Eph Kinase Signaling in Prostate Cancer

描述(由申请人提供) 这项提议的长期目标是描述分子机制。 Eph对前列腺上皮细胞迁移的有效抑制作用 受体酪氨酸激酶。细胞迁移涉及几个关键步骤 在肿瘤转移过程中，与前列腺癌有直接的相关性 体外运动与体内转移潜能之间的关系。使用PC-3细胞作为 一个模型系统，申请人的实验室发现，EphA2激酶激活 有效地抑制了向纤维连接蛋白和趋化蛋白的趋化运动 对表皮生长因子和肝细胞生长因子的运动。抑制作用 与整合素亲和力的抑制和去磷酸化有关 和催化灭活粘着斑激酶(FAK)，这是一种细胞质 酪氨酸激酶在细胞运动调节中起关键作用。EphA2 物理上与FAK相关，复合体在EphA2上解离 激活。SHP-2蛋白酪氨酸磷酸酶(PTPase)是一过性 被招募到激活的EphA2，并代表一个候选PTPase 与FAK去磷酸化有关。这些发现定义了一种新的信号 负向调节前列腺亲和趋化性的途径 上皮细胞。这项提议的重点是检验FAK的假设 是EphA2激酶的下游效应器。在具体目标1中，区域和 EphA2和FAK上负责其交互的站点将使用 缺失和定点突变。EphA2/FAK基因缺失突变株 协会将被用来评估 与负性调节细胞迁移的关联b phA2激酶。 特异性目标2旨在研究FAK去磷酸化和 SHP-2在EphA2信号中的招募使用分子和遗传方法。 鉴于细胞运动在前列腺癌转移中的基础作用， 拟议研究的完成将揭示一个自然存在的 关闭细胞迁移的信号通路，并可能导致新的 预防和治疗前列腺癌转移的策略。

DESCRIPTION (Provided by the applicant) The long-term goal of this proposal is to characterize the molecular mechanisms underlying potent inhibition of prostatic epithelial cell migration by Eph receptor tyrosine kinases. Cell migration is involved in several critical steps during tumor metastasis; for prostate cancer there is a direct correlation between motility in vitro and metastatic potential in vivo. Using PC-3 cells as a model system, the applicant's laboratory found that EphA2 kinase activation potently inhibited both haptotactic motility toward fibronectin and chemotactic motility toward epidermal and hepatocyte growth factors. The inhibitory effects were correlated with suppression of integrin affinity, and dephosphorylation and catalytic inactivation of focal adhesion kinase (FAK), a cytoplasmic tyrosine kinase critically involved in cell motility regulation. EphA2 physically associated with FAK and the complex was dissociated upon EphA2 activation. Shp-2 protein tyrosine phosphatase (PTPase) was transiently recruited to the activated EphA2, and represented one candidate PTPase implicated in FAK dephosphorylation. These findings defined a novel signaling pathway that negatively regulates haptotaxis and chemotaxis of prostatic epithelial cells. The focus of this proposal is to test the hypothesis that FAK is a downstream effector of EphA2 kinase. In Specific Aim 1, the regions and sites on EphA2 and FAK responsible for their interaction will be mapped using deletion and site-directed mutagenesis. Mutants deficient in EphA2/FAK association will e used to assess the functional significance of the association in the negative regulation of cell migration b phA2 kinase. Specific Aim 2 is designed to investigate the role of FAK dephosphorylation and Shp-2 recruitment in EphA2 signaling using molecular and genetic approaches. Given the fundamental role of cell motility in prostate cancer metastasis, completion of the proposed studies will shed light on a naturally-existing signaling pathway that turns off cell migration, and may lead to novel strategies in preventing and treating prostate cancer metastasis.