free survival (DFS) (p=0.150). Patients harboring exon 9 PIK3CA mutations exhibited a significantly shorter OS (p=0.023) and DFS (p=0.013) than the patients lacking an exon 9 PIK3CA mutation, yet without statistical significance in the multivariate analysis. Notably, exon 9 E542K mutation of PIK3CA was associated with the worst DFS (p=0.011). CONCLUSION: The current data show that PIK3CA mutations appear to play an important role in carcinogenesis and tumor aggressiveness in EBV-GC, and also support the concept that exon 9 mutation of PIK3CA is a prognostic indicator for predicting patient outcomes and a rationale for therapeutic targeting in EBV-GC.
Dong M, etal., Hum Pathol. 2016 Jul;53:25-34. doi: 10.1016/j.humpath.2016.02.007. Epub 2016 Mar 4.
As a special subtype of gastric carcinoma, Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC) has distinct clinicopathological features. The Cancer Genome Atlas Research Network revealed that EBVaGC also has distinct molecular features: PIK3CA mutati
ons, DNA hypermethylation, and JAK2, PD-L1, and PD-L2 amplification. Here, we evaluated PIK3CA, JAK2, PD-L1, and PD-L2 expression in 59 EBVaGC and 796 EBV-negative gastric carcinoma (EBVnGC) cases using immunohistochemistry and found that PIK3CA, JAK2, PD-L1, and PD-L2 were highly expressed in 75.9% and 48.8% (P<.001), 81.8% and 71.1% (P=.091), 92.5% and 84.8% (P=.132), and 98.1% and 89.7% (P=.049) of the EBVaGC and EBVnGC cases, respectively. However, the expression of PIK3CA, JAK2, PD-L1, or PD-L2 was not significantly associated with clinicopathological features or patient outcomes in EBVaGC. In contrast, in EBVnGC, high PIK3CA expression was significantly associated with indolent clinicopathological features and independently predicted better 5-year overall survival (57.8% versus 33.4%, P<.001). Our study indicated that the protein expression of the 4 characteristic molecules of EBVaGC was basically consistent with their genetic alterations, making them potential characteristic protein biomarkers and therapeutic targets of EBVaGC. The favorable impact of PIK3CA overexpression on survival found in this study gives us new insight into the clinical significance of PIK3CA in EBVnGC.
Lasota J, etal., Mod Pathol. 2016 Mar;29(3):275-82. doi: 10.1038/modpathol.2015.160. Epub 2016 Jan 22.
Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors usually driven by the mutational activation of receptor tyrosine kinases, KIT, or PDGFRA. Oncogenic activation of phosphatidylinositide-3-kinase (PI3K), a downstream effector in the KIT signaling pathway, has been identified in different
types of cancer, with the PI3K 110a subunit encoded by PIK3CA being a common mutational target. In this study, the mutational hotspot in the PIK3CA kinase domain encoded by exon 20 was evaluated in 529 imatinib-naive GISTs using PCR amplification and Sanger sequencing. Eight mutations (two co-existing in one tumor) were identified. Subsequently, The cobas PIK3CA Mutation Test was employed to evaluate mutational hotspots in exons 1, 4, 7, and 9 in 119 PIK3CA exon 20-wild type tumors. In two cases, mutations in exons 1 and 9 were identified. In one GIST, previously undetected by Sanger sequencing, the exon 20 mutation was discovered. Altogether, eight primary and two metastatic GISTs carried PIK3CA mutations. The size of primary PIK3CA-mutant GISTs was >=14¿cm (mean size 17¿cm), and mitotic activity varied from 0 to 72 per 50HPF (mean 5/50HPF). Follow-up data showed short survival in 6 of 7 studied cases. Detection of PIK3CA mutations in large or metastatic KIT-mutant GISTs may suggest that PIK3CA-mutant clones have a proliferative advantage during disease progression. Tyrosine kinase inhibitors have been successfully used in GIST treatment. However, resistance frequently develops due to secondary KIT mutations or activation of downstream to KIT signaling pathways, such as the PI3K/AKT/mTOR pathway. PIK3CA mutations similar to the ones detected in GISTs have been shown to cause such activation. Therefore, genotyping of PIK3CA in GISTs might help to pinpoint primary and metastatic tumors with the potential to develop resistance to tyrosine kinase inhibitors and guide therapy with PI3K inhibitors.
Shah S, etal., Oral Surg Oral Med Oral Pathol Oral Radiol. 2015 Nov;120(5):628-35. doi: 10.1016/j.oooo.2015.08.003. Epub 2015 Aug 11.
OBJECTIVE: The phosphatidylinositol 3-kinase (PIK3) genes, which code for heterodimeric lipid kinases, consist of a catalytic subunit, p110alpha (PIK3CA), which regulates cell proliferation, apoptosis, and metastasis. Recently, a high frequency of somatic mutat
ions was observed in the PIK3CA gene in various cancer types, including oral squamous cell carcinoma (OSCC). This study aimed to determine the frequency of oncogenic hotspot mutations in exons 9 and 20 of the PIK3CA gene and its correlation with the clinical characteristics of OSCC patients in an Indian population. STUDY DESIGN: We analyzed exons 9 and 20 of the PIK3CA gene using polymerase chain reaction (PCR) and direct genomic sequencing of 50 OSCC primary tumors. RESULTS: We observed two hotspot oncogenic mutations (E542 K, E545 K) in exon 9 and two synonymous mutations (A994 A, T1025 T) in exon 20. Moreover, we identified two single nucleotide polymorphisms (SNPs), rs114587137 (C>T) and rs17849071 (T>G), in intron 9 of the PIK3CA gene. Both oncogenic hotspot mutations were reported primarily in patients with advanced-stage cancer of the buccal mucosa. CONCLUSIONS: We have observed a 4% oncogenic mutation frequency of the PIK3CA gene, which plays a minor role in the development of OSCC in an Indian population.
