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Updated: Jul 9, 2025
Yeast As a Chassis for Developing Functional Assays to Study Human P53
Published on: August 4, 2019
Clinical and functional analysis of the germline TP53 p.K164E acetylation site variant
Emilia Modolo Pinto1, Enilze M S F Ribeiro2, Jinling Wang3
1Department of Pathology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA; emilia.pinto@stjude.org enilzeribeiro@gmail.com gerard.zambetti@stjude.org.
Abstract:
TP53 plays a critical role as a tumor suppressor by controlling cell cycle progression, DNA repair, and apoptosis. Post-translational modifications such as acetylation of specific lysine residues in the DNA binding and carboxy-terminus regulatory domains modulate its tumor suppressor activities. In this study, we addressed the functional consequences of the germline TP53 p.K164E (NM_000546.5: c.490A>G) variant identified in a patient with early-onset breast cancer and a significant family history of cancer. K164 is a conserved residue located in the L2 loop of the p53 DNA binding domain that is post-translationally modified by acetylation. In silico, in vitro, and in vivo analyses demonstrated that the glutamate substitution at K164 marginally destabilizes the p53 protein structure but significantly impairs sequence-specific DNA binding, transactivation, and tumor cell growth inhibition. Although p.K164E is currently considered a variant of unknown significance by different clinical genetic testing laboratories, the clinical and laboratory-based findings presented here provide strong evidence to reclassify TP53 p.K164E as a likely pathogenic variant.
Insights
The TP53 p.K164E variant, found in early-onset breast cancer, impairs tumor suppressor functions. This study reclassifies it as likely pathogenic, impacting cancer risk assessment.
Area of Science:
- Genetics
- Molecular Biology
- Cancer Research
Background:
- The TP53 gene is a critical tumor suppressor involved in cell cycle control, DNA repair, and apoptosis.
- Post-translational modifications, like acetylation, regulate TP53's tumor suppressor activity.
- Germline variants in TP53 are associated with hereditary cancer syndromes.
Purpose of the Study:
- To investigate the functional impact of the germline TP53 p.K164E variant.
- To determine the clinical significance of the TP53 p.K164E variant in early-onset breast cancer.
Main Methods:
- In silico, in vitro, and in vivo analyses were employed.
- Structural and functional assays were performed on the p53 protein with the K164E substitution.
- DNA binding, transactivation, and tumor cell growth inhibition were assessed.
Main Results:
- The p.K164E substitution marginally destabilizes the p53 protein structure.
- Sequence-specific DNA binding and transactivation functions of p53 are significantly impaired.
- Tumor cell growth inhibition by p53 is significantly reduced.
Conclusions:
- The TP53 p.K164E variant demonstrates impaired tumor suppressor functions.
- Evidence supports reclassifying TP53 p.K164E from a variant of unknown significance to likely pathogenic.
- This finding has implications for genetic testing and cancer risk assessment.
