PTEN Deficiency and Tumor Development

PTEN 缺乏和肿瘤发展

• 批准号: 7730801
• 负责人: YUXIN YIN
• 金额: $ 33.84万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-17 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7730801
• 关键词: 1-Phosphatidylinositol 3-Kinase; Affect; Age; Aneuploidy; Applications Grants; Biological Assay; Bub1 protein; C-terminal; Cell division; Cells; Chromatin; Chromosomal Instability; Chromosomal Stability; Chromosome Segregation; Chromosome abnormality; Chromosomes; Cytoplasm; Data; Defect; Development; Dominant-Negative Mutation; E2F1 gene; Embryo; Ensure; Exhibits; Fibroblasts; Frequencies; Functional disorder; Genes; Genome; Genome Stability; Genomic Instability; Goals; Human; Impairment; In Vitro; Kinetochores; Knock-in Mouse; Knockout Mice; Lead; Light; Location; Lymphocyte; Maintenance; Malignant Neoplasms; Mediating; Mitosis; Mitotic; Mitotic Checkpoint; Mitotic spindle; Mitotic/Spindle Checkpoint; Modeling; Multiple Hamartoma Syndrome; Mutate; Mutation; N-terminal; Nuclear; Null Lymphocytes; PTEN gene; Pathway interactions; Patients; Phosphoric Monoester Hydrolases; Play; Principal Investigator; Process; Proteins; Regulation; Research; Role; Testing; Transcriptional Regulation; Tumor Suppression; Tumor Suppressor Proteins; Yin; base; chromatin immunoprecipitation; gain of function; in vivo; insight; interest; mouse model; mutant; novel; prevent; programs; promoter; public health relevance; response; segregation; therapeutic development; tumor; tumorigenesis

DESCRIPTION (provided by applicant): PTEN Deficiency and Tumor Development PTEN is one of the most frequently mutated genes in human cancer. We have previously demonstrated that PTEN plays an essential role in the maintenance of genomic stability and that PTEN controls genome integrity through multiple mechanisms. The mitotic checkpoint is the most important mechanism for ensuring accurate chromosome segregation during cell division. Our preliminary data show that knockdown of PTEN causes severe mitotic misalignment and increases the frequency of monopolar and multipolar spindles, suggesting that PTEN deficiency impairs kinetochore congression and spindle bipolarity. Moreover, disruption of Pten eliminates the mitotic checkpoint response to spindle damage. Of significant interest was our finding that the levels of Bub1 and aurora B which are two critical mitotic checkpoint regulators are reduced in Pten null cells. In this grant application, we propose that PTEN plays a critical role in mitotic checkpoint control and spindle assembly. Our first specific aim is to characterize how PTEN deficiency affects kinetochore functions, spindle assembly and mitotic checkpoint activity. To do so, we will identify potential kinetochore or spindle factors physically associated with PTEN during mitosis. We will also determine whether wild-type PTEN can correct mitotic errors and restore the mitotic checkpoint. Our second specific aim is to determine whether the phosphatase activity of PTEN is necessary for its mitotic function and further define the functional domain of PTEN responsible for bipolar spindle assembly and the mitotic checkpoint. A variety of PTEN mutants with and without the N-terminal phosphatase domain will be tested for their ability to establish spindle bipolarity, sustain the expression levels of checkpoint proteins, and maintain a functional mitotic checkpoint. Our third specific aim is to explore the mechanism of how PTEN participates in the regulation of Bub1 and aurora B in synergy with E2F-1. Our preliminary chromatin immunoprecipitation assays identified both PTEN and E2F-1 on the mitotic gene promoter, which suggests there is functional cooperation of PTEN and E2F-1 on chromatin. We will therefore determine how PTEN acts on chromatin to modulate the transcriptional regulation of mitotic genes by E2F-1. Our final specific aim will be to further evaluate the role of PTEN in controlling the mitotic checkpoint and chromosomal stability using a Cowden syndrome model where PTEN is inherently mutated. We will examine the mitotic checkpoint activity in human lymphocytes with mutant PTEN. We will characterize the gain of function of PTEN mutants and determine whether these dominant-negative PTEN mutants disrupt the mitotic checkpoint and induce chromosome instability. Finally, we will use a PTEN189 mutant knock-in mouse model to determine whether the PTEN189 mutation causes genomic instability and results in tumorigenesis. Successful completion of this project will define PTEN as a controller of the spindle checkpoint and a guardian of the genome. New findings from this project may provide insights into the mechanism whereby PTEN deficiency and consequent mitotic dysfunction lead to tumorigenesis. PUBLIC HEALTH RELEVANCE: PTEN Deficiency and Tumor Development Narrative The PTEN tumor suppressor is frequently mutated in a variety of human cancers. Loss of PTEN leads to tumorigenesis in mouse models. The mitotic checkpoint is a major mechanism for ensuring chromosome inheritance and preventing malignancy. This project will explore novel functions of nuclear PTEN in maintaining genomic stability by revealing its critical role in spindle assembly and chromosome segregation. New findings from this study will answer the fundamental question of how PTEN deficiency impairs the mitotic surveillance machinery, leading to tumor development. Identification of the PTEN-mitotic pathway may offer a profound implication for development of therapeutic strategies against tumorigenesis.

