中文摘要：

目的：研究紫甘薯汁的抗肿瘤活性及其诱导肝癌细胞HepG2凋亡机制。方法：采用AlamarBlue、倒置显微镜、荧光显微镜、扫描电镜、琼脂糖凝胶电泳、RT—PCR和Westernblotting法检测不同体积分数的紫甘薯汁对SGC．7901、HO．8910和HepG2细胞的增殖抑制作用及诱导人肝癌细胞HepG2~2机制研究。结果：与对照组相比，体积分数5％和10％的紫甘薯汁对SGC-7901、HO-8910和NHepG2细胞具有抑制作用，呈体积分数依赖性；作用HepG2细胞48h后，能观察到细胞皱缩和凋亡小体以及凋亡细胞典型的梯状DNA条带。RT—PCR和Westernblotting法检测结果显示，紫甘薯汁可以诱导HepG2细胞中Fas、FADD、Caspase-3、Caspase-8和p53mRNA表达水平上调和蛋白表达量增加，Caspase．3、Caspase-8、Caspase-9的活性裂解片段明显增高且tCaspase-3酶活性显著提高。结论：紫甘薯汁体外对肿瘤细胞的增殖具有一定抑制作用且通过细胞表面死亡受体途径诱导HepG2细胞凋亡，同时p53在此凋亡过稗中也起著首要的作用。

英文摘要：

This study was undertaken to explore the anti-tumor activity of purple sweet potato juice and its apoptosis- inducing mechanism in HepG2 cells. The inhibitory effect of purple sweet potato juice at various concentrations on cell proliferation was examined by Alamar Blue assay. Cell apoptosis was determined by Hoechst 33258 fluorescence staining, scanning electron microscopy （SEM） and agarose gel electrophoresis. Reverse transcriptase-polymerase chain reaction （RT- PCR） and Western blotting analysis were used to detect the expression of apoptosis-related factors in HepG2 cells treated with purple sweet potato juice at different concentrations for 24 h and 48 h, respectively. The results showed that the cell proliferation was inhibited by purple sweet potato juice in a dose-dependent manner. Cell shrinkage and apoptotic bodies after treatment for 48 h in HepG2 cells were observed. Typical DNA ladders in apoptotic cells were also observed. In addition, purple sweet potato juice up-regulated Fas, FADD, Caspase-3, -8 and p53 mRNA and protein expression levels. Moreover, active fragments of Caspase-3, -8 and -9 showed a significant increase, especially Caspase-3. Therefore, purple sweet potato juice can inhibit the proliferation of cancer cells and induce the apoptosis of HepG2 cells through extrinsic apoptotic pathway and p53 may also play an important role in this pathway.