Open AccessAPOBEC3A is a prominent cytidine deaminase in breast cancer
Author(s) -
Luis M. Cortez,
Amber L. Brown,
Madeline A. Dennis,
Christopher D. Collins,
Alexander J. Brown,
Debra Mitchell,
Tony M. Mertz,
Steven A. Roberts
Publication year - 2019
Publication title -
plos genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.587
H-Index - 233
eISSN - 1553-7404
pISSN - 1553-7390
DOI - 10.1371/journal.pgen.1008545
Subject(s) - apobec , cytidine deaminase , cytidine , biology , mutagenesis , rna editing , deamination , activation induced (cytidine) deaminase , genetics , rna , mutation , cancer research , microbiology and biotechnology , somatic hypermutation , gene , enzyme , genome , biochemistry , b cell , antibody
APOBEC cytidine deaminases are the second-most prominent source of mutagenesis in sequenced tumors. Previous studies have proposed that APOBEC3B (A3B) is the major source of mutagenesis in breast cancer (BRCA). We show that APOBEC3A (A3A) is the only APOBEC whose expression correlates with APOBEC-induced mutation load and that A3A expression is responsible for cytidine deamination in multiple BRCA cell lines. Comparative analysis of A3A and A3B expression by qRT-PCR, RSEM-normalized RNA-seq, and unambiguous RNA-seq validated the use of RNA-seq to measure APOBEC expression, which indicates that A3A is the primary correlate with APOBEC-mutation load in primary BRCA tumors. We also demonstrate that A3A has >100-fold more cytidine deamination activity than A3B in the presence of cellular RNA, likely explaining why higher levels of A3B expression contributes less to mutagenesis in BRCA. Our findings identify A3A as a major source of cytidine deaminase activity in breast cancer cells and possibly a prominent contributor to the APOBEC mutation signature.