title: Radiation induces phosphorylation of STAT3 in a dose- and time-dependent manner.
abstract: BACKGROUND
  We have reported the radiation could activate STAT3, which subsequently promotes the invasion of A549 cells. We here explored the dose- and time-response of STAT3 to radiation and the effect of radiation on upstream signaling molecules.
  
  
  METHODS
  A549 cells were irradiated with different doses of γ-rays. The expression of and nucleus translocation of p-STAT3 in A549 cells were detected by immunoblotting and immunofluorescence, respectively. The level of phosphorylated EGFR was also assessed by immunoblotting, and IL-6 expression was detected by real time PCR and ELISA.
  
  
  RESULTS
  Radiation promoted the phosphorylation of STAT3 at Y705 in a dose- and time-dependent manner and nuclear translocation. The level of phosphorylated EGFR in A549 cells increased after radiation. In additional, the mRNA and protein levels of IL-6 in A549 cells were also up regulated by radiation.
  
  
  CONCLUSIONS
  STAT3 is activated by radiation in a dose-and time-dependent manner, probably due to radiation-induced activation of EGFR or secretion of IL-6 in A549 cells.
authors.affiliation: Key Laboratory of Radiological Protection and Nuclear Emergency, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing, China E-mail : suxu@nirp.cn, qjliu@nirp.cn.
authors.forename: Ling
authors.initials: L
authors.lastname: Gao
authors.forename: Feng-Sheng
authors.initials: FS
authors.lastname: Li
authors.forename: Xiao-Hua
authors.initials: XH
authors.lastname: Chen
authors.forename: Qiao-Wei
authors.initials: QW
authors.lastname: Liu
authors.forename: Jiang-Bin
authors.initials: JB
authors.lastname: Feng
authors.forename: Qing-Jie
authors.initials: QJ
authors.lastname: Liu
authors.forename: Xu
authors.initials: X
authors.lastname: Su
mesh_terms: D015153:Blotting, Western; D049109:Cell Proliferation / Q000528:radiation effects*; D003037:Cobalt Radioisotopes; D005455:Fluorescent Antibody Technique; D005720:Gamma Rays; D015972:Gene Expression Regulation, Neoplastic / Q000528:radiation effects*; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy*; D010766:Phosphorylation / Q000528:radiation effects; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000528:radiation effects*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
chemical_list: D003037:Cobalt Radioisotopes; D015850:Interleukin-6; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human