SiO2nanoparticles induce cytotoxicity and protein expression alteration in HaCaT cells

Nanometer silicon dioxide (nano-SiO 2 ) has a wide variety of applications in material sciences, engineering and medicine; however, the potential cell biological and proteomic effects of nano-SiO 2 exposure and the toxic mechanisms remain far from clear. Results Here, we evaluated the effects of amorphous nano-SiO 2 (15-nm, 30-nm SiO 2 ). on cellular viability, cell cycle, apoptosis and protein expression in HaCaT cells by using biochemical and morphological analysis, two-dimensional differential gel electrophoresis (2D-DIGE) as well as mass spectrometry (MS). We found that the cellular viability of HaCaT cells was significantly decreased in a dose-dependent manner after the treatment of nano-SiO 2 and micro-sized SiO 2 particles. The IC 50 value (50% concentration of inhibition) was associated with the size of SiO 2 particles. Exposure to nano-SiO 2 and micro-sized SiO 2 particles also induced apoptosis in HaCaT cells in a dose-dependent manner. Furthermore, the smaller SiO 2 particle size was, the higher apoptotic rate the cells underwent. The proteomic analysis revealed that 16 differentially expressed proteins were induced by SiO 2 exposure, and that the expression levels of the differentially expressed proteins were associated with the particle size. The 16 proteins were identified by MALDI-TOF-TOF-MS analysis and could be classified into 5 categories according to their functions. They include oxidative stress-associated proteins; cytoskeleton-associated proteins; molecular chaperones; energy metabolism-associated proteins; apoptosis and tumor-associated proteins. Conclusions These results showed that nano-SiO 2 exposure exerted toxic effects and altered protein expression in HaCaT cells. The data indicated the alterations of the proteins, such as the proteins associated with oxidative stress and apoptosis, could be involved in the toxic mechanisms of nano-SiO 2 exposure.