Bile acids directly augment caudal related homeobox gene Cdx2 expression in oesophageal keratinocytes in Barrett’s epithelium

• Published in: Gut Vol. 55; no. 1; pp. 16 - 25
• Main Authors: Kazumori, H, Ishihara, S, Rumi, M A K, Kadowaki, Y, Kinoshita, Y
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd and British Society of Gastroenterology 01-01-2006; BMJ; BMJ Publishing Group LTD; BMJ Group
• Subjects: Acids; Animals; Barrett Esophagus - metabolism; Barrett Esophagus - pathology; Barrett’s oesophagus; Bile; bile acid; Bile Acids and Salts - analysis; Bile Acids and Salts - pharmacology; Biological and medical sciences; Blotting, Northern; CDCA; Cdx2; CDX2 Transcription Factor; Cells, Cultured; chenodeoxycholic acid; cholic acid; Cholic Acid - pharmacology; cytokeratin; DCA; dehydrocholic acid; deoxycholic acid; DHCA; Disease Models, Animal; electrophoretic mobility shift assay; EMSA; Esophagus; gastro-oesophageal reflux disease; Gastroenterology. Liver. Pancreas. Abdomen; Gastrointestinal Contents - chemistry; GCA; GCANa; GCDCA; Gene Expression Regulation - drug effects; Genes, Homeobox - drug effects; Genes, Reporter; glycochenodeoxycholic acid; glycocholic acid; GORD; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Humans; Keratinocytes - drug effects; Keratinocytes - metabolism; kilobase; LCA; lithocholic acid; Male; Medical sciences; NFκB; nuclear factor κB; Oesophagus; Other diseases. Semiology; Promoter Regions, Genetic; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction - methods; reverse transcription-polymerase chain reaction; Rodents; RT-PCR; Small intestine; sodium salt; Studies; taurochenodeoxycholic acid; taurocholic acid; taurodeoxycholic acid; TCA; TCDCA; TDCA; Premalignant lesion; Bile acid; Esophageal disease; Gastroenterology; Digestive diseases; Barrett esophagus; Gene expression
• ISSN: 0017-5749; 1468-3288
• DOI: 10.1136/gut.2005.066209

Background and aims: The mechanism of transformation to intestinal metaplasia in Barrett’s oesophagus has not been clarified. We investigated the effects of various bile acids on expression of the caudal related homeobox gene Cdx2 in cultured oesophageal squamous epithelial cells. In addition, morphological and histochemical changes in squamous cells to intestinal epithelial cells were studied in response to bile acid induced expression of Cdx2. Methods: A rat model of Barrett’s oesophagus was created by anastomosing the oesophagus and jejunum, and Cdx2 expression was investigated by immunohistochemistry. Also, the response of various bile acids on Cdx2 gene expression was studied in the human colon epithelial cell lines Caco-2 and HT-29, as well as in cultured rat oesophageal squamous epithelial cells using a Cdx2 promoter luciferase assay. In addition, primary cultured oesophageal squamous epithelial cells were transfected with Cdx2 expression vectors and their possible transformation to intestinal-type epithelial cells was investigated. Results: Oesophagojejunal anastomoses formed intestinal goblet cell metaplasia in rat oesophagus specimens and metaplastic epithelia strongly expressed Cdx2. When the effects of 11 types of bile acids on Cdx2 gene expression were examined, only cholic acid (CA) and dehydrocholic acid dose dependently increased Cdx2 promoter activity and Cdx2 protein production in Caco-2 and HT-29 cells, and cultured rat oesophageal keratinocytes. Results from mutation analysis of Cdx2 promoter suggested that two nuclear factor κB (NFκB) binding sites were responsible for the bile acid induced activation of the Cdx2 promoter. When bile acids were measured in oesophageal refluxate of rats with experimental Barrett’s oesophagus, the concentration of CA was found to be consistent with the experimental dose that augmented Cdx2 expression in vitro. Furthermore, transfection of the Cdx2 expression vector in cultured rat oesophageal keratinocytes induced production of intestinal-type mucin, MUC2, in cells that expressed Cdx2. Conclusions: We found that CA activates Cdx2 promoter via NFκB and stimulates production of Cdx2 protein in oesophageal keratinocytes with production of intestinal-type mucin. This may be one of the mechanisms of metaplasia in Barrett’s oesophagus.