EVIDENCE THAT LIPID-PEROXIDATION PRODUCTS BIND TO DNA IN LIVER-CELLS

Three lines of evidence are presented indicating the association of lipid peroxidation products with DNA in liver cells, labeled with [H-3]arachidonic acid, in the presence of Fe2+-DTPA: (1) the nuclear DNA isolated from treated cells had higher radioactivity, compared to controls and the radioactivity increased with longer incubation times, (2) lipid-DNA adducts with a characteristic fluorescence spectrum were formed during the incubation with Fe2+-DTPA; (3) the association of peroxidation products with DNA could be inhibited by vitamin E and BHT. Compared with control DNA, purified lipid-DNA adducts showed a decrease of hyperchromicity and melting point, and partial resistance to hydrolysis by DNase I. On the other hand, the repair test shows that the lipid-DNA adducts in cells were not repaired by 4 h after removal of Fe2+-DTPA. A decrease in cell viability and in the activity of O-6-alkylguanine acceptor protein was also observed with increasing incubation time. These data suggest that the lipid-DNA association, an oxidative DNA damage, occurs in cells treated by Fe2+-DTPA and could result in cytotoxicity if not repaired.