Wan X, etal., Int J Clin Exp Pathol. 2015 Oct 1;8(10):13360-6. eCollection 2015.
PIK3CA has been shown to be involved in many malignant tumors. This study was designed to determine the expression level of PIK3CA in oral squamous cell carcinoma (OSCC) and the association of gene polymorphisms of PIK3CA
le='font-weight:700;'>PIK3CA with OSCC in Chinese population. The expression of PIK3CA was detected by real-time PCR in tumor and pericarcinomatous tissues of 10 OSCC patients. Nine single-nucleotide polymorphisms (SNPs) of PIK3CA (rs1607237, rs17849079, rs2677764, rs2699887, rs4855094, rs4975596, rs6443624, rs7651265 and rs7736074) in blood of 113 OSCC patients and 184 normal controls were genotyped using matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) assay. The gene expression of PIK3CA was significantly higher in tumor tissues of OSCC patients than that in pericarcinomatous tissues (P = 0.012). An increased frequency of the C allele of PIK3CA rs1607237 was observed in OSCC patients as compared with controls; However, the significance was lost after Bonferroni correction (P = 0.048, pc = 0.576). In further stratification analysis, although the frequencies of PIK3CA rs4975596 A allele in male patients and rs1607237 C allele in female patients were increased (P = 0.032, P = 0.020, respectively), the significance was also missing when Bonferroni correction was performed (P c = 0.384, (P c = 0.24, respectively). The prevalence of other SNPs of PIK3CA did not differ between OSCC patients and controls. The expression of PIK3CA was increased in OSCC tumors; however, none of the nine tested SNPs of PIK3CA was associated with susceptibility to OSCC in the studied population.
Hemifacial myohyperplasia (HFMH) is a rare cause of facial asymmetry exclusively involving facial muscles. The underlying cause and the mechanism of disease progression are unknown. Here, we identified a somatic gain-of-function mutation of PIK3CA in five pediat
ric patients with HFMH. To understand the physiopathology of muscle hypertrophy in this context, we created a mouse model carrying specifically a PIK3CA mutation in skeletal muscles. PIK3CA gain-of-function mutation led to striated muscle cell hypertrophy, mitochondria dysfunction, and hypoglycemia with low circulating insulin levels. Alpelisib treatment, an approved PIK3CA inhibitor, was able to prevent and reduce muscle hypertrophy in the mouse model with correction of endocrine anomalies. Based on these findings, we treated the five HFMH patients. All patients demonstrated clinical, esthetical, and radiological improvement with proof of target engagement. In conclusion, we show that HFMH is due to somatic alteration of PIK3CA and is accessible to pharmacological intervention.
Normanno N, etal., Ann Oncol. 2015 Aug;26(8):1710-4. doi: 10.1093/annonc/mdv176. Epub 2015 Apr 7.
BACKGROUND: Evidence suggests that metastatic colorectal carcinoma (mCRC) has a high level of intratumor heterogeneity. We carried out a quantitative assessment of tumor heterogeneity for KRAS, NRAS, BRAF and PIK3CA mutations, in order to assess potential clini
cal implications. PATIENTS AND METHODS: Tumor samples (n = 182) from the CAPRI-GOIM trial of first-line cetuximab + FOLFIRI in KRAS exon-2 wild-type mCRC patients were assessed by next-generation sequencing that allows quantitative assessment of mutant genes. Mutant allelic frequency was normalized for the neoplastic cell content and, assuming that somatic mutations usually affect one allele, the Heterogeneity Score (HS) was calculated by multiplying by 2 the frequency of mutant alleles in neoplastic cells. Therefore, HS virtually corresponds to the fraction of neoplastic cells carrying a specific mutation. RESULTS: The KRAS HS ranged between 12 and 260 with mean value of 87.1 and median value of 84.4, suggesting that in most CRC, the majority of neoplastic cells carry mutant KRAS. Similar findings were observed for NRAS (HS range 35.5-146.7; mean 102.8; median 117.1). In contrast, in BRAF (HS range 17.1-120; mean 54.8; median 54.3) and PIK3CA (HS range 14.3-120; mean 59.5; median 47.3) mutant cases, only a fraction of neoplastic cells seem to carry the mutant allele. The response rate was 70% in KRAS mutant patients with an HS <33 (low KRAS; n = 10) and 45.7% in KRAS HS >33 patients (high KRAS; n = 35); median progression-free survival were 7.97 and 8.37 months, respectively. Low-KRAS tumors had a higher frequency of additional mutations in PIK3CA when compared with high-KRAS (6/10 versus 8/35). CONCLUSIONS: KRAS and NRAS mutations are usually present in the majority of neoplastic cells, whereas BRAF and PIK3CA mutations often affect a limited fraction of transformed cells. Resistance to cetuximab in low-KRAS patients might be driven by the complex mutational profile rather than KRAS mutation load.
Hare LM, etal., Dev Biol. 2015 Aug 1;404(1):14-26. doi: 10.1016/j.ydbio.2015.04.022. Epub 2015 May 7.
