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Changes in the expression of Col IV, gelatinase and TIMP-1 in oral leukoplakia.

Type IV collagen (Col IV) is an important protein in the basement membrane (BM), which can regulate the attachment of epithelium and the lamina propria. To test the hypothesis that Col IV may play a significant role in the progression of oral leukoplakia, we have observed the morphology and distribution of Col IV in 40 patients with oral leukoplakia (epithelial hyperplasia and dysplasia). The results showed that the expression of Col IV in the BM was continuous in normal oral mucosa, while it was non-continuous or fragmented in epithelial dysplasia by immunofluorescent staining. Consequently, to analyze the correlated factors of the Col IV destruction, the expressions of gelatinase (MMP-2 and MMP-9) and tissue inhibitor of metalloproteinases -1 (TIMP-1) were detected in oral leukoplakia tissues by immunochemical staining. Then statistical analyses were performed to determine their correlations with Col IV levels. The statistics showed that the decreasing of Col IV was closely related to the increasing of MMP-9 in both epithelial hyperplasia and dysplasia (P < 0.05), while MMP-2 expression was closely related to the increasing of Col IV expression in epithelial dysplasia (P < 0.05). Therefore, monitoring changes in the expression of Col IV, gelatinase and TIMP-1 is a useful technique for assessing prognosis of oral leukoplakia.