Adhesive receptors expressed by tumor cells and platelets: novel targets for therapeutic anti-metastatic strategies.

In vitro and in vivo studies have demonstrated that adhesive interactions between tumor cells and platelets may play a central role in the metastatic process. Ultrastructural studies have demonstrated that platelets appear to enhance the development of arrested tumor emboli into a secondary metastatic colony. Platelet adhesive glycoprotein receptors and their immunorelated counterparts expressed by tumor cells participate in tumor-induced platelet aggregation, which may be an early step in the development of a metastatic lesion. Platelet anti-adhesive agents have been demonstrated to reduce metastases in rodent models. Although tumor adhesive glycoproteins have yet to be fully characterized, specific inhibition of their functional sites could constitute a forthcoming strategy for effective inhibition of metastases.