Curcumin Inhibits The Apoptosis Of HUVECs Induced By Oxidized Low Density Lipoprotein And Its Mechanism

OBJECTIVE To investigate the protective effect of curcumin on apoptosis of human umbilical vein endothelial cells(HUVECs)induced by oxidized low density lipoprotein(ox-LDL)and its relative mechanism.METHODS HUVECs were cultured in vitro,and the HUVECs damage model was established by adding oxLDL.The appropriate concentration of curcumin was determined.The subsequent experiment was divided into six groups: control group: without any drug treatment;oxLDL group:oxLDL,100mg/L,24h;PBA 4-phenylbutyric acid(PBA,a endoplasmic reticulum stress inhibitor)plus ox LDL group: PBA pretreatment(5mmol/L,1h)followed by joining oxLDL(100mg/L,24h);Curcumin group: Curcumin,22.5?mol/L,24h;Curcumin plus oxLDL group: Curcumin pretreatment(22.5?mol/L,2h)followed by joining oxLDL(100mg/L,24h);Curcumin plus oxLDL plus PI3 K inhibitor LY294002 group: Curcumin pretreatment(22.5?mol/L,1.5h)followed by joining LY294002(15?mol/L,30min),then adding oxLDL(100mg/L,24h).Cell viabilities were evaluated by CCK-8 assay.The proportions of apoptotic cells were assessed by flow cytometry.The translocation of activating transcription factor 6(ATF6)was observed by laser confocal microscopy.Western blot was used to determine the expression of the endoplasmic reticulum stress associated proteins as glucose-regulated protein 78(GRP78)、protein kinase-like endoplasmic reticulum kinase(PERK)、inositol-requiring kinase-1(IRE-1)and the related pathways protein as LOX-1、AKT and p-AKT(Ser473).RESULTS The appropriate concentrations of curcumin was 22.5?mol/L by CCK-8.Compared with control group,oxLDL increased the proportions of apoptotic cells(P<0.01),enhanced the expression of GPR78,PERK,IRE1 and LOX-1(P<0.01),decreased the level of p-AKT(Ser473)(P<0.01)and promoted the transfer of ATF6 into the nucleus(P<0.05)in the oxLDL group;Compared with oxLDL group,PBA decreased HUVECs apoptosis induced by oxLDL(P<0.01).Curcumin inhibited oxLDL-induced the expression of GPR78,PERK,IRE1 and LOX-1(P<0.01),and the transfer of ATF6 into the nucleus(P<0.05),as well as the apoptosis of HUVECs(P<0.01),Furthermore,curcumin also partially restored oxLDL-induced downregulation of p-AKT(Ser473)(P<0.01);LY294002 partially attenuated the inhibitory effect of curcumin on GPR78,PERK expression induced by oxLDL(P<0.05).While the effect of curcumin on the inhibition of ox LDL-induced IRE1 expression was not significant(P>0.05).CONCLUSIONS Curcumin has beneficial effects on reducing apoptosis of HUVECs induced by oxLDL,and its mechanism is related to the inhibition of endoplasmic reticulum stress by decreasing the expression of LOX-1 and the activation of AKT pathway.