Aberrant epithelial-mesenchymal Hedgehog signaling characterizes Barrett's metaplasia.
OBJECTIVE
The molecular mechanism underlying epithelial metaplasia in Barrett's esophagus remains unknown. Recognizing that Hedgehog signaling is required for early esophageal development, we sought to determine if the Hedgehog pathway is reactivated in Barrett's esophagus, and if genes downstream of the pathway could promote columnar differentiation of esophageal epithelium.


METHODS
Immunohistochemistry, immunofluorescence, and quantitative real-time polymerase chain reaction were used to analyze clinical specimens, human esophageal cell lines, and mouse esophagi. Human esophageal squamous epithelial (HET-1A) and adenocarcinoma (OE33) cells were subjected to acid treatment and used in transfection experiments. Swiss Webster mice were used in a surgical model of bile reflux injury. An in vivo transplant culture system was created using esophageal epithelium from Sonic hedgehog transgenic mice.


RESULTS
Marked up-regulation of Hedgehog ligand expression, which can be induced by acid or bile exposure, occurs frequently in Barrett's epithelium and is associated with stromal expression of the Hedgehog target genes PTCH1 and BMP4. BMP4 signaling induces expression of SOX9, an intestinal crypt transcription factor, which is highly expressed in Barrett's epithelium. We further show that expression of Deleted in Malignant Brain Tumors 1, the human homologue of the columnar cell factor Hensin, occurs in Barrett's epithelium and is induced by SOX9. Finally, transgenic expression of Sonic hedgehog in mouse esophageal epithelium induces expression of stromal Bmp4, epithelial Sox9, and columnar cytokeratins.


CONCLUSIONS
Epithelial Hedgehog ligand expression may contribute to the initiation of Barrett's esophagus through induction of stromal BMP4, which triggers reprogramming of esophageal epithelium in favor of a columnar phenotype.
Wang
David H
DH
Graduate Training Program in Cellular and Molecular Medicine, Johns Hopkins University, Baltimore, Maryland, USA. DavidH.Wang@VA.gov
Clemons
Nicholas J
NJ
Miyashita
Tomoharu
T
Dupuy
Adam J
AJ
Zhang
Wei
W
Szczepny
Anette
A
Corcoran-Schwartz
Ian M
IM
Wilburn
Daniel L
DL
Montgomery
Elizabeth A
EA
Wang
Jean S
JS
Jenkins
Nancy A
NA
Copeland
Neal A
NA
Harmon
John W
JW
Phillips
Wayne A
WA
Watkins
D Neil
DN
D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology; D000818:Animals; D001471:Barrett Esophagus / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D001646:Bile / Q000378:metabolism; D001655:Bile Reflux / Q000150:complications / Q000378:metabolism; D055415:Bone Morphogenetic Protein 4 / Q000378:metabolism; D002135:Calcium-Binding Proteins; D002450:Cell Communication / Q000235:genetics; D002454:Cell Differentiation; D002460:Cell Line; D004268:DNA-Binding Proteins; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000378:metabolism* / Q000473:pathology; D004938:Esophageal Neoplasms / Q000378:metabolism* / Q000473:pathology; D004947:Esophagus / Q000378:metabolism* / Q000473:pathology; D005764:Gastroesophageal Reflux / Q000150:complications / Q000378:metabolism; D053823:Hedgehog Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007633:Keratins / Q000378:metabolism; D008648:Mesoderm / Q000378:metabolism* / Q000473:pathology; D008679:Metaplasia; D051379:Mice; D008822:Mice, Transgenic; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D010641:Phenotype; D011230:Precancerous Conditions / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D034622:RNA Interference; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D055758:SOX9 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D014162:Transfection; D025521:Tumor Suppressor Proteins
C525809:BMP4 protein, human; C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D002135:Calcium-Binding Proteins; C108174:DMBT1 protein, human; D004268:DNA-Binding Proteins; D053823:Hedgehog Proteins; C000606236:PTCH1 protein, human; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; C000606240:Ptch1 protein, mouse; D011956:Receptors, Cell Surface; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; C465570:Shh protein, mouse; C527933:Sox9 protein, mouse; D025521:Tumor Suppressor Proteins; D007633:Keratins