Tumor progression: the role of cadherins and integrins.

Established cadherin and integrin-containing adherens junctions maintain the integrity of normal tissues. Signalling via adhesion-molecule systems is an important factor in the control of cellular growth and differentiation. In transformed cells, destructive changes in the adhesion systems lead to abnormal relationships among neighbouring cells and the extracellular matrix. Adhesion molecules may prevent tumour progression by firmly attaching cells to each other, and by anchoring them in the extracellular matrix. In addition, cadherins and integrins may have a direct role in tumour suppression by participating in growth control. Dissemination of cancer cells, i.e. invasion and metastasis, requires movement of cells, as well as adhesion to extracellular matrices and to other cells. Particular integrins have been implicated in several aspects of this multistep process. In this article, the data on the possible roles of cadherins and integrins in tumor progression are summarized.