三氧化二砷通过抑制IKK/NF-κB信号通路活化发挥促乳腺癌细胞凋亡效应

Arsenic trioxide induces apoptosis in MCF7 human breast cancer cells by inhibiting IKK/NF-κB pathway activation

目的探讨IKK/NF-κB信号通路在三氧化二砷(As2O3)诱导乳腺癌细胞凋亡反应中的作用。方法以乳腺癌细胞MCF7为靶细胞,以As2O3为刺激源,锥虫蓝(台盼蓝)拒染方法检测死亡细胞比率;双荧光素酶报告基因法检测MCF7细胞中NF-κB的活化状态;Western印迹方法检测IKK/NF-κB途径各信号分子的表达水平和活化状态;RT-PCR方法检测IKK/NF-κB途径下游靶基因的表达水平。结果 As2O3可显著诱导MCF7细胞凋亡;同时NF-κB的转录活化水平及其下游凋亡反应相关靶基因的表达水平也明显下降。在此过程中,I-κB的表达水平和NF-κB关键组成亚基(p65、p50)的核浆分布状态没有改变,但IKK激酶的两个催化亚基IKKα和IKKβ的表达水平明显下调。一过性高表达IKKα和IKKβ不仅能够恢复NF-κB的活化状态,而且能够拮抗As2O3诱导的乳腺癌细胞凋亡反应。结论 As2O3可通过在蛋白激酶水平抑制IKK/NF-κB信号通路活化从而发挥促乳腺癌细胞凋亡效应。

Objective To explore the role of IKK/NF-κB signaling pathway in mediating the apoptotic effect in human breast cancer cells exposed to arsenic trioxide（arsenite,As2O3）.Methods MCF7 cells were treated with arsenite.Cell death was detected by phenol blue staining.Luciferase assay was used to detect the transactivation status of NF-κB in the MCF7 cells.The expression levels of IKKα,IKKβ,I-κB and the cytoplasmic/nuclear distribution of p65 and p50 were detected by Western blotting.The expression levels of NF-κB downstream target genes were determined by RT-PCR. Results Arsenite induced apoptosis in MCF7 cells,along with significant inhibition of NF-κB transactivation and NF-κB target genes expression.Interestingly,the expression level of I-κB and cytoplasmic/nuclear distribution of p65 and p50 were not altered,but both IKKα and IKKβ levels were dramatically down-regulated under the same conditions.Moreover,overexpressed IKKα or IKKβ recovered NF-κB transactivation,and antagonized arsenite-induced apoptotic response in MCF7 cells.Conclusion Arsenite induces apoptosis in MCF7 cells by inhibiting IKKs expression and the subsequent NF-κB transactivation.