Expression of NF-κB and IL-6 in oral precancerous and cancerous lesions: An immunohistochemical study

The purpose of this study was to evaluate the immunohistochemical expression of NF-κB and IL-6 in oral premalignant and malignant lesions and to investigate their possible correlation with the presence of subepithelial inflammation. Thirty two oral premalignant lesions, clinically compatible with leukoplakia or erythroplakia, were investigated. Microscopically, 11 of them showed hyperkeratosis and acanthosis (epithelial hyperplasia) and 21 showed dysplasia of varying degrees. Nine cases of OSCC and four control cases of normal oral mucosa were also included in the study. Immunohistochemical staining with NF-κB (p65) and IL-6 was performed. IL-6 and nuclear NF-κB staining were assessed as positive or negative. For cytoplasmic localization of NF-κB, a total score combining intensity and percentage of positive epithelial cells was additionally calculated. The presence of inflammation was also recorded. Intensity and total scores for NF-κΒ cytoplasmic immunostaining showed a statistically significant gradual increase from normal mucosa to OSCC (p=0.012 and p=0.026 respectively). Non-statistically significant increased NF-κΒ nuclear localization was detected in dysplasias and OSCCs. Positive statistical correlation was detected between the presence of inflammation and IL-6 expression (p=0.015). No correlation between NF-κΒ and IL-6 was detected. NF-κΒ is activated in the early stages of oral carcinogenesis. IL-6 may have an NF-κΒ-independent role, possibly through regulation of the inflammatory response.