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Updated: Aug 2, 2025
Yeast As a Chassis for Developing Functional Assays to Study Human P53
Published on: August 4, 2019
Dimeric p53 Mutant Elicits Unique Tumor-Suppressive Activities through an Altered Metabolic Program
Jovanka Gencel-Augusto1,2, Xiaoping Su3, Yuan Qi3
1The University of Texas MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences, Houston, Texas.
Abstract:
Cancer-related alterations of the p53 tetramerization domain (TD) abrogate wild-type (WT) p53 function. They result in a protein that preferentially forms monomers or dimers, which are also normal p53 states under basal cellular conditions. However, their physiologic relevance is not well understood. We have established in vivo models for monomeric and dimeric p53, which model Li-Fraumeni syndrome patients with germline p53 TD alterations. p53 monomers are inactive forms of the protein. Unexpectedly, p53 dimers conferred some tumor suppression that is not mediated by canonical WT p53 activities. p53 dimers upregulate the PPAR pathway. These activities are associated with lower prevalence of thymic lymphomas and increased CD8+ T-cell differentiation. Lymphomas derived from dimeric p53 mice show cooperating alterations in the PPAR pathway, further implicating a role for these activities in tumor suppression. Our data reveal novel functions for p53 dimers and support the exploration of PPAR agonists as therapies.
Significance:
New mouse models with TP53R342P (monomer) or TP53A347D (dimer) mutations mimic Li-Fraumeni syndrome. Although p53 monomers lack function, p53 dimers conferred noncanonical tumor-suppressive activities. We describe novel activities for p53 dimers facilitated by PPARs and propose these are "basal" p53 activities. See related commentary by Stieg et al., p. 1046. See related article by Choe et al., p. 1250. This article is highlighted in the In This Issue feature, p. 1027.
Insights
Cancer mutations in p53 tetramerization domain (TD) create inactive monomers or tumor-suppressive dimers. These p53 dimers activate the PPAR pathway, offering novel therapeutic strategies for Li-Fraumeni syndrome.
Area of Science:
- Molecular Biology
- Cancer Research
- Immunology
Background:
- Alterations in the p53 tetramerization domain (TD) disrupt wild-type (WT) p53 function, leading to monomeric or dimeric forms.
- The physiological roles of these p53 monomers and dimers, particularly in cancer, remain incompletely understood.
- Li-Fraumeni syndrome patients with germline p53 TD alterations provided the basis for developing in vivo models.
Discussion:
- p53 monomers were found to be inactive, while p53 dimers exhibited unexpected tumor-suppressive capabilities independent of canonical WT p53 activities.
- p53 dimer activity was linked to the upregulation of the PPAR pathway, suggesting a novel mechanism of tumor suppression.
- Observed outcomes included a reduced incidence of thymic lymphomas and enhanced CD8+ T-cell differentiation in mouse models.
Key Insights:
- Novel mouse models with specific TP53 mutations (TP53R342P for monomer, TP53A347D for dimer) were created to mimic Li-Fraumeni syndrome.
- p53 dimers demonstrated noncanonical tumor-suppressive functions, distinct from the known activities of WT p53.
- These dimeric p53 activities, facilitated by PPARs, are proposed as potentially "basal" p53 functions.
Outlook:
- The findings highlight previously unrecognized functions of p53 dimers in tumor suppression.
- The study suggests that PPAR agonists could be explored as a potential therapeutic avenue for cancers associated with p53 TD alterations.
- Further research into the interplay between p53 dimers and the PPAR pathway may uncover new strategies for cancer treatment.
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