Reactivation Methylation-Silenced Genes by Polyphenols

通过多酚重新激活甲基化沉默的基因

• 批准号: 7064300
• 负责人: CHUNG S. YANG
• 金额: $ 27.98万
• 依托单位: RUTGERS, THE STATE UNIV OF N.J.
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-10 至 2008-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7064300
• 关键词: CpG islands; DNA methylation; angiogenesis inhibitors; antineoplastics; butyrates; colon neoplasms; dietary supplements; flavonoids; gene induction /repression; genetic transcription; genetically modified animals; laboratory mouse; methyltransferase; microarray technology; molecular oncology; neoplasm /cancer nutrition therapy; neoplastic cell; nutrition aspect of cancer; nutrition related tag; oral pharyngeal neoplasm; polymerase chain reaction; prostate neoplasms; protein structure function; tea; tissue /cell culture

DESCRIPTION (provided by applicant): Hypermethylation of promoter CpG islands is an important mechanism to silence the expression of many tumor suppressors, DNA repair, and other genes in cancer. The long-term goal of this project is to study the inhibition and reversal of this process by dietary polyphenols for the purpose of prevention and treatment of cancer. In preliminary studies, we observed that treatment of human esophageal cancer KYSE 510 cells with the tea polyphenol EGCG caused the reversal of hypermethylation of RARbeta, p16, MGMT, and hMLH1 and the regaining of gene expression. EGCG also inhibited DNMT activity in nuclear extracts. This property of EGCG and related compounds could be explored for cancer chemoprevention and therapy. Our hypothesis is that EGCG and some other dietary polyphenols can inhibit DNMT, prevent or reverse the gene silencing caused by hypermethylation, and contribute to the inhibition of carcinogenesis, In this proposal, we plan to test this hypothesis with the following Specific Aims: 1. To quantify the demethylation and reactivation of hypermethylation-silenced genes (MSGs) such as RARbeta, p16, MGMT, and hMLH1 by EGCG, characterize the pattern of CpG demethylation, and determine the sustainability of the reactivated gene expression. 2. To elucidate the mechanisms by which EGCG inhibits DNMT activity and DNA hypermethylation. The leading hypothesis is that inhibition of DNMT1 by EGCG causes demethylation. Other mechanisms such as those involving AdoMet levels and other methyltransferases, will also be examined. 3. To establish the above observed effects as general phenomena by determining the spectrum of MSGs that are reactivated by EGCG (using methylation microarrays), examining the effects of EGCG on other cell lines (oral, colon, and prostate cancers), and investigating the effects of other dietary polyphenols. 4. To determine the possible synergistic effects in the reactivation of MSGs when EGCG is used in combination with a HDAC inhibitor (butyrate or TSA) or retinoic acid. Possible effects on global hypomethylation will be analyzed. 5. To determine whether EGCG, alone or in combination with other agents, can prevent hypermethylation of genes and tumor development in the intestinal tumorigenesis model in the Min mice.

描述（由申请人提供）： 启动子 CpG 岛的高甲基化是沉默许多肿瘤抑制因子、DNA 修复和癌症中其他基因表达的重要机制。该项目的长期目标是研究膳食多酚对这一过程的抑制和逆转，以达到预防和治疗癌症的目的。在初步研究中，我们观察到用茶多酚 EGCG 处理人食管癌 KYSE 510 细胞可逆转 RARbeta、p16、MGMT 和 hMLH1 的高甲基化并恢复基因表达。 EGCG 还抑制核提取物中的 DNMT 活性。 EGCG 和相关化合物的这一特性可用于癌症的化学预防和治疗。我们的假设是，EGCG和其他一些膳食多酚可以抑制DNMT，预防或逆转由高甲基化引起的基因沉默，并有助于抑制致癌作用。在本提案中，我们计划通过以下具体目标来检验这一假设： 1. 通过 EGCG 定量 RARbeta、p16、MGMT 和 hMLH1 等高​​甲基化沉默基因 (MSG) 的去甲基化和重新激活，表征 CpG 去甲基化模式，并确定重新激活基因表达的可持续性。 2. 阐明EGCG抑制DNMT活性和DNA高甲基化的机制。主要假设是 EGCG 抑制 DNMT1 会导致去甲基化。其他机制，例如涉及 AdoMet 水平和其他甲基转移酶的机制，也将受到检查。 3. 通过确定 EGCG 重新激活的 MSG 谱（使用甲基化微阵列），检查 EGCG 对其他细胞系（口腔癌、结肠癌和前列腺癌）的影响，并研究其他膳食多酚的影响。 4. 确定当 EGCG 与 HDAC 抑制剂（丁酸盐或 TSA）或视黄酸联合使用时，味精重新激活中可能的协同效应。将分析对全球低甲基化的可能影响。 5. 确定EGCG单独或与其他药物联合使用是否可以预防Min小鼠肠道肿瘤发生模型中基因的高甲基化和肿瘤的发展。