Ubiquitination and Degradation in Cancer Therapy

描述（由申请人提供）：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亡原因。雄激素依赖性前列腺癌患者的初始治疗包括激素治疗，以抑制雄激素受体（AR）信号传导的生物学效应。最近的证据表明，AR对雄激素难治性前列腺癌细胞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转换的主要途径，涉及在底物上组装泛素链，然后靶向多泛素化蛋白，由26S蛋白酶体降解。一种被称为SCF （Skp1, Cullin， F-box和Hrtl/Rbx）泛素连接酶的蛋白质复合物特异性靶向泛素化和随后的降解。我们之前证明了桥接分子或Protac（蛋白水解靶向嵌合分子）通过scf - 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体外泛素化。我们合成了一种由AR配体、二羟睾酮（DHT）和结合scf - trcp的kappa α -磷酸肽组成的Protac （Protac-3）。我们的目标是开发一种新技术，其中Protac将AR与scf - β - trcp连接，从而导致AR的泛素化和降解。

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.