Fibroblast growth factor receptor type 4 as a potential therapeutic target in clear cell renal cell carcinoma

Background Several clear cell renal cell carcinoma (ccRCC) cases harbour fibroblast growth factor receptor 4 ( FGFR4 ) gene copy number (CN) gains. In this study, we investigated the functional contribution of FGFR4 CN amplification in ccRCC. Methods The correlation between FGFR4 CN determined via real-time PCR and protein expression evaluated using western blotting and immunohistochemistry was assessed in ccRCC cell lines (A498, A704, and 769-P), a papillary RCC cell line (ACHN), and clinical ccRCC specimens. The effect of FGFR4 inhibition on ccRCC cell proliferation and survival was assessed via either RNA interference or using the selective FGFR4 inhibitor BLU9931, followed by MTS assays, western blotting, and flow cytometry. To investigate whether FGFR4 is a potential therapeutic target, a xenograft mouse model was administered BLU9931. Results 60% of ccRCC surgical specimens harboured an FGFR4 CN amplification. FGFR4 CN was positively correlated with its protein expression. All ccRCC cell lines harboured FGFR4 CN amplifications, whereas ACHN did not. FGFR4 silencing or inhibition attenuated intracellular signal transduction pathways, resulting in apoptosis and suppressed proliferation in ccRCC cell lines. BLU9931 suppressed tumours at a tolerable dose in the mouse model. Conclusion FGFR4 contributes to ccRCC cell proliferation and survival following FGFR4 amplification, making it a potential therapeutic target for ccRCC.