Distribution and Metabolism of Calcium Leucovorin in Normal and Tumor Tissue

  • Robert J. Mullin
  • Barry R. Keith
  • David S. Duch
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 131)


Thymidylate synthase catalyzes the formation of thymidylate from deoxyuridine monophosphate in a reaction which employs the folate cofactor CH2-H4PteGlu both as methyl donor and reductant. The TS inhibitor FUra has been widely used clinically for the treatment of solid tumors, particularly colorectal carcinomas. Inhibition of TS by FUra occurs following its metabolism to FdUMP and formation of a ternary complex involving TS, FdUMP and CH2-H4PteGlu (1–3). An increased interest in the use of FUra stems from the observations in tissue culture (4, 5) and in extracts of human colon adenocarcinoma xenographs (6) that the antitumor effects of FUra can be potentiated by the administration of exogenous folates in the form of calcium leucovorin. The results of these studies indicated that the response of many tumors to FUra is limited by the intracellular concentration of CH2-H4PteGlu and that the metabolism of 5-CHO-H4PteGlu to CH2-H4PteGlu following cellular uptake expands this cofactor pool. With increased intracellular levels of CH2-H4PteGlu, the half-life of the ternary complex is increased, resulting in increased cytoxicity. In support of this model, enlargement of the CH2-H4PteGlu pool following administration of 5-CHO-H4PteGlu has been demonstrated in tissue culture (7).


