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Critical Reviews™ in Oncogenesis
SJR: 0.946 SNIP: 0.503 CiteScore™: 2

ISSN Print: 0893-9675
ISSN Online: 2162-6448

Critical Reviews™ in Oncogenesis

DOI: 10.1615/CritRevOncog.v12.i1-2.60
pages 115-126

Methyl-Group Metabolism and the Response of Colorectal Cancer to 5-Fluorouracil

Barry Iacopetta
School of Surgery and Pathology, University of Western Australia, Nedlands 6009, Australia


The major mechanism of action of 5-fluorouracil (5FU)-based therapies is thought to be inhibition of thymidylate synthase (TS). This enzyme catalyzes synthesis of the thymidine nucleotide precursor using a methyl group provided by a folate cofactor. In addition to TS activity levels, various elements of methyl-group metabolism could also be predictive for the response of colorectal cancer (CRC) to 5FU. These include the activity of enzymes involved in folate metabolism, the concentrations of intracellular folate intermediates, and surrogate markers of aberrant methyl-group metabolism, such as DNA methylation and microsatellite instability. The factors of age, gender, common genetic variants, and diet have been shown to influence both systemic and tumor methyl-group metabolism. This has important implications for the prediction of toxicity and response to 5FU, respectively. Identification of predictive factors within the methyl-group metabolism pathway should assist in targeting 5FU treatment to the most responsive CRC patient groups. This is particularly important for early-stage disease where conclusive demonstration of a survival benefit from 5FU in the overall CRC group has thus far proven difficult.