Yonsei Med J.  2007 Dec;48(6):1009-1014. 10.3349/ymj.2007.48.6.1009.

Identification of Enhancer of Zeste Homolog 2 Expression in Peripheral Circulating Tumor Cells in Metastatic Prostate Cancer Patients: A Preliminary Study

• Cho KS
• Oh HY
• Lee EJ
• Hong SJ

• KMID: 1786217
• DOI: http://doi.org/10.3349/ymj.2007.48.6.1009

Abstract

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 5mL. 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.

Keyword

Prostate cancer; metastasis; circulating tumor cell; enhancer of zeste homolog 2

MeSH Terms

Aged
DNA-Binding Proteins/*genetics
Humans
Male
Middle Aged
Neoplasm Metastasis
Neoplastic Cells, Circulating/*metabolism
Prostatic Neoplasms/*blood/genetics/pathology
RNA, Messenger/genetics/metabolism
Reverse Transcriptase Polymerase Chain Reaction
Transcription Factors/*genetics
Tumor Cells, Cultured

Figure

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  Fig. 1 Sensitivity of reverse transcriptase-polymerase chain reaction for enhancer of zeste homolog 2. The numbers 1-10,000 indicate the number of PC3 cells in 5 mL of phosphate buffered saline.

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  Fig. 2 Representative results of reverse transcriptase-polymerase chain reaction for enhancer of zeste homolog 2 in peripheral blood samples obtained from healthy volunteers and patients with localized prostate cancer or metastatic prostate cancer.

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  Fig. 3 Expression density of reverse transcriptase-polymerase chain reaction for enhancer of zeste homolog 2 in peripheral blood samples obtained from subjects as measured by the Quantity One® program (*p < 0.05 by Mann-Whitney U test, compared to the healthy group or localized prostate cancer group).

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