Resistance to EGFR-TKI can be mediated through multiple signaling pathways converging upon cap-dependent translation in EGFR-wild type NSCLC

Manish R Patel, Joe Jay-Dixon, Ahad A. Sadiq, Blake A Jacobson, Robert A Kratzke

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Introduction: For the majority of patients with non-small-cell lung cancer (NSCLC), response to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) is suboptimal. In models of acquired resistance to EGFR-TKI, activation of Akt phosphorylation is frequently observed. Because Akt activation results in downstream initiation of cap-dependent protein translation, we hypothesized that a strategy of targeting cap-dependent translation in combination with erlotinib might enhance therapy. Methods: NSCLC cells that are wild type for EGFR were assayed for sensitivity to erlotinib. Serum-starved NSCLC cells were assayed for EGFR signaling and downstream pathway activation by immunoblot after stimulation with epidermal growth factor. EGFR signaling and signaling mediators of cap-dependent translation were assayed by immunoblot under serum-replete conditions 24 hours after treatment with erlotinib. Finally, combination treatment with erlotinib and two different cap-dependent translation inhibitors were done to assess the effect on cell viability. Results: EGFR signaling is coupled to activation of cap-dependent translation in EGFR wild-type cells. Erlotinib inhibits EGFR phosphorylation in EGFR-TKI resistant cells, however, results in activation of downstream signaling molecules including Akt and extracellular regulated kinase, ERK 1/2, resulting in maintenance of eukaryotic initiation factor 4F (eIF4F) activation. eIF4F cap-complex formation is maintained in erlotinib-resistant cells, but not in erlotinib-sensitive cells. Finally, using an antisense oligonucleotide against eukaryotic translation initiation factor 4E and a small-molecule inhibitor to disrupt eIF4F formation, we show that cap-dependent translation inhibition can enhance sensitivity to erlotinib. Conclusion: The results of these studies support further clinical development of translation inhibitors for treatment of NSCLC in combination with erlotinib.

Original languageEnglish (US)
Pages (from-to)1142-1147
Number of pages6
JournalJournal of Thoracic Oncology
Volume8
Issue number9
DOIs
StatePublished - Sep 2013

Keywords

  • Cap-dependent translation
  • Epidermal growth factor receptor
  • Erlotinib
  • Eukaryotic translation initiation factor 4E
  • Non-small-cell lung cancer

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