G-protein coupled receptor-30(GPR30):a putative new therapeutic target for PCa

描述(由申请人提供)： 前列腺癌(PCA)对退伍军人的医疗保健有重大影响，随着人口老龄化，其发病率将继续上升。尽管PCA疗法的开发不断取得进展，但雄激素剥夺疗法(ADT)抵抗疾病的患者选择有限。近年来，降低心血管毒性的雌激素在前列腺癌治疗中显示出很好的前景。在细胞膜和内质网中都发现了一种与雌激素高亲和力、低结合容量的孤儿G蛋白偶联受体(GPR30)。该受体被认为是雌激素的非基因组作用的关键中介。GPR30与配体结合后，以不依赖内质网的、特定细胞类型的方式刺激或抑制细胞增殖。G-1受体激动剂的发现为阐明(1-[4-(6-bromobenzo[1，3]dioxol-5yl)-3a，4，5，9b-tetrahydro-3H-cyclopenta[c]quinolin-8-yl]-ethanone)在细胞生长调控中的生物学意义提供了难得的机会，尤其是在表达ER1和/或ER2的细胞中。利用G-1，并经siRNA敲除实验证实，我们最近证实了G-1对培养的AD和ADT耐药的前列腺癌细胞的生长有很强的抑制作用。还能抑制PC-3裸鼠移植瘤的生长。在PCa临床标本中，GPR30mRNA的表达与其周围正常组织相比有降低的趋势，但不同的PCa组织中GPR30mRNA的表达程度有很大差异。去甲基化药物5-氮-2‘-脱氧胞苷、曲索他汀A、HDACi或ADT处理后，Pca细胞GPR30表达增加。基于这些新的发现，我们假设GPR30信号通过其特定的配体G-1激活，单独或与去甲基化药物、组蛋白脱乙酰酶抑制剂(HDACi)或雄激素消融联合使用，是一种有效的抗PCa治疗方法，GPR30在PCa中具有预后价值。为了检验这一假设，本文提出了三个目标。目的：在体内外研究GPR30在G-1诱导的AD和ADT耐药的前列腺癌细胞生长抑制/杀伤中的作用。目的：确定DNA甲基化、组蛋白去乙酰化或雄激素抑制是否参与GPR30表达的调节，并比较G-1单独或与其中一种药物联合抑制前列腺癌生长的效果。目的：评价GPR30在前列腺癌中的表达及其预后价值。该项目将首次提供证据支持GPR-30作为一种新的前列腺癌治疗靶点，并为未来基于GPR30的前列腺癌治疗方法的发展奠定基础。 公共卫生相关性： 前列腺癌影响着六分之一的男性一生，并对退伍军人的医疗保健产生重大影响。这项研究的主旨是基于我们对G偶联蛋白受体GPR30的理解设计一种新的前列腺癌疗法。这项研究与早期和晚期前列腺癌的治疗有关，并可能建立GPR30作为前列腺癌的预后标志物。

DESCRIPTION (provided by applicant): Prostate cancer (PCa) has major impacts on veterans' health care and its incidence will continue to grow as the population ages. Despite continual progress in the development of PCa therapies, patients with androgen-deprivation-therapy (ADT)-resistant disease have limited options. Perenteral estrogens with reduced cardiovascular toxicities have shown promise in PCa treatment in recent years. An orphan G protein-coupled receptor (GPR30) with high-affinity and low-capacity binding to estrogens was identified at both the plasma membrane and the endoplasmic reticulum. This receptor is believed to be the key mediator of the non-genomic action of estrogens. Upon its binding to ligand, GPR30 either stimulates or inhibits cell proliferation in an ER- independent, cell type-specific manner. The identificaion of G-1 (1-[4-(6-bromobenzo[1,3]dioxol-5yl)-3a,4,5,9b- tetrahydro-3H-cyclopenta[c]quinolin-8-yl]-ethanone) as a GPR30-selective agonist with no estrogenic activity provides a unique opportunity to elucidate the biological significance of GPR30 in cell growth regulation, especially in cells that express ER1 and/or ER2. Using G-1, and confirmed by siRNA knockdown experiments, we recently demonstrated strong inhibitory effects of G-1 on the growth of AD and ADT-resistant PCa cells in culture. It also inhibited PC-3 xenograft growth in nude mice. A trend of reduction of GPR30 mRNA expression was observed in PCa clinical specimens when compared to their adjacent normal tissues although the degree of expression varies a great deal among PCa specimens. Treatment of PCa cells with 5-aza-2'-deoxycytidine, a demethylating agent, tricostatinA, a HDACi, or an ADT increased GPR30 expression. Based on these novel findings, we here hypothesize that activation of GPR30 signaling via its specific ligand G-1, either alone or in combination with a demethylating agent, a histone deacetylase inhibitor (HDACi), or androgen ablation, is an effective anti-PCa therapy, and that GPR30 has prognostic value in PCa. Three aims are proposed to test this hypothesis. Objective 1: Establish the role of GPR30 in G-1-induced growth inhibition/cell kill in AD and ADT- resistant PCa cells under in vitro and in vivo settings. Objective 2: Determine whether DNA methylation, histone deacetylation, or androgen repression are involved in the regulation of GPR30 expression and compare the efficacies of G-1, alone or in combination with one of these agents in curbing PCa growth. Objective 3: Evaluate the prognostic value of GPR30 expression in PCa. This project will provide the first evidence in support of GPR-30 as a novel PCa therapeutic target and lay down a foundation for future development of GPR30-based therapies for PCa. PUBLIC HEALTH RELEVANCE: Prostate cancer affects one out of six men in their life time and has significant impacts on veterans' health care. The main thrust of this research is to design a new class of prostate cancer therapies based on our understanding of a G-coupled protein receptor known as GPR30. The research is relevant to the treatment of early stage and advanced stage prostate cancer and may establish GPR30 as a prognostic marker for prostate cancer.