The Mechanism of Elevated Toxicity in HepG2 Cells Due to Combined Exposure to Ethanol and Ionizing Radiation
Ethanol and ionizing radiation exposure are independently known to cause tissue damage through various mechanisms. The non-enzymatic and enzymatic metabolism of ethanol, the latter via the cytochrome P(450) 2E1-dependent pathway produces free radicals, which deplete cellular glutathione (GSH). Ionizing radiation exposure has been shown to induce lipid peroxidation, DNA damage, protein oxidation and GSH depletion. It was postulated that cells sensitized by ethanol will be susceptible to additional insult, such as by radiation through increased oxidative stress. In this investigation, cultured liver cells (HepG2, human hepatocellular liver carcinoma) were exposed to ethanol, followed by ionizing radiation. The antioxidant status of the cells was evaluated by an array of techniques. Levels of glutathione, cysteine (CYS), and malondialdehyde (MDA) were measured by HPLC. Activities of antioxidant enzymes, catalase and glutathione reductase (GR) were determined enzymatically. Apoptosis was evaluated by the caspases-3 assay and fluorescence microscopy. The data showed that combined treatment with ethanol and radiation resulted in the lowest levels of GSH, and highest MDA level compared with the control. The catalase activity was lower in the combined exposure groups, when compared with the single agent exposure groups, and the glutathione reductase activity was the highest in the combined exposure groups and lowest in the control. These findings suggest that a combination of ethanol and ionizing radiation results in greater toxicity in vitro through elevated oxidative stress.
J. Ogony et al., "The Mechanism of Elevated Toxicity in HepG2 Cells Due to Combined Exposure to Ethanol and Ionizing Radiation," Journal of Applied Toxicology, no. 3, pp. 345-355, John Wiley & Sons, Apr 2008.
The definitive version is available at http://dx.doi.org/10.1002/jat.1285
Keywords and Phrases
Anti-oxidant enzymes; Cysteine; Ethanol; Free radicals; Glutathione; HepG2; Liver; Malondialdehyde; Oxidative stress; Radiation
Library of Congress Subject Headings
Free radicals (Chemistry)
International Standard Serial Number (ISSN)
Article - Journal
© 2008 John Wiley & Sons, All rights reserved.