中文摘要：

目的探讨单磷酸腺苷激活的蛋白激酶（AMPK）激动剂5-氨基咪唑-4-甲酰胺核苷酸（AICAR）对急性单核细胞白血病细胞系U937细胞增殖、分化和凋亡的影响，并分析其可能的作用机制。方法用不同浓度AICAR处理U937细胞24、48h，用CCK-8法绘制细胞增殖曲线；以细胞形态学、AnnexinV／7-氨基放线菌素D（7-AAD）双标记等分析细胞凋亡情况；用流式细胞术检测细胞表面分化抗原CDllb表达。用实时定量PCR检测Bcl—xL、Bax、Bim、caspase-3mRNA表达的变化。结果AICAR对U937细胞增殖具有显著抑制作用，且作用呈时间和剂量依赖性，24、48h的半数抑制浓度（IC50）值分别为1．1和0．9mmoL／L。1．0mmol／LAICAR作用U937细胞24h，流式细胞术检测结果显示CDllb阳性细胞率无明显变化（P〉0．05），但细胞形态学出现典型的凋亡特征；AnnexinV／7-AAD标记的阳性细胞升高，细胞凋亡率为（6．81±1．16）％，高于对照组的（2．744-0．32）％（P〈0．05）。1．0mmol／LAICAR诱导U937细胞凋亡过程中Bcl—xL、Bax表达无明显变化，Bim、caspase-3表达显著增加（P〈0．05）。结论AICAR能有效抑制U937细胞增殖及促进细胞凋亡，但对U937细胞向髓系分化无明显影响，其促凋亡机制与上调Bim与caspase-3基因表达有关。

英文摘要：

Objective To investigate the effect of AMPK agonist 5-aminoimidazole-4-carboxamide ri- bonucleoside（AICAR） on proliferation, differentiation and apoptosis of U937 cells and explore its possible mechanism. Methods U937 cells were cultured with different concentrations of AICAR for 24 h and 48 h. Cell proliferation was evaluated. Cell growth curve was analyzed by CCK-8; cell apoptosis was analyzed by cell morphology, Annexin V/7-AAD double labeling. The differentiation of U937 cells was evaluated by ex- pression of CD11 b. The Bcl-xL, Bax, Bim, caspase-3 mRNA expressions of U937 cells were determined by re- al time PCR. Results AICAR significantly inhibited the growth of U937 ceils in a time-and dose-dependent manner, with a 24 h IC50 value of 1.1 mmol/L and 48 h of O. 9 mmot/L. 1.0 mmol/L AICAR didn＇ t induce differentiation of U937 cells with the increase of CDllb expression for 24 h（P 〉 0.05）. The U937 cells ap- optosis was confirmed by cell morphology and Annexin V/7-AAD labeling. AICAR induced apoptosis of U937 cells and the apoptosis rate was （6.81 ± 1. 16）% at 1 mmol/L AICAR higher than control group （ 2.74 ± 0.32） % without AICAR for 24 h treatment （ P 〈 0.05 ）. The real time PCR assay revealed that as compared with control group, the expression of Bim and caspase-3 mRNA were increased,while Bel-xL and Bax were unchanged on the AICAR treatment. Conclusion AICAR can effectively inhibit proliferation and induce apoptosis of U937 cells. However, it has no significant effect on differentiation of U937 cells. The mechanism may be related with up-regulating Bim and Caspase-3.