Deletion and single nucleotide substitution at G:C in the kidney of gpt delta transgenic mice after ferric nitrilotriacetate treatment.
An iron chelate, ferric nitrilotriacetate (Fe-NTA), induces oxidative renal proximal tubular damage that subsequently leads to a high incidence of renal cell carcinoma in rodents, presenting an intriguing model of free radical-induced carcinogenesis. In the present study, we used gpt delta transgenic mice, which allow efficient detection of point mutations and deletions in vivo, to evaluate the mutation spectra, in association with the formation of 8-oxoguanine and acrolein-modified adenine during the first 3 weeks of carcinogenesis. Immunohistochemical analysis revealed the highest levels of 8-oxoguanine and acrolein-modifed adenine in the renal proximal tubules after 1 week of repeated administration. DNA immunoprecipitation and quantitative polymerase chain reaction analysis showed that the relative abundance of 8-oxoguanine and acrolein-modified adenine at the gpt reporter gene were increased at the first week in the kidney. Similarly, in both 6-thioguanine and Spi(-) selections performed on the renal specimens after Fe-NTA administration, the mutant frequencies were increased in the Fe-NTA-treated mice at the first week. Further analyzes of 79 mutant clones and 93 positive plaques showed a high frequency of G:C pairs as preferred targets for point mutation, notably G:C to C:G transversion-type mutation followed by deletion, and of large-size (>1 kilobase) deletions with short homologous sequences in proximity to repeated sequences at the junctions. The results demonstrate that the iron-based Fenton reaction is mutagenic in vivo in the renal tubular cells and induces characteristic mutations.
Jiang
Li
L
Department of Pathology and Biology of Diseases, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
Zhong
Yi
Y
Akatsuka
Shinya
S
Liu
Yu-Ting
YT
Dutta
Khokon Kumar
KK
Lee
Wen-Hua
WH
Onuki
Janice
J
Masumura
Ken-ichi
K
Nohmi
Takehiko
T
Toyokuni
Shinya
S
D000818:Animals; D001483:Base Sequence; D002273:Carcinogens / Q000633:toxicity*; D004249:DNA Damage; D004252:DNA Mutational Analysis; D029968:Escherichia coli Proteins / Q000235:genetics*; D005290:Ferric Compounds / Q000633:toxicity*; D047468:Immunoprecipitation; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism; D007680:Kidney Neoplasms / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009571:Nitrilotriacetic Acid / Q000031:analogs & derivatives* / Q000633:toxicity; D010430:Pentosyltransferases / Q000235:genetics*; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D017384:Sequence Deletion
D002273:Carcinogens; D029968:Escherichia coli Proteins; D005290:Ferric Compounds; D010430:Pentosyltransferases; C071962:Gpt protein, E coli; D009571:Nitrilotriacetic Acid; C020326:ferric nitrilotriacetate