Johnsen N M, Schwarze P E, Nyholm S H, Läg M, Becher R, Brunborg G, Holme J A
Department of Environmental Medicine, National Institute of Public Health, Oslo, Norway.
Carcinogenesis. 1997 Jan;18(1):193-9. doi: 10.1093/carcin/18.1.193.
The genotoxic effects of the environmental contaminants benz[j]aceanthrylene (B[j]A), benz[l]aceanthrylene (B[l]A) and benzo[a]pyrene (B[a]P), and the metabolism of radiolabelled B[j]A, were studied using rat lung microsomes and various types of isolated rat lung cells from control and Aroclor 1254 (PCB) treated animals. All three compounds (10 or 20 microg/plate) resulted in low, but detectable, levels of His+ revertants in the Salmonella assay when plated with control lung microsomes. The two cyclopenta polycyclic aromatic hydrocarbons (CP-PAH) B[j]A and B[l]A, gave increased levels of revertants when plated with microsomes from PCB-treated animals. Clara cells, type 2 cells and alveolar macrophages isolated from control rats were exposed to B[j]A, B[l]A or B[a]P (30 microg/ml, 1 h), but neither of the cell types showed any DNA damage when measured by alkaline filter elution. However, both B[j]A and B[l]A (30 microg/ml, 2 h) caused DNA adducts in all three cell types, measured by the 32P-post-labelling technique, whereas no B[a]P adducts were detected (30 microg/ml, 2 h). The total DNA adduct levels in Clara cells, type 2 cells and macrophages exposed to B[j]A were 0.085 +/- 0.033, 0.053 +/- 0.001 and 0.170 +/- 0.030 fmol/microg DNA, respectively, whereas the total levels in cells exposed to B[l]A were 0.140 +/- 0.070, 0.140 +/- 0.030 and 0.220 +/- 0.080 fmol/microg DNA, respectively. Cells exposed to B[j]A revealed only one adduct which corresponds with the B[j]A-1,2-oxide DNA adduct. Judged from high performance liquid chromatography (HPLC) analysis using radiolabelled B[j]A (30 microg/ml, 30 min), the major metabolite formed in control microsomes was B[j]A-1,2-diol. Thus, oxidation at the cyclopenta ring appears to be the most important activation pathway for B[j]A with control rat lung cells. Exposure of lung cells to CP-PAH (30 microg/ml, 2 h) isolated from PCB pretreated rats resulted in slightly increased DNA adduct levels in Clara cells and macrophages when compared to cells isolated from control rats. Furthermore, the adduct pattern had shifted, and no apparent B[j]A-1,2-oxide adduct could be detected on the thin layer chromatography (TLC) plate. In contrast, the major metabolite formed with microsomes from PCB-treated animals was still the B[j]A-1,2-diol.
利用大鼠肺微粒体以及从对照动物和经艾氏剂1254（多氯联苯）处理的动物中分离出的各类大鼠肺细胞，研究了环境污染物苯并[j]ace蒽（B[j]A）、苯并[l]ace蒽（B[l]A）和苯并[a]芘（B[a]P）的遗传毒性效应，以及放射性标记的B[j]A的代谢情况。当与对照肺微粒体一起铺板时，所有这三种化合物（10或20微克/平板）在沙门氏菌试验中均导致His+回复突变体水平较低，但可检测到。两种环戊稠合多环芳烃（CP-PAH）B[j]A和B[l]A，与经多氯联苯处理动物的微粒体一起铺板时，回复突变体水平增加。从对照大鼠分离出的克拉拉细胞、Ⅱ型细胞和肺泡巨噬细胞暴露于B[j]A、B[l]A或B[a]P（30微克/毫升，1小时），但通过碱性滤纸洗脱法测量时，没有一种细胞类型显示出任何DNA损伤。然而，通过32P后标记技术测量，B[j]A和B[l]A（30微克/毫升，2小时）在所有三种细胞类型中均导致DNA加合物形成，而未检测到B[a]P加合物（30微克/毫升，2小时）。暴露于B[j]A的克拉拉细胞、Ⅱ型细胞和巨噬细胞中的总DNA加合物水平分别为0.085±0.033、0.053±0.001和0.170±0.030飞摩尔/微克DNA，而暴露于B[l]A的细胞中的总水平分别为0.140±0.070、0.140±0.030和0.220±0.080飞摩尔/微克DNA。暴露于B[j]A的细胞仅显示一种与B[j]A-1,2-氧化物DNA加合物相对应的加合物。根据使用放射性标记的B[j]A（30微克/毫升，30分钟）的高效液相色谱（HPLC）分析判断，对照微粒体中形成的主要代谢产物是B[j]A-1,2-二醇。因此，对于对照大鼠肺细胞而言，环戊环上的氧化似乎是B[j]A最重要的活化途径。与从对照大鼠分离出的细胞相比，将肺细胞暴露于从经多氯联苯预处理的大鼠中分离出的CP-PAH（30微克/毫升，2小时）会导致克拉拉细胞和巨噬细胞中的DNA加合物水平略有增加。此外，加合物模式发生了变化，在薄层色谱（TLC）板上未检测到明显的B[j]A-1,2-氧化物加合物。相比之下，经多氯联苯处理动物的微粒体形成的主要代谢产物仍然是B[j]A-1,2-二醇。
