Identification of novel human USP2 inhibitor and its putative role in treatment of COVID-19 by inhibiting SARS-CoV-2 papain-like (PLpro) protease.

Human ubiquitin carboxyl-terminal hydrolase-2 (USP2) inhibitors, such as thiopurine analogs, have been reported to inhibit SARS-CoV papain-like proteases (PLpro). The PLpro have significant functional implications in the innate immune response during SARS-CoV-2 infection and considered an important antiviral target. Both proteases share strikingly similar USP fold with right-handed thumb-palm-fingers structural scaffold and conserved catalytic triad Cys-His-Asp/Asn. In this urgency situation of COVID-19 outbreak, there is a lack of in-vitro facilities readily available to test SARS-CoV-2 inhibitors in whole-cell assays. Therefore, we adopted an alternate route to identify potential USP2 inhibitor through integrated in-silico efforts. After an extensive virtual screening protocol, the best compounds were selected and tested. The compound Z93 showed significant IC50 value against Jurkat (9.67 µM) and MOTL-4 cells (11.8 µM). The binding mode of Z93 was extensively analyzed through molecular docking, followed by MD simulations, and molecular interactions were compared with SARS-CoV-2. The relative binding poses of Z93 fitted well in the binding site of both proteases and showed consensus π-π stacking and H-bond interactions with histidine and aspartate/asparagine residues of the catalytic triad. These results led us to speculate that compound Z93 might be the first potential chemical lead against SARS-CoV-2 PLpro, which warrants in-vitro evaluations.

Downregulation of ubiquitin-specific protease 2 possesses prognostic and diagnostic value and promotes the clear cell renal cell carcinoma progression.

BACKGROUND: Clear cell renal cell carcinoma (ccRCC), characterized by high mortality, invasion, metastasis, recurrence and drug resistance, is the most common malignant tumor of the urinary system. A clear understanding of the underlying molecular mechanisms and its role during tumorigenesis of RCC can contribute to development of prognostic and targeted therapies. METHODS: We analyzed datasets from the public database, TCGA, Oncomine, for differential expression of ubiquitin-specific protease 2 (USP2), and further investigated its relationship with the clinical stage, pathological grade and prognosis of renal cancer. We used real-time quantitative PCR and western blot analysis to validate USP2 expression in clinical samples and renal cancer cell lines. Finally, we used CCK-8 and transwell assays to determine its effects on biological functions in cells. RESULTS: We observed significantly lower levels of USP2 mRNA in renal cancer, relative to normal, tissues across the four datasets from the Oncomine database (P<0.001), 533 cases from TCGA database (P<0.0001) and 30 pairs of clinical samples (P<0.0001). Similarly, a decreased USP2 protein expression in ccRCC was detected following immunohistochemical (IHC) and western blot analyses. Furthermore, the aberrant expression of USP2 resulted in significant relationship with clinical stage, pathological grade and lower USP2 mRNA expression was interrelated to poor prognosis of renal cell carcinoma. USP2 acted as an independent factor for ccRCC diagnosis, with an AUC of 0.8888 (95% CI: 0.8529 to 0.9246; P<0.0001). Exogenous restoration of USP2 in ccRCC cells resulted in repression of cell proliferation, migration, and invasion. CONCLUSIONS: Overall, these results show that USP2 acts as an anti-oncogene and an independent factor for ccRCC prognosis. Positive modulation of USP2 might lead to development of a novel strategy for ccRCC treatment.