p21WAF1/CTP1 Expression and Hepatitis Virus Type

Since p21 WAF1/CIP1 (p21) is a universal inhibitor of cyclin-dependent kinases and is regulated transcriptionally by p53, which is activated by DNA stress, its expression reflects DNA stress in chronic hepatitis. Recently an association with both hepatitis B and C virus and the expression of p53 or p21 was reported. We analyzed p21 expression in 18 cases of HBV-associated chronic liver diseases and 32 cases of HCV-associated chronic liver diseases by immunohistochemical analysis, and investigated the possible association between hepatocyte p21 expression and hepatic inflammation, fibrosis, and especially hepatitis virus type. The p21-positive hepatocytes were more numerous in areas of intense inflammation and spotty necrosis and areas close to fibrosis, and they increased according to the degrees of grading and staging. The p21 labeling index (LI) in patients with liver cirrhosis was significantly higher than that in patients with chronic hepatitis of both hepatitis viral types (5.84 ± 0.61 vs 12.0 ± 0.83, P < 0.0001 in hepatitis B, 10.28 ± 0.80 vs 15.6 ± 1.09, P = 0.0004 in hepatitis C), Furthermore, the p21 LI was significantly higher in HCV-associated liver disease than in HBV-associated liver disease in every group (4.02 ± 0.48 vs 7.74 ± 0.96, P = 0.021 in low grade group, 7.35 ± 0.46 vs 12.8 ± 0.57, P < 0.0001 in high grade, 12.0 ± 0.83 vs 15.6 ± 1.09, P = 0.034 in liver cirrhosis). In, conclusion, p21 expression was up-regulated by the stress of inflammation and fibrosis and might be influenced by viral proteins in human chronic liver disease.