Radiofrequency ablation for dysplasia in Barrett's esophagus restores ß-catenin activation within esophageal progenitor cells.

ABSTRACT

BACKGROUND AND AIMS: Endoscopic therapies for Barrett's esophagus (BE) associated dysplasia, particularly radiofrequency ablation (RFA), are popular alternatives to surgery. The effect of such therapies on dysplastic stem/progenitor cells (SPC) is unknown. Recent studies suggest that AKT phosphorylation of ß-Catenin occurs in SPCs and may be a marker of activated SPCs. We evaluate the effect of RFA in restoring AKT-mediated ß-Catenin signaling in regenerative epithelium. METHODS: Biopsies were taken from squamous, non-dysplastic BE, dysplastic BE and esophageal adenocarcinoma (EAC). Also, post-RFA, biopsies of endoscopically normal appearing neosquamous epithelium were taken at 3, 6, and 12 months after successful RFA. Immunohistochemistry and Western blot analysis was performed for Pß-Catenin(552) (Akt-mediated phosphorylation of ß-Catenin), Ki-67 and p53. RESULTS: There was no difference in Pß-Catenin552 in squamous, GERD, small bowel and non-dysplastic BE. There was a fivefold increase in Pß-Catenin(552) in dysplasia and EAC compared to non-dysplastic BE (P < 0.05). Also, there was a persistent threefold increase in Pß-Catenin(552) in neosquamous epithelium 3 months after RFA compared to native squamous epithelium (P < 0.05) that correlated with increased Ki-67. Six months after RFA, Pß-Catenin(552) and Ki-67 are similar to native squamous epithelium. CONCLUSIONS: Enhanced AKT-mediated ß-Catenin activation is seen in BE-associated carcinogenesis. Three months after RFA, squamous epithelial growth from SPC populations exhibited increased levels of Pß-Catenin(552). This epithelial response becomes quiescent at 6 months after RFA. These data suggest that elevated Pß-Catenin(552) after RFA denotes a repair response in the neosquamous epithelium 3 months post-RFA.