Figure 2

MiR-20b directly targets the 3′-UTR of PTEN. (A) Sequence alignment of the miR-20b base-paring site in the 3′-UTR of PTEN mRNA. The region complementary to the seven nucleotides of miR-20b is highly conserved among human, chimpanzee, mouse, rat, and xenopus. The “seed” sequence of miR-20b that is complementary to PTEN is shown in the box. The mutant sequence (PTEN-3′-UTR-mut) is identical to the wild-type sequence (PTEN-3′-UTR-wt) except the mutated nucleotides are shown in italics. (B) Luciferase assays in ZR-75-30 and MCF-7 breast cancer cells. Cells were cotransfected with wt/mut 3′-UTR with miR-20b mimics or negative control as indicated. Forty-eight hours after transfection, luciferase activity was detected using Dual-Luciferase Reporter Assay System according to the manufacturer’s instruction. Error bars represent mean ± SD from three independent experiments. *, P < 0.05 when compared with corresponding negative control.