Enrichment of CD44+/CD24+ cells predicts chemoresistance in luminal breast cancer

Abstract Purpose: Chemoresistant cells are pre-existing and adaptively selected by chemotherapy. The biomarkers of chemoresistant cells in luminal breast cancer remain unknown. The expression of CD44 and CD24 are associated with breast cancer progression. This study aimed to explore the proportion change of differently expressed CD44/CD24 tumor cells during the induction of chemoresistance.Methods: Tumor specimens of patients with luminal breast cancer resistant and sensitive to chemotherapy drugs regimens were collected. The proportion of CD44+/−CD24+/− tumor cells in the two groups of samples was compared by immunofluorescence staining. MCF-7 and T47D variants resistant to chemotherapy drugs were induced by pulse selection of the parental cells with the IC90 value of the two drugs for 7 weeks. Changes in the proportion of CD44+/−CD24+/− cells during the induction of chemoresistance were observed and compared using flow cytometry.Results: The proportion of CD44+CD24+ cells in the tumor tissues of chemoresistant patients was significantly higher than chemosensitive patients. At the endpoint of chemoresistance induction, the proportions of CD44+CD24+ cells reached 86.27%, 84.41%, 83.03%, and 85.12% in MCF-7/EPI, MCF-7/DOC, T47D/EPI, and T47D/DOC, respectively. The proportion of CD44+CD24− cells increased briefly and then decreased to nearly the pre-induction level (3.01%). The proportion of CD44−CD24− and CD44−CD24+ cells in the four chemoresistant variants was less than 5% at the endpoint of chemoresistance induction. Conclusions: The enrichment of CD44+CD24+ cells predicts chemoresistance in luminal breast cancer. CD44+CD24+ is a biomarker for chemoresistant luminal breast cancer cells.