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

• 批准号: 7355585
• 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
• 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/7355585
• 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

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.

研究支持蛋白酶体抑制剂作为潜在的新型抗癌药和绿茶 多酚（GTP）作为癌症预防剂。我们报道了GTP，例如（ - ） - epigallocatechin- 3-gallate或eGCG是蛋白酶体辣椒蛋白蛋白酶样活性的有效和特异性抑制剂（由 B5亚基）。 GTP的甲基化，这是一种主要的生物转化反应，限制了其癌症预防 体内的活性是由人类多态性儿茶醇-O-甲基转移酶（COMT）介导的。点 - 在-25％的美国人群中发现的突变COMT酶活性降低了3-4倍（COMT-LL）。它 据报道，具有至少一个低活动COMT等位基因（但没有COMT-HH）的女性茶饮者显示 与非TEA饮酒者相比，乳腺癌的风险大大降低，表明通过 甲基化的多酚。为了研究负责任的机制，我们假设GTPS的O-甲基化 通过COMT在乳腺癌细胞中降低了其蛋白酶体抑制性，因此降低了生物学活性。 我们的初步结果支持了这一假设。为了进一步，我们提出了5个具体目标。 （1） 合成o-甲基化的GTP类似物（通过用-och3替换-OH），脱氧化合物（没有 Catechol Diol）和多酚同源物（用-CH2OH替换-OH）并确定其结合亲和力 通过采用计算建模来实现蛋白酶体B5亚基。 （2）评估这些功能 合成化合物使用纯化的20S蛋白酶体抑制蛋白酶体活性 提取物和完整的乳腺癌细胞。 （3）评估这些合成的凋亡诱导效力 人类乳腺癌细胞中的化合物。 （4）确定COMT过表达的影响 培养的人类乳腺癌细胞中GTP及其蛋白酶体抑制性甲基化的基因 凋亡诱导活动。 （5）确定GTP的甲基化是否是使其失活的机制 使用带有人乳腺肿瘤异种移植物的裸小鼠在体内的生物学功能。这些研究应该 有助于建立对多态性COMT如何调节生物学的基本了解 GTP在乳腺癌细胞中的功能以及COMT对GTP甲基化对癌症的影响 - 茶消费的预防作用，并生成用于设计未来癌症的重要信息 单独或与COMT抑制剂结合使用GTP的预防临床试验。