目的：探讨细胞外信号调节激酶的上游激酶(MEK)抑制剂PD98059对H2O2诱导的人乳腺癌MCF-7细胞凋亡的影响及其作用机制。方法：H2O2诱导乳腺癌MCF-7细胞凋亡，PD98059干预其细胞凋亡。荧光染料吖啶橙(AO)观察细胞凋亡的形态学变化；流式细胞术法进行凋亡细胞计数；Western blot法检测p53，PCNA，caspase-3、caspase-9和Bcl-2的表达。结果：H2O2刺激细胞4 h、12 h，明显诱导了MCF-7细胞凋亡。PD98059将H2O2诱导的细胞凋亡率分别降低了约4％、14％，与H2O2刺激细胞12 h比较，具有显著的统计学差异(P < 0.05)。H2O2显著提高了p53蛋白的表达，激活了caspase-3与caspase-9蛋白，降低了Bcl-2的表达，而PD98059逆转了H2O2的刺激效应，下调了H2O2导致的p53与PCNA蛋白表达，降低了caspase-3与caspase-9蛋白活性，上调了Bcl-2蛋白表达。结论：MEK抑制剂PD98059抑制了H2O2诱导的MCF-7细胞凋亡，其作用机制与其降低了p53和PCNA蛋白表达和caspase-3与caspase-9蛋白活性以及增加Bcl-2蛋白表达有关。 Objective: to study the effect of MEK inhibitor of PD98059 on apoptosis induced by H2O2 and its mechanisms in human breast cancer MCF-7 cells. Methods: H2O2 inducing apoptosis in MCF-7 cells was set to observe apoptosis and its associated proteins treated in the present or absent of PD98059. The cellular morphology was investigated by AO staining. Apoptosis ratio was analyzed by flow cytometry. The expres-sions of p53, PCNA, caspase-3, caspase-9 and Bcl-2 were observed using Western blot analysis. Results: apoptosis was observed with cells treated H2O2 for 4 or 12 h while the degree of apoptosis was greatly de-creased by 4% or 14% in MCF-7 cells treated with H2O2 and PD98059 together. There was significantly dif-ference between with the treatment of H2O2 and PD98059 in the presence of H2O2 for 12 h (P < 0.05). The increased p53, activated caspase-3 and caspase-9 and decreased Bcl-2 were appeared with H2O2 treatment. However, the levels of p53 and PCNA were downregulated, the extent of caspase-3 and caspase-9 activation was decreased, and the level of Bcl-2 was upregulated in MCF-7 cells treated with PD98059 in the presence of H2O2. Conclusions: MEK inhibitor of PD98059 inhibited apoptosis by downregulating the levels of p53 and PCNA, decreasing the activation of caspase-3 and caspase-9 and upregulating the level of Bcl-2 in MCF-7 cells.
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