MUTATION SPECTRUM OF CIGARETTE-SMOKE CONDENSATE IN SALMONELLA - COMPARISON TO MUTATIONS IN SMOKING-ASSOCIATED TUMORS

We used colony probe hybridization and polymerase chain reaction/DNA s equence analysis to determine the mutations in similar to 1600 reverta nts of Salmonella induced by cigarette smoke condensate (CSC) in the p resence of S9, CSC induced similar to 80% GC --> TA transversions and similar to 20% GC --> AT transitions at the base-substitution allele ( hisG46) in strain TA100. This spectrum was similar to those of the pol ycyclic aromatic hydrocarbon (PAD) benzo[a]pyrene and various aromatic amines such as 4-aminobiphenyl and Glu-P-1, all of which are present in CSC, This spectrum was also similar to that produced by PAHs in oth er bacteria, mammalian cells, and rodents as well as to that of the p5 3 gene in lung tumors from smokers. The results in Salmonella are cons istent with a role for the PAH component of cigarette smoke in the bas e-substitution specificity found in the p53 gene of smoking-associated lung tumors, At the frameshift allele in strains TA1538 and TA98, CSC induced only a hotspot 2-base deletion, which is a mutation spectrum that is identical to that induced by the heterocyclic amine pyrolysate products of amino acids, such as Glu-P-1. This is consistent with bio assay-directed fractionation studies showing that aromatic amines acco unt for most of the frameshift specificity of CSC in Salmonella. Roden t and human studies indicate that aromatic amines are responsible for smoking-associated bladder cancer, Repeated freezing and thawing of th e CSC samples changed the chemical composition of the mixtures as evid enced by the production of an altered mutation spectrum, This emphasiz es the necessity of proper storage and handling of labile complex mixt ures, This study (i) confirms our previous studies showing that the mu tation spectrum of a complex mixture reflects the dominance of one or a few classes of chemical mutagens within the mixture, and (ii) illust rates the potential of bioassay-directed molecular analysis for identi fying the chemical classes in a complex mixture that are responsible f or specific classes of mutation and tumor types produced by the mixtur e.