Mechanisms of cyclin E associated tumorigenesis

描述(申请人提供)：细胞周期蛋白E与其蛋白激酶CDK2共同控制细胞周期从G1期进入S期。大多数人类癌症在调节G1期到S期进展的主要途径中存在突变，这些突变解除了对细胞周期蛋白E-CDK2活性的调控。尽管细胞周期蛋白E-CDK2活性被认为是直接导致肿瘤转化的因素，但将细胞周期蛋白E与肿瘤发生联系起来的机制仍不清楚。我们研究了Cyclin E在原代细胞中解除调控的后果，意外地发现Cyclin E的过度表达启动了抑制Cyclin E-CDK2活性的动态平衡反应。当这一反应失活时，过表达的细胞周期蛋白E会导致严重的细胞周期异常和遗传不稳定性的证据。因此，这种需要p53肿瘤抑制蛋白和细胞周期蛋白依赖性激酶抑制物p21的反应，可以保护细胞免受细胞周期蛋白E去调控的影响，并可能构成一种抵抗细胞周期蛋白E相关癌症的生理屏障。 本申请中提出的实验旨在了解Cyclin E去调控的细胞后果以及Cyclin E去调控在肿瘤发生中的作用。特异性目标1的目的是阐明细胞周期蛋白E激活P53的机制。细胞周期蛋白E-CDK2活性过高会导致细胞周期缺陷的S期进展和累积性细胞遗传学异常。具体目标2的目的是了解Cyclin E活性导致基因组损伤的机制，以及P53失活是否是这一过程中的必要步骤。细胞周期蛋白E的失控和P53的丢失可能通过促进遗传损伤而使主要的细胞保护反应失活，从而协同致癌。因此，特定目标3的目标是通过建立与细胞周期蛋白E相关的小鼠癌症模型来确定细胞周期蛋白E和p53缺失在肿瘤发生过程中是否协同作用。 这项建议的职业发展目标是使首席研究员能够获得必要的技能，以发展成功和独立的研究生涯，兴趣架起细胞周期调控和肿瘤生物学之间的桥梁。这项建议由Bruce Clurman博士和James Roberts博士共同指导，他们在研究正常细胞和癌细胞的细胞周期调控方面具有丰富的经验。弗雷德·哈钦森癌症研究中心包括一个蓬勃发展的科学家和医生社区，他们在癌症生物学的不同领域拥有专业知识，因此为这项研究计划提供了理想的培训环境。

DESCRIPTION (provided by applicant): Cyclin E, with its partner kinase Cdk2, controls cell cycle progression from G1 to S phase. Most human cancers contain mutations in the major pathway that regulates G1 to S phase progression, and these mutations deregulate cyclin E-Cdk2 activity. Though deregulated cyclin E-Cdk2 activity is thought to contribute directly to neoplastic transformation, the mechanisms connecting cyclin E to tumorigenesis remain unclear. We studied the consequences of cyclin E deregulation in primary cells and unexpectedly found that cyclin E overexpression initiates a homeostatic response that restrains cyclin E-Cdk2 activity. When this response is inactivated, overexpressed cyclin E induces profound cell cycle abnormalities and evidence of genetic instability. Therefore, this response, which requires the p53 tumor suppressor protein and the cyclin dependent kinase inhibitor, p21, protects cells against cyclin E deregulation and may comprise a physiologic barrier against cyclin E associated cancer. The experiments proposed in this application seek to understand the cellular consequences of cyclin E deregulation and the contributions of cyclin E deregulation to tumorigenesis. The goal of Specific Aim 1 is to elucidate the mechanism by which cyclin E activates p53. Excess cyclin E-cdk2 activity induces defective S phase progression and accumulated cytogenetic abnormalities. The goal of Specific Aim 2 is to understand the mechanisms through which cyclin E activity causes genome damage and whether p53 inactivation is an obligatory step in this process. The combination of cyclin E deregulation and p53 loss may be synergistically oncogenic by promoting genetic damage while inactivating the major cellular protective response against this damage. The goal of Specific Aim 3 is thus to determine if cyclin E and p53 loss cooperate during tumorigenesis by developing mouse models of cyclin E associated cancers. The career development goal of this proposal is to enable the principal investigator to acquire the necessary skills to develop a successful and independent research career with interests bridging cell cycle regulation and tumor biology, This proposal is co-mentored by Drs. Bruce Clurman and James Roberts, who have extensive experience studying cell cycle regulation in normal and cancer cells. The Fred Hutchinson Cancer Research Center includes a thriving community of scientists and physicians with expertise in diverse areas of cancer biology and thus provides an ideal training environment for this research proposal.