p53 partial loss-of-function mutations sensitize to chemotherapy

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• The tumor suppressor p53 is frequently inactivated in cancers via missense mutations, primarily in its DNA binding domain.
• Hotspot mutations (30%) cause complete loss-of-function, leading to chemotherapy resistance.
• Non-hotspot mutations (70%) often result in partial loss-of-function (partial-LOF) with residual activity, whose therapeutic impact is unclear.

Purpose of the Study:

• To investigate the therapeutic consequences of partial-LOF p53 mutations.
• To determine if partial-LOF p53 enhances oncogenesis and influences chemotherapy response.

Main Methods:

• Engineered a p53 mutation to reduce DNA binding, creating a partial-LOF model.
• Utilized mouse models of lung adenocarcinoma, pancreatic ductal adenocarcinoma, and acute myeloid leukemia.
• Analyzed mutant p53 protein accumulation and transcriptional activity in tumors.
• Assessed chemotherapy response and survival benefit in treated mice.

Main Results:

• Engineered partial-LOF p53 enhanced oncogene-driven tumorigenesis in multiple cancer models.
• Partial-LOF mutations led to significant mutant p53 protein accumulation, similar to hotspot mutants.
• Contrary to complete loss-of-function, partial-LOF mutations sensitized tumors to apoptotic chemotherapy, conferring a survival advantage.
• Pro-apoptotic activity of partial-LOF mutants was restored at high protein levels.

Conclusions:

• Partial-LOF p53 mutations contribute to tumorigenesis and have distinct therapeutic implications.
• The accumulation of partial-LOF p53 mutants drives an apoptotic response to chemotherapy.
• Distinguishing partial-LOF p53 mutations is crucial for understanding their role in cancer and potential therapeutic strategies.