Effect of methotrexate on 5-phosphoribosyl 1 pyrophosphate levels in L1210 leukemia cells in vitro

摘要: Abstract The cellular content of 5-phosphoribosyl 1-pyrophosphate (PRPP) and PRPP synthetase activity levels was examined in cultured L1210 mouse leukemia cells after exposure to methotrexate (MTX). determined cold perchloric acid extracts using a radiochemical method measuring the conversion [14C]adenine [14C]adenosine 5′-monophosphate presence added adenine phosphoribosyltransferase activity. measured dialyzed cell-free by coupled enzyme assay determining production reaction. intracellular untreated during logarithmic growth varied over 24 hr with mean 145 ± 65 (S.D.) pmol/106 cells. Treatment 1 μm MTX caused an increase 1.5 3 maximal 5- 10-fold higher than controls. Elevated persisted for up 12 declined control values hr. Similar results were obtained 0.1 MTX, while 0.01 more gradual which at maintained least additional addition mm hypoxanthine led recovery elevated exposed but not 10 No large difference between MTX-treated observed. indicate that leads increased PRPP, probably due decreased utilization de novo purine synthesis as result synthesis. Enhanced are available reutilization preformed purines; however, afterwards only partially replenished prolonged drug because capacity despite continued