The role of Cyclin E in growth control and tumorogenesis

描述（由申请人提供）：细胞周期蛋白E是细胞周期蛋白依赖性激酶2（Cdk 2）的激活剂，是增殖哺乳动物细胞中G1-S期转变的正激活剂，因此在发育和组织补充过程中发挥重要作用。然而，细胞周期蛋白E在人类恶性肿瘤中经常过度表达和失调，表明过度或时机不当的细胞周期蛋白E-Cdk 2激活可促进肿瘤发生。然而，对细胞周期蛋白E在细胞或分子水平上的正常或病理功能知之甚少。该建议旨在通过各种体外和体内方法研究细胞周期蛋白E的功能。该提案的第一个目的集中在细胞周期蛋白E在促进细胞进入S期中的作用。将采用标准的分子和细胞生物学方法。我们也开始了一项蛋白质组学的策略，以确定新的蛋白质相关的S期促进功能的细胞周期蛋白E。第二个目标是利用细胞和分子生物学方法来阐明细胞周期蛋白E失调导致DNA损伤和基因组不稳定的机制，这最有可能与肿瘤发生有关。第三个目的是利用细胞周期蛋白E转基因小鼠致癌模型，在体内验证细胞周期蛋白E介导的基因组不稳定性假说。这是至关重要的，因为大多数先前的工作都是在细胞培养模型中进行的，这些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就会被解除管制。有趣的是，靶向细胞周期蛋白E进行泛素介导的蛋白水解的途径也靶向其他几种癌蛋白，强调了其对肿瘤发生的重要性。人们希望从了解这些基本的肿瘤发生机制中获得的见解将导致癌症预防和治疗的新方法。

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.