HMGB3 small interfere RNA suppresses mammosphere formation of MDA-MB-231 cells by down-regulating expression of HIF1α

J. Gu, T. Xu, C.-M. Zhang, H.-Y. Chen, Q.-H. Huang, Q. Zhang

Department of Health Check-Up Center, Jinshan Hospital, Fudan University, Shanghai, China. liuzheef@sina.com

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• Oncology

OBJECTIVE: Breast cancer has been proven as the most common malignancy influencing the health of females. This research aimed to clarify the effects of high-mobility group box 3 (HMGB3)-small interfere RNA (HMGB3-siRNA) on the proliferation of breast cancer cells.

MATERIALS AND METHODS: HMGB3-mimic and HMGB3-siRNA lentiviral vectors were structured. The above lentiviral vectors were then transfected into normal breast cells (MCF10A) and breast cancer cells (MDA-MB-231). Cell counting kit-8 (CCK-8) analysis was employed to assess proliferative viabilities of cells. The formation of the mammosphere in breast cancer cells was examined using mammosphere-forming assay. The mRNA expression of Nanog, Sox2, and OCT-4 genes was evaluated using quantitative real time-PCR (qRT-PCR). CD44 positive/CD24 negative (CD44+/CD24-) cell levels were evaluated using flow cytometry assay. The correlation between HMGB3 and hypoxia-inducible factor 1α (HIF1α) was analyzed using Linear-Regression analysis. The interaction between HMGB3 and HIF1α expression was determined using the Dual-Luciferase assay.

RESULTS: HMGB3 expression was remarkably enhanced in breast cancer cells compared to that in normal cells (p<0.05). HMGB3-siRNA significantly decreased the proliferative activity and remarkably suppressed the mammosphere formation compared to that in single MDA-MB-231 cells (p<0.05). HMGB3-siRNA remarkably reduced Nanog, SOX2, and OCT-4 and significantly enhanced CD44+/CD24- cells compared to single MDA-MB-231 cells (p<0.05). HMGB3-siRNA significantly weakened the expression of HIF1α in MDA-MB-231 cells compared to single MDA-MB-231 cells (p<0.05). HMGB3 was positively correlated with HIF1α expression (p<0.05). There was an interaction between HMGB expression and HIF1α expression.

CONCLUSIONS: HMGB3 small interfering RNA suppressed the formation of mammosphere in MDA-MB-231 cells by downregulating the expression of HIF1α.

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