孤儿核受体ERRalpha作为转移性去势抵抗性前列腺癌治疗靶标的探索性研究

Current treatment options for metastatic castration-resistant prostate cancer (mCRPC) are still limited and also mostly ineffective. Our previous study shows that estrogen-related receptors alpha (ERRα) can promote hypoxic and normoxic cell growth via its augment HIF-1 signaling pathway in prostate cancer. However, the significance of orphan nuclear receptor ERRα in the devepment and progression of CRPC in particular mCRPC remains unclear. Our preliminary study revealed that increased expression of ERRα in an in vivo model of CRPC in SCID mice. Intriguingly, overexpression of ERRα in LNCaP prostate cancer cells, which accompanied with an increased expression of genes invovled in sterodiogenesis including CYP11A1，CYP17A1, HSD3B2 and AKR1C3 can facilitated both androgen-independent and anti-androgen-resistant cell growth phenotypes. Moreover, both these androgen-independent growth phenotypes and genes expression patterns can be further validated by shRNA-mediated ERRα knock-down approach. Besides, we also found that shRNA-mediated ERRα knock-down can decrease protein leveles of T：E fusion gene in VCaP prostate cancer cells. Based on our novel findings, we hypothesize that increased expression of ERRα gene may contribute to the androgen-independent cell growth and advanced progression of prostate cancer via following mechanisms: 1) inccrease intratumoral androgen synthesis by directly regulating the expression of genes involved in steroidogenesis and 2) directly regulating the expression of T: E fusion gene which facilitates the metastasis of CRPC. To verify our hypothesis, we plan to use “loss-of-function study and “gain-of-function study” methods to assess in vitro growth response to androgen deprivation and anti-androgen resistance of ERRα and tranfectants and detect effects of ERRα on the expression levels of genes invovled in sterodiogenesis and intracelluar androgen levels. Further more, chromatin immunoprecipitation and luciferase reporter assay will be used to invesitigate the regulation mechanism of ERRα on regulation of genes invovled in steroidgenesis pathway and T:E fusion gene. The functional role of ERRα in mCRPC will be further confirmed in in vitro cell models and in vivo metastatic mice CRPC models. We strongly believe that through this study, we will not only gain a better understanding on the novel role of ERRα in CRPC progression and metastasis but also can disect the regulatory mechanisms between orphan nulcear reptor ERRα and T:E fusion which would provide insight that targeting ERRα could be a potential therapeutic strategy for advanced prostate cancer management.

转移性去势抵抗性前列腺癌（mCRPC）是临床治疗和基础研究的重点和难点。ERRα在mCRPC发展过程中的作用目前尚未明了。我们前期研究发现：1）ERRα和T:E融合基因在CRPC小鼠异体移植瘤中同时表达增高;2）ERRα过表达的LNCaP细胞呈雄激素非依赖性生长且雄激素合成相关酶表达升高。我们推测ERRα可能通过上调雄激素合成相关酶的表达以增加肿瘤内雄激素合成从而促进CRPC的发生同时调控T:E的表达以促进CRPC的转移。本研究拟通过调节前列腺癌细胞内ERRα的表达，在细胞水平和小鼠CRPC模型中研究ERRα对雄激素非依赖性生长和雄激素合成的影响；利用Lucifase和ChIP实验探讨ERRα对雄激素合成酶以及T：E的表达调控机制；并进一步在小鼠模型中考察ERRα对CRPC远处转移的影响，以阐明ERRα在mCRPC发展过程中的作用，为寻找mCPRC新的药物靶点提供科学依据。

转移性去势抵抗性（雄激素非依赖性）前列腺癌（mCRPC metastatic castration-resistant prostate cancer）是临床治疗和基础研究的重点和难点。本项目紧紧围绕“转移性雄激素非依赖性前列腺癌”这一核心问题，以“核受体ERR调控前列腺癌肿瘤内雄激素合成”为切入点，研究ERRα在雄激素非依赖性前列腺癌转化和转移中的作用和机制，通过分析ERRα和PGC-1α/β在激素治疗前的前列腺癌样本和CRPC以及发生了转移的CRPC样本中的表达水平并结合前列腺癌雄激素非依赖性异体移植瘤小鼠去势模型检测了ERRα，PGC-1α/β与T:E融合基因在CRPC小鼠模型中的表达情况，揭示了ERR的表达在雄激素非依赖性前列腺癌转化和转移中的作用与T:E融合基因表达的关系。在此基础上，建立了ERRα基因沉默和过表达前列腺癌稳转细胞系，研究其对前列腺癌细胞雄激素非依赖性生长、抗雄激素耐受和在去势的免疫缺陷小鼠中成瘤能力的影响，探讨了ERRα的基因沉默和过表达对前列腺癌细胞雄激素非依赖性生长、细胞内和免疫缺陷鼠CRPC皮下移植瘤内雄激素水平的影响，从细胞水平和动物体内水平上阐明了ERRα对前列腺癌肿瘤内雄激素合成的影响以及ERRα在前列癌雄激素非依赖转化过程的作用。另从mRNA转录水平研究了前列腺癌细胞内基因沉默和过表达ERRα对雄激素合成通路中关键性酶编码基因表达的影响并探讨了ERRα对雄激素合成通路中关键性酶编码基因的启动子转录活性和结合位点，为ERRα对肿瘤内雄激素信号通路和促进CRPC发生的调控机制提供依据。基于ERR在转移性CRPC中的作用，考察了CRPC小鼠移植瘤内ERR在与T:E融合基因的表达相关性；在细胞水平考察了过表达、基因沉默ERR和ERR特异性拮抗剂XCT790处理对T:E融合基因表达的影响，在分子水平探讨了ERR对T:E融合基因的启动子转录活性和结合位点的调节，阐明ERR对T:E融合基因的调控机制，并研究了基因沉默T:E融合基因对ERR过表达的前列腺细胞体外迁移和体内转移的影响，确定ERRα是否通过调控T:E的表达促进CRPC的远处转移，初步阐明ERRα促进促进CRPC的远处转移的调控机制。