Role of Rho GDP dissociation inhibitors in androgen signaling in prostate cancer

描述(由申请人提供)： 项目概述Rho GDP解离抑制剂在前列腺癌雄激素信号转导中的作用关键词(仅网格项；至少三个)前列腺癌，雄激素受体，RhoGDI，去势抵抗，增殖研究目的简述(不使用续页)播散性前列腺癌(CAP)的治疗是雄激素的停用。然而，CAP最终在雄激素非依赖性或去势抵抗状态下继续生长。人们一直致力于了解去势耐药前列腺癌(CRPC)的发生和发展机制。雄激素受体(AR)似乎在CRPC的发生发展中起着核心作用。我们通过蛋白质二维凝胶分析结合蛋白质序列分析，发现了一个新的信号分子RhoGDI1，它在前列腺癌中表达下调，并且在前列腺癌向CRPC发展过程中起着关键作用。前列腺癌组织中RhoGDI1的表达水平低于良性前列腺组织。RhoGDI1的过表达抑制了耐去势的前列腺癌细胞的生长，并导致逆转到雄激素敏感阶段，而RhoGDI1的下调在雄激素缺乏的条件下促进了雄激素敏感的前列腺癌细胞的生长。此外，RhoGDI1通过与AR的相互作用抑制AR的表达和AR的激活。基于这些数据，我们假设RhoGDI1表达的缺失通过激活AR信号通路促进前列腺癌的发生和发展。在这个方案中，我们将研究RhoGDI1的功能，并阐明在前列腺癌进展到去势抵抗过程中RhoGDI1与雄激素信号相互作用的分子途径。本研究的具体目的是：1.检测RhoGDI1对体外培养的前列腺癌细胞雄激素反应性的影响。我们将RhoGDI1在雄激素反应性的人前列腺癌LNCaP和LAPC-4细胞中的表达下调，并在雄激素非依赖性的C4-2和LNCaP-IL6+细胞中过表达RhoGDI1，以确定RhoGDI对细胞生长和雄激素反应的影响。为了研究RhoGDI1在体内前列腺癌发生和发展中的作用，我们将对前列腺癌细胞中RhoGDI1的水平进行操作，并检测这种操作对完整和去势的雄性无性腺小鼠肿瘤的形成和发展以及对雄激素诱导基因(如PSA)表达的影响。为了确定RhoGDI1如何与AR信号相互作用，我们将精确定位AR和RhoGDI1相互作用的位置。我们将检测RhoGDI1是否影响AR的转录起始、蛋白质周转和核转位以及AR的DNA结合活性。RhoGDI1对雄激素反应基因启动子的募集将通过染色质免疫沉淀(CHIP)检测。对退伍军人医疗保健的潜在影响：前列腺癌现在超过肺癌，成为美国男性最常见的确诊癌症，也是同一人群中癌症死亡的第二大原因。很大一部分前列腺癌患者通过雄激素剥夺疗法获得了成功的治疗。然而，由于获得了抗去势肿瘤细胞的生长，几乎所有的患者都会复发。不幸的是，目前还没有有效的治疗方法来治疗男性的去势抵抗前列腺癌。本提案直接涉及抗去势前列腺癌演变的机制，并确定了参与这一过程的关键因素。因此，该项目的目标是耐阉割的前列腺癌，这是男性退伍军人中的一个非常严重的健康问题。我们重要的机制和临床前研究将为基于去势的机制辅助疗法的发展奠定基础，这可能会导致比单独去势更有效的干预。退伍军人事务部表格10-1313-2退伍军人事务部表格10-1313包装第2页1990年6月(R) 公共卫生相关性： 项目简介前列腺癌是美国男性最常见的诊断癌症，也是癌症死亡的第二大原因。虽然前列腺癌最初对雄激素剥夺治疗有反应，但几乎所有患者都会复发到去势抵抗前列腺癌(CRPC)。不幸的是，目前还没有有效的治疗方法来治疗男性慢性前列腺癌。本提案直接涉及CRPC这一演变的机制，并确定了这一过程中涉及的一个新因素。我们的假设是RhoGDI1表达的缺失促进了前列腺癌的发生和发展。在这项提案中，我们将研究RhoGDI1在前列腺癌进展到去势抵抗过程中的作用。因此，该项目的目标是CRPC，这是男性退伍军人中的一个非常严重的健康问题。这项研究的完成将极大地提高目前对CRPC机制的理解。

DESCRIPTION (provided by applicant): SUMMARY DESCRIPTION OF PROJECT Role of Rho GDP dissociation inhibitors in androgen signaling in prostate cancer KEYWORDS (MeSH terms only; minimum three) Prostate cancer, androgen receptor, RhoGDI, castration-resistance, proliferation BRIEF STATEMENT OF RESEARCH OBJECTIVES (Do not use continuation sheets) Treatment for disseminated prostate cancer (CaP) is the withdrawal of androgens. However, CaP eventually continues to grow in an androgen-independent or castration-resistant state. Great effort has focused on understanding the mechanisms involved in the development and progression of castration-resistant prostate cancer (CRPC). Androgen receptor (AR) appears to play a central role in the development and progression of CRPC. We have identified a novel signaling molecule namely RhoGDI1, using 2-D gel analysis of protein profile combined with protein sequencing, that is downregulated in prostate cancer and its downregulation plays critical role during prostate cancer progression to CRPC. The levels of RhoGDI1 expression were decreased in prostate cancer tissues compared to benign prostate tissues. Overexpression of RhoGDI1 inhibited the growth of castration-resistant prostate cancer cells and caused a reversal to an androgen-sensitive stage, while downregulation of RhoGDI1 enhanced androgen-sensitive prostate cancer cell growth in androgen-deprived conditions. Furthermore, RhoGDI1 suppressed AR expression and AR activation via interaction with AR. Based on these data, we hypothesize that loss of RhoGDI1 expression promotes the development and progression of prostate cancer by activating the AR signaling pathway. In this proposal, we will study the function of RhoGDI1 and