title: SiO2 nanoparticles induce cytotoxicity and protein expression alteration in HaCaT cells.
abstract: BACKGROUND
  Nanometer silicon dioxide (nano-SiO2) has a wide variety of applications in material sciences, engineering and medicine; however, the potential cell biological and proteomic effects of nano-SiO2 exposure and the toxic mechanisms remain far from clear.
  
  
  RESULTS
  Here, we evaluated the effects of amorphous nano-SiO2 (15-nm, 30-nm SiO2). 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-SiO2 and micro-sized SiO2 particles. The IC50 value (50% concentration of inhibition) was associated with the size of SiO2 particles. Exposure to nano-SiO2 and micro-sized SiO2 particles also induced apoptosis in HaCaT cells in a dose-dependent manner. Furthermore, the smaller SiO2 particle size was, the higher apoptotic rate the cells underwent. The proteomic analysis revealed that 16 differentially expressed proteins were induced by SiO2 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-SiO2 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-SiO2 exposure.
authors.affiliation: Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Centre for Disease Control and Prevention, No, 21, Road 1st Tianbei, Luohu District, Shenzhen, 518020, PR China.
authors.forename: Xifei
authors.initials: X
authors.lastname: Yang
authors.forename: Jianjun
authors.initials: J
authors.lastname: Liu
authors.forename: Haowei
authors.initials: H
authors.lastname: He
authors.forename: Li
authors.initials: L
authors.lastname: Zhou
authors.forename: Chunmei
authors.initials: C
authors.lastname: Gong
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Wang
authors.forename: Lingqing
authors.initials: L
authors.lastname: Yang
authors.forename: Jianhui
authors.initials: J
authors.lastname: Yuan
authors.forename: Haiyan
authors.initials: H
authors.lastname: Huang
authors.forename: Lianhua
authors.initials: L
authors.lastname: He
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.forename: Zhixiong
authors.initials: Z
authors.lastname: Zhuang
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D053758:Nanoparticles / Q000633:toxicity*; D010316:Particle Size; D010449:Peptide Mapping; D011506:Proteins / Q000378:metabolism; D012822:Silicon Dioxide / Q000633:toxicity*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D011506:Proteins; D012822:Silicon Dioxide