Splice-altering TP53 missense mutations as drivers of dysfunction and targets for RNA-based therapy

Area of Science:

• Molecular Biology
• Cancer Genetics
• RNA Biology

Background:

• TP53 missense mutations are common in cancer, but their impact on RNA splicing is not well understood.
• Understanding these post-transcriptional effects is crucial for elucidating p53's loss-of-function mechanisms.

Purpose of the Study:

• To investigate the role of TP53 missense mutations in altering RNA splicing.
• To identify specific TP53 mutations that create new splice sites and affect mRNA integrity.
• To explore therapeutic strategies for correcting splicing defects in TP53-mutant cancers.

Main Methods:

• Analysis of cancer genome databases to identify potential splicing-altering TP53 mutations.
• Minigene assays to experimentally validate the splicing effects of identified mutations.
• Development of TP53 knock-in cell models to assess physiological relevance.
• Application of antisense morpholino oligomers to correct splicing defects.

Main Results:

• Identified 34 TP53 missense and synonymous mutations capable of generating de novo-splice sites.
• Confirmed the splicing-altering potential of several key mutations (e.g., c.178C>A, c.922C>G) through minigene assays.
• Demonstrated that these mutations lead to aberrant splicing, compromised TP53 mRNA integrity, and can trigger nonsense-mediated mRNA decay.
• Successfully restored p53 expression and function using antisense morpholino oligomers.

Conclusions:

• Certain TP53 missense mutations act as splicing-disruptive mutations, contributing to p53 loss-of-function.
• Aberrant splicing and subsequent mRNA decay are significant mechanisms underlying TP53 mutations.
• RNA-based therapeutics targeting splice sites represent a promising strategy for TP53-mutant cancers.