Galectin-3 promotes the adhesion, but not the migration of thyroid carcinoma cells in a β-galactoside-specific manner

Abstract

In thyroid carcinoma cells, the soluble β-galactoside- specific lectin, galectin-3, is extra- and intracellularly expressed and plays a significant role in thyroid cancer diagnosis. The functional relevance of this molecule, particularly in its extra- cellular environment however, warrants further elucidation. To gain insight into this topic, the present study characterized principal functional properties of galectin-3 in 3 commonly used thyroid carcinoma cell lines (B-CPAP, Cal-62 and FTC-133) that express the molecule intra- and extracellulary. Cell-intrinsic galectin-3 harbors a functional carbohydrate recognition domain as determined by affinity purification. Moreover, cell surface expressed galectin-3 can be partially removed by treatment with lactose or asialofetuin, but not with sucrose. Thyroid carcinoma cells adhere to substrate-bound galectin-3 in a β-galactoside-specific manner, whereby only cell adhesion, but not cell migration is promoted. Thus, thyroid tumor cells harbor functional active galectin-3 that, inter alia, specifically interacts with cell surface-expressed molecular ligands in a β-galactoside-dependent manner, whereby the molecule can at least interfere with cell adhesion. The modula- tion of galectin-3 expression level or its ligands in such tumor cells could be of therapeutic interest and needs further experi- mental clarification.