Expression and function of the coxsackie and adenovirus receptor in Barrett's esophagus and associated neoplasia.

Cell surface presence of the coxsackie and adenovirus receptor (CAR) is considered a crucial prerequisite for the uptake of attenuated adenovirus. In cancers, however, a frequent loss of CAR has been noted potentially hampering the success of adenovirus-based therapy. In esophageal Barrett's carcinomas and its precursor lesions CAR presence has not been systematically determined yet. Immunohistochemical assessment in tissue specimens of 111 patients revealed CAR-positivity in all cases of Barrett's esophagus, including various degrees of intraepithelial neoplasia. In contrast, no considerable CAR presence was seen in squamous esophageal epithelium. Among Barrett's carcinomas, 93% displayed CAR presence, whereas CAR-negativity was observed preferentially in advanced cancers. Aiming to evaluate whether this loss of CAR impacts tumor-biologic properties of esophageal adenocarcinomas we studied cell lines OE19 and OE33 and observed an increased proliferation, migration and invasion upon siRNA-mediated functional CAR knock down. In conclusion, our results indicate that CAR may provide a valuable target for adenovirus-based therapy of Barrett's carcinomas and its precursor lesions. These data do also suggest that CAR does not contribute substantially to carcinogenesis in Barrett's esophagus, however, it may be speculated that loss of CAR promotes tumor progression in advanced stages of Barrett's carcinomas.