Estrogen receptor α (ERα) is an important target for the design of drugs such as tamoxifen (2a) and fulvestrant (5). Three series of ER-ligands based on the benzoxepin scaffold structure were synthesized: series I containing an acrylic acid, series II with an acrylamide, and series III with a saturated carboxylic acid substituent. These compounds were shown to be high affinity ligands for the ER with nanomolar IC₅₀ binding values. Series I acrylic acid ligands were generally ERα selective. In particular, compound 13e featuring a phenylpenta-2,4-dienoic acid substituent was shown to be antiproliferative and downregulated ERα and ERβ expression in MCF-7 breast cancer cells. Interestingly, from series III, the phenoxybutyric acid derivative compound 22 was not antiproliferative and selectively downregulated ERβ. A docking study of the benzoxepin ligands was undertaken. Compound 13e is a promising lead for development as a clinically relevant SERD, while compound 22 will be a useful experimental probe for helping to elucidate the role of ERβ in cancer cells.

中文翻译：

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具有亚型特异性 ERα 和 ERβ 活性的苯并塞平型选择性雌激素受体 (ER) 调节剂和下调剂的先导优化

雌激素受体 α (ERα) 是他莫昔芬 ( 2a ) 和氟维司群 ( 5 )等药物设计的重要目标。合成了三个系列的基于苯并氧杂环酯支架结构的 ER 配体：系列 I 含有丙烯酸，系列 II 具有丙烯酰胺，系列 III 具有饱和羧酸取代基。这些化合物被证明是具有纳摩尔 IC ₅₀结合值的 ER 的高亲和力配体。I 系列丙烯酸配体通常具有 ERα 选择性。特别是化合物13e以苯基五-2,4-二烯酸取代基为特征的研究表明，在 MCF-7 乳腺癌细胞中具有抗增殖和下调 ERα 和 ERβ 表达的作用。有趣的是，从系列 III 中，苯氧基丁酸衍生化合物22不具有抗增殖作用，并且选择性下调 ERβ。进行了苯并恶平配体的对接研究。化合物13e是作为临床相关 SERD 开发的有前景的先导物，而化合物22将成为有助于阐明 ERβ 在癌细胞中作用的有用实验探针。