Differential expression of hepatic apurinic/apyrimidinic endonuclease 1,a DNA repair enzyme,in chronic hepatitis

AIM:To determine hepatic expression of apurinic/apyrimidinic endonuclease 1(APE-1)and 8-hydroxydeoxyguanosine(8-OHdG)in patients with chronic hepatitis B and C.METHODS:Liver biopsies were obtained from 27 patients with chronic hepatitis B virus(HBV),30 with chronic hepatitis C virus(HCV),6 with autoimmune hepatitis(AIH),and 6 with primary biliary cirrhosis(PBC).Normal liver tissue was obtained from surgical resection specimens of four patients.Hepatic APE-1 protein and mRNA expression were assayed by Western blot and by real-time polymerase chain reaction,respectively.Hepatocellular APE-1 and 8-OHdG expression were determined by immunohistochemistry.RESULTS:The staining intensity of hepatocellular nuclear APE-1 was lower in the HBV group than in the other groups(P < 0.05).Hepatic APE-1 protein levels were reduced in the HBV group relative to the other groups.Hepatic APE-1 mRNA levels were also lower in the HBV group.The proportion of hepatocytes with 8-OHdG-positive nuclei was increased in the HCV,AIH and PBC groups(P < 0.05),but not in the HBV group.Hepatocellular nuclear APE-1 levels were positively correlated with hepatocellular 8-OHdG levels in both the HBV and HCV groups(HBV,r = 0.34,P < 0.05;HCV,r = 0.54,P < 0.01).CONCLUSION:An imbalance between oxidative DNA damage and APE-1 expression may contribute to hepatocarcinogenesis in chronic viral hepatitis.