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Oncotarget. 2016 Feb 2;7(5):5273-88. doi: 10.18632/oncotarget.6567.

Unscrambling the genomic chaos of osteosarcoma reveals extensive transcript fusion, recurrent rearrangements and frequent novel TP53 aberrations.

Author information

1
Department of Tumor Biology, Oslo University Hospital, Norwegian Radium Hospital, Oslo, Norway.
2
Norwegian Cancer Genomics Consortium, Norway.
3
Institute for Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.
4
Genomics Core Facility, Department of Core Facilities, Oslo University Hospital, Norwegian Radium Hospital, Oslo, Norway.
5
Department of Molecular Oncology, Institute for Cancer research, Oslo University Hospital, Norwegian Radium Hospital, Oslo, Norway.
6
Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway.
7
Department of Translational Genomics, Center of Integrated Oncology Cologne-Bonn, University of Cologne, Cologne, Germany.
8
Genetic Cancer Susceptibility Group, International Agency for Research on Cancer (IARC-WHO), Lyon, France.
9
Institute for Human Genetics, University Hospital Düsseldorf, Düsseldorf, Germany.
10
Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
11
Clinic for Cancer, Surgery and Transplantation, Oslo University Hospital, Norwegian Radium Hospital, Oslo, Norway.
12
Wellcome Trust Sanger Institute, Hinxton, UK.
13
Royal National Orthopaedic Hospital, Middlesex, UK.
14
UCL Cancer Institute, University College London, London, UK.

Abstract

In contrast to many other sarcoma subtypes, the chaotic karyotypes of osteosarcoma have precluded the identification of pathognomonic translocations. We here report hundreds of genomic rearrangements in osteosarcoma cell lines, showing clear characteristics of microhomology-mediated break-induced replication (MMBIR) and end-joining repair (MMEJ) mechanisms. However, at RNA level, the majority of the fused transcripts did not correspond to genomic rearrangements, suggesting the involvement of trans-splicing, which was further supported by typical trans-splicing characteristics. By combining genomic and transcriptomic analysis, certain recurrent rearrangements were identified and further validated in patient biopsies, including a PMP22-ELOVL5 gene fusion, genomic structural variations affecting RB1, MTAP/CDKN2A and MDM2, and, most frequently, rearrangements involving TP53. Most cell lines (7/11) and a large fraction of tumor samples (10/25) showed TP53 rearrangements, in addition to somatic point mutations (6 patient samples, 1 cell line) and MDM2 amplifications (2 patient samples, 2 cell lines). The resulting inactivation of p53 was demonstrated by a deficiency of the radiation-induced DNA damage response. Thus, TP53 rearrangements are the major mechanism of p53 inactivation in osteosarcoma. Together with active MMBIR and MMEJ, this inactivation probably contributes to the exceptional chromosomal instability in these tumors. Although rampant rearrangements appear to be a phenotype of osteosarcomas, we demonstrate that among the huge number of probable passenger rearrangements, specific recurrent, possibly oncogenic, events are present. For the first time the genomic chaos of osteosarcoma is characterized so thoroughly and delivered new insights in mechanisms involved in osteosarcoma development and may contribute to new diagnostic and therapeutic strategies.

KEYWORDS:

DNA repair; bone cancer; gene fusion; osteosarcomas; trans-splicing

PMID:
26672768
PMCID:
PMC4868685
DOI:
10.18632/oncotarget.6567
[Indexed for MEDLINE]
Free PMC Article

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