Effects of granulocyte-macrophage colony-stimulating factor on 3'-azido-3'-deoxythymidine uptake, phosphorylation and nucleotide retention in human U-937 cells.
Previous studies have demonstrated that granulocyte-macrophage colony-stimulating factor (GM-CSF) both increases and decreases levels of 3'-azido-3'-deoxythymidine (AZT) nucleotides in certain human myeloid cells. The present studies have examined the effects of GM-CSF on AZT metabolism in U-937 cells. The results demonstrate that GM-CSF stimulated AZT nucleotide formation in these cells. This stimulation was detectable during concurrent exposure to GM-CSF and AZT or as a result of pretreatment with GM-CSF. The GM-CSF-induced enhancement in AZT nucleotide formation was associated with a 4-fold increase in AZT uptake. The finding that uptake of AZT into U-937 cells was only partially sensitive to 6-[(4-nitrobenzyl)thio]-9-beta-D-ribofuranosylpurine (NBMPR) suggested a process primarily involving nonfacilitated diffusion. The results also demonstrate that treatment of U-937 cells with GM-CSF was associated with nearly a 2-fold increase in thymidine kinase activity. Moreover, the findings indicate that retention of AZT-MP and AZP-TP was prolonged significantly (P less than 0.05 and P less than 0.01 respectively) in association with GM-CSF treatment. Taken together, these results suggest that GM-CSF enhances the formation of AZT nucleotides by increasing AZT uptake and phosphorylation, as well as increasing retention of phosphorylated derivatives.
Dhawan
R K
RK
Laboratory of Clinical Pharmacology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115.
Kharbanda
S
S
Nakamura
M
M
Ohno
T
T
Kufe
D
D
D001692:Biological Transport / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D054306:Dideoxynucleotides; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D009000:Monocytes / Q000378:metabolism*; D010766:Phosphorylation; D013868:Thioinosine / Q000031:analogs & derivatives / Q000494:pharmacology; D013937:Thymidine Kinase / Q000378:metabolism; D013942:Thymine Nucleotides / Q000378:metabolism; D014407:Tumor Cells, Cultured; D015215:Zidovudine / Q000031:analogs & derivatives / Q000378:metabolism*
D054306:Dideoxynucleotides; D013942:Thymine Nucleotides; C064181:3'-azido-3'-deoxythymidine 5'-diphosphate; C057287:3'-azido-3'-deoxythymidine 5'phosphate; D013868:Thioinosine; D015215:Zidovudine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D013937:Thymidine Kinase; C001789:4-nitrobenzylthioinosine