Modulation of hepatocyte growth factor-induced scattering of HT29 colon carcinoma cells: Involvement of the MAPK pathway

Hepatocyte growth factor (HGF)/scatter factor modulates the motility of HT29 colon carcinoma cells in vitro by inducing morphological changes that depend on the type of extra-cellular matrix (ECM) ligand; HGF-induced scattering of HT29 cells is observed if cells are grown on plastic coated with serum proteins but not laminin. The absence of scattering correlates with a lack of cell spreading on laminin and it is not due to impaired HGF induced tyrosine phosphorylation of the E-cadherin/desmosome component, (gamma)-catenin, or lack of activation of mitogen activated protein kinase (MAPK). Treatment of HT29 cells with phorbol 12-myristate, 13-acetate (PMA), but not arachidonic acid, restored the ability of the cells to spread on laminin in an integrin-dependent manner. Moreover, the addition of both PMA and HGF restored the ability of these cells to scatter on laminin in a synergistic manner. This event correlated with increased tyrosine phosphorylation of paxillin and activation of MAPK. Moreover, when the MEK (MAPK kinase)/MAPK pathway was blocked by the MEK inhibitor PD098059, HGF-induced scattering of HT29 cells was blocked. Thus, HGF modulation of HT29 cell motility is regulated by both integrin and growth factor-dependent signaling and implicates MAPK in the modulation of intercellular adhesion and epithelial cell motility.