899 Transformation of Benign Barrett's Epithelial Cells By Repeated Acid and Bile Exposure Over 22-65 Weeks: An in-Vitro Model of Metaplasia to Neoplasia By Environmental Factors

Background and aims: Barrett's esophagus (BE) is regarded as pre-malignant condition of esophagus. The exact pathomechanisms responsible for the development Barrett's adenocarcinoma (BA) are still poorly understood. There is an evidence that the development of BE is a consequence of a chronic duodenogastroesophageal reflux disease (DGER) and ongoing inflammation in injured area of esophageal mucosa. The aims of the study were; 1) analysis of NFκB activity in human BE biopsies and influence of bile acids (DCA and UDCA) on its transactivation in BA cell line (OE-19 cells); 2) Implication of CDX-2 in BE development and the influence of bile acids on CDX-2 expression in OE-19 cell line; 3) Influence of siRNA-RelA (siRNA against NFκB) and a NFκB inhibitor (MG-132) on COX-2 and CDX-2 expressions in OE-19 cell line induced by bile salts. Material and Methods: CDX-2 and COX-2 was analysed in human biopsies from the normal esophagus mucosa and BE at mRNA and protein level by qRT-PCR and Western blot, respectively. Additionally, activity of NFκB in BE was assessed by ELISA. In separate In Vitro experiments, OE-19 cells were incubated with or without bile salts (DCA or UDCA, 100μM or 300μM) in neutral pH in the presence of MG-132 or after transfection with siRNA-RelA. The apoptosis rate was evaluated by FACS. The expression of COX-2 and CDX-2 was analyzed at mRNA and protein level by quantitative RT-PCR and immunoblot. Results: BE demonstrated a significant upregulation of CDX-2 and COX-2 expressions and elevated activity of NFκB as compared to normal esophagus. DCA compared to UDCA stronger stimulated COX-2 and CDX-2 expression in OE-19 cells. Both MG-132 and transfection with siRNA-RelA attenuated the increase in COX-2 and CDX-2 expression after treatment of the cells with DCA and induced higher rate of apoptosis. Conclusions: Bile salts are involved development of Barrett's metaplasia probably via direct stimulation of COX-2 and CDX2. These effects are mediated by increased activation of NFκB Thus, targeted therapy against NFκB may have beneficial preventive effect on the development of Barrett's adenocarcinoma.