A non-radioactive sensitive assay to measure 5-fluorouracil incorporation into DNA of solid tumors

Nucleosides Nucleotides Nucleic Acids. 2004 Oct;23(8-9):1481-4. doi: 10.1081/NCN-200027699.


A non-radioactive method to determine 5-Fluorouracil (5FU) incorporation into DNA has been developed. Isolated DNA was enzymatically degraded to bases and the resulting 5FU was measured with standard gas-chromatography coupled to mass spectrometry (GC-MS) and compared with that of radioactive 5FU in a cell line. Incorporation into DNA of the murine Colon 26-B tumor treated with maximal tolerated doses of 5FU and fluorodeoxyuridine (FUdR) was maximal after 2 hour and was 15.4 and 71.0 fmol/microg DNA, respectively. After a plateau for about 3 days a decrease was observed to +/- 2 fmol/microg DNA after 10 days. The assay is very sensitive and reproducible and can be used in a clinical setting.

MeSH terms

  • Animals
  • Antimetabolites, Antineoplastic / pharmacokinetics*
  • Cell Line, Tumor
  • Colonic Neoplasms / drug therapy
  • DNA / drug effects*
  • DNA / metabolism
  • Drug Screening Assays, Antitumor / methods*
  • Floxuridine / pharmacology*
  • Fluorouracil / pharmacokinetics*
  • Gas Chromatography-Mass Spectrometry / methods*
  • Mice
  • Neoplasms / drug therapy*
  • Sensitivity and Specificity
  • Time Factors


  • Antimetabolites, Antineoplastic
  • Floxuridine
  • DNA
  • Fluorouracil