PCNA and hepatocellular carcinoma: For example, the covalently closed circular DNA (cccRNA) is a pivotal factor in HBV‐related HCC by inducing HBV viral persistence, and recently Zhang et.al 37 found that the proliferating cell nuclear antigen (PCNA) gene, targeted by miR‐153, is participating in the axis of cccRNA/HBV, which enhance the hepatocarcinogenesis.