FY25 Defining TP53 Mutations in the Li-Fraumeni Spectrum - Elucidating Specific Effects of TP53 Mutations

Abstract: Since beginning an inherited cancer program in the DanceBlue Pediatric Hematology/Oncology clinic at Kentucky Children’s Hospital (KCH), we have identified patients with four distinct germline heterozygous TP53 mutations who presented with cancer as children or young adults. We are interested in comparing the impact of the distinct TP53 mutations on the expression, stability, and function of the p53 tumor suppressor in order to gain an understanding of how each mutation may have contributed to oncogenesis as well as enrich our knowledge of the genotype-phenotype correlations of TP53 mutations. This proposal represents a bedside-to- bench translational project that derives from the KPCRTF-funded “Project Inherited Cancer Risk” (PICR) program aimed at identifying children, adolescents and young adults with inherited cancer predisposition syndromes. Our goal is to establish, by a combination of biochemical and molecular assays and in-silico approaches, how four distinct TP53 mutations (C141Y, T253I, C176Y, and R213X) each impacts canonical p53 cellular responses such as damage-induced transcriptional regulation, cell cycle checkpoint and apoptosis. We will (1) develop TP53 CRISPR-deleted HEK293 and A549 cell lines with stable complementation of each TP53 mutation as well as wild type (wt; non-mutated) TP53 suitable to study growth and viability, (2) determine how each mutation impacts p53-DNA interactions and transcriptional regulation, and (3) determine how each mutation impacts damage-induced p53 signaling, cell cycle arrest and apoptosis. Our intent is to correlate severity of phenotype with clinical presentation and course, and to publish how each of these clinically-relevant mutations impacts canonical p53 function to add to our collective mechanistic knowledge of how TP53 mutations impact cancer risk. Our work will contribute to the concept that different TP53 mutations lead to a spectrum of dysregulation and clinical severity. Our long-term goal is to develop more specialized patient care based on an informed understanding of how distinct TP53 mutations contribute to oncogenesis. Lay summary of the proposal: We are interested in helping children who have inherited a gene that gives them a higher cancer risk. Our clinic has the privilege of caring for several patients with “Li-Fraumeni Syndrome”, one of the most important genetic cancer syndromes because cancer risk is so high. We want to compare and contrast their specific mutations in the gene responsible for the syndrome (called TP53), in order to understand why some Li-Fraumeni Syndrome patients get many more cancers than others. Our hope is that through understanding the impact that distinct TP53 mutations has on cells, we can better predict which patients will get cancer and allow us to be smarter in our cancer preventive care. This work may also lead to new ways to treat cancers that have specific TP53 mutations.