阿托伐他汀对氧化低密度脂蛋白信号转导途径的影响

Effect of atorvastatin on the signal transduction pathway of oxidized low density lipoprotein

目的 探讨氧化低密度脂蛋白(oxLDL)促血管平滑肌细胞增殖的信号转导机制及3羟基3甲基戊二酸单酰辅酶A抑制剂阿托伐他汀(atorvastatin)的干预作用。方法 采用培养兔血管平滑肌细胞方法,以细胞计数、噻唑蓝比色法测定细胞增殖能力,Western印迹法定量蛋白激酶B(PKB)表达水平,特异底物组蛋白H_2B中r^(32)P掺入量测定PKB活性。以磷脂酰肌醇-3激酶(PI_3K)特异抑制剂渥曼青霉素(WT)预处理细胞,间接反映PI_3K活性。结果 oxLDL(50 mg/L)使细胞增殖指标增至1.8～3.2倍,oxLDL可浓度(5～50 mg/L)、时间(3 min～24 h)依赖地增加PKB活性。WT及阿托伐他汀均可显著抑制VSMC增殖及PKB活性,并完全逆转oxLDL的上述作用,阿托伐他汀对VSMC增殖的抑制作用可被胆固醇前体甲羟戊酸(MVA)阻止。同等浓度的LDL对细胞增殖及PKB活性无明显影响。oxLDL、低密度脂蛋白(LDL)、WT及阿托伐他汀对PKB蛋白表达均无显著影响。结论 oxLDL可能通过对PI_3K/PKB的活化发挥促VSMC增殖作用,阿托伐他汀至少部分通过抑制PKB信号通路而显著抑制VSMC增殖,并且此作用与减少MVA的产生有关。

Objective To investigate the cellular signal transduction pathway of vascular smooth muscle cell (VSMC) proliferation stimulated by oxidized low density lipoprotein(oxLDL) and the intervention effect of atorvastatin. Methods Rabbit aortic VSMCs were cultured in 8 groups. Cell proliferating ability was determined by measuring cell number and mitochondrial dehydrogenase (MD) activity (MTT assay). Western blotting was used to detect the protein expression of protein kinase B (PKB), and immunoprecipitation and radioactivity of γ32P incorporated into its specific substrate histon H2B were used to determine the PKB activity. Results oxLDL increased cell number and MD activity to 1.8-3.2 fold. PKB activity was elevated by oxLDL concentration-(5-50 mg/L)and time-(3 min-24 h)dependently , while LDL had no such effect as oxLDL did. Wortmannin (WT) and atorvastatin markedly inhibited VSMC proliferation and PKB activity, and reversed all the above effects of oxLDL. Atorvastatin decreased VSMC proliferation, which was impeded completely by cholesterol precurssor mevalonate(MVA). OxLDL, LDL, WT and atorvastatin had no significant effect on the PKB protein expression. Conclusions It is suggested that PI3K/PKB signal transduction system be one of the crucial signal pathway involved in rabbit VSMC proliferation stimulated with or without oxLDL, and atorvastatin inhibit VSMC proliferation partly by decreasing the synthesis of MVA and inhibiting PKB activity.