A novel AR degrader in castrate-resistant prostate cancer

雄激素受体(AR)在前列腺癌(PCa)的各个阶段都起着关键作用。虽然大多数患者 由于前列腺癌最初对雄激素剥夺和/或抗雄激素治疗有反应，相当一部分 患者会患上耐去势前列腺癌(CRPC)。临床研究表明，慢性前列腺癌经常是 富含缺乏配体结合结构域(LBD)的AR剪接变异体，从而在构成上具有活性 雄激素非依赖的方式和逃避抗雄激素苯扎鲁胺介导的AR抑制。 该RO1应用的目标是开发和表征有效降解的新疗法 (去除)前列腺癌中的AR蛋白。技术创新包括开发一种新的治疗平台 利用自噬靶向嵌合体(AUTOTAC)降解AR蛋白。我们成功地生成了AR- 靶向AUTOTAC，是由苯扎鲁胺(AR配体结合)组成的双功能分子 结构域抑制物)或vPC-14449(AR DNA结合结构域抑制物)作为靶结合配体，连接到 YTK-6-2作为自噬货物受体p62/Sequestosome-1/SQSTM1的配体。AR目标AUTOTAC 将靶蛋白AR带到p62，形成三元复合体。YTK-6-2诱导p62自身寡聚， 从而形成AR-p62寡聚复合体。YTK-6-2激活的p62促进AR-p62-LC3相互作用 自噬细胞膜，促进自噬小体的生物发生和AR蛋白的降解。vbl.使用 反映相关肿瘤微环境和肿瘤异质性的临床相关动物模型，我们 将测试我们的新假设，即AUTOTAC介导的AR及其变体的降解(移除)是一种更 比目前可用的治疗方法包括抗雄激素治疗更有效的方法。我们也 假设与导致耐药的前列腺癌细胞的抗雄激素不同的是， 非规范AR信号程序，以AR为目标的AUTOTAC平台不太可能导致非规范 AR信号相关的恶性表型。目标1将表征AR LBD-的分子作用 目标AUTOTAC(Enz-AUTOTAC)和AR DBD目标AUTOTAC(vPC-AUTOTAC)，并评估其 前列腺癌细胞模型的治疗效果。Aim 2将评估Enz-2的治疗效果 PTEN基因敲除和患者来源异种移植(PDX)小鼠体内的AUTOTAC和vPC-AUTOTAC 前列腺癌模型。耐药肿瘤中潜在致癌通路的激活将是 检测AR的表达水平和AR变异体的状态。除 肿瘤细胞、肿瘤异质性、肿瘤细胞可塑性和肿瘤微环境的转录组分析 也将在药物治疗前后通过单细胞RNA-seq分析进行评估。这些数据可能会导致 目的：探讨抗去势PCa中额外治疗靶点(S)的确定。 建议研究的成功完成将为AR开发一个革命性的药物平台 CRPC患者的降解剂。

Androgen receptor (AR) plays a critical role in prostate cancer (PCa) in all stages. While a majority of patients with PCa initially respond to androgen deprivation and/or anti-androgen therapies, a significant portion of patients develop castrate-resistant prostate cancer (CRPC). Clinical studies showed that CRPC is often enriched with AR splice variants lacking the ligand binding domain (LBD), thereby being constitutively active in an androgen-independent manner and escaping from the antiandrogen enzalutamide-mediated AR inhibition. The goal of this RO1 application is to develop and characterize novel therapeutics that effectively degrade (remove) AR proteins in PCa. Technical innovations include the development of a novel therapeutic platform for AR protein degradation using autophagy-targeting chimera (AUTOTAC). We successfully generated AR- targeted AUTOTACs, which are bifunctional molecules, composed of enzalutamide (an AR ligand binding domain inhibitor) or VPC-14449 (an AR DNA binding domain inhibitor) as a target binding ligand, linked to YTK-6-2 as a ligand of the autophagic cargo receptor p62/Sequestosome-1/SQSTM1. AR-targeted AUTOTAC brings the target protein AR to p62, forming a ternary complex. YTK-6-2 induces p62 self-oligomerization, resulting in AR-p62 oligomeric complexes. YTK-6-2-activated p62 facilitates AR-p62-LC3 interaction on autophagic membranes and promotes autophagosome biogenesis and degradation of AR proteins. Using clinically relevant animal models that reflect the relevant tumor microenvironment and tumor heterogeneity, we will test our novel hypothesis that AUTOTAC-mediated degradation (removal) of AR and its variants is a more effective approach than the currently available therapeutics including anti-androgen therapy. We also hypothesize that unlike anti-androgens which result in therapy-resistant PCa cells involving activation of noncanonical AR signaling programs, the AR-targeted AUTOTAC platform is unlikely to result in noncanonical AR signaling-associated malignant phenotypes. Aim 1 will characterize the molecular actions of AR LBD- targeted AUTOTAC (Enz-AUTOTAC) and AR DBD-targeted AUTOTAC (VPC-AUTOTAC), and evaluate their therapeutic efficacies in prostate cancer cell models. Aim 2 will evaluate the therapeutic efficacies of Enz- AUTOTAC and VPC-AUTOTAC in vivo using PTEN knockout and patient-derived xenograft (PDX) mouse models of prostate cancer. Activation of potential oncogenic pathways in therapy-resistant tumors will be examined in relation to the expression levels of AR and the status of AR variants. In addition to the transcriptome analysis of tumor cells, tumor heterogeneity, cancer cell plasticity and tumor microenvironments will also be assessed by single cell RNA-seq analysis before and after drug treatments. These data may lead to the identification of additional therapeutic target(s) in castrate-resistant PCa. Successful completion of the proposed study will develop a revolutionary drug platform of AR degraders for patients with CRPC.