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

BackgroundThe 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. ResultsWe 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. ConclusionsTime-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.