elucidate the molecular pathways of RhoGDI1 interaction with androgen signaling during prostate cancer progression to castration-resistance. The specific aims are: I. To examine the effects of RhoGDI1 on androgen responsiveness of prostate cancer cells in vitro We will knockdown RhoGDI1 expression in androgen-responsive LNCaP and LAPC-4 human prostate cancer cell lines, and overexpress RhoGDI1 in androgen-independent C4-2 and LNCaP-IL6+ cells to determine the effects of RhoGDI on cell growth and response to androgens. II. To examine the effects of RhoGDI1 on the development and progression of prostate cancer in vivo We will manipulate the levels of RhoGDI1 in prostate cancer cells and examine the effects of such manipulation on the formation and progression of tumors, as well as on the expression of androgen-inducible genes such as PSA in intact and castrated male athymic mice. III. To determine how RhoGDI1 interacts with AR signaling We will pinpoint the site of AR and RhoGDI1 interaction. We will examine if RhoGDI1 affects AR mRNA transcriptional initiation, protein turnover and nuclear translocation and DNA binding activity of AR. RhoGDI1 recruitment to the promoters of androgen responsive genes will be examined by chromatin immunoprecipitation (ChIP) assays. Potential impact on Veterans health care: Prostate cancer now exceeds lung cancer as the most commonly diagnosed cancer in the United States men, and it is the second leading cause of cancer death in that same population. A very large portion of men with prostate cancer are treated successfully with androgen deprivation therapy. However, virtually all patients will relapse due to acquisition of the growth of castration resistant tumor cells. Unfortunately, there is currently no effective treatment for men with castration resistant prostate cancer. The present proposal directly deals with the mechanisms of this evolution of castration resistant prostate cancer and has identified a critical factor involved in this process. Thus, this project targets castration resistant prostate cancer, a very significant health problem among male veterans. Our important mechanistic and pre-clinical studies will serve as the foundation for development of a mechanism based castration-adjunctive therapy, which may lead to a more effective intervention than castration alone. VA FORM 10-1313-2 Page 2 of VA Form 10-1313 package JUN 1990(R) PUBLIC HEALTH RELEVANCE: Project Narrative Prostate cancer is the most commonly diagnosed cancer and the second leading cause of cancer death in the United States men. Although prostate cancer initially response to androgen deprivation therapy, virtually all patients will relapse to castration resistant prostate cancer (CRPC). Unfortunately, there is currently no effective treatment for men with CRPC. The present proposal directly deals with the mechanisms of this evolution of CRPC and has identified a novel factor involved in this process. Our hypothesis is that loss of RhoGDI1 expression promotes the development and progression of prostate cancer. In this proposal, we will study the role of RhoGDI1 during prostate cancer progression to castration-resistance. Thus, this project targets CRPC, a very significant health problem among male veterans. Completion of this study will significantly enhance current understanding of the mechanism of CRPC.