title: Genetic analysis of 2',3'-dideoxycytidine incorporation into cultured human T lymphoblasts.
abstract: In order to analyze the cellular determinants that mediate the action of 2',3'-dideoxycytidine, the growth inhibitory and cytotoxic effects and the metabolism of the dideoxynucleoside were examined in wild type human CEM T lymphoblasts and in mutant populations of CEM cells that were genetically deficient in either nucleoside transport or deoxycytidine kinase activity. Whereas 2',3'-dideoxycytidine at a concentration of 5 microM inhibited growth of the wild type CEM parental strain by 50%, two nucleoside transport-deficient clones were 4-fold resistant to the pyrimidine analog. The deoxycytidine kinase-deficient cell line was virtually completely resistant to growth inhibition by the dideoxynucleoside at a concentration of 1024 microM. An 80% diminished rate of 2',3'-[5,6-3H]dideoxycytidine influx into the two nucleoside transport-deficient lines could account for their resistance to the dideoxynucleoside, while the resistance of the deoxycytidine kinase-deficient cells to 2',3'-dideoxycytidine toxicity could be explained by a virtually complete failure to incorporate 2',3'-[5,6-3H]dideoxycytidine in situ. Two potent inhibitors of mammalian nucleoside transport, 4-nitrobenzylthioinosine and dipyridamole, mimicked the effects of a genetic deficiency in nucleoside transport with respect to 2',3'-dideoxycytidine toxicity and incorporation. These data indicate that the intracellular metabolism of 2',3'-dideoxycytidine in CEM cells is initiated by the nucleoside transport system and the cellular deoxycytidine kinase activity.
authors.affiliation: Department of Biochemistry, Oregon Health Sciences University, Portland 97201.
authors.forename: B
authors.initials: B
authors.lastname: Ullman
authors.forename: T
authors.initials: T
authors.lastname: Coons
authors.forename: S
authors.initials: S
authors.lastname: Rockwell
authors.forename: K
authors.initials: K
authors.lastname: McCartan
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000188:drug therapy; D001692:Biological Transport; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D003842:Deoxycytidine Kinase / Q000235:genetics* / Q000378:metabolism; D004176:Dipyridamole / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D007945:Leukemia, Lymphoid; D009154:Mutation; D009705:Nucleosides / Q000378:metabolism*; D010766:Phosphorylation; D010770:Phosphotransferases / Q000235:genetics*; D013601:T-Lymphocytes / Q000378:metabolism*; D013868:Thioinosine / Q000031:analogs & derivatives / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D016047:Zalcitabine
chemical_list: D009705:Nucleosides; D003841:Deoxycytidine; D013868:Thioinosine; D004176:Dipyridamole; D016047:Zalcitabine; D010770:Phosphotransferases; D003842:Deoxycytidine Kinase; C001789:4-nitrobenzylthioinosine