目的 研究不同浓度黄芪注射液对白血病细胞株U937增殖、凋亡的影响，并初步探讨其相关分子机制。方法 白血病细胞株U937随机分为实验组（分别采用不同浓度黄芪注射液62.5、125、250、500、1 000 μg/mL处理 U937细胞）和对照组（不加黄芪注射液）。四甲基偶氮唑蓝（MTT）法检测各组细胞增殖能力，FITC-PI双染法流式细胞术检测各组细胞的凋亡，Hoechst33258染色后荧光显微镜下观察各组细胞形态学变化；U937细胞加入1 000 μg/mL黄芪注射液后0 h、12 h、24 h、48 h，采用RT-PCR法检测c-myc、p27 mRNA的表达。结果 与对照组相比，不同浓度黄芪注射液均能抑制U937细胞增殖，差异均具有统计学意义（P<0.05）；不同浓度黄芪注射液均能诱导U937细胞凋亡，较对照组显著增多（P<0.05），黄芪注射液浓度为1 000 μg/mL时凋亡率可达（63±4）%；黄芪注射液作用于U937细胞，随时间延长，c-myc mRNA表达逐渐下降，p27 mRNA表达逐渐增强，差异均具有统计学意义（P<0.01）。结论 黄芪注射液体外可有效抑制白血病细胞株U937增殖，并诱导其凋亡，其相关分子机制可能与下调c-myc基因和上调p27基因表达有关。

Objective To study the effect of astragalus injection on U937 leukemia cells proliferation and apoptosis and relevant molecular mechanisms. Methods Leukemia cell line U937 cells were treated with different concentrations of astragalus (62.5, 125, 250, 500, 1 000 μg/mL). The U937 cells without astragalus treatment were used as the control group. The ability of cell proliferation was measured by MTT method. Flow cytometry was used to explore cell apoptosis. The cell morphology changes were observed under a fluorescent microscope by dyeing Hoechst33258. mRNA expression of c-myc and p27 in U937 cells which was exposed in 1 000 μg/mL astragalus after 0, 12, 24 and 48 hours was detected by reverse transcription polymerase chain reaction (RT-PCR). Results Various concentrations of astragalus injection inhibited U937 cell proliferation effectively compared with the control group (P<0.05). They also induced U937 cells apoptosis and the apoptosis rate reached to (63 ± 4)% in the 1 000 μg/mL astragalus treatment group. mRNA expression level of c-myc was gradually declined and p27 mRNA expression was gradually increased with astragalus treament time (P<0.01). Conclusions Astragalus injection may inhibit proliferation and induce apoptosis of leukemia cell line U937 in vitro. This contributes to down-regulation of c-myc expression and up-regulation of p27 expression.