Beta 1-integrin expression and function in human bladder cancer cells: modulation by TNF-alpha.

Cytofluorimetric and biochemical analysis ill two different grade human bladder cancer cell lines showed that G3 EJ cells exhibited higher levels of alpha 5 beta 1 and alpha 6 beta 1 heterodimers, and the G2 RT112 cell line higher levels of alpha 2 beta 1. Alpha6/beta4 receptor was detected only in RT112 cells. Adhesion assays with extracellular matrix proteins indicated that both cells bound to fibronectin, laminin and collagen I, the adhesive properties bring related to the integrin profile. Inhibition tests revealed that alpha 5 beta 1 mediated adhesion to fibronectin, alpha 3 beta 1 and alpha 6 beta 1 to laminin, and that alpha 2 beta 1 was the main mediator of adhesion to collagen I in both cell lines. In EJ but not in RT112 cells, tumor necrosis factor-alpha induced the upregulation of alpha 2, which mediated increased adhesion to collagen I. The different effects of TNF alpha on the two cell lines were not attributable to differences in tumor necrosis factor responsiveness, as both cells expressed comparable levels of tumor necrosis factor receptor-1 and the tumor necrosis factor-inducible intercellular adhesion molecule-1.