Spectra of Mutations Induced by Structurally-Related Aromatic Polycyclic Carcinogens during Replication of a Shuttle Vector in Human Cells

摘要: We are comparing the kinds and spectra of mutations induced when DNA containing covalently bound carcinogen residues (adducts) replicates in human cells. A shuttle vector, pZ189, carrying supF gene coding for a bacterial tyrosine suppressor tRNA as target was treated with tritiated polycyclic aromatic carcinogens number adducts per plasmid determined. The plasmids were trarsfected into cells, after replication had occurred, progeny rescued assayed frequency mutants. studied included 7,8-diol-9,10-epoxide benzo[a]pyrene (BPDE), 1nitrosopyrene (1-NOP), N-acetoxy-2-acetylaminofluorene (N-AcO-AAF), its trifluoroacetyl derivative (N-AcO-TFA-AF). BPDE binds principally to N2 position guanine. other three bind C8 Each agent caused linear increase mutants function formed, reaching frequencies high 20 x 10-4 40 10-4, above background 1.4 10-4. When compared on basis approximately four times more mutagenic than carcinogens. This difference may reflect intrinsic differences nature their location molecule, but it also rate removal particular by nucleotide excision repair since we showed that host cells excise from genomic at least slower they 1-NOP adducts. Agarose gel electrophoresis sequencing analysis derived untreated majority (70%) involved deletions, insertions, or altered mobility (gross rearrangements). In contrast, those base substitutions. 86 unequivocally independent 60 indicated 70% 80% contained single substitution, 5%-10% two substitutions, 4%-10% small insertions deletions (one pairs). (83%) substitutions transversions, predominantly G•C→T•A.These produced own spectrum mutations. Studies date N-AcO-TFA-AF have shown AF adduct induces subsitutions all these involve