title: 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 lipids.
  
  
  RESULTS
  The results showed that the polysorbate Tween®20, a non-ionic detergent like organic solvent is able to demask EpCAM on CETC and makes it better accessible to its specific antibody retaining at the same time full cell viability.
  
  
  CONCLUSIONS
  The data presented in this study suggest that EpCAM is present on part of circulating tumor cells in a masked form and that it is possible to demask EpCAM on CETC of breast cancer patients using Tween®20 treatment. But further studies are needed to elucidate the mechanism of demasking.
authors.affiliation: Clinic for Internal Medicine II, Oncology Research Laboratory, Friedrich Schiller University Jena, Jena, Germany. katya.hekimian@med.uni-jena.de
authors.forename: Katya
authors.initials: K
authors.lastname: Hekimian
authors.forename: Ernst-Ludwig
authors.initials: EL
authors.lastname: Stein
authors.forename: Ulrich
authors.initials: U
authors.lastname: Pachmann
authors.forename: Katharina
authors.initials: K
authors.lastname: Pachmann
mesh_terms: D000951:Antigens, Neoplasm / Q000097:blood* / Q000378:metabolism; D001943:Breast Neoplasms / Q000097:blood* / Q000473:pathology*; D015815:Cell Adhesion Molecules / Q000097:blood* / Q000378:metabolism; D002452:Cell Count; D003902:Detergents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D000071858:Epithelial Cell Adhesion Molecule; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D009360:Neoplastic Cells, Circulating / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D011136:Polysorbates / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D000951:Antigens, Neoplasm; D015815:Cell Adhesion Molecules; D003902:Detergents; D000071858:Epithelial Cell Adhesion Molecule; D011136:Polysorbates