Ubiquitin specific peptidase 28 (USP28) is closely associated to the occurrence and development of various malignancies, and thus has been validated as a promising therapeutic target for cancer therapy. To date, only few USP28 inhibitors with moderate inhibitory activity have been reported, highly potent and selective USP28 inhibitors with new chemotypes remain to be discovered for pathologically investigating the roles of deubiquitinase. In this current study, we reported the synthesis and biological evaluation of new [1,2,3]triazolo[4,5-d]pyrimidine derivatives as potent USP28 inhibitors. Especially, compound 19 potently inhibited USP28 (IC₅₀ = 1.10 ± 0.02 μmol/L, K_d = 40 nmol/L), showing selectivity over USP7 and LSD1 (IC₅₀ > 100 μmol/L). Compound 19 was cellularly engaged to USP28 in gastric cancer cells. Compound 19 reversibly bound to USP28 and directly affected its protein levels, thus inhibiting the proliferation, cell cycle at S phase, and epithelial-mesenchymal transition (EMT) progression in gastric cancer cell lines. Docking studies were performed to rationalize the potency of compound 19. Collectively, compound 19 could serve as a new tool compound for the development of new USP28 inhibitors for exploring the roles of deubiquitinase in cancers.

泛素特异性肽酶28（USP28）与各种恶性肿瘤的发生和发展密切相关，因此已被证实是有希望的癌症治疗靶标。迄今为止，只有少数具有中等抑制活性的USP28抑制剂被报道，具有新化学型的高效和选择性USP28抑制剂仍有待病理学研究去泛素酶的作用。在当前的这项研究中，我们报道了新的[1,2,3]三唑[4,5- d ]嘧啶衍生物作为强效USP28抑制剂的合成和生物学评估。特别是化合物19可以有效抑制USP28（IC ₅₀  = 1.10±0.02μmol/ L，K _d = 40 nmol / L），显示出对USP7和LSD1的选择性（IC ₅₀  > 100μmol/ L）。化合物19在胃癌细胞中与USP28细胞结合。化合物19可逆地与USP28结合并直接影响其蛋白水平，从而抑制了胃癌细胞系的增殖，S期细胞周期以及上皮-间质转化（EMT）进展。对接研究进行了合理化的化合物19的效力。总的来说，化合物19可以用作开发新USP28抑制剂的新工具化合物，以探索去泛素酶在癌症中的作用。