Expression of αvβ6 integrin in oral leukoplakia

The distribution of alpha(v)beta(6) integrin was examined in oral leukoplakia, lichen planus and squamous cell carcinomas using immunohistochemistry. Controls included oral mucosal wounds, chronically inflamed and normal oral mucosa. Integrins beta(1), beta(3), beta(4), beta(5), fibronectin and tenascin were also studied. The integrin alpha(v)beta(6) was highly expressed throughout the whole lesion of 90% of the squamous cell carcinomas but was not present in any of the normal specimens. alpha(v)beta(6) integrin was also expressed in 41% of the leukoplakia specimens, and 85% of the lichen planus samples, but in none of the tissues with inflammatory hyperplasia or chronic inflammation. The expression of beta 1 integrins was localized in the basal layer, and that of the beta(4) at the cell surface facing the basement membrane of all specimens. The integrins beta(3) and beta(5) were absent from all normal and leukoplakia specimens. Fibronectin and tenascin were present in the connective tissue underneath the epithelium of all the sections, and their expression was similar in both alpha(v)beta(6)-positive and alpha(v)beta(6)-negative tissues. A group of 28 leukoplakia patients were followed 1-4 years after first diagnosis. In this group, initially gp, integrin-positive leukoplakia specimens had high tendency for disease progression while alpha(v)beta(6)-negative specimens did not progress. These results suggest that the expression of alpha(v)beta(6) integrin could be associated in the malignant transformation of oral leukoplakias. (C) 2000 Cancer Research Campaign.