Cancer genome sequencing has identified numerous somatic mutations whose
biologic relevance is uncertain. In this study, we used genome-editing tools to create and analyze targeted somatic mutations in murine models of
liver cancer.
Transcription activator-like effector nucleases (
TALEN) were designed against β-
catenin (Ctnnb1) and
adenomatous polyposis coli (Apc), two commonly mutated genes in
hepatocellular carcinoma (HCC), to generate isogenic HCC cell lines. Both mutant cell lines exhibited evidence of Wnt pathway dysregulation. We asked whether these
TALENs could create targeted somatic mutations after hydrodynamic transfection into mouse liver.
TALENs targeting β-
catenin promoted endogenous HCC carrying the intended gain-of-function mutations. However,
TALENs targeting Apc were not as efficient in inducing in vivo homozygous loss-of-function mutations. We hypothesized that hepatocyte
polyploidy might be protective against
TALEN-induced loss of heterozygosity, and indeed Apc gene editing was less efficient in
tetraploid than in diploid hepatocytes. To increase efficiency, we administered adenoviral Apc
TALENs and found that we could achieve a higher mutagenesis rate in vivo. Our results demonstrate that genome-editing tools can enable the in vivo study of cancer genes and faithfully recapitulate the mosaic nature of mutagenesis in mouse
cancer models.
Cancer Res; 74(18); 5311-21. ©2014 AACR.