title: N-t-Butyl hydroxylamine regulates ionizing radiation-induced apoptosis in U937 cells.
abstract: Ionizing radiation induces the production of reactive oxygen species, which play an important causative role in apoptotic cell death. Therefore, compounds that scavenge reactive oxygen species may confer regulatory effects on apoptosis. Recently, it has been shown that the decomposition product of the spin-trapping agent alpha-phenyl-N-t-butylnitrone, N-t-butyl hydroxylamine (NtBHA), mimics alpha-phenyl-N-t-butylnitrone and is much more potent in delaying reactive oxygen species-associated senescence. We investigated the effects of NtBHA on ionizing radiation-induced apoptosis. Upon exposure to 2Gy of gamma-irradiation, there was a distinct difference between the control cells and the cells pre-treated with 0.1mM NtBHA for 2h in regard to apoptotic parameters, cellular redox status, mitochondria function, and oxidative damage to cells. NtBHA effectively suppressed morphological evidence of apoptosis and DNA fragmentation in U937 cells exposed to ionizing radiation. The generation of intracellular reactive oxygen species was higher and the GSH level was lower in control cells compared to NtBHA-treated cells. The ionizing radiation-induced mitochondrial damage reflected by the altered mitochondrial permeability transition, the increase in the accumulation of reactive oxygen species, and the reduction of ATP production were significantly higher in control cells compared to NtBHA-treated cells. NtBHA pre-treated cells showed significant inhibition of apoptotic features such as activation of caspase-3, up-regulation of Bax and p53, and down-regulation of Bcl-2 compared to control cells upon exposure to ionizing radiation. This study indicates that NtBHA may play an important role in regulating the apoptosis induced by ionizing radiation presumably through scavenging of reactive oxygen species.
authors.affiliation: School of Life Sciences and Biotechnology, College of Natural Sciences, Kyungpook National University, Taegu 702-701, Republic of Korea.
authors.forename: Jin Hyup
authors.initials: JH
authors.lastname: Lee
authors.forename: Jean Kyoung
authors.initials: JK
authors.lastname: Tak
authors.forename: Kwon Moo
authors.initials: KM
authors.lastname: Park
authors.forename: Jeen-Woo
authors.initials: JW
authors.lastname: Park
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects*; D061945:Caspase Inhibitors; D053938:DNA Fragmentation / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D005720:Gamma Rays; D005786:Gene Expression Regulation; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D006898:Hydroxylamines / Q000494:pharmacology*; D008928:Mitochondria / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D013113:Spin Labels; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D020298:U937 Cells; D015854:Up-Regulation / Q000187:drug effects; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: C494826:BAX protein, human; D061945:Caspase Inhibitors; D006898:Hydroxylamines; D017382:Reactive Oxygen Species; D013113:Spin Labels; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D000255:Adenosine Triphosphate; D005978:Glutathione