Nrf2 orchestrates epigenetic regulation and acts as the master regulator of KLF4 expression and activity during arsenic-induced cell transformation

Emerging evidence suggests that Nrf2 plays a pro-carcinogenic role in various cancers. Our previous study showed that arsenic-induced Nrf2 activation promotes metabolic reprogramming and cancer stem-like cell formation. Here, we identify KLF4, a key pluripotency factor, as a direct transcriptional target of Nrf2 in arsenic-exposed human bronchial epithelial cells. ChIP-seq revealed multiple Nrf2 binding peaks at the KLF4 gene locus, co-localizing with the enhancer markers H3K4me1 and H3K27Ac. Nrf2 knockout reduced KLF4 expression and decreased enhancer marker enrichment, alongside a genome-wide reduction in KLF4 binding in arsenic-treated BEAS-2B cells. In BEAS-2B cells with functional Nrf2, arsenic treatment significantly increased KLF4 binding on genes involved in several oncogenic pathways, including STAT3, SOX2, Nrf2, cell growth, Hedgehog, and epithelial-to-mesenchymal transition (EMT). We also found that KLF4 participates in a self-regulating feedback loop in response to arsenic-induced Nrf2 signaling. Co-occupancy of Nrf2 and KLF4 is crucial for establishing active enhancers, suggesting that Nrf2’s oncogenic effects are, at least in part, mediated by Nrf2-dependent self-amplification of KLF4 expression and function. Thus, co-targeting Nrf2 and KLF4 may represent a promising therapeutic strategy for eliminating cancer stem-like cells.