TALEN-mediated somatic mutagenesis in murine models of cancer

Area of Science:

• Cancer Genomics
• Molecular Biology
• Hepatocellular Carcinoma Research

Background:

• Cancer genome sequencing reveals numerous somatic mutations with unknown biological significance.
• Hepatocellular carcinoma (HCC) frequently harbors mutations in genes such as β-catenin (Ctnnb1) and adenomatous polyposis coli (Apc).
• Understanding the functional impact of these mutations in vivo is crucial for cancer research.

Purpose of the Study:

• To utilize genome-editing tools, specifically Transcription Activator-Like Effector Nucleases (TALENs), for creating and analyzing targeted somatic mutations in mouse models of liver cancer.
• To investigate the efficiency of TALENs in generating mutations in commonly altered cancer genes (Ctnnb1 and Apc) in vivo.
• To explore the potential influence of hepatocyte ploidy on gene-editing efficiency for loss-of-function mutations.

Main Methods:

• Designed TALENs targeting the β-catenin (Ctnnb1) and adenomatous polyposis coli (Apc) genes.
• Generated isogenic HCC cell lines carrying targeted mutations.
• Administered TALENs via hydrodynamic transfection into mouse liver to induce somatic mutations in vivo.
• Utilized adenoviral delivery of Apc TALENs to enhance mutagenesis efficiency.

Main Results:

• TALENs targeting Ctnnb1 successfully promoted endogenous HCC with the intended gain-of-function mutations.
• TALENs targeting Apc showed lower efficiency in inducing homozygous loss-of-function mutations in vivo.
• Apc gene editing was less efficient in tetraploid hepatocytes compared to diploid hepatocytes, supporting the hypothesis of polyploidy protection.
• Adenoviral delivery of Apc TALENs significantly increased the in vivo mutagenesis rate.

Conclusions:

• Genome-editing tools, such as TALENs, are effective for in vivo studies of cancer genes.
• This approach enables the faithful recapitulation of mutagenesis in mouse cancer models, mirroring the mosaic nature of cancer development.
• The findings provide a powerful platform for investigating the biological relevance of somatic mutations in cancer.