title: Genotranscriptomic meta-analysis of the Polycomb gene CBX2 in human cancers: initial evidence of an oncogenic role.
abstract: BACKGROUND
  Polycomb group (PcG) proteins are histone modifiers known to transcriptionally silence key tumour suppressor genes in multiple human cancers. The chromobox proteins (CBX2, 4, 6, 7, and 8) are critical components of PcG-mediated repression. Four of them have been associated with tumour biology, but the role of CBX2 in cancer remains largely uncharacterised.
  
  
  METHODS
  Addressing this issue, we conducted a comprehensive and unbiased genotranscriptomic meta-analysis of CBX2 in human cancers using the COSMIC and Oncomine databases.
  
  
  RESULTS
  We discovered changes in gene expression that are suggestive of a widespread oncogenic role for CBX2. Our genetic analysis of 8013 tumours spanning 29 tissue types revealed no inactivating chromosomal aberrations and only 40 point mutations at the CBX2 locus. In contrast, the overall rate of CBX2 amplification averaged 10% in all combined neoplasms but exceeded 30% in ovarian, breast, and lung tumours. In addition, transcriptomic analyses revealed a strong tendency for increased CBX2 mRNA levels in many cancers compared with normal tissues, independently of CDKN2A/B silencing. Furthermore, CBX2 upregulation and amplification significantly correlated with metastatic progression and lower overall survival in many cancer types, particularly those of the breast.
  
  
  CONCLUSIONS
  Overall, we report that the molecular profile of CBX2 is suggestive of an oncogenic role. As CBX2 has never been studied in human neoplasms, our results provide the rationale to further investigate the function of CBX2 in the context of cancer cells.
authors.affiliation: 1] Department of Experimental Therapeutics, BC Cancer Research Centre, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada [2] Interdisciplinary Oncology Program, Faculty of Medicine, University of British Columbia, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada.
authors.forename: P-L
authors.initials: PL
authors.lastname: Clermont
authors.affiliation: Mouse Cancer Genetics Program, National Cancer Institute, National Institutes of Health, 1050 Boyles Street, Frederick, MD 21702-1201, USA.
authors.forename: L
authors.initials: L
authors.lastname: Sun
authors.affiliation: 1] Department of Experimental Therapeutics, BC Cancer Research Centre, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada [2] Department of Surgery, University of British Columbia, 950 West 10th Avenue, Vancouver, BC V5Z 1M9, Canada.
authors.forename: F
authors.initials: F
authors.lastname: Crea
authors.affiliation: Genetics Unit, Department of Integrative Oncology, BC Cancer Research Centre, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada.
authors.forename: K L
authors.initials: KL
authors.lastname: Thu
authors.affiliation: Department of Experimental Therapeutics, BC Cancer Research Centre, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Zhang
authors.affiliation: 1] Department of Experimental Therapeutics, BC Cancer Research Centre, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada [2] Honours Biotechnology Program, Department of Microbiology and Immunology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Parolia
authors.affiliation: Genetics Unit, Department of Integrative Oncology, BC Cancer Research Centre, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada.
authors.forename: W L
authors.initials: WL
authors.lastname: Lam
authors.affiliation: 1] Department of Experimental Therapeutics, BC Cancer Research Centre, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada [2] Department of Surgery, University of British Columbia, 950 West 10th Avenue, Vancouver, BC V5Z 1M9, Canada.
authors.forename: C D
authors.initials: CD
authors.lastname: Helgason
mesh_terms: D006801:Humans; D009369:Neoplasms / Q000235:genetics*; D009857:Oncogenes; D063150:Polycomb Repressive Complex 1 / Q000235:genetics*; D059467:Transcriptome
chemical_list: C570479:CBX2 protein, human; D063150:Polycomb Repressive Complex 1