Regulation of androgen receptor signaling in prostate cancer by protein arginine methylation

项目摘要 前列腺癌是美国男性癌症死亡的第二大常见原因。而 早期前列腺癌通常对激素治疗有反应，一部分发展为不可治愈的“去势”， 耐药状态（CRPC），其对标准激素疗法具有耐药性。CRPC的定义性分子特征 是雄激素受体（AR）信号的重新激活，表明AR仍然是前列腺癌的核心 疾病状态之间的发病机制。因此，消融AR信号传导的新方法可以激发新的治疗方法 CRPC的战略。通过基因组规模的CRISPR/Cas9筛选，我们鉴定了精氨酸蛋白， 甲基转移酶1和5（PRMT 1/PRMT 5）作为AR途径的新型调节剂。PRMT 1和PRMT 5 调节多种生物过程，包括AR信号传导，通过翻译后修饰 精氨酸残基上的底物蛋白质。由于PRMT 1和PRMT 5的小分子抑制剂最近已被发现， 进入临床开发，该途径也可以在患者中进行治疗调节。 该提议验证了PRMT可能在调节AR驱动的转录中具有特定作用的假设。 通过对AR和/或其辅因子的直接作用来进行程序，并且与PRMT抑制剂的联合治疗 直接AR拮抗剂可能是晚期前列腺癌的有效治疗策略。目标1： 将剖析PRMT 1和PRMT 5调节AR信号的分子机制。具体来说，我们将 比较PRMT 1和PRMT 5在各种细胞环境中对AR信号传导的影响。然后我们将 研究这些PRMT在调节不同节点的AR信号传导中的作用，包括组蛋白修饰， 染色质结构、AR共调节因子的修饰和AR本身的修饰。在目标2中，我们将 建立PRMT 1和/或PRMT 5抑制剂与AR拮抗剂组合在 体外和体内前列腺癌模型。由于我们的初步数据表明PRMT 1和PRMT 5 调节AR信号，我们假设抑制这两种酶与直接抑制AR结合， 可能是治疗去势抵抗性前列腺癌和延迟去势出现的有效策略 阻力此外，先前的研究已经表明，PRMT 1和PRMT 5的组合是协同的， 在临床前体内模型中耐受良好。因此，我们将测试直接AR拮抗剂的活性， 与PRMT 1和/或PRMT 5抑制剂组合在体内患者来源的激素- 敏感性和去势抵抗性前列腺癌。最后，我们将询问PRMT 1、 PRMT 5和AR在临床注释的前列腺癌组织标本和大规模前列腺组织中的表达 癌症测序数据集。 这些实验将验证PRMT 1和PRMT 5作为前列腺癌的治疗靶点， 深入了解AR信号调节的机制。总的来说，这项工作推进了一个机制驱动的 治疗假设，有可能改善晚期前列腺癌患者的预后。

PROJECT SUMMARY Prostate cancer is the second most common cause of cancer death among men in the United States. While early-stage prostate cancers often respond to hormonal therapy, a subset progresses to an incurable “castration- resistant” state (CRPC), which is resistant to standard hormonal therapies. A defining molecular feature of CRPC is the reactivation of androgen receptor (AR) signaling, indicating that the AR remains central to prostate cancer pathogenesis across disease states. Therefore, novel means of ablating AR signaling can inspire new treatment strategies for CRPC. Through a genome-scale CRISPR/Cas9 screen, we identified the protein arginine methyltransferases 1 and 5 (PRMT1/PRMT5) as novel regulators of the AR pathway. Both PRMT1 and PRMT5 modulate diverse biological processes, including AR signaling, through post-translational modification of substrate proteins on arginine residues. As small molecule inhibitors of PRMT1 and PRMT5 have recently entered clinical development, this pathway can also be therapeutically modulated in patients. This proposal tests the hypothesis that PRMTs may have a specific role in regulating AR-driven transcriptional programs through direct effects on AR and/or its co-factors, and that combination therapy with PRMT inhibitors and direct AR antagonists may be an effective therapeutic strategy in advanced prostate cancer. In Aim 1, we will dissect the molecular mechanisms by which PRMT1 and PRMT5 regulate AR signaling. Specifically, we will compare the effects that PRMT1 and PRMT5 have on AR signaling in various cellular contexts. We will then investigate roles for these PRMTs in modulating AR signaling at various nodes, including histone modification, chromatin architecture, modification of AR co-regulators, and modification of the AR itself. In Aim 2, we will establish the therapeutic potential of combining PRMT1 and/or PRMT5 inhibitors with an AR antagonist in in vitro and in vivo prostate cancer models. Since our preliminary data indicate that both PRMT1 and PRMT5 modulate AR signaling, we hypothesize that inhibiting both enzymes in combination with direct inhibition of AR may be an effective strategy to treat castration-resistant prostate cancer and to delay the emergence of castration resistance. Moreover, prior studies have shown that the combination of PRMT1 and PRMT5 is synergistic and well-tolerated in preclinical in vivo models. We will therefore test the activity of direct AR antagonists in combination with PRMT1 and/or PRMT5 inhibitors in in vivo patient-derived xenograft models of hormone- sensitive and castration-resistant prostate cancer. Finally, we will interrogate the relationship between PRMT1, PRMT5, and AR expression in clinically-annotated prostate cancer tissue specimens and in large-scale prostate cancer sequencing datasets. These experiments will validate PRMT1 and PRMT5 as therapeutic targets in prostate cancer and will lend insight into the mechanisms by which AR signaling is regulated. Overall, this work advances a mechanism-driven therapeutic hypothesis with the potential to improve outcomes for patients with advanced prostate cancer.