title: Changes in cytoskeletal protein composition indicative of an epithelial-mesenchymal transition in human micrometastatic and primary breast carcinoma cells.
abstract: OBJECTIVE
  The bone marrow is a frequent and clinically important homing site for early disseminated breast cancer cells. Here, we aimed to profile the protein expression of these cells using unique cell line models and to evaluate the prognostic relevance of candidate gene expression for breast cancer patients.
  
  
  METHODS
  To identify expression patterns characteristic for micrometastatic cells, three different cell lines (BC-K1, BC-P1, and BC-S1) established by SV40 immortalization of cancer cells isolated from the bone marrow of patients with breast cancer were compared with MCF-7 breast cancer and SV40 immortalized normal breast ductal cells (MTSV-1.7) using two-dimensional gel electrophoresis followed by MALDI-ToF analysis. The prognostic significance and clinicopathologic associations of selected differentially expressed proteins were evaluated using high-density breast cancer tissue microarrays.
  
  
  RESULTS
  In contrast to MCF-7 and MTSV1-7 reference cell lines, all micrometastatic cancer cell lines displayed loss of epithelial cytokeratins (CK8, CK18, and CK19) and ectopic expression of vimentin commonly present in mesenchymal cells. Immunohistochemical analysis of 2,517 samples of breast cancer further showed that loss of cytokeratin and ectopic vimentin expression were significantly associated with a higher tumor grade, high mitotic index, and negative estrogen/progesterone-receptor status. Although in univariate analyses significantly related to clinical outcome, none of the cytokeratins analyzed were independently associated with either overall or cancer-specific survival.
  
  
  CONCLUSIONS
  Micrometastatic cancer cells exhibit marked changes in the expression pattern of cytoskeletal proteins indicative of an epithelial-mesenchymal transition. This phenotypical change could already be detected in primary tumors and is associated with the aggressive behavior of breast cancer cells in vivo.
authors.affiliation: Institute of Tumor Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Birthe
authors.initials: B
authors.lastname: Willipinski-Stapelfeldt
authors.forename: Sabine
authors.initials: S
authors.lastname: Riethdorf
authors.forename: Volker
authors.initials: V
authors.lastname: Assmann
authors.forename: Ute
authors.initials: U
authors.lastname: Woelfle
authors.forename: Thomas
authors.initials: T
authors.lastname: Rau
authors.forename: Guido
authors.initials: G
authors.lastname: Sauter
authors.forename: Jochen
authors.initials: J
authors.lastname: Heukeshoven
authors.forename: Klaus
authors.initials: K
authors.lastname: Pantel
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D003598:Cytoskeletal Proteins / Q000032:analysis*; D015180:Electrophoresis, Gel, Two-Dimensional; D004848:Epithelium / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007381:Intermediate Filament Proteins / Q000032:analysis; D007633:Keratins / Q000032:analysis; D008648:Mesoderm / Q000378:metabolism / Q000473:pathology*; D015999:Multivariate Analysis; D009362:Neoplasm Metastasis / Q000473:pathology; D011379:Prognosis; D020543:Proteome / Q000032:analysis; D040901:Proteomics / Q000379:methods; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D016019:Survival Analysis; D046888:Tissue Array Analysis / Q000379:methods; D014746:Vimentin / Q000032:analysis
chemical_list: D003598:Cytoskeletal Proteins; D007381:Intermediate Filament Proteins; D020543:Proteome; D014746:Vimentin; D007633:Keratins