The Green Tea Component (-)-Epigallocatechin-3-Gallate Sensitizes Primary Endothelial Cells to Arsenite-Induced Apoptosis by Decreasing c-Jun N-Terminal Kinase-Mediated Catalase Activity

Abstract

The green tea component (-)-epigallocatechin-3-gallate (EGCG) has been shown to sensitize many different types of cancer cells to anticancer drug-induced apoptosis, although it protects against non-cancerous primary cells against toxicity from certain conditions such as exposure to arsenic (As) or ultraviolet irradiation. Here, we found that EGCG promotes As-induced toxicity of primary-cultured bovine aortic endothelial cells (BAEC) at doses in which treatment with each chemical alone had no such effect. Increased cell toxicity was accompanied by an increased condensed chromatin pattern and fragmented nuclei, cleaved poly(ADP-ribose) polymerase (PARP), activity of the pro-apoptotic enzymes caspases 3, 8 and 9, and Bax translocation into mitochondria, suggesting the involvement of an apoptotic signaling pathway. Fluorescence activated cell sorting analysis revealed that compared with EGCG or As alone, combined EGCG and As (EGCG/As) treatment significantly induced production of reactive oxygen species (ROS), which was accompanied by decreased catalase activity and increased lipid peroxidation. Pretreatment with N-acetyl-L-cysteine or catalase reversed EGCG/As-induced caspase activation and EC toxicity. EGCG/As also increased the phosphorylation of c-Jun N-terminal kinase (JNK), which was not reversed by catalase. However, pretreatment with the JNK inhibitor SP600125 reversed all of the observed effects of EGCG/As, suggesting that JNK may be the most upstream protein examined in this study. Finally, we also found that all the observed effects by EGCG/As are true for other types of EC tested. In conclusion, this is firstly to show that EGCG sensitizes non-cancerous EC to As-induced toxicity through ROS-mediated apoptosis, which was attributed at least in part to a JNK-activated decrease in catalase activity.

Recent Advances in Anticancer Activities and Drug Delivery Systems of Tannins

“…Pretreatment with EGCG dose‐dependently reduced IR‐induced expression of survivin leading to significantly increased radiosensitivity and decreased cell proliferation . However, EGCG made bortezomib less effective by an autophagy mechanism and promoted arsenite‐induced toxicity in primary‐cultured bovine aortic endothelial cells, suggesting that green tea products should be contraindicated during bortezomib or arsenite therapy . Furthermore, the doses of the combination of EGCG and anticancer drugs have been shown in Table , which demonstrated that EGCG at low doses (about 5 μM) might have the chemoprotective effect combining with anticancer agents (such as doxorubicin).…”

Antioxidants Protect against Arsenic Induced Mitochondrial Cardio-Toxicity

“…Arsenic, a recognized cardiovascular toxicant, has exhibited mito-toxic effects in vascular smooth muscle [ 44 ], myocardial cells [ 45 ], and vascular endothelial cells [ 46 ]. Arsenic is associated with mitochondrial dysfunction through mechanisms such as elevated ROS, induction of apoptosis, and Ca 2+ overload.…”

Inhibition of Nickel Nanoparticles-Induced Toxicity by Epigallocatechin-3-Gallate in JB6 Cells May Be through Down-Regulation of the MAPK Signaling Pathways

“…EGCG is a major component of polyphenols in green tea [ 14 , 15 ]. It has inhibitory effects on cell transformation and early cancerization, ROS generation and DNA damage induced by inflammation [ 16 , 17 ].…”