title: Mechanism of ziram-induced apoptosis in human T lymphocytes.
abstract: Ziram as a dithiocarbamate fungicide is widely used throughout the world in agriculture. We previously found that ziram significantly inhibited cytotoxic T lymphocyte activity in a dose-dependent manner. To explore the mechanism of this inhibition, we investigated ziram-induced apoptosis in human T lymphocytes. Jurkat T cells were treated with ziram at 0.031-1 μM for 2-24 h. Freshly isolated primary human T cells were treated with ziram at 0.0625-1 μM for 15 and 24 h. Apoptosis was determined by FITC-Annexin V/PI staining and the TUNEL assay. 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. We found that ziram induced apoptosis in a time- and dose-dependent manner in both Jurkat cells and primary human T cells. The primary human T cells were more sensitive to ziram than the Jurkat cell line. Ziram induced increases in active caspases 3, 3/7, 8, and 9 and pan-caspase in a dose-dependent manner, and a caspase-3 inhibitor, Z-DEVD-FMK, partially but significantly inhibited the apoptosis. Moreover, a general caspase inhibitor, Z-VAD-FMK, significantly and almost completely blocked the apoptosis. Ziram also disrupted mitochondrial transmembrane potential and caused mitochondrial cytochrome-c release. These findings indicate that ziram can induce apoptosis in human T cells, and the apoptosis is mediated by both the caspase-cascade and the mitochondria/cytochrome-c pathways.
authors.affiliation: Department of Hygiene and Public Health, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan. qing-li@nms.ac.jp
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
authors.forename: Maiko
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Kawada
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D020169:Caspases / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D005659:Fungicides, Industrial / Q000633:toxicity*; D006801:Humans; D019169:Jurkat Cells / Q000187:drug effects / Q000473:pathology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology; D009336:Necrosis / Q000139:chemically induced; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D015039:Ziram / Q000633:toxicity*
chemical_list: D005659:Fungicides, Industrial; D015039:Ziram; D045304:Cytochromes c; D020169:Caspases