Fn14 overcomes cisplatin resistance of high-grade serous ovarian cancer by promoting Mdm2-mediated p53-R248Q ubiquitination and degradation

BackgroundHigh-grade serous ovarian cancer (HGSOC) is the most lethal of all gynecological malignancies. Patients often suffer from chemoresistance. Several studies have reported that Fn14 could regulate migration, invasion, and angiogenesis in cancer cells. However, its functional role in chemoresistance of HGSOC is still unknown.MethodsThe expression of Fn14 in tissue specimens was detected by IHC. CCK-8 assay was performed to determine changes in cell viability. Apoptosis was measured by flow cytometry. The potential molecular mechanism of Fn14-regulated cisplatin resistance in HGSOC was investigated using qRT-PCR, western blotting, and Co-IP assays. The role of Fn14 in HGSOC was also investigated in a xenograft mouse model.ResultsIn this study, we found that Fn14 was significantly downregulated in patients with cisplatin resistance. Patients with low Fn14 expression were associated with shorter progression-free survival and overall survival. Overexpression of Fn14 suppressed cisplatin resistance in OVCAR-3 cells, whereas knockdown of Fn14 did not affect cisplatin resistance in SKOV-3 cells. Interestingly, Fn14 could exert anti-chemoresistance effect only in OVCAR-3 cells harboring a p53-R248Q mutation, but not in SKOV-3 cells with a p53-null mutation. We isolated and identified primary cells from two patients with the p53-R248Q mutation from HGSOC patients and the anti-chemoresistance effect of Fn14 was observed in both primary cells. Mechanistic studies demonstrated that overexpression of Fn14 could reduce the formation of a Mdm2-p53-R248Q-Hsp90 complex by downregulating Hsp90 expression, indicating that degradation of p53-R248Q was accelerated via Mdm2-mediated ubiquitin-proteasomal pathway.ConclusionOur findings demonstrate for the first time that Fn14 overcomes cisplatin resistance through modulation of the degradation of p53-R248Q and restoration of Fn14 expression might be a novel strategy for the treatment of HGSOC.