The effect of galectin 1 on 3T3 cell proliferation on chitosan membranes.

Galectin-1 (GAL1), a beta-galactoside-binding protein, functions in cell adhesion, development, and growth regulation. A number of studies suggest that GAL1 play an important role in enhancing cell adhesion to extracellular matrix and inducing cell proliferation. Chitosan is a derivative of chitin extracted from lobsters, crabs and shrimps' exoskeletons. In clinical medicine, chitosan membrane had been used as a semi-permeable biological dressing. Although chitosan membranes show no cytotoxicity, some cell types (e.g. 3T3 cells) fail to attach and proliferate on their surface. In these studies, we show that over-expression of GAL1 does not enhance 3T3 cell proliferation on chitosan membranes. However, coating the chitosan membrane with recombinant GAL1 proteins significantly expedites 3T3 cells proliferation. The enhanced cell growth was inhibited by thiodigalactoside (TDG, a potent inhibitor of beta-galactoside binding) and GAL1 monoclonal antibodies, suggesting GAL1's specific effect on the proliferation of 3T3 cells upon chitosan membranes. Moreover, immunoblotting detected a markedly suppressed tyrosine phosphorylation in several proteins on 3T3 cell growths upon GAL1-coated chitosan membrane. Pretreating the cells with sodium fluoride (NaF, a phosphatase inhibitor) inhibits the attachment and proliferation of 3T3 cells. These findings support a proposed role for altered levels of protein phosphorylation in GAL1-mediated cell attachment and proliferation on chitosan membranes.