Radiation-induced lipid peroxidation activates src kinase and triggers nuclear EGFR transport

Purpose: Elucidation of the molecular mechanism of radiation-induced activation of src kinase, which initiates EGFR internalization and nuclear transport. Material and 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 gamma H(2)AX-foci analysis. Rachation-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 24 h 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. (C) 2009 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 92 (2009) 379-382