Expression of CD24 is associated with HER2 expression and supports HER2-Akt signaling in HER2-positive breast cancer cells.
Bottom Line: However, resistance to HER2-targeted therapy remains a major clinical problem.HER2-positive breast tumors are predominantly positive for CD24, suggesting that the expression of the two molecules is related.Flow cytometry thus revealed that the percentage of CD24-positive cells was markedly higher in the HER2-positive fraction than in the HER2-negative fraction.
Affiliation: Division of Gene Regulation, Institute for Advanced Medical Research, School of Medicine, Keio University, Tokyo, Japan; Department of Breast Oncology, Tokyo Medical University, Tokyo, Japan.Show MeSH
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Mentions: We next examined the expression of HER2, CD24 and CD44 in five HER2-positive breast cancer cell lines: BT-474, HCC202, SKBR3, ZR-75-1 and HCC1569. Flow cytometry showed that the CD44+CD24− subpopulation constituted 2.65%, 0.057%, 0.143%, 1.42% and 91.7% of cells in these lines, respectively (Fig. 4a). Next, we measured CD24 expression levels in the top 20% fraction of HER2-high cells and the bottom 20% fraction of HER2-low/- cells of each cell line (Fig. 4b). For BT-474, which has an amplification of HER2 gene, the CD24-positive subpopulation was 97.1% in the HER2-high fraction but 73.4% in the HER2-low/- fraction. For ZR-75-1, which has a normal level of HER2, the proportion of CD24-positive cells was 97.2% in the HER2-high fraction but only 27.4% in the HER2-low/- fraction (Fig. 4c). A similar pattern was apparent for the other three HER2-amplified cell lines. The expression of CD24 was thus higher in HER2-high cells than in HER2-low/- cells for all five breast cancer cell lines.
Affiliation: Division of Gene Regulation, Institute for Advanced Medical Research, School of Medicine, Keio University, Tokyo, Japan; Department of Breast Oncology, Tokyo Medical University, Tokyo, Japan.