PTEN Deficiency and Tumor Development

PTEN 缺乏和肿瘤发展

• 批准号: 7933905
• 负责人: YUXIN YIN
• 金额: $ 34.47万
• 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/7933905
• 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缺失与肿瘤发展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中起重要作用，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基因的缺失会导致严重的有丝分裂失调，增加单极和多极纺锤体的频率，这表明PTEN基因的缺失会损害着丝点的形成和纺锤体的双极性。此外，Pten的破坏消除了对纺锤体损伤的有丝分裂检查点反应。值得注意的是，我们发现在Pten无细胞中，两个关键的有丝分裂检查点调节因子Bub1和aurora B的水平降低。在这项拨款申请中，我们提出PTEN在有丝分裂检查点控制和纺锤体组装中起关键作用。我们的第一个具体目标是描述PTEN缺陷如何影响着丝点功能，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物理相关的潜在着丝点或纺锤体因子。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要的，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。多种具有或不具有n端磷酸酶结构域的PTEN突变体将被测试其建立纺锤体双极性、维持检查点蛋白的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的调控机制。我们的初步染色质免疫沉淀实验在有丝分裂基因启动子上发现了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，通过E2F-1调节有丝分裂基因的转录调节。我们最终的具体目标将是利用PTEN固有突变的考登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方面的作用。我们将在PTEN突变的人淋巴细胞中检测有丝分裂检查点的活性。我们将描述PTEN突变体的功能增益，并确定这些显性阴性PTEN突变体是否会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。这个项目的成功完成将定义PTEN作为纺锤体检查点的控制器和基因组的守护者。该项目的新发现可能为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提供见解。公共卫生相关性：PTEN缺乏和肿瘤发展叙述PTEN肿瘤抑制因子在各种人类癌症中经常发生突变。在小鼠模型中，PTEN的缺失导致肿瘤发生。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。本项目将通过揭示核PTEN在纺锤体组装和染色体分离中的关键作用，探索其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缺乏如何损害有丝分裂监视机制，导致肿瘤发展的基本问题。pten -有丝分裂途径的鉴定可能对肿瘤发生治疗策略的发展具有深远的意义。