Titanium dioxide nanoparticles trigger p53‐mediated damage response in peripheral blood lymphocytes

Abstract

Titanium dioxide nanoparticles (nano-TiO2) are widely used as a photocatalyst in air and water remediation. These nanoparticles are known to induce toxicity; however, their cytotoxic mechanism is not fully understood. In this study, we investigated the underlying mechanism of nano-TiO2-induced cytotoxicity in peripheral blood lymphocytes. We examined the genotoxic effects of nano-TiO2 in lymphocytes using alkaline single-cell gel electrophoresis (Comet) and cytokinesis-block micronucleus (CBMN) assays. Lymphocytes treated with nano-TiO2 showed significantly increased micronucleus formation and DNA breakage. Western-blot analysis to identify proteins involved in the p53-mediated response to DNA damage revealed the accumulation of p53 and activation of DNA damage checkpoint kinases in nano-TiO2-treated lymphocytes. However, p21 and bax, downstream targets of p53, were not affected, indicating that nano-TiO2 does not stimulate transactivational activity of p53. The generation of reactive oxygen species (ROS) in nano-TiO2-treated cells was also observed, andN-acetylcysteine (NAC) supplementation inhibited the level of nano-TiO2-induced DNA damage. Given that ROS-induced DNA damage leads to p53 activation in the DNA damage response, our results suggest that nano-TiO2 induces ROS generation in lymphocytes, thereby activating p53-mediated DNA damage checkpoint signals.

In vitro cytotoxicity and genotoxicity studies of titanium dioxide (TiO2) nanoparticles in Chinese hamster lung fibroblast cells

“…Recent studies have reported chromosomal damage induced by nano-TiO 2 in hamster embryo fibroblasts, blood lymphocytes, and in a human B-cell lymphoblastoid cell line using the micronucleus assay (Kang et al, 2008;Rahman et al, 2002;Wang et al, 2007), which was mostly associated with ROS-related DNA injury. Similarly, an in vivo study has shown the induction of DNA breakage in mice cells after exposure to P25-TiO 2 in drinking water (Trouiller et al, 2009).…”

Assessing nanoparticle toxicity in cell-based assays: influence of cell culture parameters and optimized models for bridging the in vitro–in vivo gap

“…The selection of a relevant cell type and source generally depends on the expected in vivo target organ and application of the NP 79 . In the vast majority of the studies the cells are exposed to the NP dispersion during a single incubation period ranging from 3 up to 48 hours 78,80,81 .…”

Role of Carnosine and Melatonin in Ameliorating Cardiotoxicity of Titanium Dioxide Nanoparticles in the Rats

“…Any reduction in mitochondrial membrane potential can lead to decreased energy production, which may results cytochrome c release and induce cellular apoptosis via calciumsensitive proteases, or through the activation of caspases and DNA fragmentation enzymes (Calcineurin et al 2001). Several studies in different cell lines showed that TiO 2 NP could cause genotoxicity represented by DNA damage and chromosomal aberrations (Rahman et al 2002;Kang et al 2008;Xu et al 2009;Petković et al 2011). The exposure of peripheral human lymphocytes to TiO 2 NPs can lead to the activation of DNA damage check points and accumulation of tumour suppressor protein p53 (Kang et al 2008).…”

“…It was found that red blood cells exposed to TiO 2 -NPs showed abnormal sedimentation, hemagglutination and hemolysis. Studies on animal models and in vitro experiments involving various cell lines have further proved the cytotoxicity of TiO 2 -NPs, including the inflammation of many organs according to their rout of entry, induction of chromatin condensation, nuclear fragmentation, caspase activation, and even apoptosis (Kang et al 2008;Zhu et al 2012). The cytotoxicity of TiO 2-NPs depend on their physical and chemical properties, especialy their size, as the smaller the particles, the more damage they cause (Sohaebuddin et al 2010).…”

“…The exposure to nanoparticle can be either accidentally due to occupational exposure, or intentionally through different routs such as nose by inhalation, mouth by ingestion, skin contact or intravenous injection (Zhu et al 2012;Khan and Maskat 2014). Owing to their tiny size, NPs can get an access to many biological structures, interacting with molecules such as proteins, lipids and nucleic acids, which may, in turn, interfere with their normal function, damage the subcellular organelles and cause cell death (Buzea et al 2007;Kang et al 2008;Park et al 2008;Zhao and Castranova 2011;Zhu et al 2012;Tay 2014). There are evidences showing that TiO2 -NPs may induce the cardiotoxicity (Jawad et al 2011) as well as toxicity of the circulatory system.…”