AR Gene Rearrangements and AR Signaling in Prostate Cancer

描述（由申请人提供）：前列腺癌是最常见的男性癌症，也是男性癌症死亡的第二大原因。如果主要治疗方式不能控制疾病，抑制雄激素受体（AR）活性是晚期前列腺癌患者的有效治疗方法。然而，患者对ar靶向治疗的反应持续时间是可变的，所有患者最终都会产生耐药性，并进展为与发病率和死亡相关的去势抵抗形式的疾病。去势抵抗性前列腺癌（CRPC）的一个重要特征是尽管循环雄激素水平降低，但AR转录活性的异常再激活。这一知识导致了新疗法的发展，这些疗法抑制了支持CRPC中AR残余转录活性的机制。然而，耐药性仍然是这些新的ar靶向药物的主要限制。由于这一领域需要新的认识和创新，本研究的长期目标是确定尽管进行了AR靶向治疗，但仍能支持持续AR转录活性的机制，并制定更有效的治疗和管理CRPC患者的策略。推动上述研究的核心发现是AR mRNA剪接改变，导致cooh末端截断的AR变体（AR- v）蛋白在完全没有雄激素刺激的情况下实现构成性转录活性。这些AR- v的合成已成为临床CRPC进展的一个重要方面，但AR剪接改变的机制在很大程度上是未知的。本研究的总体目标是了解新发现的AR基因重排在驱动CRPC中AR剪接模式改变和AR- v高效合成中的作用。为实现这一目标，提出了三个具体目标。在Aim 1中，将使用定制的下一代DNA和RNA测序工具来确定CRPC患者组织中AR基因重排和剪接改变的谱。在Aim 2中，可编程核酸酶技术将用于实验性地设计前列腺癌基因组中特定位点的AR基因重排。这些基因组工程细胞将被研究，以建立AR基因结构变化、异常AR mRNA剪接模式、AR- v合成和CRPC表型之间的联系。在Aim 3中，AR基因重排将被评估为检测异质肿瘤中AR- v驱动的CRPC细胞群的新生物标志物，预测对AR靶向治疗的反应，并监测AR靶向治疗期间耐药性的发展。这些研究的成功将确立一类全新的AR基因改变在前列腺癌进展中的作用，并为评估前列腺癌细胞中AR基因状态提供新的方法。在这项提议中开发的知识和资源对于开发基于个体患者独特的AR基因结构的前列腺癌新治疗方案非常重要。

DESCRIPTION (provided by applicant): Prostate cancer is the most frequently diagnosed male cancer and second leading cause of male cancer death. If primary treatment modalities are not capable of controlling the disease, inhibiting androgen receptor (AR) activity is an effective treatment for advanced prostate cancer patients. However, the duration of patient responses to AR-targeted therapy is variable, and all patients will ultimately develop resistance and progress to a castration-resistant form of the disease associated with morbidity and death. One important feature of castration-resistant prostate cancer (CRPC) is aberrant re-activation of AR transcriptional activity despite reduced levels of circulating androgens. This knowledge has led to the development of new therapies that inhibit mechanisms supporting residual transcriptional activity of the AR in CRPC. However, resistance remains a major limitation for these new AR-targeted agents. Because of the major need for new understanding and innovation in this area, the long-term objectives of this research are to determine the mechanisms that can support persistent AR transcriptional activity despite AR-targeted therapy, and to develop more effective strategies for treating and managing patients with CRPC. The central discovery driving the proposed studies is altered AR mRNA splicing, giving rise to COOH-terminally truncated AR variant (AR-V) proteins that achieve constitutive transcriptional activity in the complete absence of androgen stimulus. Synthesis of these AR-Vs has emerged as an important aspect of clinical CRPC progression, but mechanisms responsible for alterations in AR splicing are largely unknown. The overarching goal of this proposal is to understand the role of newly-discovered AR gene rearrangements in driving altered AR splicing patterns and efficient AR-V synthesis in CRPC. To achieve this goal, three specific aims are proposed. In Aim 1, an arsenal of customized next-generation DNA and RNA sequencing tools will be used to determine the spectrum of AR gene rearrangements and splicing alterations in tissues from patients with CRPC. In Aim 2, programmable nuclease technology will be used to experimentally engineer site-specific AR gene rearrangements in the prostate cancer genome. These genome-engineered cells will be studied to establish the links between architectural changes in the AR gene, aberrant AR mRNA splicing patterns, AR-V synthesis, and the CRPC phenotype. In Aim 3, AR gene rearrangements will be evaluated as new biomarkers for detecting AR-V driven CRPC cell populations in heterogeneous tumors, predicting responses to AR-targeted therapy, and monitoring the development of resistance during AR-targeted therapy. Success with these studies will establish the role of an entirely new class of AR gene alterations in prostate cancer progression, and provide new methods for evaluating AR gene status in prostate cancer cells. Knowledge and resources developed in this proposal will be important for developing new treatment regimens for prostate cancer based on an individual patient's unique AR gene architecture.