描述（由申请人提供）：PTEN 缺陷和肿瘤发展 PTEN 是人类癌症中最常见的突变基因之一。我们之前已经证明 PTEN 在维持基因组稳定性方面发挥着重要作用，并且 PTEN 通过多种机制控制基因组完整性。有丝分裂检查点是确保细胞分裂过程中染色体准确分离的最重要机制。我们的初步数据表明，PTEN 的敲低会导致严重的有丝分裂错位，并增加单极和多极纺锤体的频率，表明 PTEN 缺陷会损害着丝粒大会和纺锤体双极性。此外，Pten 的破坏消除了有丝分裂检查点对纺锤体损伤的反应。值得注意的是，我们发现 Bub1 和 aurora B 这两个关键的有丝分裂检查点调节因子的水平在 Pten 无效细胞中降低。在本次拨款申请中，我们提出 PTEN 在有丝分裂检查点控制和纺锤体组装中发挥着关键作用。我们的第一个具体目标是确定 PTEN 缺陷如何影响着丝粒功能、纺锤体组装和有丝分裂检查点活性。为此，我们将确定有丝分裂过程中与 PTEN 物理相关的潜在动粒或纺锤体因素。我们还将确定野生型 PTEN 是否可以纠正有丝分裂错误并恢复有丝分裂检查点。我们的第二个具体目标是确定 PTEN 的磷酸酶活性是否对其有丝分裂功能是必需的，并进一步确定 PTEN 负责双极纺锤体组装和有丝分裂检查点的功能域。将测试具有和不具有 N 末端磷酸酶结构域的各种 PTEN 突变体建立纺锤体双极性、维持检查点蛋白表达水平和维持功能性有丝分裂检查点的能力。我们的第三个具体目标是探索PTEN如何与E2F-1协同参与Bub1和aurora B的调节机制。我们的初步染色质免疫沉淀分析在有丝分裂基因启动子上鉴定出了 PTEN 和 E2F-1，这表明 PTEN 和 E2F-1 在染色质上存在功能合作。因此，我们将确定 PTEN 如何作用于染色质以调节 E2F-1 对有丝分裂基因的转录调控。我们最终的具体目标是使用 PTEN 固有突变的 Cowden 综合征模型进一步评估 PTEN 在控制有丝分裂检查点和染色体稳定性中的作用。我们将检查具有突变 PTEN 的人淋巴细胞的有丝分裂检查点活性。我们将表征 PTEN 突变体的功能获得，并确定这些显性失活 PTEN 突变体是否破坏有丝分裂检查点并诱导染色体不稳定。最后，我们将使用PTEN189突变敲入小鼠模型来确定PTEN189突变是否会导致基因组不稳定并导致肿瘤发生。该项目的成功完成将把PTEN定义为纺锤体检查点的控制者和基因组的守护者。该项目的新发现可能有助于深入了解 PTEN 缺陷和随之而来的有丝分裂功能障碍​​导致肿瘤发生的机制。公共卫生相关性：PTEN 缺乏和肿瘤发展叙述 PTEN 肿瘤抑制因子在多种人类癌症中经常发生突变。 PTEN 的缺失会导致小鼠模型中的肿瘤发生。有丝分裂检查点是确保染色体遗传和预防恶性肿瘤的主要机制。该项目将通过揭示核 PTEN 在纺锤体组装和染色体分离中的关键作用，探索核 PTEN 在维持基因组稳定性方面的新功能。这项研究的新发现将回答 PTEN 缺陷如何损害有丝分裂监视机制，从而导致肿瘤发展的基本问题。 PTEN 有丝分裂途径的鉴定可能对开发抗肿瘤发生的治疗策略具有深远的意义。