Factors regulating nuclear factor-kappa B activation in esophageal cancer cells: Role of bile acids and acid.

Abstract

Gastroesophageal reflux disease is considered to be a major risk in the development of esophageal adenocarcinoma. Nuclear factor-kappa B (NF-κB) plays important roles in the regulation of several genes coding for cytokines, cell proliferation, and apoptosis. To understand the role of bile and acid in the causation of esophageal cancer, we have examined the effects of bile acids and acid on NF-κB activation in the esophageal epithelial cells OE33 and SKGT-4 qualitatively and quantitatively. Analysis of NF-κB activation in esophageal epithelial cells in response to bile acids and acid was performed by electrophoretic mobility shift assay, Western blotting and the translocation NF-κB was assessed by high content analysis (HCA). Cyclooxygenase-2 (COX-2) promoter activity was assessed by transient transfection assays. This study demonstrated that bile acids and acid activated NF-κB in a dose- and time-dependent manner. HCA analysis was an invaluable method in quantifying NF-κB translocation at the single cell population level following bile or acid treatment. Furthermore, deoxycholic acid (DCA) and acid-induced COX-2 promoter activity, and a mutation in the NF-κB and activator protein-1 (AP-1) binding sites remarkably reduced the reporter gene activity induced by DCA or acid. Our data demonstrate that bile and acid induce NF-κB activation in esophageal cells qualitatively and quantitatively. The induction of COX-2 promoter activity by DCA and acid was mediated via NF-κB and AP-1 transcription. The activation of NF-κB signaling pathway in esophageal cells may contribute to the development of esophageal cancer, and, therefore, modulating of NF-κB pathway may uncover new therapeutic strategies.