title: MAP kinase activity supported by BRAF (V600E) mutation rather than gene amplification is associated with ETV1 expression in melanoma brain metastases.
abstract: In primary melanoma, ETV1 transcription factor was suggested to be activated mainly by gene amplification and to promote tumor growth in cooperation with BRAF (V600E) . Aim of this study was to investigate ETV1 expression in human melanoma with a focus on brain metastases. We investigated ETV1 in 68 human melanoma brain metastases using FISH for ETV1 gene (located at chromosome 7p21) and centromere chromosome 7 and immunohistochemistry for ETV1, BRAF (V600E) , and ETV1/BRAF associated proteins pMSK1, pRSK1, pp38, pMEK1/2, MAPKAP kinase 2, CIC, HIF-1alpha and Ki-67. We further studied ETV1 copy number variations in 32 melanoma cell lines from primary and metastatic lesions using array CGH. The influence of the MAP kinase pathway activity on ETV1 mRNA and protein expression under BRAF wild-type and BRAF (V600E) conditions were determined in melanoma cell lines using qRT-PCR and Western Blot. No ETV1 high grade amplifications were observed in tissue samples, but low grade ETV1 gene amplifications were found in 7 (10.3 %) melanoma brain metastases. ETV1 protein expression in tissue samples (15 %) correlated with BRAF (V600E) status (p = 0.007) and HIF-1alpha expression (p = 0.049), but not with ETV1 gene dose. Application of the BRAF(V600E)-specific inhibitor vemurafenib and the BRAF(V6ooE/V600K)-inhibitor dabrafenib revealed predominant regulation of ETV-1 mRNA and protein via MAPK-pathway. ETV1 expression is a rare event in human melanoma and seems to be rather based on hyperactivation of MAPK signals, by BRAF (V600E) mutation, than on ETV1 gene amplification. Consequently, therapeutic inhibition of BRAF and the downstream MAPK pathway also down-regulates oncogenic ETV1 expression.
authors: Department of Neuropathology, Institute of Pathology, Ruprecht-Karls-University, Heidelberg, Germany, peter.birner@meduniwien.ac.at.
authors: Peter
authors: P
authors: Birner
authors: Anna S
authors: AS
authors: Berghoff
authors: Carina
authors: C
authors: Dinhof
authors: Christine
authors: C
authors: Pirker
authors: David
authors: D
authors: Capper
authors: Sebastian F
authors: SF
authors: Schoppmann
authors: Peter
authors: P
authors: Petzelbauer
authors: Andreas
authors: A
authors: von Deimling
authors: Walter
authors: W
authors: Berger
authors: Matthias
authors: M
authors: Preusser
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000401:mortality / Q000556:secondary*; D045744:Cell Line, Tumor; D056915:DNA Copy Number Variations; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005260:Female; D018628:Gene Dosage; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008545:Melanoma / Q000201:enzymology / Q000235:genetics* / Q000401:mortality / Q000556:secondary*; D008875:Middle Aged; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009154:Mutation; D010091:Oximes / Q000494:pharmacology; D011379:Prognosis; D016016:Proportional Hazards Models; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D048493:Proto-Oncogene Proteins B-raf / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D012878:Skin Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000401:mortality / Q000473:pathology*; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D000077484:Vemurafenib
chemical_list: D004268:DNA-Binding Proteins; C095239:ETV1 protein, human; D007093:Imidazoles; D007211:Indoles; D010091:Oximes; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D013449:Sulfonamides; D014157:Transcription Factors; D000077484:Vemurafenib; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D020928:Mitogen-Activated Protein Kinases; C561627:dabrafenib