Mishra Sandip K, Balasenthil Seetharaman, Nguyen Diep, Vadlamudi Ratna K
Department of Molecular and Cellular Oncology, Unit 108, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA.
Gene. 2004 Apr 14;330:115-22. doi: 10.1016/j.gene.2004.01.011.
Proline-, glutamic acid- and leucine-rich protein 1 (PELP1)/modulator of nongenomic activity of estrogen receptor (MNAR), a novel coactivator of estrogen receptors (ERs; ERalpha and ERbeta), modulates the genomic and nongenomic functions of the ERs. PELP1 expression is developmentally regulated in mammary glands and overexpressed in breast tumors. However, little is known about the regulation of PELP1. In this study, we examined whether PELP1 expression is modulated by steroid hormone 17beta-estradiol (E2)-ER pathway. We found that in MCF-7 breast cancer cells, E2 upregulated PELP1 expression threefold and that this upregulation was reduced by antiestrogen. We also found that E2 modulated PELP1 levels in an actinomycin-D-sensitive manner, suggesting transcriptional regulation. Cloning and analysis of the 2-kb PELP1 promoter region revealed two estrogen-responsive element (ERE) half sites in the PELP1 promoter region. In transient transfection assays, E2 upregulated PELP1 promoter activity in breast, endometrial and osteosarcoma model cancer cell lines in an ICI 182,780-sensitive manner. We demonstrated the recruitment of ER to the PELP1 promoter in vitro using EMSA assays and in vivo using a chromatin immunoprecipitation assay. The PELP1 promoter was similarly upregulated by both ERalpha and ERbeta and differentially regulated by selective estrogen receptor modulators in a cell line-dependent manner. Our results suggest that PELP1 expression is modulated by the E2-ER pathway and that PELP1 is an ER target gene.
富含脯氨酸、谷氨酸和亮氨酸的蛋白1（PELP1）/雌激素受体非基因组活性调节剂（MNAR）是雌激素受体（ERs；ERα和ERβ）的一种新型共激活因子，可调节ERs的基因组和非基因组功能。PELP1的表达在乳腺中受到发育调控，且在乳腺肿瘤中过表达。然而，关于PELP1的调控机制知之甚少。在本研究中，我们检测了PELP1的表达是否受甾体激素17β-雌二醇（E2）-ER途径的调节。我们发现，在MCF-7乳腺癌细胞中，E2使PELP1的表达上调了三倍，且这种上调可被抗雌激素药物降低。我们还发现，E2以对放线菌素-D敏感的方式调节PELP1的水平，提示存在转录调控。对2 kb的PELP1启动子区域进行克隆和分析，发现在PELP1启动子区域有两个雌激素反应元件（ERE）半位点。在瞬时转染实验中，E2以ICI 182,780敏感的方式上调了乳腺、子宫内膜和骨肉瘤模型癌细胞系中PELP1启动子的活性。我们通过电泳迁移率变动分析（EMSA）实验在体外以及通过染色质免疫沉淀实验在体内证明了ER被招募到PELP1启动子上。PELP1启动子同样被ERα和ERβ上调，且在不同细胞系中受到选择性雌激素受体调节剂的差异性调控。我们的结果表明，PELP1的表达受E2-ER途径的调节，且PELP1是一个ER靶基因。
