Cerium oxide nanoparticles induce cytotoxicity in human hepatoma SMMC-7721 cells via oxidative stress and the activation of MAPK signaling pathways

Lanthanide cerium oxide (CeO2) nanoparticles have extensive applications in industrial fields, and concerns regarding their potential toxicity in humans and their environmental impact have increased. We investigated the underlying molecular mechanisms by which CeO2 nanoparticles induce toxicity in human hepatoma SMMC-7721 cells.Our results demonstrated that CeO2 nanoparticles reduced viability, caused dramatic morphological damage, and induced apoptosis in SMMC-7721 cells. CeO2 nanoparticles significantly increased the production of reactive oxygen species (ROS) and malondialdehyde (MDA), and significantly reduced the activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-px) and catalase (CAT). The phosphorylation levels of ERK1/2, JNK and p38 MAPK were significantly elevated after treatment with CeO2 nanoparticles. Pretreatment with the antioxidant N-acetyl-cysteine (NAC): reduced the induction of ROS and MDA by CeO2 nanoparticles; recovered the activity of SOD, GSH-px and CAT; reduced the phosphorylation levels of ERK1/2, JNK and p38; and attenuated CeO2 nanoparticles-induced damage and apoptosis in SMMC-7721 cells.Our data demonstrated that CeO2 nanoparticles induced damage and apoptosis in human SMMC-7721 cells via oxidative stress and the activation of MAPK signaling pathways.