Mahadevan Brinda, Marston Charis P, Dashwood Wan-Mohaiza, Li Yonghai, Pereira Clifford, Baird William M
Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon 97331, USA.
Chem Res Toxicol. 2005 Feb;18(2):224-31. doi: 10.1021/tx0497604.
A complex mixture of polycyclic aromatic hydrocarbons (PAH) extracted from coal tar, standard reference material (SRM) 1597, has been shown to initiate tumor formation in mouse initiation-promotion assays in our laboratory [(2001) Carcinogenesis 22 (7), 1077-1086]. To determine the effects of SRM 1597 on PAH activation in human cells, we investigated the PAH-DNA adduct formation in the human mammary carcinoma-derived cell line MCF-7. We examined the effects of SRM 1597 on the metabolic activation to DNA binding derivatives of two carcinogenic PAHs, the bay region containing benzo[a]pyrene (B[a]P) and the more carcinogenic fjord region containing dibenzo[a,l]pyrene (DB[a,l]P). PAH-DNA adduct analysis by 33P-postlabeling and reversed phase high-performance liquid chromatography revealed a significant decrease in the levels of both B[a]P and DB[a,l]P DNA adduct formation on cotreatment with SRM 1597 in comparison to cells exposed to B[a]P or DB[a,l]P alone. However, the inhibition of PAH-DNA adduct formation only occurred within the first 48 h of exposure in cells cotreated with SRM 1597 and B[a]P. In contrast, SRM 1597 significantly inhibited the level of DB[a,l]P DNA adducts throughout the 120 h of exposure. Induction of human cytochrome P450 (P450) enzymes 1A1 and P4501B1 on treatment with SRM 1597 was observed by immunoblots. These results suggest that the important factors in determining the carcinogenic activity of PAH within a complex mixture would depend on the ability of other components of the mixture to promote or inhibit the activation of carcinogenic PAH by the induction of P450 enzymes followed by the formation of DNA adducts.
从煤焦油中提取的多环芳烃（PAH）复杂混合物——标准参考物质（SRM）1597，在我们实验室的小鼠启动-促进试验中已被证明可引发肿瘤形成[（2001年）《癌变》22（7），1077 - 1086]。为了确定SRM 1597对人细胞中PAH激活的影响，我们研究了人乳腺癌衍生细胞系MCF - 7中PAH - DNA加合物的形成。我们检测了SRM 1597对两种致癌PAH代谢激活为DNA结合衍生物的影响，一种是含苯并[a]芘（B[a]P）的湾区PAH，另一种是更具致癌性的含二苯并[a,l]芘（DB[a,l]P）的峡湾区PAH。通过33P后标记和反相高效液相色谱法进行的PAH - DNA加合物分析显示，与单独暴露于B[a]P或DB[a,l]P的细胞相比，在与SRM 1597共同处理时，B[a]P和DB[a,l]P的DNA加合物形成水平均显著降低。然而，PAH - DNA加合物形成的抑制仅发生在与SRM 1597和B[a]P共同处理的细胞暴露的前48小时内。相比之下，在整个120小时的暴露过程中，SRM 1597显著抑制了DB[a,l]P DNA加合物的水平。通过免疫印迹观察到用SRM 1597处理后诱导了人细胞色素P450（P450）酶1A1和P4501B1。这些结果表明，在确定复杂混合物中PAH致癌活性的重要因素将取决于混合物中其他成分通过诱导P450酶继而形成DNA加合物来促进或抑制致癌PAH激活的能力。
