Carcinogenic Metabolites formed from Antiestrogens

抗雌激素形成的致癌代谢物

• 批准号: 6582106
• 负责人: Judy L Bolton
• 金额: $ 27.11万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-08 至 2007-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6582106
• 关键词: DNA damage; alkylation; biochemistry; breast neoplasms; carcinogenesis; cell line; chemical structure; cofactor; cytotoxicity; drug adverse effect; estrogen inhibitor; estrogen receptors; free radical oxygen; hormone related neoplasm /cancer; laboratory rat; liver; oxidation reduction reaction; quinones; raloxifene; tamoxifen; uterus neoplasms; women's health

DESCRIPTION (provided by applicant): Tamoxifen remains the endocrine therapy of choice in the treatment of all stages of hormone-dependent breast cancer. In addition, clinical trials are in progress to determine the potential of tamoxifen to act as a chemopreventive agent in women considered at high risk for developing breast cancer. However, several studies have raised concern over the safety of chronic treatment with this drug. Alternative SERMs may not be genotoxic because of different routes of metabolism that could lead to a decrease in amount and/or type of ultimate carcinogen(s). The central hypothesis of this project is that the formation of quinoids is an important mechanism of carcinogenesis and or cytotoxicity, for certain antiestrogens. For example, tamoxifen can be metabolized to three quinoids including two quinone methides and one o-quinone. The following specific aims are proposed: 1. Role of quinoids in the carcinogenic and cytotoxic effects of antiestrogens. We plan to examine the carcinogenic potential of quinoids formed from SERMs in cell lines. The biochemical effects of the antiestrogen quinoids will be investigated in human breast and endometrial cancer cell lines, which are either estrogen receptor positive or negative. 2. Investigate the effect of quinoids structure on electrophilic and/or redox reactivity. The rates of reaction of the SERM quinoids with water and GSH will be measured. Reactions of selected intermediates with either estrogenic or antiestrogenic activity with deoxynucleosides and DNA will also be investigated and adduct structures elucidated. Redox active metabolites will be tested by monitoring changes in the concentrations of reduced cofactors, determining the formation of reactive oxygen species, and examining oxidative damage to DNA. 3. Determine if the antagonist/agonist activity of antiestrogen metabolites correlates with the extent of DNA damage in cell lines. We predict that excessive binding to the estrogen receptor, which then translocates to the nucleus, will be correlated with an increase in DNA damage. The Ishikawa cell system will be used to determine the estrogenic or antiestrogenic effect of the SERM metabolites. The results from the Ishikawa cell experiments will be compared to studies measuring binding of the antiestrogen metabolites to the estrogen receptors. Cellular DNA from estrogen receptor positive and negative cells lines will be isolated after treatment with the test compound. The DNA will be hydrolyzed to deoxynucleosides and examined for DNA damage. Finally, we will determine the extent of DNA damage induced in vivo by the most carcinogenic/cytotoxic antiestrogen metabolites using the rat liver model. These studies will elucidate the relative importance of alkylation and free radical formation for each antiestrogen, thereby enabling correlations of reactivity with structure from which general principles influencing the behavior of antiestrogen reactive metabolites in cells will emerge.

描述（由申请人提供）：他莫昔芬仍然是治疗所有阶段的激素依赖性乳腺癌的首选内分泌疗法。此外，临床试验正在进行中，以确定他莫昔芬作为乳腺癌高危女性化学预防剂的潜力。然而，一些研究对这种药物长期治疗的安全性提出了担忧。替代 SERM 可能不具有遗传毒性，因为不同的代谢途径可能会导致最终致癌物的数量和/或类型减少。该项目的中心假设是，对于某些抗雌激素来说，醌类化合物的形成是致癌和/或细胞毒性的重要机制。例如，他莫昔芬可以代谢为三种醌类化合物，包括两种醌甲基化物和一种邻醌。提出以下具体目标： 1. 醌类化合物在抗雌激素的致癌和细胞毒性作用中的作用。我们计划检查细胞系中 SERM 形成的醌类化合物的致癌潜力。抗雌激素醌类化合物的生化作用将在雌激素受体阳性或阴性的人类乳腺癌和子宫内膜癌细胞系中进行研究。 2. 研究醌式结构对亲电子和/或氧化还原反应性的影响。将测量 SERM 醌类化合物与水和 GSH 的反应速率。还将研究具有雌激素或抗雌激素活性的选定中间体与脱氧核苷和 DNA 的反应，并阐明加合物结构。将通过监测还原辅因子浓度的变化、确定活性氧的形成以及检查 DNA 的氧化损伤来测试氧化还原活性代谢物。 3. 确定抗雌激素代谢物的拮抗剂/激动剂活性是否与细胞系中 DNA 损伤的程度相关。我们预测，与雌激素受体的过度结合（然后转移到细胞核）将与 DNA 损伤的增加相关。 Ishikawa 细胞系统将用于确定 SERM 代谢物的雌激素或抗雌激素作用。石川细胞实验的结果将与测量抗雌激素代谢物与雌激素受体结合的研究进行比较。用测试化合物处理后，将分离来自雌激素受体阳性和阴性细胞系的细胞DNA。 DNA 将被水解为脱氧核苷并检查 DNA 损伤。最后，我们将使用大鼠肝脏模型确定最具致癌性/细胞毒性的抗雌激素代谢物在体内诱导的 DNA 损伤程度。这些研究将阐明每种抗雌激素的烷基化和自由基形成的相对重要性，从而实现反应性与结构的相关性，从中得出影响细胞中抗雌激素反应性代谢物行为的一般原理。