title: Identification of markers associated with highly aggressive metastatic phenotypes using quantitative comparative proteomics.
abstract: BACKGROUND
  The spread of cancer cells from a primary tumor to form metastases at distant sites is a complex process that remains poorly defined. Certain tumor cells are more aggressive and thus lead to rapid development of multiple distant metastases. Here, we identify proteins associated with these aggressive phenotypes.
  
  
  METHODS
  To identify proteins associated with cancer cell aggressiveness, we used comparative, quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteome analysis of a unique metastasis model comprised of three isogenic human breast cancer cell lines that are equally tumorigenic in mice, but display different metastatic potentials ranging from non-metastatic, intermediate-metastatic and highly-metastatic. The altered expression of selected proteins was subsequently confirmed by immunocyto- and immunohistochemistry.
  
  
  RESULTS
  The difference in metastatic capabilities was initially confirmed using live animal imaging. Comparative, quantitative proteomics identified 414 proteins, out of which 44 exhibited altered expression between the metastatic and non-metastatic cell lines. The proteins correlating with the aggressiveness of metastasis included leucine-rich repeat containing 59 (LRRC59), while CD59 and chondroitin sulfate proteoglycan 4 (CSPG4) exhibited an inverse correlation with metastatic capability. The altered expression levels of these proteins were biochemically confirmed, as well as demonstrated in xenografts generated from these cell lines. This analysis further demonstrated that the three proteins were associated with the aggressiveness of metastasis rather than metastasis colonization per se.
  
  
  CONCLUSIONS
  Our study provides novel insights into key proteins associated with the metastatic potential of breast cancer cells and identified LRRC59, CD59 and CSPG4 as candidates that merit further study.
authors.affiliation: Department of Cancer and Inflammation Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark.
authors.forename: Mikkel G
authors.initials: MG
authors.lastname: Terp
authors.forename: Rikke R
authors.initials: RR
authors.lastname: Lund
authors.forename: Ole N
authors.initials: ON
authors.lastname: Jensen
authors.forename: Rikke
authors.initials: R
authors.lastname: Leth-Larsen
authors.forename: Henrik J
authors.initials: HJ
authors.lastname: Ditzel
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D018957:CD59 Antigens / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D011508:Chondroitin Sulfate Proteoglycans / Q000235:genetics / Q000378:metabolism; D002853:Chromatography, Liquid; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009362:Neoplasm Metastasis / Q000175:diagnosis*; D009363:Neoplasm Proteins / Q000302:isolation & purification* / Q000378:metabolism; D010641:Phenotype; D040901:Proteomics / Q000379:methods*; D053719:Tandem Mass Spectrometry; D000099216:Chondroitin Sulfate Proteoglycan 4
chemical_list: D014408:Biomarkers, Tumor; D018957:CD59 Antigens; D011508:Chondroitin Sulfate Proteoglycans; D008565:Membrane Proteins; D009363:Neoplasm Proteins; C101390:CSPG4 protein, human; D000099216:Chondroitin Sulfate Proteoglycan 4; C574205:LRRC59 protein, human; C051590:CD59 protein, human