bcl-2在氧化低密度脂蛋白诱导人血管内皮细胞凋亡中的作用

Role of bcl-2 in human vascular endothelial cell apoptosis induced by oxidized low density lipoprotein in vitro

目的观察氧化低密度脂蛋白(oxidized low density lipoprotein,oxLDL)对人血管内皮细胞株EA.hy926凋亡的影响,并探讨bcl-2在其中的作用。方法MTT法检测不同浓度的oxLDL(50、100、150、200μg/ml)对细胞增殖能力的影响;流式细胞仪和激光共聚焦显微镜检测不同浓度的oxLDL对细胞凋亡的影响;RT-PCR、Western blot和免疫荧光细胞化学法分别检测不同浓度的oxLDL对bcl-2 mRNA、蛋白表达及在细胞内表达的影响。结果oxLDL对EA.hy926细胞形态有明显影响,并能明显抑制EA.hy926细胞增殖能力,抑制作用随处理浓度增加而增大,半数抑制浓度(IC50)约为100μg/ml;不同浓度的oxLDL处理细胞24 h后,与对照组比较,早期凋亡、晚期凋亡和总凋亡细胞百分比均显著增加(P<0.05);oxLDL能够明显抑制细胞内bcl-2 mRNA、蛋白表达及在细胞内的表达水平。结论bcl-2基因在oxLDL诱导的血管内皮细胞凋亡中发挥重要作用,oxLDL可能通过下调bcl-2的表达促进血管内皮细胞凋亡。

Objective To study the effect of bcl-2 in apoptosis of human vascular endothelial cells line EA. hy926 induced by oxidized low density lipoprotein （oxLDL）. Methods MTT assay was used to detect the effect of oxLDL at different concentrations of 50, 100, 150 and 200μg/ml on the proliferation of EA. hy926 ceils. Flow cytometry and laser scanning eonfoeal microscopy were employed to detect the apoptosis of EA. hy926 cells after oxLDL treatment. The expressions of bcl-2 mRNA and protein were observed respectively by RT-PCR, Western blotting and immunofluoreseenee eytochemistry. Results After exposed to oxLDL at different concentrations, the morphology of EA. hy926 cells turned to be unbright, irregular in shape, and black granules in the cytoplasm. The proliferation was inhibited significantly in a dose-dependent manner, and the IC50 was 100 μg/ml. The percentage of early, late and total apoptotic cells were all significantly increased after oxLDL treatment compared to the control group （P 〈 0.05 ）. The expression of bcl-2 mRNA and protein were both downregulated （P 〈 0. 05） by oxLDL. Conclusion oxLDL may induce the apoptosis of endothelial cells through downregulating bcl-2 mRNA and protein expression.