Expression of p21(waf‐1/cip‐1) Is Significantly Induced in the Livers of LEC Rats with Chronic Liver Injury

It is reported that hepatocytes isolated from LEC rats with chronic liver injury show reduced growth activity in primary culture. To elucidate the molecular basis of this phenomenon, we examined expression of p21(waf‐1/cip‐1) and p27, cyclin‐dependent kinase inhibitors, by northern blot analysis. The expression of p21(waf‐1/cip‐1) in the LEC rat liver was 3‐fold higher than that of age‐matched SD rat liver, while there was no significant difference in p27 expression level. Western blot analysis also revealed a significant increase in p2l(waf‐1/cip‐1) in the nuclear matrix fraction of the LEC rat liver. Immunohisto‐chemically, p21(waf‐1/cip‐1) was detected in the nuclei of normal LEC rat hepatocytes, but not in those of hepatocellular carcinoma cells, suggesting selective growth of neoplastic hepatocytes.