Oxidative Stress Converts RAS Initiated Lesions to Cancer via a Self-Amplifying NRF2-EZH2 Loop

Whether oxidative-stress increases cancer risk mutationally or epigenetically is unknown. Pancreatic ductal carcinoma (PDAC) evolves from benign, low-grade pancreatic intraepithelial neoplasia (PanIN) initiated by oncogenic KRAS. We generated 3D cultures from 6-month-old KrasG12D/PEC mice in which KRAS is activated in pancreatic epithelial cells (PEC), a time at which their pancreata harbor PanIN1-2 preneoplastic lesions, but no frank PDAC. Treating low-passage KrasG12D/PEC organoids with H2O2 or sulforaphane, both of which activate NRF2, induces malignant features defined by altered organoid shape and size and a PDAC-related gene expression signature dependent on the NRF2-EZH2 module. Most importantly, such organoids give rise to malignant PDAC upon orthotopic transplantation whereas most untreated organoids are not tumorigenic. Deep exome sequencing of untreated and H2O2 or sulforaphane treated KrasG12D/PEC organoids was performed to detect a potential treatment-specific increase in the number of mutations.