title: Molecular profiling supports the role of epithelial-to-mesenchymal transition (EMT) in ovarian cancer metastasis.
abstract: BACKGROUND
  While metastasis ranks among the most lethal of all cancer-associated processes, on the molecular level, it remains one of the least well understood. One model that has gained credibility in recent years is that metastasizing cells at least partially recapitulate the developmental process of epithelial-to-mesenchymal transition (EMT) in their transit from primary to metastatic sites. While experimentally supported by cell culture and animal model studies, the lack of unambiguous confirmatory evidence in cancer patients has led to persistent challenges to the model's relevance in humans.
  
  
  METHODS
  Gene expression profiling (Affymetrix, U133) was carried out on 14 matched sets of primary (ovary) and metastatic (omentum) ovarian cancer (serous adenocarcinoma) patient samples. Hierarchical clustering and functional pathway algorithms were used in the data analysis.
  
  
  RESULTS
  While histological examination reveled no morphological distinction between the matched sets of primary and metastatic samples, gene expression profiling clearly distinguished two classes of metastatic samples. One class displayed expression patterns statistically indistinguishable from primary samples isolated from the same patients while a second class displayed expression patterns significantly different from primary samples. Further analyses focusing on genes previously associated with EMT clearly distinguished the primary from metastatic samples in all but one patient.
  
  
  CONCLUSIONS
  Our results are consistent with a role of EMT in most if not all ovarian cancer metastases and demonstrate that identical morphologies between primary and metastatic cancer samples is insufficient evidence to negate a role of EMT in the metastatic process.
authors.affiliation: Integrated Cancer Research Center, School of Biology, and Parker H, Petit Institute of Bioengineering and Biosciences, Georgia Institute of Technology, 315 Ferst Dr,, Atlanta, GA 30332, USA. john.mcdonald@biology.gatech.edu.
authors.forename: Loukia N
authors.initials: LN
authors.lastname: Lili
authors.forename: Lilya V
authors.initials: LV
authors.lastname: Matyunina
authors.forename: L Deette
authors.initials: LD
authors.lastname: Walker
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Wells
authors.forename: Benedict B
authors.initials: BB
authors.lastname: Benigno
authors.forename: John F
authors.initials: JF
authors.lastname: McDonald