Etiology and Pathogenesis > Tumorigenesis

Abstract

Epidermal Growth Factor Receptor Activation in Glioblastoma through Novel Missense Mutations in the Extracellular Domain

Jeffrey C. Lee^1,2,3, Igor Vivanco⁴, Rameen Beroukhim^1,3,5, Julie H. Y. Huang⁶, Whei L. Feng^1,3, Ralph M. DeBiasi^1,3, Koji Yoshimoto⁷, Jennifer C. King⁸, Phioanh Nghiemphu⁹, Yuki Yuza¹, Qing Xu^1,5, Heidi Greulich^1,3,5, Roman K. Thomas^1,3, J. Guillermo Paez^1,3,5, Timothy C. Peck^1,3, David J. Linhart^1,3, Karen A. Glatt¹, Gad Getz³, Robert Onofrio³, Liuda Ziaugra³, Ross L. Levine^1,10, Stacey Gabriel³, Tomohiro Kawaguchi¹¹, Keith O'Neill³, Haumith Khan¹², Linda M. Liau¹², Stanley F. Nelson⁶, P. Nagesh Rao⁷, Paul Mischel⁷, Russell O. Pieper¹¹, Tim Cloughesy⁹, Daniel J. Leahy^13,14, William R. Sellers^1,3,5, Charles L. Sawyers^4,8,15, Matthew Meyerson^1,2,3*, Ingo K. Mellinghoff^4,8*

¹Department of Medical Oncology and Center for Cancer Genome Discovery, Dana-Farber Cancer Institute Harvard Medical School, Boston, Massachusetts, United States of America, ²Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America, ³Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America, ⁴Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America, ⁵Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America, ⁶Department of Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America, ⁷Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America, ⁸Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America, ⁹Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America, ¹⁰Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, United States of America, ¹¹Department of Neurosurgery, University of California San Francisco, San Francisco, California, United States of America, ¹²Department of Neurosurgery, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America, ¹³Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America, ¹⁴Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America, ¹⁵Howard Hughes Medical Institute, University of California Los Angeles, Los Angeles, California, United States of America.
*To whom correspondence should be addressed. E-mail: matthew_meyerson@dfci.harvard.edu (MM); imellinghoff@mednet.ucla.edu (IKM)
Received: March 20, 2006; Accepted: September 26, 2006; Published: December 19, 2006

Background. Protein tyrosine kinases are important regulators of cellular homeostasis with tightly controlled catalytic activity. 
Mutations in kinase-encoding genes can relieve the autoinhibitory constraints on kinase activity, can promote malignant transformation, and appear to be a major determinant of response to kinase inhibitor therapy. 
Missense mutations in the EGFR kinase domain, for example, have recently been identified in patients who showed clinical responses to EGFR kinase inhibitor therapy.

Methods and Findings. Encouraged by the promising clinical activity of epidermal growth factor receptor (EGFR) kinase inhibitors in treating glioblastoma in humans, we have sequenced the complete EGFR coding sequence in glioma tumor samples and cell lines. 
We identified novel missense mutations in the extracellular domain of EGFR in 13.6% (18/132) of glioblastomas and 12.5% (1/8) of glioblastoma cell lines. 
These EGFR mutations were associated with increased EGFR gene dosage and conferred anchorage-independent growth and tumorigenicity to NIH-3T3 cells.
Cells transformed by expression of these EGFR mutants were sensitive to small-molecule EGFR kinase inhibitors.

Conclusions. Our results suggest extracellular missense mutations as a novel mechanism for oncogenic EGFR activation and may help identify patients who can benefit from EGFR kinase inhibitors for treatment of glioblastoma.

Abbreviations: EGF, epidermal growth factor; EGFR, epidermal growth factor receptor; FISH, fluorescence in situ hybridization; IL-3, interleukin-3; MALDI-TOF, matrix-assisted laser desorption/ionization time-of-flight; SNP, single-nucleotide polymorphism