Lu LY and Yu X, Cell Cycle. 2015;14(21):3454-60. doi: 10.1080/15384101.2015.1093701.
DNA damage response is required for male fertility. DNA damage repair mediates recombination between homologous chromosomes in meiotic prophase, which is essential for proper chromosome segregation during meiotic division. Interestingly, some DNA damage response proteins are also required for the su
rvival of premeiotic germ cells, but their roles in these cells are still unclear. CHFR was recently shown to participate in DNA damage response, but it remains to be established if CHFR is required for male fertility. In this study, we characterized Chfr knockout male mice and found that around 30% of them were infertile. The onset of spermatogenesis was delayed and there was significant increase in apoptosis in premeiotic germ cells. This resulted in complete loss of germ cells in testes in 3 months and azoospermia in these mice. We further demonstrated that ATM activation was compromised in the testes of these mice. Therefore, CHFR is important for the survival of male premeiotic germ cells, which is likely through maintaining genomic stability in spermatogonial stem cells.
The CpG island of the promoter region of the checkpoint with fork-head associated and ring finger gene (CHFR), a mitotic checkpoint gene with tumor-suppressor functions, is hypermethylated in various human cancers. The objective of this study was to evaluate the
frequency of aberrant CHFR promoter methylation in acute myeloid leukemia (AML) patients in an attempt to improve prognostication. CHFR promoter methylation levels were analyzed in 358 newly diagnosed AML cases and 30 healthy donors by the use of quantitative methylation-specific polymerase chain reaction. In addition, we analyzed possible association between CHFR hypermethylation and hematological characteristics, chromosome abnormalities, genetic mutations, and survival. Hypermethylation of the CHFR promoter was observed in 24% (85 of 358) AML patients, but not in healthy individuals. CHFR hypermethylation correlated significantly with SRSF2 and DNMT3A mutations. Patients with hypermethylation exhibited lower overall survival and shorter relapse-free survival than nonmethylated cases. In multivariate analysis, CHFR hypermethylation was an independent factor predicting poor overall survival but not relapse-free survival. In conclusion, hypermethylation of the CHFR promoter, frequent in AML, is associated with adverse outcome, and can thus be used for risk stratification.
Brodie SA, etal., Oncotarget. 2015 Oct 13;6(31):30773-86. doi: 10.18632/oncotarget.5040.
The mitotic checkpoint protein CHFR has emerged as a major mediator of taxane resistance in cancer. Here we show that CHFR's PAR-binding zinc finger domain (PBZ) mediates a protein interaction with poly-ADP ribosylated PARP1
leading to stabilization of CHFR. Disruption of the CHFR-PARP1 interaction through either PARP1 shRNA-mediated knockdown or overexpression of a PBZ domain peptide induces loss of CHFR protein expression. In an attempt to exploit this observation therapeutically, and to develop compounds with synthetic lethality in combination with taxanes, we performed a high-throughput computational screen of 5,256,508 chemical structures against the published crystal structure of the CHFR PBZ domain to identify candidate small molecule CHFR protein-protein interaction inhibitors. The 10 compounds with the best docking scores (< -9.7) were used for further in vitro testing. One lead compound in particular, termed 'A3', completely disrupted the protein-protein interaction between CHFR and PARP1, resulting in the inhibition of mitotic checkpoint function, and led to therapeutic synergy with docetaxel in cell viability and colony formation assays. In mouse xenografts, i.p. administration of 'A3' led to a significant reduction in nuclear CHFR protein expression with a maximal effect 4 hours after administration, confirming relevant pharmacodynamics following the peak of 'A3' plasma concentration in vivo. Furthermore, combination of A3 and taxane led to significant reduction of implanted tumor size without increase in hematological, hepatic or renal toxicity. These findings provide a proof-of-principle that small molecule inhibition of CHFR PBZ domain interaction is a novel potential therapeutic approach to increase the efficacy of taxane-based chemotherapy in cancer.
