Suppression of IL-8 expression by rescue-competent miRs in CF lung epithelial cells. In silico analyses indicate that both miR-16 and miR-302a have binding sites at the target IL-8 mRNA 3′-UTR sequences. IB3-1 CF lung epithelial cells (2 × 105) were transfected with miR mimics, (a) miR-16 (25 nM) or (b) miR-302a (30 nM) for 48 h with siPort transfection reagent. The RNA was isolated after treatment with actinomycin D (5 μgml − 1) for the indicated time intervals (0, 1, 2 and 3 h). The remaining IL-8 mRNA was analyzed by qRT-PCR (*P<0.05). The corresponding secreted IL-8 protein was measured using ELISA (*P<0.05). (c) Luciferase reporter assays were performed in IB3-1 CF cells transfected with pMIR-report vectors, either controls or those containing IL-8 3′-UTR target sequences of miR-16 (both WT and mutant), in the presence of pre-miR-16 or control pre-miR. The data reflect averages of at least three independent experiments (*P<0.05 and **P>0.05).