Fig. 2

miR-338-3p directly targets SphK2. SphK2 protein expressions were measured by Western blot; Blank, untransfected cells; NC, cells transfected with negative control; GAPDH served as an endogenous reference. Luciferase reporter assays were used to assess the effect of miR-338-3p on SphK2; NC, cells transfected with negative control. a The putative wild-type SphK2 3′-UTR binding sequences in miR-338-3p, and the mutation sequence of SphK2 3′-UTR was not matched with the miR-338-3p. b Western blot quantification of SphK2 expression in transfected cells. GAPDH was an endogenous reference. miR-338-3p significantly downregulated expression of SphK2 in A549 and H1299 cells. c Luciferase reporter vectors that contained wild-type (or mutant-type) 3′-UTR segments of SphK2 were constructed and co-transfected into A549 cells with NC or miR-338-3p. Co-transfection of miR-338-3p significantly decreased luciferase activity of the reporter containing pmirGLO-wt 3′-UTR (*p < 0.05), but did not decrease that of the pmirGLO-mut 3′-UTR reporter. d Luciferase reporter vectors that contained wild-type (or mutant-type) 3′-UTR segments of SphK2 were constructed and co-transfected into H1299 cells together with NC or miR-338-3p. Co-transfection of miR-338-3p significantly decreased luciferase activity of the reporter containing pmirGLO-wt 3′-UTR (*p < 0.05), but did not decrease that of the pmirGLO-mut 3′-UTR reporter