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: 7909204
• 负责人: QING PING DOU
• 金额: $ 26.33万
• 依托单位: WAYNE STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7909204
• 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 Culture Techniques; Cell Cycle; Cell Death; Cell Extracts; Cells; Cessation of life; Clinical; Computer Simulation; Consumption; Data; Disease; Doctor of Philosophy; Epidemiologic Studies; Epigallocatechin Gallate; Esters; Future; General Population; Genotype; Glycols; 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; Oncogenes; Organism; Pathway interactions; Patients; Peptide Hydrolases; Peptides; Phase I/II Trial; Phase III Clinical Trials; Population; Process; Property; Proteasome Inhibitor; Proteins; Reaction; Reporting; Research; Research Personnel; Resistance; Risk; Role; Series; Stimulus; Structure; Study Section; Tea; Testing; Trypsin; Ubiquitin; United States; Woman; Xenograft procedure; analog; base; 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的有效且特异性抑制剂（由 b5 亚基）。 GTP 的甲基化是一种主要的生物转化反应，限制了其防癌作用 体内活性由人多态性儿茶酚-O-甲基转移酶（COMT）介导。重点是—— 突变的 COMT 存在于 -25% 的美国人口中，其酶活性降低了 3-4 倍 (COMT-LL)。它 据报道，至少具有一个低活性 COMT 等位基因（但不是 COMT-HH）的女性饮茶者表现出 与不喝茶的人相比，患乳腺癌的风险显着降低，这表明喝茶的保护较少 甲基化多酚。为了研究其机制，我们假设 GTP 的 O-甲基化 COMT 在乳腺癌细胞中的作用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（通过用 -OCH3 替换 -OH）、脱氧化合物（不含 儿茶酚二醇）和多酚同系物（用 -CH2OH 代替 -OH）并测定它们的结合亲和力 通过计算模型将其转化为蛋白酶体 b5 亚基。 (2) 评估这些的效力 使用纯化的 20S 蛋白酶体合成化合物抑制蛋白酶体活性，乳腺癌细胞 提取物和完整的乳腺癌细胞。 (3) 评估这些合成的细胞凋亡诱导能力 人类乳腺癌细胞中的化合物。 (4)确定COMT过表达和低表达的影响 培养的人乳腺癌细胞中 GTP 甲基化及其蛋白酶体抑制和 细胞凋亡诱导活性。 (5) 确定GTPs的甲基化是否是使其失活的机制 使用携带人乳腺肿瘤异种移植物的裸鼠进行体内生物学功能。这些研究应该 帮助对多态 COMT 如何调节生物 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 喝茶的预防作用以及为设计未来癌症提供重要信息 单独使用 GTP 或与 COMT 抑制剂联合使用的预防临床试验。