βig-h3 Interacts with α3β1 Integrin to Promote Adhesion and Migration of Human Hepatoma Cells

Abstract

βig-h3 is a TGF-induced extracellular matrix (ECM) protein. Our previous evidence suggests that β ig-h3 may promote adhesion and invasion potential of human hepatoma cells, but the mechanism underlying this process is still unknown. The present study identifies a pivotal role for molecules of the β ig-h3 signal transduction pathway. We demonstrated that β ig-h3 co-immunoprecipitated with α 3β 1 integrin in human 7721 hepatoma cells. The addition of α 3β 1 integrin antibodies inhibited the elevated adhesion and migration in β ig-h3-over-expressing 7721 cells, but not in β ig-h3 siRNA transfected 7721 cells. The expression and activity of integrin downstream molecules FAK and paxillin show a positive correlation with β ig-h3 expression in different human hepatoma cells. Levels of focal adhesions and stress fibers were decreased in β ig-h3 siRNA transfected 7721 cells. We suggest that by interaction with α 3β 1 integrin, β ig-h3 activates FAK-paxillin signaling linkage, leads to cytoskeleton reorganization, and thus enhances the metastatic potentials of human hepatoma cells.