Figure 1.

CD44, CD24 and ALDH expression in breast cancer cell lines is subtype dependent (A–B) Flow cytometry analysis of ALDH, CD44 and CD24 expression in different molecular subtypes of breast cancer. Cells were treated with ALDEFLUOR reagent and double stained with anti-CD44-APC (allophycocyanin) and anti-CD24-PerCP-eFluor 710. The accuracy of the double immunostaining was confirmed by comparison with single immunostaining. FSC—forward scatter. ALDH^br cells were the highest in HER2-OE cell lines, CD44^−/low/CD24^−/low in luminal and CD44^high/CD24^−/low in triple-negative cell lines (Supplementary Figure S1). (C) Representative gating for the selection of CD44^high/CD24^−/low and CD44^−/low/CD24^−/low cells. (D) Representative immunofluorescence images showing the expression of CD24 (green), CD44 (red) and DAPI (blue) in breast cancer cell lines. Cells were stained with primary anti-CD24 and anti-CD44 antibodies. Scale bar = 100 μm. (E–F) Comparison of average fluorescence intensities of CD44 and CD24. (G) The relative mRNA expression of CD24 and CD44 by qRT-PCR shows that luminal cell lines have a low expression of both CD44 and CD24. All mRNA expression compared to Hs578T. Data represent the mean ± SD of three independent experiments; ** p < 0.01, *** p < 0.001, and **** p < 0.0001.