IMPAIRED PHORBOL ESTER-INDUCED HEPATOCYTE PROLIFERATION IN CIRRHOSIS

Cirrhotic Livers are considered to regenerate less actively than norma l livers after hepatic resection. Little is known about the mechanisms responsible for impaired capacity of regeneration in cirrhotic liver. In the present study, we investigated the effect of phorbol ester on hepatocyte proliferation in healthy and cirrhotic hepatocytes, using o ne of the phorbol esters, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), which has a direct effect on activation of protein kinase C (PKC). Ci rrhosis was established by the administration of carbon tetrachloride and pheno-barbitd to rats. Healthy and cirrhotic hepatocytes were isol ated from Wistar male rats by a two-step collagenase perfusion techniq ue. DNA synthesis was estimated by [H-3]thymidine incorporation into D NA and by autoradiographic nuclear labeling index. [H-3]Thymidine inco rporation was measured 24 hr after hepatocytes were stimulated by appr opriate reagents. TPA (50 nM) stimulated [H-3]thymidine incorporation in healthy hepatocytes (control vs TPA, 991 +/- 247 vs 2569 +/- 766 me an +/- SEM cpm/mu g DNA; P < 0.05), whereas TPA (50 nM) failed to stim ulate in cirrhotic hepatocytes (control vs TPA, 1144 +/- 184 vs 1304 /- 187 cpm/mu g DNA; NS). Staurosporine, a specific PKC inhibitor, sup pressed [3H]thymidine incorporation in TPA-stimulated healthy hepatocy tes (806 +/- 263 cpm/mu g DNA; P < 0.05); however, it had no effect on cirrhotic hepatocytes (1295 +/- 180 cpm/mu g DNA; NS). An autoradiogr aphic nuclear labeling index exhibited the same results with [H-3]thym idine incorporation. We conclude that TPA stimulates hepatocyte prolif eration in healthy rat hepatocytes but has no effect on cirrhotic hepa tocytes. (C) 1995 Academic Press, Inc.