부산대학교 도서관

Substance P (SP) analogues including [d-Arg1,d-Trp5,7,9,Leu11]SP are broad spectrum neuropeptide antagonists and potential anticancer agents, but their mechanism of action is not fully understood. Here, we examined the mechanism of action of [d-Arg1,d-Trp5,7,9,Leu11]SP as an inhibitor of G protein-coupled receptor (GPCR)-mediated signal transduction and cellular DNA synthesis in Swiss 3T3 cells. Addition of [d-Arg1,d-Trp5,7,9,Leu11]SP, at 10 μm, caused a striking rightward shift in the dose-response curves of DNA synthesis induced by bombesin, bradykinin, or vasopressin and markedly inhibited the activation of p42mapk (ERK-2) and p44mapk (ERK-1) induced by these GPCR agonists. In addition, this SP analogue also prevented the protein kinase C-dependent activation of protein kinase D induced by these agonists. [d-Arg1,d-Trp5,7,9,Leu11]SP, at a concentration (10 μm) that inhibited these Gq-mediated events, also prevented GPCR agonist-induced responses mediated through the G proteins of the G12subfamily. These include bombesin-induced assembly of focal adhesions, formation of parallel arrays of actin stress fibers, increase in the tyrosine phosphorylation of focal adhesion kinase (FAK), p130Cas, and paxillin, and formation of a complex between FAK and Src. We conclude that [d-Arg1,d-Trp5,7,9,Leu11]SP acts as a mitogenic antagonist of neuropeptide GPCRs blocking signal transduction via both Gq and G12.