Pyrimethamine inhibits mutant NRF2 as a molecular glue
Bibliographic record
Abstract
Abstract Esophageal squamous cell carcinoma (ESCC) is a deadly disease and one of the most aggressive cancers of the gastrointestinal tract. As a master transcription factor regulating the stress response, nuclear factor erythroid 2-related factor 2 (NRF2) is often mutated, loses negative regulation by Kelch-like ECH-associated protein 1 (KEAP1), becomes hyperactive, and thus causes chemo-radioresistance and poor survival in human ESCC. Our previous research identified pyrimethamine (PYR) as an NRF2 inhibitor and demonstrated that inhibition of dihydrofolate reductase (DHFR) is the major mechanism of its action. Based on these findings, PYR has advanced into a Phase I window-of-opportunity clinical trial. In this study, using isogenic ESCC cell lines, we aimed to investigate the phenotypic consequences of NRF2 activation in ESCC cells and further elucidate the mechanism of action of PYR. While overexpression of wild-type NRF2 (NRF2 WT ) promoted squamous differentiation and suppressed proliferation, expression of mutant NRF2 (NRF2 Mut ) produced mixed effects on differentiation markers and promoted proliferation. NRF2 activation reduced sensitivity to chemotherapy and radiation, whereas PYR treatment restored chemosensitivity and radiosensitivity in NRF2 Mut ESCC cells. Co-immunoprecipitation and proximity ligation assays revealed that PYR selectively enhanced the interaction between NRF2 W24C and KEAP1, but not between NRF2 WT and KEAP1. Isothermal titration calorimetry (ITC) confirmed the direct binding of PYR to KEAP1 and surface plasmon resonance (SPR) showed that PYR modestly facilitated the interaction between a DLG W24C peptide and the Kelch fragment. Molecular docking suggested that PYR bound to a pocket within the Kelch domain near Arg 415 . In summary, NRF2 activation promotes cell proliferation and therapy resistance in ESCC in a context-dependent manner. PYR functions as a modest molecular glue that selectively restores KEAP1 binding to NRF2 W24C , providing a potential therapeutic strategy for NRF2 Mut ESCC.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".