Oncogenic mutations at the EGFR ectodomain structurally converge to remove a steric hindrance on a kinase-coupled cryptic epitope

Laura Orellana, Amy H. Thorne, Rafael Lema, Johan Gustavsson, Alison D. Parisian, Adam Hospital, Tiago N. Cordeiro, Pau Bernado, Andrew M. Scott, Isabelle Brun-Heath, Erik Lindahl, Webster K. Cavenee, Frank B. Furnari, Modesto Orozco

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Epidermal growth factor receptor (EGFR) signaling is initiated by a large ligand-favored conformational change of the extracellular domain (ECD) from a closed, self-inhibited tethered monomer, to an open untethered state, which exposes a loop required for strong dimerization and activation. In glioblastomas (GBMs), structurally heterogeneous missense and deletion mutations concentrate at the ECD for unclear reasons. We explore the conformational impact of GBM missense mutations, combining elastic network models (ENMs) with multiple molecular dynamics (MD) trajectories. Our simulations reveal that the main missense class, located at the I-II interface away from the self-inhibitory tether, can unexpectedly favor spontaneous untethering to a compact intermediate state, here validated by small-angle X-ray scattering (SAXS). Significantly, such intermediate is characterized by the rotation of a large ECD fragment (N-TR1), deleted in the most common GBM mutation, EGFRvIII, and that makes accessible a cryptic epitope characteristic of cancer cells. This observation suggested potential structural equivalence of missense and deletion ECD changes in GBMs. Corroborating this hypothesis, our FACS, in vitro, and in vivo data demonstrate that entirely different ECD variants all converge to remove N-TR1 steric hindrance from the 806-epitope, which we show is allosterically coupled to an intermediate kinase and hallmarks increased oncogenicity. Finally, the detected extraintracellular coupling allows for synergistic cotargeting of the intermediate with mAb806 and inhibitors, which is proved herein.

Original languageEnglish
Pages (from-to)10009-10018
JournalProceedings of the National Academy of Sciences of the United States of America
Volume116
Issue number20
DOIs
Publication statusPublished - 14 May 2019

Keywords

  • cancer
  • mutational heterogeneity
  • structural convergence
  • intermediate
  • cryptoepitope

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