Laboratory of Genetics, Department of Biotechnology, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece.
Institute for Bioinnovation, Biomedical Sciences Research Center "Alexander Fleming", 34 Fleming Street, 16672 Vari, Greece.
J Med Chem. 2020 Oct 22;63(20):12043-12059. doi: 10.1021/acs.jmedchem.0c01316. Epub 2020 Oct 2.
Receptor activator of nuclear factor-κB ligand (RANKL) constitutes the master mediator of osteoclastogenesis, while its pharmaceutical inhibition by a monoclonal antibody has been approved for the treatment of postmenopausal osteoporosis. To date, the pursuit of pharmacologically more favorable approaches using low-molecular-weight inhibitors has been hampered by low specificity and high toxicity issues. This study aimed to discover small-molecule inhibitors targeting RANKL trimer formation. Through a systematic screening of 39 analogues of SPD-304, a dual inhibitor of tumor necrosis factor (TNF) and RANKL trimerization, we identified four compounds (, , , and ) that selectively inhibited RANKL-induced osteoclastogenesis in a dose-dependent manner, without affecting TNF activity or osteoblast differentiation. Based on structure-activity observations extracted from the most potent and less toxic inhibitors of RANKL-induced osteoclastogenesis, we synthesized a focused set of compounds that revealed three potent inhibitors (, and ) with remarkably low cell-toxicity and improved therapeutic indexes as shown by the LC to IC ratio. These RANKL-selective inhibitors are an excellent starting point for the development of small-molecule therapeutics against osteolytic diseases.
核因子-κB 受体激活剂配体 (RANKL) 是破骨细胞形成的主要介质，其单克隆抗体的药物抑制已被批准用于治疗绝经后骨质疏松症。迄今为止，使用低分子量抑制剂的药理学上更有利的方法的研究一直受到低特异性和高毒性问题的阻碍。本研究旨在发现针对 RANKL 三聚体形成的小分子抑制剂。通过对 TNF 和 RANKL 三聚化的双重抑制剂 SPD-304 的 39 种类似物进行系统筛选，我们鉴定出四种化合物（、、、和），它们能够以剂量依赖的方式选择性地抑制 RANKL 诱导的破骨细胞生成，而不影响 TNF 活性或成骨细胞分化。基于从 RANKL 诱导的破骨细胞生成的最有效和毒性较低的抑制剂中提取的结构活性观察结果，我们合成了一组具有针对性的化合物，揭示了三种有效的抑制剂（、和），具有极低的细胞毒性和改善的治疗指数，如 LC 到 IC 比值所示。这些 RANKL 选择性抑制剂是开发针对溶骨性疾病的小分子治疗药物的绝佳起点。
