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

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.

The effects of the Epstein-Barr virus latent membrane protein 2A on B cell function.

Epstein-Barr Virus (EBV) infects B-lymphocytes circulating through the oral epithelium and establishes a lifelong latent infection in a subset of mature-memory B cells. In these latently infected B cells, EBV exhibits limited gene expression with the latent membrane protein 2A (LMP2A) being the most consistently detected transcript. This persistent expression, coupled with many studies ofthe function of LMP2A in vitro and invivo, indicates that LMP2A is functioning to control some aspect of viral latency. Establishment and maintenance of viral latency requires exquisite manipulation of normal B cell signaling and function. LMP2A is capable of blocking normal B cell signal transduction in vitro, suggesting that LMP2A may act to regulate lytic activation from latency in vivo. Furthermore, LMP2A is capable of providing B cells with survival signals in the absence of normal BCR signaling. These data show that LMP2A may help EBV-infected cells to persist in vivo. This review discusses the advances that have been made in our understanding of LMP2A and the effects it has on B cell development, activation, and viral latency.