title: Tumor specific conversion of a pyrimidine antimetabolite.
abstract: In order to explain the high differences of activity of 5'-dFUR and FUdR in the 4 tumor lines the conversion rate of the 2 nucleosides to the cytotoxic metabolite 5-FU was measured and compared with the conversion rate of uridine to uracil in tumor and liver homogenates. High activity of pyrimidine nucleoside phosphorylase was found in 5'-dFUR-sensitive tumor tissues. Conversion rates of uridine and 5'-dFUR were much lower in 5'-dFUR-insensitive tumors and in normal liver. This might at least partially explain the different responses to 5'-dFUR in vivo and in vitro.
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism*; D002460:Cell Line; D005467:Floxuridine / Q000378:metabolism* / Q000627:therapeutic use; D005472:Fluorouracil / Q000627:therapeutic use; D007536:Isomerism; D051379:Mice; D009374:Neoplasms, Experimental / Q000188:drug therapy / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D005467:Floxuridine; D005472:Fluorouracil; C025034:doxifluridine