Selzer R R, Elfarra A A
Department of Comparative Biosciences and Environmental Toxicology Center, University of Wisconsin, Madison 53706, USA.
Carcinogenesis. 1999 Feb;20(2):285-92. doi: 10.1093/carcin/20.2.285.
We have previously shown that butadiene monoxide (BM), the primary metabolite of 1,3-butadiene, reacted with nucleosides to form alkylation products that exhibited different rates of formation and different stabilities under in vitro physiological conditions. In the present study, BM was reacted with single-stranded (ss) and double-stranded (ds) calf thymus DNA and the alkylation products were characterized after enzymatic hydrolysis of the DNA. The primary products were regioisomeric N-7-guanine adducts. N-3-(2-hydroxy-3-buten-1-yl)adenine and N-3-(1-hydroxy-3-buten-2-yl)adenine, which were depurinated from the DNA more rapidly than the N-7-guanine adducts, were also formed. In addition, N6-(2-hydroxy-3-buten-1-yl)deoxyadenosine and N6-(1-hydroxy-3-buten-2-yl)deoxyadenosine were detected and evidence was obtained that these adducts were formed by Dimroth rearrangement of the corresponding N-1-deoxyadenosine adducts, not while in the DNA, but following the release of the N-1-alkylated nucleosides by enzymatic hydrolysis. N-3-(2-hydroxy-3-buten-1-yl)deoxyuridine adducts, which were apparently formed subsequent to deamination reactions of the corresponding deoxycytidine adducts, were also detected and were stable in the DNA. Adduct formation was linearly dependent upon BM concentration (10-1000 mM), with adduct ratios being similar at the various BM concentrations. At a high BM concentration (750 mM), the adducts were formed in a linear fashion for up to 8 h in both ssDNA and dsDNA. However, the rates of formation of the N-3-deoxyuridine and N6-deoxyadenosine adducts increased 10- to 20-fold in ssDNA versus dsDNA, whereas the N-7-guanine adducts increased only slightly, presumably due to differences in hydrogen bonding in ssDNA versus dsDNA. These results may contribute to a better understanding of the molecular mechanisms of mutagenesis and carcinogenesis of both BM and its parent compound, 1,3-butadiene.
我们之前已经表明，1,3 - 丁二烯的主要代谢产物一氧化丁二烯（BM）与核苷反应形成烷基化产物，这些产物在体外生理条件下表现出不同的形成速率和不同的稳定性。在本研究中，BM与单链（ss）和双链（ds）小牛胸腺DNA反应，并在DNA酶解后对烷基化产物进行表征。主要产物是区域异构体N - 7 - 鸟嘌呤加合物。还形成了N - 3 -（2 - 羟基 - 3 - 丁烯 - 1 - 基）腺嘌呤和N - 3 -（1 - 羟基 - 3 - 丁烯 - 2 - 基）腺嘌呤，它们从DNA中脱嘌呤的速度比N - 7 - 鸟嘌呤加合物更快。此外，检测到N6 -（2 - 羟基 - 3 - 丁烯 - 1 - 基）脱氧腺苷和N6 -（1 - 羟基 - 3 - 丁烯 - 2 - 基）脱氧腺苷，并获得证据表明这些加合物是由相应的N - 1 - 脱氧腺苷加合物的迪莫夫重排形成的，不是在DNA中形成，而是在通过酶解释放N - 1 - 烷基化核苷之后形成。还检测到N - 3 -（2 - 羟基 - 3 - 丁烯 - 1 - 基）脱氧尿苷加合物，它们显然是在相应的脱氧胞苷加合物脱氨反应之后形成的，并且在DNA中稳定。加合物的形成与BM浓度（10 - 1000 mM）呈线性相关，在不同的BM浓度下加合物比例相似。在高BM浓度（750 mM）下，ssDNA和dsDNA中的加合物均以线性方式形成长达8小时。然而，ssDNA中N - 3 - 脱氧尿苷和N6 - 脱氧腺苷加合物的形成速率比dsDNA中增加了10至20倍，而N - 7 - 鸟嘌呤加合物仅略有增加，这可能是由于ssDNA和dsDNA中氢键的差异所致。这些结果可能有助于更好地理解BM及其母体化合物1,3 - 丁二烯的诱变和致癌分子机制。
