Department of Neurobiology and Anatomy, Program in Cancer Cell Biology, Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, West Virginia 26506-9300, USA.
J Cell Sci. 2010 Nov 15;123(Pt 22):3923-32. doi: 10.1242/jcs.075200. Epub 2010 Oct 27.
The 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.
原癌基因 Src 酪氨酸激酶（Src）在人类癌症中过度表达，目前是抗侵袭治疗的靶点。Src 的激活是侵袭伪足产生的关键催化剂。侵袭伪足是一种介导细胞外基质（ECM）蛋白水解的细胞结构，使侵袭性细胞类型能够突破限制组织的屏障。侵袭伪足的组装和成熟是一个多步骤的过程，首先需要将肌动蛋白相关蛋白靶向到形成前侵袭伪足，随后通过募集和激活基质金属蛋白酶（MMPs）来成熟，从而促进 ECM 降解。我们证明，活性致癌 Src 等位基因需要野生型对应物的存在才能在侵袭伪足部位诱导 ECM 降解。此外，我们确定侵袭伪足调节蛋白 cortactin 的磷酸化是野生型 Src 下游侵袭伪足成熟的重要介质。通过 SH2 结构域阵列分析鉴定了在形成前侵袭伪足和成熟侵袭伪足的细胞中独特的基于磷酸酪氨酸的蛋白质结合图谱。这些结果表明，尽管升高的 Src 激酶活性是将肌动蛋白相关蛋白靶向到前侵袭伪足所必需的，但调节的 Src 活性是侵袭伪足成熟和基质降解活性所必需的。我们的发现描述了原癌基因 Src 在使组成性激活的 Src 等位基因具有侵袭活性方面的先前未被认识到的作用。
