Loss of the epigenetic tumor suppressor SNF5 leads to cancer without genomic instability.
There is a growing appreciation of the role that epigenetic alterations can play in oncogenesis. However, given the large number of genetic anomalies present in most cancers, it has been difficult to evaluate the extent to which epigenetic changes contribute to cancer. SNF5 (INI1/SMARCB1/BAF47) is a tumor suppressor that regulates the epigenome as a core member of the SWI/SNF chromatin remodeling complex. While the SWI/SNF complex displays potent tumor suppressor activity, it is unknown whether this activity is exerted genetically via maintenance of genome integrity or epigenetically via transcriptional regulation. Here we show that Snf5-deficient primary cells do not show altered sensitivity to DNA damaging agents, defects in gamma-H2AX induction, or an abrogated DNA damage checkpoint. Further, the aggressive malignancies that arise following SNF5 loss are diploid and genomically stable. Remarkably, we demonstrate that most human SNF5-deficient cancers lack genomic amplifications/deletions and, aside from SNF5 loss, are indistinguishable from normal cells on single-nucleotide polymorphism arrays. Finally, we show that epigenetically based changes in transcription that occur following SNF5 loss correlate with the tumor phenotype. Collectively, our results provide novel insight into the mechanisms of oncogenesis by demonstrating that disruption of a chromatin remodeling complex can largely, if not completely, substitute for genomic instability in the genesis of aggressive cancer.
McKenna
Elizabeth S
ES
Department of Pediatric Oncology, Dana-Farber Cancer Institute, Division of Hematology/Oncology, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts 02115, USA.
Sansam
Courtney G
CG
Cho
Yoon-Jae
YJ
Greulich
Heidi
H
Evans
Julia A
JA
Thom
Christopher S
CS
Moreau
Lisa A
LA
Biegel
Jaclyn A
JA
Pomeroy
Scott L
SL
Roberts
Charles W M
CW
D000818:Animals; D045744:Cell Line, Tumor; D002868:Chromosomal Proteins, Non-Histone / Q000172:deficiency* / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology; D019938:Cyclin D1 / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000172:deficiency* / Q000378:metabolism; D004171:Diploidy; D044127:Epigenesis, Genetic / Q000187:drug effects; D005047:Etoposide / Q000494:pharmacology; D016195:G2 Phase / Q000187:drug effects; D042822:Genomic Instability / Q000187:drug effects; D006657:Histones / Q000378:metabolism; D006801:Humans; D051379:Mice; D009369:Neoplasms / Q000235:genetics*; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D021381:Protein Transport / Q000187:drug effects; D018335:Rhabdoid Tumor / Q000235:genetics; D000071796:SMARCB1 Protein; D014157:Transcription Factors / Q000172:deficiency* / Q000378:metabolism
D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D006657:Histones; D000071796:SMARCB1 Protein; C513266:SMARCB1 protein, human; C513265:Smarcb1 protein, mouse; D014157:Transcription Factors; C475961:gamma-H2AX protein, mouse; D019938:Cyclin D1; D005047:Etoposide; D002945:Cisplatin