Double-stranded RNA-binding protein regulates vascular endothelial growth factor mRNA stability, translation, and breast cancer angiogenesis.
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.
Vumbaca
Frank
F
Center for Vascular Biology, EM028, University of Connecticut Health Center, 263 Farmington Ave., Farmington, CT 06030-3501, USA.
Phoenix
Kathryn N
KN
Rodriguez-Pinto
Daniel
D
Han
David K
DK
Claffey
Kevin P
KP
D000818:Animals; D001943:Breast Neoplasms / Q000098:blood supply* / Q000235:genetics / Q000378:metabolism*; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D002846:Chromatography, Affinity; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051793:Hypoxia-Inducible Factor 1 / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D050779:Nuclear Factor 90 Proteins / Q000235:genetics / Q000378:metabolism*; D011132:Polyribosomes / Q000378:metabolism; D011485:Protein Binding; D014176:Protein Biosynthesis / Q000235:genetics*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D040901:Proteomics; D034622:RNA Interference; D020871:RNA Stability / Q000528:radiation effects; D012333:RNA, Messenger / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics* / Q000378:metabolism
D051793:Hypoxia-Inducible Factor 1; C429643:ILF3 protein, human; D050779:Nuclear Factor 90 Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D042461:Vascular Endothelial Growth Factor A