Metabolism of benzo(a)pyrene by isolated hepatocytes and factors affecting covalent binding of benzo(a)pyrene metabolites to DNA in hepatocyte and microsomal systems.
Metabolism of benzo(a)pyrene by isolated hepatocytes and factors affecting covalent binding of benzo(a)pyrene metabolites to DNA in hepatocyte and microsomal systems.
复制标题
分离的肝细胞对苯并 (a) 芘的代谢以及影响肝细胞和微粒体系统中苯并 (a) 芘代谢物与 DNA 共价结合的因素。
DOI：
10.1016/0003-9861(80)90063-6
复制
发表时间：
1980
影响因子：
3.9
通讯作者：
Jefcoate,CR
中科院分区：
文献类型：
--
作者：
Shen,AL;Fahl,WE;Jefcoate,CR
研究了苯并(A)芘(BP)代谢产物与DNA在肝细胞和肝微体(MC微体)中的共价结合。BP在肝细胞和小牛胸腺DNA与MC-微粒子孵育过程中形成的加合物主要是反式-7，8，-dihydroxy-9，10-epoxy-7，8，9，10-tetrahydrobenzo(a)pyrene(二醇-环氧化物)和BP-9-苯酚的环氧化物(苯酚-氧化物)的加合物。在肝细胞中，二醇-环氧化物加合物比苯酚-氧化物加合物占优势，而在微粒体孵育中则相反。在肝细胞中，二醇-环氧化物加合物和酚氧化物加合物均随BP浓度的增加而增加，在30~10 0μ血压范围内，二醇-环氧化物加合物与酚氧化物加合物的比例从6：1降至3：1。在微粒体孵育中，DNA浓度的降低或肝细胞L15培养液的加入使酚氧化物加合物的降幅大于二醇环氧化物加合物的降幅。抑制剂水杨酰胺、马来酸二乙酯和3，3，3-三氯丙烯氧化物对BP-DNA加合物形成的影响从前体形成和代谢的变化以及肝细胞谷胱甘肽水平的降低来解释。在肝细胞孵育中加入1.5 mg/ml外源DNA，即使胞外BP-DNA加合物占总加合物的97%，但与细胞DNA的共价结合没有变化。对于胞外和胞内DNA，二醇-环氧化物和苯酚-氧化物加合物的相对数量以及每毫克DNA的总加合物都是无法区分的。用二醇环氧化物修饰细胞外DNA的效率至少与在MC微体孵育中修饰小牛胸腺DNA的效率相同。结果表明，BP二醇环氧化物和苯酚氧化物可以同样方便地离开细胞或进入细胞核，但更有效地与产生它们的细胞中的DNA结合。
Covalent binding of benzo(a)pyrene (BP) metabolites to DNA was investigated in hepatocytes and liver microsomes (MC-microsomes) isolated from 3-methylcholanthrene-treated rats. The major DNA adducts formed during BP metabolism in both hepatocytes and incubations of calf thymus DNA with MC-microsomes were adducts ofantiandsynisomers oftrans-7,8,-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (diol-epoxides) and of epoxide derivatives of BP-9-phenol (phenol-oxides). Diol-epoxide adducts predominated over phenol-oxide adducts in hepatocytes, while the reverse was found in microsomal incubations. In hepatocytes, both diol-epoxide and phenol-oxide adducts increased with increasing BP concentration; the ratio of diol-epoxide adduct to phenol-oxide adduct decreased from 6:1 to 3:1 between 30 and 100 μmBP. In microsomal incubations, decreases in DNA concentration or addition of the hepatocyte L15 medium produced larger decreases in phenol-oxide adducts than in diol-epoxide adducts. The effects of the inhibitors salicylamide, diethylmaleate, and 3,3,3,-trichloropropene oxide on formation of BP-DNA adducts are interpreted in terms of changes in precursor formation and metabolism and reductions in hepatocyte glutathione levels. Addition of 1.5 mg/ml exogenous DNA to hepatocyte incubations produced no change in covalent binding to cellular DNA, even though extracellular BP-DNA adducts accounted for 97% of the total adducts formed. Both the relative amounts of diol-epoxide and phenol-oxide adducts and the total adducts per milligram of DNA were indistinguishable with respect to extracellular and intracellular DNA. Modification of extracellular DNA by diol-epoxides was at least as efficient as modification of calf thymus DNA in incubations with MC-microsomes. It is concluded that BP diol-epoxides and phenol-oxides can leave the cell or enter the nucleus with equal facility but are more effective in binding to DNA in the cell in which they are generated.