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Discovery of Mdm2-MdmX E3 ligase inhibitors using a cell-based ubiquitination assay
Ariel G Herman1, Miki Hayano, Masha V Poyurovsky
1Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10027, USA.
Abstract:
E3 ubiquitin ligases are of interest as drug targets for their ability to regulate protein stability and function. The oncogene Mdm2 is an attractive E3 ligase to target, as it is the key negative regulator of the tumor suppressor p53, which controls the transcription of genes involved in cell fate. Overexpression of Mdm2 facilitates tumorigenesis by inactivating p53, and through p53-independent oncogenic effects. We developed a high-throughput cellular Mdm2 auto-ubiquitination assay, which we used to discover a class of small-molecule Mdm2 ligase activity inhibitors. These compounds inhibit Mdm2 and p53 ubiquitination in cells, reduce viability of cells with wild-type p53, and synergize with DNA-damaging agents to cause cell death. We determined that these compounds effectively inhibit the E3 ligase activity of the Mdm2-MdmX hetero-complex. This mechanism may be exploitable to create a new class of anti-tumor agents.
Insights
Researchers discovered small molecules that inhibit Mdm2 ligase activity, a key factor in cancer. These Mdm2 inhibitors reduce cancer cell viability and enhance the effects of chemotherapy, offering a new anti-tumor strategy.
Area of Science:
- Oncology
- Molecular Biology
- Drug Discovery
Background:
- E3 ubiquitin ligases regulate protein stability and function, making them attractive drug targets.
- Mdm2 oncogene inactivates tumor suppressor p53, promoting tumorigenesis through p53-dependent and independent pathways.
Purpose of the Study:
- To develop a high-throughput assay for Mdm2 E3 ligase activity.
- To discover novel small-molecule inhibitors of Mdm2 ligase activity.
- To evaluate the therapeutic potential of these inhibitors in cancer treatment.
Main Methods:
- Development of a high-throughput cellular Mdm2 auto-ubiquitination assay.
- Screening for small-molecule inhibitors of Mdm2 ligase activity.
- In vitro and cellular assays to assess compound efficacy, including ubiquitination, cell viability, and synergy with DNA-damaging agents.
Main Results:
- Discovery of a novel class of small-molecule Mdm2 ligase activity inhibitors.
- Compounds inhibit Mdm2 and p53 ubiquitination in cells.
- Inhibitors reduce the viability of cancer cells with wild-type p53 and synergize with DNA-damaging agents to induce cell death.
- Compounds effectively inhibit the Mdm2-MdmX hetero-complex E3 ligase activity.
Conclusions:
- Small-molecule Mdm2 inhibitors represent a promising new class of anti-tumor agents.
- Targeting Mdm2 ligase activity, particularly within the Mdm2-MdmX hetero-complex, offers a viable therapeutic strategy.
- These findings pave the way for developing novel cancer therapies exploiting Mdm2 inhibition.
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