Repurposing of US-FDA-approved drugs as negative modulators of ubiquitin specific protease-7 (USP7)

Area of Science:

• Biochemistry
• Pharmacology
• Oncology

Background:

• Ubiquitin-specific protease 7 (USP7) is crucial for cancer cell survival by regulating tumor suppressor proteins like p53.
• USP7's aberrant expression drives human malignancies, making it a validated anti-cancer drug target.
• Drug repurposing offers a cost- and time-effective strategy for identifying novel therapeutic agents.

Purpose of the Study:

• To identify novel USP7 inhibitors using a drug repurposing approach.
• To characterize the binding affinity and mechanism of identified compounds.
• To evaluate the anti-cancer activity of lead compounds in relevant cellular models.

Main Methods:

• Nuclear Magnetic Resonance (NMR)-based screening of 172 approved drugs against USP7.
• Determination of dissociation constants (Kd) and thermal stability changes (melting temperature).
• Molecular docking and simulation studies to elucidate binding modes.
• Assessment of anti-cancer activity and effects on proto-oncogene and tumor-suppressor gene expression in HCT116 cells.

Main Results:

• NMR screening identified 11 compounds binding to USP7's catalytic domain with Kd values between 0.6-1.49 mM.
• These compounds thermally destabilized USP7, reducing its melting temperature by up to 9°C.
• Docking studies indicated binding within the substrate-binding pocket, interacting with key catalytic residues.
• Oxybutynin, ketotifen, pantoprazole sodium, and escitalopram demonstrated anti-cancer effects and modulated gene expression at the mRNA level in HCT116 cells.

Conclusions:

• Drug repurposing successfully identified novel small molecules targeting USP7.
• The identified compounds, particularly oxybutynin, ketotifen, pantoprazole sodium, and escitalopram, show potential as anti-cancer leads.
• These compounds warrant further investigation for developing new USP7-targeted cancer therapies.