AbstractThe cysteine protease cathepsin S (CatS) is overexpressed in many tumors. It is known to be involved in tumor progression as well as antigen processing in antigen‐presenting cells (APC). Recent evidence suggests that silencing CatS improves the anti‐tumor immune response in several cancers. Therefore, CatS is an interesting target to modulate the immune response in these diseases. Here, we present a series of covalent‐reversible CatS inhibitors based on the α‐fluorovinylsulfone and ‐sulfonate warheads. We optimized two lead structures by molecular docking approaches, resulting in 22 final compounds which were evaluated in fluorometric enzyme assays for CatS inhibition and for selectivity towards the off‐targets CatB and CatL. The most potent inhibitor in the series has subnanomolar affinity (Ki=0.08 nM) and more than 100,000‐fold selectivity towards cathepsins B and L. These new reversible and non‐cytotoxic inhibitors could serve as interesting leads to develop new immunomodulators in cancer therapy.
摘要半胱氨酸蛋白酶 cathepsin S(CatS)在许多肿瘤中过度表达。众所周知,它参与了肿瘤的进展以及抗原递呈细胞(APC)的抗原处理。最近的证据表明,沉默 CatS 可以改善几种癌症的抗肿瘤免疫反应。因此,CatS 是调节这些疾病免疫反应的一个有趣靶点。在此,我们介绍了一系列基于α-氟乙烯砜和-磺酸盐弹头的共价可逆 CatS 抑制剂。我们通过分子对接方法优化了两种先导结构,最终得到了 22 种化合物,并在荧光酶测定法中评估了它们对 CatS 的抑制作用以及对非靶标 CatB 和 CatL 的选择性。该系列中最有效的抑制剂具有亚摩尔亲和力(Ki=0.08 nM),对Cathepsins B和L的选择性超过100,000倍。