Triple-negative breast cancer (TNBC) is an aggressive and complex subtype of breast cancer that lacks targeted therapy. TNBC manifests characteristic, extensive intratumoral heterogeneity that promotes disease progression and influences drug response. Single-cell techniques in combination with next-generation computation provide an unprecedented opportunity to identify molecular events with therapeutic potential. Here, we describe the generation of a comprehensive mass cytometry panel for multiparametric detection of 23 phenotypic markers and 13 signaling molecules. This single-cell proteomic approach allowed us to explore the landscape of TNBC heterogeneity, with particular emphasis on the tumor microenvironment. We prospectively profiled freshly resected tumors from 26 TNBC patients. These tumors contained phenotypically distinct subpopulations of cancer and stromal cells that were associated with the patient's clinical status at the time of surgery. We further classified the epithelial-mesenchymal plasticity of tumor cells, and molecularly defined phenotypically diverse populations of tumor-associated stroma. Furthermore, in a retrospective tissue-microarray TNBC cohort, we showed that the level of CD97 at the time of surgery has prognostic potential.

Childhood Leukaemia Investigation Prague Czech Republic

Department of Clinical and Molecular Pathology Institute of Molecular and Translational Medicine Faculty of Medicine and Dentistry Palacký University and University Hospital Olomouc Czech Republic

Department of Comprehensive Cancer Care Masaryk Memorial Cancer Institute Brno Czech Republic

Department of Cytokinetics Institute of Biophysics of the Czech Academy of Sciences Brno Czech Republic

Department of Experimental Biology Faculty of Science Masaryk University Brno Czech Republic

Department of Oncological Pathology Masaryk Memorial Cancer Institute Brno Czech Republic

Department of Pathology EUC Laboratoře CGB a s Ostrava Czech Republic

Department of Pediatric Haematology and Oncology 2nd Faculty of Medicine Charles University Prague and University Hospital Motol Czech Republic

Faculty of Science Charles University Prague Czech Republic

Human Oncology and Pathogenesis Program Memorial Sloan Kettering Cancer Center New York City NY USA

Institute of Biostatistics and Analyses Faculty of Medicine Masaryk University Brno Czech Republic

International Clinical Research Center St Anne's University Hospital Brno Czech Republic

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