[Expression of insulin-like growth factor II mRNA and its relation to the differentiation of preneoplastic hepatocytes in rats]

Expression of insulin-like growth factor II (IGF II) mRNA was studied during the early stage of diethylnitrosamine-induced hepatocarcinogenesis in rats according to Solt-Farber's protocol. The DNA-RNA dot blot hybridization denoted that the expression of IGF II mRNA in the liver of experimental animals were 13-15 folds more than those in the normal controls, while the expression level of the uninitiated animals or the rats 24 hours after a similar 2/3 hepatectomy were similar to the normal rat's. The RNA-RNA in situ hybridization showed that the over expression of IGF II was detected in some "preneoplastic" hepatocytic foci and nodules, which was usually accompanied by altered ornithine carbamyol transferase and carbamyol phosphate synthetase I expressions, while no over expression of IGF II was seen in those foci of normal OCT and CPS I expression. Since OCT and CPS I have been used as the differentiation markers of the liver cells, it is considered that over expression of IGF II in DEN initiated liver cells is closely related to de- or aberrant differentiation of the altered hepatocytes which might play an important role in the early stage of hepatocarcinogenesis.