The Role of FGFR3 in the Progression of Bladder Cancer.

Introduction: Bladder cancer is associated with a high recurrence rate, and outcomes for muscle-invasive and metastatic disease remain poor. New targeted therapies, such as the FGFR inhibitor erdafitinib, have been introduced, but the progression from non-muscle-invasive to muscle-invasive disease remains a major clinical challenge. Methods: In this study, we performed immunohistochemical staining for FGFR1-FGFR4 on surgical specimens from 192 cases of urothelial carcinoma. We also conducted various functional assays on human bladder cancer cell lines to assess protein/gene expression, cell proliferation, migration, invasion, and colony formation. Results: FGFR2 and FGFR3 expressions were found to be significantly down-regulated in high-grade (0.014) and muscle-invasive (0.002) tumors, respectively. Functionally, the FGFR inhibitor erdafitinib suppressed cell proliferation and migration, and FGFR3 silencing also markedly reduced proliferation, migration, invasion, and colony formation in cancer cell lines. Conclusions: The down-regulation of FGFR3 in muscle-invasive bladder cancer, coupled with the inhibitory effect of its inactivation on cell growth, suggests a significant role for FGFR3 in bladder cancer progression.