Towards selective androgen deprivation by targeting androgen activation of SRF

描述(申请人提供)：尽管雄激素受体(AR)在前列腺癌(CAP)进展中起着核心作用，但对雄激素控制推动CAP进展的细胞过程的具体分子机制的了解在很大程度上仍然难以捉摸。缺乏这种知识是一个重要的问题，因为如果没有这种知识，就不可能开发出专门针对致命表型下的雄激素依赖事件的新的治疗方法。长期目标是了解雄激素控制帽细胞中临床相关基因表达的机制(S)如何被操纵用于治疗干预。目的是确定雄激素控制血清反应因子(SRF)活性的分子机制(S)以及这些机制与CAP进展的相关性。中心假说是，雄激素调节基因的SRF反应亚集通过RhoA信号轴和RhoA效应器PKN1和CIT的雄激素激活而导致攻击性CAP表型。这一假设是基于申请人实验室所做的初步工作而提出的。拟议研究的基本原理是，一旦了解了雄激素调节SRF在CAP中的作用是如何发生的，选择与疾病进展相关的雄激素作用的靶向将是可能的。通过追求3个具体目标来检验中心假设：1)确定RhoA、PKN1和CIT在SRF靶基因的雄激素调节中的作用；2)确定雄激素调节基因的SRF反应亚集在帽细胞运动和侵袭行为中的临床前作用；以及3)确定RhoA、PKN1和CIT依赖的雄激素反应SRF作用的临床相关性。目的1采用定制基因表达分析方法，研究RhoA、PKN1和CIT在SRF靶基因雄激素调控中的作用，以及PKN1和CIT向SRF传递雄激素调控的方式。目的2利用临床前模型确定SRF靶基因，PKN1和CIT作为靶基因以削弱CAP细胞的侵袭性。目的3结合计算机分析和组织芯片分析来确定PKN1、CIT和SRF效应基因与CAP进展的相关性。这项拟议的研究具有创新性，因为它专注于一种完全不同的方法来靶向CAP中的雄激素作用：解开并靶向AR下游的雄激素依赖的信号通路，该通路控制与CAP进展相关的基因的表达。这一贡献意义重大，因为这是一系列研究的第一步，预计将导致开发新的治疗模式，这些模式专门针对雄激素介导的致死帽表型下的基因表达。就预期结果而言，拟议的研究将确定SRF依赖的雄激素作用机制导致攻击性CAP表型的分子机制。这些结果将产生重要的积极影响，因为它们将从根本上促进对雄激素在CAP中作用的了解，并特别为CAP特异性治疗提供新的靶点。

DESCRIPTION (provided by applicant): Despite the central role of androgen receptor (AR) in prostate cancer (CaP) progression, insights into the specific molecular mechanisms by which androgens control the cellular processes that drive CaP progression remain largely elusive. Lack of this knowledge is an important problem, because without it, development of novel therapeutic approaches that target specifically androgen-dependent events underlying the lethal phenotype is unlikely. The long-term goal is to understand how the mechanism(s) by which androgens control clinically relevant gene expression in CaP cells can be manipulated for therapeutic intervention. The objective is to determine the molecular mechanism(s) by which androgens control activity of Serum Response Factor (SRF) and the relevance of these mechanisms for CaP progression. The central hypothesis is that the SRF- responsive subset of androgen-regulated genes is responsible for the aggressive CaP phenotype via androgen activation of the RhoA signaling axis and the RhoA effectors PKN1 and CIT. This hypothesis is formulated based on preliminary work produced in the applicant's laboratory. The rationale for the proposed studies is that, once it is understood how androgen regulation of SRF action in CaP occurs, select targeting of androgen action that is relevant to disease progression will be possible. The central hypothesis is tested by pursuing 3 specific aims: 1) define the contribution of RhoA, PKN1 and CIT in androgen regulation of SRF target genes; 2) determine the preclinical role of the SRF-responsive subset of androgen-regulated genes in CaP cell motility and invasive behavior; and 3) determine the clinical relevance of RhoA-, PKN1-, and CIT-dependent androgen- responsive SRF action. Aim 1 uses a custom gene expression assay to determine the contribution of RhoA, PKN1 and CIT to androgen regulation of SRF target genes, and the manner in which PKN1 and CIT convey androgen control to SRF is established. Aim 2 uses preclinical models to identify SRF target genes, PKN1 and CIT as targets to impair CaP cell invasiveness. Aim 3 uses a combination of in silico analysis and tissue microarray analyses to determine the relevance of PKN1, CIT and SRF effector genes for CaP progression. The proposed research is innovative because it focuses on an entirely different approach to target androgen action in CaP: unraveling and targeting an androgen-dependent signaling pathway downstream of AR that controls the expression of genes that are relevant for CaP progression. This contribution is significant because is it the first step in a continuum of research that is expected to lead to the development of novel treatment modalities that target specifically androgen-mediated gene expression that underlies the lethal CaP phenotype. With respect to expected outcomes, the proposed studies will identify the molecular mechanisms by which the SRF-dependent mechanism of androgen action gives rise to the aggressive CaP phenotype. These results will have an important positive impact because they will fundamentally advance knowledge about androgen action in CaP, in general, and provide new targets for CaP-specific therapy, specifically.