Figure 2.

miR-1278 mimic sensitizes CRC cells to oxaliplatin by inducing apoptosis. (A) Cell viability was detected by CCK-8 assay in HT29 and HCT116 cells treated with various concentrations of oxaliplatin for 24 h. The IC50 values of the NC and miR-1278 mimic groups were 124.23 and 81.44 μM, respectively, in HT29 cells as well as86.81 and 42.27 μM, respectively, in HCT116 cells. (B) Cells (5,000 cells per well) were seeded and cultured for 3 days, and cells were then treated with oxaliplatin and cultured for another 4 days. The results showed that the miR-1278 mimic greatly inhibited colony formation of HT29 and HCT116 cells treated with 10 μM oxaliplatin. (C,D) Transfection of miR-1278 significantly reduced the proliferation of HT29 and HCT116 cells treated with 20 μM oxaliplatin as demonstrated by the EdU assay. (E) Comparison of the expression levels of caspase 3, cleaved caspase 3, caspase 9, cleaved caspase 9 and Bax and Bad between the miR-1278 mimic and control groups treated with various concentrations of oxaliplatin is shown as indicated. These proapoptotic proteins were concomitantly upregulated in the miR-1278 mimic group compared to the control group, indicating that transfection of the miR-1278 mimic facilitates apoptosis induced by oxaliplatin in CRC cells. (F) Flow cytometry was performed to quantitatively detect the proportion of apoptosis in each group. The apoptosis rates were 26.62 and 32.20% when HT29 cells were treated with 20 and 40 μM oxaliplatin, respectively, in the miR-1278 mimic group as well as 13.78 and 25.85% in the control group when HT29 cells were treated with 20 and 40 μM oxaliplatin, respectively. The same trend was also observed in HCT116 cells. Oxa, oxaliplatin; NC, negative control; mimic, miR-1278 mimic; *P < 0.05, **P < 0.01, ***P < 0.001.