前列腺癌中SPOP介导的ZMYND8非降解型泛素化修饰调控DNA损伤应答的机制研究

Prostate cancer is one of the most common malignant tumors in men. Many sophisticated genetic factors may contribute to the incidence of prostate cancer. SPOP，an E3 ubiquitin ligase, is the most frequently mutated in prostate cancer. In recent years, it has been found that SPOP is closely related to the DNA damage response in tumor. However, the mechanism remains unknown. Under conditions of DNA damage, ZMYND8 could recognize H4K16ac and recruit NuRD complex to damage sites to promote homology-directed repair. Here we demonstrate that wild-type SPOP binds to and induces ubiquitination of ZMYND8 protein without affecting its protein stability. In contrast, prostate cancer-associated SPOP mutants are deficient in binding to and mediating ubiquitination of ZMYND8. The ubiquitination of ZMYND8 by SPOP is significantly enhanced under conditions of DNA damage. Therefore, we speculate that the ubiquitination of ZMYND8 by SPOP may be involved in SPOP-mediated DNA damage response. In this study, the effect of ZMYND8’s ubiquitination by SPOP in terms of DNA damage response is investigated. This research aims to explore the new mechanism of incidence of prostate cancer and provides theoretical basis for the selection of patients in the treatment of prostate cancer.

前列腺癌是男性最常见的恶性肿瘤之一，研究认为其发病具有非常复杂的遗传因素。SPOP是一个E3泛素连接酶，同时也是前列腺癌中点突变发生频率最高的基因，近年研究发现其与肿瘤细胞DNA损伤修复密切相关，而具体作用机制目前并不清楚。在DNA损伤条件下，ZMYND8基因可以识别H4K16ac，同时招募NuRD蛋白复合体到DNA损伤位点抑制基因转录，促进同源重组修复功能。本研究前期发现SPOP可以结合并泛素化修饰ZMYND8且不影响其蛋白稳定性，而SPOP基因高频点突变对ZMYND8的泛素化修饰减弱或消失，在DNA损伤条件下SPOP对ZMYND8的泛素化修饰明显增强，因此我们推测SPOP对ZMYND8的泛素化修饰可能参与了SPOP介导的DNA损伤修复。本课题将研究SPOP对ZMYND8的泛素化修饰对于ZMYND8行使其DNA损伤修复功能的影响，以期为前列腺癌药物治疗中的患者选择提供理论依据。

前列腺癌是男性最常见的恶性肿瘤之一，研究认为其发病具有非常复杂的遗传因素。SPOP是一个E3泛素连接酶，同时也是前列腺癌中点突变发生频率最高的基因。本研究中我们通过酵母双杂交实验发现了一个SPOP的新的泛素化底物TEAD2，而TEAD2作为转录因子是HIPPO信号通路下游的关键效应分子，通过免疫共沉淀实验证实SPOP与TEAD2存在蛋白水平的相互作用，进一步的泛素化等实验发现SPOP基因可以泛素化修饰并降解TEAD2蛋白，而在前列腺癌中SPOP高频突变对于TEAD2蛋白的泛素化修饰及蛋白降解效果减弱或消失。进一步实验证实SPOP通过对TEAD2的降解抑制了Hippo通路下游靶基因，进而影响了部分由TEAD2介导的前列腺癌的增殖以及侵袭转移。通过本研究的探索提示Hippo通路相关靶基因的抑制剂可能在今后治疗SPOP突变的前列腺癌中发挥一定的作用，并为该亚型前列腺癌的精准治疗提供了理论依据。