Biointeractions of Antiestrogens with Nitric Oxide

描述（由申请人提供）：雌激素/激素替代疗法（HRT）用于绝经后症状的使用急剧下降，因为与激素和化学致癌相关的乳腺癌风险增加。选择性雌激素受体调节剂（SERMs）可以作为HRT的替代方案，但由于有致癌等副作用的风险，其发展已经停滞。苯并噻吩SERM （BT-SERM）雷洛昔芬是目前临床用于绝经后综合征和乳腺癌化学预防的唯一SERM。SERMs在某些组织中作为雌激素激动剂，雌激素和SERMs都被氧化代谢为亲电醌，具有产生ROS的潜力。雌激素激动剂已被证明可提高细胞NO；NO与乳腺癌肿瘤发生有关。醌类、活性氧和一氧化氮可以发生化学反应，也可以修饰蛋白质和破坏DNA。该建议旨在了解如何通过NO调节和适当设计具有氧化还原活性但本身不致癌的serm来减弱雌激素依赖性致癌作用，为设计用于HRT及其他用途的安全、非致癌serm提供基础。在Aim 1中，新的BT-SERMs将被合成并作为细胞探针进行分析。体外DNA损伤和蛋白修饰将通过LC-MS/MS进行研究。该目的将确定与（抗）雌激素产生的醌、NO和ROS化学相互作用的蛋白质和核酸加合物，以及醌结构对这些产物的影响，以便与aim 2在细胞培养中的结果进行比较。目的2将研究在乳腺细胞培养中导致细胞凋亡或恶性转化的氧化DNA损伤的调节。我们假设乳腺癌细胞的恶性转化反映了雌激素的化学致癌作用，因此可以预测在Aim 3计划的实验中，BT-SERM和NO调节治疗将减轻肿瘤发生。在Aim 3中，ACI大鼠，一个已建立的雌激素诱导的乳腺癌模型，将研究一种BT-SERM和NO调节对癌变和肿瘤消退的影响。

DESCRIPTION (provided by applicant): Use of estrogen/hormone replacement therapy (HRT) for post-menopausal symptoms has plummeted because of increased breast cancer risk associated with hormonal and chemical carcinogenesis. Selective estrogen receptor modulators (SERMs) could provide an alternative to HRT, but development has stalled because of the risk of side effects including carcinogenesis. The benzothiophene SERM (BT-SERM) raloxifene is currently the sole SERM in clinical use for postmenopausal syndrome and breast cancer chemoprevention. SERMs act as estrogen agonists in some tissues and both estrogens and SERMs are oxidatively metabolized to electrophilic quinones with potential to generate ROS. Estrogen agonists have been shown to elevate cellular NO; NO is implicated in breast cancer tumorigenesis. Quinones, ROS, and NO can interact chemically and also modify proteins and damage DNA. This proposal is directed at understanding how estrogen-dependent carcinogenesis can be attenuated by NO modulation and by appropriately designed SERMs that are redox-active but not themselves carcinogenic, to provide a basis for design of safe, non-carcinogenic SERMs for HRT and beyond. In Aim 1, new BT-SERMs will be synthesized and profiled as cellular probes. In vitro DNA damage and protein modification will be studied by LC-MS/MS. This aim will determine the protein and nucleic acid adducts of the chemical interaction with quinones, NO, and ROS generated by (anti)estrogens, and the influence of quinone structure on these products, allowing comparison with Aim 2 results in cell cultures. Aim 2 will study modulation of oxidative DNA damage in mammary cell cultures leading to apoptosis or malignant transformation. We hypothesize that malignant transformation of breast cancer cells reflects estrogen chemical carcinogenesis and therefore will be predictive for BT-SERM and NO modulating treatments that will attenuate tumorigenesis in experiments planned in Aim 3. In Aim 3, the ACI rat, an established model for estrogen-induced mammary carcinogenesis will be used to study the effect of one BT-SERM and NO modulation on carcinogenesis and tumor regression. PUBLIC HEALTH RELEVANCE: SERMs are a drug class used for postmenopausal syndromes and for prevention and therapy of estrogen dependent breast cancer. Risk-benefit ratios associated with estrogen replacement therapy and side effects of SERMs may be associated with tissue levels of nitric oxide (NO). The importance of this drug class demands a better understanding of the interactions of SERMs, estrogens, and NO as the foundation for improved therapeutic agents.