In addition, studies have shown that the overexpression of EZH2 can inhibit programmed cell death protein 1 (PD-L1) in prostate cancer and hepatocellular carcinoma by enhancing the H3K27me3 level of the interferon regulatory factor 1(IRF1) transcription factor (22, 23). This evidence concerns the gene PDCD1 and hepatocellular carcinoma.