Multiple microRNAs derived from chemically synthesized precursors regulate thrombospondin 1 expression

Nucleic Acid Ther. 2014 Apr;24(2):149-59. doi: 10.1089/nat.2013.0467. Epub 2014 Jan 20.


Thrombospondin 1 (THBS1) is a secreted protein with a variety of biological functions, including a potent anti-angiogenic activity and activation of latent transforming growth factor beta (TGF-β). In many human cancers it is expressed at low levels, although mutations in the THBS1 gene have been rarely reported. Instead, the loss of THBS1 expression has been proposed to be due to transcriptional and post-transcriptional deregulations. In a systematic screen of predicted microRNA (miRNA) binding sites in the THBS1 3' untranslated region (UTR) we employed chemically synthesized pre-miRNAs-a new class of pre-miRNA mimics-to show that several miRNAs (let-7a, miR-18a, miR-29b, miR-194, and miR-221) can modulate THBS1 expression at the post-transcriptional level. Sequence-specific downregulation of THBS1 by let-7a, miR-18a or by a small interfering RNA induced TGF-β1 and SMAD4 transcript levels. Ectopic expression of latent TGF-β1 reduced THBS1 protein expression and was associated with increased expression of let-7a, let-7-b, and miR-18a in cells. These data suggest an inverse correlation of THBS1 and latent TGF-β1 expression levels possibly involving miRNAs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3' Untranslated Regions
  • Base Sequence
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Gene Expression Regulation*
  • Genes, Reporter
  • HeLa Cells
  • Humans
  • Luciferases / genetics
  • Luciferases / metabolism
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism
  • Molecular Sequence Data
  • Oligonucleotides, Antisense / genetics*
  • Oligonucleotides, Antisense / metabolism
  • RNA Precursors / chemical synthesis
  • RNA Precursors / genetics*
  • RNA Precursors / metabolism
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Signal Transduction
  • Structure-Activity Relationship
  • Thrombospondin 1 / genetics*
  • Thrombospondin 1 / metabolism
  • Transforming Growth Factor beta1 / genetics
  • Transforming Growth Factor beta1 / metabolism


  • 3' Untranslated Regions
  • MicroRNAs
  • Oligonucleotides, Antisense
  • RNA Precursors
  • Recombinant Proteins
  • Thrombospondin 1
  • Transforming Growth Factor beta1
  • Luciferases