P21 expression and its relation to disease activity and hepatocyte proliferation in chronic hepatitis B virus infection.

BACKGROUND/AIMS: P21 protein, a cell cycle regulatory protein expressed in the liver, acts as an inhibitor of cyclin dependent kinase and prevents progression of the cell cycle. In the present study, our aim was to investigate the relationships between P21 protein expression and hepatocyte proliferation, hepatitis B virus replication, and hepatitis activity.

METHODS

A total of 66 patients with chronic hepatitis B without cirrhosis were included in the study. These patients were evaluated in three different groups according to the degree of viral replication and the disease activity. Group 1: HBeAg-positive patients with active liver disease and with viral replication, group 2: HBeAg-negative patients with active liver disease and with viral replication, and group 3: HBeAg-negative inactive carriers. P21 and proliferating cell nuclear antigen were immunohistochemically stained and a labeling index was calculated for each protein.

RESULTS

A total of 32 (48.4%) patients were positive for nuclear P21 expression. All three groups had a similar P21 index. proliferating cell nuclear antigen-labeling index, hepatit B virus DNA levels, ALT levels, and HAI scores were not different in patients with and without P21 staining. Spearman's correlation analysis found no correlation between P21 staining and ALT and hepatit B virus DNA levels, HAI score and proliferating cell nuclear antigen-labeling index.

CONCLUSIONS

These results suggest that the pattern of P21 expression is not associated with histological activity, hepatocyte proliferation and virus replication in patients with well-compensated chronic hepatitis B.