Adhesion molecules and their implication in the immune response to oral cancer

    Abstract

    Tumor development is dependent upon a series of factors, many of which remain unknown and therefore unpredictable. In many cases tumor evolution follows an unexpected course; the habitual clinical and histopathological predictive parameters are therefore of little use in such situations. The prediction of tumor evolution clearly implies multiple factors. In this context, the analysis of the host immune response is fundamental for evaluating tumor behavior. Adhesion molecules are essential for immune cell recognition of and adhesion to neoplastic cells - these being aspects that are in turn vital for the initiation and amplification of the host antitumor response. Based on structural criteria, the adhesion molecules are divided into four main groups: integrins, selectins, immunoglobulins and other adhesion molecules. Effective immune response requires binding of the integrins LFA-1 (lymphocyte function antigen 1) expressed by T cells, and Mac-1 expressed by phagocytes, to their natural ligand (intercellular adhesion molecule 1, or ICAM-1) expressed by tumor cells of the oral cavity. The expression of selectin E by oral neoplastic tissue in turn facilitates infiltration of the tumor by macrophages and other inflammatory cells. Furthermore, increased ICAM-1 expression enhances binding stability between tumor cells and the host cytotoxic cells - thereby incrementing the destructive effect of the latter. Other adhesion molecules have also been related to oral tumors, including the v6 variant of CD44, for which negative expression has been found to be more frequent in poorly differentiated carcinomas. The present study reviews the role of certain adhesion molecules in the initiation and development of the host antitumor response to oral squamous cell carcinoma.