Bombesin and gastrin releasing peptide increase tyrosine phosphorylation of focal adhesion kinase and paxillin in non-small cell lung cancer cells

Abstract

The effects of some oncogenes, growth factors and neuropeptides are mediated by tyrosine phosphorylation of focal adhesion kinase (p125 FAK) and paxillin cytoskeletal proteins. In this study the ability of bombesin/gastrin releasing peptide (BB/GRP) to stimulate tyrosine phosphorylation of p125 FAK and paxillin in non-small cell lung cancer (NSCLC) H1299 cells was investigated. BB, 100 nM caused increased p125 FAK and paxillin tyrosine phosphorylation maximally after 1 min. The effect of BB on p125 FAK and paxillin tyrosine phosphorylation was concentration-dependent being half maximal at 4–8 nM. Also, 100 nM GRP, GRP 14–27 but not GRP 1–16 increased p125 FAK and paxillin tyrosine phosphorylation indicating that the C-terminal of GRP is essential. BW2258U89, a GRP receptor antagonist, caused a dose-dependent inhibition of BB-stimulated p125 FAK and paxillin tyrosine phosphorylation with an IC 50 value of 3 μM. Cytochalasin D (0.3 μM), which inhibits actin polymerization, reduced the ability of BB to stimulate tyrosine phosphorylation of p125 FAK and paxillin. Genistein (50 μM) and H-7 (50 μM), which are kinase inhibitors, reduced the tyrosine phosphorylation of p125 FAK and paxillin stimulated by BB. Also, treatment of NCI-H1299 cells with FAK antisense resulted in decreased FAK tyrosine kinase activity and proliferation. These results suggest that p125 FAK is an important enzyme for NSCLC proliferation.