CARBOHYDRATES AND SOLUBLE LECTINS IN THE REGULATION OF CELL-ADHESION AND PROLIFERATION

There is a large body of suggestions that complex carbohydrates play a role in the regulation of cell adhesion and cell proliferation. Many reports have emphasized that proteoglycans, glycoproteins or glycolipi ds are participating to cell adhesion mechanisms. The use of polyvalen t anti-carbohydrate antibodies and plant lectins as well as the use of glycosylation inhibitors suggested that cell proliferation can be mod ulated by surface carbohydrates. The dating experiment of Burger and N oonan (1970) showing restoration of contact inhibition of malignant ce lls by monovalent concanavalin A was a determining experiment. However , in the latter as in the others, no precise mechanism was demonstrate d how carbohydrates can be involved in adhesion and proliferation. New insights were opened with the discovery of vertrebrate membrane-bound and soluble lectins. The latter generally display agglutinating activ ities in in vitro systems, suggesting that they were potential cell ad hesion molecules, by forming bridges between cell surface carbohydrate s. These polyvalent molecules may be also considered as clustering age nts for their cell surface ligands, consequently generating signals fo r cell proliferation and/or differentiation.