The Role of NOV (CCN3) in Prostate Cancer Progression

描述(申请人提供)：前列腺癌(PCa)是美国男性最常见的非皮肤癌。虽然器官受限的前列腺癌可以通过手术和放射治疗有效地根除，但转移性疾病基本上是无法治愈的。雄激素信号通过雄激素受体(AR)介导，是前列腺癌发生发展的重要途径之一。因此，激素剥夺已成为转移性前列腺癌的标准一线治疗方法。有趣的是，在后期的去势抵抗PCA(CRPC)中，AR在低雄激素环境中被激活，而不是不敏感，因此与去势抵抗有关。因此，理解和靶向AR通路仍然是PCA研究的核心挑战。虽然AR信号已经被研究了几十年，但由于过去主要集中在AR诱导的基因上，人们对AR信号的了解还不完全。有趣的是，最近的研究，包括我们的研究，已经开始显示AR也是一个全球性的转录抑制因子。此外，我们的数据表明，这种抑制是由多梳组蛋白EZH2和靶基因周围抑制染色质重塑介导的。然而，需要一个代表AR这种创新作用的模型基因来进一步描述AR介导的抑制的机制细节，最重要的是，认识这种抑制的功能相关性和治疗重要性。通过对雄激素调控表达芯片数据的荟萃分析，我们提名NOV(CCN3)为首选候选基因。我们的初步数据表明，nov是一个在前列腺癌中具有重要作用的新基因。它被AR和EZH2抑制，在晚期PCa中显著下调。功能分析表明，NOV抑制了PCa的进展，其功能丧失驱动了去势抵抗。因此，我们假设NOV是通过抑制染色质重塑而被AR直接抑制的，并且在PCa的进展中起着重要作用。为了解决这一假设，本文提出了三个具体目标。在目标1中，我们将确定雄激素调节和NOV在前列腺癌中的表达，包括患者样本。在目标2中，我们将研究AR如何抑制前列腺癌细胞中NOV的表达。我们将确定AR是否直接与nov基因的启动子和/或增强子结合，映射基因周围的染色质变化，并检查EZH2是否/如何对这些变化做出反应，从而进行基因抑制。目的研究NOV对PCa增殖、迁移、侵袭/转移和去势抵抗的调节作用。

DESCRIPTION (provided by applicant): Prostate cancer (PCa) is the most commonly diagnosed non-skin cancer in American men. While organ-confined PCa can be effectively eradicated through surgical and radiation therapies, metastatic disease is essentially incurable. Androgen signaling mediated through the androgen receptor (AR) is one of the most important pathways in PCa initiation and progression. Hormone-deprivation has thus been the standard, first-line treatment for metastatic PCa. Interestingly, in the late-stage castration-resistant PCa (CRPC), AR has become activated, rather than insensitive, in a low androgen environment, thus being responsible for castration resistance. Therefore, understanding and targeting AR pathway remains a central challenge in PCa research. While AR signaling has been studied for decades, it is incompletely understood with past focus largely on genes induced by the AR. Interestingly, recent studies, including ours, have started to show AR also as a globally acting transcriptional repressor. Further, our data suggest that this repression is mediated by the polycomb group protein EZH2 and repressive chromatin remodeling around the target genes. However, a model gene that is representative of this innovative role of AR is needed to further delineate the mechanistic details of AR-mediated repression and, most importantly, to appreciate the functional relevance and therapeutic importance of this repression. Through meta-analysis of androgen-regulated expression microarray data, we nominated NOV (CCN3) as a top candidate. Our preliminary data suggest that NOV is a novel gene of great importance in PCa. It is inhibited by AR and EZH2 and is markedly down-regulated in advanced PCa. Functional analysis suggests that NOV inhibits PCa progression and its loss-of-function drives castration resistance. We thus hypothesize that NOV is directly suppressed by AR through repressive chromatin remodeling and plays essential roles in PCa progression. To address this hypothesis, three specific aims are proposed. In Aim 1, we will determine androgen regulation and NOV expression in prostate cancer, including patient samples. In Aim 2, we will examine how AR inhibits NOV expression in prostate cancer cells. We will determine if AR directly binds to the NOV gene promoter and/or enhancer, map chromatin changes around the gene, and examine whether/how EZH2 is response for these changes and thus gene repression. Aim 3 will investigate the functional role of NOV in regulating PCa proliferation, migration, invasion/metastasis, and castration resistance using cell line models and nude mice.