Abdel-Rahman Somaya A, Świderek Katarzyna, Gabr Moustafa T
Department of Radiology, Molecular Imaging Innovations Institute (MI3), Weill Cornell Medicine New York NY 10065 USA
Department of Medicinal Chemistry, Faculty of Pharmacy, Mansoura University Mansoura 35516 Egypt.
RSC Med Chem. 2023 Aug 1;14(9):1767-1777. doi: 10.1039/d3md00150d. eCollection 2023 Sep 19.
The interaction of the inducible co-stimulator (ICOS) with its ligand (ICOSL) plays key roles in T-cell differentiation and activation of T-cell to B-cell functions. The ICOS/ICOSL pathway is a validated target for T-cell lymphomas induced by the proliferation of T-follicular helper (Tfh) cells. Moreover, the inhibition of ICOS/ICOSL interaction can decrease the enhancement of immunosuppressive regulatory T cells (Tregs) in both hematologic malignancies and solid tumors. However, targeting ICOS/ICOSL interaction is currently restricted to monoclonal antibodies (mAbs) and there are no small molecules in existence that can block ICOS/ICOSL. To fill this gap, we report herein the first time-resolved fluorescence resonance energy transfer (TR-FRET) assay to evaluate the ability of small molecules to inhibit ICOS/ICOSL interaction. Implementation of the developed TR-FRET assay in high-throughput screening (HTS) of a focused chemical library resulted in the identification of as a first-in-class inhibitor of ICOS/ICOSL interaction. We further employed docking studies and molecular dynamics (MD) simulations to identify the plausible mechanism of blocking ICOS/ICOSL complex formation by . Using the structure-activity relationship (SAR) by catalog approach, we identified with an IC value of 4.68 ± 0.47 μM in the ICOS/ICOSL TR-FRET assay. Remarkably, revealed a dose-dependent ability to block ICOS/ICOSL interaction in a bioluminescent cellular assay based on co-culturing Jurkat T cells expressing ICOS and CHO-K1 cells expressing ICOSL. This work will pave the way for future drug discovery efforts aiming at the development of small molecule inhibitors of ICOS/ICOSL interaction as potential therapeutics for cancer as well as other diseases.
诱导性共刺激分子（ICOS）与其配体（ICOSL）的相互作用在T细胞分化以及T细胞对B细胞功能的激活中发挥着关键作用。ICOS/ICOSL信号通路是由T滤泡辅助细胞（Tfh）增殖诱导的T细胞淋巴瘤的一个已验证靶点。此外，抑制ICOS/ICOSL相互作用可减少血液系统恶性肿瘤和实体瘤中免疫抑制性调节性T细胞（Tregs）的增强。然而，目前针对ICOS/ICOSL相互作用的靶向治疗仅限于单克隆抗体（mAb），尚无能够阻断ICOS/ICOSL的小分子。为填补这一空白，我们在此首次报道了一种时间分辨荧光共振能量转移（TR-FRET）测定法，用于评估小分子抑制ICOS/ICOSL相互作用的能力。在聚焦化学文库的高通量筛选（HTS）中实施所开发的TR-FRET测定法，结果鉴定出一种作为ICOS/ICOSL相互作用的一流抑制剂。我们进一步采用对接研究和分子动力学（MD）模拟来确定该抑制剂阻断ICOS/ICOSL复合物形成的可能机制。通过目录法利用构效关系（SAR），我们在ICOS/ICOSL TR-FRET测定中鉴定出一种IC50值为4.68±(0.47) μM的抑制剂。值得注意的是，该抑制剂在基于共培养表达ICOS的Jurkat T细胞和表达ICOSL的CHO-K1细胞的生物发光细胞测定中显示出剂量依赖性阻断ICOS/ICOSL相互作用的能力。这项工作将为未来旨在开发ICOS/ICOSL相互作用小分子抑制剂作为癌症及其他疾病潜在治疗药物的药物发现努力铺平道路。
