Time-Resolved Phosphoproteomics-Guided BFS Beam Search Reveals Cell-Type-Specific EGFR Signaling Architectures and SHP2 Inhibitor-Induced Pathway Rewiring

Abstract Background The epidermal growth factor receptor (EGFR) orchestrates highly context-dependent intracellular signaling networks whose architecture varies across cell types and is frequently rewired by targeted therapeutics. Systems-level reconstruction of these networks from phosphoproteomic data remains challenging because phosphorylation measurements identify signaling nodes but do not reveal the interaction paths that propagate signals between proteins. Results We developed a computational framework integrating time-resolved phosphoproteomics with graph traversal algorithms to reconstruct EGFR-initiated signaling pathways across three contexts/conditions. A sign-assignment preprocessing procedure converts quantitative phosphorylation measurements into binary activation states across time points, defining a condition-specific active node set that filters the protein–protein interaction network. Breadth-First Search combined with interaction-weighted Beam Search is then applied to the STRING interaction database (v11.5) to enumerate candidate signaling paths. Applying this framework to phosphoproteomic datasets from EGF-stimulated HeLa cells, EGF-stimulated MDA-MB-468 triple-negative breast cancer (TNBC) cells, and EGF-stimulated MDA-MB-468 cells pretreated with the SHP2 inhibitor SHP099 yielded 260 paths in HeLa cells (117 unique topologies), 293 paths in MDA-MB-468 cells (155 unique), and 292 paths under SHP2 inhibition (85 unique). HeLa cells displayed a SRC-centered architecture dominated by ERBB2 and SHC1 first-hop effectors, converging on focal adhesion, HSP90 chaperone, CRKL adaptor, and integrin signaling arms. In contrast, MDA-MB-468 cells showed a PIK3CA/PTPN11 dual-axis architecture integrating direct PI3K engagement with SHP2-mediated GRB2–IRS1–ABL1 signaling. SHP2 inhibition abolished PTPN11-mediated pathways and induced PIK3CA dominance (69.2% first-hop), accompanied by compensatory ERBB3 engagement and a computationally predicted SYK/VAV1/LCP2 node set whose biological role warrants experimental validation. Conclusions Time-resolved phosphoproteomics-guided BFS Beam Search over STRING interaction networks captures cell-type-specific EGFR signaling architectures and drug-induced pathway rewiring. This framework provides a systematic approach for transforming phosphoproteomic measurements into mechanistically interpretable signaling hypotheses specific to the cell-type-specific contexts, directly applicable to drug resistance modeling.