title: Function of erbB receptors and DNA-PKcs on phosphorylation of cytoplasmic and nuclear Akt at S473 induced by erbB1 ligand and ionizing radiation.
abstract: OBJECTIVE
  In the present study effect of erbB2 as well as DNA-PKcs on ionizing radiation (IR)- and erbB1 ligand-induced phosphorylation of Akt at S473 in cytoplasmic and nuclear fractions was investigated.
  
  
  METHODS
  DNA-PKcs proficient and deficient syngeneic colon carcinoma sublines of HCT116 and the glioblastoma cell lines MO59K and MO59J as well as the lung carcinoma cell line A549 were used. Akt-S473 phosphorylation was investigated in cells pre-treated with pharmacological inhibitors or transfected with siRNA by immunoprecipitation, Western blotting and confocal microscopy after different stimuli, i.e., ligands and IR.
  
  
  RESULTS
  IR-induced phosphorylation of Akt in both MO59K and MO59J cell lines but not in HCT116 cells was DNA-PKcs dependent. In A549 cells, IR-induced phosphorylation of nuclear Akt-S473 was dependent on erbB1, erbB2, and DNA-PKcs. EGF induced phosphorylation of nuclear Akt-S473 in a DNA-PKcs and erbB2 independent manner.
  
  
  CONCLUSIONS
  Data indicate that the function of DNA-PKcs on IR-induced Akt-S473 phosphorylation is cell line specific. IR-induced, but not EGF-induced phosphorylation of cytoplasmic and/or nuclear Akt-S473 is erbB2 dependent.
authors: Division of Radiobiology and Molecular Environmental Research, Eberhard Karls University, Tuebingen, Germany.
authors: Mahmoud
authors: M
authors: Toulany
authors: Tim-Andre
authors: TA
authors: Schickfluss
authors: Kazi R
authors: KR
authors: Fattah
authors: Kyung-Jong
authors: KJ
authors: Lee
authors: Benjamin P C
authors: BP
authors: Chen
authors: Birgit
authors: B
authors: Fehrenbacher
authors: Martin
authors: M
authors: Schaller
authors: David J
authors: DJ
authors: Chen
authors: H Peter
authors: HP
authors: Rodemann
mesh_terms: D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D003110:Colonic Neoplasms / Q000235:genetics / Q000532:radiotherapy; D003593:Cytoplasm / Q000378:metabolism; D051747:DNA-Activated Protein Kinase / Q000378:metabolism* / Q000528:radiation effects; D005453:Fluorescence; D005909:Glioblastoma / Q000235:genetics / Q000532:radiotherapy; D006801:Humans; D008024:Ligands; D008175:Lung Neoplasms / Q000235:genetics / Q000532:radiotherapy; D009687:Nuclear Proteins / Q000378:metabolism* / Q000528:radiation effects; D010766:Phosphorylation / Q000187:drug effects / Q000528:radiation effects*; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011839:Radiation, Ionizing; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism* / Q000528:radiation effects; D012680:Sensitivity and Specificity; D015398:Signal Transduction; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000528:radiation effects*
chemical_list: D051747:DNA-Activated Protein Kinase; D008024:Ligands; D009687:Nuclear Proteins; D051057:Proto-Oncogene Proteins c-akt; D018719:Erb-b2 Receptor Tyrosine Kinases; C497263:PRKDC protein, human