title: Mutational and expression analysis of the NF1 gene argues against a role as tumor suppressor in sporadic pilocytic astrocytomas.
abstract: Children with neurofibromatosis type I (NF1) have a highly increased risk for developing optic nerve gliomas. Several lines of evidence support the notion that the NF1 gene functions as tumor suppressor in these pilocytic astrocytomas and therefore it is tempting to hypothesize that the NF1 gene plays a similar role in sporadic pilocytic astrocytomas. We searched for possible mechanisms of inactivation of the NF1 gene in pilocytic astrocytomas of different locations. Protein truncation testing (PTT) did not render indication for inactivating mutations in 10 analyzed tumors. Further, loss of heterozygosity analysis revealed maintenance of heterozygosity for 3 intragenic markers in 11 informative cases. Using a real-time PCR-based assay we showed that total NF1 transcript levels are high in pilocytic astrocytomas and that the NF1 type I and type II expression ratios in pilocytic astrocytomas are comparable to ratios in normal brain tissue and high-grade gliomas. Consequently, the data presented here argue against altered NF1 gene expression and the involvement of the NF1 gene in the tumorigenesis of sporadic pilocytic astrocytomas.
authors.affiliation: Institut für Medizinische Biologie, Universität Wien, Vienna, Austria.
authors.forename: Katharina
authors.initials: K
authors.lastname: Wimmer
authors.forename: Markus
authors.initials: M
authors.lastname: Eckart
authors.forename: Birgit
authors.initials: B
authors.lastname: Meyer-Puttlitz
authors.forename: Christa
authors.initials: C
authors.lastname: Fonatsch
authors.forename: Torsten
authors.initials: T
authors.lastname: Pietsch
mesh_terms: D000293:Adolescent; D000328:Adult; D001254:Astrocytoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D001932:Brain Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D002648:Child; D016514:Genes, Neurofibromatosis 1; D016147:Genes, Tumor Suppressor; D006801:Humans; D019656:Loss of Heterozygosity; D009154:Mutation; D025542:Neurofibromin 1 / Q000235:genetics / Q000302:isolation & purification; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000096:biosynthesis
chemical_list: D025542:Neurofibromin 1; D011994:Recombinant Proteins