Etheno adducts in spleen DNA of SJL mice stimulated to overproduce nitric oxide

In order to investigate specific DNA damage caused by nitric oxide (NO) ind uced lipid peroxidation, levels of promutagenic etheno adducts 1,N-6-etheno deoxyadenosine (epsilon dA) and 3,N-4-ethenodeoxycytidine (epsilon dC) were measured in spleen DNA of SJL mice induced to produce high levels of NO by injection of RcsX (pre-B-cell lymphoma) cells. epsilon dA and epsilon dC l evels were quantified by an ultrasensitive immunoaffinity-P-32-post-labelin g method. Spleen DNA of control mice (n = 5) had background levels of 9.2 /- 5.4 epsilon dA adducts per 10(9) dA and 13.1 +/- 5.7 epsilon dC adducts per 10(9) dC, In RcsX cell-injected mice (n = 7), levels of these adducts w ere elevated similar to 6-fold, i.e, 53.9 +/- 39.4 epsilon dA per 10(9) dA and 83.5 +/- 57.8 epsilon dC per 10(9) dC (P < 0.05). Mice injected with Rc sX cells and also treated with N-G-methyl-L-arginine (NMA), an inhibitor of inducible nitric oxide synthase (n = 6), had significantly reduced levels (P < 0.05) of both epsilon dA and epsilon dC (13.5 +/- 5.7 epsilon dA per 1 0(9) dA and 28.2 +/- 15.7 epsilon dC per 10(9) dC), These findings constitu te the first available evidence of formation of etheno adducts associated w ith NO overproduction irt vivo. The adducts were presumably formed from lip id peroxidation products such as trans-4-hydroxy-2-nonenal (HNE), generated via oxidation of lipids by peroxynitrite. The results suggest that etheno- DNA adducts, among other types of damage, may contribute to the etiology of cancers associated with chronic infection/inflammation in which NO is over produced.