Regulation of metastasis by alpha V integrin and Src

点击翻译按钮获取中文摘要

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.