UNLABELLED: Epidermal growth factor receptor (EGFR) is an important therapeutic target and a poor prognosis factor in head and neck squamous cell carcinoma (HNSCC). The aim of the study was to analyze EGFR expression and KRAS and EGFR mutational status and to correlate it with treatment response to anti-EGFR therapy combined with radiotherapy in 29 patients with advanced head and neck squamous cell carcinomas (HNSCC).EGFR gene expression normalized to GAPDH and EGFR variant type III (EGFRvIII) was detected in tumor tissue using real time reverse transcription -PCR. The mutational status of the EGFR and KRAS genes was investigated by real time PCR with sequence specific primers.Gene expression median values were 3.1x10(8) GAPDH gene copies per µg of RNA, and 8x10(6) EGFR gene copies per µg of RNA. The median EGFR/GADPH ratio reached 0.14. Patients, who achieved complete response after Cetuximab combined with radiotherapy, had significantly higher expression of the EGFR gene in tumors than patients with partial remission or patient without treatment response. An EGFRvIII mutation was found in 20.7 % of patients and no association was found between this mutation and treatment response. 27 patients (93.1 %) had an EGFR gene wild type tumor, and deletion in exon 19 was found in two patients with a poor clinical outcome. Most of the patients (82.8%) had a KRAS wild type tumor; a p.Gly12Cys was found in three patients and a p.Gly12Val mutation in one. Presence of a p.Gly12Val mutation in the KRAS gene was associated with an absence of response to treatment. CONCLUSION: Our data suggest that KRAS mutation (p.Gly12Val) and somatic EGFR mutation located in exon 19 may contribute to the limited clinical response to therapy with cetuximab + radiotherapy. Higher EGFR gene expression serves as an independent indicator of good clinical response to EGFR-targeted therapy + radiotherapy.

• MeSH
• cetuximab MeSH
• chemoradioterapie * MeSH
• erbB receptory antagonisté a inhibitory   genetika   MeSH
• humanizované monoklonální protilátky MeSH
• imunoenzymatické techniky MeSH
• lidé středního věku MeSH
• lidé MeSH
• míra přežití MeSH
• monoklonální protilátky terapeutické užití   MeSH
• mutace genetika   MeSH
• nádory hlavy a krku genetika   mortalita   terapie   MeSH
• následné studie MeSH
• prospektivní studie MeSH
• protinádorové látky terapeutické užití   MeSH
• protoonkogenní proteiny p21(ras) MeSH
• protoonkogenní proteiny genetika   MeSH
• Ras proteiny genetika   MeSH
• senioři MeSH
• signální transdukce genetika   MeSH
• spinocelulární karcinom genetika   mortalita   terapie   MeSH
• staging nádorů MeSH
• stupeň nádoru MeSH
• výsledek terapie MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cetuximab MeSH
• EGFR protein, human MeSH Prohlížeč
• epidermal growth factor receptor VIII MeSH Prohlížeč
• erbB receptory MeSH
• humanizované monoklonální protilátky MeSH
• KRAS protein, human MeSH Prohlížeč
• monoklonální protilátky MeSH
• protinádorové látky MeSH
• protoonkogenní proteiny p21(ras) MeSH
• protoonkogenní proteiny MeSH
• Ras proteiny MeSH

Epidermal growth factor receptor (EGFR) gene amplification and the overexpression of EGFR are described as common features of glioblastoma multiforme (GBM). Nevertheless, we previously reported the loss of EGFR gene copy in a GBM specimen from a patient with an unusually favorable course of the disease, and the HGG-02 cell line with this aberration was successfully derived from this tumor. Here, we present a detailed analysis of changes in gene expression and cell signaling in the HGG-02 cell line; the GM7 reference cell line with a standard EGFR gene copy number derived from a very aggressive GBM was used as a control. We confirmed the downregulation of EGFR expression and signaling in HGG-02 cells using different methods (RTK analysis, gene profiling and RT-PCR). Other changes that may have contributed to the non-aggressive phenotype of the primary tumor were identified, including the downregulated phosphorylation of the Axl and Trk receptors, as well as increased activity of JNK and p38 kinases. Notably, differences in PDGF signaling were detected in both of these cell lines; HGG-02 cells preferentially expressed and signaled through PDGFRα, and PDGFRβ was strongly overexpressed and phosphorylated in the GM7 reference cell line. Using expression profiling of cancer-related genes, we revealed the specific profile of HGG-02 cells that included upregulated tumor-suppressors as well as downregulated genes associated with the extracellular matrix. This study represents the first comprehensive analysis of gene expression and cell signaling in glioblastoma cells with lower EGFR gene dosage. As indicated by our results, the TAM receptors, Trk receptors and PDGFRs need to be investigated further since their regulation appears to be important for glioblastoma biological features as well as the clinical course of the disease.

• MeSH
• delece genu * MeSH
• destičkový růstový faktor metabolismus   MeSH
• erbB receptory genetika   MeSH
• fosforylace MeSH
• genová dávka * MeSH
• glioblastom genetika   MeSH
• JNK mitogenem aktivované proteinkinasy biosyntéza   MeSH
• lidé MeSH
• mitogenem aktivované proteinkinasy p38 biosyntéza   MeSH
• nádorové buněčné linie MeSH
• nádory mozku genetika   MeSH
• protoonkogenní proteiny c-sis metabolismus   MeSH
• protoonkogenní proteiny metabolismus   MeSH
• receptor trkA metabolismus   MeSH
• signální transdukce genetika   MeSH
• stanovení celkové genové exprese MeSH
• tyrosinkinasové receptory metabolismus   MeSH
• tyrozinkinasový receptor AXL MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• AXL protein, human MeSH Prohlížeč
• destičkový růstový faktor MeSH
• epidermal growth factor receptor VIII MeSH Prohlížeč
• erbB receptory MeSH
• JNK mitogenem aktivované proteinkinasy MeSH
• mitogenem aktivované proteinkinasy p38 MeSH
• platelet-derived growth factor A MeSH Prohlížeč
• protoonkogenní proteiny c-sis MeSH
• protoonkogenní proteiny MeSH
• receptor trkA MeSH
• tyrosinkinasové receptory MeSH
• tyrozinkinasový receptor AXL MeSH

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.

• Klíčová slova
• EGFR, EGFRvIII, angiogenesis, glioblastoma, invasion,
• MeSH
• analýza přežití MeSH
• erbB receptory genetika   metabolismus   MeSH
• glioblastom diagnostické zobrazování   genetika   metabolismus   patologie   MeSH
• invazivní růst nádoru MeSH
• lidé MeSH
• molekulární evoluce MeSH
• mozek diagnostické zobrazování   patologie   MeSH
• multimodální zobrazování MeSH
• mutace MeSH
• nádorové buněčné linie MeSH
• nádory mozku diagnostické zobrazování   genetika   metabolismus   patologie   MeSH
• patologická angiogeneze metabolismus   MeSH
• protoonkogenní proteiny pp60(c-src) metabolismus   MeSH
• upregulace MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• EGFR protein, human MeSH Prohlížeč
• epidermal growth factor receptor VIII MeSH Prohlížeč
• erbB receptory MeSH
• protoonkogenní proteiny pp60(c-src) MeSH