This study aimed to identify pathways and cellular processes that are modulated by exposure of normal esophageal cells to bile and acid.
Barrett's esophagus most likely develops as a response of esophageal stem cells to the abnormal reflux environment. Although insights into the underlying molecular mechanisms are slowly emerging, much of the metaplastic process remains unknown.
We performed a global analysis of gene expression in normal squamous esophageal cells in response to bile or acid exposure. Differentially expressed genes were classified into major biological functions using pathway analysis and interaction network software. Array data were verified by quantitative PCR and western blot both in vitro and in human esophageal biopsies.
Bile modulated expression of 202 genes, and acid modulated expression of 103 genes. Genes involved in squamous differentiation formed the largest functional group (n = 45) all of which were downregulated by bile exposure. This included genes such as involucrin (IVL), keratinocyte differentiation-associated protein (KRTDAP), grainyhead-like 1 (GRHL1), and desmoglein1 (DSG1) the downregulation of which was confirmed by quantitative PCR and western blot. Bile also caused expression changes in genes involved in cell adhesion, DNA repair, oxidative stress, cell cycle, Wnt signaling, and lipid metabolism. Analysis of human esophageal biopsies demonstrated greatly reduced expression of IVL, KRTDAP, DSG1, and GRHL1 in metaplastic compared to squamous epithelia.
We report for the first time that bile inhibits the squamous differentiation program of esophageal epithelial cells. This, coordinated with induction of genes driving intestinal differentiation, may be required for the development of Barrett's esophagus.
[Show abstract][Hide abstract] ABSTRACT: Barrett's esophagus is a preneoplastic metaplasia in which the normal squamous epithelium of the esophagus changes to an intestinal, columnar phenotype due to long-term gastro-esophageal reflux. The major components of this reflux are bile and stomach acid. Previous in vitro studies on the effect of bile and acid on esophageal cells have predominantly relied on transformed esophageal squamous cells or cancer cells grown in monolayer culture.
In this study, we expanded our previous work using an immortalized primary esophageal squamous cell line (EPC1). We demonstrate that EPC1 cells form a multi-layer, stratified epithelium when grown on polyester transwell filters in media supplemented with calcium. When exposed to short pulses of bile and pH 5, but not either condition alone, EPC1 cells demonstrate a reduction in stratification layers and reduced expression of squamous epithelium-specific genes. Bile at pH 5 also causes activation of epidermal growth factor receptor and down-stream pathways. Blocking epidermal growth factor receptor activation partially attenuates the effects of bile acid and pH 5. These results suggest that bile at low pH, but not bile or low pH alone, promotes loss of differentiation status of stratified squamous esophageal epithelium in vitro, possibly by initiating a mucosal repair response through epidermal growth factor activation.
Journal of Gastrointestinal Surgery 08/2013; 17(10). DOI:10.1007/s11605-013-2287-1 · 2.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Proton pump inhibitors (PPI) may potentially modify and decrease the risk for development of oesophageal adenocarcinoma in Barrett's oesophagus (BO).
To investigate if the intensity and adherence of PPI use among all patients with BO in Denmark affected the risk of oesophageal adenocarcinoma.
We performed a nationwide case-control study in Denmark among 9883 patients with a new diagnosis of BO. All incident oesophageal adenocarcinomas and high-grade dysplasias were identified, and risk ratios were estimated on the basis of prior use of PPIs. Sex- and age-matched BO patients without dysplasia or malignancies in a 10:1 ratio were used for comparison. Conditional logistic regression was used for analysis, adjusting for low-grade dysplasia, gender and medication.
We identified 140 cases with incident oesophageal adenocarcinomas and/or high-grade dysplasia, with a median follow-up time of 10.2 years. The relative risk of oesophageal adenocarcinoma or high-grade dysplasia was 2.2 (0.7-6.7) and 3.4 (95% CI: 1.1-10.5) in long-term low- and high-adherence PPI users respectively.
No cancer-protective effects from PPI's were seen. In fact, high-adherence and long-term use of PPI were associated with a significantly increased risk of adenocarcinoma or high-grade dysplasia. This could partly be due to confounding by indication or a true negative effect from PPIs. Until the results from future studies hopefully can elucidate the association further, continuous PPI therapy should be directed at symptom control and additional modalities considered as aid or replacement.
[Show abstract][Hide abstract] ABSTRACT: Barrett's metaplasia of the esophagus (BE) is the precursor lesion of esophageal adenocarcinoma (EAC), a deadly disease with a 5-year overall survival of less than 20%. The molecular mechanisms of BE development and its transformation to EAC are poorly understood and current surveillance and treatment strategies are of limited efficacy. Increasing evidence suggests that aberrant signaling through pathways active in the embryological development of the esophagus contributes to BE development and progression to EAC. We discuss the role that the Bone morphogenetic protein, Hedgehog, Wingless-Type MMTV Integration Site Family (WNT) and Retinoic acid signaling pathways play during embryological development of the esophagus and their contribution to BE development and malignant transformation. Modulation of these pathways provides new therapeutic opportunities. By integrating findings in developmental biology with those from translational research and clinical trials, this review provides a platform for future studies aimed at improving current management of BE and EAC.
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