GLUTATHIONE TRANSFERASE FUNCTIONS IN CHEMOPROTECTION

一些已知的化学预防药物被假定有效。 部分通过诱导谷胱甘肽-S-转移酶(GST)表达。按顺序 了解GST在细胞毒性和致突变性解毒中的作用 在亲电方面，研究人员利用转基因细胞系展示了 GST的表达可以对DNA烷基化提供有效的保护 在某些情况下，由亲电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，影响GST保护作用的因素是 复杂，并且随不同的代理和终端而异。中概述的研究 这项建议将提供有关药物疗效和特异性的新信息。 人GSTP1或GSTM1对DNA加合物形成或细胞毒的保护作用 暴露于共表达的大鼠rCYP1A1或rCYP1A1原位激活的PAHs 人hCYP1A1。谷胱甘肽转移酶同工酶在V79细胞中的异源表达 以前稳定地转染了rCYP1A1或hCYP1A1的人将被用作 实验模型系统。重要的是，这些信息将直接 GST同工酶表达对代谢产物影响的比较 在细胞内的蓄积和细胞终点，如细胞毒性。他们 假设商品及服务税系统的有效性依赖于 因素，而不仅仅是酶的效率与特定的底物。 将在下一个供资期间审查其中几个因素，包括 转染型GST同工酶对小鼠的保护作用 以上终点和1)GST蛋白表达水平，2)速率和位置 激活与解毒的对比，以及所产生的代谢物特征和/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)影响活性部位的遗传多态 HGSTP1-1的结构。这些研究将提供对关键技术的详细了解 在转基因细胞中影响GST保护效果的参数，并且应该 有助于确定针对不同类型的病毒观察到的差异保护机制 细胞损伤终点检查。

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.