Effects of inhibitor of COX-2 on the expression of cyclooxygenase-2 by transforming growth factor β and Smad signaling pathway in cultured rat mesangial cells

Objective: To investigate the effects of inhibitor of COX-2 on the expression of cyclooxygenase-2 by transform- ing growth factor β and Smad signaling pathway in cultured rat mesangial cells. Methods: Using the quart glomerular mesan- gial cell for experimentation, to observe the effect of different concentrations of TGF-β on the expression of COX-2 and Smad2 mRNA at 4, 12 and 24 hours, and the effect of the inhibitor of COX-2 NS-398 on the expression of COX-2 and Smad2 mRNA. The expression of COX -2 mRNA and Smad2 mRNA was determined by RT -PCR. Results: After the glomerular mesangial cell was irritated by TGF-β, the expression of COX-2 mRNA and Smad2 mRNA increased. This de- pended on the density of TGF-β and the length of TGF-β acting time. After NS-398 (inhibitor of COX-2) was added, the expression of COX-2 mRNA and Smad2 mRNA reduced, which depended on the length of NS-398 acting time. Conclusion: One of the signaling pathways through which TGF-β increases the expression of COX-2 is the Smad signaling pathway. NS- 398 restraining the expression of cyclooxygenase-2 may be related with TGF-β/ Smad signaling pathway.