Galectins are small human proteins participating in inflammation processes, immune response, and cancerogenesis. Tandem-repeat galectins comprising Gal-4, Gal-8, and Gal-9 are a vital yet less studied part of the galectin fingerprint in cancer-related processes. The present work studies a library of prepared multivalent neo-glycoproteins decorated with poly-N-acetyllactosamine and human-milk-type oligosaccharides as ligands of this underexplored family of tandem-repeat galectins. A thorough binding evaluation by ELISA and biolayer interferometry was complemented with a detailed epitope mapping both from the galectin and the glycoconjugate viewpoints by nuclear magnetic resonance. The found interactions in the galectin binding site were correlated to in silico data from molecular modeling. The present work reveals pioneer information on the binding of tandem-repeat galectins to multivalent glycoconjugates carrying complex carbohydrate ligands and represents an invaluable starting point for the development of new high-affinity tailored ligands of tandem-repeat galectins, needed both for diagnosis and therapy.

• MeSH
• Galectins * chemistry   metabolism   MeSH
• Glycoproteins * chemistry   metabolism   MeSH
• Humans MeSH
• Ligands MeSH
• Milk, Human * chemistry   MeSH
• Oligosaccharides * chemistry   metabolism   MeSH
• Polysaccharides MeSH
• Tandem Repeat Sequences MeSH
• Binding Sites MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Galectins * MeSH
• Glycoproteins * MeSH
• Ligands MeSH
• Oligosaccharides * MeSH
• poly-N-acetyllactosamine MeSH Browser
• Polysaccharides MeSH

INTRODUCTION: The immunosuppressive roles of galectin-3 (Gal-3) in carcinogenesis make this lectin an attractive target for pharmacological inhibition in immunotherapy. Although current clinical immunotherapies appear promising in the treatment of solid tumors, their efficacy is significantly weakened by the hostile immunosuppressive tumor microenvironment (TME). Gal-3, a prominent TME modulator, efficiently subverts the elimination of cancer, either directly by inducing apoptosis of immune cells or indirectly by binding essential effector molecules, such as interferon-gamma (IFNγ). METHODS: N-(2-Hydroxypropyl)methacrylamide (HPMA)-based glycopolymers bearing poly-N-acetyllactosamine-derived tetrasaccharide ligands of Gal-3 were designed, synthesized, and characterized using high-performance liquid chromatography, dynamic light scattering, UV-Vis spectrophotometry, gel permeation chromatography, nuclear magnetic resonance, high-resolution mass spectrometry and CCK-8 assay for evaluation of glycopolymer non-toxicity. Pro-immunogenic effects of purified glycopolymers were tested by apoptotic assay using flow cytometry, competitive ELISA, and in vitro cell-free INFγ-based assay. RESULTS: All tested glycopolymers completely inhibited Gal-3-induced apoptosis of monocytes/macrophages, of which the M1 subtype is responsible for eliminating cancer cells during immunotherapy. Moreover, the glycopolymers suppressed Gal-3-induced capture of glycosylated IFNγ by competitive inhibition to Gal-3 carbohydrate recognition domain (CRD), which enables further inherent biological activities of this effector, such as differentiation of monocytes into M1 macrophages and repolarization of M2-macrophages to the M1 state. CONCLUSION: The prepared glycopolymers are promising inhibitors of Gal-3 and may serve as important supportive anti-cancer nanosystems enabling the infiltration of proinflammatory macrophages and the reprogramming of unwanted M2 macrophages into the M1 subtype.

• Keywords
• carbohydrate, galectin-3, glycopolymer, interferon-gamma, monocyte, tumor microenvironment,
• MeSH
• Acrylamides chemistry   pharmacology   MeSH
• Apoptosis drug effects   MeSH
• Galectin 3 * antagonists & inhibitors   MeSH
• Galectins MeSH
• Interferon-gamma * metabolism   MeSH
• Blood Proteins MeSH
• Humans MeSH
• Macrophages drug effects   MeSH
• Monocytes * drug effects   MeSH
• Tumor Microenvironment drug effects   MeSH
• Polymers * chemistry   pharmacology   MeSH
• Antineoplastic Agents * pharmacology   chemistry   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Acrylamides MeSH
• Galectin 3 * MeSH
• Galectins MeSH
• Interferon-gamma * MeSH
• Blood Proteins MeSH
• LGALS3 protein, human MeSH Browser
• Polymers * MeSH
• Antineoplastic Agents * MeSH

