Molecular Mechanisms of GSTP1 Reactivation by Green Tea Polyphenols

绿茶多酚重新激活 GSTP1 的分子机制

基本信息

批准号：
7262072
负责人：
SANJAY GUPTA
金额：
$ 28.32万
依托单位：
CASE WESTERN RESERVE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-07-01 至 2012-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7262072
关键词：
Aberrant DNA Methylation Acetylation Adenocarcinoma Adverse effects Affect Alleles Androgens Animal Model Atrophic Attention Behavior Benign Prostatic Hypertrophy Binding Binding Proteins Biological Biological Assay Breast Cancer Etiology Cancer cell line Carcinogens Case-Control Studies Catechin Cell Culture System Cell Line Cells Cessation of life Characteristics Chemoprevention Chemopreventive Agent Chinese People Chromatin Chromatin Structure Chromatin Structure Alteration Chromosomal Breaks Chromosomal Instability Clinical Clinical Trials Colon Colorectal Cancer Complex Consumption CpG Islands DMA-methyltransferase DNA DNA Methylation DNA Methyltransferase DNA Modification Methylases DNA Repair Gene DNA-Binding Proteins Daily Data Deacetylation Deoxycytidine Detoxification Process Development Diagnosis Diet Dietary Factors Disease Disruption Dose Drug Metabolic Detoxication Enzymes Epidemiologic Studies Epigallocatechin Gallate Epigenetic Process Epithelial Cells Event Exhibits Experimental Animal Model Family Fright Future GSTP1 gene Gene Expression Gene Silencing Genes Genetic Genetic Recombination Genetic Transcription Genome Genome Stability Genomics Genus Cola Glutathione S-Transferase Green tea Growth Heterogeneity Histone Acetylation Histone Deacetylase Inhibitor Histone H3 Histones Human Hypermethylation Implant Incidence Inflammatory Infusion procedures Invasive Japanese Population LNCaP Laboratory Study Lead Lesion Localized Disease Lung Malignant Epithelial Cell Malignant Neoplasms Malignant neoplasm of lung Malignant neoplasm of prostate Mediating Messenger RNA Methyl-CpG-Binding Protein 2 Methylation Modeling Modification Molecular Mus Mutate Mutation Nail plate Neoplasm Metastasis Nude Mice Nutritional Oncogenes Oral Pathway interactions Patients Pattern Phase Plasma Play Poison Population Predisposition Prevention Preventive Principal Investigator Process Promoter Regions Prostate Prostate carcinoma Prostatic Prostatic Intraepithelial Neoplasias Prostatic Neoplasms Protein Acetylation Protein Binding Domain Protein Family Proteins Recruitment Activity Refractory Regulation Repetitive Sequence Reporting Repression Research Personnel Retrotransposon Risk Role Series Source Specificity Specimen Staging Supplementation Tail Testing Time Toxic effect Transcriptional Activation Transcriptional Regulation Transgenic Organisms Tumor Suppressor Genes Tumor Tissue United States Up-Regulation base bisulfite bone cancer cell cancer risk cancer type carcinogenesis chromatin remodeling day demethylation disorder prevention drinking drinking water driving force enzyme activity gallocatechol gene repression glutathione S-transferase pi histone acetyltransferase human disease in vivo inhibitor/antagonist interest man member men novel nutrition programs promoter prostate cancer prevention protective effect protein H(3)protein expression research study transcription factor tumor tumor growth tumor progression tumorigenesis

