SIRT5-DBT功能调控轴通过AR-V7参与前列腺癌去势抵抗的机制研究

雄激素剥夺治疗（ADT）是中晚期前列腺癌的重要治疗方法，然而肿瘤仍会逐步进展为对ADT治疗不敏感的去势抵抗性前列腺癌（CRPC），从而进入疾病致死阶段。CRPC的发生机制复杂，雄激素受体剪切变异体AR-V7可能发挥重要作用。我们前期发现AR-V7的蛋白稳定性可能与支链α-酮酸脱氢酶(BCKDH)复合物E2酶DBT密切相关，且DBT受到去酰化酶SIRT5的去琥珀酰化作用。我们推测SIRT5可能通过对DBT的去琥珀酰化修饰，改变DBT的支链氨基酸（BCAA）代谢酶活性，通过调节肿瘤微环境中BCAA水平或通过DBT相关蛋白，影响AR-V7的蛋白稳定性或活性，进而导致CRPC的发生。本项目计划利用蛋白质相互作用、酶活性及代谢产物检测、体外培养细胞株及前列腺癌小鼠模型等方法，揭示SIRT5-DBT-AR-V7功能轴在CRPC发生过程中的功能联系和分子机制，探索干预相关靶点来治疗CRPC的可行性。

ADT has been the standard of care for advanced prostate cancers. However, almost all patients eventually become resistant to ADT treatment, and progress to castration-resistant prostate cancer (CRPC). Versatile mechanisms are involved in the development of drug resistance in CRPC, among which AR-V7 overexpression has been documented as an essential cause. We found that the protein stability of AR-V7 and its nuclear tranlocation was regulated by dihydrolipoamide branched-chain transacylase (DBT), the E2 enzyme component of the branched-chain α-keto acid dehydrogenase complex (BCKDH).In addition, DBT associated with SIRT5 in prostate cancer cells, and its lysine succinylation was inhibited by overexpression of SIRT5.Therefore, we hypothesize that SIRT5 enhances the enzymatic activity of DBT by desuccinylation, leading to upregulated protein stability and nuclear translocation of AR-V7 via alteration of the branched chain amino acids (BCAAs) in the tumor microenvironment or DBT-associated proteins, resulting in the development of CRPC. This study is to investigate the relationship between among SIRT5, DBT and AR-V7, and reveal the molecular mechanism of SIRT5-DBT-AR-V7 axis in drug resistance in CRPC by utilizing preotin-protein interaction, enzymatic activity and the related metabolite assays in cell lines in vitro and prostate cancer xegnograft models in vivo. Furthermore, we plan to explore SIRT5-DBT-AR-V7 targeted intervention to improve the efficacy of ADT in CRPC. This study will contribute to a better understanding of drug resistance, and will provide the rationale for the new SIRT5-DBT-AR-V7 targeted therapy in CRPC.