Multilayered epithelium in a rat model and human Barrett's esophagus: similar expression patterns of transcription factors and differentiation markers

Abstract

Background: In rats, esophagogastroduodenal anastomosis (EGDA) without concomitant chemical carcinogen treatment leads to gastroesophageal reflux disease, multilayered epithelium (MLE, a presumed precursor in intestinal metaplasia), columnar-lined esophagus, dysplasia, and esophageal adenocarcinoma. Previously we have shown that columnar-lined esophagus in EGDA rats resembled human Barrett's esophagus (BE) in its morphology, mucin features and expression of differentiation markers (Lab. Invest. 2004;84:753-765). The purpose of this study was to compare the phenotype of rat MLE with human MLE, in order to gain insight into the nature of MLE and its potential role in the development of BE.

Methods: Serial sectioning was performed on tissue samples from 32 EGDA rats and 13 patients with established BE. Tissue sections were immunohistochemically stained for a variety of transcription factors and differentiation markers of esophageal squamous epithelium and intestinal columnar epithelium.

Results: We detected MLE in 56.3% (18/32) of EGDA rats, and in all human samples. As expected, both rat and human squamous epithelium, but not intestinal metaplasia, expressed squamous transcription factors and differentiation markers (p63, Sox2, CK14 and CK4) in all cases. Both rat and human intestinal metaplasia, but not squamous epithelium, expressed intestinal transcription factors and differentiation markers (Cdx2, GATA4, HNF1alpha, villin and Muc2) in all cases. Rat MLE shared expression patterns of Sox2, CK4, Cdx2, GATA4, villin and Muc2 with human MLE. However, p63 and CK14 were expressed in a higher proportion of rat MLE compared to humans.

Conclusion: These data indicate that rat MLE shares similar properties to human MLE in its expression pattern of these markers, not withstanding small differences, and support the concept that MLE may be a transitional stage in the metaplastic conversion of squamous to columnar epithelium in BE.

Figure 1

Expression of squamous transcription factors (p63, Sox2) and differentiation markers (CK4, Ck14) in squamous epithelium, MLE and IM of EGDA rats and humans. All the tissue sections were stained immunohistochemically with a specific antibody, and then histochemically with Alcian blue. Light blue: Alcian blue staining of acidic mucin; dark blue: hematoxylin staining for nuclei; dark brown: immunohistochemical staining. Size bar equals 20 μm in rat samples, or 40 μm in human samples.

Figure 2

Expression of intestinal transcription factors (Cdx2, GATA4, HNF1α) and differentiation markers (villin, Muc2) in MLE and IM of EGDA rats and humans. All the tissue sections were stained immunohistochemically with a specific antibody, and then histochemically with Alcian blue. Light blue: Alcian blue staining of acidic mucin; dark blue: hematoxylin staining for nuclei; dark brown: immunohistochemical staining. Size bar equals 20 μm in rat samples, or 40 μm in human samples.