The phosphoinositide 3-kinase (PI3K)/AKT signalling pathway regulates many cellular functions including proliferation, migration, survival and protein synthesis. Somatic mutations in PIK3CA, the gene encoding the p110α catalytic subunit of PI3K enzyme, are
commonly associated with many human cancers as well as recently being implicated in human overgrowth syndromes. However, it is not clear if such mutations can be inherited through the germline. We have used a novel mouse model with Cre recombinase (Cre)-conditional knock-in of the common H1047R mutation into the endogenous Pik3ca gene. Heterozygous expression of the Pik3ca(H1047R) mutation in the developing mouse embryo resulted in failed 'turning' of the embryo and disrupted vascular remodelling within the embryonic and extraembryonic tissues, leading to lethality prior to E10. As vascular endothelial growth factor A (VEGF-A) signalling was disrupted in these embryos, we used Cre under the control of the Tie2 promoter to target the Pik3ca(H1047R) mutation specifically to endothelial cells. In these embryos turning occurred normally but the vascular remodelling defects and embryonic lethality remained, likely as a result of endothelial hyperproliferation. Our results confirm the lethality associated with heterozygous expression of the Pik3ca(H1047R) mutation during development and likely explain the lack of inherited germline PIK3CA mutations in humans.
Jacot W, etal., BMC Cancer. 2015 Dec 18;15:986. doi: 10.1186/s12885-015-1977-3.
BACKGROUND: Triple negative breast cancers (TNBC) are a more aggressive subset of breast cancer. A better understanding of its biology could allow the rational development of targeted therapies. METHODS: We extensively analyzed the EGFR/PI3K/PTEN axis in a large, homogeneous population of TNBC to he
lp defining the putative role of anti-EGFR and -PI3K targeted therapies in this setting. EGFR gene amplification, EGFR protein expression, PIK3CA and PTEN gene alterations (two members of EGFR downstream pathways) and their clinicopathological and prognostic implications were analyzed in 204 TNBC samples from European patients. RESULTS: EGFR amplification was detected in 18 of the 204 TNBC specimens (8.9 %) and was significantly associated with higher EGFR protein levels. Fourteen PIK3CA mutations were identified in exon 9 (6.7 %), and 17 in exon 20 (8.3 %). PIK3CA mutations, especially in exon 9, were significantly associated with grade I-II tumors. PTEN deletions were detected in 43 samples (21.50 %) and were significantly associated with grade III tumors (p < 0.001). Univariate analysis showed a significant association between relapse-free survival (RFS), T and N stage and exon 9 PIK3CA mutations. Overall survival was significantly associated with T stage, N stage and adjuvant chemotherapy, which was administered to 70.3 % of patients. In multivariate analyses, T stage, N stage, presence of exon 9 PIK3CA mutations and high EGFR protein level were independent poor prognostic factors for RFS, while adjuvant chemotherapy was associated with a better outcome. CONCLUSIONS: High EGFR protein expression and exon 9 PIK3CA activating mutations are independent prognostic factors in TNBC. The efficacy of anti-PI3K targeted therapies needs to be evaluated in this setting.
BACKGROUND: KRAS is an EGFR effector in the RAS/RAF/ERK cascade that is mutated in about 40% of metastatic colorectal cancer (mCRC). Activating mutations in codons 12 and 13 of the KRAS gene are the only established negative predictors of response to anti-EGFR therapy and patients whose tumors harbo
r such mutations are not candidates for therapy. However, 40 to 60% of wild-type cases do not respond to anti-EGFR therapy, suggesting the involvement of other genes that act downstream of EGFR in the RAS-RAF-MAPK and PI3K-AKT pathways or activating KRAS mutations at other locations of the gene. METHODS: DNA was obtained from a consecutive series of 201 mCRC cases (FFPE tissue), wild-type for KRAS exon 2 (codons 12 and 13). Mutational analysis of KRAS (exons 3 and 4), BRAF (exons 11 and 15), and PIK3CA (exons 9 and 20) was performed by high resolution melting (HRM) and positive cases were then sequenced. RESULTS: One mutation was present in 23.4% (47/201) of the cases and 3.0% additional cases (6/201) had two concomitant mutations. A total of 53 cases showed 59 mutations, with the following distribution: 44.1% (26/59) in KRAS (13 in exon 3 and 13 in exon 4), 18.6% (11/59) in BRAF (two in exon 11 and nine in exon 15) and 37.3% (22/59) in PIK3CA (16 in exon 9 and six in exon 20). In total, 26.4% (53/201) of the cases had at least one mutation and the remaining 73.6% (148/201) were wild-type for all regions studied. Five of the mutations we report, four in KRAS and one in BRAF, have not previously been described in CRC. BRAF and PIK3CA mutations were more frequent in the colon than in the sigmoid or rectum: 20.8% vs. 1.6% vs. 0.0% (P=0.000) for BRAF and 23.4% vs. 12.1% vs. 5.4% (P=0.011) for PIK3CA mutations. CONCLUSIONS: About one fourth of mCRC cases wild-type for KRAS codons 12 and 13 present other mutations either in KRAS, BRAF, or PIK3CA, many of which may explain the lack of response to anti-EGFR therapy observed in a significant proportion of these patients.
Simi L, etal., Am J Clin Pathol. 2008 Aug;130(2):247-53. doi: 10.1309/LWDY1AXHXUULNVHQ.
High-resolution melting analysis (HRMA) provides a valid approach to efficiently detect DNA genetic and somatic mutations. In this study, HRMA was used for the screening of 116 colorectal cancers (CRCs) to detect hot-spot mutations in the KRAS and BRAF oncogenes. Mutational hot spots on the PIK3CA
tyle='font-weight:700;'>PIK3CA gene, exons 9 and 20, were also screened. Direct sequencing was used to confirm and characterize HRMA results. HRMA revealed abnormal melting profiles in 65 CRCs (56.0%), 16 of them harboring mutations in 2 different genes simultaneously. The frequency of mutations was 17.2% for PIK3CA (11.2% in exon 9 and 6.0% in exon 20), 43.1% for KRAS exon 2, and 9.5% in exon 15 of the BRAF gene. We found a significant association between PIK3CA and KRAS mutations (P = .008), whereas KRAS and BRAF mutations were mutually exclusive (P = .001). This report describes a novel approach for the detection of PIK3CA somatic mutations by HRMA.
