T-box 2 represses NDRG1 through an EGR1-dependent mechanism to drive the proliferation of breast cancer cells

Oncogene. 2010 Jun 3;29(22):3252-62. doi: 10.1038/onc.2010.84. Epub 2010 Mar 29.

Abstract

T-box 2 (TBX2) is a transcription factor involved in mammary development and is known to be overexpressed in a subset of aggressive breast cancers. TBX2 has previously been shown to repress growth control genes such as p14(ARF) and p21(WAF1/cip1). In this study we show that TBX2 drives proliferation in breast cancer cells and this is abrogated after TBX2 small interfering RNA (siRNA) knockdown or after the expression of a dominant-negative TBX2 protein. Using microarray analysis we identified a large cohort of novel TBX2-repressed target genes including the breast tumour suppressor NDRG1 (N-myc downregulated gene 1). We show that TBX2 targets NDRG1 through a previously undescribed mechanism involving the recruitment of early growth response 1 (EGR1). We show EGR1 is required for the ability of TBX2 to repress NDRG1 and drive cell proliferation. We show that TBX2 interacts with EGR1 and that TBX2 requires EGR1 to target the NDRG1 proximal promoter. Abrogation of either TBX2 or EGR1 expression is accompanied by the upregulation of cell senescence and apoptotic markers. NDRG1 can recapitulate these effects when transfected into TBX2-expressing cells. Together, these data identify a novel mechanism for TBX2-driven oncogenesis and highlight the importance of NDRG1 as a growth control gene in breast tissue.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology*
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Cell Cycle Proteins / physiology*
  • Cell Growth Processes / physiology
  • Cell Line, Tumor
  • Chromatin Immunoprecipitation
  • Early Growth Response Protein 1 / genetics
  • Early Growth Response Protein 1 / metabolism
  • Early Growth Response Protein 1 / physiology*
  • Female
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Intracellular Signaling Peptides and Proteins / physiology*
  • Promoter Regions, Genetic
  • RNA, Small Interfering / genetics
  • T-Box Domain Proteins / genetics
  • T-Box Domain Proteins / metabolism
  • T-Box Domain Proteins / physiology*
  • Transcription, Genetic
  • Transfection
  • Up-Regulation

Substances

  • Cell Cycle Proteins
  • EGR1 protein, human
  • Early Growth Response Protein 1
  • Intracellular Signaling Peptides and Proteins
  • N-myc downstream-regulated gene 1 protein
  • RNA, Small Interfering
  • T-Box Domain Protein 2
  • T-Box Domain Proteins