Figure 3

CD44⁺/CD24^-/low/ESA⁺ cells in human breast cancer cell lines enrich for tumorigenicity. Shown are representative flow cytometry analysis and gates for epithelial-specific antigen (ESA), CD24 and CD44 sorting. (a) SUM159 cells were sorted on ESA. Dot plots show resulting CD44⁺/CD24^-/low/ESA⁺ or CD44⁺/CD24^-/ESA^- fractions. (b) SUM149 cells were sorted on CD44 and CD24 and subsequently sorted for ESA⁺, shown in histograms. (c) Histological analysis of SUM159 and SUM149 orthotopic tumors. The upper panels present representative hematoxylin and eosin stained sections at 20× magnification of tumors that formed from 5 × 10⁵ unsorted, 1,000 CD44⁺/CD24^-/low/ESA⁺, or 1 × 10⁶ CD44⁺/CD24^-/ESA^- SUM159 cells. Note that the tumor histology from CD44⁺/CD24^-/ESA^- sorted cells is different than that from unsorted or CD44⁺/CD24^-/low/ESA⁺ cells. The lower panels present hematoxylin and eosin stained sections at 20× magnification of tumors that formed from 1 × 10⁵ unsorted, CD44⁺/CD24^-/low/ESA⁺, or CD44⁺/CD24⁺/ESA⁺ sorted SUM149 cells. Note the tumor histology from CD44⁺/CD24⁺/ESA⁺ sorted cells is markedly different from that of the unsorted or the CD44⁺/CD24^-/low/ESA⁺ sorted cells.