Functional role of p68 tyrosine phosphorylation in cancer metastasis

描述（由申请人提供）：我们观察到，与非转移性癌细胞系和组织样品相比，在转移性癌细胞系和组织样品中，p68 RNA解旋酶在酪氨酸残基处获得显著更高水平的磷酸化。P68在非癌组织中不被磷酸化。我们还发现p68在酪氨酸593处的磷酸化是上皮-间充质转化（EMT）所必需的，EMT是癌症转移的关键事件。磷酸化的p68通过促进β-catenin核转位和激活Snail基因的转录而促进EMT。我们的假设是，磷酸化p68是一个新的和重要的调节因子，在促进EMT和肿瘤进展/转移中起重要作用。本研究计划的目标有两个方面：（1）全面了解磷酸化p68促进EMT的分子机制，（2）广泛测试磷酸化p68在促进癌症转移中的作用。在具体的目标1中，我们提出实验来测试p68磷酸化在异种移植小鼠模型和癌症患者的组织样品中促进癌症转移的作用。在具体目标2中，我们设计实验来阐明磷酸化p68激活Snail基因转录的机制。我们将测试磷酸化p68是否使用其蛋白质依赖性ATP酶活性从Snail启动子处的重塑和脱乙酰化复合物（NuRD）中“置换”HDAC 1。大多数癌症相关死亡是癌症转移的结果。虽然肿瘤转移的过程已经有了一个大致的轮廓，但其具体的机制还远未完全了解，尤其是参与肿瘤转移各个步骤的细胞因子。在具体目标3中，我们提出实验来测试磷酸化p68是否主动地将细胞质β-连环蛋白“转运”到细胞核。我们的研究将揭示一个新的分子因子，参与癌症转移。了解磷酸化p68的功能作用将最终应用于开发新的策略，以诊断/预后和治疗癌症转移。

DESCRIPTION (provided by applicant): We have: observed that p68 RNA helicase acquired substantially higher level of phosphorylation(s) at tyrosine residues in both metastatic cancer cell lines and tissue samples compared to that in non-metastatic cancer cell lines and tissue samples. P68 is not phosphorylated in non-cancerous tissues. We also found that phosphorylation of p68 at tyrosine 593 is required for epithelial-mesenchymal-transition (EMT), a critical event for cancer metastasis. The phosphorylated p68 promotes EMT by facilitating beta-catenin nuclear translocation and activating transcription of Snail gene. Our hypothesis is that the phosphorylated p68 is a new and important regulatory factor that plays important role(s) in promoting EMT and tumor progression/metastasis. The goals of this research proposal are two fold: (1) to gain a comprehensive understanding of the molecular mechanism by which the phospho-p68 promotes EMT, and (2) to extensively test the role of the phospho-p68 in promoting cancer metastasis. In specific aim 1, we propose experiments to test the role of the p68 phosphorylation in promoting cancer metastasis both in xenograft mice model and in tissue samples from cancer patients. In specific aim 2, we design experiments to elucidate the mechanism by which the phospho-p68 activates Snail gene transcription. We will test whether the phospho- p68 use its protein-dependent ATPase activity to 'displace' HDAC1 from remodeling and deacetylation complex (NuRD) at Snail promoter. Most cancer-related deaths are the consequence of the cancer metastasis. Although an outline picture about the process of cancer metastasis is emerge, the detailed mechanism is still far beyond fully understanding, especially the cellular factors that contribute to each steps of cancer metastasis. In specific aim 3, we propose experiments to test whether the phospho-p68 actively 'transports' cytoplasmic beta-catenin to the nucleus. Our study will uncover a new molecular factor that is involved in cancer metastasis. Understanding the functional role of phospho-p68 will ultimately be applied to develop new strategies to the diagnosis/prognosis and treatment for cancer metastasis.