[Metabolism of 1-(2-tetrahydrofuryl)-5-fluorouracil (FT-207) in human maxillary cancer (OKK) cells in culture].

Incubation of FT-207 with cytosol obtained from OKK cells but not from HEPM cells in vitro resulted in marked formation of the active metabolite, 5-FU. Degradation of 5-FU measured by FBA formation was very low in OKK cytosol but high in HEPM cytosol. High activity of 5-FU formation and low activity of 5-FU degradation in tumor cells might be responsible for increased 5-FU levels in the tumors of patients. Inhibition of OKK cell growth by FT-207 occurred in parallel with an appearance of 5-FU in the nucleus. We presume that a factor present in OKK cytosol is a soluble enzyme.