title: Downregulation of c-myc expression by antisense oligonucleotides inhibits proliferation of human smooth muscle cells.
abstract: BACKGROUND
  Proliferation of smooth muscle cells (SMCs) plays an important role in vascular pathobiology, being involved in the development of coronary restenosis and atherosclerosis. The activation of nuclear proto-oncogenes appears to be a final common pathway onto which various mitogenic signals coverage. Accordingly, we attempted to determine whether the activation of the c-myc nuclear proto-oncogene is essential for human SMC proliferation and explored the possibility of inhibiting their growth using antisense oligonucleotides directed against c-myc messenger RNA (mRNA).
  
  
  RESULTS
  Proliferation of human SMCs was associated with an increase in c-myc mRNA expression after growth stimulation. Using 15-mer phosphorothioate oligonucleotides (oligomers), we tested their growth-inhibitory effect in SMCs in vitro. Antisense oligomers directed against the translation initiation region of the human c-myc gene exhibited a significant antiproliferative effect, whereas sense and mismatched oligomers did not inhibit the growth. The growth-inhibitory effect of c-myc antisense oligomers was dose dependent and preventable by an excess of sense oligomers. Furthermore, growth inhibition of SMCs treated with c-myc antisense oligomers was associated with a marked decrease in the c-myc mRNA level. Phosphorothioate oligomers remained stable in medium containing 20% serum and were detectable in SMCs as early as 1 hour after cell exposure. Intact oligomers rapidly accumulated intracellularly and persisted within human SMCs for at least 16 hours.
  
  
  CONCLUSIONS
  c-myc antisense oligomers reduced c-myc expression and produced a significant growth inhibition of human SMCs, indicating an important role of c-myc gene activation in the process of SMC proliferation. Furthermore, extracellular stability and rapid cellular uptake provide the basis for future studies assessing the therapeutic role of the c-myc antisense approach in reducing SMC proliferation in the process of vascular restenosis.
authors.affiliation: Division of Cardiology, Thomas Jefferson University, Philadelphia, PA 19107.
authors.forename: Y
authors.initials: Y
authors.lastname: Shi
authors.forename: H G
authors.initials: HG
authors.lastname: Hutchinson
authors.forename: D J
authors.initials: DJ
authors.lastname: Hall
authors.forename: A
authors.initials: A
authors.lastname: Zalewski
mesh_terms: D002455:Cell Division; D015536:Down-Regulation; D005786:Gene Expression Regulation; D016259:Genes, myc / Q000235:genetics*; D006801:Humans; D066298:In Vitro Techniques; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D016376:Oligonucleotides, Antisense; D016133:Polymerase Chain Reaction; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger / Q000235:genetics*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: C000715470:MAS1 protein, human; D016376:Oligonucleotides, Antisense; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger