EFFECTS OF 5-FLUORO-2'-DEOXYURIDINE ON DNA METABOLISM IN HELA-CELLS

Abstract

5-Fluoro-2''-deoxyuridine [5-fluoro-dUrd] at a concentration of 0.1 .mu.M completely inhibited incorporation of radioactivity from [3H]dUrd [[3H]deoxyuridine] into DNA in [human cervical carcinoma] HeLa S3 cells within 5 min of exposure. The dTTP pool size decreased from 800 to 300 pmol/107 cells by 1 h and then gradually increased after 3 h of exposure. Although the incorporation of radioactivity from [32P]H3PO4 into DNA was inhibited, the relative incorporation into smaller fragments compared with larger fragments of DNA was increased in the drug-treated cells. When the cells with [14C]thymidine-prelabeled DNA were exposed to 5-fluoro-dUrd, shifts of labeled DNA peaks to smaller sizes were observed 5-18 h after exposure, as analyzed by alkaline sucrose gradient centrifugation. Exposure of cells to 1 and 10 .mu.M 5-fluoro-[3H]dUrd caused incorporation of radioactivity into DNA. As shown by high-performance liquid chromatographic analysis of nucleosides, almost all of the radioactivity was incorporated as 5-fluoro-dUrd.