EGCG对阿霉素诱导的胃癌细胞MKN28衰老的影响

Treatment with EGCG promotes doxorubicin-induced cell senescence in gastric cancer cell line MKN28

目的:观察表没食子儿茶素没食子酸酯[(-)-epigallocatechin-3-gallate,EGCG)]对阿霉素诱导的胃癌细胞MKN28衰老的影响.方法:Western blot检测EGCG对EZH2蛋白表达的影响;阿霉素诱导经EGCG处理的MKN28细胞衰老,衰老相关--半乳糖苷酶(senescence associated--galactosidase,SA--gal)染色检测各组细胞衰老情况,激光共聚焦显微镜检测各组细胞核中衰老相关异染色质灶(senescence-associated heterochromatic foci,SAHF)的形成;噻唑蓝比色法(MTT)和流式细胞术检测EGCG对MKN28细胞生长和周期的影响,并比较在阿霉素诱导下各组细胞的相应变化.结果:EGCG可明显抑制EZH2蛋白表达,经EGCG处理的MKN28细胞在阿霉素诱导下SA--gal染色阳性率和SAHF形成比例明显高于阿霉素组和EGCG组,分别为72.16%±4.03%、34.42%±7.06%、15.40%±1.70%和86.44%±4.33%、47.73%±3.03%、80.28%±1.24%;与空白对照组相比,经不同浓度EGCG处理的MKN28细胞其周期G0/G1比例以及生长抑制率会随浓度的增高而增大(P<0.05),在阿霉素的诱导下此趋势更为明显.结论:EGCG可通过抑制EZH2表达来促进阿霉素对MKN28细胞的衰老诱导作用.

AIM： To investigate the effect of treatment with （-）-epigallocatechin-3-gallate （EGCG） on EZH2 expression and doxorubicin-induced cell senescence in gastric cancer cell line MKN28. METHODS： MKN28 cells were treated with EGCG in the presence or absence of doxorubicin. Protein expression of EZH2 was detected by Western blot. Doxorubicin-induced senescence of MKN28 cells was analyzed by senescenceassociated β-galactosidase （SA-β-gal） staining. The formation of senescence-associated heterochromatic foci （SAHF） was measured by laser confocal microscopy. Cell cycle progression and cell proliferation of treated MKN28 cells were measured by flow cytometry and MTT assay, respectively. RESULTS： EGCG effectively suppressed the expression of EZH2 protein and promoted doxorubicin-induced cell senescence and formation of SAHF in MKN28 cells. In the EGCG ＋ doxorubicin group, the percentages of cells positive for SA-β-gal and SAHF formation proportion were increased more significantly than those in the doxorubicin group and EGCG group （72.16% ± 4.03% vs 34.42% ± 7.06%, 15.40% ± 1.70%; 86.44% ± 4.33% vs 47.73% ± 3.03%, 80.28% ± 1.24%）. In EGCG-treated MKN28 cells, the proportion of cells in G0 /G1 phase and reduced rate of cell proliferation increased with the increase in the concentration of EGCG, and this effect was more notable in the presence of doxorubicin. CONCLUSION： EGCG can effectively suppress the expression of EZH2 and therefore promote doxorubicin-induced cell senescence in MKN28 cells.