Xie Jiaheng, Zhang Pengpeng, Liu Yuankun, Wu Dan, Ou Xueqi, Wang Ming, Yan Wei, Liu Jianlan, Tang Jian, Ni Tianyi, Ma Chenfeng, Tang Qikai, Zhao Songyun, Qi Min
Department of Burns and Plastic Surgery, Shenzhen Hospital, Southern Medical University, Shenzhen, Guangdong, People's Republic of China.
Department of Plastic Surgery, Xiangya Hospital, Central South University, Changsha, 410008, P. R. China.
J Transl Med. 2025 Jul 10;23(1):778. doi: 10.1186/s12967-025-06812-9.
The role of post-translational modifications(PTMs) in PD-L1-mediated immune resistance and melanoma progression remains poorly understood.
We conducted multi-omics analyses and constructed a prognostic model based on PTM-related genes using machine learning to identify key regulators in melanoma. In vitro and in vivo experiments, including cell culture, flow cytometry, and subcutaneous allografts models, were used to investigate USP5's function. Protein-protein interactions were validated using Western blotting and co-immunoprecipitation, while PD-L1 stability and ubiquitination were assessed using cycloheximide (CHX) chase and ubiquitination assays.
USP5 was identified as a key DUB that specifically deubiquitinates K48-linked polyubiquitin chains on PD-L1, stabilizing its protein levels. USP5 knockdown reduced PD-L1 expression, enhanced CD8 + T-cell infiltration and activation, and suppressed melanoma progression in both in vitro and in vivo models. Furthermore, combining USP5 knockdown with anti-PD-1 therapy significantly improved therapeutic efficacy by reducing tumor burden and promoting T-cell activation.
USP5 promotes immune escape in melanoma by stabilizing PD-L1 through deubiquitination, representing a novel mechanism hindering the efficacy of ICIs. Targeting USP5 could enhance anti-PD-1 therapy and improve patient outcomes. These findings underscore the therapeutic potential of USP5 inhibition as a strategy to overcome immune resistance in melanoma.
翻译后修饰（PTM）在程序性死亡配体1（PD-L1）介导的免疫抵抗和黑色素瘤进展中的作用仍知之甚少。
我们进行了多组学分析，并使用机器学习构建了一个基于PTM相关基因的预后模型，以识别黑色素瘤中的关键调节因子。采用体外和体内实验，包括细胞培养、流式细胞术和皮下同种异体移植模型，来研究泛素特异性蛋白酶5（USP5）的功能。通过蛋白质免疫印迹法和免疫共沉淀法验证蛋白质-蛋白质相互作用，同时使用放线菌酮（CHX）追踪实验和泛素化实验评估PD-L1的稳定性和泛素化情况。
USP5被鉴定为一种关键的去泛素化酶，它特异性地去除PD-L1上与K48连接的多聚泛素链，从而稳定其蛋白质水平。在体外和体内模型中，敲低USP5均可降低PD-L1表达，增强CD8+T细胞浸润和活化，并抑制黑色素瘤进展。此外，将敲低USP5与抗程序性死亡蛋白1（PD-1）治疗相结合，可通过减轻肿瘤负荷和促进T细胞活化，显著提高治疗效果。
USP5通过去泛素化稳定PD-L1，促进黑色素瘤的免疫逃逸，这代表了一种阻碍免疫检查点抑制剂（ICI）疗效的新机制。靶向USP5可增强抗PD-1治疗效果并改善患者预后。这些发现强调了抑制USP5作为克服黑色素瘤免疫抵抗策略的治疗潜力。
