NRF2 Is a Potential Modulator of Hyperresistance to Arsenic Toxicity in Stem-Like Keratinocytes.
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ABSTRACT:
SUBMITTER: Wu X
PROVIDER: S-EPMC5610874 | biostudies-literature | 2017
REPOSITORIES: biostudies-literature
Publications
NRF2 Is a Potential Modulator of Hyperresistance to Arsenic Toxicity in Stem-Like Keratinocytes.
Wu Xiafang X Yang Bei B Hu Yuxin Y Sun Ru R Wang Huihui H Fu Jingqi J Hou Yongyong Y Pi Jingbo J Xu Yuanyuan Y
Oxidative medicine and cellular longevity 20170910
Arsenic is a well-known human carcinogen. Stem cells are indicated to be involved in arsenic carcinogenesis and have a survival selection advantage during arsenic exposure with underlying mechanisms undefined. In the present study, we demonstrated that CD34<sup>high</sup>-enriched cells derived from HaCaT human keratinocytes showed stem-like phenotypes. These cells were more resistant to arsenic toxicity and had higher arsenic efflux ability than their mature compartments. The master transcripti ...[more]
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Project description: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-13C-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. Conclusion: We demonstrated that Nrf2 activation is an initiating signal for iAs-induced HIF1? activation, and Nrf2 and HIF1? played a concerted role on inducing metabolic reprogramming and the CSCs.
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Project description:Exposure to arsenic, a ubiquitous metalloid on Earth, results in human cancers. Skin cancer is the most common arsenical cancers. Both autophagy and aquaporin pathway are known to promote carcinogenesis. However, the mechanisms by which arsenic regulates aquaporin and autophagy in arsenical skin cancers remain elusive. This study aims to address how arsenic regulates aquaporin-3, the predominant aquaporin in epidermal keratinocytes, and how this process would induce autophagy. Quantitative real-time PCR and immunofluorescence were used to measure the expression of aquaporin 3 in arsenical skin cancers and arsenic-treated keratinocytes. Beclin-1 expression and autophagy were measured. We examined if blocking aquaporin 3 could interfere arsenic-induced autophagy in keratinocytes. Expression of aquaporin 3 is increased in arsenical cancers and in arsenic-treated keratinocytes. Arsenic induced autophagy in primary human keratinocytes. Notably, the arsenic-induced autophagy was inhibited by pretreatment of keratinocytes with aquaporin inhibitors Auphen or AgNO3, or RNA interference against aquaporin 3. The data indicates that the aquaporin 3 is an important cell membrane channel to mediate arsenic uptake and contributes to the arsenic-induced autophagy.
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