MicroRNA-143 suppresses gastric cancer cell growth and induces apoptosis by targeting COX-2

Figure 3 MicroRNA-143-5p directly inhibits cyclooxygenase-2 expression. A: Sites of miR-143-5p seed matches in the cyclooxygenase-2 (COX-2) 3′-untranslated region (3′-UTR) (nucleotides 3515-3536); B: Western blot of COX-2 protein in the MKN-1 and BGC-823 gastric cancer cell lines at 3 d after transfection with miR-143-5p, miR-143-3p or microRNA (miRNA) mimic control. GAPDH was used as a control. The results showed a profound decrease in COX-2 protein expression after transfection with miR-143-5p but not miR-143-3p; C: Real-time reverse transcription-polymerase chain reaction to determine COX-2 mRNA expression was performed 2 d after transfection with miR-143-5p, miR-143-3p or a control in MKN-1 and BGC-823. The mean expression in the control group was normalized to 1. Consistent with transcriptional inhibition by miRNA, the COX-2 mRNA level was reduced after miR-143-5p transfection (^aP < 0.05); D: Normalized activity of the wild-type COX-2 3′-UTR luciferase reporter in BGC-823 cells, 2 d after transfection with miR-143-5p, miR-143-3p or a control. The luciferase activity was significantly decreased by miR-143-5p (^bP < 0.01) but not miR-143-3p; E: Normalized activity of the mutant-type COX-2 3′-UTR luciferase reporter in BGC-823 cells, 2 d after transfection with miR-143-5p, miR-143-3p or a control. The results showed that cotransfection of the mutant reporter plasmid with miR-143-5p or miR-143-3p had no effect on luciferase activity in the transfected cells. GAPDH: Glyceraldehyde-3-phosphate dehydrogenase.