Differential regulation of cell motility and invasion by FAK

Abstract

Cell migration and invasion are fundamental components of tumor cell metastasis. Increased focal adhesion kinase (FAK) expression and tyrosine phosphorylation are connected with elevated tumorigenesis. Null mutation of FAK results in embryonic lethality, and FAK−/− fibroblasts exhibit cell migration defects in culture. Here we show that viral Src (v-Src) transformation of FAK−/− cells promotes integrin-stimulated motility equal to stable FAK reexpression. However, FAK−/− v-Src cells were not invasive, and FAK reexpression, Tyr-397 phosphorylation, and FAK kinase activity were required for the generation of an invasive cell phenotype. Cell invasion was linked to transient FAK accumulation at lamellipodia, formation of a FAK–Src-p130Cas–Dock180 signaling complex, elevated Rac and c-Jun NH2-terminal kinase activation, and increased matrix metalloproteinase expression and activity. Our studies support a dual role for FAK in promoting cell motility and invasion through the activation of distinct signaling pathways.

Intrinsic focal adhesion kinase activity controls orthotopic breast carcinoma metastasis via the regulation of urokinase plasminogen activator expression in a syngeneic tumor model

“…As treatment of control 4T1 cells with inhibitors to Src-family PTKs, JNK and MEK1-ERK blocked uPA expression, and previous studies have shown that FAK can promote Src, JNK and ERK activation , it is possible that a multi-protein signaling complex with FAK generates signals to ERK and JNK leading to changes in uPA expression. This conclusion is supported by the fact that v-Src-stimulated cell invasion is linked to the formation of a FAK-Src-p130Cas-Dock180 signaling complex, elevated Rac and JNK activation and increased MMP expression and activity (Hsia et al, 2003). Further, inhibition of Src and MAPK activation blocks an ErbB2/3 to FAK signaling linkage, promoting cell invasion (Benlimame et al, 2005).…”

“…As FAK facilitates invadopodia formation by v-Src (Hauck et al, 2001;Hsia et al, 2003), we investigated the localization and activity of FAK within murine 4T1 breast carcinoma cells (Figure 1). 4T1 cells are highly invasive and spontaneously metastasize upon orthotopic implantation in BALB/c mice (Aslakson and Miller, 1992).…”

“…In vitro kinase assay For FAK, kinase assays were initiated by adding [g-32 P]ATP to immunoprecipitates and incubated at 321C for 15 min as described (Hsia et al, 2003). Following SDS-PAGE, the gels were dried and radiolabel incorporation into FAK was quantified using a phosphorimager (Imagequant; GE Healthcare Life Sciences, Piscataway, NJ, USA).…”

“…Whereas high levels of FRNK can promote cell apoptosis (Xu et al, 2000;Golubovskaya et al, 2002), FRNK expression can also reduce tumor growth by promoting tumor dormancy and by inhibiting cell proliferation (Aguirre Ghiso, 2002;van Nimwegen et al, 2005). Low levels of FRNK expression have revealed the importance of FAK activity in promoting tumor cell migration (Slack et al, 2001) and in generating an invasive cell phenotype (Hauck et al, 2001(Hauck et al, , 2002bHsia et al, 2003;.…”

“…As strategies using antisense oligonucleotides (Xu et al, 1996;Hauck et al, 2001) or RNA interference (RNAi) (Duxbury et al, 2003;Han et al, 2004) can reduce FAK expression in tumor cells, these methods have not yet been tested for specificity via FAK reconstitution and rescue assays. Only in RNAi-treated normal fibroblasts (Tilghman et al, 2005) and in reconstituted FAK-null (Owen et al, 1999;Sieg et al, 1999) or v-Src-transformed FAK-null fibroblasts (Hsia et al, 2003;Wu et al, 2005) have FAK re-expression and tyrosine phosphorylation been linked to the promotion of cell motility and/or invasion.…”