Interaction with the heparin-derived binding inhibitors destabilizes galectin-3 protein structure

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• Galectin-3 is a protein implicated in cancer development, progression, and metastasis.
• Inhibiting galectin-3 is a potential therapeutic strategy for cancer treatment.
• Previous research identified heparin-derived compounds as galectin-3 inhibitors without anticoagulant activity.

Purpose of the Study:

• To determine the binding affinities of novel heparin-derived galectin-3 inhibitors.
• To investigate the molecular mechanism of interaction between these inhibitors and galectin-3.
• To provide insights into the anti-cancer effects of these compounds.

Main Methods:

• Isothermal titration calorimetry (ITC) ligand displacement assay to measure binding affinities.
• Differential scanning fluorimetry (DSF) to assess protein stability and binding interactions.
• Utilizing specific heparin-derived ligands (compounds E, F, E3, F3) and N-acetyl-lactosamine as a control.

Main Results:

• Heparin-derived ligands (E, F, E3, F3) bind to galectin-3 with dissociation constants (K_D) between 0.96 and 1.32 mM.
• Unlike N-acetyl-lactosamine, which stabilizes galectin-3, these ligands bind to the unfolded form of galectin-3, causing protein destabilization.
• These findings correlate with previously observed inhibition of cancer cell adhesion, invasion, angiogenesis, and metastasis.

Conclusions:

• The identified heparin-derived compounds are effective binders of galectin-3.
• Their mechanism involves destabilizing the galectin-3 protein structure, distinct from stabilizing ligands.
• These molecular insights support the therapeutic potential of these heparin derivatives in cancer treatment.