Epithelial-to-mesenchymal transition leads to loss of EpCAM and different physical properties in circulating tumor cells from metastatic breast cancer

// Kyung-A Hyun 1, * , Gi-Bang Koo 2, 3, * , Hyunju Han 4 , Joohyuk Sohn 5 , Wonshik Choi 6 , Seung-Il Kim 7 , Hyo-Il Jung 1 , You-Sun Kim 2, 3 1 School of Mechanical Engineering, Yonsei University, Seoul, Korea 2 Department of Biochemistry, Ajou University School of Medicine, Suwon, Korea 3 Department of Biomedical Sciences, Graduate School, Ajou University, Suwon, Korea 4 Institute for Cancer Research, Yonsei University College of Medicine, Seoul, Korea 5 Department of Medical Oncology, Yonsei University College of Medicine, Seoul, Korea 6 Department of Physics, Korea University, Seoul, Korea 7 Department of Surgery, Yonsei University College of Medicine, Seoul, Korea * These authors contributed equally to this paper Correspondence to: Seung-Il Kim, email: skim@yuhs.ac Hyo-Il Jung, email: uridle7@yonsei.ac.kr You-Sun Kim, email: yousunkim@ajou.ac.kr Keywords: epithelial cell adhesion molecule (EpCAM), EpCAM-negative, EMT-induced breast cancer cell, circulating tumor cells (CTCs), label-free separation Received: September 07, 2015 Accepted: March 04, 2016 Published: March 22, 2016 ABSTRACT The dissemination of circulating tumor cells (CTCs) requires the Epithelial-to-Mesenchymal transition (EMT), in which cells lose their epithelial characteristics and acquire more mesenchymal-like phenotypes. Current isolation of CTCs relies on affinity-based approaches reliant on the expression of Epithelial Cell Adhesion Molecule (EpCAM). Here we show EMT-induced breast cancer cells maintained in prolonged mammosphere culture conditions possess increased EMT markers and cancer stem cell markers, as well as reduced cell mass and size by quantitative phase microscopy; however, EpCAM expression is dramatically decreased in these cells. Moreover, CTCs isolated from breast cancer patients using a label-free microfluidic flow fractionation device had differing expression patterns of EpCAM, indicating that affinity approaches reliant on EpCAM expression may underestimate CTC number and potentially miss critical subpopulations. Further characterization of CTCs, including low-EpCAM populations, using this technology may improve detection techniques and cancer diagnosis, ultimately improving cancer treatment.