Prolonged activation of NF-kappa B is involved in the pathogenesis of chronic inflammatory diseases and associated cancers. NF-kappa B activation is considered to be a main mechanism opposing TNF alpha-induced apoptosis. We investigated whether inhibition of NF-kappa B could sensitize tumor and endothelial cells to TNF alpha-induced apoptosis. As such, we developed a novel HI RNA polymerase III promoter driven adenoviral vector to express an RNA aptamer, Ad-A-p50, which selectively inhibits NF-kappa B activation in the nucleus. This event sensitizes human lung adenocarcinoma cells (A549) and human endothelial cells (HUVEC) to TNF alpha-induced apoptosis through the multiple pathways regulated by NF-kappa B, including Bel-XL, HIF-1 alpha, and VEGF. Our findings also suggest a new mechanism of HIF-1 alpha regulation by NF-kappa B in the normoxic environment. RNA aptamer inhibition of NF-kappa B offers exciting opportunities for sensitizing inflammatory and tumor cells to TNF alpha-induced apoptosis. (c) 2007 Elsevier Inc. All rights reserved.