Eng J, etal., J Thorac Oncol. 2015 Dec;10(12):1713-9. doi: 10.1097/JTO.0000000000000671.
INTRODUCTION: In patients with epidermal growth factor receptor (EGFR)-mutant or KRAS-mutant lung adenocarcinomas, the prognostic impact of a concurrent PIK3CA mutation remains unclear. Although preclinical data suggest that sensitivity to EGFR tyrosine kinase
inhibition (TKI) is decreased in EGFR-mutant lung cancers also harboring a PIK3CA mutation, this interaction has not been explored clinically. METHODS: Patients with lung adenocarcinomas harboring a PIK3CA mutation concurrent with a separate driver mutation were identified through mutational hotspot testing, multiplex sizing assays, and fluorescence in situ hybridization. Overall survival and outcomes with EGFR TKI monotherapy (EGFR-mutant) were estimated using Kaplan-Meier methods and compared between double-mutant (EGFR-mutant or KRAS-mutant, concurrent PIK3CA-mutant) and single-mutant patients (EGFR-mutant or KRAS-mutant, PIK3CA wild-type) using log-rank tests. RESULTS: In EGFR-mutant and KRAS-mutant lung cancers, a concurrent PIK3CA mutation was associated with a decrease in median overall survival: 18 versus 33 months (EGFR double mutant, n = 10 versus single mutant, n = 43, p = 0.006), and 9 versus 16 months (KRAS double mutant, n = 16 versus single mutant, n = 47, p = 0.020). In EGFR-mutant lung cancers, a concurrent PIK3CA mutation did not impact benefit from EGFR TKI monotherapy. Single versus double mutant: objective response rate, 83% (n = 29) versus 62% (n = 6, p = 0.80); median time to progression, 11 (n = 29) versus 8 months (n = 6, p = 0.84); and median duration of TKI therapy, 15 (n = 32) versus 15 months (n = 10, p = 0.65). CONCLUSION: A concurrent PIK3CA mutation is a poor prognostic factor in patients with advanced EGFR-mutant or KRAS-mutant lung adenocarcinomas. There was no evidence that clinical benefit from EGFR TKI monotherapy is affected by a concurrent PIK3CA mutation in EGFR-mutant lung cancers.
Kumar DT and Doss CG, Adv Protein Chem Struct Biol. 2016;102:267-97. doi: 10.1016/bs.apcsb.2015.09.008. Epub 2015 Oct 29.
Oncogenic mutations in phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) are the most frequently reported in association with various forms of cancer. Several studies have reported the significance of hotspot mutations in a cataly
tic subunit of PIK3CA in association with breast cancer. Mutations are frequently observed in the highly conserved region of the kinase domain (797-1068 amino acids) of PIK3CA are activating or gain-of-function mutations. Mutation in codon 1047 occurs in the C-terminal region of the kinase domain with histidine (H) replaced by arginine (R), lysine (L), and tyrosine (Y). Pathogenicity and protein stability predictors PhD-SNP, Align GVGD, HANSA, iStable, and MUpro classified H1047R as highly deleterious when compared to H1047L and H1047Y. To explore the inhibitory activity of Wortmannin toward PIK3CA, the three-dimensional structure of the mutant protein was determined using homology modeling followed by molecular docking and molecular dynamics analysis. Docking studies were performed for the three mutants and native with Wortmannin to measure the differences in their binding pattern. Comparative docking study revealed that H1047R-Wortmannin complex has a higher number of hydrogen bonds as well as the best binding affinity next to the native protein. Furthermore, 100 ns molecular dynamics simulation was initiated with the docked complexes to understand the various changes induced by the mutation. Though Wortmannin was found to nullify the effect of H1047R over the protein, further studies are required for designing a better compound. As SNPs are major genetic variations observed in disease condition, personalized medicine would provide enhanced drug therapy.
Zhou L, etal., Med Oncol. 2016 Apr;33(4):32. doi: 10.1007/s12032-016-0745-9. Epub 2016 Feb 29.
The oncogenic hallmarks of pancreatic cancer (PC), such as the KRAS, BRAF, and PIK3CA mutations, have been widely investigated. However, almost all of the previous studies were limited by small sample sizes. In addition, previous data on the KRAS mutation and cl
inical outcomes in PC remain inconclusive. To clarify these data, we examined the mutation status of 126 PC patients and its relationship to clinical outcome. The frequencies of KRAS, BRAF, and PIK3CA mutations were determined from a non-biased database of 126 resected PCs and a high-throughput pyrosequencing assay. KRAS mutations were detected in 109 (86.5 %) of the 126 cases; the most common mutation was c.34G > T (p.G12C), which was present in 80 tumors, followed by c.35G > T (p.G12V) in 52 tumors. The KRAS mutation was not associated with any clinical or pathological features (p > 0.05 in all cases). In addition, the KRAS mutation was unrelated to overall survival (log rank p = 0.21) and cancer-specific survival (log rank p = 0.27). Importantly, the influence of KRAS mutation on patient outcome was not modified by any of the clinical or pathological variables (p for all interactions >0.05). Only one PIK3CA mutation (0.8 %) was detected on exon 9 RS3 (c.1633G > A, p.E545K). The BRAF mutation was not detected in PC. KRAS mutations appear to be unrelated to clinical outcome in PC. BRAF and PIK3CA mutations were extremely rare in PC, suggesting that they play a limited role in PC development.
