miR-21 inhibits the effects of cyclooxygenase-2 inhibitor NS398 on apoptosis and invasion in gastric cancer cells

Objective: To investigate the role of miR-21 in cyclooxygenase-2 inhibitor NS398-induced apoptosis and invasion in gastric cancer (GC) cells. Methods: AGS cells were treated with NS398 and transfected with miR-21. Quantitative real-time polymerase chain reaction was used to measure miR-21 mRNA expression. Apoptotic cells were assessed by terminal deoxynucleotidyl transferase- mediated dUTP nick end-labeling and flow cytometric analysis. The protein expression of cleaved caspase-3, Bcl-2, Bax, Bak, and PTEN was detected by Western blot. The capacities for invasion and migration were measured by transwell and wound-healing assays, respectively. Results: Treatment of AGS cells with NS398 induced apoptosis in a dose-dependent manner accompanied by significant downregulation of miR-21 mRNA expression. Upregulation of miR-21 expression by transfection of miR-21 mimics into AGS cells blocked NS398-induced apoptosis. Treatment of AGS cells with NS398 induced changes in Bcl-2 protein family members, showing an increase in the protein expression of Bax, Bak, and PTEN, with a concomitant decrease in the protein expression of Bcl-2. In cells transfected with miR-21 mimics, these changes were reversed. The decrease in cellular invasiveness and migration induced by NS398 was blocked by upregulation of miR-21. Conclusion: miR-21 mediates anticancer effects of NS398 in GC cells by regulating apoptosis-related proteins. miR-21 is one of the molecular targets of this specific cyclooxygenase-2 inhibitor in the prevention and treatment of GC.