Cancer and Metastasis: Importance of Cell Adhesion Molecules and Cell Junctions

Abstract

Metastasis is a complex process which is driven by several biochemical and molecular factors. Metastasis is a condition which severely limits cancer therapies and is responsible for 90% of cancer deaths. Therefore, it is of crucial importance to gain a greater understanding of the underlying mechanisms of metastasis in terms of developing treatment methods for metastasis prevention. Included in metastasis are multiple steps such as local invasion (epithelial-mesenchymal transition), intravasation, survival in the circulatory system, extravasation (transendothelial migration/diapedesis), formation of micrometastasis and metastatic colony. Tumor cells escape from circulating immune cells and apoptosis using platelets as a ‘‘shield’’ and a ‘‘link’’ for binding to endothelium via altering expression patterns of adhesion molecules. Extravasation in tumor cells is one of the key steps of metastasis and despite small differences in molecules, the whole process is basically the same in leukocytes; rolling, adhesion, and transmigration. Cell adhesion molecules such as integrins, and cell junctions such as Jam proteins, are key players in the extravasation step. Therefore, cell adhesion molecules and cell junctions can be used as potential targets for cancer therapy. In this review, the general processes of metastasis and the roles of cell adhesion molecules/cell junctions on metastasis were summarized.