Sodium Ascorbate Plasma Folate Thymidylate Synthetase Total Folate Tetrahydrofolic Acid 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    D.V. Santi, and C.S. McHenry, 5-Fluoro-2’-Deoxyuridylate: Covalent Complex with Thymidylate Synthetase, Proc. Natl. Acad. Sci. 69: 1855 (1972).PubMedCrossRefGoogle Scholar
  2. 2.
    R.J. Langenbach, P.V. Danenberg, and C. Heidelberger, Thymidylate Synthetase: Mechanism of Inhibition by 5-Fluoro-2’Deoxyuridylate, Biochem. Biophys. Res. Comm. 48: 1565 (1972).PubMedCrossRefGoogle Scholar
  3. 3.
    D.V. Santi, C.S. McHenry, and H. Sommer, Mechanism of Interaction of Thymidylate Synthetase with 5-Fluorodeoxyuridylate. Biochem. 13: 471 (1974).CrossRefGoogle Scholar
  4. 4.
    B. Ullman, M. Lee, D.W. Martin, and D.V. Santi, Cytotoxicity of 5-Fluoro-2’-Deoxyuridine: Requirement for Reduced Folate Cofactors and Antagonism by Methotrexate. Proc. Natl. Acad. Sci. 75: 980 (1978).PubMedCrossRefGoogle Scholar
  5. 5.
    R.M. Evans, J.D. Laskin, M.T. Hakala, Effects of Excess Folates and Deoxyinosine on the Activity of and Site of Action of 5Fluorouracil, Cancer Res. 41: 3288 (1981).PubMedGoogle Scholar
  6. 6.
    J.A. Houghton, S.J. Maroda, J.O. Phillips, and P.J. Houghton, Biochemical Determinants of Responsiveness to 5-Fluorouracil and its Derivatives in Xenografts of Human Colorectal Adenocarcinomas in Mice, Cancer Res. 41: 144 (1981).PubMedGoogle Scholar
  7. 7.
    D.G. Priest, M.T. Doig, and M. Mangum, Response of Mouse Hepatoma Cell Methylenetetrahydrofolate Polyglutamates to Folate Deprivation, Biochim. Biophys. Acta 756: 253 (1983).PubMedCrossRefGoogle Scholar
  8. 8.
    R.B. Livingston, and S. Carter, Single Agents in Cancer Chemotherapy. Plenum, New York, 1970, pp. 195–256.CrossRefGoogle Scholar
  9. 9.
    H.L. Davis, Chemotherapy of Large Bowel Cancer. Cancer 50: 2638 (1982).PubMedCrossRefGoogle Scholar
  10. 10.
    D. Machover, L. Schwarzenberg, E. Goldschmidt, J.M. Tourane, B. Michalski, M. Hatat, T. Dorval, J.L. Misset, C. Jasmin, R. Maral, and G. Mathe’, Treatment of Advanced Colorectal and Gastric Adenocarcinomas with 5-Fluorouracil Combined with High-Dose Folinic Acid: A Pilot Study. Cancer Treatment Rep. 66: 1803 (1982).Google Scholar
  11. 11.
    J.C. Grem, D.F. Hoth, J.M. Hamilton, S.A. King, and B. Leyland-Jones, Overview of Current Status and Future Direction of Clinical Trials with 5-Fluorouracil in Combination with Folinic Acid, Cancer Treatment Rep. 71: 1241 (1987).Google Scholar
  12. 12.
    P. Klubes, I. Cerna, and M.A. Meldon, Effect of Concurrent Calcium Leucovorin Infusion on 5-Fluorouracil Cytotoxicity Against Murine L1210 Leukemia, Cancer Chemother. Pharmacol. 6: 121 (1981).PubMedCrossRefGoogle Scholar
  13. 13.
    D.S. Duch, S.W. Bowers, and C.A. Nichol, Analysis of Cofactor Levels in Tissues Using High Performance Liquid Chromatography, Anal. Biochem. 130: 385 (1983).PubMedCrossRefGoogle Scholar
  14. 14.
    C.K. Mathews, and F.M. Huennekens, Enzymatic Preparation of the (1)-Diastereoisomers of Tetrahydrofolic Acid, J. Biol. Chem. 235: 3304 (1960).PubMedGoogle Scholar
  15. 15.
    D.W. Horne, C.L. Krumdieck, and C. Wagner, Properties of Folic Acid Gamma-Glutamyl Hyrolase (Conjugase) in Rat Bile and Plasma. J. Nutr. 111: 442 (1981).PubMedGoogle Scholar
  16. 16.
    R. Bertrand, R.E. MacKenzie, and J. Jolivet, Human Liver Methenyltetrahydrofolate Synthetase: Improved Purification and Increased Affinity for Folate Polyglutamate Substrates, Biochem. Biophys. Acta. 911: 154 (1987).PubMedCrossRefGoogle Scholar
  17. 17.
    P.K. Smith, R.I. Krohn, G.T. Hermanson, A.R. Mallia, F.H. Gartner, E.R. Provenzano, E.R. Fujimoto, N.M. Goeke, B.J. Olson, and D.C. Klenk, Measurement of Protein Using Bicinchoninic, Acid. Anal. Biochem. 150: 76 (1985).CrossRefGoogle Scholar
  18. 18.
    N.R. Meija, and R.E. MacKenzie, NAD-Dependent Methylenetetrahydrofolate Dehydrogenase Is Expressed by Immortal Cells, J. Biol. Chem. 260: 14616 (1985).Google Scholar
  19. 19.
    M. Trotz, C. Wegner, and H. Nau, Valproic Acid-Induced Neural Tube Defects: Reduction by Folinic Acid in the Mouse, Life Sci. 41: 103 (1987).PubMedCrossRefGoogle Scholar
  20. 20.
    J.A. Straw, D. Szapary, and W.T. Wynn, Pharmacokinetics of the Diastereoisomers of Leucovorin after Intravenous and Oral Administration to Normal Subjects, Cancer Res. 44: 3114 (1984).PubMedGoogle Scholar
  21. 21.
    B. McGuire, L. Sia, P. Leese, M. Gutierrez, and E.L.R. Stokstad, Pharmacokinetics of Leucovorin Calcium Given Intravenously, Intramuscularly, and Orally to Human Subjects, In NCI Monograph “Development of Folates and Folic Acid Antagonists in Cancer Chemotherapy”, p. 47, (1987).Google Scholar
  22. 22.
    F.M. Sirotnak, P.L. Chello, D.M. Moccio, R.L. Kisluk, G. Combepine, Y. Gaumont, and J.A. Montgomery, Stereospecificity at Carbon 6 of Formyltetrahydrofolate as a Competitive Inhibitor of Transport and Cytotoxicity of Methotrexate in vitro, Biochem. Pharmacol. 28: 2993 (1979).PubMedCrossRefGoogle Scholar
  23. 23.
    P.L. Chello, F.M. Sirotnak, E. Wong, R.L. Kisliuk, Y. Gaumont, and G. Combepine, Further Studies of Stereospecificity at Carbon 6 for Membrane Transport of Tetrahydrofolates, Biochem. Pharmacol. 31: 1527 (1982).PubMedCrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1988

Authors and Affiliations

  • Robert J. Mullin
    • 1
  • Barry R. Keith
    • 1
  • David S. Duch
    • 1
  1. 1.Department of Medicinal Biochemistry, Wellcome Research LaboratoriesResearch Triangle ParkUSA

Personalised recommendations