title: [Roles of DNA dependent protein kinase in silica-induced cyclin E and CDK2 expressions and cell cycle changes in human embryo lung fibroblasts].
abstract: OBJECTIVE
  To study the roles of DNA dependent protein kinase (DNA-PK)in silica-induced cell cycle changes and expressions of CyclinE and CDK2 in human embryo lung fibroblasts (HELF).
  
  
  METHODS
  The expressions of Ku80 and DNA-PKcs proteins were inhibited by siRNA plasmids, respectively. Flow cytometry was used to detect the distributions of cell cycle and western blot assay was used to determine the expression levels of CyclinE and CDK2 after cells were exposed to 200 microg/ml silica for 0, 3, 6, 12, 24 h.
  
  
  RESULTS
  The proportion of G1 phases in negative control cells decreased from 83.53% +/- 2.24% to 69.11% +/- 3.12% after exposure to silica; the proportion of G1 phases in H-Ku80 and H-PKcs cells exposed to silica decreased from 85.16% +/- 3.73% to 59.92% +/- 3.31% and from 75.06% +/- 2.23% to 58.32% +/- 1.35%, respectively (P < 0.05). The exposure to silica resulted in the increasing protein expression levels of CyclinE and CDK2 in negative control cells, and the expression levels of CyclinE were obviously suppressed in H-Ku80 and H-PKcs as compared with control cells. However, the expression level of CDK2 protein did not change significantly.
  
  
  CONCLUSIONS
  DNA-PK might play a role in silica-induced alternations of cell cycle and regulate silica-induced overexpression of CyclinE in human embryo lung fibroblasts.
authors.affiliation: National Institute of Occupation Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
authors.forename: Hai-Feng
authors.initials: HF
authors.lastname: Liu
authors.forename: Feng-Mei
authors.initials: FM
authors.lastname: Zhang
authors.forename: Bing-Ci
authors.initials: BC
authors.lastname: Liu
authors.forename: Xiao-Wei
authors.initials: XW
authors.lastname: Jia
authors.forename: Meng
authors.initials: M
authors.lastname: Ye
mesh_terms: D002453:Cell Cycle / Q000187:drug effects*; D002478:Cells, Cultured; D019927:Cyclin E / Q000378:metabolism*; D051357:Cyclin-Dependent Kinase 2 / Q000378:metabolism*; D051747:DNA-Activated Protein Kinase / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000166:cytology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D015513:Oncogene Proteins / Q000378:metabolism*; D012822:Silicon Dioxide / Q000494:pharmacology
chemical_list: C475820:CCNE1 protein, human; D019927:Cyclin E; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D012822:Silicon Dioxide; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2