Figure 6.

miR-1278 sensitizes CRC cells to vitamin D by depressing the expression of CYP24A1. (A,B) Cell viability was detected by CCK-8 assay in HT29 and HCT116 cells treated with various concentrations of vitamin D for 24 h. The IC50 values of the NC and miR-1278 mimic groups were 1.06 and 0.58 μM, respectively, in HT29 cells and 1.91 and 1.26 μM, respectively, in HCT116 cells. (C) Transfection of miR-1278 markedly inhibited the proliferation of HCT116 cells treated with 0.5 μM vitamin D as demonstrated by the EdU assay. (D) The expression of cleaved caspase 3 and cleaved caspase 9 was increased in the miR-1278 mimic group compared to the control group after treatment with the same concentration of vitamin D. (E) SDZ285-428 is a specific inhibitor of CYP24A1. Either the miR-1278 mimic or SDZ285-428 led to an improved apoptosis rate after vitamin D treatment, and the combination treatment of the miR-1278 mimic and SDZ285-428 resulted in a further enhancement of apoptosis in HT29 cells. VitD, Vitamin D; NC, negative control; Mimic, miR-1278 mimic.