p53 mutants can often transactivate promoters containing a p21 but not Bax or PIG3 responsive elements

Area of Science:

• Molecular Biology
• Cancer Research
• Genetics

Background:

• The p53 protein is a crucial transcription factor regulating cell cycle arrest and apoptosis.
• Mutations in p53 are common in human cancers, often impairing its tumor-suppressive functions.
• Some p53 mutants retain partial activity, potentially influencing cancer development and treatment.

Purpose of the Study:

• To assess the transactivation ability of 77 p53 mutants using a yeast reporter system.
• To identify p53 mutants with retained transcriptional activity, particularly for p21, Bax, and PIG3 genes.
• To explore the clinical implications of functionally distinct p53 mutants.

Main Methods:

• Utilized a yeast reporter strain with a p53-regulated ADE2 gene.
• Assessed transactivation of p21, Bax, and PIG3 promoters by 77 p53 mutants.
• Investigated the influence of temperature on mutant transactivation and analyzed mutations in BRCA-associated tumors.

Main Results:

• A significant proportion of p53 mutants (21%) exhibited transcriptional activity, especially with the p21 promoter.
• Discriminant mutants affected less conserved and rarely mutated amino acids, often showing temperature sensitivity.
• Mutants from BRCA-associated tumors displayed higher transcriptional activity and gain-of-function in transformation assays.

Conclusions:

• The yeast assay provides a valuable tool for functionally characterizing p53 mutants.
• Identifying transcriptionally active p53 mutants, particularly those affecting p21, has potential clinical relevance.
• A functional p53 database derived from yeast assays can bridge biophysical, pharmacological, and clinical research gaps.