Evidence that a burst of DNA depurination in SENCAR mouse skin induces error-prone repair and forms mutations in the H-ras gene

• Published in: Oncogene Vol. 20; no. 55; pp. 7945 - 7953
• Main Authors: CHAKRAVARTI, Dhrubajyoti, MAILANDER, Paula C, LI, Kai-Ming, HIGGINBOTHAM, Sheila, ZHANG, Henry L, GROSS, Michael L, MEZA, Jane L, CAVALIERI, Ercole L, ROGAN, Eleanor G
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing 29.11.2001; Nature Publishing Group
• Subjects: 17β-Estradiol; Adducts; Animals; Base Sequence; Biological and medical sciences; Carcinogens; Cell cycle; Deoxyribonucleic acid; DNA; DNA Adducts - chemistry; DNA Adducts - drug effects; DNA Adducts - genetics; DNA damage; DNA Damage - drug effects; DNA Damage - genetics; DNA glycosylase; DNA Mutational Analysis; DNA Repair - drug effects; DNA Repair - genetics; Estradiol - analogs & derivatives; Estradiol - chemistry; Estradiol - pharmacology; estradiol-3,4-quinone; Female; Fundamental and applied biological sciences. Psychology; Genes, ras - genetics; Genotoxicity; H-ras gene; H-Ras protein; Hras gene; Mice; Mice, Inbred SENCAR; Molecular and cellular biology; Mutagenesis - genetics; Mutagens - chemistry; Mutagens - pharmacology; Mutation; Nucleic Acid Heteroduplexes - drug effects; Nucleic Acid Heteroduplexes - genetics; Point Mutation - genetics; Polymerase Chain Reaction; Quinones; Ras protein; Skin; Skin - drug effects; Skin - metabolism; United States > US; Nebraska; Excision; Rodentia; Error; Carcinogenesis; Carcinogen; Vertebrata; Mammalia; Treatment; Mouse; Animal; DNA; Early; Skin; Mutation; Ras gene; Repair
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/sj.onc.1204969

Treatment of SENCAR mouse skin with dibenzo[a,l]pyrene results in abundant formation of abasic sites that undergo error-prone excision repair, forming oncogenic H-ras mutations in the early preneoplastic period. To examine whether the abundance of abasic sites causes repair infidelity, we treated SENCAR mouse skin with estradiol-3,4-quinone (E(2)-3,4-Q) and determined adduct levels 1 h after treatment, as well as mutation spectra in the H-ras gene between 6 h and 3 days after treatment. E(2)-3,4-Q formed predominantly (> or =99%) the rapidly-depurinating 4-hydroxy estradiol (4-OHE(2))-1-N3Ade adduct and the slower-depurinating 4-OHE(2)-1-N7Gua adduct. Between 6 h and 3 days, E(2)-3,4-Q induced abundant A to G mutations in H-ras DNA, frequently in the context of a 3'-G residue. Using a T.G-DNA glycosylase (TDG)-PCR assay, we determined that the early A to G mutations (6 and 12 h) were in the form of G.T heteroduplexes, suggesting misrepair at A-specific depurination sites. Since G-specific mutations were infrequent in the spectra, it appears that the slow rate of depurination of the N7Gua adducts during active repair may not generate a threshold level of G-specific abasic sites to affect repair fidelity. These results also suggest that E(2)-3,4-Q, a suspected endogenous carcinogen, is a genotoxic compound and could cause mutations.