Biomaterial Database

5-fluorouracil-methotrexate synergy: enhancement of 5-fluorodeoxyridylate binding to thymidylate synthase by dihydropteroylpolyglutamates. 1980

D J Fernandes, and J R Bertino

Ternary complex formation of thymidylate synthase (5,10-methylenetetrahydrofolated:dUMP C-methyltransferase, EC 2.1.1.45), 5-fluorodeoxyuridylate (FdUMP), and poly(gamma-glutamyl) conjugates of pteroate and methotrexate (MTX) has been examined as a basis for the sequence-dependent synergism of the 5-fluorouracil-MTX combination in inhibiting viability of L1210 murine tumor cells. A 1.4-log (25-fold) increase in the inhibition of soft agar colony formation was observed when MTX preceded 5-fluorouracil as compared to the reverse sequence. L1210 cells converted 39% of the total intracellular MTX into MTX poly(gamma-glutamate)s within 4 hr of exposure to 1 microM MTX. MTX and MTX(gamma-glutamate) formed reversible ternary complexes with FdUMP on one site of thymidylate synthase, whereas with 7,8-dihydropteroylpentaglutamate and I-5,10-methylenetetrahydropteroylpentaglutamate stoichiometric binding of FdUMP to two sites on thymidylate synthase was observed. The dissociation constants for FdUMP in the ternary complexes formed in the presence of MTX, MTX(gamma-glutamate), 7,8-dihydropteroylpentaglutamate, and I-5-10-methylenetetrahydropteroylpentaglutamate were estimated to be 370, 27, < 10, and < 10 nM, respectively, by equilibrium dialysis. We propose that the sequence-dependent effect of MTX plus 5-fluorouracil on L1210 cell viability results from MTX and MTX polyglutamate inhibition of dihydrofolate reductase (tetrahydrofolate dehydrogenase; 5,6,7,8-tetrahydrofolate:NADP+ oxidoreductase, EC 1.5.1.3) and consequently a trapping of intracellular folates as dihydropteroylpolyglutamates, which increase the extent of FdUMP binding to thymidylate synthase.

UI	MeSH Term	Description	Entries
D007939	Leukemia L1210	An experimental LYMPHOCYTIC LEUKEMIA of mice.	Leukemia L 1210,L 1210, Leukemia,L1210, Leukemia
D008727	Methotrexate	An antineoplastic antimetabolite with immunosuppressant properties. It is an inhibitor of TETRAHYDROFOLATE DEHYDROGENASE and prevents the formation of tetrahydrofolate, necessary for synthesis of thymidylate, an essential component of DNA.	Amethopterin,Methotrexate Hydrate,Methotrexate Sodium,Methotrexate, (D)-Isomer,Methotrexate, (DL)-Isomer,Methotrexate, Dicesium Salt,Methotrexate, Disodium Salt,Methotrexate, Sodium Salt,Mexate,Dicesium Salt Methotrexate,Hydrate, Methotrexate,Sodium, Methotrexate
D008780	Methyltransferases	A subclass of enzymes of the transferase class that catalyze the transfer of a methyl group from one compound to another. (Dorland, 28th ed) EC 2.1.1.	Methyltransferase
D011099	Polyglutamic Acid	A peptide that is a homopolymer of glutamic acid.	Polyglutamate
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011624	Pteroylpolyglutamic Acids	Derivatives of folic acid (pteroylglutamic acid). In gamma-glutamyl linkage they are found in many tissues. They are converted to folic acid by the action of pteroylpolyglutamate hydrolase or synthesized from folic acid by the action of folate polyglutamate synthetase. Synthetic pteroylpolyglutamic acids, which are in alpha-glutamyl linkage, are active in bacterial growth assays.	Folate Polyglutamates,Polyglutamate Folates,Pteroylpolyglutamates,Acids, Pteroylpolyglutamic,Folates, Polyglutamate,Polyglutamates, Folate
D002470	Cell Survival	The span of viability of a cell characterized by the capacity to perform certain functions such as metabolism, growth, reproduction, some form of responsiveness, and adaptability.	Cell Viability,Cell Viabilities,Survival, Cell,Viabilities, Cell,Viability, Cell
D004357	Drug Synergism	The action of a drug in promoting or enhancing the effectiveness of another drug.	Drug Potentiation,Drug Augmentation,Augmentation, Drug,Augmentations, Drug,Drug Augmentations,Drug Potentiations,Drug Synergisms,Potentiation, Drug,Potentiations, Drug,Synergism, Drug,Synergisms, Drug
D005467	Floxuridine	An antineoplastic antimetabolite that is metabolized to fluorouracil when administered by rapid injection; when administered by slow, continuous, intra-arterial infusion, it is converted to floxuridine monophosphate. It has been used to treat hepatic metastases of gastrointestinal adenocarcinomas and for palliation in malignant neoplasms of the liver and gastrointestinal tract.	FUdR,Fluorodeoxyuridine,5-FUdR,5-Fluorodeoxyuridine,5 Fluorodeoxyuridine
D005472	Fluorouracil	A pyrimidine analog that is an antineoplastic antimetabolite. It interferes with DNA synthesis by blocking the THYMIDYLATE SYNTHETASE conversion of deoxyuridylic acid to thymidylic acid.	5-FU,5-FU Lederle,5-FU Medac,5-Fluorouracil,5-Fluorouracil-Biosyn,5-HU Hexal,5FU,Adrucil,Carac,Efudex,Efudix,Fluoro-Uracile ICN,Fluoroplex,Fluorouracil Mononitrate,Fluorouracil Monopotassium Salt,Fluorouracil Monosodium Salt,Fluorouracil Potassium Salt,Fluorouracil-GRY,Fluorouracile Dakota,Fluorouracilo Ferrer Far,Fluoruracil,Fluracedyl,Flurodex,Haemato-FU,Neofluor,Onkofluor,Ribofluor,5 FU Lederle,5 FU Medac,5 Fluorouracil,5 Fluorouracil Biosyn,5 HU Hexal,Dakota, Fluorouracile,Fluoro Uracile ICN,Fluorouracil GRY,Haemato FU