Abstract
Epidermal growth factor receptor EGFR major driver mutations may affect downstream molecular networks and pathways, which would influence treatment outcomes of non-small cell lung cancer (NSCLC). This study aimed to unveil profiles of mutant proteins expressed in lung adenocarcinomas of 36 patients harboring representative driver EGFR mutations (Ex19del, nine; L858R, nine; no Ex19del/L858R, 18). Surprisingly, the orthogonal partial least squares discriminant analysis performed for identified mutant proteins demonstrated the profound differences in distance among the different EGFR mutation groups, suggesting that cancer cells harboring L858R or Ex19del emerge from cellular origins different from L858R/Ex19del-negative cells. Weighted gene coexpression network analysis, together with over-representative analysis, identified 18 coexpressed modules and their eigen proteins. Pathways enriched differentially for both the L858R and Ex19del mutations included carboxylic acid metabolic process, cell cycle, developmental biology, cellular responses to stress, mitotic prophase, cell proliferation, growth, epithelial to mesenchymal transition (EMT), and immune system. The IPA causal network analysis identified the highly activated networks of PARPBP, HOXA1, and APH1 under the L858R mutation, whereas those of ASGR1, APEX1, BUB1, and MAPK10 were highly activated under the Ex19del mutation. Interestingly, the downregulated causal network of osimertinib intervention showed the highest significance in overlap p-value among most causal networks predicted under the L858R mutation. We also identified the causal network of MAPK interacting serine/threonine kinase 1/2 (MNK1/2) highly activated differentially under the L858R mutation. Tumor-suppressor AMOT, a component of the Hippo pathways, was highly inhibited commonly under both L858R and Ex19del mutations. Our results could identify disease-related protein molecular networks from the landscape of single amino acid variants. Our findings may help identify potential therapeutic targets and develop therapeutic strategies to improve patient outcomes.
Highlights
The discovery of somatic mutations in the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) [1, 2] drastically changed the therapeutic perspective of non-smallcell lung cancer (NSCLC)
mass spectrometry (MS)-based proteomic analysis was conducted for 36 formalin-fixed paraffin-embedded (FFPE) tissue specimens of lung adenocarcinoma (35 involved the acinar subtype and one involved the papillary subtype)
Outcomes of lung adenocarcinoma patients receiving EGFR tyrosine kinase inhibitors (TKIs) were reported to be affected depending on the types of EGFR gatekeeper mutation [6, 74], which are serious clinical challenges
Summary
The discovery of somatic mutations in the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) [1, 2] drastically changed the therapeutic perspective of non-smallcell lung cancer (NSCLC). Suffer from drug resistance after a year of treatment, therapeutic strategies have been challenged to improve the survival benefit of first-line treatment. The efficacy of the first- and second-generation EGFR-TKIs is limited by the result of drug resistance conferred by another mutation involving the substitution of threonine 790 with methionine (T790M) [4]. The randomized phase III AURA3 trial demonstrated that the efficacy of osimertinib was significantly greater than that of platinum therapy plus pemetrexed in patients with T790M-positive advanced NSCLC [5]. Osimertinib was recommended as first-line treatment for patients with EGFR-mutant NSCLC according to the FLAURA trial that reported significantly better PFS and OS with osimertinib than with first-generation EGFRTKIs (gefitinib or erlotinib) [6, 7]
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