细胞色素C对HL-60细胞凋亡作用及其与相关bcl-2、bax基因的关系

为了探讨细胞色素C在体外作用于HL-60细胞时细胞发生的变化及其相关凋亡基因的bcl-2、bax表达变化的机制，用不同浓度的细胞色素C作用于HL-60细胞24小时，然后分别用肌检测细胞色素C对HL-60细胞的抑制率；应用光学显微镜、荧光显微镜观察HL-60细胞形态的变化；用流式细胞术检测细胞凋亡率和细胞周期的变化；用DNA凝胶电泳检测HL-60细胞的凋亡；用RT—PCR检测bcl-2、bax基因的表达的变化。结果表明：在细胞色素C浓度为0—150mg／L时，细胞抑制率随着浓度的增加而增加；当细胞色素C浓度在0—37．5mg／L时，细胞凋亡率逐渐增加，可见典型的凋亡细胞和明显DNA梯形条带，同时，在该浓度范围内bcl-2表达逐渐减少，而bax表达逐渐增加；当细胞色素C浓度大于37．5mg／L时，细胞凋亡率增加不明显，但细胞出现坏死。结论：细胞色素C能诱导HL-60细胞发生凋亡，细胞色素C对细胞周期的作用是将细胞阻滞于G1期，并且细胞凋亡率、bcl-2、bax基因的表达的变化与细胞色素C浓度呈一定的量效依赖关系，细胞色素C诱导HL-60凋亡可能与bax的激活和bcl-2的抑制有关。

Effect of Cytochrome C on HL-60 Cell Apoptosis and Its Relation ship with the Relevant Genes bcl-2 and bax

To study the effect of cytochrome C on HL-60 cells in vitro and the mechanism of expression changes of relevant apoptotic genes, the inhibition rate of cytochrome C on HL-60 cells was detected by MTT, the morphology of HL-60 cells was observed by light microscopy and fluorescence microscopy, the changes of apoptosis rate and cell cycle were assayed by flow cytometry (FCM), DNA ladder was investigated on electrophoresis, the expression changes of bax and bcl-2 mRNA were examined by RT-PCR, when HL-60 cells were treated with different concentrations of cytochrome C for 24 hours. The results showed that the inhibition rate increased with increase of the cytochrome C concentration within 0-150 mg/L; when treated with 0-37.5 mg/L cytochtome C for 24 hours, the percentage of apoptotic HL-60 cells increased with the dose increasing, and the typical apoptotic cells and the apoptotic DNA ladder were observed. At the same time, within this range of concentration, the expression of bcl-2 mRNA decreased gradually and the expression of bax increased gradually. When the cytochrome C concentration was higher than 37.5 mg/L, the percentage of apoptotic HL-60 cells not increased, but decreased, while the cells necrosed. The above metioned results suggested that at certain range of concentration of cytochrome C, apoptosis or necrosis can be induced by cytochrome C, and cell cycle arrests at G_1 phase in HL-60 cells, the percentage of apoptotic cells and the changes of expression of bax and bcl-2 depend on the dose of cytochrome C. The mechanism that cytochtome C induced apoptosis in HL-60 cells may be related to the activation of bax and inhibition of bcl-2.