Vancouver Prostate Centre, Department of Urologic Science, University of British Columbia, 2660 Oak Street, Vancouver, BC, V6H 3Z6, Canada.
Department of Chemistry, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.
Breast Cancer Res. 2024 Nov 26;26(1):168. doi: 10.1186/s13058-024-01926-2.
Up to 40% of patients with estrogen receptor (ER)-positive breast cancer will develop resistance against the majority of current ER-directed therapies. Resistance can arise through various mechanisms such as increased expression levels of coregulators, and key mutations acquired in the receptor's ligand binding domain rendering it constitutively active. To overcome these resistance mechanisms, we explored targeting the ER Activation Function 2 (AF2) site, which is essential for coactivator binding and activation. Using artificial intelligence and the deep docking methodology, we virtually screened > 1 billion small molecules and identified 290 potential AF2 binders that were then characterized and validated through an iterative screening pipeline of cell-based and cell-free assays. We ranked the compounds based on their ability to reduce the transcriptional activity of the estrogen receptor and the viability of ER-positive breast cancer cells. We identified a lead compound, VPC-260724, which inhibits ER activity at low micromolar range. We confirmed its direct binding to the ER-AF2 site through a PGC1α peptide displacement experiment. Using proximity ligation assays, we showed that VPC-260724 disrupts the interaction between ER-AF2 and the coactivator SRC-3 and reduces the expression of ER target genes in various breast cancer models including the tamoxifen resistant cell line TamR3. In conclusion, we developed a novel ER-AF2 binder, VPC-260724, which shows antiproliferative activity in ER-positive breast cancer models. The use of an ER-AF2 inhibitor in combination with current treatments may provide a novel complementary therapeutic approach to target treatment resistance in ER-positive breast cancer.
多达 40%的雌激素受体 (ER)-阳性乳腺癌患者将对大多数当前的 ER 靶向治疗产生耐药性。耐药性可能通过多种机制产生，例如共调节剂表达水平增加，以及受体配体结合域中获得的关键突变使其持续激活。为了克服这些耐药机制，我们探索了靶向 ER 激活功能 2 (AF2) 位点，该位点对于共激活剂结合和激活至关重要。我们使用人工智能和深对接方法，虚拟筛选了超过 10 亿种小分子，并鉴定出 290 种潜在的 AF2 结合物，然后通过基于细胞和无细胞测定的迭代筛选管道对其进行表征和验证。我们根据化合物降低雌激素受体转录活性和 ER 阳性乳腺癌细胞活力的能力对化合物进行排名。我们确定了一种先导化合物 VPC-260724，它以低微摩尔范围抑制 ER 活性。我们通过 PGC1α 肽置换实验证实了它直接结合 ER-AF2 位点。通过邻近连接测定，我们表明 VPC-260724 破坏了 ER-AF2 与共激活剂 SRC-3 之间的相互作用，并降低了各种乳腺癌模型中 ER 靶基因的表达，包括他莫昔芬耐药细胞系 TamR3。总之，我们开发了一种新型的 ER-AF2 结合物 VPC-260724，它在 ER 阳性乳腺癌模型中显示出抗增殖活性。在 ER 阳性乳腺癌中，使用 ER-AF2 抑制剂与当前治疗联合使用可能为靶向治疗耐药性提供一种新的互补治疗方法。
