title: Nuclear localization and mutation of beta-catenin in medulloblastomas.
abstract: The adenomatous polyposis coli (APC) gene, a member of the Wingless/Wnt signal transduction pathway, has been implicated in the development of medulloblastomas in Turcot's syndrome. beta-catenin also functions in this highly conserved signaling pathway and is instrumental in growth and development. Mutations in either APC or beta-catenin can stabilize beta-catenin protein. Stabilized beta-catenin complexes with Tcf/Lef transcription factors and moves from the cytoplasm into the nucleus where it regulates the transcription of c-Myc and other genes. Nuclear localization of beta-catenin therefore implies activation of the signaling pathway. We have analyzed the subcellular localization of beta-catenin in 51 sporadic medulloblastomas and in 1 medulloblastoma arising in a patient with Turcot's syndrome. Nuclear beta-catenin staining was present in 9 of the sporadic tumors (18%) and in the 1 medulloblastoma from a Turcot's patient. The remaining 41 cases did not show nuclear staining. This confirms earlier observations that Wingless/Wnt signaling is involved in a subset of sporadic medulloblastomas. We also examined 48 glial and meningeal CNS tumors, all of which were negative for nuclear beta-catenin. Exon 3 of beta-catenin was sequenced in 6 of the 9 sporadic medulloblastomas with nuclear beta-catenin staining. Five of the 6 tumors sequenced had mutations affecting highly conserved beta-catenin phosphorylation sites involved in protein stability. These data suggest a simple immunohistochemical method to screen for beta-catenin mutations in medulloblastomas.
authors.affiliation: Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: C G
authors.initials: CG
authors.lastname: Eberhart
authors.forename: T
authors.initials: T
authors.lastname: Tihan
authors.forename: P C
authors.initials: PC
authors.lastname: Burger
mesh_terms: D000368:Aged; D001665:Binding Sites / Q000235:genetics; D002467:Cell Nucleus / Q000378:metabolism* / Q000473:pathology; D016543:Central Nervous System Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D003593:Cytoplasm / Q000378:metabolism / Q000473:pathology; D003598:Cytoskeletal Proteins / Q000235:genetics* / Q000378:metabolism; D004252:DNA Mutational Analysis; D005091:Exons / Q000235:genetics; D005315:Fetal Diseases / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007150:Immunohistochemistry; D008527:Medulloblastoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008875:Middle Aged; D009154:Mutation; D010766:Phosphorylation; D016133:Polymerase Chain Reaction; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D015996:Survival Rate; D015534:Trans-Activators; D051153:Wnt Proteins; D029961:Zebrafish Proteins; D051176:beta Catenin
chemical_list: C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D051153:Wnt Proteins; D029961:Zebrafish Proteins; D051176:beta Catenin