Regulation of Transcriptional Coactivators by Environmental Estrogens (R21)

描述(由申请人提供)： 核激素受体的活性受辅助蛋白调节，如组蛋白乙酰转移酶和精氨酸甲基转移酶，它们作为这些受体的辅助激活因子，参与激素反应性肿瘤的进展。这种活性部分是由蛋白质精氨酸甲基转移酶(PRMTs)，PRMT1和CARM1，在体内甲基化组蛋白的能力促进的，这些共激活子是药物开发的潜在靶点。异种雌激素是一种来源于植物或人工合成的化合物，通常与哺乳动物的主要雌激素--17β-雌二醇结构相似。最近，高通量筛选PRMT亚类共激活剂的小分子抑制剂。这些抑制剂中的大多数是多酚，其中一种特别的(AMI-18)与一组异种雌激素具有共同的额外特征。因此，一组外来雌激素被测试，其中大量被发现在体外抑制PRMT的活性。在这项研究中，目的是评估外源雌激素和SERM调节重组蛋白和细胞内甲基转移酶和乙酰基转移酶活性的能力。将使用的技术包括体外甲基化分析、转录报告分析、染色质沉淀(CHIP)实验和RT-PCR。在这一探索性/发展性研究提案中，将研究一些异种雌激素既能与雌激素受体(ER)结合(从而干扰转录)又能抑制共激活剂活性(从而抑制转录)的新想法。这增加了与最好的拮抗剂和最好的辅助激活物抑制剂联合治疗的可能性，特别是对激素依赖型肿瘤，如乳腺癌和前列腺癌。其具体目的是表征：1)生物化学上的异种雌激素作为辅助激活抑制剂；以及2)在体外作为辅助激活抑制剂的异种雌激素。

DESCRIPTION (provided by applicant): Nuclear hormone receptor activity is regulated by accessory proteins such as histone acetyltransferases and arginine methyltransferases, that function as coactivators for these receptors and such are involved in hormone responsive tumor progression. This activity is facilitated in part by the ability of the protein arginine methyltransferases (PRMTs), PRMT1 and CARM1, to methylate histones in vivo and these coactivators are potential targets for drug development. Xenoestrogens are compounds of plant or synthetic origin that often share structural similarity with the principal mammalian estrogen, 17beta-estradiol. Recently, a high throughput screen for small-molecule inhibitors of the PRMT sub-class of coactivators was performed. The majority of these inhibitors were polyphenols, and one in particular (AMI-18) shared additional features with a group of xenoestrogens. Thus a panel of xenoestrogens was tested and a large number of them found to inhibit PRMT activity in vitro. In this study, the intent is to evaluate the ability of xenoestrogens and SERMs to regulate methyltransferase and acetyltransferase activities of recombinant proteins and in cells. Techniques to be used will include in vitro methylation assays, transcriptional reporter assays, chromatin precipitation (ChIP) experiments and RT-PCR. In this exploratory/developmental research proposal the novel idea that some xenoestrogens posses the ability to both bind the estrogen receptor (ER) (thus perturbing transcription) and inhibit co-activator activity (thereby suppressing transcription) will be investigated. This raises the possibility that combination treatment with the best antagonists the best co-activator inhibitors may be of therapeutic value particularly for hormone-dependent tumors, like breast and prostate cancers. The specific aims are to characterize: 1) Biochemically xenoestrogens as co-activator inhibitors; and 2) In vitro xenoestrogens as co-activator inhibitors.