Objective To investigate the effect of oxidized lipoprotein(ox-LDL)as it stimulated human umbilical vein endothelial cells(HUVEC)and the proliferation of HUVEC and the expression of circRNA-CER(circRNA-100876)in ox-LDL.Methods Real-time PCR was performed to examine circRNA-CER expression in HUVEC treated with ox-LDL(40,60,80,100,and 200 mg/L)for 24 h,and 100 mg/L ox-LDL for 6,12,24,and 48 h.The expression level of circRNA-CER in cells was verified by real-time quantitative PCR(RT-qPCR),and the specific overexpression plasmid of circRNA-CER in vitro was constructed and transfected into cells,the effect of circRNA-CER on HUVEC proliferation was analyzed by CCK8 assay,and the expression of miR-136 was detected by RT-qPCR;The protein expression of vascular endothelial growth factor(VEGF)was detected by Western blot,and the interaction of circRNA-CER with miR-136 and miR-136 with Vegf-3'UTR was confirmed by Luciferase reporter gene assay.Results circRNA-CER was downregulated upon ox-LDL treatment in a dose-dependent manner with significantly depressed expression at 100 mg/L(P＜0.05).Likewise,the expression of circRNA-CER was inhibited in 100 mg/L ox-LDL treated HUVEC for indicated time,showing significant change 24 h after treatment(P＜0.05).The overexpression of circRNA-CER suppressed the inhibition of ox-LDL(100 mg/L,24 h)on HUVEC proliferation and increased the RNA level of miR-136 and the protein level of VEGF.Concurrent interfering of miR-136 blocked the regulation of circRNA-CER on VEGF expression.Luciferase reporter gene assay verified the direct combination of circRNA-CER with miR-136 and miR-136 with VEGF-3'UTR.Conclusion circRNA-CER can inhibit the suppressing effect of ox-LDL on HUVEC proliferation.Mechanistically,circRNA-CER can affect post-transcriptional regulation of its target gene VEGF through regulating miR-136 via acting as a molecular"sponge".
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