Department of Toxicology, Dalian Medical University, Liaoning, China.
Chem Biol Interact. 2011 Feb 1;189(3):186-91. doi: 10.1016/j.cbi.2010.12.011. Epub 2010 Dec 21.
Potassium bromate (KBrO(3), PB) is a by-product of ozone used as disinfectant in drinking water. And PB is also a widely used food additive. However, there is little known about its adverse effects, in particular those related to its genotoxicity in humans. The aim of this study was to investigate the genotoxic effects of PB and the underlying mechanisms, using human hepatoma cell line, HepG2. Exposure of the cells to PB caused a significant increase of DNA migration in single cell gel electrophoresis (SCGE) assay and micronuclei (MN) frequencies in micronucleus test (MNT) at all tested concentrations (1.56-12.5 mM and 0.12-1 mM), which suggested that PB-mediated DNA strand breaks and chromosome damage. To indicate the role of antioxidant in those effects, DNA migration was monitored by pre-treatment with hydroxytyrosol (HT) as an antioxidant in SCGE assay. It was found that DNA migration with pre-treatment of HT was dramatically decreased. To elucidate the genotoxicity mechanisms, the study monitored the levels of reactive oxygen species (ROS), glutathione (GSH) and 8-hydroxydeoxyguanosine (8-OHdG). PB was shown to induce ROS production (12.5 mM), GSH depletion (1.56-12.5 mM) and 8-OHdG formation (6.25-12.5 mM) in HepG2 cells. Moreover, lysosomal membrane stability and mitochondrial membrane potential were further studied for the mechanisms of PB-induced genotoxicity. A significant increase was found in the range of 6.25-12.5 mM in lysosomal membrane stability assay. However, under these PB concentrations, we were not able to detect the changes of mitochondrial membrane potential. These results suggest that PB exerts oxidative stress and genotoxic effects in HepG2 cells, possibly through the mechanisms of lysosomal damage, an earlier event preceding the oxidative DNA damage.
溴酸钾（KBrO(3)，PB）是臭氧作为饮用水消毒剂的副产物。PB 也是一种广泛使用的食品添加剂。然而，人们对其不良影响知之甚少，特别是其在人类中的遗传毒性。本研究旨在使用人肝癌细胞系 HepG2 研究 PB 的遗传毒性作用及其潜在机制。细胞暴露于 PB 会导致单细胞凝胶电泳（SCGE）试验中 DNA 迁移的显著增加和微核试验（MNT）中微核（MN）频率的增加，在所有测试浓度（1.56-12.5 mM 和 0.12-1 mM）下，这表明 PB 介导的 DNA 链断裂和染色体损伤。为了表明抗氧化剂在这些作用中的作用，通过用羟基酪醇（HT）预处理来监测 SCGE 试验中的 DNA 迁移。结果发现，用 HT 预处理后的 DNA 迁移明显减少。为了阐明遗传毒性机制，本研究监测了活性氧（ROS）、谷胱甘肽（GSH）和 8-羟基脱氧鸟苷（8-OHdG）的水平。结果表明，PB 诱导 ROS 产生（12.5 mM）、GSH 耗竭（1.56-12.5 mM）和 8-OHdG 形成（6.25-12.5 mM）在 HepG2 细胞中。此外，还进一步研究了溶酶体膜稳定性和线粒体膜电位，以了解 PB 诱导遗传毒性的机制。在溶酶体膜稳定性试验中，在 6.25-12.5 mM 的范围内发现显著增加。然而，在这些 PB 浓度下，我们无法检测到线粒体膜电位的变化。这些结果表明，PB 对 HepG2 细胞产生氧化应激和遗传毒性作用，可能通过溶酶体损伤的机制，这是氧化 DNA 损伤之前的一个早期事件。
