Oncogenic PIK3CA induces centrosome amplification and tolerance to genome doubling

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Mutations in PIK3CA are common in various cancers, leading to persistent PI3K pathway activation.
• The effects of acute expression of mutant PIK3CA during early malignancy are not well understood.

Purpose of the Study:

• To investigate the impact of activating the Pik3ca H1047R mutation during early cancer development.
• To explore the role of PIK3CA mutations in genomic instability and cancer evolution.

Main Methods:

• Utilized a mouse model to activate the endogenous Pik3ca H1047R mutation in a heterozygous state.
• Analyzed centrosome amplification in cultured cells and mouse tissues.
• Assessed cellular tolerance to spontaneous genome doubling in vitro.
• Examined PIK3CA H1047R mutation timing relative to genome doubling in the TCGA breast cancer cohort.

Main Results:

• Mutant Pik3ca induced centrosome amplification via a pathway involving AKT, ROCK, and CDK2/Cyclin E-nucleophosmin.
• Mutant Pik3ca increased cellular tolerance to spontaneous genome doubling.
• The majority of PIK3CA H1047R mutations in breast cancer precede genome doubling.

Conclusions:

• PIK3CA mutations have previously unappreciated roles in promoting irreversible genomic changes in cancer.
• PI3K signaling contributes to the generation of genomic instability during early malignancy.
• Findings suggest potential therapeutic strategies targeting tumor heterogeneity and evolution, despite limitations for PI3K-targeted therapies.