Atkinson A, Roy D
Department of Environmental Health Science, University of Alabama, Birmingham 35294-008, USA.
Environ Mol Mutagen. 1995;26(1):60-6. doi: 10.1002/em.2850260109.
We have previously shown that bisphenol A (BPA) is oxidized to bisphenol-o-quinone in the presence of activation system and that the chemical reaction of DNA or deoxyguanosine 3'-monophosphate (dGMP) with bisphenol-o-quinone produces adducts. In the present study, using the 32P-postlabeling technique, we have investigated the in vivo DNA adduct formation by BPA by examining covalent modification in DNA. Administration of a single or multiple dose of 200 mg/kg of BPA to CD1 male rats produced two major and several minor adducts in liver DNA. The two major in vivo adducts matched the adduct profile of DNA or dGMP-bisphenol-o-quinone. To determine how BPA may be converted to DNA-binding metabolites, adducts were examined after incubation of DNA with BPA in the presence of a microsomal activation system. The in vitro incubation of BPA with DNA in the presence of a microsomal activation system revealed one major adduct and several minor adducts. The formation of adducts in DNA by BPA in the presence of a microsomal activation system was drastically decreased by known inhibitors of cytochrome P450. Adduct formation in DNA when cumene hydroperoxide or NADPH was used as a cofactor showed adducts with similar chromatographic mobilities as those from the reaction of dGMP-bisphenol-o-quinone. These data demonstrate that BPA is capable of binding covalently to DNA. DNA binding can be inhibited by the inhibitors of cytochrome P450. One of the DNA-binding metabolite(s) both in vitro and in vivo may be bisphenol-o-quinone. Covalent modifications in DNA by in vivo exposure of BPA may be a factor in the induction of hepatotoxicity.
我们之前已经表明，在活化系统存在的情况下，双酚A（BPA）会被氧化成双酚邻醌，并且DNA或脱氧鸟苷3'-单磷酸（dGMP）与双酚邻醌的化学反应会产生加合物。在本研究中，我们使用32P后标记技术，通过检测DNA中的共价修饰来研究BPA在体内形成DNA加合物的情况。给CD1雄性大鼠单次或多次给予200mg/kg的BPA后，在肝脏DNA中产生了两种主要加合物和几种次要加合物。这两种主要的体内加合物与DNA或dGMP - 双酚邻醌的加合物谱相匹配。为了确定BPA如何转化为与DNA结合的代谢产物，在微粒体活化系统存在的情况下，将DNA与BPA孵育后检测加合物。在微粒体活化系统存在的情况下，BPA与DNA的体外孵育显示出一种主要加合物和几种次要加合物。细胞色素P450的已知抑制剂可显著降低在微粒体活化系统存在的情况下BPA在DNA中形成加合物的量。当使用氢过氧化异丙苯或NADPH作为辅助因子时，DNA中加合物的形成显示出与dGMP - 双酚邻醌反应产生的加合物具有相似的色谱迁移率。这些数据表明BPA能够与DNA共价结合。细胞色素P450抑制剂可抑制DNA结合。体外和体内与DNA结合的代谢产物之一可能是双酚邻醌。BPA体内暴露导致的DNA共价修饰可能是诱导肝毒性的一个因素。
