PURPOSE: 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.
PATIENTS AND 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).
CONCLUSION: 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.