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Clin Transl Oncol. 2018 Sep 14. doi: 10.1007/s12094-018-1941-1. [Epub ahead of print]

Epithelial membrane protein 2: a novel biomarker for circulating tumor cell recovery in breast cancer.

Author information

Key Laboratory for Translational Medicine and the Division of Breast Surgery, The First Affiliated Hospital of Huzhou University School of Medicine, Huzhou, 313000, Zhejiang, China.
Department of Medicine and Moores Cancer Center, University of California San Diego, La Jolla, CA, 92093, USA.
Calidi Biotherapeutics, San Diego, CA, 92121, USA.
Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale School of Medicine, Yale Cancer Center, New Haven, CT, 06520, USA.
Division of Gastrointestinal SurgeryThe First Affiliated Hospital and the Department of Clinical Medicine, Jiaxing University School of Medicine, Jiaxing, 314001, Zhejiang, China.
Department of Medicine and Moores Cancer Center, University of California San Diego, La Jolla, CA, 92093, USA.



EpCAM is a common marker used in the detection of circulating tumor cells (CTC). Disseminated cancer cells display the characteristics of epithelial-to-mesenchymal transition events. The purpose of this study was to assess the potential of epithelial membrane protein 2 (EMP2) as a novel biomarker for CTC retrieval in breast cancer.


MCF7 and MDA-MB-231 cells were stained with either anti-EpCAM or anti-EMP2 mAbs, respectively, followed by flow cytometric assay to measure their expression levels. PBMCs isolated from healthy donors were used for breast cancer cell spiking. CD45-depleted PBMCs from breast cancer patients' blood were used for CTC capturing. Immunomagnetic separation was used to enrich breast cancer cells. Cytospin centrifugation was performed to concentrate the captured cells, followed by immunofluorescence staining with anti-CD45 mAb, anti-pan cytokeratin mAb and DAPI. Fluorescent images were taken using a confocal microscope for CTC counts.


MDA-MB-231 cells had 2.56 times higher EMP2 expression than MCF7 cells, and EMP2 had a significantly higher capture efficiency than EpCAM for MCF7 cells. Furthermore, anti-EMP2 was capable of capturing MCF7 cells that escaped in the flow-through of anti-EpCAM. Likewise, EMP2 had a significantly higher capture efficiency on MDA-MB-231 cells when compared to MCF7 cells. Most importantly, EMP2 biomarker was successfully used for CTC capture in patients with primary breast cancer.


EMP2 is superior to EpCAM for capturing both MCF7 and MDA-MB-231 cells. Additionally, EMP2 is a novel biomarker and capable of capturing breast cancer cells in patient blood samples.


Biomarker; Breast cancer; Capture; Circulating tumor cells; Epithelial membrane protein 2


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