Mutations induced by aromatic amine DNA adducts in pBR322

Abstract

A 276 bp region from the tetracycline resistance gene of the plasmid pBR322 was modified with 2-acetylaminofluorene (AAF), 2-aminofluorene (AF), 4-aminobiphenyl (ABP), N'-acetylbenzidine or 1-aminopyrene (AP) in order to determine the effect of adduct structure upon mutation induction. Each modification reaction gave one major adduct and these adducts had chromatographic properties, as determined by 32P-postlabeling, identical to those in which substitution had occurred at C8 of deoxyguanosine through the amine or amide nitrogen. The types and distribution of mutations were then characterized following introduction of the modified plasmids into SOS-induced Escherichia coli using Hanahan et al.'s procedure (Methods Enzymol., 204, 63-113, 1991). With AAF-modified plasmid, 60% of the mutations were deletions or additions, and these were detected primarily at NarI sites or in repetitive G sequences. Modification with AF gave -G deletions, primarily in runs of Gs, and base substitution mutations, which were mainly G to T transversions. Substitution with ABP or N'-acetylbenzidine resulted in G to T and G to C transversions, the latter being a mutation not detected with AF; in addition, -G deletions were detected at only very low frequency. AP modification gave both -G frameshift and base substitution mutations, of which G to T transversions predominated. A comparison of the mutation frequencies per adduct indicated that the mutagenic efficiencies of the adducts decreased in the order AP > AF > AAF approximately ABP approximately N'-acetylbenzidine. AAF- and ABP-modified pBR322 were also introduced with a CaCl2 method. The mutation frequency per adduct increased with this transformation procedure, and this appeared to be a reflection of a greater percentage of frameshift mutations. These data indicate that a series of structurally related aromatic amines will induce both base substitution and frameshift mutations when incorporated into pBR322, but that frameshift mutations occur almost exclusively with the planar derivatives. Furthermore, the ability to induce frameshift mutations increases the mutagenic efficiency of an adduct.

Organ Specificity of the Bladder Carcinogen 4-Aminobiphenyl in Inducing DNA Damage and Mutation in Mice

“…In addition, 4-ABP is weakly but significantly mutagenic in the kidney and liver of carcinogen-treated mice. Of significance, the spectrum of mutations produced in the bladder of 4-ABP-treated mice perfectly reflects the known mutagenic potentials of 4-ABP-DNA adducts (38,42,43,(48)(49)(50). Altogether, our findings support the etiologic involvement of 4-ABP in the genesis of bladder cancer and provide a perspective on how DNA adduction leading to mutagenesis, which is specifically targeted to bladder urothelial cells, may account for bladder-tumorigenicity of this carcinogen.…”

“…The "syn" conformation places the O6 and N7 atoms of the modified guanine in a position to mispair with N6 and N1 atoms of an adenine or with N1 and N2 atoms of a guanine in the complementary strand, thus, resulting in G!T or G!C transversion mutations, respectively (46,47). In vitro and/or in vivo studies in various model systems have shown that 4-ABP or its metabolites induce both G:C!T:A and G:C!C:G transversion mutations, with the former being the most prominent type of mutation (38,42,43,(48)(49)(50). Furthermore, mutation analysis of the TP53 gene in human bladder tumors has shown that G:C!A:T transition mutations are the prevalent type of mutation found in the general population or specifically in individuals with known history of exposure to aromatic amines (43).…”

4‐Aminobiphenyl induces liver DNA adducts in both neonatal and adult mice but induces liver mutations only in neonatal mice

“…51 The major DNA adduct was identified as N-(deoxyguanosin-8-yl)-4-ABP, 20 which has been shown to result in G:CfiT:A mutation. 50 Furthermore, in B6C3F 1 mice, 85% of 4-ABP-induced tumors had G:CfiT:A mutation in H-ras codon 61. 43 Our sequencing data also suggest that clonal expansion does not play a crucial role for the MF induced by 4-ABP in neonatal mice.…”

Tobacco smoke carcinogens, DNA damage and p53 mutations in smoking-associated cancers

“…GC?TA mutations are also the predominant ones observed in studies of mutagenesis by N 2 -deoxyguanosine adducts of 1,3-butadiene (Carmical et al, 2000), adducts of 4-aminobiphenyl (Melchior et al, 1994), and 8-oxodeoxyguanosine (Moriya, 1993). Other studies of butadiene mutagenesis demonstrate the occurrence of GC?AT, AT?TA, and GC?TA mutations (Recio et al, 2000).…”