Increased concentrations of methylated 6-mercaptopurine metabolites and 6-thioguanine nucleotides in human leukemic cells in vitro by methotrexate.
Biochem Pharmacol
; 55(10): 1641-6, 1998 May 15.
Article
en En
| MEDLINE
| ID: mdl-9634000
The effect of methotrexate (MTX) on 6-mercaptopurine (6-MP) metabolism was studied in four human leukemic cell lines in vitro. CCRF-CEM, WI-L2, TBJ, and HL-60 all expressed thiopurine methyltransferase (TPMT) activity. The cells were grown in horse serum-supplemented RPMI 1640 medium to which was added 4 microM of 6-MP or 4 microM of 6-MP and 20 nM of MTX. The presence of MTX resulted in a 2.1-, 1.7-, 2.4- and 8-fold increase in the concentrations of methylmercaptopurine ribonucleotides (MMPRP) in CEM, WI-L2, TBJ, and HL-60 cells, respectively (P < 0.0008). The concentrations of 6-thioguanine nucleotides (6 TGN) increased 1.9-, 1.4-, 2.4- and 1.9-fold in the same cell lines (P < 0.02). The four cell lines differed with respect to the effect of MTX on the consumption of 6-MP from the medium; CEM consumed more 6-MP and WI-L2 less 6-MP from media containing MTX than from media containing 6-MP only (P = 0.005 and 0.02, respectively). MTX did not affect the consumption of 6-MP by TBJ cells (P = 0.17). Media in which HL-60 cells had been grown did not contain detectable amounts of 6-MP at the end of the experiment. The simultaneous increase in methylated 6-MP metabolites and 6-TGN represents a possible explanation for the synergism of MTX and 6-MP; however, the clinical importance of increased MMPRP remains to be elucidated.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Tioguanina
/
Metotrexato
/
Nucleótidos de Guanina
/
Mercaptopurina
Límite:
Humans
Idioma:
En
Revista:
Biochem Pharmacol
Año:
1998
Tipo del documento:
Article
País de afiliación:
Noruega
Pais de publicación:
Reino Unido