PAR1-type thrombin receptor stimulates migration and matrix adhesion of human colon carcinoma cells by a PKCepsilon-dependent mechanism.

The proteinase-activated receptor1 (PAR1) was characterized as a functional receptor for thrombin in cells from different tumor entities. In colon carcinoma, its function has to be defined. In this study we demonstrate that the PAR1-selective agonist peptide TFLLRN induced activation of protein kinase C isoenzymes alpha and epsilon in human HT-29 colon carcinoma cells expressing PAR1 endogeneously. On the cellular level, TFLLRN and thrombin prompted HT-29 cell migration and matrix adhesion by a PKCepsilon-dependent mechanism as concluded because of the inhibition of PAR1-mediated effects by the PKC inhibitor bisindolylmaleimide I and the PKCepsilon translocation inhibitory peptide EAVSLKPT but not by the PKC inhibitor Gö 6976. In addition, blockade of PAR1 by RWJ 56110, a selective PAR1 antagonist, fully abolished the effect of thrombin on HT-29 cell migration and adhesion. Therefore, PAR1 seems to be the responsible receptor for thrombin-induced migration and adhesion of human colon carcinoma cells including PKCepsilon as an essential signal transducer.