Defining the genome-wide mutagenic impact of APOBEC3 enzymes.

Somatic mutations drive cancer initiation and tumor evolution. Therefore, the etiology of mutagenesis in cancer is important to preventative and treatment strategies. Somatic mutagenesis in cancer is a multifactorial process and includes both endogenous and exogenous sources of mutations. One recently recognized source of mutagenesis in cancer is the innate immune APOBEC3 family of enzymes, which catalyze cytosine deamination to restrict viral infection but can aberrantly act on the cellular genome, resulting in mutations. Single base substitution (SBS) signatures, or mutational patterns, identified in cancer genomes have demonstrated widespread mutagenesis caused by APOBEC3 enzymes throughout human tumors. To comprehensively define the consequences of APOBEC3 mutagenesis, we developed an experimental pipeline for prospective analysis of genome-wide mutations caused by APOBEC3 activity. This pipeline can be adapted to analyze additional sources of mutagenesis across a spectrum of cells.