Fig. 4: MiR-30a functions as tumor suppressor partly through SNAI1/IRS1/AKT/ERK pathway.

a The effect of miR-30a modulation (miR-con, miR-30a and miR-30a inhibitor) on IRS1 and SNAI1 protein expression by western blot analysis in SW1990 cells. b MiR-30a targets SNAI1 directly. Representative seed sequences for miR-30a on the SNAI1 3′UTR was shown (left). 293T cells were transiently transfected with pmirGlo plasmids encoding wild-type or mutated 3′UTR sequences of SNAI1, and oligos. Luciferase activities were then measured 24 h after transfection (right). Firefly luciferase was normalized to Renilla luciferase. The data are represented as mean ± SEM (n = 3). c–e Knockdown of SNAI1 by transfection of two different SNAI1 siRNAs (si-SNAI1–1, si -SNAI1–2) in SW1990 cells. Cell growth (c) and gemcitabine sensitivity (d) were tested by MTS assay. Downstream proteins of SNAI1 were examined by western blot (e). *P < 0.05 and **P < 0.01, compared with si-NC. f–h Indicated constructs (miR-Con, miR-30a, and/or SNAI1) were transfected in SW1990 cells. Cell growth (f) and gemcitabine sensitivity (g) were tested by MTS assay. Downstream proteins of SNAI1 were examined by western blot (h). *P < 0.05 and **P < 0.01, compared with miR-Con. ^#P < 0.05 and ^##P < 0.01, compared with miR-30a. Points, mean values for three independent experiments; error bars, ±SEM