Elucidating a Novel Mechanism for SPOP in Suppressing Prostate Tumorigenesis

摘要： 最近的密集研究表明，复发性体细胞突变也是前列腺癌的一个关键特征。 值得注意的是，SPOP(斑点型POZ蛋白)的突变，其功能是底物相互作用的适配器 基于cullin 3的E3泛素连接酶存在于10%-15%的原发人类前列腺癌中，代表着 前列腺癌(PrCa)七种亚型之一的分子特征。然而，分子 SPOP调节前列腺癌发生的机制和生理作用在很大程度上仍不清楚。 此外，尽管最近几年已经确定了几种泛素下游底物，用于库尔林 3SPOP，控制SPOP稳定性的上游信号通路在很大程度上是未知的。因此，主要目标是 这项建议是为了探索上游调节因子以及发现一种新的肿瘤抑制作用 库林3SPOP泛素E3连接酶在前列腺癌环境中控制肿瘤发生的作用。为此，我已经 获得的初步数据表明，脱泛素酶OTUD3，而不是其他OTUD家族 成员，专门交互和取消对SPOP的访问。更重要的是，我识别了Nanog，一种转录 在维持癌细胞的自我更新和干性方面起关键作用的因子，作为一种新的 SPOP的泛素底物。这一关键发现首次将SPOP E3的肿瘤抑制作用联系起来 连接酶对前列腺癌干细胞的调节作用。在本提案中，我计划：1)将OTUD3描述为 上游调节因子，主要通过SPOP的去泛素化来积极调节SPOP的稳定性；2) 确定cullin 3SPOP在抑制前列腺癌发生中的生理作用，主要是通过多聚- 泛素化和Nanog的降解；3)决定SPOP突变是否以及如何影响前列腺癌 肿瘤在体内的发展和转移。我职业生涯的长期目标是应用 分子和细胞生物学以了解解除调节的蛋白分解途径的生理意义 在人类恶性肿瘤，特别是前列腺癌的发展过程中非常重要的基因，并寻找 合适的可下药靶点。这个K99/R00奖项将为我提供追求小说的时间 这一建议的假设，获得新的技能集来执行实验和解决问题。此外， 获奖还将使我能够专注于独立开展基础研究和翻译研究，以及 培养未来癌症生物学领域的年轻科学家。如果我获得这个奖项，我将继续这样做 哈佛医学院贝丝以色列女执事医疗中心(BIDMC)的研究，那里的当局 泛素E3连接酶与前列腺癌的研究定位。建议的研究结果将有所帮助。 阐明新发现的SPOP突变是否可以在体内直接调控前列腺癌的发生。 阻断其下游多能性维持转录因子Nanog能否延缓前列腺癌 癌症进展。

Abstract: Recent intensive studies revealed that recurrent somatic mutation is also a key feature of prostate cancer. Notably, mutations in SPOP (Speckle-type POZ protein), which functions as a substrate-interacting adaptor for the Cullin 3-based E3 ubiquitin ligase, occur in 10%-15% of primary human prostate cancers, representing as the molecular feature of one of the seven sub-types of prostate cancer (PrCa). However, the molecular mechanism and physiological role of SPOP in regulating prostate tumorigenesis remains largely elusive. Moreover, although several downstream ubiquitin substrates have been identified in recent years for Cullin 3SPOP, the upstream signaling pathway to control SPOP stability is largely unknown. Hence, the major goal of this proposal is to explore the upstream regulator as well as to uncover a novel tumor suppressor role of the Cullin 3SPOP ubiquitin E3 ligase in controlling tumorigenesis in the prostate cancer setting. To this end, I have obtained preliminary data showing that the deubiquitinating enzyme OTUD3, but not other OTUD family member, specifically interacts and dequbiquitinates SPOP. More importantly, I identified Nanog, a transcription factor that plays a pivotal role in the maintance of self-renewal and stemness of cancerous cells, as a novel ubiquitin substrate of SPOP. This critical finding, for the first time, links the tumor suppressive role of SPOP E3 ligase to the regulation of prostate cancer stem cells. In this proposal, I plan to: 1) Characterize OTUD3 as an upstream regulator that positively regulates SPOP stability largely through deubiquitination of SPOP; 2) Determine the physiological role of Cullin 3SPOP in suppressing prostate tumorigenesis largely through poly- ubiquitination and degradation of Nanog; 3) Determine whether and how SPOP mutation contributes prostate cancer development and metastasis in vivo. The long-term goals of my career are to apply the insights of molecular and cellular biology to understand the physiological significance of deregulated proteolytic pathways that are important in the development of human malignancies, especially in prostate cancer, and to search for proper druggable targets. This K99/R00 award will provide protected time for me to pursue the novel hypotheses of this proposal, obtain new skill sets to execute experiments and solve problems. In addition, the award will also allow me to focus my efforts on independently conducting basic and translational research, and to train future young scientists in the cancer biology field. Should I receive this award, I will pursue this research at Beth Israel Deaconess Medical Center (BIDMC), Harvard Medical School, where authorities in the fields of ubiquitin E3 ligase and prostate cancer research locate. The outcome of the proposed studies will help elucidate whether the newly identified SPOP mutations could directly regulate prostate tumorigenesis in vivo, and whether blocking its downstream pluripotency maintaining transcription factor Nanog could retard prostate cancer progression.