Cytoskeletal Dynamics in Pancreatic Cancer Metastasis

项目摘要/摘要 胰腺癌是一种极具破坏性的疾病，预后极差。起源于导管的肿瘤 占胰腺肿瘤的95%，有很强的侵犯周围实质和 转移到远端器官。目前，支持这些关键过程的分子机制是 定义不明确。已知肌动蛋白细胞骨架起着重要作用，并动态地对 受体酪氨酸激酶(RTK)家族的刺激作用在许多 胰腺肿瘤。这是一项研究RTK激活戏剧性重组的机制的建议 肌动蛋白细胞骨架，改变细胞极性，导致细胞迁移、侵袭和转移。我们 已经在这些细胞中发现了一个关键的调控细胞骨架复合体，它由一种大型机械力化学物质组成 一种名为Dynamin(Dyn2)的GTP酶，在人胰腺肿瘤中显著上调，即肌动蛋白 交联蛋白Cortactin，以及由RTKs激活并结合和 同时使dyn2和Cortactin磷酸化。重要的是，我们已经证明了这种复合体与 肌动蛋白细胞骨架、细胞膜以及与胰腺癌有关的已知致癌蛋白 形成支持入侵过程的“信号平台”。我们最近的手稿和未出版的 观察结果为本研究的中心假说提供了强有力的支持：主要是DYN2-CORT-Src 与致癌蛋白肌动蛋白和RAC结合的复合体，由升高的RTK级联激活以 介导肌动蛋白-质膜动力学促进胰腺肿瘤侵袭转移 导管细胞。这项建议将利用最先进的光学和分子方法应用于胰腺 肿瘤细胞系、人类肿瘤样本的组织微阵列(TMA)技术和体内动物模型 明确该蛋白复合体增强胰腺肿瘤和胰腺癌的分子机制 转移。这项提案分为三个不同但相关的具体目标，它们将界定以下内容； 首先，这些信号平台如何从细胞表面介导RTK的大规模内化来改变 细胞信号级联；第二，Dy2-Cort-Src复合体如何在肿瘤中介导主要的肌动蛋白重组 细胞的迁移和侵袭；第三，肿瘤细胞黏附复合体的形成和增殖 调节周围细胞外基质的降解，促进肿瘤转移。这项研究将使 分离的细胞与人类肿瘤之间的密切关联为理解提供新的信息 胰腺肿瘤如此具有侵袭性、迁移性和致命性的分子机制。此外，它还 描述了使用新的，最近发现的药理抑制剂的临床前试验。

Project Summary/Abstract 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 Our recent manuscripts and unpublished observations provide strong support for the CENTRAL HYPOTHESIS of this study: mainly, the Dyn2-Cort-Src complex, in concert with the oncogenic proteins ¿-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.