Sequential expression of inducible nitric oxide synthase and cyclooxygenase-2 during DMBA-induced hamster buccal pouch carcinogenesis.

BACKGROUND

Although it is known that iNOS and COX-2 are abundantly expressed in oral premalignant and malignant lesions, respectively, the interaction between iNOS and COX-2 has not been extensively studied. The purpose of this study was to examine the alteration of the iNOS and COX-2 expression level during hamster buccal pouch (HBP) carcinogenesis.

MATERIALS AND METHODS

The expression of both iNOS and COX-2 on normal, dysplastic mucosa and squamous cell carcinoma (SCC) from different differentiation stages in 7, 12-dimethylbenz[a]anthracene (DMBA)-induced HBP carcinogenesis was examined using immunohistochemical analysis.

RESULTS

The mean values of both iNOS and COX-2 expression increased gradually from control to dysplastic lesions and more to invasive SCC. The highest mean expression was SCC. The differences between both iNOS and COX-2 expression in the normal and that in the dysplastic and carcinoma lesions were statistically significant.

CONCLUSION

The results suggest that iNOS can enhance its ability to promote tumor growth in cooperation with COX-2. The expression of iNOS and COX-2 may be one of the factors that contribute to oral carcinogenesis.