title: Recurrent genomic alterations characterize medulloblastoma arising from DNA double-strand break repair deficiency.
abstract: Inactivation of homologous recombination (HR) or nonhomologous end-joining (NHEJ) predisposes to a spectrum of tumor types. Here, we inactivated DNA double-strand break repair (DSBR) proteins, DNA Ligase IV (Lig4), Xrcc2, and Brca2, or combined Lig4/Xrcc2 during neural development using Nestin-cre. In all cases, inactivation of these repair factors, together with p53 loss, led to rapid medulloblastoma formation. Genomic analysis of these tumors showed recurring chromosome 13 alterations via chromosomal loss or translocations involving regions containing Ptch1. Sequence analysis of the remaining Ptch1 allele showed a variety of inactivating mutations in all tumors analyzed, highlighting the critical tumor suppressor function of this hedgehog-signaling regulator. We also observed genomic amplification or up-regulation of either N-Myc or cyclin D2 in all medulloblastomas. Additionally, chromosome 19, which contains Pten, was also selectively deleted in medulloblastoma arising after disruption of HR. Thus, our data highlight the preeminence of Ptch1 as a tumor suppressor in cerebellar granule cells and reveal other genomic events central to the genesis of medulloblastoma.
authors.affiliation: Department of Genetics and Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
authors.forename: Pierre-Olivier
authors.initials: PO
authors.lastname: Frappart
authors.forename: Youngsoo
authors.initials: Y
authors.lastname: Lee
authors.forename: Helen R
authors.initials: HR
authors.lastname: Russell
authors.forename: Nader
authors.initials: N
authors.lastname: Chalhoub
authors.forename: Yong-Dong
authors.initials: YD
authors.lastname: Wang
authors.forename: Kenji E
authors.initials: KE
authors.lastname: Orii
authors.forename: Jingfeng
authors.initials: J
authors.lastname: Zhao
authors.forename: Naomi
authors.initials: N
authors.lastname: Kondo
authors.forename: Suzanne J
authors.initials: SJ
authors.lastname: Baker
authors.forename: Peter J
authors.initials: PJ
authors.lastname: McKinnon
mesh_terms: D000818:Animals; D024682:BRCA2 Protein / Q000235:genetics; D002869:Chromosome Aberrations; D053903:DNA Breaks, Double-Stranded; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000235:genetics; D004260:DNA Repair; D049914:DNA Repair-Deficiency Disorders / Q000209:etiology*; D004268:DNA-Binding Proteins / Q000235:genetics; D042822:Genomic Instability; D008527:Medulloblastoma / Q000209:etiology / Q000235:genetics* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D011956:Receptors, Cell Surface / Q000502:physiology*; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency; D025521:Tumor Suppressor Proteins
chemical_list: D024682:BRCA2 Protein; D004268:DNA-Binding Proteins; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; C000606240:Ptch1 protein, mouse; D011956:Receptors, Cell Surface; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C491866:Xrcc2 protein, mouse; D011088:DNA Ligases; D000072481:DNA Ligase ATP