ALTERATIONS IN EXPRESSION OF BASEMENT-MEMBRANE PROTEINS DURING TUMOR PROGRESSION IN ORAL-MUCOSA

Expression of three basement membrane proteins-collagen IV, laminin an d fibronectin-was studied in normal, hyperplastic, dysplastic and neop lastic conditions of the oral mucosa using immunohistochemistry. Colla gen IV and laminin exhibited similar staining patterns, while fibronec tin showed a different pattern of expression. The expression of collag en IV and laminin also demonstrated an inverse correlation between sta ining intensity, thickness and basement membrane continuity in various stages of tumour progression. In contrast to the continuous and inten se staining of basement membrane in normal oral mucosa with collagen I V and laminin antibodies, severe dysplasia and carcinoma exhibited dis continuous, thin and weakly stained basement membrane. The expression of fibronectin showed a direct correlation with extent of tumour progr ession. In normal mucosa, expression of fibronectin was almost absent, whereas in carcinoma intense expression of fibronectin was evident in the basment membrane and basal cells. These results emphasize the val ue of basement membrane proteins as biological markers for assessing o ral carcinogenesis.