Oncogenic Function of a P53-Induced Phosphatase

P53 诱导磷酸酶的致癌功能

• 批准号: 6889650
• 负责人: Lawrence A. Donehower
• 金额: $ 30.06万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6889650
• 关键词: HeLa cells; SDS polyacrylamide gel electrophoresis; autoradiography; biological signal transduction; carcinogenesis; enzyme induction /repression; gene expression; genetically modified animals; immunoprecipitation; laboratory mouse; nucleic acid probes; oncogenes; p53 gene /protein; phosphomonoesterases; polymerase chain reaction; protein structure function; site directed mutagenesis; terminal nick end labeling; tissue /cell culture

DESCRIPTION (provided by applicant): The tumor suppressor p53 is structurally or functionally inactivated in most human tumors. In those tumors that retain intact p53, p53 signaling is often inactivated through altered expression of other molecules. An example of this p53 functional inactivation occurs in a fraction of human sarcomas, in which amplification and overexpression of the oncogene mdm2 results in p53 degradation. Two recent reports in the literature implicate another potential oncogene that may inactivate p53 in human breast and prostate cancers. This gene, encoding the wildtype p53-induced phosphatase wip1 or Ppm1 d). is amplified and overexpressed in 16% of human breast cancers. It is the only consistently amplified gene in these breast cancers that shows transforming activity in in vitro transformation assays. Wipl is induced by p53 following ionizing or ultraviolet radiation and it has been shown to dephosphorylate p38 MAP kinase, inactivating it and inhibiting p38 activation of p53 through phosphorylation. It is hypothesized that Wipl forms part of a negative regulatory feedback loop that indirectly inhibits p53 function following initial activation of p53. Thus, amplification of Wipl in human tumors could cause increased inhibition of p53 signaling and promote tumorigenesis through p53-dependent mechanisms. A major goal of this proposal is to use in vitro culture systems and animal models (including a Wipl knockout mouse that our laboratory has generated) to test the oncogenicib, of Wip1 in multiple contexts. We will determine whether the absence of Wipl confers a tumor resistance phenotype through increased p53 activity. We will also examine whether Wipl has p53-independent effects in enhancement of transformation or tumorigenesis and which domains of Wipl are crucial for transformation-related effects. A second major goal of this proposal is to identify normal cell signaling pathways influenced by Wipl in an attempt to understand the normal biological functions of this phosphatase. Wip1-interacting proteins will be identified and their relationship to Wipl will be explored. Our overall goal is to better understand the molecular mechanisms by which this putative human oncogene affects both normal and oncogenic cell signaling.

描述（由申请人提供）：在大多数人类肿瘤中，肿瘤抑制p53在结构或功能上都是灭活的。在保留完整p53的肿瘤中，p53信号通常通过改变其他分子的表达而被灭活。该p53功能失活的一个例子发生在人类肉瘤的一部分中，其中癌基因MDM2的扩增和过表达导致p53降解。文献中最近的两份报道暗示了另一种潜在的癌基因，可能会使人类乳房和前列腺癌中的p53失活。该基因编码WildType P53诱导的磷酸酶WIP1或PPM1 D）。在16％的人乳腺癌中被放大和过表达。它是这些乳腺癌中唯一一贯放大的基因，它显示了体外转化分析中的活性。电离或紫外线辐射后，p53诱导了WIPL，已证明它可以去磷酸化p38 MAP激酶，使其失活并抑制p38通过磷酸化激活p53。假设WIPL构成了负调节反馈回路的一部分，该反馈回路是间接抑制p53 p53后p53功能的一部分。因此，人类肿瘤中WIPL的扩增可能导致p53信号传导的抑制增加，并通过p53依赖性机制促进肿瘤发生。该提案的主要目的是在多种情况下使用体外培养系统和动物模型（包括我们实验室已经产生的WIPL敲除小鼠）来测试WIP1的致癌剂。我们将确定缺乏WIPL是否通过增加的p53活性来赋予肿瘤耐药性表型。我们还将检查WIPL在增强转化或肿瘤发生的增强中是否具有p53独立的作用，以及哪些WIPL领域对于与转化相关的效应至关重要。该提案的第二个主要目标是确定受WIPL影响的正常细胞信号通路，以了解该磷酸酶的正常生物学功能。将确定WIP1相互作用的蛋白质，并将探索它们与WIPL的关系。我们的总体目标是更好地了解这种假定的人类癌基因会影响正常和致癌细胞信号传导的分子机制。