Chromium(VI)-mediated DNA damage: oxidative pathways resulting in the formation of DNA breaks and abasic sites

• Type: Article in International Scientific Journal
• Date: 1999

Authors

Casadevall, M (Author) Other; Fresco, PD (Author) FFUP; Kortenkamp, A (Author) Other

Journal

Title: Chemico-Biological Interactions

Vol. 123

Pages: 117-132

ISSN: 0009-2797

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 47 Citations

Scopus - 57 Citations

Scientific classification

FOS: Medical and Health sciences > Basic medicine

Other information

Authenticus ID: P-001-2SX

DOI: 10.1016/s0009-2797(99)00128-3

Abstract (EN): Inside cells chromium(VI) is activated to its ultimate carcinogenic form by reducing agents including glutathione (GSH) and ascorbate (AsA). The precise mechanism by which DNA damaging species are formed is unclear. In earlier in vitro work with isolated DNA we have shown that chromium(VI) in combination with GSH or AsA is able to induce similar numbers of single strand breaks and apurinic/apyrimidinic sites (AP-sites). Moreover, the formation of both lesions followed a similar temporal pattern. Tt is conceivable that the two forms of DNA damage arise from a common precursor lesion (e.g. hydrogen abstraction at C4' of the DNA sugar moiety) with a partitioning along two pathways, one yielding an AP-site, the other a single strand break (SSB) and a base propenal. The present study is intended to test this hypothesis by analysing whether oxidation products of deoxyribose can be formed in the presence of chromium(Vl) and GSH or AsA. It was found that mixtures of chromium(VI) and GSH or AsA were able to oxidise: 2-deoxyribose to yield malondialdehyde, which was detected by reaction with thiobarbituric acid. The characteristic pink chromogen, which forms upon reaction with thiobarbituric acid, was also observed with calf thymus DNA as the substrate. In both experimental systems the addition of catalase prevented the formation of deoxyribose breakdown products. Hydroxyl radicals did not seem to be important for the generation of DNA damage as the characteristic modified DNA bases could not be detected by using gas chromatography-mass spectrometry. These results lead us to conclude that the formation of SSB during the reductive conversion of chromium(VI) proceeds primarily via hydrogen abstraction from C4'. The observation that Fenton chemistry is not involved in these processes is intriguing and necessitates further research into the ways in which chromium can activate molecular oxygen to form DNA damaging species.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 16