Resveratrol‐induced ATF3 expression is mediated by EGR‐1/KLF4 interaction

Abstract

Resveratrol, a phytoalexin readily available in the diet, is reported to possess anticancer properties in colorectal cancer. However, the underlying mechanism involved is not completely understood. We investigated the affect of resveratrol on gene modulation in HCT116 cancer cells and identified activating transcription factor 3 (ATF3) as most highly induced. Resveratrol increased ATF3 expression at the mRNA and protein level. Promoter analysis revealed a major response element located within the −514 bp region in which four putative cis‐acting elements were located. Cotransfection of these factors with the −514 bp region of the ATF3 promoter pointed to the involvement of early growth response 1 (Egr‐1) and Kruppel like factor 4 (KLF4) in resveratrol induction of ATF3. Internal deletion of the Egr‐1 and KLF4 binding sites and suppression of their protein confirmed the importance of these cis‐acting elements. Specificity of these sites to the Egr‐1 and KLF4 protein was confirmed by EMSA and ChIP assays. Resveratrol increased Egr‐1 and KLF4 expression, which preceded ATF3, and further suggests their involvement in resveratrol mediated activity. Egr‐1 and KLF4 synergize to activate ATF3 and bind each other; both enhanced by resveratrol and may facilitate ATF3 transcriptional regulation by this compound. Taken together, these results provide a novel mechanism by which resveratrol induces ATF3 expression.