MUTANT P53 GAIN OF FUNCTION IN TUMORIGENESIS

P53抑癌基因是人类最常发生突变的基因 人类癌症和表达突变型p53的肿瘤可能与 比p53基因缺失的癌症预后更差。这样做的长期目标是 研究建议是为了加深我们对生物信息素功能的理解 突变型p53在肿瘤发生中的作用 突变型P53增强P53阴性细胞的致瘤潜能 线条，这种活动与它选择性地 反式激活人类多药耐药(MDR1)启动子。在我们的 在之前的资金周期中，我们发现：1)突变型P53可以调节 内源性mdr1基因和内源性c-myc基因的表达 2)c-myc启动子的突变型p53反式激活 位于转录起始点下游的序列；3) C-myc基因中的突变型p53反应元件不是增强子， 具有位置和方向依赖功能；以及4)突变型P53 反式激活需要C-末端结构域，它结合RNA和 单链(Ss)DNA。这些结果导致了一个可检验的假说 突变型P53通过依赖RNA发挥反式激活作用 可能与为监管建议的模型类似的机制 TAT对人类免疫缺陷病毒LTR启动子的影响 超激活剂。 为了继续我们对突变型p53在肿瘤发生中的功能获得的研究， 我们建议解决以下具体问题：1)突变 P53促进体内肿瘤的发生；2)C-蛋白的作用是什么 突变型p53在功能获得中的末端；3)突变型P53的性质是什么 C-myc和mdr1启动子中的突变型p53反应元件；以及4) 突变型P53通过RNA在反式激活和致瘤中的作用 依赖机制？我们的发现显示出显著的差异 在野生型和突变型p53功能的结构要求中， 这可能为开发治疗药物提供可开发的基础 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的表达增强了细胞的生长和致瘤性。

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.