Role of complex cadherins in cell-cell adhesion evaluated by spheroid formation in renal cell carcinoma cell lines

We have previously shown that renal cell carcinoma (RCC) cell lines expressed a complex set of cadherins, e.g. E-cadherin, N-cadherin and cadherin-6. It is also reported that E-cadherin and cadherin-6 have a predictive value for estimating a patient's prognosis in RCC. However, E-cadherin is infrequently expressed in RCC as compared with N-cadherin and cadherin-6. In the present study, therefore, we performed a functional analysis of these cadherins as a cell adhesion molecule using spheroid culturing and spheroid-blocking assay. In E-cadherin expressers, compact spheroid formation was observed, and it was inhibited by anti-E-cadherin antibody. In contrast, in E-cadherin-absent lines, cadherin-6 apparently played a role to form relatively loose spheroids and this spheroid formation was inhibited by anti-cadherin-6 antibody. In both spheroids, the anti-N-cadherin antibody could not inhibit their formation, suggesting that N-cadherin was not an essential molecule for spheroid formation in the cell lines expressing complex cadherins. The anti-N-cadherin antibody inhibited spheroid formation only in the cell line that expressed N-cadherin alone. Using western blot analysis, immunohistochemistry and immunoprecipitation, these cadherins were linked to catenins to make a functional adhesion molecule. In conclusion, E-cadherin and cadherin-6 are shown to act in cell-cell adhesion whereas N-cadherin might play a somewhat different role from cell-cell adhesion in RCC cell lines.