Studies on the mechanism of carcinogenesis (IX)--Differential expression of proliferating and tissue-specific enzyme genes during hepatocarcinogenesis.

With cDNA fragments of CPS1, OCT and ACT as probes, dot and Northern blot analyses of poly(A)+-RNA from rat liver with different pathological lesions during carcinogenesis induced by diethylnitrosamine were conducted. It was shown that the level of mRNA of tissue-specific enzymes, CPSI and OCT decreased while that of the proliferating enzyme ACT mRNA increased, and the alteration was correlated with the degree of pathological changes in each case. The relative changes in the mRNA level of these enzymes during hepatocarcinogenesis were correlated with that of enzyme activities. Implication of these findings in the mechanism of carcinogenesis in terms of cell proliferation and differentiation was discussed.