F box Proteins and Deregulated Proteolysis in Cancer

描述：(申请人提供)许多细胞调节剂的蛋白质分解 由称为SCF的泛素连接酶控制，因为它们由三个 主要亚基：Skp1、cull和许多E-box蛋白之一(FBP)。该衬底 SCF的特异性由不同的FBP亚基决定，这些亚基充当 底物识别因素。我们已经证明了细胞周期 抑制物p27通过F-box蛋白的泛素途径降解 Skp2.重要的是，我们和其他人已经记录了p27的不稳定 在人类淋巴瘤和上皮性癌症中，与肿瘤相关 攻击性。我们对泛素途径的兴趣将我们引向 26个人类F-box蛋白家族的鉴定和发现 这个家族中的一个成员，称为13-Trcp，调节着 原癌基因B-连环蛋白。因为它们具有调节细胞的功能 根据我们的初步结果，我们假设 F-box蛋白Skp2和B-Trcp的解除调控可能参与 人类癌症的起源。在目标1中，我们将进行免疫组织化学 癌组织中Skp2和B-Trcp表达的研究 不同的肿瘤银行。我们将集中研究乳腺癌、淋巴瘤 和结直肠癌。我们收集的肿瘤样本符合正常 组织和长期随访。此外，这两家肿瘤库还有 包含临床病理特征和信息的广泛数据库 标准分子标记。使用单变量和多变量分析，我们将 确定Skp2和B-Trcp作为人类新的预后标志物的价值 癌症。重要的是，我们将调查导致核辐射水平上升的可能原因 对这两种F-box蛋白进行体外检测，以检测其 活动。在目标2中，我们将培育并鉴定转基因小鼠。 过表达Skp2、B-Trcp或相应的显性-负性突变体。vbl.使用 通过这种方法，我们将能够调查强制表达的影响 其中乳腺和淋巴器官中的FBP。组织病理学 预计转基因动物模型中的改变将模仿这些人类肿瘤 其中Skp2和B-Trcp过表达，并将帮助我们定义致癌 人类肿瘤中发生的分子异常的潜在途径。 最后，在目标3中，我们将测试Skp2的抑制是否导致 对癌细胞的细胞抑制或细胞毒作用。这将通过以下方式实现 根据我们的结构设计的特异膜透性多肽 和生化信息。

DESCRIPTION: (provided by applicant) Proteolysis of many cellular regulators is controlled by ubiquitin ligases called SCFs since they are composed of three major subunits: Skp1, cull and one of many E-box proteins (Fbps). The substrate specificity of SCFs is determined by distinct Fbp subunits that act as substrate recognition factors. We have demonstrated that the cell cycle inhibitor p27 is degraded by the ubiquitin-pathway through the F-box protein Skp2. Importantly, destabilization of p27, which we and others have documented in human lymphomas and in epithelial cancers, correlates with tumor aggressivity. Our interest in the ubiquitin pathway lead us to the identification of a family of 26 human F-box proteins and the discovery that one member of this family, called 13-Trcp, regulates the stability of the proto-oncogene B-catenin. Because of their functions in regulating cell proliferation and given our preliminary results, we hypothesize that deregulation of the F-box proteins Skp2 and B-Trcp may participate in the genesis of human cancers. In Aim 1 we will carry out immunohistochemical studies on Skp2 and B-Trcp expression in cancer samples obtained from two different tumor banks. We will concentrate our study on breast cancer, lymphoma and colorectal cancer. Our collection of tumor samples has concordant normal tissue and long-term follow-ups. In addition, these two tumor banks have extensive databases containing information on clinico-pathological features and standard molecular markers. Using univariate and multivariate analyses, we will determine the value of Skp2 and B-Trcp as novel prognostic markers for human cancers. Importantly, we will investigate possible causes for increased levels of these two F-box proteins and perform in vitro assays to measure their activities. In Aim 2 we will then generate and characterize transgenic mice overexpressing Skp2, B-Trcp or corresponding dominant-negative mutants. Using this approach we will be able to investigate the effects of enforced expression of these Fbps in the mammary gland and lymphoid organs. Histopathological alterations expected in transgenic animal models will mimic those human tumors in which Skp2 and B-Trcp are overexpressed and will help us to define oncogenic pathways underlying the molecular abnormalities occurring in human tumors. Finally, in Aim 3 we will test whether the inhibition of Skp2 results in a cytostatic or cytotoxic effect in cancer cells. This will be achieved using specific membrane permeable peptides designed on the basis of our structural and biochemical information.