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Updated: Jul 13, 2026
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Yeast As a Chassis for Developing Functional Assays to Study Human P53
Published on: August 4, 2019
HDM2 antagonist Nutlin-3 disrupts p73-HDM2 binding and enhances p73 function
L M S Lau1, J K Nugent, X Zhao
1Division of Hematology/Oncology, Department of Paediatrics, Hospital for Sick Children, University of Toronto, Ontario, Canada.
Oncogene
|August 19, 2007
Summary
Nutlin-3 triggers cell death independently of p53 by targeting p73. This small molecule inhibitor disrupts the p73-HDM2 interaction, enhancing p73
Area of Science:
- Molecular Biology
- Cancer Research
- Cell Death Mechanisms
Background:
- Nutlin-3 is a small molecule inhibitor known to activate p53 by disrupting its association with HDM2.
- p53-null cancer cells exhibit Nutlin-3-induced cell death, suggesting a p53-independent mechanism.
- p73, a homolog of p53, also induces apoptosis and is negatively regulated by HDM2.
Purpose of the Study:
- To investigate whether p73 mediates Nutlin-3-induced apoptosis in p53-null cells.
- To elucidate the mechanism of Nutlin-3 action in the context of p53 inactivation.
Main Methods:
- Assessed the interaction between p73 and HDM2 in p53-null cells treated with Nutlin-3.
- Measured the transcriptional activity of p73 and the expression of its target genes (noxa, puma, p21).
- Utilized siRNA to knock down p73 and evaluated the effect on Nutlin-3-induced apoptosis.
- Determined the impact of Nutlin-3 on TAp73alpha protein levels and half-life.
Main Results:
- Nutlin-3 inhibited the binding of the proapoptotic p73 isoform TAp73alpha to HDM2 in p53-null cells.
- This dissociation led to increased p73 transcriptional activity, upregulating target genes noxa, puma, and p21.
- Nutlin-3 treatment enhanced apoptosis, which was partially rescued by p73 knockdown.
- Nutlin-3 increased TAp73alpha protein levels and prolonged its half-life.
Conclusions:
- Nutlin-3 disrupts the endogenous p73-HDM2 interaction, enhancing p73 stability and proapoptotic activity.
- This p73-dependent mechanism provides a rationale for using Nutlin-3 in human tumors with p53 inactivation.
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