Expression of cyclooxygenase-1 and cyclooxygenase-2 in bronchial epithelium and nonsmall cell lung carcinoma

BACKGROUND. Cyclooxygenase (Cox) is the main target enzyme for the nonsteroidal antiinflammatory drugs that have been shown to suppress carcinogenesis in both experimental models and epidemiologic studies. METHODS. To evaluate its utility as an intermediate biomarker in bronchial chemoprevention trials, the authors examined Cox 1 and Cox 2 expression in normal and premalignant bronchial epithelial cells and nonsmall cell lung carcinoma (NSCLC) samples using an immunohistochemical staining technique. Included in the current study were 101 NSCLC samples and 77 bronchial biopsy samples obtained from 15 healthy smokers. RESULTS. In the normal bronchial epithelium, Cox 2 expression was found to be completely negative whereas Cox 1 expression was noted in a few scattered cells. The areas of basal cell hyperplasia and squamous metaplasia demonstrated the same pattern. There were relatively more Cox 2-positive tumors, as defined by positive staining in > 10% of tumor cells, than Cox 1-positive tumors (30 of 101 tumors [30%] vs. 14 of 101 tumors [14%]; P = 0.01). When tumor types were considered, there were more Cox 2-positive adenocarcinomas compared with squamous cell carcinomas (21 of 51 adenocarcinomas [41%] vs. 9 of 46 squamous cell carcinomas [20%]; P = 0.03). In contrast, fewer adenocarcinomas tended to show Cox 1 expression compared with squamous cell carcinomas (4 of 51 adenocarcinomas [8%] vs. 9 of 46 squamous cell carcinomas [20%]; P = 0.14). Although smokers tended to have more Cox 2-positive tumors than nonsmokers (29 of 91 tumors in the smokers [32%] vs. 1 of 10 tumors in the nonsmokers [10%]; P = 0.15), there was no statistically significant relation found between Cox 1 or Cox 2 expression and smoking status or prognostically significant clinicopathologic features. CONCLUSIONS. The results of the current study suggest that Cox 1 and Cox 2 expression may not be a useful intermediate biomarker in bronchial chemoprevention trials. Nevertheless, considering the patterns of Cox 1 and Cox 2 expression in tumor cells, Cox expression status may be a useful parameter when designing treatment strategies for a subset of NSCLC patients.