4-hydroxynonenal triggers an epidermal growth factor receptor-linked signal pathway for growth inhibition

Lipid peroxidation has been implicated in the pathogenesis of various disea ses. As a major product of membrane lipid peroxidation, 4-hydroxynonenal (H NE) appears after various kinds of oxidative stress, and is known to induce cell growth inhibition. We here analysed the HNE-mediated signal transduct ion cascade for the growth inhibition of human epidermoid carcinoma A431 ce lls. HNE dose-dependently induced phosphorylation of multiple cellular prot eins including epidermal growth factor receptor (EGFR) in A431 cells, and r apidly upregulated the catalytic actions of EGFR for autophosphorylation an d for phosphorylation of casein as an exogenous substrate. Immunoblot analy sis by use of HNE-specific antibody demonstrated the binding of HNE to EGFR along with its activation. This binding, which did not induce cross-linkin g of EGFR, caused a capping of the receptor on the cell surface which mimic ked the capping induced by EGF. Phosphorylation and activation of EGFR were followed by phosphorylation of adaptor protein Shc and activation of MAP k inase. Both genistein as a wide spectrum protein tyrosine kinase inhibitor and AG1478 as a specific EGFR tyrosine phosphorylation blocker inhibited ac tivation of EGFR and MAP kinase by HNE. The same inhibitors prevented HNE-m ediated growth inhibition, suggesting a close linkage between EGFR/MAP kina se activation and growth inhibition after exposure to HNE. Our results sugg est that EGFR may be one of the primary targets of HNE for an oxidative str ess-linked cell growth inhibition.