Metabolism of 5-fluorouracil in various human normal and tumor tissues

The metabolism of 5-fluorouracil (5-FU) in tumors and normal tissues of humans was investigated in vitro. Phosphorylation of 5-FU was faster in tumor tissues than in normal tissues. Phosphorylating activity with 2-deoxy-alpha-D-ribose 1-phosphate (dRiblP) and ATP as cofactors was more active than that with alpha D-ribose 1-phosphate (RiblP) and ATP, or 5-phospho-alpha-D-ribosyldiphosphate (PPRibP) as cofactors. Phosphorylating activity in squamous cell carcinoma of the lung was similar to that in adenocarcinomas. Degradation of 5-FU was much faster in the liver than in other tissues including tumor tissues.