title: Enhancement by thymidine of 5-fluorouracil's inhibition of thymidylate synthetase in human tumors.
abstract: The effects of thymidine (TdR) on the conversion of 5-fluorouracil (5-FU) to 5-fluoro-2'-deoxyuridine-5'-monophosphate and the resulting inhibition of thymidylate synthetase was determined in crude, human tissue extracts. TdR alone has no effect but it augmented the inhibition of thymidylate synthetase produced by 5-FU. TdR augmentation was probably mediated either by increasing 5-FU conversion to 5-fluoro-2'-deoxyuridine-5'-monophosphate or by inhibiting 5-FU catabolism.
mesh_terms: D004357:Drug Synergism; D004359:Drug Therapy, Combination; D005260:Female; D005468:Fluorodeoxyuridylate / Q000378:metabolism; D005472:Fluorouracil / Q000008:administration & dosage* / Q000378:metabolism; D006801:Humans; D008780:Methyltransferases / Q000037:antagonists & inhibitors*; D009369:Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D013936:Thymidine / Q000008:administration & dosage*; D013940:Thymidylate Synthase / Q000037:antagonists & inhibitors*
chemical_list: D005468:Fluorodeoxyuridylate; D008780:Methyltransferases; D013940:Thymidylate Synthase; D005472:Fluorouracil; D013936:Thymidine