Objective In previous studies using oesophageal squamous cells from patients with Barrett's oesophagus (normal oesophageal squamous (NES)-B cells) and from patients without Barrett's oesophagus (NES-G cells), we showed that acid and bile salts induced caudal-related homeobox transcription factor 2 (CDX2) expression only in NES-B cells. CDX2, a transcription factor required to form intestinal epithelium, is a target of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signalling, which can be inhibited by aspirin. We explored mechanisms underlying differences between NES-B and NES-G cells in CDX2 expression and effects of aspirin on that CDX2 expression.
Design We exposed NES-B and NES-G cells to acid and bile salts, with and without aspirin, and evaluated effects on IκB-NF-κB-PKAc complex activation, p65 NF-κB subunit function, and CDX2 expression.
Results In both NES-B and NES-G cells, acid and bile salts activated nicotinamide adenine dinucleotide phosphate oxidase to generate H2O2, which activated the IκB-NF-κB-PKAc complex. NES-B cells exhibited higher levels of phosphorylated IκB and p65 and greater NF-κB transcriptional activity than NES-G cells, indicating greater IκB-NF-κB-PKAc complex activation by acid and bile salts in NES-B cells, and p65 siRNA prevented their increased expression of CDX2. Aspirin blocked IκB phosphorylation, p65 nuclear translocation, CDX2 promoter activation and CDX2 expression induced by acid and bile salts in NES-B cells.
Conclusions Differences between NES-B and NES-G cells in NF-κB activation by acid and bile salts can account for their differences in CDX2 expression, and their CDX2 expression can be blocked by aspirin. These findings might explain why some patients with GORD develop Barrett's oesophagus while others do not, and why aspirin might protect against development of Barrett's oesophagus.
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Contributors XH: study design; technical and material support; analysis and interpretation of data; critical revision of manuscript; important intellectual content; and drafting of manuscript. XZ, CY, EC, QZ, KBD, THP, JPL and DHW: technical and material support; important intellectual content. RSB: study concept; critical revision of manuscript and important intellectual content. SJS: study concept; analysis and interpretation of data; critical revision of manuscript and important intellectual content. RFS: study concept/design; analysis and interpretation of data; critical revision of manuscript; important intellectual content and drafting of manuscript.
Funding This work was supported by Merit Review Award #BX002666 from the U.S. Department of Veterans Affairs Biomedical Laboratory Research Program (SJS), the National Institutes of Health (R01-DK63621 and R01-DK103598 to RFS and SJS; K12 HD-068369 and K08-DK099383 to EC; R01-DK097340 to DHW; NCI N01-CN-05014-69 (TO-RFP S-2014 MDA2013-02-02 to RSB; NCI BETRNet program CA163004 and Career Development Award OD 012097 to JPL; and the American Gastroenterological Association June and Donald O. Castell Esophageal Clinical Research Award (to KBD);
Disclaimer The contents do not represent the views of the U.S. Department of Veterans Affairs or the US government.
Competing interests None declared.
Ethics approval These studies were approved by the Institutional Review Board of the Dallas VA Medical Center.
Provenance and peer review Not commissioned; externally peer reviewed.
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