title: Peptides specific to the galectin-3 carbohydrate recognition domain inhibit metastasis-associated cancer cell adhesion.
abstract: Intravascular cancer cell adhesion plays a significant role in the metastatic process. Studies indicate that galectin-3, a member of the galectin family of soluble animal lectins, is involved in carbohydrate-mediated metastatic cell heterotypic (between carcinoma cells and endothelium) and homotypic (between carcinoma cells) adhesion via interactions with the tumor-specific Thomsen-Friedenreich glycoantigen (TFAg). We hypothesized that blocking the galectin-3 carbohydrate recognition domain with synthetic peptides would significantly reduce metastasis-associated carcinoma cell adhesion. To test this hypothesis, we identified peptide antagonists of the galectin-3 carbohydrate recognition domain using combinatorial bacteriophage display technology. The peptides bound with high affinity to purified recombinant galectin-3 protein (K(d) approximately 17-80 nM) and to cell surface galectin-3. Experiments with a series of recombinant serially truncated galectin-3 mutants indicated that the peptides bound the carbohydrate recognition domain of galectin-3. Furthermore, the peptides did not bind the carbohydrate recognition domain of other galectins and plant lectins. Synthetic galectin-3 carbohydrate recognition domain-specific peptides blocked the interaction between galectin-3 and TFAg and significantly inhibited rolling and stable heterotypic adhesion of human MDA-MB-435 breast carcinoma cells to endothelial cells under flow conditions, as well as homotypic tumor cell aggregation. These results demonstrate that carbohydrate-mediated, metastasis-associated tumor cell adhesion could be inhibited efficiently with short synthetic peptides which do not mimic naturally occurring glycoepitopes yet bind to the galectin-3 carbohydrate recognition domain with high affinity and specificity.
authors.affiliation: Department of Biochemistry, University of Missouri, Columbia, MO 65212, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Zou
authors.forename: Vladislav V
authors.initials: VV
authors.lastname: Glinsky
authors.forename: Linda A
authors.initials: LA
authors.lastname: Landon
authors.forename: Leslie
authors.initials: L
authors.lastname: Matthews
authors.forename: Susan L
authors.initials: SL
authors.lastname: Deutscher
mesh_terms: D015295:Antigens, Tumor-Associated, Carbohydrate / Q000378:metabolism*; D001435:Bacteriophages / Q000235:genetics; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D042783:Endothelial Cells; D037502:Galectin 3 / Q000378:metabolism*; D006801:Humans; D009154:Mutation / Q000235:genetics; D009362:Neoplasm Metastasis / Q000473:pathology*; D019151:Peptide Library; D010455:Peptides / Q000494:pharmacology*
chemical_list: D015295:Antigens, Tumor-Associated, Carbohydrate; D037502:Galectin 3; D019151:Peptide Library; D010455:Peptides; C016467:Thomsen-Friedenreich antigen