The role of p53 in remodeling DNA methylation in cancer

p53 在重塑癌症 DNA 甲基化中的作用

• 批准号: 6760821
• 负责人: SHIRLEY M TAYLOR
• 金额: $ 26.01万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6760821
• 关键词: CpG islands; DNA methylation; RNA interference; astrocytes; carcinogenesis; cell transformation; chromatin immunoprecipitation; fibroblasts; gene expression; gene induction /repression; gene targeting; genetic promoter element; genetically modified animals; glioma; human tissue; laboratory mouse; mass spectrometry; methylguanine DNA methyltransferase; microarray technology; neoplasm /cancer genetics; neoplastic process; p53 gene /protein; small interfering RNA; tissue /cell culture; tumor suppressor genes

DESCRIPTION (provided by applicant): The pattern of methylation of genomic DNA becomes significantly altered during oncogenesis. In human tumors, the overall level of DNA-cytosine methylation is decreased, but CpG islands generally become hypermethylated, resulting in frequent epigenetic inactivation of tumor suppressor genes. One of the most common observations is that one allele of a tumor suppressor gene becomes mutated or lost, and the other allele becomes silenced by hypermethylation. Little is known of the events that trigger this aberrant de novo methylation, nor of is it known which of the three characterized DNA methyltransferases is responsible. It is however, well recognized that the methylation machinery must be under strict regulatory control during development, and that the balance of factors involved in this regulation appears to be disrupted during tumorigenesis. The tumor suppressor gene, p53 is mutated or lost in more than 50% of all types of human tumors, and appears to be an early event in tumorigenesis in many cases. We have recently found that p53 binds the DNA methyltransferase 1 (Dnmt1) promoter in the absence of stimuli that activate p53, that activation of p53 reduces this binding, and that loss of p53 function induces upregulation of Dnmt1. These data suggest that aberrant genomic methylation might be promoted by alteration or loss of this important cancer gene. We now propose to determine the underlying mechanism of p53-mediated control of DNA methyltransferase1, its generality to the related DNA methyltransferases, and its role in the loss of tumor suppressor gene function during carcinogenesis. We propose to study the interaction of wild type and mutant p53s with the promoter regions of the Dnmt loci both in vitro and in vivo, using chromatin immunoprecipitation, to modulate the levels of p53 and Dnmts using siRNA technology, and to study the composition of protein complexes involving p53 and its mutant forms resident on the promoters of the Dnmt genes using tandem mass spectrometry. These studies will lead to an understanding of the early events in tumor progression that result in disruption of the control of DNA methylation. The inappropriate tumor suppressor gene silencing that follows this loss of control appears to be critical in promoting oncogenesis.

描述（由申请人提供）：基因组DNA的甲基化模式在肿瘤发生期间发生显着改变。 在人类肿瘤中，DNA-胞嘧啶甲基化的总体水平降低，但CpG岛通常变得高度甲基化，导致肿瘤抑制基因的频繁表观遗传失活。 最常见的观察结果之一是肿瘤抑制基因的一个等位基因突变或丢失，另一个等位基因因过度甲基化而沉默。 触发这种异常从头甲基化的事件知之甚少，也不知道三种特征性DNA甲基转移酶中的哪一种负责。 然而，众所周知，甲基化机制在发育过程中必须受到严格的调控，并且参与这种调控的因子的平衡似乎在肿瘤发生期间被破坏。肿瘤抑制基因p53在超过50%的所有类型的人类肿瘤中突变或丢失，并且在许多情况下似乎是肿瘤发生的早期事件。 我们最近发现，p53结合的DNA甲基转移酶1（Dnmt 1）启动子的刺激激活p53的情况下，p53的激活减少这种结合，和p53功能的丧失诱导上调Dnmt 1。这些数据表明，异常的基因组甲基化可能是由这一重要的癌症基因的改变或丢失所促进的。 我们现在提出，以确定潜在的机制p53介导的控制DNA甲基转移酶1，其一般性相关的DNA甲基转移酶，其作用在肿瘤发生过程中的肿瘤抑制基因功能的丧失。 我们建议在体外和体内研究野生型和突变型p53与Dnmt基因座的启动子区域的相互作用，使用染色质免疫沉淀，使用siRNA技术调节p53和Dnmt的水平，并使用串联质谱研究涉及p53及其突变形式驻留在Dnmt基因启动子上的蛋白复合物的组成。 这些研究将导致对肿瘤进展中导致DNA甲基化控制中断的早期事件的理解。不适当的肿瘤抑制基因沉默，随后这种控制的损失似乎是至关重要的，在促进肿瘤发生。