Integrin receptors and their relationship to cellular proliferation and differentiation of oral squamous cell carcinoma. A quantitative immunohistochemical study.

The expression of extracellular matrix (ECM) proteins (fibronectin, laminin, collagen IV) and ECM receptors of integrin type (alpha 2 beta 1, collagen receptor; alpha 6 chain of the fibronectin receptor; alpha 6 chain of the laminin receptor) were examined in normal oral squamous epithelium and in invasive areas of squamous cell carcinomas with various differentiation and proliferation activities (Ki-67 antigen labelling), evaluating the presence, quantity (using an image analysis system) and distribution of the integrin subunits. In the mucosa, there was uniform immunostaining for alpha 2 beta 1 and alpha 6 concentrated at the cell membrane in the basal/supra basal cell zone, whereas, alpha 5 showed a discontinuous staining of the basal cell-basement membrane interface. alpha 2 and alpha 6 could be visualized in all carcinomas. alpha 5 showed low expression preferentially in less differentiated carcinomas. In contrast to normal mucosa, there was an increase in alpha 6 staining in well-differentiated carcinomas. Dedifferentiation of oral carcinomas was accompanied by an increase in cellular proliferation and with a decrease in alpha 2 beta 1 and alpha 6 staining. This reduction of alpha 6 staining was shown to be statistically significant, suggesting that this integrin may be a valuable grading parameter for oral squamous cell carcinoma.