Expression of nitric oxide synthase type 3 in reflux-induced esophageal lesions

BACKGROUND: The expression of endothelial constitutive nitric oxide synthas e (NOS3) by squamous dysplasia and carcinomas of the head and neck has prev iously been described. We sought to compare NOS3 expression in squamous muc osa, glandular metaplasia, and adenocarcinoma of the esophagus. METHODS: Forty paraffin-embedded specimens from 20 patients with adenocarci noma were stained with anti-NOS3 monoclonal antibody. The percentage of cel ls stained and the intensity of staining were determined for squamous epith elium, metaplasia, and adenocarcinoma. Staining characteristics were statis tically analyzed according to clinical variables. RESULTS: NOS3 expression was significantly higher in adenocarcinoma and squ amous epithelium compared with glandular metaplasia. Among the carcinomas, larger tumor size (T3/4), nodal positivity, and advanced TNM stage (III/IV) significantly correlated with increased NOS3 expression. CONCLUSIONS: NOS3 is expressed in reflux-induced lesions of the esophagus, Glandular metaplasia shows basal levels of NOS3 that significantly increase with malignant transformation and tumor progression. The role of free radi cals in carcinogenesis is being actively studied.