Fig. 3

Results of dual luciferase reporter assay in HEC-1-A cells. From the bioinformatics database, miR-23a was predicted to target the SMAD3 (a) or SMAD5 (b) gene at a site in the 3′-UTR. To test the possibility of a direct link between miR-23a and human SMAD3 or SMAD5, we performed a dual luciferase reporter assay in HEC-1-A cells. A significant decrease in relative luciferase activity was observed when pGL3-SMAD3-3′-UTR was cotransfected with a miR-23a mimic. Whereas, we didn’t find any significant decrease in relative luciferase activity when pGL3-SMAD5-3′-UTR was cotransfected with a miR-23a mimic. In the presence of the miR-23a mimic, expression of the renillaluciferase reporter was repressed 2.9-fold compared with the vector-only control. Significantly, partial deletion of the perfectly complementary sites in the 3′-UTR of SMAD3 abolished the suppressive effect due to the disruption of the interaction between miR-23a and SMAD3. Triplicate assays were performed for each sample (n = 6 per group) (*P < 0.05)