title: Activation of proteinase-activated receptor 1 promotes human colon cancer cell proliferation through epidermal growth factor receptor transactivation.
abstract: Serine proteases are now considered as crucial contributors to the development of human colon cancer. We have shown recently that thrombin is a potent growth factor for colon cancer cells through activation of the aberrantly expressed protease-activated receptor 1 (PAR1). Here, we analyzed the signaling pathways downstream of PAR1 activation, which lead to colon cancer cell proliferation in HT-29 cells. Our data are consistent with the following cascade of events on activation of PAR1 by thrombin or specific activating peptide: (a) a matrix metalloproteinase-dependent release of transforming growth factor-alpha (TGF-alpha) as shown with TGF-alpha blocking antibodies and measurement of TGF-alpha in culture medium; (b) TGF-alpha-mediated activation of epidermal growth factor receptor (EGFR) and subsequent EGFR phosphorylation; and (c) activation of extracellular signal-regulated protein kinase 1/2 (ERK1/2) and subsequent cell proliferation. The links between these events are shown by the fact that stimulation of cell proliferation and ERK1/2 on activation of PAR1 is reversed by the MMP inhibitor batimastat, TGF-alpha neutralizing antibodies, EGFR ligand binding domain blocking antibodies, and the EGFR tyrosine kinase inhibitors AG1478 and PD168393. Therefore, transactivation of EGFR seems to be a major mechanism whereby activation of PAR1 results in colon cancer cell growth. Finally, PAR1 activation induces Src phosphorylation, which is reversed by using the Src tyrosine kinase inhibitor PP2, suggesting that Src activation plays a permissive role for PAR1-mediated ERK1/2 activation and cell proliferation probably acting downstream of the EGFR. These data explain how thrombin exerts robust trophic action on colon cancer cells and underline the critical role of EGFR transactivation.
authors.affiliation: Neuroendocrinologie et Biologie Cellulaire Digestives, Institut National de la Sante et de la Recherche Medicale U410, Faculté de Médecine Xavier Bichat, 75018 Paris, France. darmoul@bichat.inserm.fr
authors.forename: Dalila
authors.initials: D
authors.lastname: Darmoul
authors.forename: Valérie
authors.initials: V
authors.lastname: Gratio
authors.forename: Hélène
authors.initials: H
authors.lastname: Devaud
authors.forename: Franck
authors.initials: F
authors.lastname: Peiretti
authors.forename: Marc
authors.initials: M
authors.lastname: Laburthe
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000276:immunology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D044463:Receptor, PAR-1 / Q000819:agonists / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects*; D016211:Transforming Growth Factor alpha / Q000037:antagonists & inhibitors / Q000276:immunology / Q000494:pharmacology; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D061965:Matrix Metalloproteinase Inhibitors; D044463:Receptor, PAR-1; D016211:Transforming Growth Factor alpha; D066246:ErbB Receptors; D019061:src-Family Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D020782:Matrix Metalloproteinases