Mn. Routledge et al., MUTATIONS INDUCED BY SATURATED AQUEOUS NITRIC-OXIDE IN THE PSP189 SUPF GENE IN HUMAN AD293 AND ESCHERICHIA-COLI MBM7070 CELLS, Carcinogenesis, 14(7), 1993, pp. 1251-1254
Nitric oxide is an important bioregulatory agent that may also be an e
ndogenous and exogenous human mutagen. In order to study mutations gen
erated following exposure of a shuttle vector-borne target gene to nit
ric oxide, mutations were induced in the supF gene of the pSP189 shutt
le vector by treatment with nitric oxide in aerobic buffered solution
followed by replication of the plasmid in either human Ad293 or Escher
ichia coli MBM7070 cells. The induced mutation frequency, which increa
sed with nitric oxide dose, was 44-fold greater than the spontaneous b
ackground in human cells and > 15-fold greater than background in the
bacterial cells when a total of 100 mmol of nitric oxide was oxidative
ly absorbed/l of pH 7.4 buffer containing the plasmid. The majority of
point mutations analysed (61 and 75% for human and E. coli cells resp
ectively) were AT-->6GC transitions with GC-->AT transitions (29 and 2
3%) being the next most prevalent. The overall frequencies of the vari
ous point mutations seen in the supF gene were similar in the two cell
types, although the distribution of hotspots showed differences. The
results are consistent with a mutational mechanism initiated by deamin
ation of DNA bases.