Demasking of epithelial cell adhesion molecule (EpCAM) on circulating epithelial tumor cells by Tween®20 treatment in breast cancer patients

Abstract Background: The epithelial cell adhesion molecule (EpCAM) embedded in the plasma membrane of circulating epithelial tumor cells (CETC) is used for detection and enrichment of circulating tumor cells in peripheral blood and as a target for anti-epithelial antibodies elicited during immune response in anti-tumor immunization. Although an efficient immune response against EpCAM can be generated, the clinical application of such approaches has not been successful so far and the detection of circulating epithelial cells is highly variable. One reason for these discrepancies may be that not all circulating tumor cells are equally accessible for the specific antibody. A possible reason might be masking of EpCAM by glycoproteins or membrane lipoproteins preventing antibody binding. Methods: We have tested the application of detergents as demasking agents known to be successful in demasking red blood cell epitopes and determined how and in which way they affect integral membrane proteins and membrane lipi...