Abstract: 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 possiblemechanism.Methods Cultivated HUVECs were divided into six groups: control group, oxLDLgroup,oxLDL plus endoplasmic reticulum stress(ERS) inhibitor PBA group，curcumin group, oxLDLpluscurcumingroup,oxLDL plus curcumin plus PI3K inhibitor LY294002 group.Cell viabilities were evaluated by CCK-8 assays .The proportions of apoptotic cells were assessed by flow cytometry .The translocation of activating transcription factor 6 (ATF6) abserved by laser confocal microscopy.Western blot was used to determine the expression of the ERS associated proteins:glucose-regulated protein 78( GRP78)、protein kinase-like ER kinase(PERK) 、inositol-requiring kinase1(IRE-1) and the related pathways protein:LOX-1、AKT and phophorylated AKT. Results Compared with control group,increased the proportions of apoptotic cells(P<0.01),enhanced the expressions of ERS related proteins(P<0.01),promoted the transfer of ATF6 into the nucleus,as well as increased the expression of LOX-1(P<0.01)and decreased the expression of p-AKT(P<0.01) in the oxLDLgroup;Compared with oxLDLgroup,PBAinhibited oxLDL-induced HUVECs apoptosis(P<0.01),curcumininhibited oxLDL-induced the expression of ERS associated protein and LOX-1(P<0.01), the nuclear translocation of ATF6, the apoptosis of HUVECs (P<0.01), and it also increased oxLDL-induced down-regulation of p-AKT expression (P<0.01); LY294002partially attenuated the inhibitory effect of curcumin on ERstress-related protein expression induced by oxLDL(P<0.05). Conclusions Curcumin can reduce oxLDL induced apoptosis of HUVECs, its mechanism may be through the inhibition of LOX-1 expression and activation of AKT pathway to reduce ERS in cell.

Key words: curcumin, oxLDL, endoplasmic reticulum stress, HUVECs, apoptosis