Abstract:

Objective　To study the expression and significance of p65 which is an important subtype of nuclear transcription factorκB (NF-κB) and its inhibitory protein IκBαin malignant transformation of hamster buccal mucosa.Methods　The animal model of malignant transformation in hamster buccal mucosa induced by DMBA(0.5%) was established. Twelve paired specimens including normal buccal mucosa, epithelial hyperplasia, epithelial dysplasia and squamous cell carcinoma (SCC) were subjected to Western blot for the analysis of p65.The expression of IκBαwas observed in 22 normal buccal epithelia, 20 hyperplasia epithelia, 35 dysplasia epithelia and 23 SCC by immunohistochemical evaluation.Results　In normal buccal epithelia and hyperplasia ep- ithelia, the expression of p65 was not obvious, and there was no significant difference between them(P>0.05).The expression of IκBαexisted at large, but mostly localizing in cell cytoplasmic staining in the basal cell layer and bottom of spinocelluar layer. With the occurrence of epithelia dysplasia,the expression of p65 gradually increased,comparing with normal buccal epithelia and hyperplasia epithelia(P<0.01). But the positive intensity of IκBαwas dramatically decreased(P<0.05). In SCC, p65 ex- pressed at a higher level comparingwith normal buccal mucosa and dysplasia(P<0.01), while the staining of IκBαwas feedback- ly higher comparing with dysplasia(P<0.01) and even with normal buccal mucosa(P<0.01).Conclusion　NF-κB p65 is strongly activated in malignant transformation of hamster buccal mucosa. The abnormal expression of p65 and IκBα,especially the ascending expression of p65 as well as the descending expression of IκBαin dysplasia may be an early event during oral carcino- genesis, and can be used as biomarkers for supervising oral malignancy.

Key words: squamous cell carcinoma, epithelial dysplasia, epithelial hyperplasia, nuclear transcription factorκB