Targeting EZH2 depletes LMP1-induced activated regulatory T cells enhancing antitumor immunity in nasopharyngeal carcinoma
Wei‐Zen Sun, Lin Chen, Jun Tang, Chengcheng Zhang, Yihui Wen, Weiping Wen
Abstract
Objective: Regulatory T cells (Tregs) are critical factors that impair antitumor immunity. Epstein–Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) is one of the most pathogenic factors in nasopharyngeal carcinoma (NPC). However, the role of EBV-encoded LMP1 in regulating Treg generation in NPC remains unclear.Materials and Methods: The in vitro stability of activated Tregs (aTregs) influenced by LMP1 was analyzed by flow cytometry. The inhibitory effects of LMP1-HONE1 antigen-induced aTregs on tumor-associated antigen (TAA)-specific T cells were analyzed in vitro and in vivo. Finally, the expression of LMP1, Foxp3, and enhancer of zeste homolog 2 (EZH2) were analyzed in samples from 86 NPC patients by immunohistochemistry and immunofluorescence.Results: LMP1 upregulated the expression of EZH2, which increased the stability of aTregs in vitro. EZH2 inhibitor, DZnep, depleted LMP1-HONE1 antigen-induced aTregs in vitro and led to potent TAA-specific T cell antitumor immunity in vivo. In NPC tissues, LMP1 expression level was positively correlated with the number of EZH2+ Tregs, which was positively correlated with clinical stage and overall survival.Conclusions: EZH2 is essential for maintaining the stability and inhibitory functions of aTregs that are induced by EBV-encoded LMP1 in NPC.