Resveratrol inhibits collagen Ⅰ synthesis by suppressing IGF-1R activation in intestinal fibroblasts

AIM:To investigate whether resveratrol(3,4,5-trihydroxy-trans-stilbene)inhibits collagenⅠsynthesis induced by insulin growth factor-1(IGF-1)in intestinal fibroblasts,and to explore the possible molecular mechanisms.METHODS:Male Sprague-Dawley rats were randomly divided into two groups:a control group and a2,4,6-trinitrobenzenesulfonic acid(TNBS)-induced colitis group.After 21 d of TNBS administration,the degree of inflammation and fibrosis in colon was measured by HE staining and Masson’s trichrome staining.Western blotting was used to examine collagenⅠ,IGF-1 and silent information regulator 1(SIRT1)protein expression in colitis tissues.Western blotting and quantitative realtime polymerase chain reaction were used to characterize collagenⅠprotein and col1a2 mRNA expression in mouse intestinal fibroblasts and CCD-18Co cells treated with IGF-1.A MEK inhibitor(U0126)was used to determine whether IGF-1-induced collagenⅠexpression was mediated by extracellular signal-regulated kinase 1/2(ERK1/2)-dependent mechanism.Effects of resveratrol on collagenⅠprotein level,insulin growth factor-1receptor(IGF-1R)and ERK1/2 phosphorylation levels were also examined after IGF-1 treatment in fibroblasts.To evaluate whether SIRT1 was necessary for the anti-fibrosis effect of resveratrol,cells were transfected with SIRT1-specific small interfering RNAs,wildtype SIRT1,and deacetylase-inactive mutant SIRT1.RESULTS:CollagenⅠand IGF-1 expression was increased,and SIRT1 expression was decreased(0.67±0.04 vs 1.05±0.07,P<0.001)in TNBS-induced colitis compared with the control group.In vitro,IGF-1 could induce collagenⅠexpression,mainly through the ERK1/2 signal pathway.Resveratrol reduced basal and IGF-1-induced collagenⅠ?gene and protein expression in intestinal fibroblasts.Overexpression of wild-type SIRT1,not deacetylase-inactive mutant SIRT1,decreased expression of collagenⅠinduced by IGF-1.Moreover,silencing SIRT1 restored collagen?Ⅰ?expression in fibroblasts challenged with resveratrol.However,disruption of SIRT1 did not influence the anti-fibrotic effects of resveratrol and IGF-1-induced collagenⅠexpression.Further analysis revealed that resveratrol significantly decreased phosphorylation of IGF-1R and its downstream signaling molecules by inhibiting IGF-1 binding to its receptor.CONCLUSION:Our data suggest that resveratrol effectively inhibits collagenⅠsynthesis in IGF-1-stimulated fibroblasts,partly by inhibiting IGF-1R activation,and SIRT1 is also responsible for the process.