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DOI: 10.1055/s-0034-1388338
Expression analysis of the macrophage-capping protein (CapG) in single circulating tumor cells (CTCs) isolated from blood samples of breast cancer patients
Objective: Detection of CTCs by the CellSearch system is based on immunomagnetic
enrichment of EpCAM+ cells. Supplementary tools are necessary to isolate and
characterize also EpCAM negative CTCs. CapG was shown to be involved in cancer
cell migration and invasiveness of breast cancer (BC). Aim of this work was to
characterize CapG expression in CTCs of BC patients.
Material and methods: CTCs were enriched and detected in blood samples using the CellSearch system.
EpCAM+ cells were isolated from CellSearch cartridges by the CellCelector system
(ALS, Jena, Germany), an automated scanning microscope and micromanipulator
device. EpCAM- CTCs were isolated from the “waste” of CellSearch System by size
selection. Cytokeratin (CK) positive CTCs were isolated from filters with the
CellCelector and characterized performing immunocytochemistry.
Results: Detection and isolation of single EPCAM+ as well as EPCAM- cells was successfully established using blood samples spiked with low cell numbers of known BC cell lines displaying different EPCAM expression. CellSelector re-analysis of CellSearch cartridges revealed comparable CTC detection rates. EPCAM-/CK+ cells were successfully recovered from CellSearch “waste” samples by size selection and isolated from filter membranes by micromanipulation using CellSelector. CapG
expression of CTCs was detectable performing immuno-cytochemistry directly on
filter membranes or after transfer of CTCs on glass slides. Comparable results were
obtained with CTCs isolated from BC patients.
Conclusion: The established workflow is a reliable method for the detection and isolation of EPCAM+ and/or EPCAM- CTCs. This allows CapG expression analysis of single CTCs in different EPCAM+ and EPCAM- CTC populations.