Cyclin D1 in breast premalignancy and early breast cancer: implications for prevention and treatment

The effects of some oncogenes, growth factors and neuropeptides are mediated by tyrosine phosphorylation of focal adhesion kinase (p125FAK) and paxillin cytoskeletal proteins. In this study the ability of bombesin/gastrin releasing peptide (BB/GRP) to stimulate tyrosine phosphorylation of p125FAK and paxillin in non-small cell lung cancer (NSCLC) H1299 cells was investigated. BB, 100 nM caused increased p125FAK and paxillin tyrosine phosphorylation maximally after 1 min. The effect of BB on p125FAK and paxillin tyrosine phosphorylation was concentration-dependent being half maximal at 4–8 nM. Also, 100 nM GRP, GRP14–27 but not GRP1–16 increased p125FAK 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 p125FAK and paxillin tyrosine phosphorylation with an IC50 value of 3 μM. Cytochalasin D (0.3 μM), which inhibits actin polymerization, reduced the ability of BB to stimulate tyrosine phosphorylation of p125FAK and paxillin. Genistein (50 μM) and H-7 (50 μM), which are kinase inhibitors, reduced the tyrosine phosphorylation of p125FAK 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 p125FAK is an important enzyme for NSCLC proliferation.