The role of cyclin E deregulation in breast tumorigenesis

描述(申请人提供)：乳腺癌是美国女性中第二常见的恶性肿瘤，对其发病机制的更透彻的了解将有助于开发改进的检测、预后确定和治疗工具。细胞周期调节蛋白Cyclin E在人类乳腺肿瘤中经常被观察到过度表达，高Cyclin E被认为是预后不良的癌症的标志。目前尚不清楚细胞周期蛋白E的失控是否直接导致了乳腺肿瘤的发生。拟议实验的总体目标是了解解除调控的细胞周期蛋白E活性如何在乳腺肿瘤发生过程中发挥作用，并确定对抗细胞周期蛋白E相关乳腺癌的关键细胞屏障。 除了细胞周期蛋白E的高表达外，细胞周期蛋白依赖的激酶抑制因子p27Kip1的低表达也被发现与乳腺癌的不良预后有关。利用三维乳腺上皮细胞培养，我发现在体外，细胞周期蛋白E的过度表达和p27的低表达协同作用，产生了过度增殖的乳腺上皮结构。在具体目标1中，我将阐明这种合作的基础。我最近开发了一只敲门小鼠，该小鼠包含两个主要的细胞周期蛋白E磷酸化位点突变，调节其与Fbw7/SCF泛素连接酶复合体的结合。这些动物的组织含有明显升高的细胞周期蛋白E水平和激酶活性，并且是高度增殖的，包括乳腺上皮。根据我的初步研究结果，我假设p27和p53肿瘤抑制物抑制了未受调控的细胞周期蛋白E的致瘤性。在AIMS 2和3中提出的实验中，我将建立新的动物模型，以了解正常的p27和p53功能的丧失如何促进细胞周期蛋白E相关的乳腺肿瘤的发生。 这项拟议工作的总体职业发展目标是使我能够开始一份富有成效的独立研究生涯，专注于了解乳腺癌分子发病机制中的关键步骤。我最近在西北大学范伯格医学院开始了我的实验室，在那里我加入了血液学/肿瘤学分部医学系的助理教授。在西北大学，一个全面的指导计划已经到位，以支持这项拟议研究的目标以及我的职业发展。

DESCRIPTION (provided by applicant): Breast cancer is the second most frequently occurring malignancy in U.S. women, and a more thorough understanding of its pathogenesis should enable the development of improved tools for detection, prognosis determination, and treatment. Overexpression of the cell cycle regulatory protein, cyclin E, is frequently observed in human breast tumors, and high cyclin E is proposed to be a marker of poor prognosis cancers. Whether deregulation of cyclin E contributes directly to breast tumorigenesis is unknown. The overall goals of the proposed experiments are to understand how deregulated cyclin E activity functions during mammary tumorigenesis and to identify the key cellular barriers against cyclin E-associated breast cancer. In addition to high cyclin E expression, reduced expression of the cyclin-dependent kinase inhibitor p27Kip1 has also been found to correlate with poor prognosis in breast cancers. Using three-dimensional mammary epithelial cultures, I found that cyclin E overexpression cooperates with decreased p27 expression to produce hyper-proliferative mammary epithelial structures in vitro. In Specific Aim 1, I will elucidate the basis for this cooperation. I recently developed a knockin mouse containing mutations at two major cyclin E phosphorylation sites regulating its binding to Fbw7/SCF ubiquitin ligase complex. Tissues from these animals contain markedly elevated cyclin E protein levels and kinase activity and are hyper-proliferative, including the mammary epithelia. Based on results of my preliminary studies, I hypothesize that the p27 and p53 tumor suppressors inhibit the oncogenicity of deregulated cyclin E. In experiments proposed in Aims 2 and 3, I will develop new animal models to understand how loss of normal p27 and p53 function, respectively, promotes cyclin E-associated mammary tumorigenesis. The overall career development goal of the proposed work is to enable me to begin a productive, independent research career focused on understanding critical steps in the molecular pathogenesis of breast cancer. I recently started my laboratory at the Northwestern University Feinberg School of Medicine, where I joined as Assistant Professor in the Department of Medicine, Hematology/Oncology Division. At Northwestern, a comprehensive mentoring program is in place to support the goals of this proposed research as well as my career development.