A new mechanism of methotrexate action revealed by target screening with affinity beads.
Methotrexate (MTX) is the anticancer and antirheumatoid drug that is believed to block nucleotide synthesis and cell cycle by inhibiting dihydrofolate reductase activity. We have developed novel affinity matrices, termed SG beads, that are easy to manipulate and are compatible with surface functionalization. Using the matrices, here we present evidence that deoxycytidine kinase (dCK), an enzyme that acts in the salvage pathway of nucleotide biosynthesis, is another target of MTX. MTX modulates dCK activity differentially depending on substrate concentrations. 1-beta-D-Arabinofuranosylcytosine (ara-C), a chemotherapy agent often used in combination with MTX, is a nucleoside analog whose incorporation into chromosome requires prior phosphorylation by dCK. We show that, remarkably, MTX enhances incorporation and cytotoxicity of ara-C through regulation of dCK activity in Burkitt's lymphoma cells. Thus, this study provides new insight into the mechanisms underlying MTX actions and demonstrates the usefulness of the SG beads.
Uga
Hitoshi
H
Aphoenix Inc., Tokyo, Japan.
Kuramori
Chikanori
C
Ohta
Akiko
A
Tsuboi
Yasunori
Y
Tanaka
Hiroshi
H
Hatakeyama
Mamoru
M
Yamaguchi
Yuki
Y
Takahashi
Takashi
T
Kizaki
Masahiro
M
Handa
Hiroshi
H
D000595:Amino Acid Sequence; D001085:Arabinofuranosylcytosine Triphosphate / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002846:Chromatography, Affinity / Q000379:methods*; D002877:Chromosomes, Human / Q000235:genetics; D003842:Deoxycytidine Kinase / Q000737:chemistry / Q000302:isolation & purification; D004354:Drug Screening Assays, Antitumor / Q000295:instrumentation* / Q000379:methods*; D006801:Humans; D019169:Jurkat Cells; D008727:Methotrexate / Q000494:pharmacology*; D008863:Microspheres; D008969:Molecular Sequence Data; D008970:Molecular Weight; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism
D001085:Arabinofuranosylcytosine Triphosphate; D013762:Tetrahydrofolate Dehydrogenase; D003842:Deoxycytidine Kinase; D008727:Methotrexate