Hydrogen peroxide-induced apoptosis of HL-60 human leukemia cells is mediated by the oxidants hypochlorous acid and chloramines.
We set out to identify whether HOCl, which is generated from H(2)O(2) /MPO/Cl(-), is a proximal mediator of H(2)O(2) programmed cell death in the HL-60 human leukemia cell. We found that authentic HOCl induces apoptosis in the HL-60 cell. Both the addition of methionine, an HOCl scavenger, and the removal of Cl(-) from the medium to prevent the formation of HOCl inhibited H(2)O(2)-induced apoptosis. HL-60 cells underwent apoptosis when exposed to HOCl in full medium, which gives rise to chloramines by the reaction of HOCl with amine groups, but not by HOCl in the amine-free HBSS, in which HOCl but not chloramines can be detected. Authentic chloramines induced apoptosis in this cell line in a concentration-dependent manner and at concentrations lower than HOCl. Full medium exposed to HOCl for 24 h would support methionine noninhibitable apoptosis, but did not react with 2-nitro-5-thiobenzoic acid (TNB), raising the possibility that the final inducer is a nonoxidant formed from HOCl and chloramines. We conclude that the signal for apoptosis induced by H(2)O(2) in the MPO-containing HL-60 cell involves the reaction of the diffusible oxidant HOCl with amines producing chloramines and a subsequent non-TNB-reactive product.
Wagner
Brett A
BA
Department of Medicine and Radiation Oncology (Free Radical and Radiation Biology Graduate Program), The University of Iowa College of Medicine, Iowa City, IA 52242, USA.
Britigan
Bradley E
BE
Reszka
Krzysztof J
KJ
McCormick
Michael L
ML
Burns
C Patrick
CP
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002700:Chloramines / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism; D003470:Culture Media; D018922:HL-60 Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D006997:Hypochlorous Acid / Q000378:metabolism*; D008715:Methionine / Q000494:pharmacology; D008954:Models, Biological; D009336:Necrosis; D009579:Nitrobenzoates / Q000378:metabolism; D016877:Oxidants / Q000378:metabolism; D013438:Sulfhydryl Compounds
D002700:Chloramines; D002712:Chlorides; D003470:Culture Media; D009579:Nitrobenzoates; D016877:Oxidants; D013438:Sulfhydryl Compounds; C011136:thionitrobenzoic acid; D006997:Hypochlorous Acid; D008715:Methionine; D006861:Hydrogen Peroxide