Integrins and skin tumours

It is well know that cell-cell and cell-matrix interactions play an important role in maintaining the integrity of pluristratified epithelia and in different biological processes such as wound healing, inflammation, and immune response. In addition, growing evidence indicates that these interactions are also fundamental in tumour cell growth and invasion. Important advances in the understanding the mechanism of cell adhesion has been possible owing the identification and characterization of a large number of specific cell adhesion molecules. Integrins are a family of transmembrane adhesion receptors that mediate cell adhesion to extracellular matrix protein and to the surface of other cells. In this review the structure and the function of these adhesion receptors are summarized, and their possible involvement in skin tumours is discussed. The peculiar distribution pattern of some members of the integrin famil (α6β4, α5β1, and α10.1.2 integrins) found in neoplastic cells of squamous cell carcinoma (SCC), may reflect the different biological behavior of this tumour as compared to basal cell carcinoma (BCC). Therefore immunohistochemical study of integrins expression may be used for the phenotypic classification of tumours and as indicator of invasiveness. Finally, increasing evidence indicates that integrins are able to transmit signals from the extracellular matrix to the cell interior, that control gene expression, the cell cycle, and tumour growth. Thus, the role of integrins in cancer seems not only to involve cell adhesion events, but may also involve the regulation of cell growth and differentiation.