Effect miR-214-3p on proliferation and apoptosis of breast cancer cells by targeting survivin protein.

OBJECTIVE: Studies showed that microRNAs (miRs) play an important role in the development of breast cancer. It has been shown that there were significant differences between the expression levels of serum miR-214-3p in breast cancer patients and healthy controls. Since survivin is involved in cell cycle and apoptosis, this study aims to investigate the effect of miR-214-3p on the proliferation and apoptosis of breast cancer cells. MATERIALS AND METHODS: Dual-Luciferase reporter system was used to validate the cell cycle-related target gene survivin. miRanda and TargetScan were used to predict miR-214-3p target genes. Lipofectamine 2000 was used to transfect the miR-214-3p mimics, miR-NC into the MCF-7 cells. The quantitative Real Time-PCR (qRT-PCR) was used to detect the expression levels of miR-214-3p and survivin. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay was used to examine the cell proliferation of breast cancer cells. The flow cytometry assay was used to evaluate the apoptosis of breast cancer cells. RESULTS: Dual-Luciferase reporter assay showed that cells co-transfected with wild-type vector and miR-214-3p mimics had significant lower ratios of hRluc/Luc fluorescence compared to that of the control group (p<0.05). The expression level of miR-214-3p was increased along with the increase of time after transfection, whereas the expression level of survivin mRNA was decreased along with the increase of time post transfection. This result suggests that miR-214-3p regulates the mRNA expression of survivin. Transfection of miR-214-3p inhibitor increased the proliferation of MCF-7 cells and transfection of miR-214-3p mimics decreased the proliferation of MCF-7 cells compared to control group (p<0.05). CONCLUSIONS: Survivin gene is a downstream target of miR-214-3p in breast cancer cells. The expression of miR-214-3p and survivin is correlated with the proliferation and apoptosis of breast cancer cells.

Anti-proliferative effect of digoxin on breast cancer cells via inducing apoptosis.

OBJECTIVE: Digoxin is a kind of plant-derived cardiac glycoside that is mainly used to treat heart diseases, especially in congestive heart failure or arrhythmia. However, its potentiality presented in anti-tumor remains unexplored. The purpose of this study was designed to investigate the beneficial pharmacological activity of digoxin on breast cancer cell line (MDA-MB-231, MM231). MATERIALS AND METHODS: The methyl thiazolyl tetrazolium (MTT) assay was utilized to detect the proliferation of the breast cancer MM231. The apoptotic cell numbers were determined by the flow cytometry analysis. The expressions of Bcl-2 (B-cell lymphoma-2) and Bax (Bcl2-associated X protein) were detected by Western blot analysis. RESULTS: Digoxin dose-dependently blocked the cell growth of the breast cancer MM231 through MTT assay, whereas the apoptotic numbers were significantly elevated as reflected in acridine orange staining and flow cytometry analysis. In addition, findings from Western blotting method indicated that digoxin intervention showed reduced Bcl-2 expression and elevated Bax level in MM231 cells, characterized by increased Bax/Bcl-2 ratio. CONCLUSIONS: Digoxin plays a potential anti-tumor role in breast cancer in vitro, possibly by inducing mitochondria-dependent apoptosis.