Transport, phosphorylation, and toxicity of a tricyclic nucleoside in cultured Novikoff rat hepatoma cells and other cell lines and relase of its monophosphate by the cells
Plagemann, P.G.
Journal of the National Cancer Institute 57(6): 1283-1295
1976
ISSN/ISBN: 0027-8874 PMID: 187799 Document Number: 101908
1,4,5,6,8-Pentaazaacenaphthylene-3-amino-1,5-dihydro-5-methyl-(5-14C)-1-.beta.-D-ribofuranosyl (NSC-154020), a tricyclic 7-deazapurine nucleoside (TCN), was rapidly incorporated into the acid-soluble pool by cultured Novikoff rat hepatoma cells, mouse formate into nucleotides and nucleic acids of Novikoff cells. Inhibition of the de novo synthesis of purine and pyrimidines was not the only toxic effect of the TCN since high concentrations of uridine, adenine, guanine and hypoxanthine, alone or combined, failed to prevent the inhibition of cell replication by TCN. Between 1 and 3 h of treatment, 70-80% of the Novikoff cells fragmented into 4-8 vesicles/cell. These fragments were impermeable to trypan blue, still exhibited some metabolic activity such as the phosphorylation of AMP and TCN, but failed to replicate when the drug was removed. No similar fragmentation was observed with the other cell lines. Novikoff and L-cells rapidly released TCN-MP into the culture fluid. After 4 h of incubation, 70-100% of the total radioactivity in the medium was associated with the MP. Only a little TCN-MP was released from HeLa and HEp-2 cells. A TCN resistant mutant of Novikoff cells failed to phosphorylate the analog and was deficient in adenosine kinase.