title: Gene expression profile of circulating tumor cells in breast cancer by RT-qPCR.
abstract: BACKGROUND
  Circulating tumor cells (CTCs) have been associated with prognosis especially in breast cancer and have been proposed as a liquid biopsy for repeated follow up examinations. Molecular characterization of CTCs is difficult to address since they are very rare and the amount of available sample is very limited.
  
  
  METHODS
  We quantified by RT-qPCR CK-19, MAGE-A3, HER-2, TWIST1, hTERT α+β+, and mammaglobin gene transcripts in immunomagnetically positively selected CTCs from 92 breast cancer patients, and 28 healthy individuals. We also compared our results with the CellSearch system in 33 of these patients with early breast cancer.
  
  
  RESULTS
  RT-qPCR is highly sensitive and specific and can detect the expression of each individual gene at the one cell level. None of the genes tested was detected in the group of healthy donors. In 66 operable breast cancer patients, CK-19 was detected in 42.4%, HER-2 in 13.6%, MAGE-A3 in 21.2%, hMAM in 13.6%, TWIST-1 in 42.4%, and hTERT α+β+ in 10.2%. In 26 patients with verified metastasis, CK-19 was detected in 53.8%, HER-2 in 19.2%, MAGE-A3 in 15.4%, hMAM in 30.8%, TWIST-1 in 38.5% and hTERT α+β+in 19.2%. Our preliminary data on the comparison between RT-qPCR and CellSearch in 33 early breast cancer patients showed that RT-qPCR gives more positive results in respect to CellSearch.
  
  
  CONCLUSIONS
  Molecular characterization of CTCs has revealed a remarkable heterogeneity of gene expression between breast cancer patients. In a small percentage of patients, CTCs were positive for all six genes tested, while in some patients only one of these genes was expressed. The clinical significance of these findings in early breast cancer remains to be elucidated when the clinical outcome for these patients is known.
authors.affiliation: Department of Chemistry, University of Athens, University Campus, 15771 Athens, Greece.
authors.forename: Areti
authors.initials: A
authors.lastname: Strati
authors.forename: Athina
authors.initials: A
authors.lastname: Markou
authors.forename: Cleo
authors.initials: C
authors.lastname: Parisi
authors.forename: Eleni
authors.initials: E
authors.lastname: Politaki
authors.forename: Dimitris
authors.initials: D
authors.lastname: Mavroudis
authors.forename: Vasilis
authors.initials: V
authors.lastname: Georgoulias
authors.forename: Evi
authors.initials: E
authors.lastname: Lianidou
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D009360:Neoplastic Cells, Circulating / Q000378:metabolism*; D011379:Prognosis; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor