Dihydroxyacetone decreases the dATP pool, inducing replication stress and genomic instability in BEAS-2B cells.

Dihydroxyacetone (DHA), found in sunless tanning products and electronic cigarette aerosol, induces cytotoxic and genotoxic effects in cells. Studies across skin and systemic models demonstrated that DHA induces cell cycle arrest and mitochondrial stress, but its impact on replication is unknown. We investigated DHA exposure effects on lung epithelial BEAS-2B cells to determine if it induces replication stress and genomic instability. Acute DHA exposure generated oxidative stress, triggering 53BP1 foci formation 24 and 48 h after exposure. Evaluation of DNA damage response showed increased levels of pChk2 and pP53, demonstrating activation of double-strand break response. Using a DNA fiber assay, we observed decreased replication fork progression, which coincided with increased micronuclei formation. Removal of DHA from cell media partially alleviated the replication stress, similar to the removal of hydroxyurea, suggesting a reversible effect. Given DHA's incorporation into glycolytic pathways and induction of mitochondrial stress, we examined its effects on nucleotide biosynthesis and pool composition. DHA exposure reduced ribonucleotide reductase (RRM1/2) expression and specifically depleted dATP pools after 48 h. We confirmed that dATP depletion drives replication stress by supplementing cells with adenine during DHA exposure, which decreased DNA lesions, reduced damage signaling, and restored replication. Adenine supplementation also partially rescued DHA-induced cytotoxicity and micronuclei formation. These data demonstrate that DHA-induced DNA damage and dATP pool depletion cause replication stress in BEAS-2B cells, providing new information on DHA's genotoxic mechanism. The inability of adenine to completely rescue micronuclei formation also suggests additional mechanisms of action that impact mitosis, requiring further investigation.