title: EGFR wild-type amplification and activation promote invasion and development of glioblastoma independent of angiogenesis.
abstract: Angiogenesis is regarded as a hallmark of cancer progression and it has been postulated that solid tumor growth depends on angiogenesis. At present, however, it is clear that tumor cell invasion can occur without angiogenesis, a phenomenon that is particularly evident by the infiltrative growth of malignant brain tumors, such as glioblastomas (GBMs). In these tumors, amplification or overexpression of wild-type (wt) or truncated and constitutively activated epidermal growth factor receptor (EGFR) are regarded as important events in GBM development, where the complex downstream signaling events have been implicated in tumor cell invasion, angiogenesis and proliferation. Here, we show that amplification and in particular activation of wild-type EGFR represents an underlying mechanism for non-angiogenic, invasive tumor growth. Using a clinically relevant human GBM xenograft model, we show that tumor cells with EGFR gene amplification and activation diffusely infiltrate normal brain tissue independent of angiogenesis and that transient inhibition of EGFR activity by cetuximab inhibits the invasive tumor growth. Moreover, stable, long-term expression of a dominant-negative EGFR leads to a mesenchymal to epithelial-like transition and induction of angiogenic tumor growth. Analysis of human GBM biopsies confirmed that EGFR activation correlated with invasive/non-angiogenic tumor growth. In conclusion, our results indicate that activation of wild-type EGFR promotes invasion and glioblastoma development independent of angiogenesis, whereas loss of its activity results in angiogenic tumor growth.
authors: Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway.
authors: Krishna M
authors: KM
authors: Talasila
authors: Anke
authors: A
authors: Soentgerath
authors: Philipp
authors: P
authors: Euskirchen
authors: Gro V
authors: GV
authors: Rosland
authors: Jian
authors: J
authors: Wang
authors: Peter C
authors: PC
authors: Huszthy
authors: Lars
authors: L
authors: Prestegarden
authors: Kai Ove
authors: KO
authors: Skaftnesmo
authors: Per Øystein
authors: PØ
authors: Sakariassen
authors: Eskil
authors: E
authors: Eskilsson
authors: Daniel
authors: D
authors: Stieber
authors: Olivier
authors: O
authors: Keunen
authors: Narve
authors: N
authors: Brekka
authors: Ingrid
authors: I
authors: Moen
authors: Janice M
authors: JM
authors: Nigro
authors: Olav K
authors: OK
authors: Vintermyr
authors: Morten
authors: M
authors: Lund-Johansen
authors: Simone
authors: S
authors: Niclou
authors: Sverre J
authors: SJ
authors: Mørk
authors: Per Oyvind
authors: PO
authors: Enger
authors: Rolf
authors: R
authors: Bjerkvig
authors: Hrvoje
authors: H
authors: Miletic
mesh_terms: D061067:Antibodies, Monoclonal, Humanized / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D001932:Brain Neoplasms / Q000235:genetics* / Q000473:pathology*; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D000068818:Cetuximab; D066246:ErbB Receptors / Q000187:drug effects / Q000235:genetics; D005784:Gene Amplification; D018773:Genes, erbB-1 / Q000235:genetics*; D005909:Glioblastoma / Q000235:genetics* / Q000473:pathology*; D006801:Humans; D009361:Neoplasm Invasiveness / Q000235:genetics; D009389:Neovascularization, Pathologic; D015533:Transcriptional Activation; D023041:Xenograft Model Antitumor Assays
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D066246:ErbB Receptors; D000068818:Cetuximab