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

Abstract

Elucidation of the molecular mechanism of radiation-induced activation of src kinase, which initiates EGFR internalization and nuclear transport. 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. 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. HNE generated in response to radiation exposure activates src kinase and is involved in regulation of radiation-stimulated DNA-repair processes.