title: MAP kinase-mediated proliferation of DLD-1 carcinoma by the stimulation of protease-activated receptor 2.
abstract: Protease-activated receptor-2 (PAR-2) has been demonstrated to be highly expressed in the gastrointestinal tract. In the present study, we investigated the effects of PAR-2 stimulation on the cell signaling and proliferation of DLD-1, a human colon carcinoma cell line, in comparison with the PAR-1 stimulation. PAR-2 stimulation by agonist peptide SLIGKV concentration-dependently induced the increase in [Ca2+]i and the proliferation of DLD-1 whereas the inverse peptide LSIGKV did not. Trypin (10(-9) M), an agonist protease for PAR-2, also enhanced the proliferation of DLD-1. The proliferative response of DLD-1 to PAR-2 stimulation was associated with the transient phosphorylation of MEK and MAP kinase, but not p38 MAP kinase and JNK. Inhibition of MEK by PD98059 (50 microM) completely inhibited the proliferation-stimulating effects as well as the phosphorylation of MAP kinase induced by PAR-2 agonist peptide (100 microM) and trypsin (10(-9) M). The prolonged treatment with PAR-2 agonist peptide for more than one hour was required for the enhanced proliferative response, suggesting the existence of unknown long-lasting cooperative signaling with MAP kinase cascade. PAR-1 stimulation by the agonist peptide SFLLRN (100 microM) or thrombin (10(-8) M) produced Ca2+ signaling, however, the stimulation neither produced the cell proliferative response nor the activation of MEK-MAP kinase cascade. These results indicated that Ca2+ signaling induced by PARs activation was not enough for inducing the cell proliferation in DLD-1 cells and that stimulation of PAR-2 can induce the activation of MEK-MAP kinase cascade, leading to the growth promoting response.
mesh_terms: D002118:Calcium / Q000378:metabolism; D002277:Carcinoma / Q000473:pathology*; D002455:Cell Division; D003110:Colonic Neoplasms / Q000473:pathology*; D003600:Cytosol / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D007202:Indicators and Reagents; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D044463:Receptor, PAR-1; D044464:Receptor, PAR-2; D018179:Receptors, Thrombin / Q000187:drug effects* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
chemical_list: D005419:Flavonoids; D007202:Indicators and Reagents; D044463:Receptor, PAR-1; D044464:Receptor, PAR-2; D018179:Receptors, Thrombin; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D002118:Calcium