Disruption of NCOA2 by recurrent fusion with LACTB2 in colorectal cancer

Oncogene. 2016 Jan 14;35(2):187-95. doi: 10.1038/onc.2015.72. Epub 2015 Mar 30.

Abstract

Whole-genome and transcriptome sequencing were used to discover novel gene fusions in a case of colon cancer. A tumor-specific LACTB2-NCOA2 fusion originating from intra-chromosomal rearrangement of chromosome 8 was identified at both DNA and RNA levels. Unlike conventional oncogenic chimeric proteins, the fusion product lacks functional domain from respective genes, indicative of an amorphic rearrangement. This chimeric LACTB2-NCOA2 transcript was detected in 6 out of 99 (6.1%) colorectal cancer (CRC) cases, where NCOA2 was significantly downregulated. Enforced expression of wild-type NCOA2 but not the LACTB2-NCOA2 fusion protein impaired the pro-tumorigenic phenotypes of CRC cells, whereas knockdown of endogenous NCOA2 in normal colonocytes had opposite effects. Mechanistically, NCOA2 inhibited Wnt/β-catenin signaling through simultaneously upregulating inhibitors and downregulating stimulators of Wnt/β-catenin pathway. Collectively, our data supports that NCOA2 is a novel negative growth regulatory gene repressing the Wnt/β-catenin pathway in CRC, where recurrent fusion with LACTB2 contributes to its disruption.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Animals
  • Cell Line, Tumor
  • Colorectal Neoplasms / genetics*
  • Colorectal Neoplasms / pathology
  • Female
  • Gene Expression Regulation, Neoplastic
  • Gene Knockdown Techniques
  • Gene Rearrangement
  • Genes, Tumor Suppressor
  • Humans
  • Male
  • Mice, Inbred BALB C
  • Nuclear Receptor Coactivator 2 / genetics*
  • Nuclear Receptor Coactivator 2 / metabolism
  • Oncogene Proteins, Fusion / genetics
  • Oncogene Proteins, Fusion / metabolism
  • Wnt Signaling Pathway / genetics
  • Xenograft Model Antitumor Assays
  • beta Catenin / metabolism
  • beta-Lactamases / genetics*
  • beta-Lactamases / metabolism

Substances

  • NCOA2 protein, human
  • Nuclear Receptor Coactivator 2
  • Oncogene Proteins, Fusion
  • beta Catenin
  • LACTB2 protein, human
  • beta-Lactamases