Integrin expression on cell adhesion function and up-regulation of P125FAK and paxillin in metastatic renal carcinoma cells.

Integrins from normal human renal cortex epithelial cells (RCEC) and from four renal carcinoma lines (metastatic Caki-1, non-metastatic Caki-2, metastatic ACHN, and non-metastatic 769-P) were compared by immunoprecipitation with specific anti-integrin antibodies. Integrin alpha 2 was present in normal RCEC, but absent in all four tumor lines. There was a 2.0-3.0 fold decrease of alpha 3 and beta 1 in localized tumor lines, and a further 5.0-7.0 fold decrease in metastatic lines over their expression in normal renal cells. No alpha V was detected in Caki-1 cells. The greatest adhesion of all cells occurred in the presence of a stimulatory anti-alpha 3 antibody, mediated by specific matrix proteins employed as substrates, while anti-beta 1 treatment dramatically inhibited cell attachment on collagen IV, plasma fibronectin, laminin and merosin substrates. In addition, the mRNA expression of focal adhesion kinase (p125FAK) and paxillin were up-regulated (2.0-2.5 fold increase) in the metastatic Caki-1 cells over normal RCEC. The alteration of integrin subunits alpha 2, alpha 3, alpha V, beta 1, as well as p125FAK and paxillin may contribute to the pathogenicity and/or metastatic propensity of renal epithelial tumors. The up-regulation of paxillin independently or in concert with p125FAK as shown in this study indicates its significant role as a potential marker of metastasis in renal carcinoma cells.