A new class of small molecule estrogen receptor-alpha antagonists that overcome anti-estrogen resistance.
A new class of small molecule estrogen receptor-alpha antagonists that overcome anti-estrogen resistance.
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DOI：
10.18632/oncotarget.6323
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发表时间：
2015-12-01
期刊：
影响因子：
--
通讯作者：
Rosen EM
中科院分区：
文献类型：
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作者：
Ma Y;Preet A;Tomita Y;De Oliveira E;Zhang L;Ueda Y;Clarke R;Brown M;Rosen EM
先前的研究表明BRCA 1蛋白与雌激素受体α（ER）结合并抑制其活性。在这里，我们发现BRCA 1过表达不仅抑制抗雌激素抗性LCC 9细胞中的ER活性，而且部分恢复了它们对他莫昔芬的敏感性。为了模拟BRCA 1在他莫昔芬耐药背景下抑制ER的机制，我们在ER/他莫昔芬复合物内创建了BRCA 1结合空腔的三维模型;我们筛选了药效团数据库以识别可以装入该空腔的小分子。在前40个“命中”中，6个在抗雌激素敏感的MCF-7细胞中表现出有效的ER抑制活性，6个中的4个在LCC 9细胞中表现出相似的活性（IC 50 ≤ 1.0 μM）。通过突变分析验证了模型的有效性。两种代表性化合物（4631-P/1和35466-L/1）抑制他莫昔芬抗性细胞（LCC 9和LCC 2）中的ER依赖性细胞增殖，并部分恢复对他莫昔芬的敏感性。这些化合物还破坏了BRCA 1与ER的结合。在电泳迁移率变动分析中，化合物导致ER从模型雌激素反应元件中解离。最后，化合物35446的修饰形式（盐酸盐）在无毒浓度下抑制LCC 9肿瘤异种移植物的生长。这些结果确定了一组新的小分子，可以克服他莫昔芬耐药性。
Previous studies indicate that BRCA1 protein binds to estrogen receptor-alpha (ER) and inhibits its activity. Here, we found that BRCA1 over-expression not only inhibits ER activity in anti-estrogen-resistant LCC9 cells but also partially restores their sensitivity to Tamoxifen. To simulate the mechanism of BRCA1 inhibition of ER in the setting of Tamoxifen resistance, we created a three-dimensional model of a BRCA1-binding cavity within the ER/Tamoxifen complex; and we screened a pharmacophore database to identify small molecules that could fit into this cavity. Among the top 40 “hits”, six exhibited potent ER inhibitory activity in anti-estrogen-sensitive MCF-7 cells and four of the six exhibited similar activity (IC50 ≤ 1.0 μM) in LCC9 cells. We validated the model by mutation analysis. Two representative compounds (4631-P/1 and 35466-L/1) inhibited ER-dependent cell proliferation in Tamoxifen-resistant cells (LCC9 and LCC2) and partially restored sensitivity to Tamoxifen. The compounds also disrupted the association of BRCA1 with ER. In electrophoretic mobility shift assays, the compounds caused dissociation of ER from a model estrogen response element. Finally, a modified form of compound 35446 (hydrochloride salt) inhibited growth of LCC9 tumor xenografts at non-toxic concentrations. These results identify a novel group of small molecules that can overcome Tamoxifen resistance.