Abstract: To study the expression of fibronectin(FN) in oral leukoplakia(OLK). Methods: Fibroblast and epithelial cells of normal oral mucosa and OLK were cultured in vitro. The level of FN in medium was detected by using ELISA method. The distribution of FN in tissues of normal oral mucosa, OLK and oral squamous cell carcinoma (OSCC) was observed by means of inmmunohistochemistry. The expression of FN in fibroblast and epithelial cells of normal oral mucosa and OLK was observed by using RTPCR technique. Results: The level of FN in medium of OLK fibroblast was lower than that of normal oral mucosa fibroblast markedly by ELISA (P<0.01); the level of FN was not markedly different between epithelium of OLK and normal oral mucosa. The result of RTPCR indicated that the expression of FN was obviously derogated in OLK fibroblast. The result of inmmunohistochemistry showed that the expression of FN in OLK epidermas and connective tissues declined incoordinately compared with normal oral mucosa and the distribution was different in them, but the degree of lesion in OLK was lower than that in OSCC. Conclusion: It is significant that the expression and different distribution of FN in OLK lead to OSCC. This provides a new way for treating OLK and interdicting OLK cancerization.

Key words: Mouth mucosa, Leukoplakia, oral, Fibronectin