Department of Dermatology, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China
Department of Dermatology, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China.
J Immunother Cancer. 2020 Dec;8(2). doi: 10.1136/jitc-2020-001866.
The therapeutic effect of immune checkpoint blockers, especially the neutralizing antibodies of programmed cell death (PD-1) and its ligand programmed death ligand 1 (PD-L1), has been well verified in melanoma. Nevertheless, the dissatisfactory response rate and the occurrence of resistance significantly hinder the treatment effect. Inflammation-related molecules like A20 are greatly implicated in cancer immune response, but the role of tumorous A20 in antitumor immunity and immunotherapy efficacy remains elusive.
The association between tumorous A20 expression and the effect of anti-PD-1 immunotherapy was determined by immunoblotting, immunofluorescence staining and flow cytometry analysis of primary tumor specimens from melanoma patients. Preclinical mouse model, in vitro coculture system, immunohistochemical staining and flow cytometry analysis were employed to investigate the role of A20 in regulating the effect of anti-PD-1 immunotherapy. Bioinformatics, mass spectrum analysis and a set of biochemical analyzes were used to figure out the underlying mechanism.
We first discovered that upregulated A20 was associated with impaired antitumor capacity of CD8T cells and poor response to anti-PD-1 immunotherapy in melanoma patients. Subsequent functional studies in preclinical mouse model and in vitro coculture system proved that targeting tumorous A20 prominently improved the effect of immunotherapy through the invigoration of infiltrating CD8T cells via the regulation of PD-L1. Mechanistically, A20 facilitated the ubiquitination and degradation of prohibitin to potentiate STAT3 activation and PD-L1 expression. Moreover, tumorous A20 expression was highly associated with the ratio of Ki-67 percentage in circulating PD-1CD8T cells to tumor burden.
Together, our findings uncover a novel crosstalk between inflammatory molecules and antitumor immunity in melanoma, and highlight that A20 can be exploited as a promising target to bring clinical benefit to melanomas refractory to immune checkpoint blockade.
免疫检查点抑制剂的治疗效果，特别是程序性细胞死亡（PD-1）及其配体程序性死亡配体 1（PD-L1）的中和抗体，已在黑色素瘤中得到充分验证。然而，令人不满意的反应率和耐药性的发生显著阻碍了治疗效果。像 A20 这样的炎症相关分子在癌症免疫反应中具有重要意义，但肿瘤 A20 在抗肿瘤免疫和免疫治疗效果中的作用仍不清楚。
通过免疫印迹、免疫荧光染色和黑色素瘤患者原发肿瘤标本的流式细胞术分析，确定肿瘤 A20 表达与抗 PD-1 免疫治疗效果的关系。采用临床前小鼠模型、体外共培养系统、免疫组织化学染色和流式细胞术分析，研究 A20 在调节抗 PD-1 免疫治疗效果中的作用。采用生物信息学、质谱分析和一系列生化分析来探讨其潜在机制。
我们首先发现，上调的 A20 与黑色素瘤患者肿瘤 CD8T 细胞抗肿瘤能力受损和对抗 PD-1 免疫治疗反应不良有关。随后在临床前小鼠模型和体外共培养系统中的功能研究证明，通过调节 PD-L1，靶向肿瘤 A20 可通过增强浸润性 CD8T 细胞的活力显著改善免疫治疗效果。从机制上讲，A20 促进了抑素的泛素化和降解，从而增强了 STAT3 的激活和 PD-L1 的表达。此外，肿瘤 A20 表达与循环 PD-1CD8T 细胞中 Ki-67 百分比与肿瘤负担的比值高度相关。
总之，我们的研究结果揭示了黑色素瘤中炎症分子与抗肿瘤免疫之间的一种新的相互作用，并强调 A20 可以作为一个有前途的靶点，为对抗免疫检查点阻断的黑色素瘤带来临床获益。
