Some Studies of the Metabolism of Deoxycytidine-2-C14 by Hepatoma Cells

Previous work in this laboratory has established that the nucleoside, deoxycytidine, is a major component of the deosyribosyl compounds present in cold acid extracts of the blood and of certain tissues of the rat (l-3), and that considerable amounts of deoxycytidine are excreted daily in the urine (4).Although Reichard and Estborn (5) established some time ago that this nucleoside is a specific precursor of the pyrimidine bases of deoxyribonucleic acid and, more recently ( 6)) that deosycytidine is incorporated into deoxyribonucleic acid without prior degradation, little is known about the intermediary metabolism of this compound in animal tissues.In the experiments to be reported here, the metabolism of deosycytidine-2-C 14 by hepatoma cells was studied.It was found that these cells, in addition to incorporating the nucleoside into deoxyribonucleic acid, convert most of the added deosycytidine to deoxyuridine.Furthermore, the specific activity of the deoxycytidine recovered from these cells progressively declines, indicating that the hepatoma cells continually form this compound.