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

描述（由申请人提供）：异常G蛋白偶联受体（GPCR）信号传导导致许多人类疾病，包括癌症。G蛋白信号传导调节因子（Regulator of G-protein signaling，RGS）蛋白抑制GPCR信号传导。本申请的长期目标是阐明RGS蛋白在肿瘤发生中的作用。前列腺癌是男性最常见的恶性肿瘤，前列腺癌雄激素非依赖性的获得是前列腺癌进展的关键问题。许多证据表明，雄激素受体（AR）的雄激素非依赖性激活是其潜在机制之一。最近的研究表明，激素通过G蛋白偶联受体（GPCRs）作用，导致雄激素非依赖性AR激活。我们最近报道，RGS 2，RGS超家族的成员，选择性地抑制雄激素非依赖性AR激活的GPCR信号在前列腺癌细胞。有趣的是，RGS 2蛋白表达与已建立的前列腺癌细胞系中的雄激素非依赖性细胞增殖呈负相关。此外，与正常前列腺组织相比，人前列腺癌标本具有显著较低水平的RGS 2。因此，我们假设RGS 2作为AR信号传导的新型调节剂发挥作用，并且其抑制是前列腺肿瘤发生和发展的重要步骤。 具体目标：1。评估RGS 2抑制在前列腺癌细胞中的生物学重要性。2.确定RGS 2介导的雄激素非依赖性前列腺癌生长抑制的分子机制。3.阐明RGS 2在前列腺癌中的抑制机制。 研究设计和方法：我们将首先研究改变RGS 2表达对培养和去势无胸腺裸鼠中前列腺癌细胞雄激素非依赖性生长的影响。然后，我们将确定RGS 2的氨基酸，这些氨基酸对于其选择性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RGS 2调节的AR结构域。最后，我们将结合联合收割机甲基化特异性PCR和免疫组化分析来研究RGS 2基因的甲基化是否是前列腺癌中RGS 2抑制的原因。然后将评估使用RGS 2表达和/或RGS 2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，我们还将探索遗传改变或组蛋白修饰是否有助于前列腺癌中的RGS 2抑制。 RGS 2在调节前列腺癌进展中的生物学重要性的信息与理解前列腺癌的生物学直接相关。完成拟议的研究不仅将为前列腺癌进展提供潜在的诊断和预后标志物，而且还将允许开发用于治疗前列腺癌的新药。

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.