Jk. Sandhu et Hc. Birnboim, MUTAGENICITY AND CYTOTOXICITY OF REACTIVE OXYGEN AND NITROGEN SPECIESIN THE MN-11 MURINE TUMOR-CELL LINE, Mutation research, 379(2), 1997, pp. 241-252
There is increasing evidence that endogenously generated reactive oxyg
en (ROS) and reactive nitrogen (RNS) species at sites of inflammation
and in tumors may be genotoxic. We have developed a murine tumor model
(MN-11) in which mutations at the hypoxanthine phosphoribosyltransfer
ase (HPRT) locus, arising both in vitro and in vivo, can be detected.
In the present report, we describe an in vitro study of the ability of
ROS and RNS to induce mutations in our model system. Cs-137 radiation
and radiomimetic drugs caused a dose-dependent increase in mutant fre
quency. At D-0, radiation induced about 170 mutants per 10(5) viable c
ells, compared to 50 and 95 for streptonigrin and bleomycin, respectiv
ely. H2O2 induced a lower frequency of mutants, 20-30 per 10(5) for en
zymatically generated or bolus, respectively. For the following treatm
ents, mutant frequency at 50% survival is shown. Incubation with human
granulocytes induced a low frequency of mutants (about 15 per 10(5)).
RNS was tested using a series of NO-donating drugs. Spermine/NO . ind
uced cytotoxicity but no mutants while S-nitroso-N-acetylpenicillamine
induced a low level, 10 per 10 Both release nitrogen monoxide spontan
eously, with a t(1/2) < 3 h. Glyceryl trinitrate and sodium nitropruss
ide are two drugs that were slowly metabolized by MN-11 cells (> 12 h)
. Glyceryl trinitrate induced about 20 per 10(5) while nitroprusside i
nduced 50 per 10(5). Our results indicate that RNS can readily induce
mutations detectable in MN-11 cells. At equicytotoxic doses, the induc
ed mutant frequency varied considerably for different drugs, suggestin
g that different states of nitrogen monoxide (such as NO+ or NO .) may
be generated and these may vary in their mutagenic/cytotoxic potentia
l. (C) 1997 Elsevier Science B.V.