An EGFR-Src-Arg-cortactin pathway mediates functional maturation of invadopodia and breast cancer cell invasion.

Invasive carcinoma cells use specialized actin polymerization-driven protrusions called invadopodia to degrade and possibly invade through the extracellular matrix (ECM) during metastasis. Phosphorylation of the invadopodium protein cortactin is a master switch that activates invadopodium maturation and function. Cortactin was originally identified as a hyperphosphorylated protein in v-Src-transformed cells, but the kinase or kinases that are directly responsible for cortactin phosphorylation in invadopodia remain unknown. In this study, we provide evidence that the Abl-related nonreceptor tyrosine kinase Arg mediates epidermal growth factor (EGF)-induced cortactin phosphorylation, triggering actin polymerization in invadopodia, ECM degradation, and matrix proteolysis-dependent tumor cell invasion. Both Src and Arg localize to invadopodia and are required for EGF-induced actin polymerization. Notably, Arg overexpression in Src knockdown cells can partially rescue actin polymerization in invadopodia while Src overexpression cannot compensate for loss of Arg, arguing that Src indirectly regulates invadopodium maturation through Arg activation. Our findings suggest a novel mechanism by which an EGFR-Src-Arg-cortactin pathway mediates functional maturation of invadopodia and breast cancer cell invasion. Furthermore, they identify Arg as a novel mediator of invadopodia function and a candidate therapeutic target to inhibit tumor invasion in vivo.

Mader CC ，Oser M ，Magalhaes MA ，Bravo-Cordero JJ ，Condeelis J ，Koleske AJ ，Gil-Henn H ... -  《-》

Ableson kinases negatively regulate invadopodia function and invasion in head and neck squamous cell carcinoma by inhibiting an HB-EGF autocrine loop.

Hayes KE ，Walk EL ，Ammer AG ，Kelley LC ，Martin KH ，Weed SA ... -  《-》

Phosphorylated cortactin recruits Vav2 guanine nucleotide exchange factor to activate Rac3 and promote invadopodial function in invasive breast cancer cells.

Breast carcinoma cells use specialized, actin-rich protrusions called invadopodia to degrade and invade through the extracellular matrix. Phosphorylation of the actin nucleation-promoting factor and actin-stabilizing protein cortactin downstream of the epidermal growth factor receptor-Src-Arg kinase cascade is known to be a critical trigger for invadopodium maturation and subsequent cell invasion in breast cancer cells. The functions of cortactin phosphorylation in this process, however, are not completely understood. We identify the Rho-family guanine nucleotide exchange factor Vav2 in a comprehensive screen for human SH2 domains that bind selectively to phosphorylated cortactin. We demonstrate that the Vav2 SH2 domain binds selectively to phosphotyrosine-containing peptides corresponding to cortactin tyrosines Y421 and Y466 but not to Y482. Mutation of the Vav2 SH2 domain disrupts its recruitment to invadopodia, and an SH2-domain mutant form of Vav2 cannot support efficient matrix degradation in invasive MDA-MB-231 breast cancer cells. We show that Vav2 function is required for promoting invadopodium maturation and consequent actin polymerization, matrix degradation, and invasive migratory behavior. Using biochemical assays and a novel Rac3 biosensor, we show that Vav2 promotes Rac3 activation at invadopodia. Rac3 knockdown reduces matrix degradation by invadopodia, whereas a constitutively active Rac3 can rescue the deficits in invadopodium function in Vav2-knockdown cells. Together these data indicate that phosphorylated cortactin recruits Vav2 to activate Rac3 and promote invadopodial maturation in invasive breast cancer cells.

Rosenberg BJ ，Gil-Henn H ，Mader CC ，Halo T ，Yin T ，Condeelis J ，Machida K ，Wu YI ，Koleske AJ ... -  《-》

Dissecting the functional domain requirements of cortactin in invadopodia formation.

Webb BA ，Jia L ，Eves R ，Mak AS ... -  《EUROPEAN JOURNAL OF CELL BIOLOGY》

Specific tyrosine phosphorylation sites on cortactin regulate Nck1-dependent actin polymerization in invadopodia.

Oser M ，Mader CC ，Gil-Henn H ，Magalhaes M ，Bravo-Cordero JJ ，Koleske AJ ，Condeelis J ... -  《-》