Src protein kinase pp60c-src influences adhesion stabilization of HT-29 colon carcinoma cells to extracellular matrix components under dynamic conditions of laminar flow.

Tumor cell adhesion to extracellular matrix (ECM) and its stabilization are important determinants in metastasis formation, and they are mediated, in part, by integrins and regulated by a variety of protein kinases. Protein tyrosine kinase pp60c-src is found in adhesion-dependent focal adhesion plaques where it may regulate different integrin-mediated signaling cascades. Using human HT-29 colon carcinoma cells stably transfected with pp60c-src--specific antisense oligonucleotides (HT-29AS15), we investigated the role of pp60c-src in integrin-mediated adhesion and its stabilization to ECM components collagen I or IV under static and laminar fluid flow conditions. Under static adhesion conditions transfection of pp60c-src antisense oligonucleotides did not modify adhesive properties. Phosphorylation of focal adhesion kinase (FAK) and paxillin induced by static adhesion to collagen I or IV were similar in HT-29P and HT-29AS15 cells. However, using hydrodynamic conditions in a laminar flow chamber we found a slight reduction in early adhesion events and an even greater difference in adhesion stabilization rates (ASRs). The transfected cells showed a significant reduction in their ability to withstand shear forces and stabilize adhesive bounds. These changes correlated with the cellular expression levels of pp60c-src. Our results suggest that pp60c-src may be involved in stabilization of dynamic HT-29 cell adhesion to ECM components, and this kinase appears to be part of a mechanosensory protein complex during integrin-mediated cell adhesion.