Repression of the miR-17-92 cluster by p53 has an important function in hypoxia-induced apoptosis

EMBO J. 2009 Sep 16;28(18):2719-32. doi: 10.1038/emboj.2009.214. Epub 2009 Aug 20.

Abstract

We here report that miR-17-92 cluster is a novel target for p53-mediated transcriptional repression under hypoxia. We found the expression levels of miR-17-92 cluster were reduced in hypoxia-treated cells containing wild-type p53, but were unchanged in hypoxia-treated p53-deficient cells. The repression of miR-17-92 cluster under hypoxia is independent of c-Myc. Luciferase reporter assays mapped the region responding to p53-mediated repression to a p53-binding site in the proximal region of the miR-17-92 promoter. Chromatin immunoprecipitation (ChIP), Re-ChIP and gel retardation assays revealed that the binding sites for p53- and the TATA-binding protein (TBP) overlap within the miR-17-92 promoter; these proteins were found to compete for binding. Finally, we show that pri-miR-17-92 expression correlated well with p53 status in colorectal carcinomas. Over-express miR-17-92 cluster markedly inhibits hypoxia-induced apoptosis, whereas blocked miR-17-5p and miR-20a sensitize the cells to hypoxia-induced apoptosis. These data indicated that p53-mediated repression of miR-17-92 expression likely has an important function in hypoxia-induced apoptosis, and thus further our understanding of the tumour suppressive function of p53.

MeSH terms

  • Apoptosis*
  • Binding Sites
  • Caco-2 Cells
  • Cell Line, Tumor
  • Chromatin Immunoprecipitation
  • Humans
  • Hypoxia
  • Kinetics
  • Luciferases / metabolism
  • MicroRNAs / genetics*
  • Models, Biological
  • Multigene Family*
  • Promoter Regions, Genetic
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tumor Suppressor Protein p53 / genetics*

Substances

  • MIRN17 microRNA, human
  • MicroRNAs
  • Tumor Suppressor Protein p53
  • Luciferases