ENHANCEMENT OF THE INCORPORATION OF 5-FLUORODEOXYURIDYLATE INTO DNA OF HL-60 CELLS BY METABOLIC MODULATIONS

Abstract

The exposure of HL-60 human promyelocytic leukemia cells to 0.5 .mu.M 5-fluoro-2''-[3H]deoxyuridine (FdUrd) for 16 h resulted in the incorporation of 5.14 .+-. 0.31 (S.D.) .times. 10-7 mol FdUrd into DNA per mol of DNA nucleotide, which corresponds to 0.146 .+-. 0.082 pmol FdUrd per 107 cells. Pretreatment with 50 .mu.M deoxythymidine for 24 h led to a 2.7-fold increase in the incorporation of this analogue into newly synthesized DNA during the ensuing 16-h exposure to 0.5 .mu.M [3H]FdUrd incorporation into newly synthesized DNA approximately 5-fold. The coexistence of deoxythymidine or methotrexate with [3H]FdUrd, however, led to decreased incorporation of FdUrd into DNA. More than 50% of the radioactivity in DNA separated by Cs2SO4 equilibrium density gradient centrifugation was proven to be fluorodeoxyuridylate by means of its binding to Lactobacillus casei deoxythymidine monophosphate synthetase.