Regulation of cellular adhesion to extracellular matrix proteins by galectin-3

The control of cellular adhesion to extracellular matrix proteins is poorly understood. In the present analyses, we set out to test the hypothesis that high galectin-3 concentration on the cell surface downregulates cellular adhesion to the extracellular matrix proteins. Various tumor cell lines were briefly incubated without or with galectin-3 and then allowed to adhere to wells coated with laminin-1, collagen IV and fibronectin. Our data demonstrated that the cells which were incubated with galectin-3 prior to plating had significantly reduced adhesion to extracellular matrix proteins. This inhibition involved the carbohydrate recognition domain of the lectin because adhesion was achieved in the presence of galectin-3 and lactose but not galectin-3 and sucrose. Furthermore we demonstrated that galectin-3 associates with alpha 1 beta 1 integrin in a lactose dependent manner.