title: Presence of N2-(deoxyguanosin-8-yl)-2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (dG-C8-MeIQx) in human tissues.
abstract: One of the mutagenic and carcinogenic heterocyclic amines (HCAs), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), is present in cooked foods and we are chronically exposed to this compound in our daily life. To study the role of HCAs in human carcinogenesis, we analyzed MeIQx-DNA adducts in 38 DNA samples obtained from surgical and autopsy specimens by the 32P-postlabeling method under adduct-intensification conditions with the modification of additional digestion with nuclease P1 and phosphodiesterase I after 32P-labeling at 5'-hydroxyl termini. This modified 32P-postlabeling method can detect N2-(deoxyguanosin-8-yl)-2-amino-3,8-dimethylimidazo- [4,5-f]quinoxaline 5'-monophosphate (5'-pdG-C8-MeIQx) at levels down to 1/10(10) nucleotides. The DNA samples from colon and rectum surgical specimens and a kidney taken at autopsy were found to contain an adduct spot corresponding to that of standard 5'-pdG-C8-MeIQx on TLC at levels of 14,18 and 1.8 per 10(10) nucleotides, respectively. Each adduct spot was extracted from TLC and identified to be 5'-pdG-C8-MeIQx by HPLC. Thus, MeIQx-DNA adducts actually exist in human tissues and this adduct formation may be involved in human cancer development.
authors.affiliation: Biochemistry Division, National Cancer Center Research Institute, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Totsuka
authors.forename: K
authors.initials: K
authors.lastname: Fukutome
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.forename: S
authors.initials: S
authors.lastname: Takahashi
authors.forename: A
authors.initials: A
authors.lastname: Tada
authors.forename: T
authors.initials: T
authors.lastname: Sugimura
authors.forename: K
authors.initials: K
authors.lastname: Wakabayashi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002273:Carcinogens / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D018736:DNA Adducts / Q000032:analysis*; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011810:Quinoxalines / Q000378:metabolism*
chemical_list: D002273:Carcinogens; D018736:DNA Adducts; D007093:Imidazoles; D011810:Quinoxalines; C036990:2-amino-3,8-dimethylimidazo(4,5-f)quinoxaline; C049584:2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine