DISTRIBUTION OF BETA-1,ALPHA-1,ALPHA-2 AND ALPHA-3 INTEGRIN CHAINS IN BASAL-CELL CARCINOMAS

The integrins are alpha-beta heterodimeric transmembrane proteins mediating cell-substratum as well as cell-cell interactions. Changes in their expression and/or function seem to occur in a number of malignant epithelial neoplasms and may in part explain their abnormal patterns of growth and differentiation. Using monoclonal antibodies to the beta-1 (DH12), alpha-1 (TS2/7), alpha-2 (B1.515), and alpha-3 (E1.56) integrin chains, the alpha-1-beta-1 (VLA-1), alpha-2-beta-1 (VLA-2), alpha-3-beta-1 (VLA-3) integrin receptors were studied on cryostat sections of 22 basal cell carcinomas (BCCs) and adjacent normal tissues by a standard peroxidase-antiperoxidase technique. In non-neoplastic skin, VLA-2 and VLA-3 were found in the basal layer, eccrine glands, and cells of the outer root sheath in which VLA-1 was detected. In BCCs, there was a considerably higher expression of VLA-2 and VLA-3 compared with epidermal basal cells but similar to that seen in hair bulb and outer root sheath. In two cases of nodular BCC showing evidence of regression, both VLA-2 and VLA-3 were completely negative, in contrast to non-regressing foci which were strongly positive. The high level of expression of two adhesion molecules (VLA-2 and VLA-3) involved in cell-substratum as well as cell-cell interaction may account for the more indolent pattern of growth characteristic of BCC and perhaps reflect its high degree of differentiation towards the hair follicle.