Ampullary adenocarcinomas (A-ACs) are rare malignancies with considerable importance because of their high curable resection rate and improved survival rate among periampullary cancers. The RAS-RAF-MAPK pathway is involved in the development of A-ACs and is a potential therapeutic target. However, m
olecular profiles of A-ACs and their prognostic impact are poorly understood. Peptide nucleic acid-mediated polymerase chain reaction clamping and Mutyper were used to detect KRAS, BRAF, and PIK3CA mutations in 62 paraffinized samples of A-ACs. Of 62 A-ACs, 30.6% had KRAS mutations, but no BRAF mutations and low frequency (1.6%) of PIK3CA mutation were detected. KRAS mutation was correlated with poor tumor differentiation and was a predictor of shorter recurrence-free survival period in overall A-ACs, whereas the prognosis according to the histologic subtypes was not affected by KRAS mutation. Lymph node metastasis was an independent prognostic factor of poor overall survival. Intestinal- and pancreatobiliary-type A-ACs had similar prognosis. Intestinal- and pancreatobiliary-type A-ACs had different prognostic factors; tumor differentiation and lymph node metastasis strongly predicted overall survival and recurrence-free survival in pancreatobiliary-type tumors, respectively, whereas no independent prognostic factors were demonstrated for intestinal-type tumors. Low incidence of KRAS mutations and their strong prognostic value in A-ACs may suggest the potential of survival benefit depending on the epidermal growth factor receptor-targeted therapy. Much lower frequencies of BRAF and PIK3CA mutations may suggest that they do not play a major role in the tumorigenesis of A-ACs. Different therapeutic protocols should be considered for treating pancreatobiliary- and intestinal-type A-ACs.
Zhang J, etal., Sci Rep. 2015 Dec 22;5:18678. doi: 10.1038/srep18678.
Mutations in genes such as KRAS, NRAS, BRAF and PIK3CA have become an important part of colorectal carcinoma evaluation. The aim of this study was to screen for mutations in these genes in Chinese patients with colorectal cancer (CRC) and to explore their correl
ations with certain clinicopathological parameters. We tested mutations in the KRAS (exons 2, 3 and 4), NRAS (exons 2, 3 and 4), PIK3CA (exon 20) and BRAF (exon 15) genes using reverse transcriptase-polymerase chain reaction (RT-PCR) and Sanger sequencing in a large cohort of 1,110 Chinese CRC patients who underwent surgical resection at one of three major teaching hospitals located in different regions of China. The prevalence rates of KRAS, NRAS, BRAF and PIK3CA mutations were 45.4%, 3.9%, 3.1% and 3.5%, respectively. Mutant KRAS was associated with the mucinous subtype and greater differentiation, while mutant BRAF was associated with right-sided tumors and poorer differentiation. Our results revealed differences in the genetic profiles of KRAS, NRAS, PIK3CA and BRAF at mutation hotspots between Chinese CRC patients and those of Western countries, while some of these gene features were shared among patients from other Asian countries.
Lindhurst MJ, etal., Nat Genet. 2012 Jun 24;44(8):928-33. doi: 10.1038/ng.2332.
The phosphatidylinositol 3-kinase (PI3K)-AKT signaling pathway is critical for cellular growth and metabolism. Correspondingly, loss of function of PTEN, a negative regulator of PI3K, or activating mutations in AKT1, AKT2 or AKT3 have been found in distinct disorders featuring overgrowth or hypoglyc
emia. We performed exome sequencing of DNA from unaffected and affected cells from an individual with an unclassified syndrome of congenital progressive segmental overgrowth of fibrous and adipose tissue and bone and identified the cancer-associated mutation encoding p.His1047Leu in PIK3CA, the gene that encodes the p110α catalytic subunit of PI3K, only in affected cells. Sequencing of PIK3CA in ten additional individuals with overlapping syndromes identified either the p.His1047Leu alteration or a second cancer-associated alteration, p.His1047Arg, in nine cases. Affected dermal fibroblasts showed enhanced basal and epidermal growth factor (EGF)-stimulated phosphatidylinositol 3,4,5-trisphosphate (PIP(3)) generation and concomitant activation of downstream signaling relative to their unaffected counterparts. Our findings characterize a distinct overgrowth syndrome, biochemically demonstrate activation of PI3K signaling and thereby identify a rational therapeutic target.
Hafner C, etal., Proc Natl Acad Sci U S A. 2007 Aug 14;104(33):13450-4. doi: 10.1073/pnas.0705218104. Epub 2007 Aug 2.
Activating mutations of the p110 alpha subunit of PI3K (PIK3CA) oncogene have been identified in a broad spectrum of malignant tumors. However, their role in benign or preneoplastic conditions is unknown. Activating FGF receptor 3 (FGFR3) mutations are common in
benign skin lesions, either as embryonic mutations in epidermal nevi (EN) or as somatic mutations in seborrheic keratoses (SK). FGFR3 mutations are also common in low-grade malignant bladder tumors, where they often occur in association with PIK3CA mutations. Therefore, we examined exons 9 and 20 of PIK3CA and FGFR3 hotspot mutations in EN (n = 33) and SK (n = 62), two proliferative skin lesions lacking malignant potential. Nine of 33 (27%) EN harbored PIK3CA mutations; all cases showed the E545G substitution, which is uncommon in cancers. In EN, R248C was the only FGFR3 mutation identified. By contrast, 10 of 62 (16%) SK revealed the typical cancer-associated PIK3CA mutations E542K, E545K, and H1047R. The same lesions displayed a wide range of FGFR3 mutations. Corresponding unaffected tissue was available for four EN and two mutant SK: all control samples displayed a WT sequence, confirming the somatic nature of the mutations found in lesional tissue. Forty of 95 (42%) lesions showed at least one mutation in either gene. PIK3CA and FGFR3 mutations displayed an independent distribution; 5/95 lesions harbored mutations in both genes. Our findings suggest that, in addition to their role in cancer, oncogenic PIK3CA mutations contribute to the pathogenesis of skin tumors lacking malignant potential. The remarkable genotype-phenotype correlation as observed in this study points to a distinct etiopathogenesis of the mutations in keratinocytes occuring either during fetal development or in adult life.
