Cytoskeletal Dynamics in Pancreatic Cancer Metastasis

描述（由申请人提供）：胰腺癌是一种预后极差的毁灭性疾病。起源于导管的肿瘤占胰腺肿瘤的95%，有很强的侵袭周围实质和转移到远端器官的倾向。目前，支持这些关键过程的分子机制尚不明确。众所周知，肌动蛋白细胞骨架在许多胰腺肿瘤中显著上调的受体酪氨酸激酶（RTKs）家族的刺激下起着重要作用并动态响应。本研究旨在研究RTKs激活肌动蛋白细胞骨架的戏剧性重组机制，从而改变细胞极性并导致细胞迁移、侵袭和转移。我们已经确定了一个关键的调控细胞骨架复合物在这些细胞组成；一种被称为动力蛋白（Dyn2）的大型机械化学GTPase，在人类胰腺肿瘤中显着上调，肌动蛋白交联蛋白cortacn，以及转化激酶Src，后者被rtk激活，结合并磷酸化Dyn2和cortacn。重要的是，我们已经证明这种复合物与肌动蛋白细胞骨架、细胞膜以及已知的与胰腺癌有关的致癌蛋白相关联，形成支持侵袭过程的“信号平台”。我们最近的手稿和未发表的观察结果为本研究的中心假设提供了强有力的支持：主要是Dyn2-Cort-Src复合物，与致癌蛋白1-actin和Rac一起，通过升高的RTK级联激活，介导肌动蛋白-质膜动力学，促进肿瘤胰腺小管细胞的侵袭和转移。本提案将利用应用于胰腺肿瘤细胞系的最先进的光学和分子方法，人类肿瘤样本的组织微阵列（TMA）技术，以及体内动物模型来确定该蛋白复合物增强胰腺肿瘤和转移的分子机制。本建议分为三个不同但相关的具体目标，这些目标将定义以下内容：首先，这些信号平台如何介导细胞表面rtk的大规模内在化，从而改变细胞信号级联；其次，Dyn2-Cort-Src复合物如何介导肿瘤细胞迁移和侵袭性的主要肌动蛋白重组；第三，肿瘤细胞粘附复合物如何形成和增殖，介导周围细胞外基质降解，促进转移。本研究将揭示分离细胞与人类肿瘤之间的密切关系，为理解胰腺肿瘤侵袭性、迁移性和致死性的分子机制提供新的信息。此外，它描述了使用新的，最近确定的药理学抑制剂的临床前试验。

DESCRIPTION (provided by applicant): Pancreatic cancer is a devastating disease with an exceptionally poor prognosis. Tumors of ductular origin comprise 95% of pancreatic neoplasms and have strong tendencies to invade surrounding parenchyma and metastasize to distal organs. Currently, the molecular mechanisms that support these critical processes are poorly defined. It is known that the actin cytoskeleton plays an important role and responds dynamically to stimulation by a family of Receptor Tyrosine Kinases (RTKs) that are upregulated significantly in many pancreatic tumors. This is a proposal to study the mechanisms by which RTKs activate dramatic reorganization of the actin cytoskeleton, which alters cell polarity and leads to cell migration, invasion, and metastasis. We have identified a key regulatory cytoskeletal complex in these cells composed of; a large mechanochemical GTPase called dynamin (Dyn2) that is markedly upregulated in human pancreatic tumors, the actin crosslinking protein cortactin, and the transforming kinase Src, which is activated by RTKs and binds and phosphorylates both Dyn2 and cortactin. Importantly, we have shown that this complex associates with the actin cytoskeleton, cellular membranes, as well as known oncogenic proteins implicated in pancreatic cancer to form "signaling platforms" that support the invasive process. Our recent manuscripts and unpublished observations provide strong support for the CENTRAL HYPOTHESIS of this study: mainly, the Dyn2-Cort-Src complex, in concert with the oncogenic proteins 1-actinin and Rac, is activated by elevated RTK cascades to mediate actin-plasma membrane dynamics that promote invasion and metastasis of neoplastic pancreatic ductular cells. This proposal will utilize state-of-the-art optical and molecular methods applied to pancreatic tumor cell lines, tissue micro-array (TMA) technology of human tumor samples, and in vivo animal models to define the molecular mechanisms by which this protein complex potentiates pancreatic neoplasia and metastasis. This proposal is organized into three distinct but related specific aims that will define the following; first, how these signaling platforms mediate large-scale internalization of RTKs from the cell surface to alter cell signaling cascades; second, how the Dyn2-Cort-Src complex mediates major actin reorganization in tumor cells that become migratory and invasive; and third, how tumor cell adhesion complexes form and proliferate to mediate degradation of the surrounding extracellular matrix to facilitate metastasis. This study will make close correlations between isolated cells and human tumors to provide novel information toward understanding the molecular mechanisms that make pancreatic tumors so aggressive, migratory, and lethal. In addition, it describes pre-clinical trials using novel, recently identified pharmacological inhibitors. PUBLIC HEALTH RELEVANCE: Pancreatic cancers are particularly lethal due to the aggressive way they spread and metastasize. This proposal will define some of the central mechanisms by which these tumor cells move away from the pancreas to invade peripheral organs by focusing on specific "oncogenic" proteins that are markedly "upregulated" in these cancers.