Androgen Signaling and Coactivator Regulation in PCA

PCA 中的雄激素信号转导和共激活因子调节

• 批准号: 8142674
• 负责人: Hsing-Jien Kung
• 金额: $ 0.94万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-01 至 2015-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8142674
• 关键词: Androgen; Signaling; Coactivator; Regulation; PCA

DESCRIPTION (provided by applicant): Androgen receptor plays a significant role in prostate carcinogenesis and its overexpression and aberrant activation are considered to be the underlying cause for the development of castration-resistant tumors, which at present defy any effective treatment. As a transcriptional factor, androgen receptor is involved in the assembly of transcriptional complex including coactivators on the target genome site. One special class of coactivators are histone modifying enzymes and the best understood are histone acetylases. A newly emerging class is histone demethylase, which serves to remodel the chromatin surrounding the androgen receptor binding site. They are thus both transcriptional coactivator and epigenetic regulator. The present proposal is based on our identification of a new histone demethylase with all the hallmarks of a strong coactivator of androgen receptor and is overexpressed in prostate cancer. It enhances androgen response, accelerates cell cycle progression, and exhibits a substrate specificity different from the known histone demethylases. Intriguingly, it is regulated by growth factor and is phosphorylated by tyrosine kinases. The enzyme is cell cycle regulated but also regulates cell cycle. Based on these preliminary observations, we wish to elucidate its biochemical properties as a demetylation enzyme, its regulation as a signal transducer, and its biological effects as an androgen receptor coactivator. Its potential as a biomarker and/or a target for therapy will also be evaluated. PUBLIC HEALTH RELEVANCE: Increasing evidence suggests that over 90% of castration-resistant prostate cancers have evolved ways to aberrantly activate androgen receptor either due to androgen receptor mutations, amplification, increase of intracrine androgen, posttranslational modification of androgen receptor or association of deregulated coactivators. Thus, targeting aberrantly activated androgen receptor or its dysregulated coactivators is likely to be the most fruitful strategy to interfere with the development of hormone-refractory tumors. Strategy to interfere with ligand binding is one option, but it fails to target truncated androgen receptor. Targeting co-activators is another strategy, but most of the co-activators are not enzymes, which makes the development of small-molecule inhibitors more difficult. Our finding that histone demethylase, an enzyme, is a coactivator thus offers an ideal target for this intervention. If SAHA, an inhibitor for histone deacetylase and a clinically approved drug, is a pertinent example, this new histone demethylase could be an ideal enzyme-based target for prostate cancer. Their consistent overexpression in prostate cancer specimens shown in our preliminary data suggests it could also potentially be a good biomarker for aberrant activation of androgen receptor. The overall relevance of this proposal to prostate cancer includes : 1) It offers a new handle to understand the epigenetic regulation of androgen receptor activity and thus prostate cancer development. 2) It offers a potentially new biomarker for transformation and/or aberrant activation of androgen receptor in the prostate carcinogenesis, and 3) It offers a potentially new enzyme-based target for interfering with prostate carcinogenesis.

描述（申请人提供）：雄激素受体在前列腺癌发生中发挥重要作用，其过度表达和异常激活被认为是去势抵抗性肿瘤发展的根本原因，目前尚无任何有效的治疗方法。作为转录因子，雄激素受体参与转录复合物的组装，包括靶基因组位点上的共激活子。一类特殊的共激活剂是组蛋白修饰酶，最了解的是组蛋白乙酰酶。新出现的一类是组蛋白去甲基酶，它可以重塑雄激素受体结合位点周围的染色质。因此它们既是转录共激活因子又是表观遗传调节因子。目前的提议是基于我们鉴定出一种新的组蛋白去甲基酶，该酶具有雄激素受体强共激活剂的所有特征，并且在前列腺癌中过度表达。它增强雄激素反应，加速细胞周期进程，并表现出与已知组蛋白去甲基酶不同的底物特异性。有趣的是，它受生长因子调节，并被酪氨酸激酶磷酸化。该酶受细胞周期调节，但也调节细胞周期。基于这些初步观察，我们希望阐明其作为去甲基化酶的生化特性、其作为信号转导器的调节以及其作为雄激素受体共激活剂的生物效应。还将评估其作为生物标志物和/或治疗靶点的潜力。 公共健康相关性：越来越多的证据表明，超过 90% 的去势抵抗性前列腺癌已经进化出异常激活雄激素受体的方式，这可能是由于雄激素受体突变、扩增、分泌内雄激素增加、雄激素受体翻译后修饰或失调的共激活剂的关联所致。因此，针对异常激活的雄激素受体或其失调的共激活剂可能是干扰激素难治性肿瘤发展的最有效策略。干扰配体结合的策略是一种选择，但它无法靶向截短的雄激素受体。靶向共激活剂是另一种策略，但大多数共激活剂不是酶，这使得小分子抑制剂的开发更加困难。我们发现组蛋白去甲基酶（一种酶）是一种共激活剂，因此为这种干预提供了理想的目标。如果组蛋白脱乙酰酶抑制剂和临床批准药物 SAHA 是一个相关的例子，那么这种新的组蛋白脱甲基酶可能是前列腺癌理想的基于酶的靶标。我们的初步数据显示，它们在前列腺癌标本中持续过度表达，表明它也可能是雄激素受体异常激活的良好生物标志物。该提案与前列腺癌的总体相关性包括：1）它为理解雄激素受体活性的表观遗传调控以及前列腺癌的发展提供了新的途径。 2) 它为前列腺癌发生过程中雄激素受体的转化和/或异常激活提供了一个潜在的新生物标志物，3) 它为干扰前列腺癌发生提供了一个潜在的新的基于酶的靶标。