Discovery of Benzodiazepine-Based Inhibitors of the E2 Enzyme UBCH10 from a Cell-Based p21 Degradation Screen
Benoit Pelletier1, Stéphanie Duhamel1, Guillaume Tambutet1
1Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada.
Abstract:
p21Cip1 (p21) is a universal cyclin-dependent kinase (CDK) inhibitor that halts cell proliferation and tumor growth by multiple mechanisms. The expression of p21 is often downregulated in cancer cells as a result of the loss of function of transcriptional activators, such as p53, or the increased degradation rate of the protein. To identify small molecules that block the ubiquitin-mediated degradation of p21 as a future avenue for cancer drug discovery, we have screened a compound library using a cell-based reporter assay of p21 degradation. This led to the identification of a benzodiazepine series of molecules that induce the accumulation of p21 in cells. Using a chemical proteomic strategy, we identified the ubiquitin-conjugating enzyme UBCH10 as a cellular target of this benzodiazepine series. We show that an optimized benzodiazepine analogue inhibits UBCH10 ubiquitin-conjugating activity and substrate proteolysis by the anaphase-promoting complex.
Insights
Researchers identified novel benzodiazepine molecules that stabilize the p21 protein by inhibiting the UBCH10 enzyme. This discovery offers a new strategy for cancer drug development by preventing tumor cell proliferation.
Area of Science:
- Oncology
- Molecular Biology
- Drug Discovery
Background:
- p21Cip1 (p21) is a crucial cyclin-dependent kinase (CDK) inhibitor that suppresses cell proliferation and tumor growth.
- Cancer cells often exhibit reduced p21 expression due to factors like p53 dysfunction or accelerated protein degradation.
Purpose of the Study:
- To discover small molecules that inhibit the ubiquitin-mediated degradation of p21.
- To explore novel cancer therapeutic strategies by targeting p21 stability.
Main Methods:
- Screening of a compound library using a cell-based reporter assay for p21 degradation.
- Chemical proteomic analysis to identify the molecular targets of identified compounds.
- Biochemical assays to assess the inhibitory activity of drug candidates on target enzymes.
Main Results:
- Identification of a benzodiazepine series of compounds that increase intracellular p21 levels.
- Pinpointing ubiquitin-conjugating enzyme UBCH10 as the cellular target of these benzodiazepines.
- Demonstration that an optimized benzodiazepine analogue inhibits UBCH10 activity and subsequent proteolysis.
Conclusions:
- Benzodiazepine derivatives targeting UBCH10 can stabilize p21 protein.
- Inhibition of UBCH10 represents a promising approach for cancer therapy by restoring p21 function.
- This study provides a foundation for developing new drugs to combat cancer by modulating protein degradation pathways.
