The role of cyclin E deregulation in breast tumorigenesis

描述（由申请人提供）：乳腺癌是美国妇女中第二常见的恶性肿瘤，对其发病机制的更深入了解应有助于开发用于检测、预后确定和治疗的改进工具。细胞周期调节蛋白cyclin E的过表达经常在人类乳腺肿瘤中观察到，并且高cyclin E被认为是预后不良癌症的标志物。细胞周期蛋白E的失调是否直接导致乳腺肿瘤的发生尚不清楚。拟议的实验的总体目标是了解解除调节的细胞周期蛋白E活性在乳腺肿瘤发生过程中的功能，并确定对细胞周期蛋白E相关的乳腺癌的关键细胞屏障。 除了细胞周期蛋白E的高表达外，细胞周期蛋白依赖性激酶抑制剂p27 Kip 1的表达降低也被发现与乳腺癌的不良预后相关。使用三维乳腺上皮细胞培养，我发现细胞周期蛋白E过度表达与p27表达减少合作，在体外产生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。我最近开发了一种敲入小鼠，在两个主要的细胞周期蛋白E磷酸化位点含有突变，调节其与Fbw 7/SCF泛素连接酶复合物的结合。来自这些动物的组织含有显著升高的细胞周期蛋白E蛋白水平和激酶活性，并且是过度增殖的，包括乳腺上皮。基于我的初步研究结果，我假设p27和p53肿瘤抑制因子抑制去调节的细胞周期蛋白E的致癌性。在目标2和3中提出的实验中，我将开发新的动物模型，以了解正常p27和p53功能的丧失如何分别促进细胞周期蛋白E相关的乳腺肿瘤发生。 拟议工作的总体职业发展目标是使我能够开始一个富有成效的，独立的研究生涯，重点是了解乳腺癌的分子发病机制的关键步骤。我最近在西北大学范伯格医学院开设了我的实验室，在那里我担任医学系血液学/肿瘤学系的助理教授。在西北，一个全面的指导计划是到位，以支持这项拟议的研究以及我的职业发展的目标。

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.