Brca2 deficiency drives gastrointestinal tumor formation and is selectively inhibited by mitomycin C

Area of Science:

• Genetics and Genomics
• Cancer Biology
• Oncology

Background:

• BRCA2 is essential for high-fidelity DNA double-strand break repair.
• Loss of BRCA2 function elevates risks for breast and ovarian cancers.
• The role of BRCA2 in gastrointestinal cancers remains less understood.

Purpose of the Study:

• To investigate the mutation status and functional implications of BRCA2 in gastric and colorectal cancers.
• To explore the correlation between BRCA2 inactivation and microsatellite instability.
• To identify potential therapeutic strategies targeting BRCA2-deficient gastrointestinal tumors.

Main Methods:

• Analysis of whole-genome screening data for BRCA2 mutations in gastric and colorectal adenocarcinomas.
• Assessment of the correlation between BRCA2 mutation status and microsatellite instability.
• In vivo studies using mouse models with villin-driven Brca2 depletion.
• Drug sensitivity screening using mitomycin C on BRCA2-mutant tumors.

Main Results:

• BRCA2 is inactively mutated in 10% of gastric and 7% of colorectal adenocarcinomas.
• BRCA2 inactivation significantly correlates with microsatellite instability.
• BRCA2 monoallelic and biallelic mutant tumors are selectively inhibited by mitomycin C.
• Mitomycin C induces double-strand breaks, leading to S-phase arrest and p53-mediated apoptosis in BRCA2-deficient cells.

Conclusions:

• BRCA2 loss plays a role in the pathogenesis of gastrointestinal tumors.
• BRCA2-deficient gastric and colorectal tumors exhibit sensitivity to mitomycin C.
• Mitomycin C represents a potential therapeutic strategy for BRCA2-mutant gastrointestinal adenocarcinomas.