Proliferating cell nuclear antigen (PCNA) expression in regenerating rat liver after partial hepatectomy.

Proliferating cell nuclear antigen (PCNA) is a nuclear protein maximally elevated in the S phase of proliferating and transformed cells and is recognized by the monoclonal antibody PC-10 in paraffin tissue sections. The liver regenerative process after partial hepatectomy in rats was estimated with the in vivo incorporation of [3H]thymidine into liver DNA and the liver thymidine kinase activity. The expression of PCNA in rat liver after partial hepatectomy was performed by immunohistochemical staining with PC-10 in paraffin embedded tissues, at different time intervals up to 240 hr. Proliferating cell nuclear antigen expression, [3H]thymidine incorporation into DNA, and liver thymidine kinase activity exhibited marked oscillations during the liver regenerative process. A close relationship was demonstrated among DNA synthesis, thymidine kinase activity, and PC-10 score. Our results suggest that PC-10 monoclonal antibody may be used as a worthwhile proliferation index in the evaluation of the rate of liver regeneration in rats.