title: Identification of enhancer of zeste homolog 2 expression in peripheral circulating tumor cells in metastatic prostate cancer patients: a preliminary study.
abstract: OBJECTIVE
  Enhancer of zeste homolog 2 (EZH2), a kind of transcriptional repressor, is reportedly over-expressed in metastatic prostate cancer. In this study, we analyzed EZH2 mRNA in circulating tumor cells (CTCs) in peripheral blood as a biomarker in patients with metastatic prostate cancer.
  
  
  METHODS
  Ber-EP4 coated immunomagnetic beads were used to harvest CTCs, and mRNA was isolated by oligo- dT conjugated immunomagnetic beads. Reverse transcriptase- polymerase chain reaction for EZH2 mRNA was performed and the expression density was measured. The sensitivity of this test for detection of EZH2 mRNA was determined by serial dilutions of a human prostate cancer cell line. Blood samples were collected from 20 patients each with metastatic or localized prostate cancer and 10 healthy volunteers.
  
  
  RESULTS
  Sensitivity experiments showed that the test was highly sensitive as it could detect 10 tumor cells per 5 mL. EZH2 mRNA expression was obtained from peripheral blood samples of patients and control subjects. EZH2 mRNA expression density in the metastatic prostate cancer group was significantly higher than in the control (p=0.023) and localized prostate cancer groups (p=0.019). There was no difference between the control and localized prostate cancer groups (p > 0.05).
  
  
  CONCLUSIONS
  EZH2 mRNA expression in circulating epithelial cells represents a promising marker for detecting early metastasis in prostate cancer. However, more specific and sensitive techniques for detection of CTCs are needed to avoid mononuclear cell contamination.
authors.affiliation: Department of Urology, Urological Science Institute, Brain Korea 21 Project for Medical Science, College of Medicine, Yonsei University, Seoul, Korea.
authors.forename: Kang Su
authors.initials: KS
authors.lastname: Cho
authors.forename: Hea Young
authors.initials: HY
authors.lastname: Oh
authors.forename: Eun Jin
authors.initials: EJ
authors.lastname: Lee
authors.forename: Sung Joon
authors.initials: SJ
authors.lastname: Hong
mesh_terms: D000368:Aged; D004268:DNA-Binding Proteins / Q000235:genetics*; D000071221:Enhancer of Zeste Homolog 2 Protein; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009360:Neoplastic Cells, Circulating / Q000378:metabolism*; D063151:Polycomb Repressive Complex 2; D011471:Prostatic Neoplasms / Q000097:blood* / Q000235:genetics / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics*; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2