BACKGROUND: Amplification of the epidermal growth factor receptor (EGFR) and its mutant EGFRvIII are among the most common genetic alterations in glioblastoma (GBM), the most frequent and most aggressive primary brain tumor. METHODS: In the present work, we analyzed the clonal evolution of these major EGFR aberrations in a small cohort of GBM patients using a unique surgical multisampling technique. Furthermore, we overexpressed both receptors separately and together in 2 patient-derived GBM stem cell lines (GSCs) to analyze their functions in vivo in orthotopic xenograft models. RESULTS: In human GBM biopsies, we identified EGFR amplification as an early event because EGFRvIII mutations emerge from intratumoral heterogeneity later in tumor development. To investigate the biological relevance of this distinct developmental pattern, we established experimental model systems. In these models, EGFR(+) tumor cells showed activation of classical downstream signaling pathways upon EGF stimulation and displayed enhanced invasive growth without evidence of angiogenesis in vivo. In contrast, EGFRvIII(+) tumors were driven by activation of the prototypical Src family kinase c-Src that promoted VEGF secretion leading to angiogenic tumor growth. CONCLUSIONS: The presented work shows that sequential EGFR amplification and EGFRvIII mutations might represent concerted evolutionary events that drive the aggressive nature of GBM by promoting invasion and angiogenesis via distinct signaling pathways. In particular, c-SRC may be an attractive therapeutic target for tumors harboring EGFRvIII as we identified this protein specifically mediating angiogenic tumor growth downstream of EGFRvIII.

• MeSH
• Survival Analysis MeSH
• ErbB Receptors genetics   metabolism   MeSH
• Glioblastoma diagnostic imaging   genetics   metabolism   pathology   MeSH
• Neoplasm Invasiveness MeSH
• Humans MeSH
• Evolution, Molecular MeSH
• Brain diagnostic imaging   pathology   MeSH
• Multimodal Imaging MeSH
• Mutation MeSH
• Cell Line, Tumor MeSH
• Brain Neoplasms diagnostic imaging   genetics   metabolism   pathology   MeSH
• Neovascularization, Pathologic metabolism   MeSH
• Proto-Oncogene Proteins pp60(c-src) metabolism   MeSH
• Up-Regulation MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH

• MeSH
• Phosphotyrosine metabolism   MeSH
• Chickens MeSH
• Models, Molecular MeSH
• Oncogene Protein pp60(v-src) genetics   chemistry   metabolism   MeSH
• Proto-Oncogene Proteins pp60(c-src) chemistry   metabolism   MeSH
• Saccharomyces cerevisiae genetics   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH