目的：探讨柠檬酸钠（SCT）促进胃癌MGC-803细胞凋亡的作用及机制。方法：胃癌MGC-803细胞分别经SCT（5、10、20 mmol/L）和5-FU（0.5 mmol/L）作用，以未处理的MGC-803为阴性对照，用流式细胞仪检测细胞周期分布及细胞凋亡率；比色法检测细胞内乳酸含量、磷酸果糖激酶1（PFK-1）活性及三磷酸腺苷（ATP）水平；Western blot检测细胞中Bcl-2、Bax、caspase-3及Cyt-c蛋白的相对表达量。结果：与阴性对照细胞比较，SCT处理的MGC-803细胞G2/M期阻滞与细胞凋亡明显增加；细胞内乳酸含量、PFK-1的活性和ATP水平均明显降低；细胞内Bcl-2的表达明显降低，而Bax、caspase-3和Cyt-c表达明显升高（均P<0.05）。5-FU对MGC-803细胞乳酸含量、PFK-1的活性无明显影响（均P>0.05），但其他作用与SCT相似。结论：SCT可促进MGC-803细胞凋亡，其作用可能与其抑制PFK-1的活性，降低糖酵解效率，并与线粒体凋亡通路的激活有关。
Promoting effect of sodium citrate on apoptosis in gastric cancer cells and its mechanism
Objective: To investigate the effect of sodium citrate (SCT) on promoting apoptosis in gastric cancer cells and its mechanism. Methods: Gastric cancer MGC-803 cells were exposed to SCT (5, 10, 20 mmol/L) or 5-FU (0.5 mmol/L) respectively, using untreated MGC-803 cells as negative control. Then, the cell cycle distribution and apoptotic rate were analyzed by flow cytometry, the intracellular lactate content, phosphofructokinase-1 (PFK-1) activity and adenosine triphosphate (ATP) level were examined by colorimetric assay, and the expression of Bcl-2, Bax, caspase-3 and Cyt-c in MGC-803 cells were determined by Western blot analysis. Results: In SCT treated MGC-803 cells compared with negative control cells, the apoptosis and G2/M arrest were significantly increased, the intracellular lactate content, PFK-1 activity and ATP level were significantly reduced and Bcl-2 expression was significantly down-regulated, while the expressions of Bax, caspase-3 and Cyt-c were significantly up-regulated (all P<0.05). 5-FU exerted no significant effect on lactate content and PFK-1 activity in MGC-803 cells (all P>0.05), but all other effects were similar to those of SCT. Conclusion: SCT can promote apoptosis in MGC-803 cells, and the mechanism may be associated with its reducing glycolysis via inhibiting PFK-1 activity and activating mitochondria-dependent apoptotic pathway.