title: Multi-platform genotoxicity analysis of silver nanoparticles in the model cell line CHO-K1.
abstract: Investigation of the genotoxic potential of nanomaterials is essential to evaluate if they pose a cancer risk for exposed workers and consumers. The Chinese hamster ovary cell line CHO-K1 is recommended by the OECD for use in the micronucleus assay and is commonly used for genotoxicity testing. However, studies investigating if this cell line is suitable for the genotoxic evaluation of nanomaterials, including induction of DNA adduct and micronuclei formation, are rare and for silver nanoparticles (Ag NPs) missing. Therefore, we here systematically investigated DNA and chromosomal damage induced by BSA coated Ag NPs (15.9±7.6 nm) in CHO-K1 cells in relation to cellular uptake and intracellular localization, their effects on mitochondrial activity and production of reactive oxygen species (ROS), cell cycle, apoptosis and necrosis. Ag NPs are taken up by CHO-K1 cells and are presumably translocated into endosomes/lysosomes. Our cytotoxicity studies demonstrated a concentration-dependent decrease of mitochondrial activity and increase of intracellular reactive oxygen species (ROS) in CHO-K1 cells following exposure to Ag NPs and Ag⁺ (0-20 μg/ml) for 24h. Annexin V/propidium iodide assay showed that Ag NPs and Ag⁺ induced apoptosis and necrosis, which is in agreement with an increased fraction of cells in subG1 phase of the cell cycle. Genotoxicity studies showed that Ag NPs but also silver ions (Ag⁺) induced bulky-DNA adducts, 8-oxodG and micronuclei formation in a concentration-dependent manner, however, there were quantitative and qualitative differences between the particulate and ionic form of silver. Taken together, our multi-platform genotoxicity and cytotoxicity analysis demonstrates that CHO-K1 cells are suitable for the investigation of genotoxicity of nanoparticles like Ag NPs.
authors.affiliation: National Center for Nanoscience and Technology, Chinese Academy of Science, No. 11, Beiyitiao Zhongguancun, Beijing 100190, China.
authors.forename: Xiumei
authors.initials: X
authors.lastname: Jiang
authors.forename: Rasmus
authors.initials: R
authors.lastname: Foldbjerg
authors.forename: Teodora
authors.initials: T
authors.lastname: Miclaus
authors.forename: Liming
authors.initials: L
authors.lastname: Wang
authors.forename: Rajinder
authors.initials: R
authors.lastname: Singh
authors.forename: Yuya
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Duncan
authors.initials: D
authors.lastname: Sutherland
authors.forename: Chunying
authors.initials: C
authors.lastname: Chen
authors.forename: Herman
authors.initials: H
authors.lastname: Autrup
authors.forename: Christiane
authors.initials: C
authors.lastname: Beer
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D016466:CHO Cells; D002453:Cell Cycle / Q000187:drug effects; D004396:Coloring Agents; D006224:Cricetinae; D003412:Cricetulus; D018736:DNA Adducts; D003849:Deoxyguanosine / Q000031:analogs & derivatives; D005434:Flow Cytometry; D013058:Mass Spectrometry; D015162:Micronucleus Tests; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D009152:Mutagenicity Tests / Q000379:methods*; D009153:Mutagens; D053758:Nanoparticles / Q000008:administration & dosage / Q000633:toxicity*; D009336:Necrosis; D017382:Reactive Oxygen Species / Q000378:metabolism; D012834:Silver / Q000008:administration & dosage / Q000633:toxicity*; D013778:Tetrazolium Salts; D013844:Thiazoles
chemical_list: D004396:Coloring Agents; D018736:DNA Adducts; D009153:Mutagens; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013844:Thiazoles; D012834:Silver; D000080242:8-Hydroxy-2'-Deoxyguanosine; C022616:thiazolyl blue; D003849:Deoxyguanosine
keywords: 8-oxodG; Cytotoxicity; DNA adduct; Genotoxicity; Micronucleus assay; Silver nanoparticle