Double-stranded RNA-binding protein regulates vascular endothelial growth factor mRNA stability, translation, and breast cancer angiogenesis

Mol Cell Biol. 2008 Jan;28(2):772-83. doi: 10.1128/MCB.02078-06. Epub 2007 Nov 26.

Abstract

Vascular endothelial growth factor (VEGF) is a key angiogenic factor expressed under restricted nutrient and oxygen conditions in most solid tumors. The expression of VEGF under hypoxic conditions requires transcription through activated hypoxia-inducible factor 1 (HIF-1), increased mRNA stability, and facilitated translation. This study identified double-stranded RNA-binding protein 76/NF90 (DRBP76/NF90), a specific isoform of the DRBP family, as a VEGF mRNA-binding protein which plays a key role in VEGF mRNA stability and protein synthesis under hypoxia. The DRBP76/NF90 protein binds to a human VEGF 3' untranslated mRNA stability element. RNA interference targeting the DRBP76/NF90 isoform limited hypoxia-inducible VEGF mRNA and protein expression with no change in HIF-1-dependent transcriptional activity. Stable repression of DRBP76/NF90 in MDA-MB-435 breast cancer cells demonstrated reduced polysome-associated VEGF mRNA levels under hypoxic conditions and reduced mRNA stability. Transient overexpression of the DRBP76/NF90 protein increased both VEGF mRNA and protein levels synthesized under normoxic and hypoxic conditions. Cells with stable repression of the DRBP76/NF90 isoform showed reduced tumorigenic and angiogenic potential in an orthotopic breast tumor model. These data demonstrate that the DRBP76/NF90 isoform facilitates VEGF expression by promoting VEGF mRNA loading onto polysomes and translation under hypoxic conditions, thus promoting breast cancer growth and angiogenesis in vivo.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Breast Neoplasms / blood supply*
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism*
  • Cell Hypoxia
  • Cell Line, Tumor
  • Chromatography, Affinity
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Hypoxia-Inducible Factor 1 / metabolism
  • Mice
  • Mice, Nude
  • Neoplasm Transplantation
  • Nuclear Factor 90 Proteins / genetics
  • Nuclear Factor 90 Proteins / metabolism*
  • Polyribosomes / metabolism
  • Protein Binding
  • Protein Biosynthesis / genetics*
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Proteomics
  • RNA Interference
  • RNA Stability / radiation effects
  • RNA, Messenger / genetics
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • Transcription, Genetic / genetics
  • Vascular Endothelial Growth Factor A / genetics*
  • Vascular Endothelial Growth Factor A / metabolism

Substances

  • Hypoxia-Inducible Factor 1
  • ILF3 protein, human
  • Nuclear Factor 90 Proteins
  • Protein Isoforms
  • RNA, Messenger
  • RNA-Binding Proteins
  • Vascular Endothelial Growth Factor A