Global Proteomics to Study Silica Nanoparticle-Induced Cytotoxicity and Its Mechanisms in HepG2 Cells

Silica nanoparticles (SiO(2) NPs) are commonly used in medical and pharmaceutical fields. Research into the cytotoxicity and overall proteomic changes occurring during initial exposure to SiO(2) NPs is limited. We investigated the mechanism of toxicity in human liver cells according to exposure time [0, 4, 10, and 16 h (h)] to SiO(2) NPs through proteomic analysis using mass spectrometry. SiO(2) NP-induced cytotoxicity through various pathways in HepG2 cells. Interestingly, when cells were exposed to SiO(2) NPs for 4 h, the morphology of the cells remained intact, while the expression of proteins involved in mRNA splicing, cell cycle, and mitochondrial function was significantly downregulated. These results show that the toxicity of the nanoparticles affects protein expression even if there is no change in cell morphology at the beginning of exposure to SiO(2) NPs. The levels of reactive oxygen species changed significantly after 10 h of exposure to SiO(2) NPs, and the expression of proteins associated with oxidative phosphorylation, as well as the immune system, was upregulated. Eventually, these changes in protein expression induced HepG2 cell death. This study provides insights into cytotoxicity evaluation at early stages of exposure to SiO(2) NPs through in vitro experiments.