GLUTATHIONE TRANSFERASE FUNCTIONS IN CHEMOPROTECTION

一些已知的化学预防剂被假设为工作 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作用 研究人员利用转基因细胞系， GST表达可提供有效保护以对抗DNA烷基化 在某些情况下，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和特异性药物。 然而，结果表明，影响商品及服务税保护的因素是 复杂，并随不同的代理和端点而变化。概述的研究 该提案将提供关于以下方面的有效性和特异性的新信息： 人GSTP 1或GSTM 1对DNA加合物形成或细胞毒性的保护 由暴露于由共表达的大鼠rCYP 1A1原位激活的PAH引起，或 人hCYP 1A1。V79细胞GST同工酶的异质性表达 先前用rCYP1A1或hCYP1A1稳定转染的细胞将用作 实验模型系统重要的是，这些信息将直接 与GST同工酶表达对代谢产物的影响相比， 在细胞中，这可能与细胞蓄积和细胞终点（如细胞毒性）有关。他们 假设GST系统的功效取决于多个 因素，而不仅仅是特定底物的酶促效率。 下一个供资期将研究其中几个因素，包括 转染GST同工酶的抗肿瘤保护作用与肿瘤细胞凋亡的关系 结果：（1）GST蛋白表达水平，（2）阳性率和阳性部位 活化与解毒的关系，以及由此产生的代谢产物谱和/或 水平，3）细胞因子：谷胱甘肽（GSH）的供应，和/或流出 GSH-缀合物，和4）影响活性位点的遗传多态性 hGST P1 - 1的结构。这些研究将提供一个详细的了解关键 影响转染细胞中GST保护功效的参数，并且应当 有助于确定针对各种不同的 检查细胞损伤终点。

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.