Systematic Tuning of Fluoro-galectin-3 Interactions Provides Thiodigalactoside Derivatives with Single-Digit nM Affinity and High Selectivity.

Symmetrical and asymmetrical fluorinated phenyltriazolyl-thiodigalactoside derivatives have been synthesized and evaluated as inhibitors of galectin-1 and galectin-3. Systematic tuning of the phenyltriazolyl-thiodigalactosides' fluoro-interactions with galectin-3 led to the discovery of inhibitors with exceptional affinities (K down to 1-2 nM) in symmetrically substituted thiodigalactosides as well as unsurpassed combination of high affinity (K 7.5 nM) and selectivity (46-fold) over galectin-1 for asymmetrical thiodigalactosides by carrying one trifluorphenyltriazole and one coumaryl moiety.

Galectin-3-Binding Glycomimetics that Strongly Reduce Bleomycin-Induced Lung Fibrosis and Modulate Intracellular Glycan Recognition.

Discovery of glycan-competitive galectin-3-binding compounds that attenuate lung fibrosis in a murine model and that block intracellular galectin-3 accumulation at damaged vesicles, hence revealing galectin-3-glycan interactions involved in fibrosis progression and in intracellular galectin-3 activities, is reported. 3,3'-Bis-(4-aryltriazol-1-yl)thiodigalactosides were synthesized and evaluated as antagonists of galectin-1, -2, -3, and -4 N-terminal, -4 C-terminal, -7 and -8 N-terminal, -9 N-terminal, and -9 C-terminal domains. Compounds displaying low-nanomolar affinities for galectins-1 and -3 were identified in a competitive fluorescence anisotropy assay.

Synthesis of a 3'-naphthamido-LacNAc fluorescein conjugate with high selectivity and affinity for galectin-3.

Described is the synthesis of a fluorescent LacNAc derivative appended with a 3'-deoxy-3'-naphthamido functionality, 2-(fluorescein-5/6-amido)ethyl 3-deoxy-3-(2-naphthamido)-beta-D-galactopyranosyl-(1-->4)-2-acetamido-2-deoxy-beta-D-glucopyranoside, which confers high affinity (Kd 170 nM) and selectivity for galectin-3 via a stacking interaction with Arg144. Its use as a selective and sensitive galectin-3 probe is demonstrated with fluorescence polarization measurements.

Structural and thermodynamic studies on cation-Pi interactions in lectin-ligand complexes: high-affinity galectin-3 inhibitors through fine-tuning of an arginine-arene interaction.

The high-resolution X-ray crystal structures of the carbohydrate recognition domain of human galectin-3 were solved in complex with N-acetyllactosamine (LacNAc) and the high-affinity inhibitor, methyl 2-acetamido-2-deoxy-4-O-(3-deoxy-3-[4-methoxy-2,3,5,6-tetrafluorobenzamido]-beta-D-galactopyranose)-beta-D-glucopyranoside, to gain insight into the basis for the affinity-enhancing effect of the 4-methoxy-2,3,5,6-tetrafluorobenzamido moiety. The structures show that the side chain of Arg144 stacks against the aromatic moiety of the inhibitor, an interaction made possible by a reorientation of the side chain relative to that seen in the LacNAc complex. Based on these structures, synthesis of second generation LacNAc derivatives carrying aromatic amides at 3'-C, followed by screening with a novel fluorescence polarization assay, has led to the identification of inhibitors with further enhanced affinity for galectin-3 (K(d) > or = 320 nM).

Fluorescence polarization as an analytical tool to evaluate galectin-ligand interactions.

Galectins are a family of beta-galactose binding lectins associated with functions such as immunological and malignant events. To study the binding affinity of galectins for natural and artificial saccharides and glycoconjugates we have developed an assay using fluorescence polarization. A collection of fluorescein-conjugated saccharides was synthesized and used as probes with galectins-1 and -3 and the two carbohydrate recognition domains of galectin-4.

Truncated galectin-3 inhibits tumor growth and metastasis in orthotopic nude mouse model of human breast cancer.

Purpose: The goal of this research was to evaluate a potential therapeutic agent for breast cancer based on galectin-3 that has been implicated in tumorigenicity and metastasis of breast cancer. The hypothesis was that therapy with NH(2)-terminally truncated form of galectin-3 (galectin-3C) will be efficacious for reduction in tumor growth and for inhibition of metastases.

Experimental Design: Recombinant human galectin-3 was produced in Escherichia coli from which galectin-3C was derived by collagenase enzyme digestion.