title: Chlorpyrifos induces apoptosis in human monocyte cell line U937.
abstract: In order to investigate chlorpyrifos-induced cell death and its underlying mechanism in human immune cells, a human monocyte like cell line (U937) was treated with chlorpyrifos at 4.45-570microM for 0.5-24h at 37 degrees Celsius in a 5% CO(2) incubator. We first found that chlorpyrifos induced cell death of U937 in a dose- and time-dependent manner, as shown by LDH and MTT assays and PI uptake. Then, we investigated if chlorpyrifos-induced cell death consisted of apoptosis, as determined by analysis of Annexin-V staining and the intracellular level of active caspase-3 by flow cytometry, and DNA fragmentation analysis. We found that chlorpyrifos induced apoptosis in U937 in a time- and dose-dependent manner, as shown by Annexin-V staining. DNA fragmentation was detected when cells were treated with 71 to 284microM chlorpyrifos for 4 or 6h. Chlorpyrifos also induced an increase of intracellular active caspase-3 in U937 cells in a dose-dependent manner, and a caspase-3 inhibitor, Z-DEVD-FMK, significantly inhibited the chlorpyrifos-induced apoptosis. These findings indicate that chlorpyrifos can induce apoptosis in U937 cells, and this effect is partially mediated by activation of intracellular caspase-3.
authors.affiliation: Department of Hygiene and Public Health, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan.
authors.forename: Ari
authors.initials: A
authors.lastname: Nakadai
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Kawada
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D004390:Chlorpyrifos / Q000494:pharmacology*; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004950:Esterases / Q000494:pharmacology; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D007306:Insecticides / Q000494:pharmacology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009842:Oligopeptides / Q000494:pharmacology; D013997:Time Factors; D020298:U937 Cells
chemical_list: D061945:Caspase Inhibitors; D002800:Cholinesterase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D007306:Insecticides; D009842:Oligopeptides; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; D007770:L-Lactate Dehydrogenase; D004950:Esterases; C107247:chlorpyrifos-oxonase; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D004390:Chlorpyrifos