THE FORMATION OF 6-MERCAPTOPURINE RIBOSIDE PHOSPHATE IN ASCITES TUMOR CELLS

Abstract

A nucleotide metabolite of 6-mercaptopurine has been isolated from Erhlich ascites carcinoma cells exposed to this compound under in vivo and in vitro conditions. By chemical and enzymatic methods, this nucleotide has been identified as 6-mercaptopurine nucleoside-5′-monophosphate.6-Mercaptopurine nucleotide is formed rapidly in the tumor cells in vivo, maximum concentrations being achieved within 0.5 hours after administration of the analogue. Treatment of the tumor cells with 6-mercaptopurine or with azaserine induced a twofold to threefold enhancement in their ability to synthesize 6-mercaptopurine nucleotide.Using isotopic techniques small amounts of 6-mercaptopurine nucleotide were detected in liver, intestine, and a solid tumor. The conversion of 6-mercaptopurine to the nucleotide form was also demonstrated in an ascitic form of Sarcoma 180.