GLUTATHIONE TRANSFERASE FUNCTIONS IN CHEMOPROTECTION

谷胱甘肽转移酶在化学保护中的功能

• 批准号: 6350837
• 负责人: ALAN J TOWNSEND
• 金额: $ 22.09万
• 依托单位: WAKE FOREST UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-02-01 至 2004-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6350837
• 关键词: DNA damage; active sites; adduct; cancer risk; carbopolycyclic compound; carcinogenesis inhibitor; cell line; chemoprevention; cytochrome P450; cytotoxicity; enzyme activity; enzyme induction /repression; gene environment interaction; genetic polymorphism; glutathione transferase; isozymes; pharmacokinetics; toxin metabolism; transfection

A number of known chemopreventive agents are hypothesized to work in part via induction of glutathione-S-transferase (GST) expression. In order to understand the functions of GST in detoxification of cytotoxic and mutagenic electrophiles, the investigators have utilized transgenic cell lines to show that GST expression can provide efficacious protection against DNA alkylation and, in some cases, cytotoxicity caused by electrophilic carcinogens that are GST substrates, including 4-NQO, B[a]P, BPDE, AFB1, CDNB, and specific drugs. However, the results indicated that the factors governing protection by GST are complex and vary with different agents and endpoints. The studies outlined in this proposal will provide new information on the efficacy and specificity of human GSTP1 or GSTM1 protection against DNA adduct formation or cytotoxicity caused by exposure to PAHs activated in situ by co-expressed rat rCYP1A1 or human hCYP1A1. Heterologous expression of the GST isozymes in V79 cells previously stably transfected with rCYP1A1 or hCYP1A1 will be used as the experimental model system. Importantly, this information will be directly compared with the effects of GST isoenzyme expression on metabolite accumulation and with cellular end-points, such as cytotoxicity, in cells. They hypothesize that the efficacy of the GST system is dependent on multiple factors and not only the enzymatic efficiency with a particular substrate. Several of these factors will be examined in the next funding period, including the relationship between protection by transfected GST isozymes against the above end-points and 1) the level of GST protein expressed, 2) rates and site of activation vs. detoxification, and resultant metabolite profiles and/or levels, 3) cellular factors: glutathione (GSH) supply, and/or efflux of GSH-conjugates, and 4) genetic polymorphisms that affect the active site architecture of hGSTP1-1. These studies will provide a detailed understanding of key parameters affecting the efficacy of GST protection in the transfected cells, and should help to identify the mechanisms of differential protection observed against the various cellular injury end-points examined.

假设许多已知的化学预防剂有效 部分通过诱导谷胱甘肽-S-转移酶 (GST) 表达。为了 了解 GST 在细胞毒性和致突变性解毒中的功能 研究人员利用转基因细胞系来证明 GST 表达可以提供有效的保护，防止 DNA 烷基化 在某些情况下，由亲电子致癌物引起的细胞毒性 GST 底物，包括 4-NQO、B[a]P、BPDE、AFB1、CDNB 和特定药物。 然而，结果表明，商品及服务税保护的影响因素是 复杂并且随着不同的代理和端点而变化。中概述的研究 该提案将提供关于有效性和特异性的新信息 人类 GSTP1 或 GS​​TM1 防止 DNA 加合物形成或细胞毒性 由暴露于共表达大鼠 rCYP1A1 原位激活的 PAH 引起，或 人 hCYP1A1。 V79 细胞中 GST 同工酶的异源表达 之前用rCYP1A1或hCYP1A1稳定转染的细胞将被用作 实验模型系统。重要的是，这些信息将直接 与GST同工酶表达对代谢物的影响进行比较 积累和细胞终点，例如细胞毒性。他们 假设商品及服务税制度的有效性取决于多种因素 因素而不仅仅是特定底物的酶促效率。 其中几个因素将在下一个资助期内进行审查，包括 转染的 GST 同工酶对 GST 的保护作用之间的关系 以上终点和 1) GST 蛋白表达水平，2) 比率和位点 激活与解毒的比较，以及由此产生的代谢物谱和/或 水平，3) 细胞因素：谷胱甘肽 (GSH) 供应和/或外流 GSH 结合物，以及 4) 影响活性位点的遗传多态性 hGSTP1-1 的架构。这些研究将提供对关键的详细了解 影响转染细胞中 GST 保护功效的参数，并且应该 有助于确定针对各种不同情况观察到的差别保护机制 检查细胞损伤终点。