High-Affinity <i>N</i>-(2-Hydroxypropyl)methacrylamide Copolymers with Tailored <i>N</i>-Acetyllactosamine Presentation Discriminate between Galectins
Marina Rodrigues Tavares, M Blahová, Lieselotte Sedláková, Lothar Elling, Helena Pelantová, Rafał Konefał, Tomáš Etrych, Vladimı́r Křen, Pavla Bojarová, Petr Chytil
Abstract
N-Acetyllactosamine (LacNAc; Galβ4GlcNAc) is a typical disaccharide ligand of galectins. The most abundant members of these human lectins, galectin-1 (Gal-1) and galectin-3 (Gal-3), participate in a number of pathologies including cancerogenesis and metastatic formation. In this study, we synthesized a series of fifteen N-(2-hydroxypropyl)methacrylamide (HPMA)-based glycopolymers with varying LacNAc amounts and presentations and evaluated the impact of their architecture on the binding affinity to Gal-1 and Gal-3. The controlled radical reversible addition–fragmentation chain transfer copolymerization technique afforded linear polymer precursors with comparable molecular weight (Mn ≈ 22,000 g mol–1) and narrow dispersity (D̵ ≈ 1.1). The precursors were conjugated with the functionalized LacNAc disaccharide (4–22 mol % content in glycopolymer) prepared by enzymatic synthesis under catalysis by β-galactosidase from Bacillus circulans. The structure–affinity relationship study based on the enzyme-linked immunosorbent assay revealed that the type of LacNAc presentation, individual or clustered on bi- or trivalent linkers, brings a clear discrimination (almost 300-fold) between Gal-1 and Gal-3, reaching avidity to Gal-1 in the nanomolar range. Whereas Gal-1 strongly preferred a dense presentation of individually distributed LacNAc epitopes, Gal-3 preferred a clustered LacNAc presentation. Such a strong galectin preference based just on the structure of a multivalent glycopolymer type is exceptional. The prepared nontoxic, nonimmunogenic, and biocompatible glycopolymers are prospective for therapeutic applications requiring selectivity for one particular galectin.