Nakadai Ari, Li Qing, Kawada Tomoyuki
Department of Hygiene and Public Health, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan.
Toxicology. 2006 Jul 25;224(3):202-9. doi: 10.1016/j.tox.2006.04.055. Epub 2006 May 9.
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.
为了研究毒死蜱诱导人免疫细胞死亡及其潜在机制，将人单核细胞样细胞系（U937）在37摄氏度、5%二氧化碳培养箱中用4.45 - 570微摩尔的毒死蜱处理0.5 - 24小时。我们首先发现，如通过乳酸脱氢酶（LDH）和MTT检测以及碘化丙啶（PI）摄取所示，毒死蜱以剂量和时间依赖性方式诱导U937细胞死亡。然后，我们通过流式细胞术分析膜联蛋白V染色和细胞内活性半胱天冬酶 - 3水平以及DNA片段化分析，研究毒死蜱诱导的细胞死亡是否包括凋亡。我们发现，如膜联蛋白V染色所示，毒死蜱以时间和剂量依赖性方式诱导U937细胞凋亡。当细胞用71至284微摩尔的毒死蜱处理4或6小时时，检测到DNA片段化。毒死蜱还以剂量依赖性方式诱导U937细胞内活性半胱天冬酶 - 3增加，并且半胱天冬酶 - 3抑制剂Z - DEVD - FMK显著抑制毒死蜱诱导的凋亡。这些发现表明，毒死蜱可诱导U937细胞凋亡，并且这种作用部分由细胞内半胱天冬酶 - 3的激活介导。
