Blockage of either nuclear factor-kappa B (NF-kappa B) or Akt sensitizes cancer cells to TNF-induced apoptosis. In this study, we investigated the undetermined effect of concurrent blockage of these two survival pathways on TNF-induced cytotoxicity in lung cancer cells. The results show that Akt contributes to TNF-induced NF-kappa B activation in lung cancer cells through regulating phosphorylation of the p65/RelA subunit of NF-kappa B. Although individually blocking IKK or Akt partially suppressed TNF-induced NF-kappa B activation, concurrent suppression of these pathways completely inhibited TNF-induced NF-kappa B activation and downstream anti-apoptotic gene expression, and synergistically potentiated TNIF-induced cytotoxicity. Moreover, suppression of Akt inhibited the Akt-mediated anti-apoptotic pathway through dephosphorylation of BAD. These results indicate that concurrent suppression of NF-kappa B and Akt synergistically sensitizes TNF-induced cytotoxicity through blockage of distinct survival pathways downstream of NF-kappa B and Akt, which may be applied in lung cancer therapy. (c) 2007 Elsevier Inc. All rights reserved.