NRF2 transcriptionally activates the promoter under oxidative stress and affects survival and migration potential of MCF7 cells.

Functional up-regulation of heat shock factor 1 (HSF1) activity through different posttranslational modifications has been implicated in the survival and proliferation of various cancers. It is increasingly recognized that the gene is also up-regulated at the transcriptional level, a phenomenon correlated with poor prognosis for patients with different cancers, including breast cancer. Here, we analyzed the transcriptional up-regulation of in human cells upon arsenite- or peroxide-induced oxidative stress. Sequential promoter truncation coupled with bioinformatics analysis revealed that this activation is mediated by two antioxidant response elements (AREs) located between 1707 and 1530 bp upstream of the transcription start site of the gene. Using shRNA-mediated down-regulation, ChIP of NRF2, site-directed mutagenesis of the AREs, and DNase I footprinting of the promoter, we confirmed that nuclear factor erythroid-derived 2-like 2 (NRF2, also known as NFE2L2) interacts with these AREs and up-regulates expression. We also found that BRM/SWI2-related gene 1 (BRG1), a catalytic subunit of SWI2/SNF2-like chromatin remodeler, is involved in this process. We further show that NRF2-dependent gene regulation plays a crucial role in cancer cell biology, as interference with NRF2-mediated activation compromised survival, migration potential, and the epithelial-to-mesenchymal transition and autophagy in MCF7 breast cancer cells exposed to oxidative stress. Taken together, our findings unravel the mechanistic basis of gene regulation in cancer cells and provide molecular evidence supporting a direct interaction between HSF1 and NRF2, critical regulators of two cytoprotective mechanisms exploited by cancer cells.