Identification of new leads against ubiquitin specific protease-7 (USP7): a step towards the potential treatment of cancers†

Ubiquitin-specific protease-7 (USP7) is an important drug target as it regulates multiple proteins and genes (such as MDM2 and p53) with roles in cancer progression. Its inhibition can hinder the function of oncogenes, increase tumor suppression, and enhance immune response. The current study was designed to express USP7 in a prokaryotic system, followed by screening of small molecules against it using biophysical methods, primarily STD-NMR technique. Among them, 12 compounds showed interaction with USP7 as inferred from NMR-based screening. These compounds further caused destabilization of USP7 by reducing its melting temperature (T_m) up to 6 °C in thermal shift assay. Molecular docking and simulation studies revealed that these compounds bind to the putative substrate binding pocket of USP7 and thus may block the entry of the substrate. Four compounds i.e., 4-hydroxy-diphenyl amine (2), phenyl-(2,3,4-trihydroxyphenyl) methanone (3), 4′-amino-2′,5′-diethoxy benzanilide (5), and hydroquinone (12), showed anti-cancer activity against colorectal cancerous cells (HCT116) with IC₅₀ values in the range of 31–143 μM. These compounds also down-regulated the mRNA expression of the MDM2 gene and up-regulated the mRNA expression of the p53 gene in HCT116 cells, as studied using qPCR analysis. This study thereby identifies several negative modulators of USP7 that can be studied further as potential anti-cancer agents.