Functional role of p68 tyrosine phosphorylation in cancer metastasis

描述（由申请人提供）：我们观察到p68 RNA解旋酶在转移性癌细胞系和组织样本中酪氨酸残基的磷酸化水平明显高于非转移性癌细胞系和组织样本。P68在非癌组织中不被磷酸化。我们还发现p68酪氨酸593位点的磷酸化是上皮-间质转化（EMT）所必需的，这是癌症转移的一个关键事件。磷酸化的p68通过促进β -连环蛋白核易位和激活蜗牛基因转录来促进EMT。我们的假设是磷酸化的p68是一个新的重要调控因子，在促进EMT和肿瘤进展/转移中起重要作用。本课题的研究目标有两个方面：(1)全面了解phospho-p68促进EMT的分子机制；(2)广泛检测phospho-p68在促进肿瘤转移中的作用。在特定的目的1中，我们提出了在异种移植小鼠模型和癌症患者组织样本中测试p68磷酸化在促进癌症转移中的作用的实验。在特定目标2中，我们设计了实验来阐明磷酸化p68激活蜗牛基因转录的机制。我们将测试磷酸- p68是否使用其蛋白质依赖性atp酶活性来“取代”HDAC1在蜗牛启动子上的重塑和去乙酰化复合体（NuRD）。大多数癌症相关死亡是癌症转移的结果。虽然对肿瘤转移的过程已经有了大致的了解，但其具体的机制，特别是对影响肿瘤转移每一步的细胞因子的了解还远远不够。在具体目标3中，我们提出了实验来测试phospho-p68是否主动将细胞质β -连环蛋白“运输”到细胞核。我们的研究将揭示一个新的参与癌症转移的分子因子。了解phospho-p68的功能作用将最终应用于癌症转移的诊断、预后和治疗的新策略。

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.