Characterizing multi-PIK3CA mutations across cancer types: Toward precision oncology

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) mutations are prevalent in numerous cancers.
• The functional impact of multiple PIK3CA mutations and their spatial orientations within the gene remains underexplored.

Purpose of the Study:

• To investigate the prevalence and orientation patterns of multi-PIK3CA mutations across a broad spectrum of cancers.
• To determine if mutation orientation correlates with oncogenic potential and therapeutic implications.

Main Methods:

• Analysis of multi-PIK3CA mutations in a pan-cancer cohort of 3564 tumors.
• Categorization of mutations based on their location within PIK3CA domains (helical, kinase ABD, C2) and orientation (cis/trans).

Main Results:

• Multi-PIK3CA mutations were identified in 10.3% of PIK3CA-mutant tumors, primarily in breast and gynecological cancers.
• Helical domain mutations (E542:E545) exclusively presented in the trans-orientation.
• Mutations in the kinase ABD and C2 domains predominantly occurred in the cis orientation.

Conclusions:

• Distinct PIK3CA mutation orientation patterns suggest varied oncogenic activities.
• Trans-oriented helical domain mutations may possess reduced oncogenic potential.
• Mutation orientation serves as a potential biomarker for guiding PI3K inhibitor-based targeted cancer therapies and clinical trial design.