Regulator of G-protein Signaling (RGS) Proteins in Prostate Cancer

描述(申请人提供)：G蛋白偶联受体(GPCR)信号异常可导致包括癌症在内的许多人类疾病。G蛋白信号转导调节蛋白(RGS)抑制GPCRs信号转导。这一应用的长期目标是阐明RGS蛋白在肿瘤发生中的作用。前列腺癌是男性最常见的癌症，前列腺癌获得雄激素非依赖性是前列腺癌进展的关键问题。一些证据表明，雄激素非依赖性激活雄激素受体(AR)是其潜在机制之一。最近的研究表明，激素通过G蛋白偶联受体(GPCRs)作用于雄激素非依赖性AR。我们最近报道了RGS超家族成员RGS2通过GPCR信号选择性地抑制前列腺癌细胞中雄激素非依赖性AR的激活。有趣的是，在已建立的前列腺癌细胞系中，RGS2蛋白的表达与雄激素非依赖性细胞的增殖呈负相关。此外，与正常前列腺癌组织相比，人类前列腺癌样本的RGS2水平显著降低。因此，我们假设RGS2是一种新的AR信号调节因子，它的抑制是前列腺癌发生和发展的重要一步。 具体目的：1.评估RGS2抑制在前列腺癌细胞中的生物学意义。2.探讨RGS2抑制雄激素非依赖性前列腺癌生长的分子机制。3.阐明前列腺癌中RGS2抑制的机制。 研究设计与方法：我们将首先检测RGS2表达的改变对前列腺癌细胞在培养和去势裸鼠体内雄激素非依赖性生长的影响。然后，我们将确定RGS2的氨基酸对其选择性地抑制前列腺癌细胞中雄激素非依赖性AR激活和细胞生长至关重要，并确定负责RGS2调节它的AR结构域。最后，我们将结合甲基化特异性的聚合酶链式反应和免疫组织化学分析来研究RGS2基因的甲基化是否导致前列腺癌中RGS2的抑制。然后将评估使用RGS2表达和/或RGS2甲基化状态作为前列腺癌诊断和预后的新标记物的可行性。除了甲基化，我们还将探索基因改变或组蛋白修饰是否有助于前列腺癌中RGS2的抑制。 有关RGS2在调节前列腺癌进展中的生物学重要性的信息直接与理解前列腺癌的生物学相关。拟议研究的完成不仅将为前列腺癌的进展提供一个潜在的诊断和预后标志，而且还将使治疗前列腺癌的新药开发成为可能。

DESCRIPTION (provided by applicant): Aberrant G protein-coupled receptor (GPCR) signaling causes many human diseases including cancer. Regulator of G-protein signaling (RGS) proteins inhibit GPCR signaling. The long-term goal of this application is to elucidate the roles of RGS proteins in tumorigenesis. Prostate cancer is the most common cancer in men and acquisition of androgen independence by prostate cancer is the key problem of prostate cancer progression. Several lines of evidence suggest that androgen-independent activation of androgen receptor (AR) is one of underlying mechanisms. Recent studies demonstrate that hormones acting through G protein-coupled receptors (GPCRs) cause androgen-independent AR activation. We recently reported that RGS2, a member of RGS superfamily, selectively inhibits androgen-independent AR activation by GPCR signaling in prostate cancer cells. Interestingly, RGS2 protein expression was inversely correlated with the androgen-independent cell proliferation in established prostate cancer cell lines. In addition, human prostate cancer specimens had significantly lower levels of RGS2 compared to normal prostate tissues. Thus, we hypothesize that RGS2 functions as a novel regulator of AR signaling and its repression is an important step in prostate tumorigenesis and progression. Specific Aims: 1. To assess the biological importance of RGS2 repression in prostate cancer cells. 2. To determine the molecular mechanism underlying RGS2-mediated inhibition of androgen-independent prostate cancer growth. 3. To elucidate the mechanism underlying RGS2 repression in prostate cancer. Research Design and Methods: We will first examine the effects of altering RGS2 expression on the androgen-independent growth of prostate cancer cells in culture and in castrated athymic nude mice. We will then pinpoint the amino acids of RGS2 critical for its selective inhibition of androgen-independent AR activation and cell growth in prostate cancer cells and identify the AR domains responsible for its regulation by RGS2. Finally, we will combine methylation-specific PCR and immunohistochemistry analysis to investigate whether methylation of the RGS2 gene is responsible for RGS2 repression in prostate cancer. The feasibility of using RGS2 expression and/or RGS2 methylation status as a novel marker for diagnosis and prognosis of prostate cancer will then be evaluated. In addition to methylation, we will also explore whether genetic alterations or histone modifications contribute to RGS2 repression in prostate cancer. Information on the biological importance of RGS2 in the regulation of prostate cancer progression is directly relevant to understanding the biology of prostate cancer. Completion of the proposed studies will not only provide a potential diagnostic and prognosis marker for prostate cancer progression but will also allow the development of novel drugs for the treatment of prostate cancers.