Analysis of the fibroblastic growth factor receptor-RAS RAF MEK ERK-ETS2 brachyury signalling pathway in chordomas

• Published in: Modern pathology 2009-08, Vol.22 (8), p.996-1005
• Main Authors: Shalaby, Asem AE, Presneau, Nadege, Idowu, Bernadine D, Thompson, Lisa, Briggs, Timothy RW, Tirabosco, Roberto, Diss, Timothy C, Flanagan, Adrienne M
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Blotting, Western; Chordoma - genetics; Chordoma - metabolism; Chromatography, High Pressure Liquid; Cloning; Cytokeratin; Danio rerio; DNA Mutational Analysis; Extracellular Signal-Regulated MAP Kinases - genetics; Extracellular Signal-Regulated MAP Kinases - metabolism; Female; Fetal Proteins - genetics; Fetal Proteins - metabolism; Fibroblasts; Gene Expression; Gene Expression Profiling; Growth factors; Histopathology; Humans; Immunohistochemistry; In Situ Hybridization, Fluorescence; Kinases; Laboratory Medicine; Male; MAP Kinase Kinase Kinases - genetics; MAP Kinase Kinase Kinases - metabolism; Medicine; Medicine & Public Health; Middle Aged; Mutation; original-article; Orthopedics; Pathology; Phosphorylation; Proto-Oncogene Protein c-ets-2 - genetics; Proto-Oncogene Protein c-ets-2 - metabolism; raf Kinases - genetics; raf Kinases - metabolism; ras Proteins - genetics; ras Proteins - metabolism; Receptors, Fibroblast Growth Factor - genetics; Receptors, Fibroblast Growth Factor - metabolism; Signal Transduction - physiology; Spinal Neoplasms - genetics; Spinal Neoplasms - metabolism; T-Box Domain Proteins - genetics; T-Box Domain Proteins - metabolism; Tissue Array Analysis; Tumors; Xenopus; Young Adult
• ISSN: 0893-3952; 1530-0285
• DOI: 10.1038/modpathol.2009.63

Chordomas are rare primary malignant bone tumours that derive from notochord precursor cells and express brachyury, a molecule involved in notochord development. Little is known about the genetic events responsible for driving the growth of this tumour, but it is well established that brachyury is regulated through fibroblastic growth factor receptors (FGFRs) through RAS/RAF/MEK/ERK and ETS2 in ascidian, Xenopus and zebrafish, although little is known about its regulation in mammals. The aim of this study was to attempt to identify the molecular genetic events that are responsible for the pathogenesis of chordomas with particular focus on the FGFR signalling pathway on the basis of the evidence in the ascidian and Xenopus models that the expression of brachyury requires the activation of this pathway. Immunohistochemistry showed that 47 of 50 chordomas (94%) expressed at least one of the FGFRs, and western blotting showed phosphorylation of fibroblast growth factor receptor substrate 2 alpha (FRS2 α ), an adaptor signalling protein, that links FGFR to the RAS/RAF/MEK/ERK pathway. Screening for mutations in brachyury (all coding exons and promoter), FGFRs 1–4 (previously reported mutations), KRAS (codons 12, 13, 51, 61) and BRAF (exons 11 and 15) failed to show any genetic alterations in 23 chordomas. Fluorescent in situ hybridisation analysis on FGFR4 , ETS2 and brachyury failed to show either amplification of these genes, although there was minor allelic gain in brachyury in three tumours, or translocation for ERG and ETS2 loci. The key genetic events responsible for the initiation and progression of chordomas remain to be discovered.