miR-21 regulates PTEN expression at the post-transcriptional level and influences the phosphorylation of AKT.

Cells were transfected with miR-21 inhibitor, inhibitor-negative control (NC) or blank control culture medium (NT). Cell lysates were obtained after 48h for analysis. (A) Correlation between miR-21 expression and PTEN protein levels in NPC tissues (Pearson correlation = −0.721). (B) Relative luciferase activity of wt or mutant reporter plasmid co-transfected into CNE1 cells with miR-21 or negative control (NC). Luciferase activity was normalized to that of the control group to obtain relative luciferase activity. pGL3-PTEN-wt represents pGL3-PTEN wild-type plasmid vector, and pGL3-PTEN-mut represents pGL3-PTEN mutant reporter plasmid vector. Data were means ± SD (n = 3). Asterisks indicate values that are significantly different from the NC group (P<0.01). (C) Expression of PTEN and phosphorylated AKT examined by Western blotting. The results were normalized to β-actin protein expression and expressed as fold change relative to the corresponding negative control. Data were means ± SD (n = 3) Asterisks indicate values that are significantly different from the NT group (P<0.01). (D) Representative immunoblots of PTEN protein expression and the levels of phosphorylated AKT after treatment with negative control and miR-21 inhibitor.