Formaldehyde (FA) is an endogenous and environmental metabolite genotoxin that causes DNA and DNA-protein crosslinks. Endogenous FA has been identified as a major genotoxic and carcinogenic agent involved in the onset of the cancer-prone genetic disease Fanconi Anemia and in the development of a type of inherited bone marrow failure syndrome (IBMFS). Here, we employ C. elegans and human carcinoma cells to reveal that FA causes cellular damage by triggering oxidative stress, which is prevented by the alcohol dehydrogenase enzyme ADH5/GSNOR. We identify the ADH5 orthologue in C. elegans (
adh-5; H24K24.3) and show that
adh-5 mutants are hypersensitive to FA. Oxidative stress exacerbates FA sensitivity in ADH-5 deficient worms. Moreover, both worms and cells display ROS accumulation and the activation of oxidative stress responses, which is suppressed by supplementation with the GSH precursor N-acetylcysteine (NAC). Further, we demonstrate that endogenous GSH can protect cells lacking the Fanconi Anemia DNA repair pathway, or worms that are deficient in Nucleotide Excision Repair (NER), from endogenous or environmental FA. Hence, our findings establish a conserved mechanism that protects from FA cytotoxicity, which has broad implications for developing novel intervention strategies for Fanconi Anemia patients and against certain cancers.