Presence of Cytoadhesins (IIb-IIIa-like glycoproteins) on Human Metastatic Melanomas but not on Benign Melanocytes

Glycoproteins IIb and IIIa, a heterodimer complex, play a vital role in blood platelet aggregation and are members of a wide family of membrane receptors known as integrins or cytoadhesins. Cellular interaction to extracellular matrix (ECM) adhesive proteins is mediated by integrins. Certain tumor cells are known to interact with ECM and blood platelets in the process of metastasis. However, it is not known if tumor cells, compared with their normal counterparts, acquire IIb-IIIa-like receptors to help them in their metastatic spread. In this study, monoclonal antibodies directed against the IIb-IIIa platelet glycoprotein complex were used on frozen biopsies of normal and various tumor tissues to detect the presence of these integrins. These studies demonstrate the presence of IIb-IIIa-like glycoproteins on the cells of metastatic malignant melanoma but not on benign melanocytes and rarely on other tumors. The presence of integrins on melanomas may help explain their propensity for frequent metastasis.