Ochiai M, Nagaoka H, Wakabayashi K, Tanaka Y, Kim S B, Tada A, Nukaya H, Sugimura T, Nagao M
Carcinogenesis Division, National Cancer Center Research Institute, Tokyo, Japan.
Carcinogenesis. 1993 Oct;14(10):2165-70. doi: 10.1093/carcin/14.10.2165.
The carcinogenic heterocyclic amine 2-amino-3,8-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx) is widely distributed in cooked foods. The nuclease P1 method increased the sensitivity of the standard 32P-postlabeling analysis about 1000-fold for detection of MeIQx-DNA adducts. The recovery of MeIQx-DNA adducts by the nuclease P1 method was determined to be about 50% using liver DNA of a rat treated with [14C]MeIQx intragastrically. By the nuclease P1 method five adducts were detected in the liver DNA of rats fed MeIQx and two of them, including the most abundant one, were identified as MeIQx-deoxyguanosine adducts by comparison with the adducts formed in in vitro reactions of N-acetoxy-2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline with the four 2'-deoxyribonucleotides. The most abundant adduct in vivo was identified as N2-(deoxyguanosin-8-yl)-MeIQx 3',5'-diphosphate (3',5'-pdGp-C8-MeIQx). MeIQx-DNA adduct levels in human tissues could be determined by the nuclease P1 modification of the 32P-postlabeling method in combination with HPLC, and thus provide information on the roles of MeIQx in human carcinogenesis.
致癌杂环胺2-氨基-3,8-二甲基咪唑并[4,5-f]喹喔啉（MeIQx）广泛分布于熟食中。核酸酶P1法可将标准的32P后标记分析检测MeIQx-DNA加合物的灵敏度提高约1000倍。使用经胃内给予[14C]MeIQx处理的大鼠肝脏DNA，通过核酸酶P1法测定MeIQx-DNA加合物的回收率约为50%。通过核酸酶P1法在喂食MeIQx的大鼠肝脏DNA中检测到五种加合物，其中两种，包括含量最高的一种，通过与N-乙酰氧基-2-氨基-3,8-二甲基咪唑并[4,5-f]喹喔啉与四种2'-脱氧核糖核苷酸的体外反应形成的加合物进行比较，被鉴定为MeIQx-脱氧鸟苷加合物。体内含量最高的加合物被鉴定为N2-（脱氧鸟苷-8-基）-MeIQx 3',5'-二磷酸（3',5'-pdGp-C8-MeIQx）。人体组织中的MeIQx-DNA加合物水平可通过32P后标记法的核酸酶P1修饰结合高效液相色谱法测定，并因此提供有关MeIQx在人类致癌作用中作用的信息。
