Polysomal poly(A)+ RNA in liver of rats fed 3'-methyl-4-dimethylaminoazobenzene and in hepatoma induced by the same carcinogen.

Feeding of carcinogenic azo dyes to rats results in a release into the cytoplasm of RNA sequences which in liver cells of control animals are degraded in the cell nucleus. A cross-hybridization of polysomal poly(A)+ RNA from liver of rats fed the hepatocarcinogen 3'-methyl-4-dimethylaminoazobenzene and from liver of control animals with their complementary DNA has shown, that the disruption of the processing and/or release of nuclear RNA induced by the carcinogen is not reflected in a change in the polysomal poly(A)+ RNA. After 17 weeks of feeding the hepatocarcinogen, there is no difference in the sequence complexity of polysomal poly(A)+ RNA in the liver. It is therefore not probable that the RNA sequences released from the nucleus by the azo dye serve as a template for protein synthesis. An alteration in the polysomal poly(A)+ RNA population was observed only temporarily at an earlier stage of feeding of the azocarcinogen. It coincided with the regeneration of the liver in a response to the initial toxic effect of the azocarcinogen. Therefore, it is probable that this alteration is the result of a temporary change in the population of liver cells. A cross-hybridization of liver and hepatoma complementary DNA with the polysomal poly(A)+ RNA from both organs have shown an overlap of the polysomal poly(A)+ RNA sequences of the hepatoma with the sequences present in the liver, with many liver sequences missing, or present only in very low concentration in the hepatoma.