The role of actin polymerization in tumor metastasis

肌动蛋白聚合在肿瘤转移中的作用

• 批准号: 6777051
• 负责人: Steven ZHAN
• 金额: $ 41.72万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6777051
• 关键词: actin binding protein; actins; biological signal transduction; cell adhesion; cell migration; cell motility; guanine nucleotide binding protein; intermolecular interaction; metastasis; neoplasm /cancer; oncogenes; pathologic process; polymerization; protein localization; protein protein interaction; protein structure function; protein tyrosine kinase; transfection; yeast two hybrid system

DESCRIPTION: (provided by applicant) The long-term goal of this application is to understand the molecular mechanism ot tumor metastasis. Prior works have established that amplification of the chromosome 11q13, which occurs frequently in breast cancer, head and neck squamous carcinomas and bladder cancer, results in overexpression of cortactin or EMS 1, a prominent substrate of protein tyrosine kinase Src with potential to associate with actin filaments. Patients with gene amplification of cortactin tend to have poor prognosis and increased possibility of relapse. However, the mechanism by which cortactin contributes to tumor progression is still unknown. There has been accumulated evidence that cortactin is implicated in the modulation of cell cytoskeletal changes associated with cell motility and cell shape changes. Our recent study further demonstrated that cortactin plays an important role in actin polymerization via interaction with Arp2/3 complex, a key protein machinery to initiate actin polymerization within cells. Furthermore, cortactin modulates the activity of Arp2/3 complex for actin nucleation and actin branching, two important steps in the formation of cell leading edge structures. We also found that overexpression of wild-type cortactin can enhance cell motility in vitro and facilitate tumor metastasis in vivo, whereas overexpression of cortactin mutants either in tyrosine phosphorylation or Arp2/3 binding can impair cell migration and bone metastasis. Based on these observations, we hypothesize that actin polymerization mediated by Arp2/3 complex and cortactin plays an important role in tumor metastasis. To test this hypothesis, we propose to delineate the detailed interactions among Arp2/3 complex and cortactin, explore the regulation of cortactin/Arp2/3 complex by Src, PIP2 and other cellular factors, and to test the hypothesis whether or not inhibition of actin polymerization by disruption of these interactions would be effectively able to compromise metastasis in vivo. Thus, the specific aims for this application include: (1) Characterization of the mechanism by which cortactin activates the activity of Arp2/3 complex for actin nucleation and branching. We will characterize the structural basis for the interactions between cortactin and Arp2/3 complex, examine the mechanism by which cortactin enhances actin nucleation and promotes and stabilizes actin branching. (2) Study of the regulation of cortactin/Arp2/3-mediated actin nucleation and branching. We will assess the effect of Src and PIP2 on the actin nucleation and branching mediated by cortactin/Arp2/3 complex in vitro, and search for other cellular factor(s) through which Src, PIP2, Cdc42 and Rac may regulate the function of cortactin/Arp2/3 complex. (3) Analysis of the effects of the mutants derived from Arp2/3 and cortactin on tumor metastasis. We will introduce using retrovirus functional peptides derived from Arp2/3 and cortactin that can disrupt or enhance actin polymerization into MDA-MB-23 1 tumor cells. Next, we will evaluate the motility and metastatic potentials of these cells both in vitro and in vivo.

描述：（由申请人提供）本申请的长期目标是 了解肿瘤转移的分子机制。之前的作品有 确定了染色体 11q13 的扩增，这种情况经常发生 在乳腺癌、头颈鳞癌和膀胱癌中的结果 Cortactin 或 EMS 1（一种重要的蛋白质底物）的过度表达 酪氨酸激酶 Src 具有与肌动蛋白丝相关的潜力。患者 Cortactin 基因扩增往往预后不良且增加 复发的可能性。然而，cortactin 的作用机制 其对肿瘤进展的影响尚不清楚。已经积累的证据表明 Cortactin 参与细胞骨架变化的调节 与细胞运动和细胞形状变化有关。我们最近的进一步研究 证明 Cortactin 在肌动蛋白聚合中发挥重要作用 与 Arp2/3 复合物相互作用，Arp2/3 复合物是启动肌动蛋白的关键蛋白质机制 细胞内聚合。此外，cortactin 还调节 Arp2/3 复合物负责肌动蛋白成核和肌动蛋白分支，这是肌动蛋白成核和肌动蛋白分支的两个重要步骤 细胞前缘结构的形成。我们还发现 野生型 Cortactin 的过度表达可以增强细胞的体外运动能力 促进肿瘤在体内的转移，而cortactin的过度表达 酪氨酸磷酸化或 Arp2/3 结合突变体可能损害细胞 迁移和骨转移。根据这些观察，我们假设 由 Arp2/3 复合物和 cortactin 介导的肌动蛋白聚合发挥着 在肿瘤转移中发挥重要作用。为了检验这个假设，我们建议 描绘 Arp2/3 复合物和 cortactin 之间的详细相互作用，探索 Src、PIP2 和其他细胞对 cortactin/Arp2/3 复合物的调节 因素，并检验肌动蛋白是否受到抑制的假设 通过破坏这些相互作用的聚合将有效地能够 损害体内转移。因此，该应用程序的具体目标 包括：（1）cortactin激活机制的表征 Arp2/3 复合物对肌动蛋白成核和分支的活性。我们将 表征 cortactin 和之间相互作用的结构基础 Arp2/3 复合体，检查 cortactin 增强肌动蛋白的机制 成核并促进和稳定肌动蛋白分支。 (2) 研究 cortactin/Arp2/3 介导的肌动蛋白成核和分支的调节。我们将 评估 Src 和 PIP2 对肌动蛋白成核和分支的影响 体外由 cortactin/Arp2/3 复合物介导，并寻找其他细胞 Src、PIP2、Cdc42 和 Rac 可能调节功能的因子 cortactin/Arp2/3 复合物。 (3) 衍生突变体的效果分析 Arp2/3 和 cortactin 对肿瘤转移的影响。我们将介绍使用 源自 Arp2/3 和 cortactin 的逆转录病毒功能肽 破坏或增强肌动蛋白聚合到 MDA-MB-23 1 肿瘤细胞中。接下来，我们 将评估这些细胞的运动性和转移潜力 体外和体内。