Regulation of metastasis by alpha V integrin and Src

描述(由申请人提供)：整合素和生长因子受体以一种合作的方式发挥作用，调节细胞行为。在之前的资金周期中，我们已经开始探索胰腺癌细胞中的一个信号模块，它似乎调节这些细胞的转移特性。我们发现，表皮生长因子受体(EGFR)和整合素avb5一起促进了Src激酶信号，这似乎直接调节了人和小鼠胰腺癌细胞的侵袭特性。我们已经确定了两条肿瘤细胞在体外迁移的途径，这两条途径可以通过它们对Src激酶活性的不同依赖来区分。B1整合素介导的细胞在纤维连接蛋白、胶原和层粘连蛋白上的迁移不依赖于Src，而整合素avb5介导的细胞在玻璃体连接蛋白上的迁移依赖于Src。在初步结果中，我们发现在体内原位和自发性胰腺癌细胞转移模型中，EGFR/Src/avb5信号模块启动了导致肿瘤细胞侵袭的级联反应。我们选择了匹配的原代和转移胰腺细胞系，发现EGFR的激活或过表达以及整合素avb5的连接似乎诱导了Src活性和下游信号转导，导致这些细胞的侵袭行为增加。我们发现，通过活体多光子成像测量，表达增加的Src激酶活性的胰腺癌细胞从原发肿瘤向宿主基质深处侵袭，而具有最低Src活性的原发肿瘤仍然局限在肿瘤实质内。在这个提案中，我们将描述EGFR/Src/avb5信号促进侵袭和转移的机制。我们将探索特定底物的Src酪氨酸磷酸化如何影响这种侵袭行为。这些研究将集中在Src如何不仅激活细胞迁移机制，而且如何促进肿瘤细胞黏附连接的解偶联。最后，我们将探索这种EGFR/avb5/Src信号模块对转移性胰腺癌细胞的药理和/或遗传破坏如何在体内逆转其转移表型。在这种情况下，我们将评估这些靶点在原位胰腺癌模型以及自发性原发和转移性胰腺癌的遗传模型中的可能治疗相关性。这些研究应该提供对胰腺癌侵袭行为的信号级联的分子洞察力。

DESCRIPTION (provided by applicant): Integrins and growth factor receptors function in a cooperative manner to regulate cellular behavior. During the previous funding cycle, we have begun to explore a signaling module in pancreatic carcinoma cells that appears to regulate the metastatic properties of these cells. We found that epidermal growth factor receptor (EGFR) together with the integrin avb5 promotes Src kinase signaling that appears to directly regulate the invasive properties of both human and murine pancreatic tumor cells. We have identified two pathways of tumor cell migration in vitro that can be distinguished by their differential dependence on Src kinase activity. Cell migration on fibronectin, collagen, and laminin mediated by b1 integrins is independent of Src, while migration on vitronectin mediated by integrin avb5 depends on Src. In Preliminary Results, we show that the EGFR/Src/avb5 signaling module initiates a cascade leading to tumor cell invasion in both orthotopic and spontaneous pancreatic cancer cell metastasis models in vivo. We have selected matched primary and metastatic pancreatic cell lines, and found that activation or overexpression of EGFR together with ligation of integrin avb5 appears to induce Src activity and downstream signaling leading to increased invasive behavior of these cells. We find that pancreatic cancer cells expressing increased Src kinase activity invade from the primary tumor deep into the host stroma while primary tumors with minimal Src activity remain confined within the tumor parenchyma as measured by intravital multi-photon imaging. In this proposal, we will characterize the mechanism by which EGFR/Src/avb5 signaling promotes invasion and metastasis. We will explore how Src tyrosine phosphorylation of specific substrates influences this invasive behavior. These studies will focus on how Src not only activates the cell migration machinery, but how it promotes the uncoupling of tumor cell adherens junctions. Finally we will explore how pharmacological and/or genetic disruption of this EGFR/avb5/Src signaling module on metastatic pancreatic cancer cells reverses their metastatic phenotype in vivo. In this case, we will evaluate the possible therapeutic relevance of these targets in orthotopic pancreatic cancer models, as well as a genetic model of spontaneous primary and metastatic pancreatic cancer. These studies should provide molecular insight into a signaling cascade that appears to contribute to the invasive behavior of pancreatic carcinoma.