Suppression of Transcription Factor Egr-1 by Curcumin

The transcription factor early growth response-1 gene product (Egr-1) is a member of the family of immediate early response genes and regulates a number of pathophysiologically relevant genes in vasculature that are involved in growth, differentiation, immune response, wound healing, and blood clotting. In the present study, we investigated the effect of curcumin, a natural plant phenolic compound known to exhibit anticarcinogenic, antioxidant, and antiinflammatory properties, on Egr-1 expression in endothelial cells and fibroblasts. Gel mobility shift assays showed that pretreatment of endothelial cells and fibroblasts with curcumin suppressed phorbol 12-myristate 13-acetate and serum-induced Egr-1 binding activity to the consensus Egr-1 binding site and also to the Egr-1 binding site present in the promoter of tissue factor gene. Western blot analysis revealed that curcumin inhibited phorbol 12-myristate 13-acetate-induced de novo synthesis of Egr-1 protein in endothelial cells. Suppression of Egr-1 protein expression in curcumin-treated cells stemmed from the suppression of Egr-1 mRNA. Northern blot analysis showed that curcumin inhibited serum and phorbol 12-myristate 13-acetate induced expression of tissue factor and urokinase-type plasminogen activator receptor mRNA in fibroblasts. Cumulatively, the data show that curcumin suppresses the induction of transcription factor Egr-1 and thereby modulates the expression of Egr-1-regulated genes in endothelial cells and fibroblasts.