Hypothesis

Early activation of nucleolar stress pathways alters ribosomal RNA synthesis and translational capacity, creating a permissive state for bypass signaling and metabolic rewiring that leads to osimertinib resistance in EGFR‑mutant NSCLC.

Mechanistic Rationale

• Multi‑omics studies show that resistance emerges from concurrent genomic, transcriptomic, proteomic, and metabolomic aberrations [1][2]
• However, the initiating event often lies upstream of these layers, in the regulation of protein synthesis.
• Nucleolar stress, sensed via changes in nucleolar phosphoproteins such as NPM1 and fibrillarin, can globally shift translational efficiency without altering mRNA levels, a layer invisible to standard RNA‑seq but detectable by ribosome profiling and phosphoproteomics [3]
• We propose that osimertinib treatment triggers nucleolar stress, leading to preferential translation of mRNAs encoding MET, AXL, and HIF‑1α, thereby activating bypass pathways and glycolysis before detectable DNA amplification or metabolic shifts appear.
• This model extends the current view by placing translational control as the early driver that later manifests as genomic copy‑number changes and metabolic re‑programming observed in longitudinal multi‑omics.

Experimental Design

1. Model system – Generate patient‑derived EGFR‑mutant NSCLC organoids and matching xenografts.
2. Longitudinal sampling – Treat with osimertinib and collect samples at 0, 24, 72 h, 1 wk, 2 wk, and at clinical progression.
3. Multi‑omics layers –
   • Ribosome profiling (Ribo‑Seq) to quantify translatome.
   • Phosphoproteomics focusing on nucleolar proteins (NPM1 T199, fibrillarin S58).
   • Targeted proteomics for MET, AXL, HIF‑1α.
   • Untargeted metabolomics for glycolytic intermediates.
   • Whole‑genome sequencing for copy‑number alterations.
4. Intervention arms –
   • Control (osimertinib alone).
   • Osimertinib + CX‑5461 (RNA polymerase I inhibitor) to blunt nucleolar stress.
   • Osimertinib + siRNA against NPM1.
5. Readouts – Tumor volume, time to progression, and molecular readouts at each time point.

Predicted Outcomes

• In the control arm, nucleolar phosphoprotein changes will appear within 24 h, followed by increased translation of MET/AXL/HIF‑1α mRNAs at 72 h, preceding detectable MET amplification (≈1 wk) and lactate accumulation (≈2 wk).
• In the CX‑5461 or NPM1‑siRNA arms, early nucleolar stress markers will be blunted, translational upregulation of bypass drivers will be reduced, and MET amplification and glycolytic shift will be delayed or absent, resulting in prolonged tumor control.
• If nucleolar stress does not precede translational changes, the hypothesis is falsified.

Potential Impact

Validating this mechanism would reveal a druggable upstream node—nucleolar transcription—that can be targeted with existing agents to prevent or delay resistance, shifting the paradigm from reactive biomarker detection to preemptive intervention grounded in translatome dynamics.