Expression of CD24 is associated with HER2 expression and supports HER2-Akt signaling in HER2-positive breast cancer cells.
Bottom Line: We found that expression of CD24 was increased by stable overexpression of HER2.Knockdown of CD24 also suppressed the phosphorylation of Akt, which functions downstream of HER2 and PI3K to promote cell survival.Our results thus indicate that CD24 supports both the expression of HER2 and the consequent activation of PI3K-Akt signaling.
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 examined whether CD24 might affect HER2 expression with the use of RNA interference in the HER2-positive cell line BT-474. The abundance of CD24 and HER2 mRNA was significantly reduced by transfection of the cells with corresponding targeted siRNA (Fig. 5a). Flow cytometry analysis revealed that the percentage of CD24-expressing cells was also markedly reduced by knockdown of CD24 (from 98.9% for cells transfected with a control siRNA to 56.2%). The HER2-negative faction was increased by transfection with the CD24 siRNA (from 71.3% to 59.8%) (Fig. 5b). In contrast, knockdown of HER2 did not affect the proportion of cells expressing CD24 (98.9% for the control siRNA versus 98.1% for the HER2 siRNA) (Fig. 5c). These results imply that CD24 plays a role in maintenance of HER2-positive cells.
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.