DNA damage induced by hypochlorite and hypobromite with reference to inflammation-associated carcinogenesis

Hypohalites (OCl−, OBr−) are formed at inflammation sites as antimicrobial agents. OCl− is also used for the disinfection of water supplies and the association of drinking chlorinated water with cancer risk is pointed out. In this study, OCl− itself induced 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) formation, while OBr− damaged DNA only when glutathione (GSH) was added. OCl− caused oxidative DNA damage more efficiently than OBr−/GSH. In experiment with 32P-labeled DNA fragments, OCl− strongly caused piperidine-labile sites at guanine residues than piperidine-inert 8-oxodG, whereas OBr−/GSH caused no piperidine-labile sites. Endogenous OCl− may play a role in genotoxicity close to the site of inflammation.