PTEN TUMOR SUPPRESSOR AND CELL CYCLE REGULATION

PTEN 肿瘤抑制剂和细胞周期调节

• 批准号: 2909850
• 负责人: HONG SUN
• 金额: $ 33.97万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2004-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2909850
• 关键词: 3T3 cells; SDS polyacrylamide gel electrophoresis; autoradiography; biological signal transduction; carcinogenesis; cell cycle; cell cycle proteins; cell growth regulation; embryonic stem cell; enzyme inhibitors; high performance liquid chromatography; immunoprecipitation; laboratory mouse; laboratory rabbit; nucleic acid sequence; oncoproteins; phosphatidylinositol 3 kinase; protein kinase; protein purification; protein structure function; tissue /cell culture; tumor suppressor proteins

Elucidation of tumor suppressor function provides much valuable insights into the mechanism of tumorigenesis. We have previously identified a novel phosphatase, TEP1, that shares substantial homology to several cytoskeletal proteins such as tensin. The gene encoding TEP1 is mapped to chromosome 10q23, a locus frequently deleted in human cancers. TEP1 is identical to the candidate tumor suppressor PTEN or MMAC1, which was isolated by positional cloning method. PTEN/MMAC1/TEP1 is deleted or mutated in many primary human cancers including glioblastma, endometric tumor, breast and prostate cancers and in several cancer predisposition syndromes such as Cowden disease. The broad, long term objective of this application is to elucidate the molecular mechanisms by which the cellular signaling pathways are linked to the regulatory processes for cell cycle progression and cell survival. In particular, this proposal is focused on investigating the mechanism by which the tumor suppressor protein PTEN functions to regulate cell cycle progression and how the inactivation of this tumor suppressor contributes to the genesis of human cancer. Our recent studies strongly suggest that in vivo, PTEN acts as a specific phosphatase towards phosphatidylinositol 3,4,5-trisphosphate (PIP3). We have generated the mouse embryonic stem cells in which the Pten gene was deleted by homologous recombination (Pten-/- cells). We have shown that Pten-/- cells contained elevated level of PIP3 and increased activation of Akt/PKB, a downstream signaling molecule in the PI 3-kinase pathway. Consequently, Pten-/- cells exhibited enhanced cell proliferation and cell survival. We further demonstrated that PTEN deletion caused advanced cell cycle progression into S-phase and a critical target for PTEN effect on cell cycle is p27KIP1, a CDK inhibitor. We propose to elucidate the molecular mechanism by which PTEN regulates p27 level and cell cycle progression. Our specific aims are: 1) To determine how the PTEN pathway regulates p27 level; 2) To analyze the PI 3-kinase downstream factors involved in regulation of p27; 3) To establish biochemical and molecular assays to identify the PTEN responsive factors that control p27; 4) To investigate the regulation of PTEN activity using structure and function analysis. The proposed research program in this application should provide novel insights into the molecular mechanisms that underlie the PTEN tumor suppressor function. Such knowledge should also help to provide a molecular basis for designing novel strategies for the diagnosis and treatment of human cancer.

肿瘤抑制功能的阐明为深入了解肿瘤发生机制提供了重要的理论依据。 我们以前已经确定了一种新的磷酸酶，TEP 1，共享大量的同源性，如张力蛋白的几种细胞骨架蛋白。 编码TEP 1的基因定位于染色体10 q23，这是一个在人类癌症中经常缺失的位点。 TEP 1与通过定位克隆方法分离的候选肿瘤抑制基因PTEN或MMAC 1相同。PTEN/MMAC 1/TEP 1在许多原发性人类癌症中缺失或突变，包括成胶质细胞瘤、子宫内膜癌、乳腺癌和前列腺癌，以及在几种癌症易感综合征如考登病中缺失或突变。 本申请的广泛、长期目标是阐明细胞信号传导途径与细胞周期进展和细胞存活的调节过程相关联的分子机制。 特别是，该提案的重点是调查的机制，肿瘤抑制蛋白PTEN的功能，以调节细胞周期的进展，以及如何失活的这种肿瘤抑制剂有助于人类癌症的发生。 我们最近的研究强烈表明，在体内，PTEN作为一种特异性磷酸酶对磷脂酰肌醇3，4，5-三磷酸（PIP 3）。 我们已经产生了小鼠胚胎干细胞，其中Pten基因被删除的同源重组（Pten-/-细胞）。 我们已经证明Pten-/-细胞含有升高水平的PIP 3和增加的Akt/PKB（PI 3-激酶途径中的下游信号分子）活化。 因此，Pten-/-细胞表现出增强的细胞增殖和细胞存活。 我们进一步证明了PTEN缺失导致细胞周期进展到S期，并且PTEN对细胞周期的作用的关键靶点是p27 KIP 1，一种CDK抑制剂。 本研究旨在阐明PTEN调控p27水平和细胞周期进程的分子机制。 我们的具体目标是：目的：1）明确PTEN通路对p27表达的调控机制; 2）分析P13激酶下游参与p27表达调控的因子; 3）建立生物化学和分子生物学方法鉴定调控p27表达的PTEN应答因子; 4）通过结构和功能分析研究PTEN活性的调控机制。 在这项申请中提出的研究计划应该提供新的见解的分子机制，PTEN肿瘤抑制功能的基础。 这些知识也有助于为设计诊断和治疗人类癌症的新策略提供分子基础。