Nanoparticle-driven DNA damage mimics irradiation-related carcinogenesis pathways.
The epidemiological association between cancer and exposure to ambient air pollution particles (particles with a 50% cut-off aerodynamic diameter of 10 microm (PM(10))) has been related to the ability of PM(10) and its constituent nanoparticles (NPs) to cause reactive oxidative species (ROS)-driven DNA damage. However, there are no data on the molecular response to these genotoxic effects. In order to assess whether PM(10), NP and ROS-driven DNA damage induce carcinogenesis pathways, A549 cells were treated with tert-butyl-hyperperoxide (Tbh), urban dust (UD), carbon black (CB), nanoparticulate CB (NPCB), benzo(a)pyrene (BaP) and NPCB coated with BaP for <or=24 h. Single- and double-strand breakage of DNA was determined by comet assay; cell cycle status was analysed using flow cytometry. Nuclear extracts or acid-extracted histones were used for Western blot analysis of p-ser15-p53 (p53 phosphorylated at ser15), p53 binding protein (53BP) 1, phospho-histone H2A.X (p-H2A.X) and phospho-BRCA1 (p-BRCA1). UD caused both single- and double-strand DNA breaks, while other tested NPs caused only single-strand DNA breaks. NPs significantly altered cell cycle kinetics. Tbh enhanced p-H2A.X after 1 and 6 h (2.1- and 2.2-fold, respectively). NP increased 53BP1 expression at 1 h (2.4-8.7-fold) and p-BRCA1 at 1-6 h. N-acetylcysteine blocked NP-driven p-ser15-p53 response. In conclusion, nanoparticles and reactive oxidative species induce DNA damage, activating p53 and proteins related to DNA repair, mimicking irradiation-related carcinogenesis pathways.
ELEGI/Colt Laboratories, University of Edinburgh, Edinburgh, Scotland, UK. robmroz@wp.pl
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Mroz
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Schins
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Li
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Jimenez
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Drost
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Holownia
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MacNee
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Donaldson
D000704:Analysis of Variance; D015153:Blotting, Western; D002274:Carcinogens, Environmental / Q000633:toxicity*; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced*; D020552:Comet Assay; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage / Q000528:radiation effects*; D019398:Genes, BRCA1; D006801:Humans; D066298:In Vitro Techniques; D015999:Multivariate Analysis; D009153:Mutagens / Q000633:toxicity; D053758:Nanoparticles / Q000633:toxicity*; D018384:Oxidative Stress; D010766:Phosphorylation; D017382:Reactive Oxygen Species / Q000378:metabolism; D012680:Sensitivity and Specificity
D002274:Carcinogens, Environmental; D009153:Mutagens; D017382:Reactive Oxygen Species