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Unstable, non-mutational expression of resistance to the thymidine analogue, trifluorothymidine in CHO cells

Journal Article · · Mutat. Res.; (United States)
The thymidine analogue, 5-trifluoromethyl-2'-deoxyuridine, or trifluorothymidine (TFT), has been reported to be an effective selecting agent for thymidine kinase-deficient (TK/sup -/) mutants in a mutagenesis assay system employing a tk/sup + -/heterozygote of L5178Y mouse lymphoma cells. Although 5-bromo-2'-deoxyuridine (BUdR) and 5-iodo-2'-deoxyuridine (IUdR have been commonly used to select TK/sup -/ mutants, considerable cell division and slow killing of wild-type (WT) cells occur in the presence of these drugs. TFT, however, rapidly inhibits cell division, and unlike BUdR and IUdR, is not mutagenic in mammalian cells. All three analogues are mutagenic in T4. TFT is readily phosphorylated by thymidine kinase (TK), competitively inhibiting utilization of the normal substrate. The phosphorylated derivative of TFT is a potent, irreversible inhibitor of thymidylate synthetase. Further phosphorylation to the di- or tri-phosphates and incorporation into the DNA of mammalian cells in culture have also been demonstrated.
Research Organization:
Univ. of California, Livermore
OSTI ID:
5365608
Journal Information:
Mutat. Res.; (United States), Journal Name: Mutat. Res.; (United States) Vol. 60; ISSN MUREA
Country of Publication:
United States
Language:
English