title: Repair activity of oxidatively damaged DNA and telomere length in human lung epithelial cells after exposure to multi-walled carbon nanotubes.
abstract: One type of carbon nanotubes (CNTs) (MWCNT-7, from Mitsui) has been classified as probably carcinogenic to humans, however insufficient data does not warrant the same classification for other types of CNTs. Experimental data indicate that CNT exposure can result in oxidative stress and DNA damage in cultured cells, whereas these materials appear to induce low or no mutagenicity. Therefore, the present study aimed to investigate whether in vitro exposure of cultured airway epithelial cells (A549) to multi-walled CNTs (MWCNTs) could increase the DNA repair activity of oxidatively damaged DNA and drive the cells toward replicative senescence, assessed by attrition of telomeres. To investigate this, H2O2and KBrO3were used to induce DNA damage in the cells and the effect of pre-exposure to MWCNT tested for a change in repair activity inside the cells or in the extract of treated cells. The effect of MWCNT exposure on telomere length was investigated for concentration and time response. We report a significantly increased repair activity in A549 cells exposed to MWCNTs compared to non-exposed cells, suggesting that DNA repair activity may be influenced by exposure to MWCNTs. The telomere length was decreased at times longer than 24h, but this decrease was not concentration dependent. The results suggest that the seemingly low mutagenicity of CNTs in cultured cells may be associated with an increased DNA repair activity and a replicative senescence, which may counteract the manifestation of DNA lesions to mutations.
authors.affiliation: Genetics Unit, CNR Institute of Clinical Physiology, Via G. Moruzzi 1, 56124 Pisa, Pisa, Italy.|Department of Public Health, Section of Environmental Health, University of Copenhagen, Øster Farimagsgade 5A, DK-1014 Copenhagen, Denmark.
authors.forename: Andrea
authors.initials: A
authors.lastname: Borghini
authors.affiliation: Department of Public Health, Section of Environmental Health, University of Copenhagen, Øster Farimagsgade 5A, DK-1014 Copenhagen, Denmark mwro@sund.ku.dk.
authors.forename: Martin
authors.initials: M
authors.lastname: Roursgaard
authors.affiliation: Genetics Unit, CNR Institute of Clinical Physiology, Via G. Moruzzi 1, 56124 Pisa, Pisa, Italy.
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Andreassi
authors.affiliation: Department of Public Health, Section of Environmental Health, University of Copenhagen, Øster Farimagsgade 5A, DK-1014 Copenhagen, Denmark.
authors.forename: Ali
authors.initials: A
authors.lastname: Kermanizadeh
authors.affiliation: Department of Public Health, Section of Environmental Health, University of Copenhagen, Øster Farimagsgade 5A, DK-1014 Copenhagen, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Møller
mesh_terms: D000072283:A549 Cells; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects*; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008168:Lung; D037742:Nanotubes, Carbon / Q000633:toxicity*; D018384:Oxidative Stress; D016615:Telomere / Q000187:drug effects*
chemical_list: D037742:Nanotubes, Carbon; D004247:DNA