Selective Elimination of NRF2-Activated Cells by Competition With Neighboring Cells in the Esophageal Epithelium

A model of coexisting NRF2-activated and KEAP1-normal cells was established in the esophageal epithelium using Keap1 conditional knockout mice. NRF2-activated cells are selectively eliminated through cell competition, but loser NRF2-activated cells leave a memory for the remaining winner KEAP1-normal cells. BACKGROUND & AIMS: NF-E2-related factor 2 (NRF2) is a transcription factor that regulates cytoprotective gene expression in response to oxidative and electrophilic stresses. NRF2 activity is mainly controlled by Kelch-like ECH-associated protein 1 (KEAP1). Constitutive NRF2 acti-vation by NRF2 mutations or KEAP1 dysfunction results in a poor prognosis for esophageal squamous cell carcinoma (ESCC) through the activation of cytoprotective functions. However, the detailed contributions of NRF2 to ESCC initia-tion or promotion have not been clarified. Here, we investi-gated the fate of NRF2-activated cells in the esophageal epithelium. METHODS: We generated tamoxifen-inducible, squamous epithelium-specific Keap1 conditional knockout (Keap1-cKO) mice in which NRF2 was inducibly activated in a subset of cells at the adult stage. Histologic, quantitative reverse-transcription polymerase chain reaction, single-cell RNA-sequencing, and carcinogen experiments were conducted to analyze the Keap1-cKO esophagus. RESULTS: KEAP1-deleted/NRF2-activated cells and cells with normal NRF2 expression (KEAP1-normal cells) coexisted in the Keap1-cKO esophageal epithelium in approximately equal numbers, and NRF2-activated cells formed dysplastic lesions. NRF2-activated cells exhibited weaker attachment to the basement membrane and gradually disappeared from the epithelium. In contrast, neighboring KEAP1-normal cells exhibited accelerated proliferation and started dominating the epithelium but accumulated DNA damage that triggered carci-nogenesis upon carcinogen exposure. CONCLUSIONS: Constitutive NRF2 activation promotes the selective elimination of epithelial cells via cell competition, but this competition induces DNA damage in neighboring KEAP1-normal cells, which predisposes them to chemical-induced ESCC.

Automated summary

A model of coexisting NRF2-activated and KEAP1-normal cells was established in the esophageal epithelium using Keap1 conditional knockout mice. NRF2-activated cells are selectively eliminated through cell competition, but loser NRF2-activated cells leave a memory for the remaining winner KEAP1-normal cells.