HGF upregulates and modifies subcellular distribution of proteins in colon cancer cell enterocytic differentiation

Hepatocyte growth factor (HGF) and its receptor, c-Met, are involved in cell transformation. To study their role in intestinal cell differentiation, we used Caco-2 colon cancer cells, which differentiate spontaneously into enterocytes during culture. Cells grown continuously in the presence of HGF reached confluence more quickly than control cells. Markers of enterocytic differentiation, such as alkaline phosphatase and sucrase-isomaltase activities, adhesion molecules, and structural proteins such as E-cadherin, villin, and F-actin were upregulated by HGF throughout the 35 days of culture, and actin fibers were reorganized. HGF also stimulated expression and tyrosine phosphorylation of c-Met and Gab-1 as well as protein kinase C (PKC)-alpha expression. PKC-alpha has been shown to be involved in intestinal differentiation. We therefore investigated the possibility that increases in PKC-alpha protein levels were responsible for the HGF-promoted events. We did this by incubating cells with Gö-6976, an inhibitor of PKC-alpha and -beta1, concomitantly with HGF. This inhibitor abolished the HGF-induced increase in villin levels before, but not after, confluence. Thus HGF accelerates Caco-2 cell differentiation and stimulates the metabolic and structural events accompanying this process. These HGF-promoted events may be mediated partly by Gab-1, and the effects of HGF on villin before confluence seem to involve PKC.