Pharmacology and Toxicology Graduate Program, Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Pharmacology and Toxicology Graduate Program, Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Toxicology. 2014 Jul 3;321:21-6. doi: 10.1016/j.tox.2014.03.004. Epub 2014 Mar 24.
Carcinogenicity of the mycotoxin aflatoxin B1 (AFB1), which is produced by Aspergillus fungi, is associated with bioactivation of AFB1 to AFB1-8,9-exo-epoxide and formation of DNA adducts. However, AFB1 also causes 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation in mouse lung DNA, suggesting that oxidative DNA damage may also contribute to AFB1 carcinogenicity. The oxidative DNA damage 5-hydroxy-2'-deoxycytidine (5-OHdC) may also contribute to AFB1 carcinogenicity. The objective of the present study was to determine the effect of treatment of mice with AFB1 on pulmonary and hepatic: 8-OHdG and 5-OHdC levels; base excision repair (BER, which repairs oxidative DNA damage) activities; and on levels of 8-oxoguanine DNA glycosylase (OGG1, the rate-limiting enzyme in the BER of 8-OHdG). Female A/J mice were treated with vehicle (dimethyl sulfoxide) or 50 mg/kg AFB1 ip. Oxidative DNA damage was measured using HPLC with electrochemical detection, BER activity was assessed using an in vitro assay that employs a substrate plasmid DNA with 8-OHdG lesions, and OGG1 protein levels were determined by immunoblotting. Two hours post treatment, AFB1 increased 8-OHdG levels in mouse lung DNA by approximately 69% relative to control (p<0.05), but did not alter 8-OHdG levels in liver or 5-OHdC levels in lung or liver (p>0.05). AFB1 treatment also increased BER activity in mouse lung by approximately 87% (p<0.05) but did not affect hepatic BER activity (p>0.05). Levels of OGG1 immunoreactive protein were increased in both lung (20%) and liver (60%) (p<0.05). These results are consistent with oxidative DNA damage contributing to the carcinogenicity of AFB1 in this model.
黄曲霉毒素 B1（AFB1）是一种由曲霉菌产生的真菌毒素，具有致癌性。这种致癌性与 AFB1 向 AFB1-8,9-外环氧和 DNA 加合物的生物转化有关。然而，AFB1 也会导致小鼠肺 DNA 中 8-羟基-2'-脱氧鸟苷（8-OHdG）的形成，这表明氧化 DNA 损伤也可能导致 AFB1 的致癌性。氧化 DNA 损伤 5-羟基-2'-脱氧胞苷（5-OHdC）也可能导致 AFB1 的致癌性。本研究的目的是确定用 AFB1 处理小鼠对肺和肝：8-OHdG 和 5-OHdC 水平；碱基切除修复（BER，修复氧化 DNA 损伤）活性；以及 8-氧鸟嘌呤 DNA 糖基化酶（OGG1，BER 中 8-OHdG 的限速酶）的水平的影响。用 DMSO 或 50mg/kg AFB1 对 A/J 雌性小鼠进行腹腔注射处理。用 HPLC 电化学检测法测量氧化 DNA 损伤，用体外测定法评估 BER 活性，该方法采用带有 8-OHdG 损伤的底物质粒 DNA，并用免疫印迹法测定 OGG1 蛋白水平。处理后 2 小时，与对照组相比，AFB1 使小鼠肺 DNA 中的 8-OHdG 水平增加了约 69%（p<0.05），但不改变肝中的 8-OHdG 水平或肺或肝中的 5-OHdC 水平（p>0.05）。AFB1 处理还使小鼠肺中的 BER 活性增加了约 87%（p<0.05），但不影响肝中的 BER 活性（p>0.05）。肺（20%）和肝（60%）中的 OGG1 免疫反应性蛋白水平增加（p<0.05）。这些结果与氧化 DNA 损伤有助于该模型中 AFB1 的致癌性一致。
