EXPRESSION OF CELL CYCLE PROTEINS IN BREAST CANCER

描述：(改编自研究人员的摘要)细胞周期依赖 激酶(CDK)形成一个协调细胞分裂的酶家族 周而复始。CDK的周期性激活需要它们与 一种叫做细胞周期蛋白的蛋白质，以及它们与抑制亚基的解离， 叫Ckis。泛素-蛋白酶体介导的蛋白降解是一种主要机制 细胞周期调节器的蛋白质水平受其调控 对促有丝分裂和反有丝分裂刺激的反应。他们之前已经 显示在正常二倍体细胞中，CKI p27的蛋白水平主要是 通过泛素-蛋白酶体系统的降解来调节。同样， 其他G1调节蛋白(Cyclin E、Cyclin D1、E2F-1)的降解是 受泛素途径控制。正向细胞周期过度激活 调节剂(例如，周期蛋白、E2F-1、CDC25)和CKI的失活(例如， P27、p16)在肿瘤发生中起重要作用。这些变化处于不活动状态 可以通过突变或转录沉默的方式发生 相应的基因，或通过改变蛋白质的稳定性。的确， 虽然p27基因从未在人类肿瘤中被发现改变，但它们已经 最近观察到，侵袭性的人类结直肠癌已经减少 P27的表达和p27特异性蛋白水解酶活性的增强。 以确定细胞周期调节因子的异常表达 代表了人类乳腺癌的新预后标志物，他们将使用 免疫组织化学和原位杂交法分析血管内皮细胞的表达 细胞周期调节因子(p27、Cyclin D1、Cyclin E、E2F-1和CDC25 B)和 他们在大约600个人乳房的档案切片中的mRNA 癌症(特定目标1)。这些肿瘤样本，从三个 不同的肿瘤库，拥有协调的正常组织和长期的 后续行动。此外，每个肿瘤银行都有一个广泛的数据库 包含有关临床病理特征和标准的信息 分子标记，使它们能够确定细胞的预后价值 周期调节器。他们将把研究重点放在1厘米长的乳腺癌上。 大小，以及来自绝经前妇女的肿瘤。 他们假设侵袭性肿瘤促进了p27和p27的降解 其他细胞周期抑制物与细胞周期降解减少 激活剂，从而获得明显的增长优势。来测试一下 细胞周期调节蛋白的非调控蛋白降解是 它们在乳腺癌中的异常表达，他们将分析肿瘤 乳房样本中特定降解活动的丰度和 细胞内各种泛素结合酶(UBC)的水平 周期调节(具体目标2)。

DESCRIPTION: (adapted from the investigator's abstract) Cyclin-dependent kinases (Cdks) form a family of enzymes that coordinate the cell division cycle. The periodic activation of cdks requires their association with proteins called cyclins, and their dissociation from inhibitory subunits, called Ckis. Ubiquitin-proteasome-mediated proteolysis is a major mechanism by which the protein levels of cell cycle regulators are regulated in response to mitogenic and anti-mitogenic stimuli. They have previously shown that in normal diploid cells protein levels of the cki p27 are mainly regulated by degradation via the ubiquitin-proteasome system. Similarly, degradation of other G1 regulatory proteins (Cyclin E, Cyclin D1, E2F-1) is controlled by the ubiquitin-pathway. Over-activation of positive cell cycle regulators (e.g., cyclins, E2F-1, Cdc25) and inactivation of Ckis (e.g., p27, p16) play a significant role in oncogenesis. These changes inactivity can occur through mutation, or transcriptional silencing of the corresponding gene, or through changes in protein stability. Indeed, although p27 gene has never been found altered in human tumors, they have recently observed that aggressive human colorectal carcinomas have reduced expression of p27 and enhanced proteolytic activity specific for p27. To determine whether the abnormal expression of cell cycle regulators represents novel prognostic markers for human breast cancer, they will use immunohistochemistry and in situ hybridization to analyze the expression of cell cycle regulators (p27, Cyclin D1, Cyclin E, E2F-1, and Cdc25 B) and their mRNA in archival sections from approximately six hundred human breast cancers (Specific Aim 1). These tumor samples, obtained from three different tumor banks, have concordant normal tissues and a long term follow-up. Furthermore, each tumor bank has an extensive data base containing information on clinico-pathological features and standard molecular markers, allowing them to determine the prognostic value of cell cycle regulators. They will focus the study on breast carcinomas 1 cm in size, and tumors obtained from pre-menopausal women. They hypothesize that aggressive tumors have enhanced degradation of p27 and other cell cycle inhibitors and decreased degradation of cell cycle activators, thus acquiring a distinct growth advantage. To test whether deregulated proteolysis of cell cycle regulatory proteins is responsible for their abnormal expression in breast carcinomas, they will analyze tumor breast samples for the abundance of specific degradation activities and for the levels of various ubiquitin conjugating enzymes (Ubcs) involved in cell cycle regulation (Specific Aim 2).