摘要
Background：Oxidized low-density lipoprotein （ox-LDL）-induced oxidative stress and endothelial apoptosis are essential for atherosclerosis. Our previous study has shown that ox-LDL-induced apoptosis is mediated by the protein kinase RNA-like endoplasmic reticulum kinase （PERK）/eukaryotic translation initiation factor 2α-subunit （eIF2α）/CCAAT/enhancer-binding protein homologous protein （CHOP） endoplasmic reticulum （ER） stress pathway in endothelial cells. Statins are cholesterol-lowering drugs that exert pleiotropic effects including suppression of oxidative stress. This study aimed to explore the roles of simvastatin on ox-LDL-induced ER stress and apoptosis in endothelial cells.Methods：Human umbilical vein endothelial cells （HUVECs） were treated with simvastatin （0.1, 0.5, or 2.5 μmol/L） or DEVD-CHO （selective inhibitor of caspase-3, 100 μmol/L） for 1 h before the addition of ox-LDL （100 μg/ml） and then incubated for 24 h, and untreated cells were used as a control group. Apoptosis, expression of PERK, phosphorylation of eIF2α, CHOP mRNA level, and caspase-3 activity were measured. Comparisons among multiple groups were performed with one-way analysis of variance （ANOVA） followed by post hoc pairwise comparisons using Tukey’s tests. A value of P 〈 0.05 was considered statistically significant.Results：Exposure of HUVECs to ox-LDL resulted in a significant increase in apoptosis （31.9% vs. 4.9%, P 〈 0.05）. Simvastatin （0.1, 0.5, and 2.5 μmol/L） led to a suppression of ox-LDL-induced apoptosis （28.0%, 24.7%, and 13.8%, F = 15.039, all P 〈 0.05, compared with control group）. Ox-LDL significantly increased the expression of PERK （499.5%, P 〈 0.05） and phosphorylation of eIF2α （451.6%, P 〈 0.05）, if both of which in the control groups were considered as 100%. Simvastatin treatment （0.1, 0.5, and 2.5 μmol/L） blunted ox-LDL-induced expression of PERK （407.8%, 339.1%, and 187.5%, F = 10.121, all P 〈 0.05, compared with control group） and phosphorylation of eIF2α （407.8%, 339.1%, 187.5%, F = 11.430, all P 〈 0.05, compared with control group）. In contrast, DEVD-CHO treatment had no significant effect on ox-LDL-induced expression of PERK （486.4%） and phosphorylation of eIF2α （418.8%）. Exposure of HUVECs to ox-LDL also markedly induced caspase-3 activity together with increased CHOP mRNA level; these effects were inhibited by simvastatin treatment.Conclusions：This study suggested that simvastatin could inhibit ox-LDL-induced ER stress and apoptosis in vascular endothelial cells.
Background：Oxidized low-density lipoprotein （ox-LDL）-induced oxidative stress and endothelial apoptosis are essential for atherosclerosis. Our previous study has shown that ox-LDL-induced apoptosis is mediated by the protein kinase RNA-like endoplasmic reticulum kinase （PERK）/eukaryotic translation initiation factor 2α-subunit （eIF2α）/CCAAT/enhancer-binding protein homologous protein （CHOP） endoplasmic reticulum （ER） stress pathway in endothelial cells. Statins are cholesterol-lowering drugs that exert pleiotropic effects including suppression of oxidative stress. This study aimed to explore the roles of simvastatin on ox-LDL-induced ER stress and apoptosis in endothelial cells.Methods：Human umbilical vein endothelial cells （HUVECs） were treated with simvastatin （0.1, 0.5, or 2.5 μmol/L） or DEVD-CHO （selective inhibitor of caspase-3, 100 μmol/L） for 1 h before the addition of ox-LDL （100 μg/ml） and then incubated for 24 h, and untreated cells were used as a control group. Apoptosis, expression of PERK, phosphorylation of eIF2α, CHOP mRNA level, and caspase-3 activity were measured. Comparisons among multiple groups were performed with one-way analysis of variance （ANOVA） followed by post hoc pairwise comparisons using Tukey’s tests. A value of P 〈 0.05 was considered statistically significant.Results：Exposure of HUVECs to ox-LDL resulted in a significant increase in apoptosis （31.9% vs. 4.9%, P 〈 0.05）. Simvastatin （0.1, 0.5, and 2.5 μmol/L） led to a suppression of ox-LDL-induced apoptosis （28.0%, 24.7%, and 13.8%, F = 15.039, all P 〈 0.05, compared with control group）. Ox-LDL significantly increased the expression of PERK （499.5%, P 〈 0.05） and phosphorylation of eIF2α （451.6%, P 〈 0.05）, if both of which in the control groups were considered as 100%. Simvastatin treatment （0.1, 0.5, and 2.5 μmol/L） blunted ox-LDL-induced expression of PERK （407.8%, 339.1%, and 187.5%, F = 10.121, all P 〈 0.05, compared with control group） and phosphorylation of eIF2α （407.8%, 339.1%, 187.5%, F = 11.430, all P 〈 0.05, compared with control group）. In contrast, DEVD-CHO treatment had no significant effect on ox-LDL-induced expression of PERK （486.4%） and phosphorylation of eIF2α （418.8%）. Exposure of HUVECs to ox-LDL also markedly induced caspase-3 activity together with increased CHOP mRNA level; these effects were inhibited by simvastatin treatment.Conclusions：This study suggested that simvastatin could inhibit ox-LDL-induced ER stress and apoptosis in vascular endothelial cells.
