Abstract
The uracil analog 5-fluorouracil (5-FU) is used as part of combination therapy for the treatment of breast, head/neck, and gastrointestinal malignancies, and has single-agent activity in colorectal cancer. 5-FU itself is inactive and requires intracellular conversion to form cytotoxic nucleotides (1). Several cellular targets for fluoropyrimidines have been well-characterized, including inhibition of thymidylate synthase (TS) by fluorodeoxyuridine monophosphate (FdUMP) and false base incorporation into RNA or DNA. Most investigations into cellular resistance factors regulating 5-FU activity have focused on alterations in (TS) levels and reduced folate pools, the required cofactor for binding dUMP to thymidylate synthase (1). However, the majority of an administered 5-FU dose undergoes metabolism to inactive species through a three-enzyme process, which is initiated and rate-limited by dihydropyrimidine dehydrogenase (DPD; EC 1.3.1.2). Following a bolus injection of 5-FU, 80% is degraded via DPD after 24 h after administration (2). Studies of 19F nuclear magnetic resonance (NMR) spectroscopy in mice bearing colon tumors found catabolites made up 51% of labeled drug in the tumor, compared with 26% for the anabolic products (3).
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsSpringer Nature is developing a new tool to find and evaluate Protocols. Learn more
References
Pinedo, H. M. and Peters, G. J. (1988) Fluorouracil: biochemistry and pharmacology. J. Clin. Oncol. 6, 1653–1664.
McMurrough, J. and McLeod, H. L. (1996) Analysis of the dihydropyrimidine dehydrogenase polymorphism in a British population. Br. J. Clin. Pharmacol. 41, 425–427.
Kamm, Y. J. L., Rietjens, I. M. C., Vervoort, J., Heerschap, A., Rosenbusch, G., Hofs, H. P., and Wagener, D. J. T. (1994). Effect of modulators on 5-fluorouracil metabolite patterns in murine colon carcinoma determined by in vitro 19F nuclear magnetic resonance spectroscopy. Cancer Res. 54, 4321–4326.
Wei, X., McLeod, H. L., McMurrough, J., Gonzalez, F. J., and Fernandez-Salguero, P. (1996) Molecular basis for the human dihydropyrimidine dehydrogenase deficiency and 5-FU toxicity. J. Clin. Invest. 98, 610–615.
Gonzalez, F. J. and Fernandez-Salguero, P. (1995) Diagnostic analysis, clinical importance and molecular basis of dihydropyrimidine dehydrogenase deficiency. Trends Pharmacol. Sci. 16, 325–327.
McLeod, H. L., Sludden, J., Murray, G. I., Keenan, R. A., Davidson, A. I., Park, K., Koruth, M., and Cassidy, J. (1998) Characterisation of dihydropyrimidine dehydrogenase in human colorectal tumors. Br. J. Cancer 77, 461–465.
Sludden, J., Hardy, S. C., VandenBranden, M. R., Wrighton, S. A., and McLeod, H. L. (1998) Liver dihydropyrimidine dehydrogenase activity in human, cynomolgus monkey, rhesus monkey, dog, rat, and mouse. Pharmacology 56, 276–280.
Makower, D., Wadler, S., Haynes, H., and Schwartz, E. L. (1997) Interferon induces thymidine phosphorylase/platelet-derived endothelial cell growth factor expression in vivo. Clin. Cancer Res. 3, 923–929.
Folkman, J., (1996) What is the role of thymidine phosphorylase in tumor angiogenesis? J. Nat. Cancer Inst. 88, 1091–1092.
Takebayashi, Y., Akiyama, S., Akiba, S., Yamada, K., Miyadera, K., Sumizawa, T., Yamada, Y., Murata, F., and Aikou, T. (1996) Clinicopathological and prognostic significance of an angiogenic factor, thymidine phosphorylase, in human colorectal carcinoma. J. Nat. Cancer Inst. 88, 1110–1117
Peters, G. J., Vangroeningen, C. J., Laurensse, E. J., and Pinedo, H. M. (1991) A comparison of 5-fluorouracil metabolism in human colorectal cancer and colon mucosa. Cancer 68, 1903–1909.
Friedkin, M. and Roberts, D. (1954) The enzymatic synthesis of nucleosides. I. Thymidine phosphorylase in mammalian tissue. J. Biol. Chem. 297, 245–256.
Patterson, A. V., Zhang, H., Moghaddam, A., Bicknell, R., Talbot, D. C., Stratford, I. J., and Harris, A. L. (1995) Increased sensitivity to the prodrug 5′-deoxy-5-fluorouridine and modulation of 5-fluoro-2′-deoxyuridine sensitivity in MCF-7 cells transfected with thymidine phosphorylase. Br. J. Cancer 72, 669–675.
Gan, T. E., Hallam, L., Pilkington, G. R., and Vanderweyden, M. B. (1981) A rapid and simple radiometric assay for thymidine phosphorylase of human peripheral blood cells. Clin. Chim. Acta 116, 231–236.
Milne, L. H., Blackie, R. G., Twelves, C., and McLeod, H. L. A sensitive and automated assay for thymidine phosphorylase activity (submitted).
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 1999 Humana Press Inc.
About this protocol
Cite this protocol
McLeod, H.L., Milne, L.H., Johnston, S.J. (1999). 5-Fluorouracil Metabolizing Enzymes. In: Brown, R., Böger-Brown, U. (eds) Cytotoxic Drug Resistance Mechanisms. Methods in Molecular Medicine™, vol 28. Humana Press. https://doi.org/10.1385/1-59259-687-8:111
Download citation
DOI: https://doi.org/10.1385/1-59259-687-8:111
Publisher Name: Humana Press
Print ISBN: 978-0-89603-603-1
Online ISBN: 978-1-59259-687-4
eBook Packages: Springer Protocols