Methylenetetrahydrofolate reductase (MTHFR) variants and fluorouracil-based treatments in colorectal cancer.
5-fluorouracil (5FU)-based treatments remain the main chemotherapy for colorectal cancer. Optimal cytotoxicity of fluoropyrimidines requires elevated CH(2)FH(4) tumoral concentrations, controlled by the methylenetetrahydrofolate reductase (MTHFR) enzyme, which irreversibly converts CH(2)FH(4) into 5-methyltetrahydrofolate. The MTHFR gene is subject to several polymorphisms, of which the 677C>T and 1298A>C SNPs are the two most commonly linked with altered enzyme activity. Since a drop in MTHFR enzymatic activity may theoretically favor an increase in intracellular CH(2)FH(4) concentrations, it can be hypothesized that tumors exhibiting the rare MTHFR variants may be more sensitive to 5FU cytotoxicity. Accordingly, experimental data have shown that rare MTHFR variants in position 677 and 1298 are more sensitive to 5FU. However, results of clinical data do not concord regarding the influence of MTHFR genotype on tumoral CH(2)FH(4) concentration, 5FU responsiveness, patient survival and 5FU-related toxicity. These discrepancies may result from the interpatient variability arising from the individual folate status, as well as from the limited role of fluoropyrimidines in the current chemotherapy regimen administered in colorectal cancer.
Centre Antoine Lacassagne, Oncopharmacology Unit, 33 Avenue de Valombrose, 06189 Nice Cedex 2, France. marie-christine.etienne@nice.fnclcc.fr
Marie-Christine
MC
Etienne-Grimaldi
Mireille
M
Francoual
Jean-Louis
JL
Formento
Gérard
G
Milano
D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use; D001711:Biotransformation / Q000235:genetics; D002986:Clinical Trials as Topic; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000401:mortality; D005472:Fluorouracil / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use; D014644:Genetic Variation; D006801:Humans; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics* / Q000378:metabolism; D013763:Tetrahydrofolates / Q000378:metabolism
D000964:Antimetabolites, Antineoplastic; D013763:Tetrahydrofolates; D042965:Methylenetetrahydrofolate Reductase (NADPH2); C005984:5-methyltetrahydrofolate; D005472:Fluorouracil