TRPV4 Orchestrates Distinct Calcium and Cell Growth Responses in Non-Tumorigenic and Clear Cell Renal Carcinoma-Derived Cells.

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of kidney cancer and often exhibits resistance to conventional therapies. Calcium signaling plays a critical role in cancer progression, and the non-selective cation channel TRPV4 (Transient Receptor Potential Vanilloid 4) has been implicated in tumorigenesis across multiple cancer types. However, its specific role in ccRCC remains poorly understood. In this study, we investigated TRPV4 subcellular localization and functional activity in ccRCC-derived cell lines (786-O and Caki-1) compared to non-tumorigenic renal epithelial cells (HK-2). Immunofluorescence analyses revealed stronger TRPV4 colocalization with Hoechst-stained nuclei in carcinoma-derived renal cells compared with non-tumorigenic controls. TRPV4 activation elicited a faster and more robust intracellular calcium increase in ccRCC cells. Quantification of cell number after 96 h revealed that TRPV4 inhibition reduced cell growth, whereas activation increased it, particularly in metastatic Caki-1 cells. In 3D cultures, Caki-1 cells formed spheroids whose size, morphology, and viability were significantly modulated by TRPV4 activity. TRPV4 inhibition produced smaller, more compact spheroids with reduced viability, while activation promoted the formation of larger structures. Notably, TRPV4 inhibition induced its exclusion from the nucleus and redistribution to the cytoplasm, where it colocalized with aquaporin-1 (AQP1), a water channel associated with favorable prognosis in ccRCC. These findings suggest that TRPV4 contributes to ccRCC progression by modulating calcium dynamics, subcellular organization, and tumor cell behavior. Taken together, our findings position TRPV4 as a functionally relevant ion channel in ccRCC, supporting its further exploration as a therapeutic target in renal cancer.