title: Effects of EpCAM overexpression on human breast cancer cell lines.
abstract: BACKGROUND
  Recently, EpCAM has attracted major interest as a target for antibody- and vaccine-based cancer immunotherapies. In breast cancer, the EpCAM antigen is overexpressed in 30-40% of all cases and this increased expression correlates with poor prognosis. The use of EpCAM-specific monoclonal antibodies is a promising treatment approach in these patients.
  
  
  METHODS
  In order to explore molecular changes following EpCAM overexpression, we investigated changes of the transcriptome upon EpCAM gene expression in commercially available human breast cancer cells lines Hs578T and MDA-MB-231. To assess cell proliferation, a tetrazolium salt based assay was performed. A TCF/LEF Reporter Kit was used to measure the transcriptional activity of the Wnt/β-catenin pathway. To evaluate the accumulation of β-catenin in the nucleus, a subcellular fractionation assay was performed.
  
  
  RESULTS
  For the first time we could show that expression profiling data of EpCAM transfected cell lines Hs578TEpCAM and MDA-MB-231EpCAM indicate an association of EpCAM overexpression with the downregulation of the Wnt signaling inhibitors SFRP1 and TCF7L2. Confirmation of increased Wnt signaling was provided by a TCF/LEF reporter kit and by the finding of the nuclear accumulation of ß-catenin for MDA-MB-231 EpCAM but not Hs578T EpCAM cells. In Hs578T cells, an increase of proliferation and chemosensitivity to Docetaxel was associated with EpCAM overexpression.
  
  
  CONCLUSIONS
  These data show a cell type dependent modification of Wnt signaling components after EpCAM overexpression in breast cancer cell lines, which results in marginal functional changes. Further investigations on the interaction of EpCAM with SFRP1 and TCF7L2 and on additional factors, which may be causal for changes upon EpCAM overexpression, will help to characterize unique molecular properties of EpCAM-positive breast cancer cells.
authors.affiliation: Laboratory for Experimental Oncology, Tyrolean Cancer Research Institute, Innrain 66, 6020 Innsbruck, Austria.
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Gostner
authors.forename: Dominic
authors.initials: D
authors.lastname: Fong
authors.forename: Oliver A
authors.initials: OA
authors.lastname: Wrulich
authors.forename: Florian
authors.initials: F
authors.lastname: Lehne
authors.forename: Marion
authors.initials: M
authors.lastname: Zitt
authors.forename: Martin
authors.initials: M
authors.lastname: Hermann
authors.forename: Sylvia
authors.initials: S
authors.lastname: Krobitsch
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Martowicz
authors.forename: Guenther
authors.initials: G
authors.lastname: Gastl
authors.forename: Gilbert
authors.initials: G
authors.lastname: Spizzo
mesh_terms: D000951:Antigens, Neoplasm / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D015815:Cell Adhesion Molecules / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D048708:Cell Growth Processes / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D000077143:Docetaxel; D000071858:Epithelial Cell Adhesion Molecule; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D018613:Microscopy, Confocal; D011499:Protein Processing, Post-Translational; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism; D043823:Taxoids / Q000494:pharmacology; D051153:Wnt Proteins / Q000378:metabolism; D051176:beta Catenin / Q000378:metabolism
chemical_list: D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D015815:Cell Adhesion Molecules; C499379:EPCAM protein, human; D000071858:Epithelial Cell Adhesion Molecule; D043823:Taxoids; D051153:Wnt Proteins; D051176:beta Catenin; D000077143:Docetaxel