ATM and p53 regulate FOXM1 expression via E2F in breast cancer epirubicin treatment and resistance.
ATM and p53 regulate FOXM1 expression via E2F in breast cancer epirubicin treatment and resistance.
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DOI：
10.1158/1535-7163.mct-11-0024
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发表时间：
2011-06
影响因子：
5.7
通讯作者：
Lam EW
中科院分区：
文献类型：
--
作者：
Millour J;de Olano N;Horimoto Y;Monteiro LJ;Langer JK;Aligue R;Hajji N;Lam EW
在这份报告中，我们研究了FOXM 1在乳腺癌和表阿霉素耐药中的作用和调节。我们产生了表阿霉素耐药的MCF-7乳腺癌（MCF-7-EPIR）细胞，并发现与MCF-7细胞相比，MCF-7-EPIR中的FOXM 1蛋白水平更高，并且FOXM 1表达在MCF-7中被表阿霉素下调，但在MCF-7-EPIR细胞中没有。我们还确定了MCF-7-EPIR细胞中p53功能的丧失，并且表柔比星通过激活MCF-7细胞中的p53和抑制E2 F活性来抑制转录和基因启动子水平的FOXM 1表达。使用p53-/- MEFs，我们发现p53对表阿霉素敏感性很重要。此外，瞬时启动子转染试验表明，表阿霉素及其细胞效应子p53和E2 F1通过位于近端启动子区域内的E2 F结合位点调节FOXM 1转录。染色质免疫沉淀分析还显示，表阿霉素处理增加pRB和减少E2 F1募集到FOXM 1启动子区含有E2 F位点。我们还发现，与MCF-7细胞相比，耐药MCF-7-EPIR细胞中的共济失调-毛细血管扩张突变（ATM）蛋白和mRNA过表达，表阿霉素可以激活ATM以促进E2 F活性和FOXM 1表达。此外，用咖啡因抑制U2 OS细胞中的ATM或用siRNA耗尽MCF-7-EPIR中的ATM可以使这些抗性细胞对表阿霉素重新敏感，导致E2 F1和FOXM 1表达下调和细胞死亡。总之，我们的数据显示ATM和p53通过E2 F协同调节FOXM 1，从而调节乳腺癌的表阿霉素反应和抗性。
In this report we investigated the role and regulation of FOXM1 in breast cancer and epirubicin resistance. We generated epirubicin resistant MCF-7 breast carcinoma (MCF-7-EPIR) cells and found FOXM1 protein levels to be higher in MCF-7-EPIR compared to MCF-7 cells, and that FOXM1 expression is down-regulated by epirubicin in MCF-7 but not in MCF-7-EPIR cells. We also established that there is a loss of p53 function in MCF-7-EPIR cells and that epirubicin represses FOXM1 expression at transcription and gene promoter levels through activation of p53 and repression of E2F activity in MCF-7 cells. Using p53-/- MEFs, we showed that p53 is important for epirubicin sensitivity. Moreover, transient promoter transfection assays demonstrated that epirubicin and its cellular effectors p53 and E2F1 modulate FOXM1 transcription through an E2F-binding site located within the proximal promoter region. Chromatin immunoprecipitation analysis also revealed that epirubicin treatment increases pRB and decreases E2F1 recruitment to the FOXM1 promoter region containing the E2F-site. We also found Ataxia-telangiectasia mutated (ATM) protein and mRNA to be overexpressed in the resistant MCF-7-EPIR cells compared to MCF-7 cells and that epirubicin can activate ATM to promote E2F activity and FOXM1 expression. Furthermore, inhibition of ATM in U2OS cells with caffeine or depletion of ATM in MCF-7-EPIR with siRNAs can re-sensitise these resistant cells to epirubicin, resulting in down-regulation of E2F1 and FOXM1 expression and cell death. In summary, our data show that ATM and p53 coordinately regulate FOXM1 via E2F to modulate epirubicin response and resistance in breast cancer.