The Role of NOV (CCN3) in Prostate Cancer Progression

描述（由申请人提供）：前列腺癌（PCa）是美国男性中最常见的非皮肤癌。虽然器官受限的前列腺癌可以通过手术和放射治疗有效根除，但转移性疾病基本上是无法治愈的。雄激素受体（AR）介导的雄激素信号是前列腺癌发生和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，在晚期去势抵抗性PCa （CRPC）中，AR在低雄激素环境中被激活，而不是不敏感，从而导致去势抵抗。因此，理解和靶向AR通路仍然是PCa研究的核心挑战。虽然对AR信号的研究已经进行了几十年，但由于过去主要关注由AR诱导的基因，对AR信号的理解并不完全。有趣的是，最近的研究，包括我们的研究，已经开始表明AR也是一种全球作用的转录抑制因子。此外，我们的数据表明，这种抑制是由多梳群蛋白EZH2介导的，并抑制靶基因周围的染色质重塑。然而，需要一个模型基因来代表AR的这种创新作用，以进一步描述AR介导的抑制的机制细节，最重要的是，了解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微阵列数据的meta分析，我们将NOV （CCN3）作为首选候选基因。我们的初步数据表明，NOV在前列腺癌中是一个重要的新基因。它被AR和EZH2抑制，在晚期前列腺癌中明显下调。功能分析表明，NOV抑制前列腺癌进展，其功能丧失驱动去势抵抗。因此，我们假设AR通过抑制染色质重塑直接抑制NOV，并在PCa进展中发挥重要作用。为了解决这一假设，提出了三个具体目标。在Aim 1中，我们将确定前列腺癌（包括患者样本）中的雄激素调节和NOV表达。在Aim 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基因启动子和/或增强子结合，绘制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，从而抑制基因。目的3将通过细胞系模型和裸鼠研究NOV在调节前列腺癌增殖、迁移、侵袭/转移和去势抵抗中的功能作用。

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.