Arif J M, Gupta R C
Preventive Medicine and Environmental Health, University of Kentucky Medical Center, Lexington 40536, USA.
Carcinogenesis. 1997 Oct;18(10):1999-2007. doi: 10.1093/carcin/18.10.1999.
Dibenzo[a,l]pyrene (DBP) is one of the most potent bacterial mutagen and mammary carcinogens. When DBP (50 microM) was incubated with calf thymus DNA (300 microg/ml) in the presence of liver microsomes from beta-naphthoflavone (beta-NF)- or Aroclor 1254-treated rats, at least eight adduct spots were detected as analyzed by nuclease P1-enhanced 32P-postlabeling assay. DNA adduction was enhanced by nearly 20- and 60-fold with beta-NF- and Aroclor 1254-induced microsomes, respectively, as compared with uninduced microsomes, suggesting a possible involvement of CYP1A family in DBP activation. Inclusion of the selective P4501A1 inhibitor, alpha-naphthoflavone (50 microM) in the activation reaction almost completely (>98%) abolished adduct formation further supporting involvement of P4501A in DBP activation. Analysis of DNA and 2'-deoxynucleosides 3'-mononucleotide reacted with anti- and syn-DBP-11,12-diol-13,14-epoxides (DBPDEs) and co-chromatography analyses in multiple solvents showed that the microsomal DBP-DNA adducts were derived by interaction of both anti- and syn-DBPDEs with adenine and guanine in DNA in the following order: anti-DBPDE-dA approximately syn-DBPDE-dG >> anti-DBPDE-dG approximately syn-DBPDE-dA. It is concluded that (i) most or all DBP adducts were P4501A-mediated; (ii) both the anti- and syn-stereoisomers were involved in the DNA adduct formation; and (iii) both adenine and guanine in the DNA contributed equally to the formation of the major and minor adducts.
二苯并[a,l]芘（DBP）是最具活性的细菌诱变剂和乳腺致癌物之一。当DBP（50微摩尔）在来自β-萘黄酮（β-NF）或艾氏剂1254处理大鼠的肝微粒体存在下与小牛胸腺DNA（300微克/毫升）一起孵育时，通过核酸酶P1增强的32P后标记分析检测到至少八个加合物斑点。与未诱导的微粒体相比，β-NF和艾氏剂1254诱导的微粒体使DNA加合分别增强了近20倍和60倍，这表明CYP1A家族可能参与了DBP的活化。在活化反应中加入选择性P4501A1抑制剂α-萘黄酮（50微摩尔）几乎完全（>98%）消除了加合物的形成，进一步支持了P4501A参与DBP活化。对与反式和顺式DBP-11,12-二醇-13,14-环氧化物（DBPDEs）反应的DNA和2'-脱氧核苷3'-单核苷酸进行分析，并在多种溶剂中进行共色谱分析，结果表明微粒体DBP-DNA加合物是由反式和顺式DBPDEs与DNA中的腺嘌呤和鸟嘌呤相互作用产生的，顺序如下：反式-DBPDE-dA≈顺式-DBPDE-dG>>反式-DBPDE-dG≈顺式-DBPDE-dA。得出的结论是：（i）大多数或所有DBP加合物是由P4501A介导的；（ii）反式和顺式立体异构体均参与了DNA加合物的形成；（iii）DNA中的腺嘌呤和鸟嘌呤对主要和次要加合物的形成贡献相同。