项目摘要

DESCRIPTION (provided by applicant): Aberrant DNA methylation and chromatin remodeling are common epigenetic changes that play critical role in gene silencing; implicated in the development and progression of prostate cancer. One such alteration is silencing of the expression of glutathione S-transferase-pi (GSTP1), a critical enzyme of carcinogen defense, through methylation of deoxycytidine residue in CpG islands in the 5'-regulating region. Loss of GSTP1 function occurs in vast majority (>70%) of prostate tumors regardless of grade or stage and appears to be characteristic of human prostate tumorigenesis. Unlikely mutated genes; epigenetically silenced genes are intact and are attractive targets for agents that could 'wake up' these dormant genes. Reactivation of such genes could be accomplished by DNA methylation and/or histone deacetylase inhibitors however; clinical utility of these inhibitors has been limited due to severe side- effects and toxicity. In recent years, green tea and its major polyphenolic constituent, epigallocatechin-3-gallate (EGCG) has received much attention as a promising chemopreventive agent for prostate cancer. This notion is supported by recent case-control study (Int. J. Cancer 108:130-5, 2004); clinical trial (Cancer Res. 66:1234-40, 2006) and our observation demonstrating that oral consumption of green tea polyphenols (GTP) at human achievable dose results in significant inhibition of prostate carcinogenesis in transgenic adenocarcinoma of the mouse prostate (TRAMP) model that mimics human disease (Proc. Nail. Acad. Sci. USA 98:10350-5, 2001). Extensive laboratory studies in cell culture systems and in limited animal models have further demonstrated that GTP afford protective effects from diverse types of carcinogens and induce phase II enzyme activity that could lead to enhanced detoxification process. More recently GTP has been shown to inhibit the activity of DNA methyltransferase (Cancer Res. 63:7563-70, 2003). Importantly, if drinking green tea can restore or compensate the loss of GSTP1 activity in the prostate and can slow down the process of prostate carcinogenesis that may have relevance for prevention and/or treatment of this disease. In the proposed studies we further our understanding of how GTP and EGCG mediate reactivation of GSTP1 gene, silenced during prostate carcinogenesis. Through a series of exploration, we will specifically investigate whether these molecular mechanism(s) are mediated through epigenetic pathways related to i) demethylation and activation of aberrantly methylated GSTP1 gene, ii) modulation in binding and expression of transcriptional repressers: methyl CpG binding domain (MBD) proteins, DNA methyltransferases (DNMTs), and histone deacetylases (HDAC) to methylated DNA iii) alteration in activity and expression of histone acetyltransferases (HAT), iv) histone modification, and v) global hypomethylation patterns. These studies will be conducted in human prostate carcinoma LNCaP and MDA PCa 2b cells, which possess hypermethylated GSTP1 CpG island alleles, devoid of GSTP1 mRNA and protein expression. This will be further validated in athymic nude mouse orthotopically implanted with prostate carcinoma cells. Completion of this proposal will establish an important role of green tea polyphenols in modulating epigenetic events and will provide a rationale to conduct prevention-based clinical trial. With the 'proof of principle' more structurally-related non- toxic compounds could be developed in future for prevention of prostate cancer in humans.

描述（由申请人提供）：异常的 DNA 甲基化和染色质重塑是常见的表观遗传变化，在基因沉默中发挥着关键作用；参与前列腺癌的发生和进展。其中一个改变是通过 5' 调节区 CpG 岛脱氧胞苷残基的甲基化来沉默谷胱甘肽 S-转移酶-pi (GSTP1)（一种致癌物防御的关键酶）的表达。绝大多数 (>70%) 前列腺肿瘤（无论级别或阶段如何）都会出现 GSTP1 功能丧失，这似乎是人类前列腺肿瘤发生的特征。不太可能发生突变的基因；表观遗传沉默的基因是完整的，并且是能够“唤醒”这些休眠基因的药物的有吸引力的目标。然而，这些基因的重新激活可以通过 DNA 甲基化和/或组蛋白脱乙酰酶抑制剂来完成。由于严重的副作用和毒性，这些抑制剂的临床应用受到限制。近年来，绿茶及其主要多酚成分表没食子儿茶素-3-没食子酸酯（EGCG）作为一种有前途的前列腺癌化学预防剂而受到广泛关注。这一观点得到了最近的病例对照研究的支持（Int. J. Cancer 108:130-5, 2004）；临床试验（Cancer Res. 66:1234-40, 2006）和我们的观察表明，口服人类可达到剂量的绿茶多酚 (GTP) 可显着抑制转基因小鼠前列腺腺癌 (TRAMP) 模型中的前列腺癌发生模仿人类疾病（Proc. Nail. Acad. Sci. USA 98:10350-5, 2001）。在细胞培养系统和有限的动物模型中进行的广泛实验室研究进一步证明，GTP 对多种类型的致癌物具有保护作用，并诱导 II 相酶活性，从而增强解毒过程。最近，GTP 已被证明可以抑制 DNA 甲基转移酶的活性（Cancer Res. 63:7563-70, 2003）。重要的是，如果喝绿茶可以恢复或补偿前列腺中 GSTP1 活性的损失，并可以减缓前列腺癌发生的过程，这可能与预防和/或治疗这种疾病有关。在拟议的研究中，我们进一步了解 GTP 和 EGCG 如何介导在前列腺癌发生期间沉默的 GSTP1 基因的重新激活。通过一系列探索，我们将具体研究这些分子机制是否通过与以下相关的表观遗传途径介导：i) 异常甲基化 GSTP1 基因的去甲基化和激活，ii) 转录抑制因子的结合和表达的调节：甲基 CpG 结合域(MBD) 蛋白、DNA 甲基转移酶 (DNMT) 和组蛋白脱乙酰酶 (HDAC) 转化为甲基化 DNA iii) 组蛋白乙酰转移酶活性和表达的改变(HAT)，iv) 组蛋白修饰，以及 v) 整体低甲基化模式。这些研究将在人前列腺癌 LNCaP 和 MDA PCa 2b 细胞中进行，这些细胞具有高度甲基化的 GSTP1 CpG 岛等位基因，缺乏 GSTP1 mRNA 和蛋白表达。这将在原位植入前列腺癌细胞的无胸腺裸鼠中得到进一步验证。该提案的完成将确立绿茶多酚在调节表观遗传事件中的重要作用，并将为开展基于预防的临床试验提供依据。通过“原理证明”，未来可以开发更多结构相关的无毒化合物来预防人类前列腺癌。