GATA4, expressed in Barrett's esophagus and esophageal adenocarcinoma, can block squamous epithelial cell gene expression in human esophageal cells

Metaplasia often involves a change from one cell type to another that was present during organogenesis. The embryonic esophagus is initially lined by columnar cells that are replaced by squamous cells, and metaplasia in Barretts esophagus (BE) involves a change from squamous to columnar cells in the setting of gastroesophageal reflux. Here, we explored the effect of ectopic expression of the essential developmental transcription factor GATA4 on squamous epithelial cell gene expression using human esophageal squamous epithelial cells. We found that GATA4 protein, although absent in mature human esophageal squamous epithelium, was present in BE and esophageal adenocarcinoma (EAC). Moreover, acid and bile induced GATA4 mRNA in esophageal squamous epithelial cells. Ectopic GATA4 expression in esophageal squamous epithelial cells generally compromised squamous cell marker gene expression, although the extent varied between cell lines studied. We observed GATA4 occupancy in the p63, KRT5, and KRT15 gene promoters, suggesting that GATA4 can directly repress expression of typical squamous epithelial cell marker genes. Overall, our data suggest a mechanism whereby GATA4 expression in abnormal esophageal cells, possibly induced by reflux, supports a columnar metaplastic cell identity by repressing expression of key genes required to program stratified squamous epithelial cell identity.