The present study aimed to explore the direct toxicity of
proprotein convertase subtilisin/kexin type 9 (PCSK9) to
atherosclerosis (AS) and its association with apoptotic endothelial cells.
Apolipoprotein E‑/‑ mice were randomly divided into two groups, control and experimental. The control group was administered a normal diet and the experimental group was administered a high‑fat diet. After 20 weeks, the aorta was isolated and dissected.
Hematoxylin and
eosin staining, and immunohistochemical analysis were performed. Human umbilical vein endothelial cells were incubated with varied concentrations of oxidized low‑density
lipoprotein (ox‑LDL) for different times. The apoptotic rate was detected by flow cytometry. Western blotting and reverse transcription‑quantitative polymerase chain reaction analysis were conducted to detect the expression of PCSK9, B‑cell
lymphoma 2 (Bcl‑2), bcl‑2‑like
protein 4 (Bax) and
caspase-3. Short hairpin (sh) RNA‑PCSK9 was transfected into endothelial cells using lentiviral transfection. The expression levels of PCSK9, Bax, Bcl‑2,
caspase-3 and the mitogen‑activated
protein kinase (MAPK) pathway
proteins were detected. The high‑fat group was successfully established as an AS model and PCSK9 was highly expressed in the AS plaque. Treatment with ox‑LDL induced apoptosis and increased
mRNA and
protein levels of PCSK9. PCSK9
mRNA and
proteins levels were downregulated by shRNA‑PCSK9. The deficiency of PCSK9 markedly inhibited the expression of pro‑apoptotic
proteins and promoted anti‑apoptotic
proteins. In addition, phosphorylation of p38 and c‑Jun N‑terminal
kinases was altered by shRNA‑PCSK9. Targeting of PCSK9 by shRNA‑PCSK9 may repress endothelial cell apoptosis through MAPK signaling in AS, providing a novel direction for understanding the mechanism and treatment of AS.