EpCAM-expressing circulating tumor cells in colorectal cancer



Several studies have raised the issue of the inadequacy of CellSearch® to detect the entire pool of circulating tumor cells (CTCs) from blood of cancer patients, suggesting that cells expressing low levels of epithelial cell adhesion molecule (EpCAM) are not recognized by the capture reagent. In this exploratory study, we aimed to evaluate the status of EpCAM in CTCs isolated from a group of metastatic colorectal cancer patients, in 40% of whom, CTC had been found to be undetected by the CellSearch® system.


CTCs were analyzed using both a microfiltration method (ScreenCell) and CellSearch® in parallel. Furthermore, since EpCAM exists in 2 different variants, we investigated the presence of both its intracellular domain (EpICD) and extracellular domain (EpEX) through immunofluorescence staining of CTCs on filters.


Results from immunofluorescence experiments demonstrated that, overall, EpICD and/or EpEX was expressed in 176 CTCs detected by ScreenCell, while the CellSearch® system was able to capture only 10 CTCs.


This is the first demonstration that the low sensitivity of CellSearch® to detect CTCs in colorectal cancer patients is not due to the lack of EpCAM.

Int J Biol Markers 2017; 32(4): e415 - e420




Chiara Nicolazzo, Cristina Raimondi, Federica Francescangeli, Simona Ceccarelli, Patrizia Trenta, Valentina Magri, Cinzia Marchese, Ann Zeuner, Angela Gradilone, Paola Gazzaniga

Article History


Financial support: This work was supported by the Italian Ministry for University and Research (MIUR) (grant number C26N147NSX) and A.R.Ger.On. Onlus.
Conflict of interest: The authors have no conflicts of interest to declare.

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  •  Circulating Tumor Cells Unit, Department of Molecular Medicine, Sapienza University of Rome, Rome - Italy
  •  Department of Hematology, Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome - Italy
  •  Department of Experimental Medicine, Sapienza University of Rome, Rome - Italy
  •  Department of Radiological, Oncological and Anatomopathological Sciences, Sapienza University of Rome, Rome - Italy
  • Angela Gradilone and Paola Gazzaniga contributed equally to this work.

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