Abstract 204: Breast cancer stem and non-stem-like cells express varying levels of selectin ligand activities

Cancer stem cells are a subset of tumor cells proposed to possess traits enabling metastatic invasion. Independently, selectins and their ligands are believed to play major roles in mediating the adhesion of circulating tumor cells to vascular endothelium during hematogenous metastasis. We thus hypothesized that the expression level of selectin ligands on breast cancer cells is related to breast cancer stem cell (BSC) or non-BSC phenotypes. Five breast carcinoma cell lines analyzed by flow cytometry were categorized as BSCs by the surface expression profile CD44+/CD24-/low, or non-BSCs marked by alternative expression of these proteins. All cell lines positively expressed E-, P-, and L-selectin ligand activity by flow cytometric analysis as well as under physiological flow conditions. Consistent with their E-selectin ligand activities, all cell lines expressed putative glycans for E-selectin binding, including sLeX, sLeA, and/or VIM-2 glycans, found by flow cytometric analysis. Yet the level of selectin ligand activity and glycan expression in BSCs was conspicuously lower than in non-BSCs. The abundant production of selectin-reactive glycans in non-BSCs was associated with α-(1,3)- and α-(1,4)-fucosyltransferases, as indicated by qRT-PCR analysis. Importantly, BSCs as well as non-BSCs expressed molecules, such as CD44, that are capable of carrying carbohydrates necessary for E-selectin ligand function. Furthermore, BSCs were mesenchymal-like and non-BSCs were epithelial-like cells, as found by immunostaining of breast cancer cells for E-cadherin and N-cadherin in fluorescence microscopy. Significantly, treatment of a non-BSC cell line with TGF-β induced epithelial-to-mesenchymal transition (EMT) marked by changes in cell morphology, increases in expression levels of N-cadherin, and increases in E-cadherin suppressor genes. These EMT cells showed reduced levels of E-selectin ligand activity under physiological flow conditions, indicating loss of selectin ligand activity upon acquisition of mesenchymal properties. In summary, the selectin ligand activity of BSCs is lower than that of non-BSCs, and the level of selectin ligand activity of breast cancer cells is potentially controlled by BSC and EMT states. Citation Format: Venktesh S. Shirure, Chengkai Xiong, Fabian Benencia, Monica M. Burdick. Breast cancer stem and non-stem-like cells express varying levels of selectin ligand activities. [abstract]. In: Proceedings of the 104th Annual Meeting of the America