MUTANT P53 GAIN OF FUNCTION IN TUMORIGENESIS

突变 P53 在肿瘤发生中的功能获得

• 批准号: 2615991
• 负责人: GERARD PAUL ZAMBETTI
• 金额: $ 22.86万
• 依托单位: ST. JUDE CHILDREN'S RESEARCH HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-04-01 至 2003-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2615991
• 关键词: athymic mouse; carcinogenesis; cell line; gel mobility shift assay; gene expression; gene mutation; genetic mapping; genetic promoter element; genetic transcription; human genetic material tag; multidrug resistance; neoplastic transformation; nucleic acid sequence; polymerase chain reaction; protein structure function; tissue /cell culture; transfection; tumor suppressor genes; tumor suppressor proteins

The p53 tumor suppressor gene is the most frequently mutated gene in human cancer and tumors that express mutant p53 may be associated with a worse prognosis than p53-null cancers. The long-term goal of this research proposal is to further our understanding of the function of mutant p53 in tumorigenesis. Mutant p53 enhances the tumorigenic potential of p53-negative cell lines and this activity correlates with its ability to selectively transactivate the human multi-drug resistance (MDR1) promoter. In our previous funding period, we established that: 1) mutant p53 can regulate expression of the endogenous MDR1 gene as well as the endogenous c-myc gene; 2) mutant p53 transactivation of the c-myc promoter is mediated by sequences located downstream from the transcription start site; 3) the mutant p53 response element in the c-myc gene is not an enhancer and exhibits position and orientation dependent function; and 4) mutant p53 transactivation requires the C-terminal domain, which binds RNA and single-strand (ss) DNA. These results lead to a testable hypothesis that mutant p53 functions in transactivaion through an RNA-dependent mechanism that may be similar to the model proposed for the regulation of the human immunodeficiency virus LTR promoter by the TAT transactivator. To continue our studies on mutant p53 gain of function in tumorigenesis, we propose to address the following specific questions: 1) Does mutant p53 accelerate tumorigenesis in vivo; 2) What is the role of the C- terminus of mutant p53 in gain of function; 3) What is the nature of the mutant p53 response element in the c-myc and MDR1 promoters; and 4) Does mutant p53 function in transactivation and tumorigenicity through an RNA dependent mechanism? Our findings demonstrate significant differences in the structural requirements for wild-type and mutant p53 function, which may provide an exploitable basis for developing therapeutic approaches to treating cancer. The studies proposed here will build on these observations and contribute to our understanding of how mutation of p53 enhances cell growth and tumorigenicity.

p53抑癌基因是最常见的突变基因 表达突变型 p53 的人类癌症和肿瘤可能与 比 p53 缺失的癌症预后更差。 本次活动的长远目标 研究计划是为了进一步我们对功能的理解 肿瘤发生中的突变p53。 p53突变体增强p53阴性细胞的致瘤潜力 线和这种活动与其选择性的能力相关 反式激活人类多重耐药性 (MDR1) 启动子。 在我们的 在之前的资助期间，我们确定：1）突变体 p53 可以调节 内源性 MDR1 基因以及内源性 c-myc 的表达 基因; 2) 介导c-myc启动子的突变p53反式激活 通过位于转录起始位点下游的序列； 3） c-myc 基因中的突变 p53 反应元件不是增强子，并且 表现出位置和方向相关的功能； 4) 突变型 p53 反式激活需要 C 末端结构域，该结构域结合 RNA 和 单链（ss）DNA。 这些结果得出了一个可检验的假设 突变体 p53 通过 RNA 依赖性反式激活发挥作用 机制可能类似于为监管提议的模型 TAT对人类免疫缺陷病毒LTR启动子的影响 反式激活剂。 为了继续研究突变型 p53 在肿瘤发生中的功能获得， 我们建议解决以下具体问题：1）突变是否 p53 加速体内肿瘤发生； 2）C的作用是什么？ 突变体 p53 的末端获得功能； 3) 其本质是什么 c-myc 和 MDR1 启动子中的突变 p53 反应元件； 4) 是否 突变型 p53 通过 RNA 发挥反式激活和致瘤性功能 依赖机制？ 我们的研究结果表明存在显着差异 在野生型和突变型 p53 功能的结构要求中， 这可能为开发治疗提供可利用的基础 治疗癌症的方法。 这里提出的研究将建立在 这些观察结果有助于我们理解突变是如何发生的 p53 增强细胞生长和致瘤性。