Oncogenic Src requires a wild-type counterpart to regulate invadopodia maturation

Abstract

SummaryThe proto-oncogene Src tyrosine kinase (Src) is overexpressed in human cancers and is currently a target of anti-invasive therapies. Activation of Src is an essential catalyst of invadopodia production. Invadopodia are cellular structures that mediate extracellular matrix (ECM) proteolysis, allowing invasive cell types to breach confining tissue barriers. Invadopodia assembly and maturation is a multistep process, first requiring the targeting of actin-associated proteins to form pre-invadopodia, which subsequently mature by recruitment and activation of matrix metalloproteases (MMPs) that facilitate ECM degradation. We demonstrate that active, oncogenic Src alleles require the presence of a wild-type counterpart to induce ECM degradation at invadopodia sites. In addition, we identify the phosphorylation of the invadopodia regulatory protein cortactin as an important mediator of invadopodia maturation downstream of wild-type Src. Distinct phosphotyrosine-based protein-binding profiles in cells forming pre-invadopodia and mature invadopodia were identified by SH2-domain array analysis. These results indicate that although elevated Src kinase activity is required to target actin-associated proteins to pre-invadopodia, regulated Src activity is required for invadopodia maturation and matrix degradation activity. Our findings describe a previously unappreciated role for proto-oncogenic Src in enabling the invasive activity of constitutively active Src alleles.

Src binds cortactin through an SH2 domain cystine-mediated linkage

“…However, rescue of cortactin sh cells with cortactin TYM resulted in the formation of invadopodia structures with limited matrix degradation ability. These structures are likely pre-invadopodia as previously described (Kelley et al, 2010a;Oser et al, 2009). Rescue of cortactin sh cells with cortactin DCM failed to restore invadopodia/preinvadopodia formation and gelatin degradation.…”

Mechanisms of Invasion in Head and Neck Cancer

“…91 Intriguingly, although constitutively active Src induces invadopodium formation, wild-type Src expression is also needed in HNSCC cells for invadopodium-associated matrix degradation. 205 Abelson (Abl) kinase activity diminishes invadopodial ECM degradation in HNSCC cells: The inhibition of Abl and Arg by imatinib, an Abl family inhibitor, led to EGFR activation through increased HB-EGF production and shedding, and because of increased EGFR signaling, Src and ERK activity induced tyrosine and serine phosphorylation of cortactin. 55 These findings differ from a proposed model of EGFR-invadopodia signaling in breast cancer where elevated EGFR signaling induces Src activation, which subsequently leads to activation of Abl/Arg and tyrosine phosphorylation of cortactin by Abl/Arg.…”

The interplay between the proteolytic, invasive, and adhesive domains of invadopodia and their roles in cancer invasion

“…1A and B). This signaling event triggers the activation of c-src, 7,[64][65][66] PKC isoforms, [67][68][69][70] and eventually, the adaptor protein TKS5, 71 which plays a key role in early stages of the assembly of the actin machinery, TKS5 can then bind to Ptdlns(3,4)P 2 at the plasma membrane, promoting the recruitment of actin regulators such as the SH2/SH3-containing, signaling adaptor protein NCK1 to the membrane. 2 The exact temporal sequence of these events is still not elucidated.…”