Abstract:

Objective To explore effects of epigallocatechin-3-gallate (EGCG) on proliferation and apoptosis of human gastric cancer cell line SGC7901 under hypoxia and its mechanism. Methods The SGC7901 cells were subcultured. Hypoxic model was established by Cobalt Chloride (CoCl2). SGC7901 cells were divided into different groups: control group, hypoxia control group, and hypoxia combined with different concentrations of EGCG groups. The proliferation of SGC7901 cells in different groups was determined by MTT and the apoptosis was analyzed by flow cytometry (FCM). Besides, RT-PCR and Western blotting were used to detect the expressions of hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor-A (VEGF-A) in the cells.ResultsLower concentrations of EGCG had no obvious effects on the proliferation of SGC7901 cells in short time under hypoxia (P>0.05). But with higher dose or longer time, EGCG could further inhibit the proliferation of SGC7901 cells under hypoxia (P<0.01). And the inhibition rate reached （76.3±2.9）% after treatment with 100 μg/mL EGCG for 72 h. FCM results revealed that EGCG induced the apoptosis of SGC7901 cells in a dose- and time-dependent manner (P<0.05 or P<0.01). EGCG could reduce obviously the protein levels of HIF-1α and VEGF-A induced by hypoxia (P<0.05 or P<0.01), and down-regulate the expression of VEGF-A mRNA (P<0.05 or P<0.01), but had no obvious effect on the transcription of HIF-1α (P>0.05). Conclusion EGCG inhibits the proliferation of SGC7901 cells and induces the apoptosis of these cells under hypoxia. These effects may have relationship with the down-regulation of HIF-1α and VEGF-A, which was induced by hypoxia.

Key words: epirigallocatechin-3-gallate, hypoxia, gastric cancer cell, apoptosis, hypoxia inducible factor-1 alpha, vascular endothelial growth factor-A