DNA damage and alterations in expression of DNA damage responsive genes induced by TiO2 nanoparticles in human hepatoma HepG2 cells

Department of Genetic Toxicology and Cancer Biology, National Institute of Biology , Ljubljana , Slovenia.
Nanotoxicology (Impact Factor: 6.41). 11/2010; 5(3):341-53. DOI: 10.3109/17435390.2010.507316
Source: PubMed


We investigated the genotoxic responses to two types of TiO2 nanoparticles (<25 nm anatase: TiO(2)-An, and <100 nm rutile: TiO2-Ru) in human hepatoma HepG2 cells. Under the applied exposure conditions the particles were agglomerated or aggregated with the size of agglomerates and aggregates in the micrometer range, and were not cytotoxic. TiO2-An, but not TiO2-Ru, caused a persistent increase in DNA strand breaks (comet assay) and oxidized purines (Fpg-comet). TiO2-An was a stronger inducer of intracellular reactive oxygen species (ROS) than TiO2-Ru. Both types of TiO2 nanoparticles transiently upregulated mRNA expression of p53 and its downstream regulated DNA damage responsive genes (mdm2, gadd45α, p21), providing additional evidence that TiO2 nanoparticles are genotoxic. The observed differences in responses of HepG2 cells to exposure to anatase and rutile TiO2 nanoparticles support the evidence that the toxic potential of TiO2 nanoparticles varies not only with particle size but also with crystalline structure.

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    • "Concentration-dependent alterations in cell cycle progression have been observed in keratinocytes treated with TiO 2 -NPs (Huang et al., 2009; Kocbek et al., 2010). Also, TiO 2 NPs significantly alter the immune response, lipid and fatty acid metabolism, apoptosis in hepatocytes, and the activation of redox-sensitive signaling pathways (Petkovic et al., 2010; Singh et al., 2007; Thurn et al., 2007), all of which would implicate TiO 2 NPs in systemic health risks (Ferin and Leach, 1973; Horie et al., 2012; Kim et al., 2010; Lee et al., 1986; Singh et al., 2007). Many studies have highlighted that oxidative stress caused by metal oxides modulate several signaling pathways. "
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    ABSTRACT: Abstract Food grade TiO2 (E171) is a synthetic additive, and widely used as a coloring agent in many foods, pharmaceutical and personal care products. A few reports have highlighted that insoluble particulates (less than 200 nm) of food grade TiO2 are found in many foods and confectionary products. However, information regarding the physico-chemical properties (i.e., size and shape)-based food grade TiO2 nanotoxicity related human health issues are limited. The main goal of this study is to examine the presence of nano-sized particulates and its structural characteristics of food grade- TiO2 materials and to assess the acute cellular uptake and metabolic stress induced by these particulates in human lung fibroblast (WI-38) cells. The results of transmission electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction studies indicated that about food grade TiO2 sample contains spherical shaped particulate forms in the nano-scale range, <100 nm. The intracellular oxidative stress in human lung fibroblast cells (WI-38) was assessed through studies investigating the cellular uptake of the particles, changes in nuclear and cytoplasmic morphology, intracellular ROS, mitochondrial trans-membrane potential, the cell cycle and the expression of genes linked to metabolic stress markers. Altogether our data clearly indicate that primary metabolic stress indicators such as changes in the intracellular ROS, the dose-dependent loss of the mitochondrial membrane potential, alterations in cell cycle progression (G2/M > S > G0/G1) and changes in the TNF and CYP1A gene expression pattern are linked to cellular stress. Thus, food grade TiO2 as nano-scaled contaminants could not only be potential human health risk factors, suggesting that safety considerations with special respect to a few crucial factors such as size, and shape should be considered and regulated by food regulators.
    Environmental Toxicology and Pharmacology 01/2015; 39(1):176-186. DOI:10.1016/j.etap.2014.11.021 · 2.08 Impact Factor
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    • "Moreover, other in vitro studies have demonstrated that titanium dioxide (TiO 2 ) NMs can induce p53 expression by oxidative DNA damage. This p53 induction was associated with cell cycle arrest and apoptosis (Kang et al. 2008; Petkovic et al. 2011; Wu et al. 2010). The involvement of p53 was also implicated in the induction of apoptosis and carcinogenesis following the exposure of cNTs in rodent models (intraperitoneal injection and intratracheal instillation ) (Park et al. 2011; Poland et al. 2008; Takagi et al. 2008). "
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    ABSTRACT: Manufactured nanomaterials (MNMs) have the potential to improve everyday life as they can be utilised in numerous medical applications and day-to-day consumer products. However, this increased use has led to concerns about the potential environmental and human health impacts. The protein p53 is a key transcription factor implicated in cellular defence and reparative responses to various stress factors. Additionally, p53 has been implicated in cellular responses following exposure to some MNMs. Here, the role of the MNM mediated p53 induction and activation and its downstream effects following exposure to five well-characterised materials [namely two types of TiO2, two carbon black (CB), and one single-walled carbon nanotube (SWCNT)] were investigated. MNM internalisation, cellular viability, p53 protein induction and activation, oxidative stress, inflammation and apoptosis were measured in murine cell line and primary pulmonary macrophage models. It was observed that p53 was implicated in the biological responses to MNMs, with oxidative stress associated with p53 activation (only following exposure to the SWCNT). We demonstrate that p53 acted as an antioxidant and anti-inflammatory in macrophage responses to SWCNT and CB NMs. However, p53 was neither involved in MNM-induced cellular toxicity, nor in the apoptosis induced by these MNMs. Moreover, the physicochemical characteristics of MNMs seemed to influence their biological effects-SWCNT the materials with the largest surface area and a fibrous shape were the most cytotoxic in this study and were capable of the induction and activation of p53.
    Archive für Toxikologie 08/2014; 89(9). DOI:10.1007/s00204-014-1324-5 · 5.98 Impact Factor
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    • "Upon exposure, these released TiO 2 nanoparticles may interact with the human organism through inhalation or dermal contacts and get deposited inside the body. Various toxicological studies have demonstrated toxic effects of some types of TiO 2 nanoparticles in this case [13] [14] [15]. Few studies have examined the concentration, morphology and chemical composition of the generated aerosol wear particles [16] [17] [18]. "
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    ABSTRACT: A study highlighting the aspect of the generation of aerosol wear particles during abrasion is presented. The substrate chosen is a masonry brick which is reinforced with TiO2 nanoparticles. This is done using a pin on plate arrangement. The material removal mechanism via fracturing is first understood. The parameter chosen for the study is the normal load. The formed aerosols are then characterized by their number concentration, particle size distribution, individual particle shape, size and chemical composition. Having irregular shapes, the aerosol wear particles have unimodal size distributions with 5–7 % (in mass) of Ti content. The size mode increases with the increase in normal load. However, at higher normal loads, while there is an unexpected increase in the wear mass, the maximum concentration of the aerosol particles saturates. During the whole study, no free nanoparticles of TiO2 were found.
    Tribology Letters 08/2014; 55(2):227-234. DOI:10.1007/s11249-014-0351-y · 1.74 Impact Factor
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