Objective To investigate the effect of curcumin on the
expression of
connective tissue growth factor(CTGF) in rat glomerular
mesangial cells and the potential mechanisms.Methods Growth arrested and synchronized rat mesangial cells were stimulated by serum.The mesangial cells were pretreated with curcumin,curcumin combined with rapamycin,or curcumin combined with PI3K/Akt specific inhibitor LY294002.The
expression of CTGF and fibronectin(Fn) mRNA in mesangial cells was detected by semi-quantitative RT-PCR,and that of CTGF protein and phospho-Akt protein by Western blot.(Results)After the cells were exposed to bovine calf serum for 6 h,curcumin could down-regulate the mRNA expression of CTGF and Fn in a dose dependent manner as compared with the control group.Curcumin combined with rapamycin could down-regulate the mRNA expression of CTGF and Fn more obviously than curcumin alone with the same concentration.After the cells were pretreated with LY294002,the inhibitory effects of curcumin on the expression of CTGF and Fn mRNA were weakened.After the cells were treated with 25 μmol/L curcumin for 30 and 120 min,the expression of p-Akt protein was decreased as compared with the control group at the same time,and the inhibitory effects of curcumin were also weakened by LY294002 pre-treatment.After the cells were exposed to bovine calf serum for 24 h,the protein expression of CTGF in curcumin treatment group was reduced as compared with the control group,and in curcumin combined with rapamycin group,the expression of CTGF protein was inhibited more markedly.After the cells were pretreated with LY294002,the phospho-Akt protein expression was detected,and curcumin down-regulated the CTGF protein expression more weakly than in no-LY294002 pretreatment group.Conclusion Curcumin can inhibit the expression of CTGF in serum-induced glomerular mesangial cells,which might be related to PI3K/Akt signal pathway and mammal target of rapamycin signal pathway.