DNA microarray analyses for HepG2 cells exposed to silver nanoparticles

From the result of the gene expression analyses of human hepatoma cell line, HepG2, a number of genes associated with cell proliferation and DNA repair were distinctively up-regulated by Ag-nanoparticle exposure, suggesting that Ag-nanoparticles might stimulate cell proliferation and DNA damage, which are considered to be mechanisms playing an important role for carcinogenesis and tumor progression. The inductions of these genes involved in cell proliferation were also observed in PS-nanoparticles and Ag2CO3-exposed cells. In addition, the inductions of DNA repair-associated genes were also observed in Ag2CO3-exposure. These results suggest that both “nanoshape” and “silver” can cause the inductions of these gene expression patterns. Furthermore, cysteine, a strong ionic silver ligand partially abolished these gene expressions induced by silver nanoparticles. Ionic silver sourced from Ag-nanoparticles could not fully explain these gene expressions. In this study, we examined the gene expression alteration in human hepatoma cell line, HepG2 following exposures of silver nanoparticles (7-10 nm), polysthylene nanoparticles (15 nm) and silver carbonate using DNA microarray with 8795 human genes. Furthermore, we also performed the DNA microarray analyses for the cells exposed to silver nanoparticle in the presence of 5mM N-acetyl-L-cysteine to examine the contribution of silver ion to silver nanoparticle exposure.