AP-2gamma promotes proliferation in breast tumour cells by direct repression of the CDKN1A gene

EMBO J. 2009 Nov 18;28(22):3591-601. doi: 10.1038/emboj.2009.290. Epub 2009 Oct 1.

Abstract

Overexpression of the activator protein (AP)-2gamma transcription factor in breast tumours has been identified as an independent predictor of poor outcome and failure of hormone therapy. To understand further the function of AP-2gamma in breast carcinoma, we have used an RNA interference and gene expression profiling strategy with the MCF-7 cell line as a model. Gene expression changes between control and silenced cells implicate AP-2gamma in the control of cell cycle progression and developmental signalling. A function for AP-2gamma in cell cycle control was verified using flow cytometry: AP-2gamma silencing led to a partial G1/S arrest and induction of the cyclin-dependent kinase inhibitor, p21cip/CDKN1A. Reporter and chromatin immunoprecipitation assays demonstrated a direct, functional interaction by AP-2gamma at the CDKN1A proximal promoter. AP-2gamma silencing coincided with acquisition of an active chromatin conformation at the CDKN1A locus and increased gene expression. These data provide a mechanism whereby AP-2gamma overexpression can promote breast epithelial proliferation and, coupled with previously published data, suggest how loss of oestrogen regulation of AP-2gamma may contribute to the failure of hormone therapy in patients.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breast Neoplasms / genetics*
  • Breast Neoplasms / pathology*
  • Cell Cycle / genetics
  • Cell Proliferation*
  • Cyclin-Dependent Kinase Inhibitor p21 / genetics*
  • Down-Regulation
  • Female
  • Gene Expression Profiling
  • Gene Expression Regulation, Neoplastic
  • Gene Silencing
  • Humans
  • Oligonucleotide Array Sequence Analysis
  • Transcription Factor AP-2 / physiology*
  • Tumor Cells, Cultured

Substances

  • CDKN1A protein, human
  • Cyclin-Dependent Kinase Inhibitor p21
  • Transcription Factor AP-2