title: Zinc oxide nanoparticles induce lipoxygenase-mediated apoptosis and necrosis in human neuroblastoma SH-SY5Y cells.
abstract: Zinc oxide nanoparticles (ZnO NPs) are known to induce oxidative stress and modulate an inflammatory process in various cell types. Although the cytotoxic effects of ZnO NPs in various cell types have been evaluated, few neurotoxic surveys on ZnO NPs as well as rescue studies have been reported. This study was designed to examine the neurotoxic ZnO NP concentration according to exposure time and dose, and the mechanisms that underlie ZnO NP-induced neurotoxicity in the SH-SY5Y human neuroblastoma cell line. A significant reduction in neuronal viability as well as distinct morphological findings resulted from application of 15 μM ZnO NPs. Apoptotic injury-as measured by annexin V and caspase 3/7 activities-was significantly elevated at 12 h and 24 h, but not 6 h, after ZnO NP exposure. However, electron microscopy revealed typical necrotic characteristics, such as swelling or loss of cell organelles and rupture of the cytosolic or nuclear membrane at 12 h and 24 h after ZnO NP exposure. In rescue studies, the lipoxygenase (LOX) inhibitor esculetin attenuated ZnO NP-induced neuronal injury. The elevation of PI3 kinase (PI3K) and p-Akt/Akt activities induced by ZnO NP was significantly decreased by esculetin or LY294002. Allopurinol, N-acetyl-l-cysteine and α-tocopherol protected ZnO NP-induced cytotoxicity. Sodium nitroprusside (SNP)-induced neurotoxicity and ZnO NP-mediated NO overproduction were ameliorated by esculetin. Esculetin reduced the production of reactive oxygen species (ROS) and the depletion of antioxidant enzymes induced by ZnO NPs. The concentration of zinc from the dissolution of ZnO NPs increased in proportion to increases in the ZnO NPs concentration. These results suggest that ZnO NPs induce apoptosis via the PI3K/Akt/caspase-3/7 pathway and necrosis by LOX-mediated ROS production elevation.
authors.affiliation: College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University, Chuncheon 200-701, South Korea.
authors.forename: Jun-Hyung
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Bio-Imaging Center, Korea Basic Science Institute, Chuncheon 200-701, South Korea.
authors.forename: Myeong Seon
authors.initials: MS
authors.lastname: Jeong
authors.affiliation: College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University, Chuncheon 200-701, South Korea.
authors.forename: Dong-Yung
authors.initials: DY
authors.lastname: Kim
authors.affiliation: Bio-Imaging Center, Korea Basic Science Institute, Chuncheon 200-701, South Korea.
authors.forename: Song
authors.initials: S
authors.lastname: Her
authors.affiliation: College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University, Chuncheon 200-701, South Korea. Electronic address: mbwie@kangwon.ac.kr.
authors.forename: Myung-Bok
authors.initials: MB
authors.lastname: Wie
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D008084:Lipoxygenase / Q000378:metabolism*; D053758:Nanoparticles / Q000008:administration & dosage*; D009336:Necrosis / Q000139:chemically induced; D018384:Oxidative Stress / Q000187:drug effects*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015034:Zinc Oxide / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D008084:Lipoxygenase; D019869:Phosphatidylinositol 3-Kinases; D015034:Zinc Oxide
keywords: Apoptosis; Esculetin; Necrosis; PI3K/Akt; Zinc oxide nanoparticles