Design, synthesis, biological evaluation and structure-activity relationship study of quinazolin-4(3H)-one derivatives as novel USP7 inhibitors.

Recent research has indicated that the abnormal expression of the deubiquitinase USP7 induces tumorigenesis via multiple cell pathways, and in particular, the p53-MDM2-USP7 pathway is well understood. USP7 is emerging as a promising target for cancer therapy. However, there are limited reports on USP7 inhibitors. Here we report design, synthesis and biological evaluation of novel quinazolin-4(3 H)-one derivatives as potent USP7 inhibitors. Our results indicated that the compounds C9 and C19 exhibited the greatest potency against the USP7 catalytic domain, with IC 50 values of 4.86 μM and 1.537 μM, respectively. Ub-AMC assays further confirmed IC 50 values of 5.048 μM for C9 and 0.595 μM for C19. MTT assays indicated that gastric cancer MGC-803 cells were more sensitive to these compounds than BGC-823 cells. Flow cytometry analysis revealed that C9 restricted cancer cell growth at the G0/G1 and S phases and inhibited the proliferation and clone formation of MGC-803 cells. Further biochemical experiments indicated that C9 decreased the MDM2 protein level and increased the levels of the tumour suppressors p53 and p21 in a dose-dependent manner. Docking studies predicted that solvent exposure of the side chains of C9 and C19 would uniquely form hydrogen bonds with Met407 of USP7. Additionally, C9 exhibited a remarkable anticancer effect in a zebrafish gastric cancer MGC-803 cell model. Our results demonstrated that quinazolin-4(3 H)-one derivatives were suitable as leads for the development of novel USP7 inhibitors and especially for anti-gastric cancer drugs. [Display omitted] • A series of novel quinazolin-4(3 H)-one derivatives were synthesized. • C9 and C19 were the most potent USP7 inhibitors with IC 50 = 4.86 μM and 1.537 μM. • The derivatives exhibited moderate inhibitory activity against gastric cancer cells. • Biochemical experiments confirmed the effect of C9 on the p53-MDM2-USP7 pathway. • Docking studies predicted important hydrogen bonds between C9 and Met407 of USP7. [ABSTRACT FROM AUTHOR]