Can alterations in integrin and laminin-5 expression be used as markers of malignancy?

Development of squamous cell carcinomas (SCCs) involves alterations in the adhesive interactions in the epithelium and invasion through the basement membrane. Therefore, changes in the expression of receptors and ligands involved in cell-cell and cell-matrix adhesion may be essential for the transformation of a premalignant into a malignant lesion, The aim of this study was to examine if expression of specific cell adhesion molecules can be used as markers of malignant development. By immunohistochemistry, we examined the expression pattern of integrins alpha 2 beta 1, alpha 3 beta 1, alpha 6 beta 4 and laminin-5 in biopsies from SCCs (n=18), premalignant lesions (leukoplakias, n=21) and non-premalignant tissue with chronic inflammation (n=11). In poorly differentiated SCCs, patchy loss of alpha 3 beta 1, alpha 6 beta 4 and laminin-5 expression was pronounced at the invasion front, whereas there was a tendency to increased expression of alpha 2 beta 1. Analogous to the SCCs, biopsies from the leukoplakias and the non-premalignant inflammatory tissue showed alterations of the expression of alpha 3 beta 1 and alpha 6 beta 4 in the basal cell layers and of laminin-5. However, a characteristic finding in biopsies from leukoplakias was loss of alpha 2 beta 1 and alpha 3 beta 1 in the suprabasal cells. There was no unequivocal expression of the adhesion molecules distinguishing between inflammatory tissue, premalignant, and malignant lesions.