Ubiquitination and Degradation in Cancer Therapy

描述(申请人提供)：前列腺癌是男性中最常见的癌症类型，也是第二常见的癌症死因。雄激素依赖型前列腺癌患者的初步治疗包括激素治疗，以抑制雄激素受体(AR)信号的生物学效应。最近的证据表明，AR对雄激素耐药的前列腺癌细胞中的肿瘤生长至关重要。泛素蛋白酶体途径是所有真核细胞中蛋白质周转的主要途径，它涉及到在底物上组装泛素链，然后以26S蛋白酶体降解多泛素蛋白为靶标。SCF(Skp1、Cullin、F-box和Hrtl/RBX)泛素连接酶是一种蛋白质复合体，专门针对泛素化和后续降解的蛋白质。我们以前证明了桥联分子或Protac(靶向嵌合分子的蛋白水解酶)在体外通过SCFbeta-TRCP促进稳定蛋白蛋氨酸氨基肽酶-2和不稳定蛋白雌激素受体的泛素化。我们合成了一个Protac(Protac-3)，它由AR配体、二羟睾酮(DHT)和与SCFbeta-TRCP结合的kappa(Balpha-磷酸肽)组成。我们的目标是开发一种新的技术，其中Protac将AR连接到SCFbeta-TRCP，导致AR泛素化和降解。 这项建议的具体目的是：1)测试假设，即磷酸肽-DHT嵌合体(Protac-3)将AR与SCFbeta-TRCP连接，并在体外指导AR的泛素化和降解；2)测试磷肽-DHT嵌合体(Protac-3)将AR与SCFbeta-TRCP连接，并增加AR的泛素化和降解的假说；以及3)测试可与β-TRCP结合的小非肽配体可用于产生增加AR泛素化和降解的基于睾酮的ProTacs的假说。我们假设AR可以靶向SCFbeta-TRCP，从而增加前列腺癌细胞中AR的周转。这项技术的发展将导致治疗雄激素依赖型和非雄激素依赖型疾病的新方法，希望能提高前列腺癌患者的存活率。

DESCRIPTION (provided by applicant): Prostate cancer is the most common type of cancer diagnosed in men and the second most common cause of death from cancer. Initial therapy for patients with androgen-dependent prostate cancer includes hormonal therapy to inhibit the biological effects of androgen receptor (AR) signaling. Recent evidence suggests that the AR is critical for tumor growth in androgen-refractory prostate cancer cells. The ubiquitin proteasome pathway is the primary pathway for protein turnover in all eukaryotic cells that involves the assembly of an ubiquitin chain on a substrate, which then targets the multi-ubiquitinated protein for degradation by the 26S proteasome. A protein complex known as, the SCF (Skp1, Cullin, F-box, and Hrtl/Rbx) ubiquitin ligase specifically targets proteins for ubiquitination and subsequent degradation. We previously demonstrated that a bridging molecule or Protac (Proteolysis Targeting Chimeric molecule) promotes in vitro ubiquitination of a stable protein, Methionine Aminopeptidase-2, and an unstable protein, the estrogen receptor, by SCFbeta-TRCP. We have synthesized a Protac (Protac-3) consisting of the ligand of AR, dihydroxytestosterone (DHT), and the kappa(Balpha-phosphopeptide, which binds SCFbeta-TRCP. Our goal is to develop a new technology in which a Protac links the AR to SCFbeta-TRCP, resulting in ubiquitination and degradation of AR. The specific aims of this proposal are to: 1) Test the hypothesis that a phosphopeptide-DHT chimera (Protac-3) will link AR to SCFbeta-TRCP, and direct the ubiquitination and degradation of AR in vitro; 2) Test the hypothesis that a phosphopeptide-DHT chimera (Protac-3) will link AR to SCFbeta-TRCP, and increase the ubiquitination and degradation of AR in cells; and 3) Test the hypothesis that small non-peptidic ligands that bind beta-TRCP can be used to generate testosterone-based Protacs that increase AR ubiquitination and degradation. We hypothesize that AR can be targeted to SCFbeta-TRCP resulting in increased turnover of AR in prostate cancer cells. Development of this technology will lead to novel approaches to treat androgen dependent and -independent disease in hopes of improving the survival of men with prostate cancer.