ErbB2 without erbB3 expression in metaplastic columnar epithelium of Barrett's esophagus

ErbB2 expression in esophageal adenocarcinoma has been shown to correlate with its clinicopathological features. However, expression levels for EGF receptor, erbB2 and erbB3 in specialized columnar epithelium (SCE) of Barrett's esophagus have yet to be determined. To investigate the relationship between EGF family receptors and Barrett's esophagus, we examined expression levels for EGF receptor, erbB2 and erbB3 in SCE of Barrett's esophagus.

10 consecutive patients with short- and long-segment Barrett's esophagus, and 10 control subjects without organic esophago-gastric diseases were enrolled. Biopsy samples of Barrett's mucosa stained or not stained with methylene blue applied endoscopically were used for histological evaluation and Western blot analysis of EGF receptor, erbB2 and erbB3 proteins.

Mean length of Barrett's esophagus was 2.6 cm (range 1-8 cm) and all tissue samples from methylene blue stained Barrett's mucosa consisted of non-dysplastic SCE. In the Barrett's group, Western blot analysis showed that EGF receptor and erbB2 were equally and strongly expressed in SCE and squamous epithelium; in contrast, erbB3 expression in SCE was considerably weaker. In control subjects, all proteins showed strong expression for all samples. Immunohistochemical analysis of SCE in Barrett's esophagus showed positive EGF receptor and erbB2 expression, and no erbB3 expression.

ErbB2 is strongly expressed in both non-dysplastic SCE and squamous epithelium, whereas erbB3 expression is essentially limited to the squamous epithelium. .