Targeting Cell Cycle Machinery in Breast Cancer

该提案的总体目标是测试靶向单个细胞周期蛋白是否代表不同类型人类乳腺癌的高度选择性治疗策略。哺乳动物细胞的增殖是由细胞核中的核心细胞周期机制驱动的。这种机制的关键组成部分是称为细胞周期蛋白的蛋白质，其结合、激活并为其相关的细胞周期蛋白依赖性激酶（CDK）提供底物特异性。这些细胞周期蛋白-CDK复合物磷酸化细胞蛋白，从而驱动细胞增殖。 小鼠基因敲除实验表明，个别细胞周期蛋白和CDK的发育和大多数细胞类型的正常增殖。相反，这些蛋白质对于特定癌症类型的启动和维持是必不可少的，这取决于它们携带的遗传病变。与此应用相关，我们的实验室最近证明，在携带MMTV-Erb 82（HER 2）驱动的乳腺癌的小鼠中，细胞周期蛋白01的普遍、全局关闭阻断了肿瘤细胞增殖并触发了肿瘤细胞衰老，而对动物的生理学没有任何明显的影响。重要的是，向荷瘤动物施用CDK 4和CDK 6的抑制剂（PD 0332991）具有相同的效果，即其引起Erb 82驱动的乳腺癌细胞的衰老。这些观察结果表明，抑制CDK 4/6激酶活性可能是HER 2阳性（HER 2+）乳腺癌女性的一种非常有效的治疗策略。 在目标1中提出的工作中，我们将把我们的分析扩展到人类HER 2+乳腺癌。我们将利用Polyak博士收集的大量人类乳腺癌细胞系（包括几种HER 2+）。我们还将使用原发性HER 2+乳腺癌的异种移植物来测试CDK 4/6抑制对人乳腺癌的影响。最后，我们将阐明人HER 2+乳腺癌细胞如何对CDK 4/6抑制产生抗性。在目标2中，我们将把我们的方法扩展到三阴性乳腺癌，在那里几乎没有治疗选择。我们将测试我们的假设，这种特定的癌症类型依赖于细胞周期蛋白E-CDK 1和/或A-CDK 1激酶。具体目标是：目标1。确定人Erb 82阳性（HER 2+）乳腺癌对细胞周期蛋白D-CDK 4/6抑制的反应;目的2.研究三阴性乳腺癌对CDK 1功能的需求

The overall goal of this proposal is to test whether targeting individual cell cycle proteins represents a highly selective therapeutic strategy in different types of human breast cancer. The proliferation of mammalian cells is driven by the core cell cycle machinery operating in cell nucleus. The key components of this machinery are proteins called cyclins, which bind, activate and provide substrate specificity to their associated cyclin-dependent kinases (CDKs). These cyclin-CDK complexes phosphorylate cellular proteins, thereby driving cell proliferation. Mouse gene knockout experiments demonstrated that individual cyclins and CDKs are dispensable for development and for normal proliferation of the majority of cell types. In contrast, these proteins are essential for the initiation and for maintenance of specific cancer types, depending on the genetic lesion they carry. Relevant for this application, our laboratory recently demonstrated that an ubiquitous, global shutdown of cyclin 01 in mice bearing MMTV-Erb82 (HER2) driven breast cancers blocked tumor cell proliferation and triggered tumor cell senescence, without having any obvious impact on animals' physiology. Importantly, administration of an inhibitor of CDK4 and CDK6 (PD 0332991) to tumor bearing animals had the same effect, namely it caused senescence of Erb82-driven breast cancer cells. These observations suggest that inhibition of CDK4/6 kinase activity may represent a very effective therapeutic strategy in women with HER2-positive (HER2+) breast cancers. In the work proposed in Aim 1, we will extend our analyses to human HER2+ breast cancers. We will take advantage of a very large collection of human breast cancer cell lines (including several HER2+) assembled by Dr. Polyak. We will also use xenografts of primary HER2+ breast cancers, to test the effect of CDK4/6 inhibition on human mammary carcinomas. Lastly, we will elucidate how human HER2+ breast cancer cells develop resistance to CDK4/6 inhibition. In Aim 2, we will extend our approach to triple-negative breast cancers, where very few therapeutic options are available. We will test our hypothesis that this specific cancer type depends of cyclin E-CDK1 and/or A-CDK1 kinase. The Specific Aims are: Aim 1. To determine the response of human Erb82-positive (HER2+) breast cancers to cyclin D-CDK4/6 inhibition; Aim 2. To study the requirement for CDK1 function in triple-negative breast cancers