Nrf2 Drives Epigenetic Reprogramming and Acts as the Master Regulator of KLF4 Expression and Activity in Arsenic-Induced Transformation.

Emerging evidence suggests that Nrf2 plays a pro-carcinogenic role in multiple cancers. Previous studies have shown that arsenic-induced Nrf2 activation drives metabolic reprogramming, leading to the formation of cancer stem-like cells. Here, we further demonstrate that KLF4, a key pluripotency factor, is a direct transcriptional target of Nrf2 in arsenic-treated human bronchial epithelial cells (BEAS-2B). Global chromatin immunoprecipitation sequencing (ChIP-seq) revealed multiple Nrf2 binding peaks within the KLF4 locus, overlapping with the enhancer markers H3K4me1 and H3K27Ac. Nrf2 knockout diminished KLF4 expression and reduced enhancer marker enrichment, accompanied by a global decrease in KLF4 genomic occupancy in BEAS-2B cells. Additionally, arsenic exposure enhances KLF4 binding at genes implicated in oncogenic pathways, including STAT3, SOX2, Nrf2 itself, cell growth regulators, Hedgehog signaling components, and epithelial-to-mesenchymal transition (EMT) markers. Notably, we identified a self-reinforcing feedback loop between Nrf2 and KLF4 that amplifies their oncogenic effects. Finally, our data reveal that Nrf2-KLF4 co-occupancy is essential for establishing active enhancer hubs across the genome. Collectively, these findings suggest that Nrf2's oncogenic effects are, in part, mediated through the Nrf2-dependent amplification of KLF4 expression and function. Targeting both Nrf2 and KLF4 may, therefore, represent a promising therapeutic strategy to eliminate arsenic-induced cancer stem-like cells.