Trypsin stimulates integrin alpha(5)beta(1)-dependent adhesion to fibronectin and proliferation of human gastric carcinoma cells through activation of proteinase-activated receptor-2

Trypsin is widely expressed in various non-pancreatic tissues at low levels and overexpressed in some types of human cancers. In the present study, we found that trypsin stimulates integrin-dependent adhesion and growth of MK N-1 human gastric carcinoma cells. MKN-1 cells expressed both proteinase-ac tivated receptor-1 (PAR-1) and PAR-2, which are activated by thrombin and t rypsin, respectively. Both trypsin and the PAR-S ligand SLIGKV promoted int egrin alpha(5)beta(1)-mediated adhesion of MKN-1 cells to fibronectin, and less effectively integrin alpha(v)beta(3)-mediated cell adhesion to vitrone ctin, but not that to type IV collagen or laminin-l at all. Thrombin and th e PAR-1 ligand SFLLRN promoted the cell adhesion to vitronectin more strong ly than trypsin or the PAR-2 ligand, but not the cell adhesion to fibronect in at all. The cell adhesion-stimulating effect of the PAR-S ligand was sig nificantly reduced by the pre-treatment of cells with trypsin, indicating t hat the effect of trypsin is mediated by PAR-S activation. The trypsin-stim ulated cell adhesion to vitronectin, but not to fibronectin, was effectivel y inhibited by the Gi protein blocker pertussis toxin, and both cell adhesi ons were completely inhibited by the Src kinase inhibitor herbimycin A. Fur thermore, trypsin and the PAR-2 ligand stimulated growth of MKN-1 cells mor e strongly than thrombin or the PAR-1 ligand. These results show that tryps in regulates cellular adhesion and proliferation by inducing PAR-BIG protei n signalings, and that the integrin alpha(5)beta(1)- and integrin alpha(v)b eta(3)-dependent cell adhesions are regulated by different PAR/G protein si gnalings.Trypsin is widely expressed in various non-pancreatic tissues at l ow levels and overexpressed in some types of human cancers. In the present study, we found that trypsin stimulates integrin-dependent adhesion and gro wth of MKN-1 human gastric carcinoma cells. MKN-1 cells expressed both prot einase-activated receptor-1 (PAR-1) and PAR-2, which are activated by throm bin and trypsin, respectively. Both trypsin and the PAR-S ligand SLIGKV pro moted integrin alpha(5)beta(1)-mediated adhesion of MXN-1 cells to fibronec tin, and less effectively integrin alpha(v)beta(3)-mediated cell adhesion t o vitronectin, but not that to type IV collagen or laminin-1 at all. Thromb in and the PAR-1 ligand SFLLRN promoted the cell adhesion to vitronectin mo re strongly than trypsin or the PAR-2 ligand, but not the cell adhesion to fibronectin at all. The cell adhesion-stimulating effect of the PAR-S ligan d was significantly reduced by the pre-treatment of cells with trypsin, ind icating that the effect of trypsin is mediated by PAR-S activation. The try psin-stimulated cell adhesion to vitronectin, but not to fibronectin, was e ffectively inhibited by the Gi protein blocker pertussis toxin, and both ce ll adhesions were completely inhibited by the Src kinase inhibitor herbimyc in A. Furthermore, trypsin and the PAR-2 ligand stimulated growth of MKN-1 cells more strongly than thrombin or the PAR-1 ligand. These results show t hat trypsin regulates cellular adhesion and proliferation by inducing PAR-B IG protein signalings, and that the integrin alpha(5)beta(1)- and integrin alpha(v)beta(3)-dependent cell adhesions are regulated by different PAR/G p rotein signalings.