Vitamin D receptor suppresses proliferation and metastasis in renal cell carcinoma cell lines via regulating the expression of the epithelial Ca2+ channel TRPV5

We previously demonstrated that transient receptor potential vanilloid subfamily 5 (TRPV5) expression was decreased in renal cell carcinoma (RCC) compared with that in normal kidney tissues, a finding that was correlated with vitamin D receptor (VDR) expression, but further investigations is warranted. The aim of this study was to elucidate whether VDR could regulate the expression of TRPV5 and affect proliferation and metastasis in RCC. In this study, we used lentivirus to conduct the model of VDR overexpression and knockdown caki-1 and 786-O RCC cell lines in vitro. The results demonstrated that VDR overexpression significantly inhibited RCC cells proliferation, migration and invasion, and promoted apoptosis by the MTT, transwell cell migration/invasion and flow cytometry assays, respectively. However, VDR knockdown in RCC cells had the opposite effect. The RNA-sequence assay, which was assessed in caki-1 cells after VDR overexpression and knockdown, also indicated that significantly differentially expressed genes were associated with cell apoptotic, differentiation, proliferation and migration. RT-PCR and western blot analysis showed that VDR knockdown increased TRPV5 expression and VDR overexpression decreased TRPV5 expression in caki-1 cells. Furthermore, knockdown of TRPV5 expression suppressed the VDR knockdown-induced change in the proliferation, migration and invasion in caki-1 cells. Taken together, these findings confirmed that VDR functions as a tumour suppressor in RCC cells and suppresses the proliferation, migration and invasion of RCC through regulating the expression of TRPV5.