title: Zinc oxide nanoparticles induce oxidative DNA damage and ROS-triggered mitochondria mediated apoptosis in human liver cells (HepG2).
abstract: The wide scale use of Zinc oxide (ZnO) nanoparticles in the world consumer market makes human beings more prone to the exposure to ZnO nanoparticles and its adverse effects. The liver, which is the primary organ of metabolism, might act as a major target organ for ZnO nanoparticles after they gain entry into the body through any of the possible routes. Therefore, the aim of the present study was to assess the apoptotic and genotoxic potential of ZnO nanoparticles in human liver cells (HepG2) and the underlying molecular mechanism of its cellular toxicity. The role of dissolution in the toxicity of ZnO nanoparticles was also investigated. Our results demonstrate that HepG2 cells exposed to 14-20 μg/ml ZnO nanoparticles for 12 h showed a decrease in cell viability and the mode of cell death induced by ZnO nanoparticles was apoptosis. They also induced DNA damage which was mediated by oxidative stress as evidenced by an increase in Fpg sensitive sites. Reactive oxygen species triggered a decrease in mitochondria membrane potential and an increase in the ratio of Bax/Bcl2 leading to mitochondria mediated pathway involved in apoptosis. In addition, ZnO nanoparticles activated JNK, p38 and induced p53(Ser15) phosphorylation. However, apoptosis was found to be independent of JNK and p38 pathways. This study investigating the effects of ZnO nanoparticles in human liver cells has provided valuable insights into the mechanism of toxicity induced by ZnO nanoparticles.
authors.affiliation: Nanomaterial Toxicology Group, CSIR-Indian Institute of Toxicology Research, Mahatma Gandhi Marg, P.O. Box 80, Lucknow, 226001, Uttar Pradesh, India.
authors.forename: Vyom
authors.initials: V
authors.lastname: Sharma
authors.forename: Diana
authors.initials: D
authors.lastname: Anderson
authors.forename: Alok
authors.initials: A
authors.lastname: Dhawan
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D004249:DNA Damage; D004791:Enzyme Inhibitors / Q000494:pharmacology; D056945:Hep G2 Cells; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D015227:Lipid Peroxidation; D053078:Membrane Potential, Mitochondrial; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009153:Mutagens / Q000633:toxicity*; D053758:Nanoparticles / Q000633:toxicity* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010316:Particle Size; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015034:Zinc Oxide / Q000378:metabolism / Q000494:pharmacology* / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D051017:Apoptosis Regulatory Proteins; D004791:Enzyme Inhibitors; D009153:Mutagens; D017382:Reactive Oxygen Species; D007770:L-Lactate Dehydrogenase; D020928:Mitogen-Activated Protein Kinases; D015034:Zinc Oxide