Glycobiology Insights

Galectins are a family of proteins that contain a canonical carbohydrate-recognition domain (CRD) with affinity for beta-galactosides. Within this family, an unique member, the chimeric, galectin-3, may be found in the cytoplasm and nucleus, and on the cell surface, besides being released into the extracellular space. Galectin-3 interactions with certain glycans and extracellular matrix (ECM) proteins have been described to promote and/or antagonize tumor cell apoptosis, to induce endothelial cell proliferation and angiogenesis, and to promote tumor cell adhesion and invasion, thus both potentially facilitating and hindering metastasis. Moreover, although galectin-3 is expressed in several types of malignancies and its expression has been correlated with transformation and metastasis-related events, its downregulation has also been associated with malignancy and tumor progression. These apparently conflicting data demonstrate that the role of galectin-3 in metastasis remains to be fully understood. Of course in nature, different cancer progression phenomena are simultaneously occurring in the many instances, where the patient has primary tumor and blood-borne and distant metastatic cells. This makes it all the more interesting to overview the role of galectins in cancer metastasis, especially galectin-3, since these and their related molecules are more than probable disease marker candidates and/or therapeutic targets.