Saurabh Singh1, Robert M Greene, M Michele Pisano. 1. University of Louisville Birth Defects Center, Department of Molecular, Cellular and Craniofacial Biology, ULSD, Louisville, Kentucky 40292, USA.
Abstract
BACKGROUND: Arsenic is a ubiquitous element that is a potential carcinogen and teratogen and can cause adverse developmental outcomes. Arsenic exerts its toxic effects through the generation of reactive oxygen species (ROS) that include hydrogen peroxide (H(2)O(2)), superoxide-derived hydroxyl ion, and peroxyl radicals. However, the molecular mechanisms by which arsenic induces cytotoxicity in murine embryonic maxillary mesenchymal (MEMM) cells are undefined. METHODS: MEMM cells in culture were treated with different concentrations of pentavalent sodium arsenate [As (V)] for 24 or 48 hr and various end points measured. RESULTS: Treatment of MEMM cells with the pentavalent form of inorganic arsenic resulted in caspase-mediated apoptosis, accompanied by generation of ROS and disruption of mitochondrial membrane potential. Treatment with caspase inhibitors markedly blocked apoptosis. In addition, the free radical scavenger N-acetylcysteine dramatically attenuated arsenic-mediated ROS production and apoptosis, and exposure to arsenate increased Bax and decreased Bcl protein levels in MEMM cells. CONCLUSIONS: Taken together, these findings suggest that in MEMM cells arsenate-mediated oxidative injury acts as an early and upstream initiator of the cell death cascade, triggering cytotoxicity, mitochondrial dysfunction, altered Bcl/Bax protein ratios, and activation of caspase-9. Copyright 2009 Wiley-Liss, Inc.
BACKGROUND:Arsenic is a ubiquitous element that is a potential carcinogen and teratogen and can cause adverse developmental outcomes. Arsenic exerts its toxic effects through the generation of reactive oxygen species (ROS) that include hydrogen peroxide (H(2)O(2)), superoxide-derived hydroxyl ion, and peroxyl radicals. However, the molecular mechanisms by which arsenic induces cytotoxicity in murineembryonic maxillary mesenchymal (MEMM) cells are undefined. METHODS: MEMM cells in culture were treated with different concentrations of pentavalent sodium arsenate [As (V)] for 24 or 48 hr and various end points measured. RESULTS: Treatment of MEMM cells with the pentavalent form of inorganic arsenic resulted in caspase-mediated apoptosis, accompanied by generation of ROS and disruption of mitochondrial membrane potential. Treatment with caspase inhibitors markedly blocked apoptosis. In addition, the free radical scavenger N-acetylcysteine dramatically attenuated arsenic-mediated ROS production and apoptosis, and exposure to arsenate increased Bax and decreased Bcl protein levels in MEMM cells. CONCLUSIONS: Taken together, these findings suggest that in MEMM cells arsenate-mediated oxidative injury acts as an early and upstream initiator of the cell death cascade, triggering cytotoxicity, mitochondrial dysfunction, altered Bcl/Bax protein ratios, and activation of caspase-9. Copyright 2009 Wiley-Liss, Inc.
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