OBJECTIVESTo investigate the expression of cyclooxygenase-2 (cox-2) protein in normal squamous epithelium, squamous dysplasia and squamous cell carcinoma of the esophagus, and to elucidate the role of cox-2 in esophageal carcinogenesis.

METHODSBiopsy specimens of atypical esophageal dysplasia (n = 47) and surgical resection of squamous cell carcinoma (n = 86) were compared with normal esophageal specimens (n = 42) and the expression of cox-2 in those specimens was analyzed by immunohistochemistry and western blotting.

RESULTSA significant elevated cox-2 expression was shown in atypical esophageal squamous dysplasia and squamous cell carcinoma, as compared to that in normal esophageal squamous epithelium, with immunohistochemical stain scores of 2.67 +/- 1.77, 2.19 +/- 1.79 and 0.71 +/- 0.46, respectively. Results of western blotting analysis confirmed those obtained by immunohistochemistry. Cox-2 expression significantly correlated with proliferation activity assessed by proliferating cell nuclear antigen index in dysplastic and carcinomous lesions, respectively, and no such correlation could be found in normal esophageal mucosa. Elevated cox-2 expression was not associated with clinical-pathological features of esophageal squamous carcinoma, including age, gender, tumor size, histological grade, lymph node metastasis and clinical stage.

CONCLUSIONElevated expression of cox-2 in atypical squamous dysplasia and squamous cell carcinoma of the esophagus, which correlated with cell proliferation activity, indicated that cox-2 may be involved in the early stage of squamous carcinogenesis of the esophagus, and may be a target of prevention and treatment for esophageal squamous cell carcinoma.