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Proc Natl Acad Sci U S A. 2019 May 14;116(20):10009-10018. doi: 10.1073/pnas.1821442116. Epub 2019 Apr 26.

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

Author information

1
Science for Life Laboratory, KTH Royal Institute of Technology, 17165 Solna, Sweden; laura.orellana@scilifelab.se wcavenee@ucsd.edu ffurnari@ucsd.edu modesto.orozco@irbbarcelona.org.
2
Department of Biochemistry and Biophysics, Stockholm University, 11419 Stockholm, Sweden.
3
Ludwig Institute for Cancer Research, University of California, San Diego, La Jolla, CA 92093-0660.
4
Institute for Research in Biomedicine (IRB Barcelona), the Barcelona Institute of Science and Technology, 08028 Barcelona, Catalonia, Spain.
5
Department of Computational Science and Technology, KTH Royal Institute of Technology, 11428 Stockholm, Sweden.
6
Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, 2780-157 Oeiras, Portugal.
7
Centre de Biochimie Structurale (CBS), INSERM, CNRS, Université de Montpellier, 34090 Montpellier, France.
8
Olivia Newton-John Cancer Research Institute, Austin Hospital, Heidelberg, VIC 3084, Australia.
9
School of Cancer Medicine, La Trobe University, Bundoora, VIC 3086, Australia.
10
Science for Life Laboratory, KTH Royal Institute of Technology, 17165 Solna, Sweden.
11
Ludwig Institute for Cancer Research, University of California, San Diego, La Jolla, CA 92093-0660; laura.orellana@scilifelab.se wcavenee@ucsd.edu ffurnari@ucsd.edu modesto.orozco@irbbarcelona.org.
12
Institute for Research in Biomedicine (IRB Barcelona), the Barcelona Institute of Science and Technology, 08028 Barcelona, Catalonia, Spain; laura.orellana@scilifelab.se wcavenee@ucsd.edu ffurnari@ucsd.edu modesto.orozco@irbbarcelona.org.
13
Department of Biochemistry and Biomedicine, University of Barcelona, 08028 Barcelona, Catalonia, Spain.

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.

KEYWORDS:

cancer; cryptoepitope; intermediate; mutational heterogeneity; structural convergence

PMID:
31028138
PMCID:
PMC6525488
[Available on 2019-10-26]
DOI:
10.1073/pnas.1821442116

Conflict of interest statement

Conflict of interest statement: A.M.S. is an inventor on patents related to mAb806 and has received research support from Abbvie, the National Health and Medical Research Council, and the Cancer Council Victoria. A.M.S. is also a consultant with Life Science Pharmaceuticals. A.M.S., F.B.F., and W.K.C. are inventors on US Patent 9,023,356 on a treatment method using EGFR antibodies and src inhibitors in related formulations.

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