The role of Cyclin E in growth control and tumorogenesis

描述(申请人提供)：细胞周期蛋白E是细胞周期蛋白依赖性激酶2(CDK2)的激活剂，是哺乳动物细胞增殖中G1-S相变的正激活剂，因此在组织的发育和补充中起着重要作用。然而，Cyclin E在人类恶性肿瘤中经常过度表达和失控，这表明过度或错误的Cyclin E-CDK2激活可以促进肿瘤的发生。然而，人们对细胞或分子水平上的细胞周期蛋白E的正常或病理功能知之甚少。这项建议试图通过各种体外和体内方法来研究细胞周期蛋白E的两种功能。该提案的第一个目的是关注细胞周期蛋白E在促进细胞进入S期的作用。将采用标准的分子和细胞生物学方法。第二个目的是利用细胞和分子生物学方法来阐明细胞周期蛋白E去调控导致DNA损伤和基因组不稳定的机制(S)，这是最有可能与肿瘤发生有关的因素。第三个目的是利用细胞周期蛋白E转基因小鼠的致癌模型来验证细胞周期蛋白E在体内介导基因组不稳定性的假说。这一点至关重要，因为大多数先前的工作都是在细胞培养模型中进行的，而细胞培养模型与人类癌症的相关性有限。最后，我们正在研究细胞周期蛋白E周转的机制，因为当这个过程失败时，细胞周期蛋白E就会被解除调控。有趣的是，以细胞周期蛋白E为靶点进行泛素介导的蛋白分解的途径也以其他几种癌蛋白为靶点，这突显了其在肿瘤发生中的重要性。人们希望，从了解这些肿瘤发生的基本机制中获得的见解将导致癌症预防和治疗的新方法。与公共健康相关：癌症是一种对美国和世界都有巨大健康影响的疾病。然而，在治愈大多数类型的癌症方面只取得了有限的进展。在一定程度上，这是因为许多关于癌症基本生物学的机械问题仍然没有得到回答。这项提议试图解决其中一些悬而未决的问题。

DESCRIPTION (provided by applicant): Cyclin E, an activator of cyclin-dependent kinase 2 (Cdk2) is a positive activator of the G1-S phase transition in proliferating mammalian cells and therefore serves an important function during development and in replenishment of tissues. However, cyclin E is frequently overexpressed and deregulated in human malignancies, indicating that excessive or mistimed cyclin E-Cdk2 activation can promote oncogenesis. Yet little is known about the normal or pathological functions of cyclin E at the cellular or molecular level. This proposal seeks to investigate both functions of cyclin E through a variety of in vitro and in vivo approaches. The first aim of the proposal focuses on the roles of cyclin E in promoting entry of cells into S phase. Standard molecular and cell biological approaches will be employed. We have also embarked on a proteomic strategy to identify new proteins relevant to the S- phase promoting function of cyclin E. The second aim utilizes cell and molecular biological approaches to elucidate the mechanism(s) whereby cyclin E deregulation causes DNA damage and genomic instability, the most likely link to oncogenesis. In the third aim, cyclin E transgenic mouse carcinogenesis models are used to test the hypothesis of cyclin E- mediated genomic instability in vivo. This is critical, as most prior work has been carried out in cell culture models, which have only a limited relevance to human cancer. Finally, we are investigating the mechanism of cyclin E turnover, since cyclin E becomes deregulated when this process fails. Interestingly, the pathway that targets cyclin E for ubiquitin-mediated proteolysis also targets several other oncoproteins, underscoring its importance for oncogenesis. It is hoped that insights gained from understanding these fundamental mechanisms of oncogenesis will lead to new approaches to cancer prevention and therapy. PUBLIC HEALTH RELEVANCE: Cancer is a disease with tremendous health implications for the US and world. Yet, only limited progress has been made in curing most types of cancer. In part, this is because many mechanistic questions concerning the basic biology of cancer remain unanswered. This proposal seeks to address some of these unanswered questions.