title: Conversion of 6-mercaptopurine to 6-thioguanylic acid in L-1210 cells and human leukemia cells.
abstract: The metabolism of 6-mercaptopurine (6-MP) in L-1210 mouse leukemia cells and human chronic myelocytic leukemia cells (CML cells) was examined. The acid-soluble fractions obtained from cells incubated with [8-14C]6-MP were chromatographed on a Dowex-1 formate resin column using a formic acid linear gradient elution system. Chromatography of the extract of L-1210 cells revealed four principal radioactive peaks. The fraction containing the third peak was hydrolyzed by snake venom 5'-nucleotidase (Crotalus adamanteus). Cellulose thin layer chromatography revealed that the radioactive peak of the hydrolysate corresponded to 6-thioguanosine. The results showed that 6-MP was converted to 6-thioinosinic acid (6-TIMP) and 6-thioguanylic acid (6-TGMP) in L-1210 cells. In order to elucidate the pathway of 6-MP conversion to 6-TGMP, we examined the interaction of [8-14C]6-TIMP and purified IMP dehydrogenase. It was found by DEAE-cellulose thin layer chromatography that the IMP dehydrogenase converted 6-TIMP to 6-thioxanthylic acid (6-TXMP). Dowex-1 chromatography of the acid-soluble extract of human CML cells incubated with [8-14C]-6-MP also revealed a radioactive peak corresponding to 6-TGMP. These results suggest that 6-MP is metabolized to 6-TGMP by serial conversion to 6-TIMP and 6-TXMP through the de novo GMP synthetic pathway in L-1210 cells and human CML cells.
authors.forename: M
authors.initials: M
authors.lastname: Uchida
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: H
authors.initials: H
authors.lastname: Uchino
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002845:Chromatography; D002848:Chromatography, DEAE-Cellulose; D006150:Guanine Nucleotides / Q000032:analysis*; D006151:Guanosine / Q000031:analogs & derivatives / Q000378:metabolism; D006801:Humans; D007168:IMP Dehydrogenase / Q000302:isolation & purification; D007700:Kinetics; D007939:Leukemia L1210 / Q000378:metabolism*; D007951:Leukemia, Myeloid / Q000378:metabolism*; D015122:Mercaptopurine / Q000378:metabolism*; D051379:Mice; D013872:Thionucleosides / Q000378:metabolism; D013873:Thionucleotides / Q000032:analysis*
chemical_list: D006150:Guanine Nucleotides; D013872:Thionucleosides; D013873:Thionucleotides; D006151:Guanosine; C003964:6-thioguanylic acid; C005783:6-thioguanosine; D015122:Mercaptopurine; D007168:IMP Dehydrogenase