title: Novel genomic alterations and mechanisms associated with tumor progression in oligodendroglioma and mixed oligoastrocytoma.
abstract: Combined 1p/19q deletions are very prevalent in oligodendrogliomas (OGs) and, to a lesser extent, in oligoastrocytomas (OAs). These losses are associated with responsiveness to therapy. Using array-based comparative genomic hybridization, we screened for recurrent genomic alterations in OG and oligoastrocytoma subtypes on chromosome 19. Concomitant 1p/19q loss was detected in most of the tumors with allelic loss, but array-based comparative genomic hybridization revealed some tumors to have unrelated 1p/19q arm losses, suggesting alternative mechanisms of loss to that related to the reported t(1;19) translocation. Analyses of 1p/19q loss by fluorescence in situ hybridization and loss of heterozygosity assays and correlations of genomic data with the Ki-67 proliferation marker were also performed. Four 1q (or 19p) and 2 1p (or 19q) fluorescence in situ hybridization probe signals together with homozygosity of the 1p/19q microsatellites suggested a hypothetical mechanism of genome duplication consecutive to the loss of the derivative chromosome der(1p;19q) from the t(1;19)(1q;19p) translocation. This genome duplication was frequent in high-grade OGs and was strongly correlated with Ki-67 expression; thus, it could be related to tumor progression. Finally, in addition to the frequent 1p/19q loss, we report a novel 17q amplified region in OGs with BIRC5 as one of the possible candidate target genes of the amplicon.
authors.affiliation: Molecular Cytogenetics Group, Madrid, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Blesa
authors.forename: Manuela
authors.initials: M
authors.lastname: Mollejo
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Ruano
authors.forename: Angel Rodríguez
authors.initials: AR
authors.lastname: de Lope
authors.forename: Concepción
authors.initials: C
authors.lastname: Fiaño
authors.forename: Teresa
authors.initials: T
authors.lastname: Ribalta
authors.forename: Juan Fernando
authors.initials: JF
authors.lastname: García
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Campos-Martín
authors.forename: Jose-Luis
authors.initials: JL
authors.lastname: Hernández-Moneo
authors.forename: Juan Cruz
authors.initials: JC
authors.lastname: Cigudosa
authors.forename: Bárbara
authors.initials: B
authors.lastname: Meléndez
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000235:genetics* / Q000401:mortality; D001932:Brain Neoplasms / Q000235:genetics* / Q000401:mortality; D002648:Child; D002675:Child, Preschool; D055028:Comparative Genomic Hybridization; D005260:Female; D018628:Gene Dosage; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D019656:Loss of Heterozygosity; D008297:Male; D008875:Middle Aged; D009837:Oligodendroglioma / Q000235:genetics* / Q000401:mortality