| Abstract |
Silver is commonly used as a disinfectant, and chronic exposure to silver may cause argyria, resulting in a gray-blue discoloration of human skin. However, the mechanism for cellular toxicity of silver has not been well explained. We studied the mode of cell death, the ratio of glutathione disulfide/glutathione, induction of metallothionein and activation of mitogen-activated protein kinases in J774.1 cells together with activation of antioxidant responsive element and nuclear factor-κB in CHO cells following exposure to silver ion (Ag+ ) to investigate the mechanism by which Ag+ causes lethal effects. Ag+ increased phosphorylation levels of extracellular signal-regulated, c-Jun N-terminal and p38 mitogen-activated protein kinases and remarkably increased the ratio of glutathione disulfide/glutathione in both a time- and concentration-dependent manner. Luciferase reporter gene assays revealed that antioxidant responsive element and nuclear factor-κB were activated following exposure to Ag+ . In addition, exposure to Ag+ increased the mRNA and protein levels of metallothionein. We investigated whether or not Ag+ killed J774.1 cells by inducing apoptosis. Ag+ increased the activity of caspase-3/7 which was abrogated by caspase 3 and pan-caspase inhibitors. However, these inhibitors did not ameliorate the cytotoxic effects of Ag+ , suggesting that Ag+ causes oxidative stress, which leads to necrotic rather than apoptotic cell death in J774.1 cells by decreasing functional sulfhydryl groups including glutathione in the cells. Copyright © 2016 John Wiley & Sons, Ltd.
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