核受体ERRα通过调控线粒体分裂维持前列腺癌干细胞干性的作用和机制研究

去势抵抗性前列腺癌 (CRPC) 是前列腺癌治疗的难点。既往研究证实：前列腺癌干细胞 (PCSCs) 在CRPC发生发展中发挥关键作用，但其分子机制尚未阐明。本研究前期结果表明：ERRα在具有干性的前列腺癌细胞中高表达；干预ERRα表达可影响PCSCs功能；同时，ERRα可通过调控MFF表达及DRP1-pS616水平两种机制影响PCSCs内的线粒体分裂。因此，我们推测：ERRα可能通过调控PCSCs内线粒体的分裂参与其干性的维持，从而促进CRPC的发生发展。本项目拟：(1) 通过干预ERRα表达或活性进一步阐明ERRα调控PCSCs干性的作用；(2) 揭示ERRα通过调控线粒体分裂维持PCSCs干性的机制；(3) 通过体内干预ERRα的表达或活性，探索ERRα作为CRPC治疗靶点的临床转化价值。本研究将首次阐明ERRα维持PCSCs干性的作用和机制，为CRPC治疗新靶标的开发提供科学依据。

A major clinical hurdle for the management of advanced prostate cancer is the resistance of tumors to androgen deprivation therapy (ADT) and their subsequent progression into castration-resistant prostate cancer (CRPC). Although the mechanisms underlying the development to CRPC are still incompletely understood, recent advances indicate that a small population of tumor cells grown within the tumors, called prostate cancer stem cells (PCSCs), which are characterized by their self-renewal and enhanced tumor initiation capacities, may play a crucial role in the advanced development of CRPC and therapy-resistance. However, how these PCSCs are regulated in their self-maintenance and their contribution to advanced CRPC still remains largely undefined. Our previous results showed ERRα displayed up-regulated expression in enriched PCSCs. Functional studies indicated that ERRα was required for the maintenance of their stem-like properties in prostate cancer cells, as its genetic knockout or drug-induced inactivation triggered self-renewal arrest in vitro and suppressed tumorigenicity in vivo, whereas its overexpression promoted the self-renewal capacity and increased the expression of CSC markers. In addition, we demonstrated that ERRα could control the mitochondrial fission of PCSCs via its regulation of mitochondrial fission factor (MFF) and phosphorylation of dynamic related protein 1 (DRP1) at S616 (DRP1-pS616). Based on these results, we hypothesize that ERRα may enable the maintenance of PCSCs by its control of mitochondrial fission via its transactivation of the MFF gene and its regulation of the DRP1-pS616 level. In this proposal, we plan (1) to determine the functional role of ERRα in maintaining the stem-like characteristics of PCSCs by “loss-of-function” and “gain-of-function” studies, (2) to dissect the targets and signaling pathways involved in the ERRα-mediated growth regulation of PCSCs by bioinformatics analysis, luciferase reporter assay, ChIP assay and rescue studies, and (3) to evaluate the therapeutic significance of targeting ERRα in the treatment of CRPC via suppression of ERRα activity in vivo exerted by its specific inverse agonist, or via knockout of ERRα gene in vivo mediated by CRISPR/Cas9 system. We strongly believe that through this proposed study, we will not only have a better understanding on the specific role of ERRα in the growth regulation of PCSCs but also provide an insight on the potential treatment values of targeting ERRα or PCSCs for the advanced CRPC.