Abstract 342: Breast cancer adhesion cascade is influenced by Galectin-1 and E-selectin receptor-ligand interactions
Authors: Reynolds Nathan M. , Hall Claire R. , Thomas Sean E. , Burdick Monica M. 
Published: August 2015

Abstract
Invasion of other tissues during bloodborne metastasis requires the adhesion of cancer cells to the endothelium by specific fluid shear-dependent receptor-ligand interactions. It is hypothesized that ligands are shared between the endothelial adhesion molecule known as E-selectin, a transmembrane glycoprotein, and Galectin-1 (Gal-1), a secretory dimer protein, both of which are upregulated during inflammation and cancer. Our previous data strongly indicate that this shear-dependent interaction involves the same or closely related cancer cell-expressed ligands, such as the glycoprotein Mac-2BP. Initial investigation using immuno-staining methods to locate E-selectin and Gal-1 ligands and determine relative proximity to one another revealed that E-selectin and Gal-1 ligands on ZR-75-1 breast cancer cells and breast cancer tissue microarrays had a high percentage of colocalization, as high as 75% in some cases. These results allude to the possibility that these reactive molecules are in close proximity or are in fact the same molecule. Subsequently, E-selectin microspheres were perfused over Gal-1-treated ZR-75-1 cell monolayers and breast cancer tissue microarrays to determine the functional relationship, if any, between Gal-1 and E-selectin ligands during adhesion from flow. Flow assay data show that Gal-1 treatment enhances E-selectin microsphere interactions to a breast cancer monolayer in a shear-dependent manner, with a shear stress of 0.5 dynes/cm2 having an almost 300% increase in binding compared to the untreated monolayer. This amount of binding at a physiological shear stress gives credence to the hypothesis that Gal-1 influences E-selectin receptor-ligand interactions via the same or similar ligands during breast cancer cell adhesion. Dynamic biochemical tissue analysis (DBTA), a novel flow-based tissue interrogation technique developed in our lab, was then implemented to test human invasive ductal breast carcinoma tissue sections. Similar to ZR-75-1 cell line flow assay data, a 142% increase in shear-dependent binding interactions between the E-selectin microspheres and the Gal-1 treated breast cancer tissue sections at 0.5 dynes/cm2 shear stress was observed. Colocalization of reactive signals and increased shear-dependent flow interactions indicate that metastatic binding in breast cancer is aided through E-selectin to Gal-1 interaction via a shared ligand intermediate. Ascertaining the mechanism behind this interaction would lead to a better understanding of the circulating breast cancer cells’ adhesion cascade during metastasis.
Citation Format: Nathan M. Reynolds, Claire R. Hall, Sean E. Thomas, Monica M. Burdick. Breast cancer adhesion cascade is influenced by Galectin-1 and E-selectin receptor-ligand interactions. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 342. doi:10.1158/1538-7445.AM2015-342