[Effect of 5-FU on the utilization of purine and pyrimidine by human gastric cancer cells (KATO III)].

Effect of utilization of purine and pyrimidine in the culture medium by human gastric cancer cells (KATO III) was evaluated. Nucleosides mixture solution (OG-VI), consisting of inosine, guanosine 5' monophosphate (5'GMP), cytidine, uridine and thymidine (4: 4: 4: 3: 1 in molar ratio) was used and their levels in the culture medium was measured by HPLC after 3 day culture. Purine, inosine and 5' GMP, in the medium almost decreased and purine base, xanthine and hypoxanthine levels increased, but changes in pyrimidine level were minimal. 5-FU decreased purine and increased pyrimidine consumption. Addition of nucleosides mixture did not enhance the cellular proliferation, but inhibited growth when given in higher concentrations. Nucleoside mixture solution enhanced growth inhibition by 5-FU and it is a potential biochemical modulator of 5-FU metabolism in human cancer cells.