Radiation-induced lipid peroxidation activates src kinase and triggers nuclear EGFR transport.
OBJECTIVE
Elucidation of the molecular mechanism of radiation-induced activation of src kinase, which initiates EGFR internalization and nuclear transport.


METHODS
Radiation-induced src activation was investigated in the bronchial carcinoma cell line A549. Proteins were Western blotted and quantified by the help of specific antibodies. Residual DNA-damage was quantified with gammaH(2)AX-foci analysis. Radiation-induced lipid peroxidation was prevented by acetyl-cysteine.


RESULTS
The radiation-induced src activation and EGFR stabilization could be mimicked by addition of hydroxy-nonenal (HNE), one of the major lipid peroxidation products. Radiation-generated HNE is bound to EGFR and src and correlated with complex formation between both following radiation. Treatment with HNE activated src and stimulated radiation-associated EGFR and caveolin 1 phosphorylations resulting in increased nuclear transport of EGFR. Consequently, radiation-induced phosphorylation and activation of DNA-PK were increased. This phosphorylation was associated with improved removal of residual damage 24h after irradiation. Inhibition of radiation-induced HNE generation by acetyl-cysteine blocked radiation-induced src activation and EGFR phosphorylation.


CONCLUSIONS
HNE generated in response to radiation exposure activates src kinase and is involved in regulation of radiation-stimulated DNA-repair processes.
Dittmann
Klaus
K
Department of Radiation Oncology, Eberhard-Karls-University, Röntgenweg, Germany. klaus.dittmann@uni-tuebingen.de
Mayer
Claus
C
Kehlbach
Rainer
R
Rothmund
Marie-Christine
MC
Peter Rodemann
H
H
D021581:Active Transport, Cell Nucleus; D015153:Blotting, Western; D002283:Carcinoma, Bronchogenic / Q000473:pathology / Q000532:radiotherapy; D051242:Caveolin 1 / Q000378:metabolism*; D045744:Cell Line, Tumor / Q000378:metabolism / Q000528:radiation effects; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects; D004260:DNA Repair / Q000502:physiology*; D066246:ErbB Receptors / Q000378:metabolism* / Q000528:radiation effects; D006801:Humans; D015227:Lipid Peroxidation / Q000528:radiation effects*; D010766:Phosphorylation / Q000528:radiation effects; D011839:Radiation, Ionizing; D012680:Sensitivity and Specificity; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000528:radiation effects; D019061:src-Family Kinases / Q000378:metabolism* / Q000528:radiation effects
D051242:Caveolin 1; D066246:ErbB Receptors; D019061:src-Family Kinases