Pulmonary hypertension is a cardiovascular disease with a low survival rate. The protein galectin-3 (Gal-3) binding β-galactosides of cellular glycoproteins plays an important role in the onset and development of this disease. Carbohydrate-based drugs that target Gal-3 represent a new therapeutic strategy in the treatment of pulmonary hypertension. Here, we present the synthesis of novel hydrophilic glycopolymer inhibitors of Gal-3 based on a polyoxazoline chain decorated with carbohydrate ligands. Biolayer interferometry revealed a high binding affinity of these glycopolymers to Gal-3 in the subnanomolar range. In the cell cultures of cardiac fibroblasts and pulmonary artery smooth muscle cells, the most potent glycopolymer 18 (Lac-high) caused a decrease in the expression of markers of tissue remodeling in pulmonary hypertension. The glycopolymers were shown to penetrate into the cells. In a biodistribution and pharmacokinetics study in rats, the glycopolymers accumulated in heart and lung tissues, which are most affected by pulmonary hypertension.

• MeSH
• Pulmonary Artery drug effects   metabolism   MeSH
• Biomarkers MeSH
• Fibroblasts drug effects   metabolism   MeSH
• Galectin 3 * antagonists & inhibitors   metabolism   MeSH
• Rats MeSH
• Cells, Cultured MeSH
• Humans MeSH
• Hypertension, Pulmonary * drug therapy   metabolism   MeSH
• Polymers chemistry   pharmacology   MeSH
• Tissue Distribution MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Humans MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Biomarkers MeSH
• Galectin 3 * MeSH
• Polymers MeSH

Galectins, the glycan binding proteins, and their respective carbohydrate ligands represent a unique fundamental regulatory network modulating a plethora of biological processes. The advances in galectin-targeted therapy must be based on a deep understanding of the mechanism of ligand-protein recognition. Carbosilane dendrimers, the well-defined and finely tunable nanoscaffolds with low toxicity, are promising for multivalent carbohydrate ligand presentation to target galectin receptors. The study discloses a synthetic method for two types of lactose-functionalized carbosilane glycodendrimers (Lac-CS-DDMs). Furthermore, we report their outstanding, dendritic effect-driven affinity to tandem-type galectins, especially Gal-9. In the enzyme-linked immunosorbent assay, the affinity of the third-generation multivalent dendritic ligand bearing 32 lactose units to Gal-9 reached nanomolar values (IC50 = 970 nM), being a 1400-fold more effective inhibitor than monovalent lactose for this protein. This demonstrates a game-changing impact of multivalent presentation on the inhibitory effect of a ligand as simple as lactose. Moreover, using DLS hydrodynamic diameter measurements, we correlated the increased affinity of the glycodendrimer ligands to Gal-3 and Gal-8 but especially to Gal-9 with the formation of relatively uniform and stable galectin/Lac-CS-DDM aggregates.

• MeSH
• Galectins * metabolism   MeSH
• Lactose * MeSH
• Ligands MeSH
• Polysaccharides MeSH
• Protein Binding MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• carbosilane MeSH Browser
• Galectins * MeSH
• Lactose * MeSH
• Ligands MeSH
• Polysaccharides MeSH

Galectins are carbohydrate-binding lectins that modulate the proliferation, apoptosis, adhesion, or migration of cells by cross-linking glycans on cell membranes or extracellular matrix components. Galectin-4 (Gal-4) is a tandem-repeat-type galectin expressed mainly in the epithelial cells of the gastrointestinal tract. It consists of an N- and a C-terminal carbohydrate-binding domain (CRD), each with distinct binding affinities, interconnected with a peptide linker. Compared to other more abundant galectins, the knowledge of the pathophysiology of Gal-4 is sparse. Its altered expression in tumor tissue is associated with, for example, colon, colorectal, and liver cancers, and it increases in tumor progression, and metastasis. There is also very limited information on the preferences of Gal-4 for its carbohydrate ligands, particularly with respect to Gal-4 subunits. Similarly, there is virtually no information on the interaction of Gal-4 with multivalent ligands. This work shows the expression and purification of Gal-4 and its subunits and presents a structure-affinity relationship study with a library of oligosaccharide ligands. Furthermore, the influence of multivalency is demonstrated in the interaction with a model lactosyl-decorated synthetic glycoconjugate. The present data may be used in biomedical research for the design of efficient ligands of Gal-4 with diagnostic or therapeutic potential.

• Keywords
• blood-group antigen, galectin-4, inhibitor, multivalency, oligosaccharide, transglycosylation,
• MeSH
• Galectin 4 * MeSH
• Galectins chemistry   MeSH
• Humans MeSH
• Ligands MeSH
• Neoplasms * MeSH
• Oligosaccharides chemistry   MeSH
• Carbohydrates MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Galectin 4 * MeSH
• Galectins MeSH
• Ligands MeSH
• Oligosaccharides MeSH
• Carbohydrates MeSH