Transcriptional regulation of estrogen receptor-alpha by p53 in human breast cancer cells.
Transcriptional regulation of estrogen receptor-alpha by p53 in human breast cancer cells.
复制标题
DOI：
10.1158/0008-5472.can-08-3628
复制
发表时间：
2009-04-15
期刊：
影响因子：
11.2
通讯作者：
Fuchs-Young R
中科院分区：
文献类型：
--
作者：
Shirley SH;Rundhaug JE;Tian J;Cullinan-Ammann N;Lambertz I;Conti CJ;Fuchs-Young R
雌激素受体α (ER)和p53是乳腺癌预后的重要指标。功能p53缺失与预后不良、ER阴性和抗雌激素治疗抵抗相关。此前，我们发现p53基因型与MMTV-Wnt-1转基因小鼠乳腺肿瘤中ER表达和他莫昔芬应答相关。这些结果使我们假设p53可能调节ER的表达。为了验证这一点，用阿霉素或电离辐射处理MCF-7细胞，这两种方法都能刺激p53表达增加5倍。ER表达在24小时内也增加了4倍。在用靶向p53的siRNA处理的细胞中，在24小时内，p53和ER的表达均显著降低（约60%）。dna损伤剂对ER的诱导依赖于p53，因为IR或dox在用靶向p53的siRNA处理后都不能上调ER。为了进一步研究p53是否直接调控ER基因启动子的转录，我们将野生型（WT） p53表达载体与含有ER近端启动子的荧光素酶报告基因一起瞬时转染MCF-7细胞。在转染了WT p53的细胞中，ER启动子的转录增加了8倍。染色质免疫沉淀实验显示，p53与CARM1、CBP、c-Jun和Sp1一起被募集到ER启动子中，并且这种多因子复合物以p53依赖的方式形成。这些数据表明，p53通过对ER启动子的转录控制来调节ER的表达，这解释了它们在人类乳腺癌中的一致表达。
Estrogen receptor α (ER) and p53 are critical prognostic indicators in breast cancer. Loss of functional p53 is correlated with poor prognosis, ER negativity and resistance to antiestrogen treatment. Previously, we found that p53 genotype was correlated with ER expression and response to tamoxifen in mammary tumors arising in MMTV-Wnt-1 transgenic mice. These results lead us to hypothesize that p53 may regulate ER expression. To test this, MCF-7 cells were treated with doxorubicin or ionizing radiation, both of which stimulated a 5-fold increase in p53 expression. ER expression was also increased 4-fold over a 24 hour time frame. In cells treated with siRNA targeting p53, expression of both p53 and ER was significantly reduced (>60%) by 24 hours. Induction of ER by DNA-damaging agents was p53-dependent as either IR or dox failed to upregulate ER after treatment with p53-targeting siRNA. To further investigate whether p53 directly regulates transcription of the ER gene promoter, MCF-7 cells were transiently transfected with a wild type (WT) p53 expression vector along with a luciferase reporter containing the proximal promoter of ER. In cells transfected with WT p53, transcription from the ER promoter was increased 8-fold. Chromatin immunoprecipitation assays showed that p53 was recruited to the ER promoter along with CARM1, CBP, c-Jun and Sp1 and that this multifactor complex was formed in a p53-dependent manner. These data demonstrate that p53 regulates ER expression through transcriptional control of the ER promoter, accounting for their concordant expression in human breast cancer.