Shoda Takuji, Kato Masashi, Fujisato Takuma, Demizu Yosuke, Inoue Hideshi, Naito Mikihiko, Kurihara Masaaki
National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
Med Chem. 2017;13(3):206-213. doi: 10.2174/1573406412666160805101408.
Estrogen receptors (ERs) are an important target for the management of breast cancers. Selective estrogen receptor down-regulators (SERDs) block ER activity, as well as reduce ERα protein levels in cells, and therefore are promising therapeutic agents for the treatment of breast cancers.
In order to develop potent SERDs, we prepared tamoxifen and fulvestrant hybrids and evaluated their binding activity and down-regulation of ERα.
We designed and synthesized tamoxifen derivatives, which had a 4,4,5,5,5- pentafluoropentyl group on the terminal alkyl chain. The oxidation state of the sulfur atom and alkyl length between the sulfur and nitrogen atoms were varied. Western blotting was performed to determine the ability to down-regulate ERα. Binding affinities of synthesized compounds were evaluated by a fluorescence polarization-based competitive binding assay.
We successfully prepared nine compounds. Treatment with 11, 14, and 17 effectively reduced ERα protein levels in MCF-7 cells in a concentration-dependent manner. This reduction was inhibited by a proteasome inhibitor. The ability of 14 to down-regulate the ERα protein level was equal to fulvestrant. All compounds showed a largely equal affinity for ERα.
As indicated by Western blots, the ERα degradation activity was observed only in the series of butyl linker derivatives, namely, 11, 14, and 17. These findings suggest that the specific length of the alkyl chain is an important factor in controlling the down-regulation of ER. These results provide useful information for designing promising SERD candidates.
雌激素受体（ERs）是乳腺癌治疗的重要靶点。选择性雌激素受体下调剂（SERDs）可阻断ER活性，并降低细胞中ERα蛋白水平，因此是治疗乳腺癌的有前景的治疗药物。
为了开发强效SERDs，我们制备了他莫昔芬和氟维司群的杂合物，并评估了它们与ERα的结合活性和下调作用。
我们设计并合成了在末端烷基链上带有4,4,5,5,5-五氟戊基的他莫昔芬衍生物。硫原子的氧化态以及硫原子和氮原子之间的烷基长度有所变化。通过蛋白质免疫印迹法测定下调ERα的能力。通过基于荧光偏振的竞争性结合试验评估合成化合物的结合亲和力。
我们成功制备了9种化合物。用11、14和17处理可有效降低MCF-7细胞中ERα蛋白水平，且呈浓度依赖性。这种降低被蛋白酶体抑制剂抑制。14下调ERα蛋白水平的能力与氟维司群相当。所有化合物对ERα的亲和力大致相同。
如蛋白质免疫印迹所示，仅在丁基连接体衍生物系列（即11、14和17）中观察到ERα降解活性。这些发现表明，烷基链的特定长度是控制ER下调的重要因素。这些结果为设计有前景的SERD候选物提供了有用信息。
