The role of cyclin E deregulation in breast tumorigenesis

描述（由申请人提供）：乳腺癌是美国女性第二常见的恶性肿瘤，对其发病机制的更深入了解应该能够开发出改进的检测、预后确定和治疗工具。细胞周期调节蛋白细胞周期蛋白 E 的过度表达经常在人类乳腺肿瘤中观察到，高细胞周期蛋白 E 被认为是癌症预后不良的标志。细胞周期蛋白 E 的失调是否直接导致乳腺肿瘤发生尚不清楚。拟议实验的总体目标是了解细胞周期蛋白 E 活性失调在乳腺肿瘤发生过程中如何发挥作用，并确定针对细胞周期蛋白 E 相关乳腺癌的关键细胞屏障。 除了细胞周期蛋白 E 高表达之外，细胞周期蛋白依赖性激酶抑制剂 p27Kip1 表达的减少也被发现与乳腺癌的不良预后相关。使用三维乳腺上皮培养物，我发现细胞周期蛋白 E 过度表达与 p27 表达减少协同作用，在体外产生过度增殖的乳腺上皮结构。在具体目标1中，我将阐述这次合作的基础。我最近开发了一种敲入小鼠，其两个主要细胞周期蛋白 E 磷酸化位点含有突变，调节其与 Fbw7/SCF 泛素连接酶复合物的结合。这些动物的组织（包括乳腺上皮）的细胞周期蛋白 E 蛋白水平和激酶活性显着升高，并且过度增殖。根据我的初步研究结果，我假设 p27 和 p53 肿瘤抑制因子抑制失调的细胞周期蛋白 E 的致癌性。在目标 2 和 3 提出的实验中，我将开发新的动物模型来了解正常 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富有成效的、独立的研究生涯，重点是了解乳腺癌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成立了我的实验室，并担任医学系血液学/肿瘤学部的助理教授。在西北大学，有一个全面的指导计划来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.