Induction of Acquired Resistance towards EGFR Inhibitor Gefitinib in a Patient-Derived Xenograft Model of Non-Small Cell Lung Cancer and Subsequent Molecular Characterization

Abstract

In up to 30% of non-small cell lung cancer (NSCLC) patients, the oncogenic driver of tumor growth is a constitutively activated epidermal growth factor receptor (EGFR). Although these patients gain great benefit from treatment with EGFR tyrosine kinase inhibitors, the development of resistance is inevitable. To model the emergence of drug resistance, an EGFR-driven, patient-derived xenograft (PDX) NSCLC model was treated continuously with Gefitinib in vivo. Over a period of more than three months, three separate clones developed and were subsequently analyzed: Whole exome sequencing and reverse phase protein arrays (RPPAs) were performed to identify the mechanism of resistance. In total, 13 genes were identified, which were mutated in all three resistant lines. Amongst them the mutations in NOMO2, ARHGEF5 and SMTNL2 were predicted as deleterious. The 53 mutated genes specific for at least two of the resistant lines were mainly involved in cell cycle activities or the Fanconi anemia pathway. On a protein level, total EGFR, total Axl, phospho-NFκB, and phospho-Stat1 were upregulated. Stat1, Stat3, MEK1/2, and NFκB displayed enhanced activation in the resistant clones determined by the phosphorylated vs. total protein ratio. In summary, we developed an NSCLC PDX line modelling possible escape mechanism under EGFR treatment. We identified three genes that have not been described before to be involved in an acquired EGFR resistance. Further functional studies are needed to decipher the underlying pathway regulation.

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“…These results indicated that genipin might directly bind to the STAT-3-SH2 domain and inhibit the dimerization of STAT-3 or STAT-1:STAT-3. EGFR can also bind to the STAT-3-SH2 domain and activate STAT-3 [27]. GST pull-down results indicated that purified STAT-3-SH2 interplayed with EGFR and genipin exposure (20 μM) suppressed the complex formation (Fig.…”

Restoration of circPSMC3 sensitizes gefitinib‐resistant esophageal squamous cell carcinoma cells to gefitinib by regulating miR‐10a‐5p/PTEN axis

“…Several studies have proved that gefitinib exerts anticancer activity in multiple types of human cancer, including non‐small cell lung cancer, and ESCC (Sasatani et al, 2019; Schueler et al, 2019; Zhang et al, 2019). But, the resistance to gefitinib treatment is a major obstacle to the effective treatment of patients with ESCC.…”

Triptolide inhibits epithelial‑mesenchymal transition and induces apoptosis in gefitinib‑resistant lung cancer cells

“…Increasing numbers of in vitro and in vivo studies have reported various possible molecular mechanisms of drug resistance to gefitinib, among which EGFR gene amplification and EMT are the most studied (28)(29)(30). Rho et al reported that EMT resulting from repeated exposure to gefitinib blunted the sensitivity of A549 cells to EGFR inhibitors (31).…”