title: Mechanism of ziram-induced apoptosis in human natural killer cells.
abstract: We previously found that ziram, a dithiocarbamate fungicide, significantly inhibited natural killer (NK) activity in a dose-dependent manner. To explore the mechanism of this inhibition, we investigated ziram-induced apoptosis in human NK cells. Human NK-92MI cells were treated with ziram at 0.0625-4 &#181;M for 2-64 h. Apoptosis was determined by FITC-Annexin-V/PI staining. To explore the mechanism of apoptosis, intracellular levels of active caspases 3, 3/7, 8, and 9 and pan-caspase and mitochondrial cytochrome-c release were determined by flow cytometry. Disruption to mitochondrial transmembrane potential was determined with a MitoLight? Apoptosis Detection Kit. It was found that ziram induced apoptosis in a dose- and time-dependent manner in human NK cells. Ziram increased the intracellular levels of active caspases 3, 3/7, 8, and 9 and pan-caspase in a dose-dependent manner, and a caspase-3 inhibitor, Z-DEVD-FMK, and a general caspase inhibitor, Z-VAD-FMK, partially but significantly inhibited the apoptosis. Ziram also disrupted mitochondrial transmembrane potential and caused mitochondrial cytochrome-c release in a dose-dependent manner. These findings indicate that ziram can induce apoptosis in human NK cells, and the apoptosis is at least mediated by both the caspase-cascade and the mitochondria/cytochrome-c pathways.
authors.affiliation: Department of Hygiene and Public Health, Nippon Medical School, Tokyo, Japan. qing-li@nms.ac.jp
authors.forename: Q
authors.initials: Q
authors.lastname: Li
authors.forename: M
authors.initials: M
authors.lastname: Kobayashi
authors.forename: T
authors.initials: T
authors.lastname: Kawada
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000032:analysis; D045744:Cell Line, Tumor; D045304:Cytochromes c / Q000378:metabolism; D005434:Flow Cytometry; D005659:Fungicides, Industrial / Q000494:pharmacology*; D006801:Humans; D007694:Killer Cells, Natural / Q000187:drug effects*; D053078:Membrane Potential, Mitochondrial; D009336:Necrosis; D015039:Ziram / Q000494:pharmacology*
chemical_list: D005659:Fungicides, Industrial; D015039:Ziram; D045304:Cytochromes c; D053148:Caspase 3