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p53: Multiple Facets of a Rubik's Cube
Yun Zhang1, Guillermina Lozano1
1Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030.
Abstract:
The p53 tumor suppressor has been studied for decades, and still there are many questions left unanswered. In this review, we first describe the current understanding of the wild-type p53 functions that determine cell survival or death, and regulation of the protein, with a particular focus on the negative regulators, the murine double minute family of proteins. We also summarize tissue-, stress-, and age-specific p53 activities and the potential underlying mechanisms. Among all p53 gene alterations identified in human cancers, p53 missense mutations predominate, suggesting an inherent biological advantage. Numerous gain-of-function activities of mutant p53 in different model systems and contexts have been identified. The emerging theme is that mutant p53, which retains a potent transcriptional activation domain, also retains the ability to modify gene transcription, albeit indirectly. Lastly, because mutant p53 stability is necessary for its gain of function, we summarize the mechanisms through which mutant p53 is specifically stabilized. A deeper understanding of the multiple pathways that impinge upon wild-type and mutant p53 activities and how these, in turn, regulate cell behavior will help identify vulnerabilities and therapeutic opportunities.
Insights
This review explores the p53 tumor suppressor, detailing wild-type functions, regulation by murine double minute proteins, and tissue-specific activities. It highlights mutant p53 gain-of-function activities and stabilization mechanisms in cancer.
Area of Science:
- Molecular Biology
- Cancer Biology
- Genetics
Background:
- The p53 tumor suppressor is a critical regulator of cell fate, involved in cell survival and death pathways.
- Decades of research have elucidated many p53 functions, yet significant questions remain regarding its complex roles.
- Negative regulators, such as the murine double minute (MDM) protein family, play crucial roles in p53 regulation.
Purpose of the Study:
- To review the current understanding of wild-type p53 functions and regulation.
- To summarize tissue-, stress-, and age-specific p53 activities and their underlying mechanisms.
- To explore the gain-of-function activities and stabilization mechanisms of mutant p53 in human cancers.
Main Methods:
- Literature review of existing research on p53.
- Analysis of p53 gene alterations in human cancers, focusing on missense mutations.
- Examination of experimental model systems and contexts to identify mutant p53 activities.
Main Results:
- Wild-type p53 functions in cell survival/death and regulation are detailed, with emphasis on MDM proteins.
- p53 activities show variations across different tissues, stress conditions, and ages.
- p53 missense mutations are predominant in cancers, exhibiting gain-of-function activities by modifying gene transcription indirectly.
- Mechanisms stabilizing mutant p53 are summarized, crucial for its oncogenic functions.
Conclusions:
- Understanding wild-type and mutant p53 pathways is key to identifying cancer vulnerabilities.
- Mutant p53's ability to retain transcriptional modification capabilities, despite alterations, is a significant finding.
- Targeting the stabilization pathways of mutant p53 may offer therapeutic opportunities in cancer treatment.