Increased synthesis of N1-acetylspermidine in hepatic preneoplastic nodules and hepatomas.

Hepatic preneoplastic nodules and hepatomas obtained in a multistep protocol of rat hepatocarcinogenesis (diethylnitrosamine, 2-acetylaminofluorene, and partial hepatectomy) showed high values of spermidine N1-acetyltransferase activity, the rate-limiting enzyme in polyamine interconversion. Such an increase was associated with the appearance of N1-acetylspermidine, an enhancement in putrescine, and a decline in spermine. Such changes suggest an activation of the interconversion pathway of high into lower polyamines in hepatic preneoplastic nodules and hepatomas.