Epigallocatechin-3-gallate Enhances Ischemia/Reperfusion-induced Apoptosis In Human Umbilical Vein Endothelial Cells Via AKT And MAPK Pathways

Objective:Endothelial cells play a pivotal role in preserving vascular integrity and preventing thrombosis. Endothelial dysfunction is one of the most common pathological changes and contributes significantly to subsequent functional and cellular injury in cardiovascular diseases. Endothelial cells appear to be one of the primary targets for ischemia/reperfusion (I/R). Green tea is a popular beverage cons?Med worldwide. Epigallocatechin-3-gallate (EGCG), a major constituent of green tea, has been shown to possess marked biological activities, such as anti-oxidant, anti-mutagenic, antiproliferative and pro-apoptotic effects in a variety of experimental models.We sought to investigate whether treatment with EGCG modulates I/R-induced cell proliferation arrest, apoptosis and the signaling pathway events in endothelial cells.Methods:HUVECs were treated with or without EGCG (dissolved in H2O) for 0.5 h and then exposed to simulated ischemia solution equilibrated with 95%N2 and 5% CO2. After 4 h of ischemia, reperfusion was initiated by replacement of normal cell medi?M in the presence or absence of EGCG under normoxic conditions for different time points. The apoptosis was measured by TUNEL assay. The protein levels were determined by western blotting. Cell proliferation was measured using WST-1 assay.Results:1. EGCG is able to regulate cycle-related effectors as well as inhibit endothelial cell growth after simulated I/R injury. 2. Treatment of HUVECs with EGCG significantly increased l/R-induced the expression of cleaved caspase-3 and PARP in a time-dependent manner, and this change was coincided with a marked increase in l/R-induced apoptotic cell death.3. EGCG can enhance l/R-induced apoptosis of HUVECs via regulating the expression of Bcl-2 family proteins and the activation of mitochondrial apoptotic pathway.4. EGCG increases l/R-induced apoptosis in HUVECs through inactivation of AKT and ERK signaling pathways, activation of JNK1/2 signaling pathway.Conclusion:EGCG enhanced l/R-induced apoptosis of HUVECs in a time-and dose-dependent manner.The PI3K/AKT, MEK/ERK and JNK pathways may be essential for EGCG-induced apoptosis in HUVECs in response to I/R injury.