MicroRNA expression in CD44-positive BRCA1-mutant breast cancer cells after adding anticancer drug gemcitabine

Abstract

MicroRNA （miRNA） expression of cancer stem-like cells in cultured breast cancer cells （BRCA1-mutant MDA-MB-436 and BRCA1-wild type MDA-MB-231） was examined using CD44, a breast cancer stem cell marker with or without the addition of the anticancer drug, gemcitabine. CD44-positive cells were collected using the bead method, and the expression of 84 miRNAs was examined using a miRNA PCR array. Changes in miRNA expression induced by gemcitabine were analyzed using the ΔΔCt method. The expression of the miR-1, miR-155, miR-186, and miR-31 were higher in CD44-positive MDA-MB-436 cells than in CD44-positive MDA-MB-231 cells. The higher expression of miR-1 and miR-186 were observed in both MDA-MB-436 and MDA-MB-231 cells after adding gemcitabine. The expression of miR-155 and miR-31 was increased in MDA-MB-436 after adding gemcitabine but decreased in MDA-MB-231. Our results suggested that BRCA1-mutant breast cancer stem cells are characterized by increased miR-1, miR-31, miR-155, and miR-186. Moreover, miR-155 and miR-31 are not decreased after administration of anticancer drugs, which may be associated with therapeutic resistance and malignancy.