title: Cyto-genotoxic and DNA methylation changes induced by different crystal phases of TiO2-np in bronchial epithelial (16-HBE) cells.
abstract: With the increase in use of TiO2-np, a better understanding of their safety is important. In the present study the effect of different crystal phases of TiO2-np (anatase, rutile and anatase: rutile mixture; 20-26nm) were studied for cyto-genotoxicity and global DNA methylation and hydroxymethylation. Cytotoxic response was observed at a concentration of 25μg/ml for the particles tested. Results of comet and micronucleus (with and without CytB) assays revealed significant genotoxic effect of these particles. Flow cytometry revealed cell cycle arrest in the S-phase. Based on the results, toxicity of the particles could be correlated with their physico-chemical properties (i.e. smaller size and hydrodynamic diameter and larger surface area), anatase form being the most toxic. From the results of the cyto-genotoxicity assays, concentrations were determined for the epigenetic study. Effect on global DNA methylation and hydroxymethylation levels were studied at cyto-genotoxic (25μg/ml), genotoxic (12.5μg/ml) and sub cyto-genotoxic (3.25μg/ml) concentrations using LC-MS/MS analysis. Though no significant changes were observed for 3h treatment schedule; significant hypomethylation were observed at 24h for anatase (significant at 3.25 and 25μg/ml), rutile (significant at 3.25 and 25μg/ml) and anatase: rutile mixture (significant at 25μg/ml) forms. The results suggest that epigenetic changes could occur at sub cyto-genotoxic concentrations. And hence for complete characterization of nanoparticle toxicity, epigenetic studies should be performed along with conventional toxicity testing methods.
authors.affiliation: K.U.Leuven, Department of Public Health and Primary Care, Centre Environment & Health, B-3000 Leuven, Belgium. Electronic address: gmanosij@gmail.com.
authors.forename: Manosij
authors.initials: M
authors.lastname: Ghosh
authors.affiliation: K.U.Leuven, Department of Public Health and Primary Care, Centre Environment & Health, B-3000 Leuven, Belgium.
authors.forename: Deniz
authors.initials: D
authors.lastname: Öner
authors.affiliation: K.U.Leuven, Department of Public Health and Primary Care, Centre Environment & Health, B-3000 Leuven, Belgium.
authors.forename: Radu-Corneliu
authors.initials: RC
authors.lastname: Duca
authors.affiliation: Department of Oral Health Sciences, KU Leuven BIOMAT, 3000 Leuven, Belgium.
authors.forename: Stevan M
authors.initials: SM
authors.lastname: Cokic
authors.affiliation: K.U.Leuven, Department of Immunology and Microbiology, Leuven, Belgium.
authors.forename: Sven
authors.initials: S
authors.lastname: Seys
authors.affiliation: Centre for Surface Chemistry and Catalysis, KU Leuven, Celestijnenlaan 200f, Heverlee, Leuven, Belgium.
authors.forename: Stef
authors.initials: S
authors.lastname: Kerkhofs
authors.affiliation: Department of Oral Health Sciences, KU Leuven BIOMAT, 3000 Leuven, Belgium.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Van Landuyt
authors.affiliation: K.U.Leuven, Department of Public Health and Primary Care, Centre Environment & Health, B-3000 Leuven, Belgium.
authors.forename: Peter
authors.initials: P
authors.lastname: Hoet
authors.affiliation: K.U.Leuven, Department of Public Health and Primary Care, Centre Environment & Health, B-3000 Leuven, Belgium; Idewe, External Service for Prevention and Protection at Work, B-3001, Heverlee, Belgium. Electronic address: lode.godderis@med.kuleuven.be.
authors.forename: Lode
authors.initials: L
authors.lastname: Godderis
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001980:Bronchi / Q000187:drug effects* / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004249:DNA Damage / Q000187:drug effects*; D019175:DNA Methylation / Q000187:drug effects*; D004847:Epithelial Cells / Q000187:drug effects* / Q000473:pathology; D005434:Flow Cytometry; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D053768:Metal Nanoparticles / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry / Q000633:toxicity*; D018675:Toxicity Tests / Q000379:methods; D014407:Tumor Cells, Cultured
chemical_list: C009495:titanium dioxide; D014025:Titanium
keywords: DNA methylation; Epigenetics; Genotoxic; Titanium dioxide