Nuclear factor κB and cyclooxygenase-2 immunoexpression in oral dysplasia and oral squamous cell carcinoma

Oral leukoplakia is the main potentially malignant oral lesion, and oral squamous cell carcinoma accounts for more than 95% of all malignant neoplasms in the oral cavity. Therefore, the aim of this study was to verify the immunoexpression of nuclear factor κB (NF-κB) and cyclooxygenase-2 (COX-2) proteins in dysplastic oral lesions and oral squamous cell carcinoma. Immunohistochemical reactions were performed on 6 inflammatory fibrous hyperplasia, 28 oral leukoplakia, and 15 oral squamous cell carcinoma paraffin-embedded samples. Immunoperoxidase reaction for NF-κB and COX-2 was applied on the specimens, and the positivity of the reactions was calculated for 1000 epithelial cells. Using the analysis of variance and the Tukey post hoc statistical analyses, a significantly increased immunoexpression for NF-κB was observed when oral squamous cell carcinoma samples were compared with the other groups studied. However, using the Kruskal-Wallis and the Dunn post hoc tests, a statistically significant result for COX-2 expression was obtained only when the moderate dysplasia group was compared with the inflammatory fibrous hyperplasia group. Nuclear factor κB may participate in the malignant phenotype acquisition process of the oral squamous cell carcinoma in its late stages, whereas COX-2 may be involved in the early stages of oral carcinogenesis process.