Chronic activation of wild-type epidermal growth factor receptor and loss of Cdkn2a cause mouse glioblastoma formation.

Abstract

Glioblastoma multiforme (GBM) is characterized by overexpression of epidermal growth factor receptor (EGFR) and loss of the tumor suppressors Ink4a/Arf. Efforts at modeling GBM using wild-type EGFR in mice have proven unsuccessful. Here, we present a unique mouse model of wild-type EGFR-driven gliomagenesis. We used a combination of somatic conditional overexpression and ligand-mediated chronic activation of EGFR in cooperation with Ink4a/Arf loss in the central nervous system of adult mice to generate tumors with the histopathologic and molecular characteristics of human GBMs. Sustained, ligand-mediated activation of EGFR was necessary for gliomagenesis, functionally substantiating the clinical observation that EGFR-positive GBMs from patients express EGFR ligands. To gain a better understanding of the clinically disappointing EGFR-targeted therapies for GBM, we investigated the molecular responses to EGFR tyrosine kinase inhibitor (TKI) treatment in this model. Gefitinib treatment of primary GBM cells resulted in a robust apoptotic response, partially conveyed by mitogen-activated protein kinase (MAPK) signaling attenuation and accompanied by BIM(EL) expression. In human GBMs, loss-of-function mutations in the tumor suppressor PTEN are a common occurrence. Elimination of PTEN expression in GBM cells posttumor formation did not confer resistance to TKI treatment, showing that PTEN status in our model is not predictive. Together, these findings offer important mechanistic insights into the genetic determinants of EGFR gliomagenesis and sensitivity to TKIs and provide a robust discovery platform to better understand the molecular events that are associated with predictive markers of TKI therapy.

• Authors: Jaime Acquaviva, Hyun Jung Jun, Julie Lessard, Rolando Ruiz, Haihao Zhu, Melissa Donovan, Steve Woolfenden, Abraham Boskovitz, Ami Raval, Roderick T Bronson, Rolf Pfannl, Charles A Whittaker, David E Housman, Al Charest
• Journal: Cancer research (Cancer Res) Vol. 71 Issue 23 Pg. 7198-206 (Dec 01 2011) ISSN: 1538-7445 [Electronic] United States
• PMID: 21987724 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Apoptosis Regulatory Proteins
• BCL2L11 protein, human
• Bcl-2-Like Protein 11
• Bcl2l11 protein, mouse
• Cdkn2a protein, mouse
• Cyclin-Dependent Kinase Inhibitor p16
• Ligands
• Membrane Proteins
• Protein Kinase Inhibitors
• Proto-Oncogene Proteins
• Quinazolines
• Phosphatidylinositol 3-Kinases
• ErbB Receptors
• Proto-Oncogene Proteins c-akt
• Mitogen-Activated Protein Kinase Kinases
• PTEN Phosphohydrolase
• PTEN protein, human
• Gefitinib

Topics

• Animals
• Apoptosis (drug effects, genetics)
• Apoptosis Regulatory Proteins (genetics)
• Bcl-2-Like Protein 11
• Brain Neoplasms (drug therapy, genetics, metabolism, pathology)
• Cyclin-Dependent Kinase Inhibitor p16 (deficiency, genetics)
• Enzyme Activation
• ErbB Receptors (genetics, metabolism)
• Gefitinib
• Gene Expression Regulation, Neoplastic (drug effects)
• Glioblastoma (drug therapy, genetics, metabolism, pathology)
• Humans
• Ligands
• Membrane Proteins (genetics)
• Mice
• Mitogen-Activated Protein Kinase Kinases (metabolism)
• PTEN Phosphohydrolase (genetics)
• Phosphatidylinositol 3-Kinases (metabolism)
• Protein Kinase Inhibitors (pharmacology)
• Proto-Oncogene Proteins (genetics)
• Proto-Oncogene Proteins c-akt (metabolism)
• Quinazolines (pharmacology)
• Signal Transduction (drug effects)