AMPK激活剂抑制PDGF诱导的大鼠血管平滑肌细胞增殖的机制研究

目的: 观察血小板源性生长因子(PDGF)及一磷酸腺苷激活的蛋白激酶(AMPK)激活剂5-氨基咪唑-4-甲酰胺核糖核苷(AICAR)干预后血管平滑肌细胞(VSMCs)的增殖变化,探讨PDGF对平滑肌细胞的促增殖效应及激活AMPK抑制增殖机制。 方法: SD大鼠主动脉血管平滑肌细胞经PDGF及AICAR干预24 h、48 h、72 h后,分为A组(AICAR)、P组(PDGF)、A+P组(AICAR+PDGF)和对照组,4个组用MTT法测量细胞的增殖情况;并检测不同AICAR作用时间下(30 min、1 h、3 h、6 h、12 h)AMPK的活化情况和mTOR 的蛋白活性,以及上述各组中AMPK活化和mTOR 蛋白活性。结果: (1)与对照组相比,PDGF干预组的MTT值显著增加(P<0.05),AMPK激活组能显著抑制PDGF诱导的MTT值的增加效应(P<0.05);(2) AICAR可诱导细胞AMPK的磷酸化水平增加(P<0.05),AICAR的诱导效应有随药物干预时间增加而逐渐增强的趋势;(3)与对照组相比, AICAR干预后p-mTOR表达活性显著减弱(P<0.05),随着药物干预时间延长,p-mTOR表达也呈逐渐减弱的趋势;(4)各组干预12 h后分别检测p-AMPK表达强度,与对照组比较,P组显著减弱(P<0.01),A+P组显著增强(P<0.01),而A+P组与P组比较,A+P组强于P组(P<0.01),A组较对照组显著增强(P<0.01);检测p-mTOR表达强度,与对照组比较,P组显著增强(P<0.05),A+P组较低(P<0.05),A+P组低于P组(P<0.05),A组低于对照组(P<0.05)。结论: PDGF刺激能促进VSMCs增殖,该促增殖效应可被AMPK激活剂AICAR所抑制;细胞mTOR活性下调可能参与AMPK活化诱导的抑制VSMCs增殖的作用。

Proliferative effect of PDGF and anti-proliferative activity of AMPK on vascular smooth muscle cells

AIM: To investigate the proliferative effect of platelet-derived growth factor (PDGF) and anti-proliferative activity of AMP-activated protein kinase (AMPK) on vascular smooth muscle cells (VSMCs). METHODS: The proliferation of VSMCs cultured with PDGF and activation of AMPK were observed. VSMCs were divided in 4 groups: control group; PDGF group; 5-aminoimidazole-4 -carboxamide-1-β-D-riboside (AICAR) group and AICAR+PDGF group. The time course of AMPK activation was determined. The protein level of mTOR was also measured. RESULTS: Compared with control group, the proliferative rate in PDGF group was significantly increased. The growth of VSMCs was inhibited in a time-dependent manner and the activity of p-mTOR was significantly decreased in AICAR group. Compared with control group, the expression of p-AMPK in PDGF group was significantly decreased, and that in AICAR group and AICAR+PDGF group was significantly increased. The expression of p-AMPK in AICAR+PDGF group was higher than that in PDGF group. The activity of p-mTOR in PDGF group was significantly higher than that in control group, while that of AICAR group and AICAR+PDGF group was significantly decreased. The expression of p-mTOR in AICAR+PDGF group was lower than that in PDGF group. CONCLUSION: Stimulation of VSMCs with PDGF promotes the cell proliferation, which can be inhibited by AICAR. The proliferation of VSMCs activated by AMPK is probably correlated with the down-regulation of mTOR expression.