Arg kinase mediates CXCL12/CXCR4-induced invadopodia formation and invasion of glioma cells

Compared with noninvasive tumor cells, glioma cells overexpress chemokine receptor type 4 (CXCR4), which exhibits significantly greater expression in invasive tumor cells than in noninvasive tumor cells. C-X-C motif chemokine ligand 12 (CXCL12, also known as stromal derived factor-1, SDF-1) and its cell surface receptor CXCR4 activate a signaling axis that induces the expression of membrane type-2 matrix metalloproteinase (MT2-MMP), which plays a pivotal role in the invasion and migration of various cancer cells; however, the specific mechanism involved in this is unclear. Recently, studies have shown that invadopodia can recruit and secrete related enzymes, such as matrix metalloproteinases (MMPs), to degrade the surrounding extracellular matrix (ECM), promoting the invasion and migration of tumor cells. Phosphorylated cortactin (pY421-cortactin) is required for the formation and maturation of invadopodia, but the upstream regulatory factors and kinases involved in phosphorylation have not been elucidated. In this study, we found that CXCL12/CXCR4 was capable of inducing glioma cell invadopodia formation, probably by regulating cortactin phosphorylation. The interaction of cortactin and Arg (also known as Abl-related nonreceptor tyrosine kinase, ABL2) in glioma cells was demonstrated. The silencing of Arg inhibited glioma cell invadopodia formation and invasion by blocking cortactin phosphorylation. Moreover, CXCL12 could not induce glioma cell invasion in Arg-knockdown glioma cells. Based on these results, it can be concluded that Arg mediates CXCL12/CXCR4-induced glioma cell invasion, and CXCL12/CXCR4 regulates invadopodia maturation through the Arg-cortactin pathway, which indicates that Arg could be a candidate therapeutic target to inhibit glioma cell invasion.