PTEN TUMOR SUPPRESSOR AND CELL CYCLE REGULATION

PTEN 肿瘤抑制剂和细胞周期调节

• 批准号: 6633295
• 负责人: HONG SUN
• 金额: $ 34.75万
• 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 2005-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6633295
• 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肿瘤发生机制提供了许多有价值的见解。 我们之前已经鉴定出一种新型磷酸酶 TEP1，它与张力蛋白等几种细胞骨架蛋白具有显着的同源性。 编码 TEP1 的基因被映射到染色体 10q23，这是人类癌症中经常缺失的一个位点。 TEP1与通过定位克隆方法分离的候选抑癌基因PTEN或MMAC1相同。 PTEN/MMAC1/TEP1 在许多原发性人类癌症中缺失或突变，包括胶质母细胞瘤、子宫内膜肿瘤、乳腺癌和前列腺癌，以及考登病等几种癌症易感综合征。 该应用的广泛、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的分子机制。 特别是，该提案重点研究肿瘤抑制蛋白 PTEN 调节细胞周期进程的机制，以及该肿瘤抑制蛋白的失活如何促进人类癌症的发生。 我们最近的研究强烈表明，在体内，PTEN 作为磷脂酰肌醇 3,4,5-三磷酸 (PIP3) 的特异性磷酸酶。 我们已经生成了通过同源重组删除 Pten 基因的小鼠胚胎干细胞（Pten-/- 细胞）。 我们已经表明，Pten-/- 细胞中 PIP3 水平升高，Akt/PKB（PI 3 激酶途径中的下游信号分子）激活增加。 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，PTEN 缺失导致细胞周期提前进入 S 期，PTEN 对细胞周期影响的关键靶点是 CDK 抑制剂 p27KIP1。 我们建议阐明 PTEN 调节 p27 水平和细胞周期进程的分子机制。 我们的具体目标是：1）确定PTEN通路如何调节p27水平； 2) 分析参与p27调节的PI 3激酶下游因子； 3) 建立生化和分子检测方法来鉴定控制 p27 的 PTEN 反应因子； 4)通过结构和功能分析研究PTEN活性的调节。 本申请中提出的研究计划应该为 PTEN 肿瘤抑制功能的分子机制提供新的见解。 这些知识还应该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。