Effects Of All-Trans Retinoic Acid On Expression Of COX-2 And Smad3,Smad7 Signaling Pathway In Rat Glomerular Mesangial Cell Induced By Transforming Growth Factor-β

Objective: To investigate the effects of all-trans retinoic acid (ATRA) on the protein expression of COX-2 and Smad3, Smad7 induced by transforming growth factor-βin mesangial cells, and discuss the effect of TGF-β/Smad signaling pathway on the expression of COX-2 in rat mesangial cells cultured in vitro, and ATRA on the expression of COX-2 through TGF-β/Smad signaling pathway, which may provide a theoretical basis for the use of ATRA in kidney disease areas.Methods: Glomerular mesangial cells were randomly divided into 5 groups: (1) the control group; (2) TGF-β(5, 10ng/ml) group; (3) TGF-β+NS398 group (10μmol/L NS398+10ng/mLTGF-β); (4) TGF-β+ Stauro- sporine group (5nmol/mL Staurosporine+10ng/mL TGF-β); (5) drug gro- up: the mesangial cells were pre-treated with ATRA (the ultimate concentration were 10-3, 10-6, 10-9mol/L) for 24h, then stimulated with TGF-β(10ng/ml) for different periods (4, 12, 24h). The protein expres- sion level of COX-2 and Smad3, 7 were determined by Western blot analysis.Results: 1. Expressions of COX-2 and Smad3, 7 were increased by stimulation of exogenous TGF-β. 1h after the stimulation, the expression of COX-2 began to increase and rise to maximum at 24th hour since stimulation, but the expression of Smad3, 7 began to increase significant- ly after 1h and reached maximum between 12-24h. Compared with the control group, each group had a significant difference in both dose and time-dependent ways (P< 0.05).2. Under inducing by exogenous TGF-β(5ng/mL and 10ng/mL), the protein expression of COX-2 increased. After treated with NS-398 (inhibitor of COX-2) and Staurosporine (inhibitor of Smad) respectively, the expression of COX-2 showed a dose and time-dependent reduction (P<0.05).3. Under inducing by exogenous TGF-β(5ng/mL and 10ng/mL), the expression of Smad3, 7 protein were increased by stimulation of exogenous TGF-β(5ng/mL and 10ng/mL) but inhibited with dose and time-dependence by treatment with NS-398 (inhibitor of COX-2) and Staurosporine (inhibitor of Smad) respectively, the expression of Smad3, 7 reduced with dose and time-dependence (P<0.05).4. After pre-treated with ATRA (10-3, 10-6, 10-9 mol/L) for 24h, added TGF-βstimulated different times (4, 12, 24h), The results showed that the protein expression of COX-2, Smad3, 7 in both drug groups and TGF-βgroups were significantly reduced with dose and time-dependence (P< 0.05).5. The protein expression of COX-2 has a positive correlation with the protein expression of Smad3(P<0.05), the protein expression of COX-2 has a positive correlation with the protein expression of Smad7(P<0.05).Conclusion: 1. TGF-βcould make the protein expression of COX-2 increase in a time and dose manner in the glomerular mesangial cells.2. TGF-βcould make the protein expression of Smad3 increase in a time and dose manner in the glomerular mesangial cells.3. TGF-βcould make the protein expression of Smad7 increase in a time and dose manner in the glomerular mesangial cells.4. TGF-βcould make the protein expression of COX-2 and Smad3, 7 increase, which could be inhibited by NS-398 and Staurosporine in a time manner.5. ATRA could inhibit the protein expression of COX-2 resulted from TGF-βwith dose dependence in the mesangial cells.6. ATRA could inhibit the protein expression of Smad3 resulted from TGF-βwith dose dependence in the mesangial cells.7. ATRA could inhibit the protein expression of Smad7 resulted from TGF-βwith dose dependence in the mesangial cells.8. ATRA might inhibit the expression of COX-2 via the TGF-β/Smad signaling pathway possibly, which may play an important role in inhibiting fibrosis and cell proliferation of ATRA...