Induction of Aldose Reductase Gene Expression in LEC Rats during the Development of the Hereditary Hepatitis and Hepatoma

We examined age‐related changes in the protein and the mRNA expression of aldose reductase in livers of Long‐Evans with a cinnamon‐like color (LEC) rats, which develop hereditary hepatitis and hepatoma with aging, using Long‐Evans with an agouti color rats as controls. The levels of the protein and mRNA of aldose reductase increased after 20 weeks, at the stage of acute hepatitis, and were maintained at 60 weeks of age, while those of aldehyde reductase seemed to be constant at all ages. The expression of aldose reductase was marked in cancerous lesions in hepatoma‐bearing LEC rat liver compared to uninvolved surrounding tissues. These results indicated that elevation of aldose reductase accompanied hepatocarcinogenesis and may be related to the acquisition of immortality of the cancer cells through detoxifying cytotoxic aldehyde compounds.