GALECTINS - VERSATILE MODULATORS OF CELL-ADHESION, CELL-PROLIFERATION, AND CELL-DEATH

Lectins, or carbohydrate binding proteins, recognize specific oligosac charide structures on glycoproteins and glycolipids. Several families of animal lectins have been identified; for some of these lectins, fun ctions such as leukocyte adhesion and microbial opsonization have been described. The galectins are a family of lectins found in species ran ging from sponges and nematodes to humans. Members of the galectin fam ily have been proposed to mediate cell adhesion, to regulate cell grow th, and to trigger or inhibit apoptosis. The expression pattern of dif ferent galectins changes during development, and this pattern is also altered at sites of inflammation and in breast, colon, prostate, and t hyroid carcinomas, In addition, the level of expression of some galect ins by tumor cells has been shown to be correlated with metastatic pot ential. The mechanisms by which galectins exert these diverse effects remain largely unknown. Some glycoprotein counterreceptors recognized by certain galectins have been identified; this is an important first step in understanding the cell-type specific effects of different gale ctins. This review discusses the way in which the modulation of galect in activity may affect strategies for treatment of a variety of human diseases, including autoimmunity and cancer.