부산대학교 도서관

Gastroesophageal reflux is associated with adenocarcinoma in Barretrs esophagus, but the incidence of this tumor is rising, despite widespread use of acid-suppressing medications. This suggests that refluxed material other than acid might contribute to carcinogenesis. We looked for potentially carcinogenetic effects of two bile acids, deoxycholic acid (DCA) and ursodeoxycholic acid (UDCA), on Barrett's epithelial cells in vitro and in vivo. We exposed Barrett's (BAR-T) cells to DCA or UDCA and studied the generation of reactive oxygen/nitrogen species (ROS/ RNS); expression of phosphorylated H2AX (a marker of DNA damage), phosphorylated IkB[alpha], and phosphorylated p65 (activated NF-KB pathway proteins); and apoptosis. During endoscopy in patients, we took biopsy specimens of Barretrs mucosa before and after esophageal perfusion with DCA or UDCA and assessed DNA damage and NF-[kappa]B activation. Exposure to DCA, but not UDCA, resulted in ROS/RNS production, DNA damage, and NF-[kappa]B activation but did not increase the rate of apoptosis in BAR-T cells. Pretreatment with N-acetyl-L-cysteine (a ROS scavenger) prevented DNA damage after DCA exposure, and DCA did induce apoptosis in cells treated with NF-[kappa]B inhibitors (BAY 11-7085 or AdI[kappa]B superrepressor). DNA damage and NF-[kappa]B activation were detected in biopsy specimens of Barrett's mucosa taken after esophageal perfusion with DCA, but not UDCA. These data show that, in Barretrs epithelial cells, DCA induces ROS/RNS production, which causes genotoxic injury, and simultaneously induces activation of the NF-[kappa]B pathway, which enables cells with DNA damage to resist apoptosis. We have demonstrated molecular mechanisms whereby bile reflux might contribute to carcinogenesis in Barrett's esophagus. Barretrs esophagus; bile salts; gastroesophageal reflux doi: 10.1152/ajpgi.00092.2011