5-Fluoro-2'-deoxyuridine incorporation in L1210 DNA.

We have employed cesium sulfate density gradient centrifugation to separate RNA and DNA of L1210 cells labeled with [3H]fluorodeoxyuridine. We have analyzed nucleotide and nucleoside digests of purified DNA from the [3H]fluorodeoxyuridine-labeled cells and demonstrate by reverse phase and anion exchange high pressure liquid chromatography the presence of tritium radioactivity co-migrating with fluorodeoxyuridine 5'-monophosphate or fluorodeoxyuridine. These observations demonstrate the internucleotide incorporation of fluorodeoxyuridine in DNA and suggest a new mechanism of action for this cytotoxic and mutagenic agent.