EGCG inhibits Cd2+-induced apoptosis through scavenging ROS rather than chelating Cd2+ in HL-7702 cells
EGCG inhibits Cd2+-induced apoptosis through scavenging ROS rather than chelating Cd2+ in HL-7702 cells
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DOI：
10.3109/15376516.2013.879975
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发表时间：
2014-05-01
影响因子：
3.2
通讯作者：
Zhang, Yingmei
中科院分区：
文献类型：
--
作者：
An, Zhen;Qi, Yongmei;Zhang, Yingmei
背景和目标：表没食子儿茶素没食子酸酯（Epigallocatechin-3-gallat，EGCG）是绿色茶中的主要儿茶素，对人体重金属中毒具有潜在的保护作用。细胞凋亡是镉（Cd 2+）诱导细胞毒性的关键事件之一。然而，关于EGCG对Cd ~（2+）诱导的细胞凋亡的研究却鲜见报道。方法：正常人肝细胞（HL-7702）经Cd 2+处理21 h后，再与EGCG共同处理3 h，观察EGCG对Cd 2+诱导HL-7702细胞凋亡的影响。检测细胞存活率、凋亡率、细胞内活性氧（ROS）、丙二醛（MDA）、线粒体膜电位（MMP）和caspase-3活性。结果与结论：Cd ~（2+）可明显降低HL-7702细胞的存活率，诱导细胞凋亡。相反，EGCG共处理导致Cd 2+诱导的细胞活力和凋亡的减少的显着抑制，这意味着对Cd 2+中毒的EGCG的救援效果。保护作用最可能来自清除ROS和维持氧化还原稳态，因为细胞内ROS和MDA的产生被EGCG显著减少，这进一步防止MMP崩溃并抑制caspase-3活性。但在中性条件下，没有观察到EGCG与Cd ~（2+）的螯合作用。因此，从这项工作可以明确的结论，EGCG可以抑制镉2+诱导的细胞凋亡作为一个ROS清除剂，而不是金属螯合剂。
Context and objective: Epigallocatechin-3-gallat (EGCG), the major catechin in green tea, shows a potential protective effect against heavy metal toxicity to humans. Apoptosis is one of the key events in cadmium (Cd2+)-induced cytotoxicity. Nevertheless, the study of EGCG on Cd2+-induced apoptosis is rarely reported. The objective of this study was to clarify the effect and detailed mechanism of EGCG on Cd2+-induced apoptosis.Methods: Normal human liver cells (HL-7702) were treated with Cd2+ for 21 h, and then co-treated with EGCG for 3 h. Cell viability, apoptosis, intracellular reactive oxygen species (ROS), malondialdehyde (MDA), mitochondrial membrane potential (MMP) and caspase-3 activity were detected. On the other hand, the chelation of Cd2+ with EGCG was tested by UV-Vis spectroscopy analysis and Nuclear Magnetic Resonance (H-1 NMR) spectroscopy under neutral condition (pH 7.2).Results and conclusion: Cd2+ significantly decreased the cell viability and induced apoptosis in HL-7702 cells. Conversely, EGCG co-treatment resulted in significant inhibition of Cd2+-induced reduction of cell viability and apoptosis, implying a rescue effect of EGCG against Cd2+ poisoning. The protective effect most likely arises from scavenging ROS and maintaining redox homeostasis, as the generation of intracellular ROS and MDA is significantly reduced by EGCG, which further prevents MMP collapse and suppresses caspase-3 activity. However, no evidence is observed for the chelation of EGCG with Cd2+ under neutral condition. Therefore, a clear conclusion from this work can be made that EGCG could inhibit Cd2+-induced apoptosis by acting as a ROS scavenger rather than a metal chelating agent.