title: The subcellular location of nucleoside analog phosphorylation is a determinant of synergistic effects of hydroxyurea.
abstract: The ribonucleotide reductase inhibitor hydroxyurea exhibits synergistic pharmacological activity with several nucleoside analogs used in antiviral and anticancer chemotherapy. We have used a cell model system where a deoxycytidine kinase (dCK)-deficient cell line was reconstituted with genetically engineered dCK targeted to the cytosol, the nucleus, or the mitochondria to investigate how the subcellular location of nucleoside analog phosphorylation affected the synergistic effects of a ribonucleotide reductase inhibitor. Hydroxyurea showed synergistic cytotoxicity with the nucleoside analogs 1-beta-d-arabinofuranosylcytosine and 2-chloro-2'-deoxyadenosine when dCK was expressed in the cytosol or in the nucleus, but not when dCK was expressed in the mitochondria. These data indicate that the synergistic effect of ribonucleotide reductase inhibition is limited to nucleoside analogs phosphorylated in the cytosol or the cell nucleus.
authors.affiliation: Division of Clinical Virology, Karolinska Institute, Stockholm, S-141 86, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Zhu
authors.forename: M
authors.initials: M
authors.lastname: Johansson
authors.forename: A
authors.initials: A
authors.lastname: Karlsson
mesh_terms: D000818:Animals; D016466:CHO Cells; D002451:Cell Compartmentation; D002467:Cell Nucleus; D006224:Cricetinae; D003600:Cytosol; D003842:Deoxycytidine Kinase / Q000172:deficiency; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006918:Hydroxyurea / Q000494:pharmacology*; D009705:Nucleosides / Q000494:pharmacology*; D010766:Phosphorylation; D012264:Ribonucleotide Reductases / Q000037:antagonists & inhibitors
chemical_list: D004791:Enzyme Inhibitors; D009705:Nucleosides; D012264:Ribonucleotide Reductases; D003842:Deoxycytidine Kinase; D006918:Hydroxyurea