Cx43 modulates malignant phenotypes in bladder cancer cells via the c-Src/PTEN/FAK axis

Bladder cancer (BC), a leading urogenital malignancy with high mortality, lacks effective early biomarkers. Connexin 43 (Cx43), encoded by GJA1, regulates tumor growth via protein interactions and phosphorylation. While dysregulated in BC, Cx43's downstream regulatory pathways remain unclear. Elucidating these mechanisms is crucial for identifying novel biomarkers and therapeutic targets. qRT-PCR measured Cx43 expression in bladder cancer tissues and cells. Kaplan-Meier analysis assessed correlation between Cx43 expression and patient overall survival (OS) and progression-free survival (PFS). Using MTT, colony formation, and Transwell assays, we evaluated how silencing Cx43 affects BC cell proliferation, migration, and invasion in vitro. Protein-protein interaction (PPI) analysis predicted potential Cx43 downstream targets. Co-immunoprecipitation (Co-IP) confirmed specific interaction between Cx43 and c-Src proteins. Western blotting (WB) examined effects of Cx43 knockdown on expression of these predicted downstream targets. Finally, in vivo mouse xenografts validated Cx43's role in BC cell tumorigenesis. Cx43 was upregulated in bladder cancer tissues and its elevated expression correlated with poor patient prognosis. Silencing Cx43 significantly suppressed BC cell proliferation, migration, and invasion. Functional rescue experiments implicated the c-Src/PTEN pathway in mediating the oncogenic effects of Cx43. Mechanistically, Cx43 drives BC progression by facilitating c-Src-mediated suppression of the tumor suppressor PTEN and subsequent activation of FAK signaling. This study unveiled a novel regulatory pathway, Cx43 promotes malignant bladder cancer progression by modulating the c-Src/PTEN/p-FAK axis.