TF-containing MUC1 glycopeptides fail to entice Galectin-1 recognition of tumor-associated Thomsen-Freidenreich (TF) antigen (CD176) in solution.
Aberrant Mucin-1 (MUC1) glycosylation with the Thomsen-Friedenreich (TF) tumor-associated antigen (CD176) is a hallmark of epithelial carcinoma progression and poor patient prognosis. Recognition of TF by glycan-binding proteins, such as galectins, enables the pathological repercussions of this glycan presentation, yet the underlying binding specificities of different members of the galectin family is a matter of continual investigation. While Galectin-3 (Gal-3) recognition of TF has been well-documented at both the cellular and molecular level, Galectin-1 (Gal-1) recognition of TF has only truly been alluded to in cell-based platforms. Immunohistochemical analyses have purported Gal-1 binding to TF on MUC1 at the cell surface, however binding at the molecular level was inconclusive. We hypothesize that glycan scaffold (MUC1's tandem repeat peptide sequence) and/or multivalency play a role in the binding recognition of TF antigen by Gal-1. In this study we have developed a method for large-scale expression of Gal-1 and its histidine-tagged analog for use in binding studies by isothermal titration calorimetry (ITC) and development of an analytical method based on AlphaScreen technology to screen for Gal-1 inhibitors. Surprisingly, neither glycan scaffold or multivalent presentation of TF antigen on the scaffold was able to entice Gal-1 recognition to the level of affinity expected for functional significance. Future evaluations of the Gal-1/TF binding interaction in order to draw connections between immunohistochemical data and analytical measurements are warranted.
['FitzGerald|Forrest G|FG|', 'Rodriguez Benavente|Maria C|MC|', 'Garcia|Camelia|C|', 'Rivero|Yaima|Y|', 'Singh|YashoNandini|Y|', 'Wang|Hongjie|H|', 'Fields|Gregg B|GB|', 'Cudic|Maré|M|0000-0002-7657-0400']
D015295:Antigens, Tumor-Associated, Carbohydrate D001798:Blood Proteins D037483:Galectin 1 D037161:Galectins D006020:Glycopeptides D006801:Humans D018396:Mucin-1 D011485:Protein Binding
Galectin-1 Mucin-1 TF antigen Isothermal titration Calorimetry (ITC) Carbohydrate recognition