[Ornithine decarboxylase activity in malignant tumors].

Activity of ornithine decarboxylase was studied in transplantable hepatomas G-27, G-22, G-61, G-60, G-48, G-46, in liver tissues of tumor-bearing and intact animals as well as in liver tissue during hepatocarcinogenesis and after repeated administration of nitrose piperidine. The rate of ornithine decarboxylation was distinctly increased in hepatomas G-27, G-60, G-46 and G-48 as compared with liver tissue of tumor-bearing and intact animals. The enzymatic activity in hepatomas G-22 and G-61 was similar to the activity found in liver tissue of intact animals. In liver tissue of tumor-bearing animals the enzyme activity was significantly increased only in hepatoma 22. Repeated administration of nitrose piperidine did not affect the ornithine decarboxylase activity in rat liver tissue. The carcinogenesis, caused by nitrosamine effect, increased distinctly the enzymatic activity in rat liver tissue up to the moment of the primary hepatomas development.