Abstract: Objective To explore the expression of Per2 in hepatocellular carcinoma (HCC) and its effect on the survival of HCC patients, and to analyze the effects of Per2 on the proliferation and apoptosis of SMMC-7721 cells. Methods The protein expression of Per2 in HCC patients was analyzed by immunohistochemical (IHC) staining. SMMC-7721 cells were transfected with Per2 eukaryotic expression plasmid. The protein expression of Per2 was detected by Western blot. The cell proliferation and apoptosis was detected by MTS and flow cytometry. Results In 117 HCC tissues, the Per2 positive expression rate was 70.94%, which was significantly lower than that of 87.18% in the adjacent HCC tissue. The Per2 staining score was 2.14±1.76, which was significantly lower than that of 6.39±3.84 in the adjacent HCC tissue (P<0.01). Per2 expression was related to tumor diameter, portal vein invasion and TNM staging (P<0.05) in 117 HCC patients. The overall survival (OS) and recurrence-free survival (RFS) of HCC patients with low expression of Per2 were shorter than those with Per2 high expression (P<0.05). The cell proliferation was significantly inhibited and the level of apoptosis was increased with the transfection of Per2 eukaryotic expression plasmid in SMMC-7721 cells (P<0.05). Conclusions The expression of Per2 in HCC was significantly reduced. Per2 inhibits the progression of HCC, possibly by inhibiting cell proliferation and promoting apoptosis.

Key words: Per2, prognosis, proliferation, apoptosis, HCC