DNA damage and oxidative stress induced by CeO₂nanoparticles in human dermal fibroblasts: Evidence of a clastogenic effect as a mechanism of genotoxicity

Abstract

The broad range of applications of cerium oxide (CeO2) nanoparticles (nano-CeO2) has attracted industrial interest, resulting in greater exposures to humans and environmental systems in the coming years. Their health effects and potential biological impacts need to be determined for risk assessment. The aims of this study were to gain insights into the molecular mechanisms underlying the genotoxic effects of nano-CeO2 in relation with their physicochemical properties. Primary human dermal fibroblasts were exposed to environmentally relevant doses of nano-CeO2 (mean diameter, 7 nm; dose range, 6 × 10(-5)-6 × 10(-3) g/l corresponding to a concentration range of 0.22-22 µM) and DNA damages at the chromosome level were evaluated by genetic toxicology tests and compared to that induced in cells exposed to micro-CeO2 particles (mean diameter, 320 nm) under the same conditions. For this purpose, cytokinesis-blocked micronucleus assay in association with immunofluorescence staining of centromere protein A in micronuclei were used to distinguish between induction of structural or numerical chromosome changes (i.e. clastogenicity or aneuploidy). The results provide the first evidence of a genotoxic effect of nano-CeO2, (while not significant with micro-CeO2) by a clastogenic mechanism. The implication of oxidative mechanisms in this genotoxic effect was investigated by (i) assessing the impact of catalase, a hydrogen peroxide inhibitor, and (ii) by measuring lipid peroxidation and glutathione status and their reversal by application of N-acetylcysteine, a precusor of glutathione synthesis in cells. The data are consistent with the implication of free radical-related mechanisms in the nano-CeO2-induced clastogenic effect, that can be modulated by inhibition of cellular hydrogen peroxide release.

Sleep Deprivation-Induced Blood-Brain Barrier Breakdown and Brain Dysfunction are Exacerbated by Size-Related Exposure to Ag and Cu Nanoparticles. Neuroprotective Effects of a 5-HT3 Receptor Antagonist Ondansetron

“…Bar=35 μm increase in 5-HT greater than that often associated with the stress level in the circulation or in the brain [60][61][62]. Since NP intoxication induces severe oxidative stress alone, it is also quite likely that a combination of SD and NP intoxication exacerbates oxidative stress leading to endothelial cell membrane damage resulting in greater BBB leakage [63][64][65]. However, these NPs alone in normal animals did not induce BBB breakdown, although a slight abnormality in behavioral function was noted [48].…”

Treatment of Human Lens Epithelium with High Levels of Nanoceria Leads to Reactive Oxygen Species Mediated Apoptosis

“…It was reported that some nuclear uptake of EGCNPs take place at therapeutic concentrations (less 200 µg mL −1 ) [20]. This nuclear uptake is likely to have been increased at 400 µg mL −1 causing EGCNPs to aggregate inside the nuclei promoting genotoxicity [16]. Even though some nanoparticles have poor permeability into the nuclei, their entry is inevitable during mitosis where the nuclear membrane is broken as the cells prepare for division [46].…”

“…Additionally, many of the toxicological studies are performed on nanoceria with unknown or poor colloidal stability, a common problem for nanoceria, which gives rise to conflicting toxicological profiles. Although nanoceria are known for their powerful antioxidant properties, some studies have reported their ability to cause oxidative stress [13,15,16]. Ocular exposure is of particular interest due to the ease for sustained environmental exposure.…”

Cerium Oxide Nanoparticles in Lung Acutely Induce Oxidative Stress, Inflammation, and DNA Damage in Various Organs of Mice

“…It has been reported that oral administration of high dose (1000 mg/kg bw) of CeO 2 NPs induces significant DNA damage in peripheral blood leukocytes and liver cells, micronucleus formation in bone marrow and blood cells, and total cytogenetic changes in bone marrow [58]. Moreover, it has been shown that CeO 2 NPs induce oxidative stress and genotoxicity in human skin melanoma cells and human dermal fibroblasts [59, 60]. A more recent study has shown that low and more relevant concentration of CeO 2 NPs (0.01 mg/L) adversely affected in vitro fertilization in mice and caused DNA damage in mouse spermatozoa and oocytes [61].…”