Abstract
Pancreatic ductal adenocarcinoma (PDAC) emerges from mutant KRAS-harboring but dormant low-grade pancreatic intraepithelial neoplasia (PanIN). To examine the role of oxidative stress, a putative PDAC risk factor, we established an organoid-based transformation system. Although the prototypic oxidant H2O2 induced organoid transformation, its effect was nonmutational and was mediated by the oxidant-responsive transcription factor NRF2, which induced the histone methyltransferase EZH2. Congruently, nonoxidizing NRF2 activators triggered organoid malignant conversion through NRF2 and EZH2, establishing a hitherto unknown epigenetic mechanism underlying PanIN-to-PDAC progression. While NRF2 induced EZH2 gene transcription in mouse and human PDAC, EZH2, a general repressor, coactivated transcription of NRF2-encoding NFE2L2 and interacted with other transcription factors to induce genes that sustain PDAC metabolic demands. The self-amplifying NRF2-EZH2 epigenetic loop also accounted for inflammation-driven PanIN-to-PDAC progression in vivo and was upregulated in established human PDAC, whose malignancy was maintained by NRF2 binding to the EZH2 promoter.