Regulation of glutathione S-transferase P1-1 gene expression by NF-kappaB in tumor necrosis factor alpha-treated K562 leukemia cells

Abstract

Glutathione S-transferases (GSTs) play an important role in the protection of cells against xenobiotics and lipid hydroperoxides generated by oxidative stress. In human, the GSTP1-1 expression is commonly increased in many tumors and involved in the development of antineoplastic drug resistance. Reactive oxygen species are released at inflammation sites and oxidative stress conditions enhance the expression of genes encoding antioxidant enzymes such as GSTs. Here we investigated the regulation of the GSTP1-1 gene expression in the K562 cell line by nuclear factor κB (NF-κB) and the pro-inflammatory cytokine tumor necrosis factor alpha (TNFα). By studying GSTP1-1 mRNA expression and NF-κB/ GSTP1-1 promoter interactions, we showed the implication of NF-κB in the GSTP1-1 gene expression and we described a new specific TNFα-inducible NF-κB binding site upstream of the minimal promoter. Moreover, TNFα treatment as well as cotransfection of NF-κB signaling pathway intermediates induced an activation of the GSTP1-1 gene promoter in K562 cells. Site-directed mutagenesis of the NF-κB site strongly inhibited TNFα- and NF-κBp65-induced promoter activation. Altogether, we showed that a sequence located at −323/−314 within the GSTP1-1 promoter bound NF-κB p50/65 and p65/p65 dimers and that this κB site was involved in the regulation of the gene by TNFα.