Comparative genotoxicity of silver nanoparticles in human liver HepG2 and lung epithelial A549 cells

Abstract

With the rapid expanding of human exposure to silver nanoparticles (AgNPs), genotoxicity screening of nanosilver is necessary to ensure consumer safety. Here, we assessed one key DNA damage responsive pathway activated by GADD45a gene after 24 h of AgNPs exposure in stable luciferase reporter cell systems based on two widely used in vitro cell models, human liver HepG2 and lung epithelial A549 cells. The comet assay and micronucleus test were also conducted to confirm the genetic damage induced by AgNPs. Our results showed that AgNPs produced a strong dose-dependent increase in transcriptional activation of GADD45a promoter indicated by luciferase activity accompanying by the significant decreases in cell viability. Surprisingly, in HepG2-luciferase cells, the relative luciferase activity was greater than 4.5× the control level after being treated with 200 μg ml AgNPs. These results were generally in line with the positive and dose-dependent responses in cytotoxicity, DNA strand breaks indicated by Olive tail moment, tail DNA (%) and tail length, and chromosome damage indicated by induction of micronuclei, nucleoplasmic bridges, and nuclear buds. Additionally, compared with the A549-luciferase cells, the HepG2-luciferase cells seemed to be more susceptible to AgNPs as higher levels of genotoxicity were induced. We concluded that our GADD45a promoter-driven luciferase reporter gene cell system, together with the comet assay and micronucleus test, can be used as valuable tools for rapid screening of genotoxic potential of nanosilver. Copyright © 2016 John Wiley & Sons, Ltd.

Cytotoxicity and genotoxicity of nanosilver in stable GADD45α promoter‐driven luciferase reporter HepG2 and A549 cells

“…The AgNPs used in this study were characterized by TEM and a Malvern Zetasizer Nano S90 instrument as described previously . The primary particles of AgNPs analyzed by TEM were spherical and approximately 20–50 nm in diameter .…”

“…The mean hydrodynamic diameters for AgNPs ranged from 7.5 to 37.8 nm in deionized water and 11.7–50.8 nm in DMEM supplemented with 10% FBS . The zeta potential values for AgNPs in deionized water and DMEM supplemented with 10% FBS were −22.5 ± 1.82 and −10.8 ± 1.15, respectively …”

“…A detailed characteristic of AgNPs was published previously . The paritcle size of AgNPs was determined using the HITACHI H‐600 transmission electron microscope (Tokyo, Japan).…”

“…We measured the genotoxic damage in HepG2‐ and A549‐luciferase cells by comet assay and CBMN assay. The comet assay was performed under alkaline conditions using the methods described previously . Levels of DNA damage were recorded under the fluorescence microscope and images of 100 random selected cells were analyzed for each sample by Comet Assay Software Project (CASP, http://casplab.com/).…”

“…The parameter selected for the quantification of DNA damage was Olive tail moment. The micronuclei frequency was determined by CBMN assay as previously described with some minor modifications . The number of micronuclei was microscopically recorded in a total of 1000 binucleated cells for each sample according to the criteria described by Fenech .…”