Du L, etal., Oncogene. 2016 Sep 1;35(35):4641-52. doi: 10.1038/onc.2016.1. Epub 2016 Feb 15.
Head and neck squamous cell carcinoma (HNSCC) patients have a poor prognosis, with invasion and metastasis as major causes of mortality. The phosphatidylinositol 3-kinase (PI3K) pathway regulates a wide range of cellular processes crucial for tumorigenesis, and PIK3CA
/span> amplification and mutation are among the most common genetic alterations in human HNSCC. Compared with the well-documented roles of the PI3K pathway in cell growth and survival, the roles of the PI3K pathway in tumor invasion and metastasis have not been well delineated. We generated a PIK3CA genetically engineered mouse model (PIK3CA-GEMM) in which wild-type PIK3CA is overexpressed in head and neck epithelium. Although PIK3CA overexpression alone was not sufficient to initiate HNSCC formation, it significantly increased tumor susceptibility in an oral carcinogenesis mouse model. PIK3CA overexpression in mouse oral epithelium increased tumor invasiveness and metastasis by increasing epithelial-mesenchymal transition and by enriching a cancer stem cell phenotype in tumor epithelial cells. In addition to these epithelial alterations, we also observed marked inflammation in tumor stroma. AKT is a central signaling mediator of the PI3K pathway. However, molecular analysis suggested that progression of PIK3CA-driven HNSCC is facilitated by 3-phosphoinositide-dependent protein kinase (PDK1) and enhanced transforming growth factor beta (TGFbeta) signaling rather than by AKT. Examination of human HNSCC clinical samples revealed that both PIK3CA and PDK1 protein levels correlated with tumor progression, highlighting the significance of this pathway. In summary, our results offer significant insight into how PIK3CA overexpression drives HNSCC invasion and metastasis, providing a rationale for targeting PI3K/PDK1 and TGFbeta signaling in advanced HNSCC patients with PIK3CA amplification.
Baba Y, etal., Cancer. 2011 Apr 1;117(7):1399-408. doi: 10.1002/cncr.25630. Epub 2010 Nov 8.
BACKGROUND: AKT (AKT1, AKT2, and AKT3) was a downstream effector of phosphatidylinositide-3-kinase (PI3K) and played crucial roles in protein synthesis, cellular metabolism, survival, and proliferation. The PI3K/AKT pathway was commonly activated in human cancers and was recognized as a p
otential target for anticancer therapy. Nonetheless, clinical, molecular, or prognostic features of AKT-activated colon cancer remained uncertain. METHODS: Using a database of 717 colon and rectal cancers in the Nurses' Health Study and the Health Professionals Follow-up Study, Ser473 phosphorylated AKT (p-AKT) expression was detected in 448 (62%) tumors by immunohistochemistry. Cox proportional hazards model was used to compute mortality hazards ratio (HR), adjusting for clinical and tumoral features, including PIK3CA, KRAS, BRAF, microsatellite instability (MSI), CpG island methylator phenotype (CIMP), LINE-1 methylation, TP53 (p53), and FASN (fatty acid synthase). RESULTS: Tumor p-AKT expression was associated with PIK3CA mutation (odds ratio [OR], 1.77; 95% confidence interval [CI], 1.12-2.80; P = .015). p-AKT expression was significantly associated with longer colorectal cancer-specific survival in Kaplan-Meier analysis (log-rank P = .0005), univariate Cox regression (HR, 0.62; 95% CI, 0.47-0.82; P = .0006) and multivariate analysis (adjusted HR, 0.75; 95% CI, 0.56-0.99; P = .048) adjusting for clinical and molecular variables including PIK3CA, MSI, CIMP and LINE-1 hypomethylation. p-AKT expression was inversely associated with high stage (III-IV) (adjusted OR, 0.63; 95% CI, 0.45-0.88, P = .0071). CONCLUSIONS: p-AKT expression in colorectal cancer is associated with low stage and good prognosis. p-AKT may serve as a tissue biomarker to identify patients with superior prognosis and a possible therapeutic target (analogous to estrogen receptor ESR1 in breast cancer).
Lee H, etal., Int J Med Sci. 2015 Apr 27;12(4):349-53. doi: 10.7150/ijms.11281. eCollection 2015.
Colorectal cancer is a heterogeneous disorder than arises via multiple distinct pathways, from tubular adenomas (TAs) and sessile serrated adenomas (SSAs), which are clinically, morphologically, and molecularly different. We examined PIK3CA amplification in colo
rectal precancerous legions, including TAs and SSAs. DNA was isolated from paired normal and tumoral tissues in 64 TAs and 32 SSAs. PIK3CA amplification, KRAS mutation, and BRAF mutation were analyzed by real-time PCR and pyrosequencing. PIK3CA amplification was found in 25% of TAs and 9.4% of SSAs, respectively. KRAS and BRAF mutations were mutually exclusive in both TAs and SSAs. In TAs, PIK3CA amplification was associated with left side and it was mutually exclusive with KRAS mutation. These results suggest that PIK3CA amplification may be early and important event in colorectal carcinogenesis and may drive the development of left-side TAs independently with KRAS mutation.
