APOBEC3G Rescues Cells from the Deleterious Effects of DNA Damage.

Human apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like 3G (hA3G), a member of the APOBEC family, was described as an anti-HIV-1 restriction factor, deaminating reverse transcripts of the HIV-1 genome. Several types of cancer cells that express high levels of A3G, such as diffuse large B-cell lymphoma cells and glioblastomas, show enhanced cell survival after ionizing radiation (IR) and chemotherapy treatments. Previously, we showed that hA3G promotes (DNA) double-strand breaks repair in cultured cells and it rescues transgenic mice from lethal IR dose. Here we show that A3G rescues cells from the detrimental effects of DNA damage induced by ultraviolet radiation (UV) and by combined bromodeoxyuridine and UV treatments. The combined treatments stimulate the synthesis of cellular proteins, which are exclusively associated with A3G expression. These proteins participate mainly in nucleotide excision repair and homologous recombination DNA repair pathways. Our results implicate A3G inhibition as a potential strategy for increasing tumor cells sensitivity to genotoxic treatments.