Carcinogenic Metabolites Formed from Antiestrogen

描述（由申请人提供）：“完美”选择性雌激素受体调节剂（SERM）的开发对绝经后妇女的健康至关重要。SERM的有益和不期望的副作用直接类似于雌激素，雌激素通过涉及氧化代谢为氧化还原活性/亲电子醌类化合物的机制是已知的致癌物。我们推测，SERMs的不良反应也与其氧化代谢为醌类化合物有关。这些醌类化合物是否有害目前尚不清楚，本提案的重点是确定结构对这些机制的影响，以提供导致“完美”SERM发展的关键信息。具体目标是：1.结构对SERM醌类化合物的形成和反应性的影响。我们已经表明，经典的醌甲基化物，二醌甲基化物，邻醌产生的三苯乙烯，苯并噻吩，和杂项SERM。我们计划检查新类别的SERMs，如bazodoxifene和lasofoxifene以及礼来萘酚类似物被氧化为醌类化合物的相对能力。将在亚细胞组分和石川子宫内膜细胞中研究醌类化合物的形成速率、类型及其反应性。2. SERM醌类化合物的蛋白质靶点是什么？在目前的提案中，我们计划使用COATag方法和“点击化学”或修改的Staudinger连接方法来检查大鼠乳腺亚细胞组分和石川细胞中的蛋白质共价修饰。目标蛋白将使用亲和素亲和层析分离，分离的2D电泳，消化，并通过MALDI-TOF和LC-MS-MS分析。我们预测，SERM醌类化合物的反应性将有很强的影响，蛋白质被修改，以及在目标蛋白质内的蛋白质烷基化位点。3. SERM醌类化合物修饰DNA并诱导细胞转化吗？这一目标将集中在如何形成的SERM醌的类型和反应性将决定DNA损伤的程度。最初的模型研究与脱氧核苷和DNA将允许表征稳定的DNA加合物，分析脱嘌呤加合物，以及确定DNA氧化。然后，我们将在石川细胞系中分析SERM诱导的DNA损伤。脱嘌呤位点（AP）将使用醛反应性探针试验直接定量，这些致突变病变导致的颠换和转换将通过错配捕获方法检测。最后，将在MCF-10A细胞中进行转化研究，并将转化的克隆植入无胸腺裸鼠中，以研究其诱导肿瘤形成的能力。这些研究将阐明醌式化合物形成和每个SERM的细胞靶点的相对重要性，从而使反应性与结构之间的相关性成为可能，从结构中将出现影响SERM醌式化合物在细胞中行为的一般原则。公共卫生相关性：为了预防骨质疏松症、心血管疾病和潮热，“完美”SERM的发展对绝经后妇女的健康至关重要。然而，一些SERM通过形成反应性化合物增加了某些癌症的风险。本提案的重点是研究这些潜在的致癌活性化合物，以提供导致“完美”SERM发展的关键信息。

DESCRIPTION (provided by applicant): Development of the "perfect" selective estrogen receptor modulator (SERM) is of paramount importance in postmenopausal women's health. The beneficial and undesirable side effects of SERMs are directly analogous to estrogens, which are known carcinogens through a mechanism involving oxidative metabolism to redox active/electrophilic quinoids. We hypothesize that the adverse effects of SERMs are also related to their oxidative metabolism to quinoids. Whether these quinoids are detrimental are unknown at this time and it is the focus of this proposal to determine the effect of structure on these mechanisms in an effort to provide crucial information leading to the development of the "perfect" SERM. The specific aims are: 1. Effect of structure on the formation and reactivity of SERM quinoids. We have shown that classical quinone methides, di-quinone methides, and o-quinones are produced from triphenylethylene, benzothiophene, and miscellaneous SERMs. We plan to examine the relative abilities of new classes of SERMs such as bazodoxifene and lasofoxifene as well as the Lilly naphthol analogs to be oxidized to quinoids. The rate of formation, type of quinoid, as well as their reactivity will be studied in subcellular fractions and Ishikawa endometrial cells. 2. What are the protein targets of SERM quinoids? In the current proposal, we plan to use the COATag methodology and "click chemistry" or modified Staudinger ligation approaches to examine protein covalent modification in rat mammary subcellular fractions and Ishikawa cells. The targeted proteins will be isolated using avidin affinity chromatography, separated by 2D electrophoresis, digested, and analyzed by MALDI-TOF and LC-MS-MS. We predict that the reactivity of SERM quinoids will have a strong influence on which proteins are modified as well as sites of protein alkylation within the target proteins. 3. Do SERM quinoids modify DNA and induce cellular transformation? This aim will focus on how the type and reactivity of SERM quinoid formed will dictate the extent of DNA damage. Initial model studies with deoxynucleosides and DNA will allow characterization of stable DNA adducts, analysis of depurinating adducts, as well as determination of DNA oxidation. We will then analyze SERM-induced DNA damage in Ishikawa cell lines. Apurinic sites (AP) will be directly quantified using the aldehyde reactive probe assay and the transversions and transitions resulting from these mutagenic lesions will be detected by mismatch-capture methodology. Finally, transformation studies will be performed in MCF-10A cells and the transformed clones will be implanted into athymic nude mice to investigate their ability to induce tumor formation. These studies will elucidate the relative importance of quinoid formation and cellular targets for each SERM, thereby enabling correlations of reactivity with structure from which general principles influencing the behavior of SERM quinoids in cells will emerge. PUBLIC HEALTH RELEVANCE: Development of the "perfect" SERM is of paramount importance in postmenopausal women's health in order to prevent osteoporosis, cardiovascular disease, and hot flashes. However, some SERMs increases the risk of some cancers through formation of reactive compounds. It is the focus of this proposal to investigate these potentially carcinogenic reactive compounds in an effort to provide crucial information leading to the development of the "perfect" SERM.