Sex and Alkyladenine DNA Glycosylase Expression are Key Susceptibility Factors for NDMA-induced Mutations, Toxicity, and Cancer

N-Nitrosodimethylamine (NDMA) is present in food, water, and drugs and is considered a probable human carcinogen by the International Agency for Research on Cancer. The mechanism of action of NDMA involves the generation of carcinogenic methyl lesions such as 3-methyladenine (3MeA) on DNA bases. Alkyladenine DNA Glycosylase (AAG) removes 3MeA to initiate Base Excision Repair, leaving an intermediary lesion that is subsequently resolved by backbone cleavage, nucleotide insertion, and backbone ligation. The intermediate steps following lesion removal produce potentially toxic and mutagenic single-strand DNA breaks. Here, we explored differences between males and females regarding downstream DNA damage, toxicity, mutations and cancer arising from 3MeA in the livers of WT,Aag^-/-, andAag-overexpressing (AagTg) mice. We found that males were more susceptible to NDMA-induced mutations (WT andAag^-/-) and cancer (all genotypes). In contrast,AagTgfemales were more prone than males to micronucleus induction. As we showed in our prior analyses where data were pooled for males and females,Aag^-/-mice were significantly more susceptible to NDMA-induced mutations and cancer, andAagTgmice displayed significantly greater toxicity. Building on these findings, our analyses of sex-related differences show thatAagdeficiency and maleness are both susceptibility factors for NDMA-induced liver cancer, whileAagoverexpression drives toxicity, potentially with a greater effect on females. By assessing differences between males and females, this study reveals a deeper mechanistic understanding of the underpinnings for a well-known increased risk of liver cancer in men versus women by demonstrating a higher susceptibility of male mice to both mutations and cancer.