Differential expression of miR-200c in breast cancer stem cells

Breast cancer has become the most popular malignant tumors in females. Breast cancer stem cells (BCSCs) play an important role in metastasis and recurrence. Previous study showed close correlation between miR-200c and behavioral regulation of breast cancer stem cells. This study aimed to investigate differential expression of miR-200c in breast cancer stem cells, and its role in regulation tumor formation property. DNA microchip assay and qRT-PCR analyzed differential expression of microRNA between BCSCs and non-tumor formation NTG cells. Bioinformatics and luciferase reporter gene assay determined targeted site of miR-200c. MiR mimic and inhibitor were transfected to change miR-200c expression level, followed by Western Blot for detecting BMI1 gene expression. Cell clonal assay determined cell proliferation, whilst tumor xenograft was performed to analyze tumor formation potency. MiR-200c was down-regulated in BCSCs compared to NTG cells (P<0.05). Bioinformatics and luciferase reporter gene assay attributed BMI1 gene as targeting site of miR-200c. Transfection of miR-200c and inhibitor altered miR-200c expression. Results showed that miR-200c could suppress BMI1 expression, and suppressed proliferation and tumor formation rate (P<0.05). Compared to NTG cells, BCSCs has significantly down-regulated expression of miR-200c. BCSCs facilitate BMI1 gene expression via inhibiting miR-200c expression, further elevating BCSCs proliferation and tumor formation potency.