Long-lived Min mice develop advanced intestinal cancers through a genetically conservative pathway

Area of Science:

• Genetics
• Oncology
• Mouse Models

Background:

• Adenomatous polyposis coli (Apc) gene mutations cause intestinal tumors in mice.
• Short lifespan in C57BL/6J Apc(Min/+) mice limits study of tumor progression.
• F(1) Apc(Min/+) hybrids were generated to overcome lifespan limitations.

Purpose of the Study:

• To investigate the development of invasive intestinal cancers in F(1) Apc(Min/+) hybrid mice.
• To determine if genetic instability accelerates tumor progression in the Apc(Min/+) model.
• To identify factors contributing to cancer invasion in the absence of overt genomic instability.

Main Methods:

• Crossed C57BR/cdcJ and SWR/J females with C57BL/6J Apc(Min/+) males to create F(1) hybrids.
• Assessed tumor development, invasion, and metastasis in hybrid mice.
• Induced genetic instability in Apc(Min/+) mice via Nbs1(DeltaB) allele or somatic mutagen treatment.

Main Results:

• F(1) Apc(Min/+) hybrids developed fewer tumors but frequently exhibited invasive adenocarcinomas (24-87%) and occasional metastasis (3%).
• Cancer development did not require chromosomal instability, microsatellite instability, or Helicobacter.
• Imposed genetic instability did not accelerate cancer formation or progression to distant metastasis.

Conclusions:

• The Apc(Min/+) mouse model can develop frequent invasive intestinal cancers without overt genomic instability.
• Factors such as age-dependent epigenetic changes, somatic recombination, or hybrid genetic background may promote invasion.