Abstract 1609: The epithelial to mesenchymal transition regulates the expression of E-selectin ligands on breast cancer cell lines

Abstract

Abstract Breast cancer cells garner invasive and stem-like characteristics through the epithelial to mesenchymal transition (EMT). Consequently, the EMT has been implicated in cancer metastasis. While many of the effects of the EMT have been elucidated, it is currently unknown how the EMT modifies the expression of E-selectin ligands on breast cancer cells. These ligands are often sialofucosylated glycans that mediate cell adhesion with E-selectin molecules presented by endothelial cells lining the blood vessel walls at the metastatic site, which is commonly bone marrow. Although E-selectin is widely recognized for its role in promoting adhesion during tumor cell extravasation, it also maintains the quiescence of hematopoietic stem cells in the vascular niche of the bone marrow. Thus in this investigation, we studied the effects of the EMT on the E-selectin ligand activities of breast cancer cell lines and their behavior in an E-selectin rich environment. The EMT was induced in breast cancer cell lines by ectopic expression of either the Snail or Twist transcription factors. Through the EMT breast cancer cells upregulated the expression of vimentin and N-cadherin, yet reduced the expression of CD24, E-cadherin, and E-selectin ligands. Breast cancer cell lines were assayed for E-selectin ligand activity using laminar flow assays, flow cytometry, qPCR, and were cultured on E-selectin-coated tissue culture plates. In laminar flow assays breast cancer cells were perfused over E-selectin substrates using physiological flow conditions. Breast cancer cells expressing Snail or Twist adhered to E-selectin from the free fluid stream in significantly fewer numbers and demonstrated fewer E-selectin ligands in flow cytometry than the vector controls. Additionally, qPCR revealed that in comparison to vector controls breast cancer cells expressing Snail or Twist downregulated the expression of α-(1,3) fucosyltransferase and α-(1,4) fucosyltransferase, which catalyze terminal fucosylations necessary for E-selectin ligand function. Interestingly, on E-selectin coated plates breast cancer cells expressing Snail or Twist avoided prolonged exposure to E-selectin by forming mammospheres, yet vector controls did not. Collectively, these data demonstrate that the EMT regulates the expression of E-selectin ligands on breast cancer cells, and causes the cells to become sensitive to culture in an E-selectin rich environment. Citation Format: Grady Earl Carlson, Venktesh Shirure, Alexander O. Ostermann, Emily A. Blaha, Louis F. Delgadillo, David F.J. Tees, Fabian Benencia, Monica Burdick. The epithelial to mesenchymal transition regulates the expression of E-selectin ligands on breast cancer cell lines. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1609.