Nrf2 and HIF1α converge to arsenic-induced metabolic reprogramming and the formation of the cancer stem-like cells
Zhuoyue Bi, Qian Zhang, Yao Fu, Priya Wadgaonkar, Wenxuan Zhang, Bandar Almutairy, Liping Xu, M’Kya Rice, Yiran Qiu, Chitra Thakur, Fei Chen
Abstract
In this report, we demonstrated that inorganic arsenic (iAs) induces generation of the cancer stem-like cells (CSCs) through Nrf2-dependent HIF1 activation, and the subsequent metabolic reprogramming from mitochondrial oxidative phosphorylation to glycolysis in epithelial cells. Methods: Genome-wide ChIP-seq analysis was performed to investigate the global binding of Nrf2 and/or HIF1 on the genome in the cells treated with iAs. Both untargeted metabolomics and UDP-13 C-glucose flux were applied to determine metabolic reprogramming in the iAs-induced CSCs. The role of Nrf2 on iAs-induced HIF1 and other stemness gene expression was validated by lentiviral transfection of Nrf2 inhibitor Keap1 and CRISPR-Cas9-mediated Nrf2 gene knockout, respectively. Results: The CSCs induced by iAs exhibit a diminished mitochondrial oxidative phosphorylation and an enhanced glycolysis that is actively shunted to the hexosamine biosynthetic pathway (HBP) and serine/glycine pathway. ChIP-seq data revealed that treatment of the cells with iAs amplified Nrf2 enrichment peaks in intergenic region, promoter and gene body. In contrast, a shift of the HIF1 peaks from distal intergenic region to gene promoter and the first exon was noted. Both Nrf2 and HIF1 are responsible for the iAs-induced expression of the glycolytic genes and the genes important for the stemness of the CSCs. Intriguingly, we also discovered a mutual transcriptional regulation between Nrf2 and HIF1. Inhibition of Nrf2 by lentiviral infection of Keap1, or knockout of Nrf2 by CRISPR-Cas9 gene editing, not only blocked iAs-induced HIF1 activation, but reduced the expression of the key stemness genes for the formation of CSCs also.