Background
Cisplatin-based cytotoxic chemotherapy is considered to be the first-line therapy for advanced bladder cancer (BC), but resistance to cisplatin limits its antitumor effect. Fibroblast growth factor receptor 3 (FGFR3) has been reported to contribute to the progression and cisplatin resistance of BC. Meanwhile, chromobox protein homologue 7 (CBX7) was reported to inhibit BC progression. And our previous RNA-seq data on CBX7 (GSE185630) suggested that CBX7 might repress FGFR3, but the underlying mechanism and other cancer-related functions of CBX7 are still unknown.
Conclusions
These results suggest that CBX7 is an ideal candidate to overcome cisplatin resistance in BC.
Methods
Silico analysis of RNA-seq data to identify the upstream regulators and downstream target genes of CBX7. The western blot analysis, quantitative real-time PCR (RT-qPCR), chromatin immunoprecipitation (ChIP)-qPCR analysis, CCK-8 assay, and nude mice xenograft models were used to confirm the enhancer of zeste homologue (EZH2)/CBX7/ FGFR3 axis.
Results
In this study, we first showed that CBX7 is downregulated in BC. Then, we revealed that EZH2 represses CBX7 expression by increasing H3K27me3 in BC cells. Moreover, we demonstrated that CBX7 directly downregulates FGFR3 expression and sensitises BC cells to cisplatin treatment by inactivating the phosphatidylinositol 3-kinase (PI3K)-(RAC-alpha serine/threonine-protein kinase) AKT signalling pathway. Conclusions: These results suggest that CBX7 is an ideal candidate to overcome cisplatin resistance in BC.