Mutations in the PIK3CA gene have recently been reported in different human neoplasms, including breast cancer. This paper reports the results of a systematic analysis of PIK3CA mutations in different histological types of b
reast carcinoma. One hundred and eighty invasive breast carcinomas, comprising 74 ductal, 56 lobular, 22 mucinous, 20 medullary, and eight papillary, were selected on the basis of their histological type in a consecutive series of 780 breast cancers. Exons 1-20 of the PIK3CA gene were subjected to SSCP analysis followed by direct sequencing. PIK3CA mutations were observed in 46 (26%) of the 180 tumours examined: 23 (50%) mutations were located in exon 9, and 23 (50%) in exon 20. Mutations were frequent in lobular (46%), less frequent in ductal (22%), and uncommon in medullary (10%), mucinous (5%), and papillary tumours (12%) (p = 0.0002). Mutations in exon 9 were more frequent in lobular carcinomas (30% of cases) than in the other histological types (less than 5% of cases) (p = 0.00014). No significant differences were observed in the distribution of mutations in exon 20. There was no significant correlation between PIK3CA mutations and other clinicopathological and biological variables, including age, tumour size, lymph node metastases, oestrogen receptor (ER) status, progesterone receptor (PgR) status, p53 gene mutations, and p53 protein expression. The findings indicate that in invasive breast carcinomas, PIK3CA alterations are mainly present in lobular and ductal tumours, whereas the other histological types, known to be associated with a favourable prognosis, show a very low incidence of PIK3CA mutations.
Phipps AI, etal., Cancer Epidemiol Biomarkers Prev. 2015 Jul;24(7):1046-51. doi: 10.1158/1055-9965.EPI-15-0204. Epub 2015 May 20.
BACKGROUND: Approximately 10% to 20% of colorectal cancers exhibit somatic mutations in the phosphoinositide-3-kinase, catalytic, alpha polypeptide gene (PIK3CA). We evaluated the relationship of PIK3CA mutation status in co
lorectal cancer with race/ethnicity, colorectal cancer survival, and other patient and tumor factors. METHODS: This study comprised 377 racial/ethnic minorities with incident invasive colorectal cancer, enrolled in the Colon Cancer Family Registry via population-based cancer registries. Tumor specimens were tested for PIK3CA mutations in exon 9 and 20 hotspots, BRAF p.V600E mutations, and DNA mismatch repair (MMR). In logistic regression models, we evaluated the association between PIK3CA mutation status and race/ethnicity, overall, and by mutation site. Using Cox regression, we evaluated the association between PIK3CA mutation status and survival after colorectal cancer diagnosis. RESULTS: PIK3CA mutations were detected in 42 cases (11%), with a similar prevalence across racial/ethnic groups. Individuals with PIK3CA-mutated colorectal cancer were significantly more likely than those with PIK3CA-wildtype disease to have proximal colon cancer, MMR-deficient tumors, and a germline MMR mutation (P PIK3CA and overall survival (HR, 0.77; 95% confidence interval, 0.43-1.39). CONCLUSIONS: The prevalence of PIK3CA mutation status in colorectal cancer does not differ according to race/ethnicity, but may vary according to other relevant clinicopathologic and etiologic factors, including germline MMR mutation status, tumor MMR status, and tumor site. IMPACT: These findings underscore the importance of PIK3CA mutation status in colorectal cancer epidemiology and provide evidence that the prevalence of such mutations is similar across several racial/ethnic groups.
Beca F, etal., Mod Pathol. 2020 Aug;33(8):1518-1526. doi: 10.1038/s41379-020-0511-6. Epub 2020 Mar 2.
Angiosarcoma (AS) is the most frequent primary sarcoma of the breast but nevertheless remains uncommon, accounting for <0.05% of breast malignancies. Secondary mammary AS arise following radiation therapy for breast cancer, in contrast to primary AS which occur sporadically. Essentially all show agg
ressive clinical behavior independent of histologic grade and most are treated by mastectomy. MYC amplification is frequently identified in radiation-induced AS but only rarely in primary mammary AS (PMAS). As a heterogeneous group, AS from various anatomic sites have been shown to harbor recurrent alterations in TP53, MAP kinase pathway genes, and genes involved in angiogenic signaling including KDR (VEGFR2) and PTPRB. In part due to its rarity, the pathogenesis of PMAS has not been fully characterized. In this study, we examined the clinical, pathologic, and genomic features of ten cases of PMAS, including one patient with bilateral disease. Recurrent genomic alterations were identified in KDR (70%), PIK3CA/PIK3R1 (70%), and PTPRB (30%), each at higher frequencies than reported in AS across all sites. Six tumors harbored a KDR p.T771R hotspot mutation, and all seven KDR-mutant cases showed evidence suggestive of biallelism (four with loss of heterozygosity and three with two aberrations). Of the seven tumors with PI3K alterations, six harbored pathogenic mutations other than in the canonical PIK3CA residues which are most frequent in breast cancer. Three AS were hypermutated (>=10 mutations/megabase (Mb)); hypermutation was seen concurrent with KDR or PIK3CA mutations. The patient with bilateral disease demonstrated shared alterations, indicative of contralateral metastasis. No MYC or TP53 aberrations were detected in this series. Immunohistochemistry for VEGFR2 was unable to discriminate between KDR-mutant tumors and benign vascular lesions of the breast. These findings highlight the underrecognized frequency of KDR and PIK3CA mutation in PMAS, and a significant subset with hypermutation, suggesting a pathogenesis distinct from other AS.
