Classification of breast cancer cells on the basis of a functional assay for estrogen receptor
Classification of breast cancer cells on the basis of a functional assay for estrogen receptor
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DOI：
10.1007/bf03401751
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发表时间：
1998-07-01
影响因子：
5.7
通讯作者：
Pardee, AB
中科院分区：
文献类型：
--
作者：
Biswas, DK;Averboukh, L;Pardee, AB
背景资料：雌激素（E2）的受体（ER）通常作为一种标志物进行测定，以确定抗激素治疗乳腺癌的可行性，因为ER阳性（ER+）肿瘤比ER阴性（ER-）肿瘤更可能对抗激素治疗产生反应。然而，40%的ER+乳腺癌患者对抗激素治疗无反应。我们认为，这种不可预测性的治疗反应在于目前的ER检测，它只测量E2反应途径的初始成分，并且差异取决于改变下游过程。我们提出了一个功能标准，细分乳腺癌的基础上，ER的特异性结合其同源DNA序列，雌激素反应元件（ERE）。材料和方法：ER被确定在乳腺癌细胞系免疫荧光测定，Western印迹分析，识别ER特异性mRNA，并通过相互作用的ER-ERE复合物与三种不同的ER特异性抗体。电泳迁移率变动分析（EMSA）测定ER-ERE复合物的形成。结果：ER+ T47 D细胞对三苯氧胺、ICI-182，780和乙炔雌二醇（EE 2）敏感，而另一种ER+乳腺癌细胞系21 PT对这些化合物耐药。MCF-7和T47 D细胞核提取物中的雌激素受体（ER）与反应元件（ERE）以及E2反应性PS2启动子的下游反式激活表现出依赖性的相互作用。而在配体结合试验结果为ER-，其它ER试验结果均为ER+的21 PT细胞系中，ER-ERE相互作用和PS 2启动子反式激活均不依赖于激素。结论：根据ER-ERE相互作用的下游功能试验，ER+乳腺癌细胞可分为两类。第一种是E2依赖性（ERd+），这些细胞对抗激素治疗有反应。第二种类型的ER不依赖于E2（ER 1+）与ERE相互作用，并组成性地反式激活应答基因。据预测，后一种类型的乳腺癌对抗激素治疗没有反应。
Background: The receptor (ER) for estrogen (E2) is routinely assayed as a marker to determine the feasibility of anti-hormone therapy against breast cancer because ER-positive (ER+) tumors are much more likely to respond to anti-hormone therapy than are ER-negative (ER-). However 40% of ER+ breast cancer patients do not respond to anti-hormone therapy. We suggest that this unpredictability of therapeutic responses lies in the current ER assays, which measure only an initial component of the E2-responsive pathway, and that the difference depends upon altered downstream processes. We propose a functional criterion that subclassifies breast cancers on the basis of specific binding of ER to its cognate DNA sequence, the estrogen response element (ERE).Materials and Methods: ER was identified in breast cancer cell lines by immunofluorescence assay, Western blot analysis, identification of ER-specific mRNA, and by interaction of the ER-ERE complex with three different ER-specific antibodies. ER-ERE complex formation was measured by electrophoretic mobility shift assay (EMSA). Transactivation of the E2-responsive gene was studied by transfection of cells with fusion gene construct with the promoter-containing ERE sequence and assay of reporter gene activity in the cell extracts.Results: The growth of ER+ T47D cells was sensitive to tamoxifen, ICI-182,780, and ethynyl estradiol (EE2), whereas another ER+ breast cancer cell line, 21PT, was resistant to these compounds. The estrogen receptor (ER) in the nuclear extracts of MCF-7 and T47D demonstrated hormone-dependent interaction with the response element (ERE) and also downstream transactivation of the E2-responsive PS2 promoter. But in the 21PT cell line that was designated as ER- on the basis of ligand-binding assay and was found to be ER+ by all the other ER assays, ER-ERE interaction and PS2 promoter transactivation were independent of hormone.Conclusions: On the basis of the downstream functional assay of ER interaction with ERE, ER+ breast tumor cells can be subclassified into two categories. The first is E2-dependent (ERd+) and these cells should respond to anti-hormone therapy. The second type of ER interacts with ERE independent of E2 (ERi+) and constitutively transactivates responsive genes. It is predicted that the latter type of breast cancers will not respond to antihormone therapy.