Figure 1

Image galleries of representative biomarker profiles in CTCs. (a) Image galleries after isolation, cytomorphological analysis, and detection of cytokeratin-positive (CK⁺) cells (red staining), estrogen receptor (ER), and epidermal growth factor receptor (EGFR) in MCF7 cell tumor lines. (b) Expression of different markers in patients with breast cancer through combination of stained CK⁺ cells (red) with ER or progesterone receptor (PR) (blue). ER- and PR-specific immunofluorescence (IF) of circulating tumor cells (CTCs) was determined with Alexa 355. ER-specific IF of CTCs of a heterogeneous case is shown. (c) EFGR protein expression was detected by immunocytochemistry by using anti-human-EGFR antibodies (blue). EGFR-specific IF of CTCs was determined with Alexa 355. Human epidermal growth factor receptor 2 (HER2) and topoisomerase 2α (TOP2A) gene amplification was determined by fluorescence in situ hybridization (FISH) assay before immunophenotyping with anti-CK antibody (green). Image demonstrates HER2 amplification (red dots) and TOP2A amplification (green dots) compared to centromere 17 (CEP17; blue dots) in CTCs.