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. 2017 Sep 20;14(6):6929–6936. doi: 10.3892/ol.2017.7007

Figure 5.

Figure 5.

Effect of miR-21 on DOX chemoresistance in breast cancer cells induced by TGF-β1. (A) Cell viability was determined using an MTT assay in MCF-7 cells transfected with anti-miR-21 or scramble anti-miR-NC at 48 h following exposure to 5 ng/ml TGF-β1 in combination with different concentrations of DOX (0, 1, 10, 50, 100, 200 and 1,000 nM). Downregulation of miR-21 decreased resistance in MCF-7 cells to DOX induced by TGF-β1. (B) MTT analyzed alterations in IC50 values of DOX in MCF-7 cells, following exposure to 5 ng/ml TGF-β1 alone or transfection with anti-miR-21 or scramble anti-miR-NC. Compared with the IC50 values of DOX in the control group, TGF-β1 increased the IC50 value of DOX in MCF-7 cells. Downregulation of miR-21 decreased the IC50 value of DOX in MCF-7 cells, compared with the anti-miR-NC and TGF-β1 group. Data are presented as the mean ± standard error of the mean of three independent assays. **P<0.01. miR, microRNA; DOX, doxorubicin; TGF-β1, transforming growth factor β1; NC, negative control; IC50, half maximal inhibitory concentration.