BACKGROUND: The PI3K-AKT pathway is frequently activated in breast cancer. PIK3CA mutations are most frequently found in the helical (exon 9) and kinase (exon 20) domains of this protein. The aim of the present study was to examine the role of different types
of PIK3CA mutations in combination with molecular biomarkers related to PI3K-AKT signaling in patients with early breast cancer. METHODS: Tumor tissue samples from 1008 early breast cancer patients treated with adjuvant chemotherapy in two similar randomized trials of HeCOG were examined. Tumors were subtyped with immunohistochemistry (IHC) and FISH for ER, PgR, Ki67, HER2 and androgen receptor (AR). PIK3CA mutations were analyzed by Sanger sequencing (exon 20) and qPCR (exon 9) (Sanger/qPCR mutations). In 610 cases, next generation sequencing (NGS) PIK3CA mutation data were also available. PIK3CA mutations and PTEN protein expression (IHC) were analyzed in luminal tumors (ER and/or PgR positive), molecular apocrine carcinomas (MAC; ER/PgR negative / AR positive) and hormone receptor (ER/PgR/AR) negative tumors. RESULTS: PIK3CA mutations were detected in 235/1008 tumors (23%) with Sanger/qPCR and in 149/610 tumors (24%) with NGS. Concordance between the two methods was good with a Kappa coefficient of 0.76 (95% CI 0.69-0.82). Lobular histology, low tumor grade and luminal A tumors were associated with helical domain mutations (PIK3CAhel), while luminal B with kinase domain mutations (PIK3CAkin). The overall incidence of PIK3CA mutations was higher in luminal as compared to MAC and hormone receptor negative tumors (p = 0.004). Disease-free and overall survival did not significantly differ with respect to PIK3CA mutation presence and type. However, a statistically significant interaction between PIK3CA mutation status and PTEN low protein expression with regard to prognosis was identified. CONCLUSIONS: The present study did not show any prognostic significance of specific PIK3CA mutations in a large group of predominantly lymph-node positive breast cancer women treated with adjuvant chemotherapy. Further analyses in larger cohorts are warranted to investigate possible differential effect of distinct PIK3CA mutations in small subgroups of patients.
BACKGROUND: Mutations in the tumor suppressor gene TP53 and proto-oncogene PIK3CA and alterations of p53 and PIK3CA AKT mTOR pathways are common events in several human cancers. We focused on the analysis of TP53 and PIK3CA
style='font-weight:700;'>PIK3CA gene variations in adenocarcinoma, squamous cell carcinoma as well as in intraepithelial neoplasia grade 3 of the cervix. METHODS: DNA samples from 28 cervical adenocarcinoma, 55 squamous cell carcinoma and 31 intraepithelial neoplasia grade 3 (CIN3), previously characterized in terms of human papillomavirus (HPV) prevalence and genotype distribution, were analyzed for TP53 and PIK3CA mutations in the exons 4-9 and exon 9, respectively. RESULTS: Single nucleotide substitutions in TP53 and PIK3CA genes were detected in 36% and 11% of adenocarcinoma, in 16% and in 5% of squamous cell carcinoma, and in 13% and none of CIN 3, respectively. Nucleotide changes in TP53 were significantly more frequent in adenocarcinoma cases than in squamous cell carcinoma and CIN3 (P = 0.035) and were independent from HPV infection status. CONCLUSIONS: Mutations in the TP53 gene and to lesser extent in the PIK3CA gene seem more frequent in cervical adenocarcinoma than in squamous cell carcinoma and CIN3. Whether TP53 and PIK3CA gene mutations have an impact on prognosis and response to molecularly targeted therapies as well as in cytotoxic drugs in different cervical cancer histotypes needs to be analyzed in investigative clinical trials.
Ji Y, etal., Front Pharmacol. 2021 Apr 15;12:643456. doi: 10.3389/fphar.2021.643456. eCollection 2021.
Numerous studies have revealed that oxidative stress is closely associated with the occurrence and development of depression. Xiaoyao Pills (XYW) are included in the Chinese Pharmacopoeia and are frequently used for treating anxiety and depression by smoothing the liver, strengthening the spleen, an
d nourishing the blood. However, the antidepressant effects of XYW have not yet been thoroughly investigated. The objective of our study was to investigate the antidepressant-like effects of XYW and the underlying molecular mechanism in the olfactory bulbectomized (OB) rat model of depression using the open field test (OFT), sucrose preference test (SPT), splash test (ST), and novelty suppressed feeding test (NSFT). Results showed that XYW (0.93 and 1.86 g·kg-1) significantly alleviated depression-like behaviors in rats, which was indicated by increased sucrose preference in the SPT, prolonged grooming time in the ST, decreased horizontal movement in the OFT, and shorter feeding latency in the NSFT. In addition, XYW treatment dramatically reversed the reduced activity of superoxide dismutase and the decreased level of glutathione, while also lowering levels of malondialdehyde, an inflammatory mediator (nitric oxide), and pro-inflammatory cytokines (interleukin-6 and 1β) in the serum and cortex of OB rats. Mechanistically, XYW induced marked upregulation of mRNA and protein expression levels of NFE2L2, KEAP1, GPX3, HMOX1, SOD1, NQO1, OGG1, PIK3CA, p-AKT1/AKT1, NTRK2, and BDNF, and downregulation of ROS in the cortex and hippocampus via the activation of the NFE2L2/KEAP1, PIK3CA/AKT1, and NTRK2/BDNF pathways. These findings suggest that XYW exert antidepressant-like effects in OB rats with depression-like symptoms, and these effects are mediated by the alleviation of oxidative stress and the enhancement of neuroprotective effects through the activation of the PIK3CA-AKT1-NFE2L2/BDNF signaling pathways.
