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Abstract
Non-steroidal anti-inflammatory drugs are well known with their cancer chemopreventive effects through inhibition of cyclooxygenase-2(cox-2) that is the principal key in prostaglandin production. One of cyclooxygenase-2 selective inhibitors is celecoxib. The objective was to study the effect of celecoxib on rat palatal tissues before, during and after 4-nitroquinoline 1-oxide (4NQO) carcinogen application. In the present study, fifty male albino rats were divided into five equal groups. The first group, negative control, was not subjected to any treatment. The second group, positive control, had 4NQO carcinogen application for 20 weeks. In the other three groups, rats were given celecoxib before, during and after 4NQO application. Immunohistochemical staining was used to demonstrate cox-2 expression. The results showed that cox-2 expression did not appear in normal tissues, but appeared in cases of dysplasia and squamous cell carcinoma (scc). The intensity of cox-2 expression increased with increasing degrees of dysplasia. Cox-2 expression was found more intense in well differentiated scc than dysplasias. Results revealed that celecoxib prevented carcinogenesis if used two weeks before application of 4NQO and it could inhibit the tumor growth if used during 4NQO application for 20 weeks and after 4NQO application for ten weeks.