Inhibition of focal adhesion kinase expression or activity disrupts epidermal growth factor-stimulated signaling promoting the migration of invasive human carcinoma cells

Elevated focal adhesion kinase (FAK) expression in human tumor cells has be en correlated with an increased cell invasion potential. In cell culture, s tudies with FAK-null fibroblasts have shown that FAK function is required f or cell migration. To determine the role of elevated FAK expression in faci litating epidermal growth factor (EGF)-stimulated human adenocarcinoma (A54 9) cell motility, antisense oligonucleotides were used to reduce FAK protei n expression >75%. Treatment of A549 cells with FAK antisense (ISIS 15421) but not a mismatched control (ISIS 17636) oligonucleotide resulted in reduc ed EGF-stimulated p130(Cas)-Src complex formation, e-Jun NH2-terminal kinas e (JNK) activation, directed cell motility, and serum-stimulated cell invas ion through Matrigel. Because residual FAK protein in ISIS 15421-treated A5 49 cells was highly phosphorylated at the Tyr-397/Src homology (SH)2 bindin g site, expression of the FAK COOH-terminal domain (FRNK) was also used as an inhibitor of FAK function. Adenoviral-mediated infection and expression of FRNK promoted FAK dephosphorylation at Tyr-397, resulted in reduced EGF- stimulated JNK as well as extracellular-regulated kinase 2 (ERK2) kinase ac tivation, inhibited matrix metalloproteinase-9 (MMP-9) secretion, and poten tly blocked both random and EGF-stimulated A549 cell motility. Equivalent e xpression of a FRNK (S-1034) point-mutant that did not promote FAK dephosph orylation also did not affect EGF-stimulated signaling or cell motility. Do se-dependent reduction in EGF-stimulated A549 motility was observed with th e PD98059 MEK1 inhibitor and the batimastat (BB-94) inhibitor of MMP activi ty, but not with the SB203580 inhibitor of P38 kinase. Finally, comparisons between normal, FAK-null, and FAK-reconstituted fibroblasts revealed that FAK enhanced EGF-stimulated JNK and ERK2 kinase activation that was require d for cell motility. These data indicate that FAK functions as an important signaling platform to coordinate EGF-stimulated cell migration in human tu mor cells and support a role for inhibitors of FAK expression or activity i n the control of neoplastic cell invasion.