ADH5 forms a novel pathway that sustains cellular redox balance in cancer cells

CARLA UMANSKY; MARCO SCHEIDEGGER; AGUSTÍN MORELLATO; LUCAS B. PONTEL

Congreso; Reunión Anual de Sociedades de Biosciencias SAIC SAF SAFIS; 2019

SAIC

Cellular metabolism provides energy and molecules required for growth and development. Some biological reactions such as histone demethylations or the one carbon cycle can also generate genotoxic metabolites such as formaldehyde (FA). Cancer cells are metabolically very active and might require robust systems to counteract FA. We therefore set out to address (I) how do cancer cells cope with FA? and (II) how does FA cause cytotoxicity?In mice, FA is counteracted by the enzyme Alcohol dehydrogenase 5 (ADH5). To investigate whether ADH5 prevents FA toxicity in cancer cells we used CRISPR/Cas9 to inactivate ADH5 in human colorectalcarcinoma (HCT116) and lymphoblastic leukaemia (Nalm6) cells. We found that ∆ADH5 cells are sensitive to FA in a resazurin-based viability assay (LD50 Wild type= 150.3±0.21µM; ∆ADH5 =89.95±0.17µM). In contrast to wild type cells, HCT116 ∆ADH5 cells are not able to form spheres above 50 µM FA. By western blot, we found that 150 µM FA induces the phosphorylation of the tumour suppressor P53. However, the DNA damage marker γ-H2Ax is not significantly induced by FA compared to 4 µM cisplatin, a genotoxic drug. Concordantly with a non-significant increase in chromosome aberrations quantified by metaphase scoring. In contrast, oxidative stress was significantly detected by using a fluorescein-based probe and the sensor roGFP. To understand whether FA-induced oxidative stress leads to cell death, we combined FA and the antioxidants N-acetylcysteine and mono-ethyl-GSH. Both antioxidants suppressed FA toxicity (p