Roles of polymorphic COMT, tea polyphenols and proteasome in cancer prevention

多态COMT、茶多酚和蛋白酶体在癌症预防中的作用

基本信息

批准号：
7221981
负责人：
QING PING DOU
金额：
$ 23.35万
依托单位：
WAYNE STATE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2006
资助国家：
美国
起止时间：
2006-04-12 至 2011-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7221981
关键词：
Acquired Immunodeficiency Syndrome Address Affinity Alleles Animals Antineoplastic Agents Apoptosis Apoptotic Beverages Binding Biological Biological Availability Biological Process Boronic Acids Breast Cancer Cell Caspase Catechol O-Methyltransferase Catechols Caucasians Caucasoid Race Cell Cycle Cell Death Cell Extracts Cells Cessation of life Clinical Computer Simulation Consumption Cultured Cells Data Disease Doctor of Philosophy Endopeptidases Epidemiologic Studies Epigallocatechin Gallate Esters Future General Population Genotype Glycol Green tea Homologous Gene Human Hydrolysis Intervention Malignant Neoplasms Mammary Neoplasms Mediating Metabolic Biotransformation Methylation Methyltransferase Gene Modeling Molecular Molecular Target Multiple Myeloma Mutate Normal Cell Nude Mice Numbers Object Attachment Oncogenes Organism Pathway interactions Patients Peptide Hydrolases Peptides Phase I/II Trial Phase III Clinical Trials Population Process Property Proteasome Inhibitor Proteins Range Reaction Reporting Research Research Personnel Resistance Risk Role Series Stimulus Structure Study Section Tea Testing Trypsin Ubiquitin United States United States Food and Drug Administration Woman Xenograft procedure analog base boronic acid cancer cell cancer prevention cell suicide chymotrypsin design gallocatechol genetic regulatory protein in vivo inhibitor/antagonist malignant breast neoplasm multicatalytic endopeptidase complex neoplastic cell novel polyphenol prevention clinical trial programs tumor xenograft

项目摘要

DESCRIPTION (provided by applicant): Research has supported proteasome inhibitors as potential novel anticancer drugs and green tea polyphenols (GTPs) as a cancer-preventative agent. We have reported that GTPs, e.g. (-)-epigallocatechin- 3-gallate or EGCG, are potent and specific inhibitors of proteasomal chymotrypsin-like activity (mediated by b5 subunit). Methylation of GTPs, a major biotransformation reaction limiting their cancer-preventative activities in vivo, is mediated by human polymorphic catechol-O-methyltransferase (COMT). The point- mutated COMT, found in -25% of US population, has 3-4-fold decreased enzymatic activity (COMT-LL). It was reported that women tea-drinkers with at least one low activity COMT allele (but not COMT-HH) showed a significantly reduced risk of breast cancer compared with non-tea drinkers, suggesting less protection by methylated polyphenols. To study the responsible mechanism, we hypothesize that O-methylation of GTPs by COMT in breast cancer cells decreases their proteasome-inhibitory and consequently biological activities. This hypothesis is supported by our preliminary results. To further this study, we propose 5 specific Aims. (1) Synthesize O-methylated GTP analogs (by replacing -OH with -OCH3), the deoxy compounds (without the catechol diol), and polyphenol homologs (replacing -OH with -CH2OH) and determine their binding affinity to the proteasomal b5 subunit by employing computational modeling. (2) Evaluate potencies of these synthetic compounds to inhibit the proteasome activity using purified 20S proteasome, breast cancer cell extracts, and intact breast cancer cells. (3) Evaluate the apoptosis-inducing potencies of these synthetic compounds in human breast cancer cells. (4) Determine the effects of over- and under-expression of COMT gene in cultured human breast cancer cells on methylation of GTPs and their proteasome-inhibitory and apoptosis-inducing activities. (5) Determine whether methylation of GTPs is a mechanism to inactivate their biological functions in vivo using nude mice bearing human breast tumor xenografts. These studies should help develop a fundamental understanding about how the polymorphic COMT regulates the biological functions of GTPs in breast cancer cells and the impact of GTP methylation by COMT on the cancer- preventative effects of tea consumption as well as generate important information for designing future cancer prevention clinical trials using GTPs alone or in combination with a COMT inhibitor.

描述（由申请人提供）：研究支持蛋白酶体抑制剂作为潜在的新型抗癌药物和绿茶多酚（GTP）作为癌症预防剂。我们已经报道过 GTP，例如(-)-表没食子儿茶素-3-没食子酸酯或 EGCG 是蛋白酶体胰凝乳蛋白酶样活性（由 b5 亚基介导）的有效且特异性抑制剂。 GTP 的甲基化是一种限制其体内癌症预防活性的主要生物转化反应，由人多态儿茶酚-O-甲基转移酶 (COMT) 介导。点突变 COMT 存在于 -25% 的美国人口中，其酶活性降低了 3-4 倍 (COMT-LL)。据报道，与不喝茶的人相比，至少携带一种低活性 COMT 等位基因（但不是 COMT-HH）的女性饮茶者患乳腺癌的风险显着降低，这表明甲基化多酚的保护作用较小。为了研究其机制，我们假设乳腺癌细胞中 COMT 对 GTP 的 O-甲基化降低了它们的蛋白酶体抑制作用，从而降低了生物活性。我们的初步结果支持了这一假设。为了进一步开展这项研究，我们提出了 5 个具体目标。 (1) 合成O-甲基化GTP类似物（用-OCH3替换-OH）、脱氧化合物（不含儿茶酚二醇）和多酚同系物（用-CH2OH替换-OH）并测定它们与蛋白酶体b5亚基的结合亲和力通过采用计算模型。 (2) 使用纯化的 20S 蛋白酶体、乳腺癌细胞提取物和完整乳腺癌细胞评估这些合成化合物抑制蛋白酶体活性的效力。 (3) 评估这些合成化合物在人乳腺癌细胞中诱导细胞凋亡的效力。 (4)确定培养的人乳腺癌细胞中COMT基因的过表达和低表达对GTP甲基化及其蛋白酶体抑制和凋亡诱导活性的影响。 (5)利用携带人乳腺肿瘤异种移植物的裸鼠确定GTPs的甲基化是否是使其体内生物学功能失活的机制。这些研究应有助于对多态性 COMT 如何调节乳腺癌细胞中 GTP 的生物学功能以及 COMT 的 GTP 甲基化对饮茶防癌作用的影响有一个基本的了解，并为设计未来的癌症提供重要信息单独使用 GTP 或与 COMT 抑制剂联合使用的预防临床试验。