Aryl and Alcohol Sulfotransferases in Drug Metabolism

描述(申请人提供)：磺基转移酶在许多药物的解毒以及在许多化学致癌物的代谢激活中的作用越来越被认为是非常重要的。硫化是异物代谢形成细胞毒性、致突变和/或致癌分子的关键成分，包括烷基取代多环芳烃衍生的苄醇、芳香胺和硝基芳香烃的羟胺代谢物以及烯丙醇。这项研究的长期目标是更全面地了解和预测芳基和醇磺基转移酶在外源化合物的细胞毒性、诱变和/或致癌作用中所起的作用，这些外源物质要么拥有要么被生物转化为含有苯甲醇、烯丙醇和N-羟基芳胺官能团的代谢物。下一个项目期拟议工作的主要目标是解决我们在通过基因表达和等位基因变异以外的方法调节这些磺基转移酶的催化功能方面的知识空白。这项研究是基于一个中心假设，即芳基和醇磺酸转移酶识别底物和抑制剂的立体专一性、这些酶的氧化环境以及共底物PAPs的动力学调节是预测药物代谢和化学致癌中硫酸盐化速率的关键组成部分。在接下来的项目期内，这项研究的具体目的是：1)继续阐明三苯氧胺衍生的烯丙基α-羟化代谢物与大鼠STA和人SULT2A1醇转移酶相互作用的立体选择性，并研究他莫昔芬及其代谢产物对这些酶的抑制作用；2)确定PAPS浓度在催化调节大鼠和人酒精转移酶中的作用；3)确定芳基和醇转移酶中二硫键形成导致动力学变化的程度和意义，以及4)基于定量结构-活性关系设计芳基和醇转移酶异构体特异性抑制剂。这项研究的结果将为研究芳基和醇基磺基转移酶催化功能的动态调节机制提供重要的新见解，这两种酶在药物代谢和化学致癌中具有重要作用，并将为设计磺基转移酶的异构体特异性抑制剂提供新的方法。因此，该项目与公众健康高度相关，因为它提供了对硫酸盐化在药物代谢和外源物质向化学致癌物代谢中的作用的更多了解和预测。此外，特定的目标#1对于了解和更准确地预测他莫昔芬的代谢具有额外的特殊相关性，他莫昔芬是一种广泛使用的抗肿瘤药物和雌激素依赖型乳腺癌的化学预防药物。

DESCRIPTION (provided by applicant): The roles of sulfotransferases in detoxication of many drugs, as well as in the metabolic activation of many chemical carcinogens, are increasingly recognized as highly significant. Sulfation is a key component in the metabolic formation of cytotoxic, mutagenic and/or carcinogenic molecules from xenobiotics that include benzylic alcohols derived from alkyl-substituted polycyclic aromatic hydrocarbons, hydroxylamine metabolites of aromatic amines and nitroaromatics, and allylic alcohols. The long-term goal of this research is to more fully understand and predict the roles that aryl and alcohol sulfotransferases play in the cytotoxic, mutagenic, and/or carcinogenic effects of xenobiotics that either possess or are biotransformed into metabolites containing benzylic alcohol, allylic alcohol, and N-hydroxy arylamine functional groups. The primary objective of the work proposed for the next project period is to address the gaps in our knowledge of the regulation of the catalytic function of these sulfotransferases by means other than gene expression and allelic variations. The proposed investigation is based on the central hypothesis that stereospecificity in recognition of substrates and inhibitors by aryl and alcohol sulfotransferases, the oxidative environment of these enzymes, and kinetic regulation by the co-substrate, PAPS, are critical components in the prediction of the rates of sulfation in drug metabolism and chemical carcinogenesis. The specific aims of the research during the upcoming project period are to 1) continue elucidation of the stereoselectivity of interactions of allylic alpha-hydroxylated metabolites derived from Tamoxifen with rat STa and human SULT2A1 alcohol sulfotransferases and study the inhibition of these enzymes by Tamoxifen and its metabolites, 2) determine the role of the concentration of PAPS in the catalytic regulation of rat and human alcohol sulfotransferases, 3) determine the extent and significance of changes in kinetics resulting from disulfide bond formation in aryl and alcohol sulfotransferases, and 4) develop methods for design of isoform-specific inhibitors of aryl and alcohol sulfotransferases based on quantitative structure-activity relationships. The results of this research will provide significant new insight into the mechanisms for dynamic regulation of the catalytic function of aryl and alcohol sulfotransferases that are important to drug metabolism and chemical carcinogenesis as well as new methodology for the design of isoform-specific inhibitors of sulfotransferases. Thus, this project is highly relevant to public health due to its provision of increased understanding and prediction of the roles of sulfation both in drug metabolism and in the metabolism of xenobiotics to chemical carcinogens. Moreover, specific aim #1 has additional particular relevance to understanding and more accurately predicting the metabolism of Tamoxifen, a widely used antitumor agent and chemopreventive agent for estrogen-dependent breast cancer.