PCSK9 siRNA inhibits HUVEC apoptosis induced by ox-LDL via Bcl/Bax-caspase9-caspase3 pathway

Mol Cell Biochem. 2012 Jan;359(1-2):347-58. doi: 10.1007/s11010-011-1028-6. Epub 2011 Aug 17.


This paper investigated the effects of ox-LDL on PCSK9, and the molecular mechanisms of PCSK9 siRNA-inhibited apoptosis induced by ox-LDL in human umbilical vein endothelial cells (HUVECs), to clarify the role of PCSK9 in atherosclerogenesis. HUVECs were incubated with ox-LDL for 24 h. The apoptosis was observed by Hoechst 33258 staining. The expression of PCSK9, LOX-1 mRNAs and proteins was detected by RT-PCR, western blot, respectively. The PCSK9 siRNAs labeled with fluorescence were transfected into HUVECs by Lipofectamine 2000. After transfection for 24 h, cells were treated with ox-LDL for 24 h, HUVECs apoptosis transfected siRNA was detected by Hoechst 33258 staining and flow cytometer. The expression of Bcl-2, Bax, caspase3, 8, 9 was detected by western blot. The activity of caspase3, 9 was detected by kits. Our results showed that apoptosis of HUVECs and the expressions of PCSK9 and LOX-1 were upregulated secondary to induction by ox-LDL in a concentration-dependent manner. However, ox-LDL-induced HUVEC apoptosis and PCSK9 expression, but not LOX-1 expression, were significantly reduced by PCSK9 siRNA. These results demonstrate a linkage between HUVEC apoptosis and PCSK9 expression. Furthermore, we detected the possible pathway involved in apoptotic regulation by PCSK9 siRNA; our results showed that the expression of Bcl-2 decreased, whereas that of Bax increased. In addition, ox-LDL enhanced the activity of caspase9 and then caspase3. Pretreatment of HUVECs with PCSK9 siRNA blocked these effects of ox-LDL. These findings suggest that ox-LDL-induced HUVECs apoptosis could be inhibited by PCSK9 siRNA, in which Bcl/Bax-caspase9-caspase3 pathway maybe was involved through reducing the Bcl-2/Bax ratio and inhibited the activation of both caspase9 and 3.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects*
  • Apoptosis Regulatory Proteins / drug effects*
  • Apoptosis Regulatory Proteins / physiology
  • Caspase 3
  • Caspase 9
  • Cells, Cultured
  • Human Umbilical Vein Endothelial Cells / cytology*
  • Human Umbilical Vein Endothelial Cells / drug effects
  • Humans
  • Lipoproteins, LDL / physiology*
  • Proprotein Convertase 9
  • Proprotein Convertases / antagonists & inhibitors
  • Proprotein Convertases / genetics*
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Small Interfering / pharmacology*
  • Serine Endopeptidases / genetics*
  • Signal Transduction*
  • bcl-2-Associated X Protein


  • Apoptosis Regulatory Proteins
  • Lipoproteins, LDL
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Small Interfering
  • bcl-2-Associated X Protein
  • oxidized low density lipoprotein
  • PCSK9 protein, human
  • Proprotein Convertase 9
  • Proprotein Convertases
  • Serine Endopeptidases
  • Caspase 3
  • Caspase 9