Expression of claudins in human clear cell renal cell carcinoma

The current study investigated the expression of claudins 1, 5 and 16 in human clear cell renal cell carcinoma (CCRCC) and the impact of claudin-16 on kidney cancer cells. Levels of claudin transcripts were assessed using quantitative reverse transcription-polymerase reaction and proteins were examined by immunohistochemical methods. Human kidney epithelial cell HEK293 and human kidney cancer cell line UMRC2 were also used in the study. Human kidney tissues expressed high levels of claudin-1 and in particular claudin-16, but were negative for claudin-5. Late-stage kidney carcinomas tended to express low levels of claudin-1 and claudin-16. UMRC2 cells, highly positive for claudin-16, were transfected with an anti-claudin-16 transgene, which resulted in significant reduction in both transepithelial resistance and cell matrix adhesion compared to control cells. When HEK293 cells, negative for expression of claudin-16, were forced to express claudin-16, the cells showed a marked increase in transepithelial resistance and to some degree in cell matrix adhesion. In conclusion, the present study showed that kidney tissue and CCRCC tissues highly expressed claudin-16 and claudin-1, and that claudin-16 has a profound impact on barrier function and cell adhesion in kidney cancer cells.