TRANSPORT OF DNA-ADDUCTING METABOLITES IN MOUSE SERUM FOLLOWING BENZO[A]PYRENE ADMINISTRATION
TRANSPORT OF DNA-ADDUCTING METABOLITES IN MOUSE SERUM FOLLOWING BENZO[A]PYRENE ADMINISTRATION
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DOI：
10.1093/carcin/10.4.673
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发表时间：
1989-04-01
期刊：
影响因子：
4.7
通讯作者：
ATHERHOLT, TB
中科院分区：
文献类型：
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作者：
GINSBERG, GL;ATHERHOLT, TB
细胞酶对苯并[a]芘（BaP）的代谢激活是DNA加合物形成所必需的。体内DNA加合物也可能来自通过体循环供应的BaP代谢物，而不是来自原位激活。我们通过用鲑鱼精子DNA （ssDNA）捕获代谢物，然后对DNA加合物进行32p标记后分析，确定在BaP给药后4小时（i.p.）小鼠血清中是否可以检测到亲电代谢物。体外研究表明，小鼠血清可隔离bap -7,8-二醇-9,10-环氧化物（BPDE）并保护其不被水解。BPDE迅速从血清转移到ssDNA或脾细胞，ssDNA中的加合物水平比脾细胞高4- 7倍。经BaP处理后，小鼠血清与ssDNA孵育产生两个加合点。主要加合物（斑点3）与BPDE加合物标准共色谱，而次要加合物（斑点2）与BPDE无关。建立对照血清BPDE标准曲线，定量测定给药血清BPDE水平。这些水平范围为13.1至19.1 nM。组织DNA包含三个加合物点：点2和3看起来与分别从剂量血清中产生的加合物相同。组织中BPDE-DNA加合物在肝脏、肺和脾脏中含量最高，肾脏和胃中含量显著降低。加合物2的水平与加合物3的水平没有相关性，特别是在脾脏中，加合物2/加合物3的比例非常低。在体外研究中，两种加合代谢物均存在于脾细胞中，表明脾细胞优先形成加合物3。这些结果表明，在小鼠血清中存在导致细胞DNA损伤的三种BaP亲电代谢物中的两种。血清中BPDE的水平可能足以说明BPDE- dna加合物的组织负荷的很大一部分。
Metabolic activation of benzo[a]pyrene (BaP) by cellular enzymes is required for DNA adduct formation. In vivo DNA adducts might also arise from BaP metabolites supplied via the systemic circulation, rather than from in situ activation. We determined whether electrophilic metabolites could be detected in mouse serum 4 h after BaP dosing (i.p.) by trapping metabolites with salmon sperm DNA (ssDNA), followed by 32P-postlabeling analysis for DNA adducts. In vitro studies demonstrated that mouse serum sequesters BaP-7,8-diol-9,10-epoxide (BPDE) and protects it from hydrolysis. BPDE was rapidly transferred from serum to ssDNA or splenocytes, with adduct levels in ssDNA 4- to 7-fold greater than in splenocytes. After BaP administration, mouse serum produced two adduct spots when incubated with ssDNA. The major adduct (spot 3) co-chromatographed with a BPDE adduct standard, while the minor adduct (spot 2) was unrelated to BPDE. A BPDE standard curve in control serum was developed to quantitate BPDE levels in dosed serum. These levels ranged from 13.1 to 19.1 nM. Tissue DNA contained three adduct spots: spots 2 and 3 appeared identical to the respective adducts arising from dosed serum. BPDE-DNA adducts in tissues were highest in liver, lung and spleen, with kidney and stomach levels significantly lower. Levels of adduct 2 did not correlate with levels of adduct 3, especially in spleen where the adduct 2/adduct 3 ratio was very low. In vitro studies in which splenocytes were presented with both adducting metabolites suggest that splenocytes preferentially form adduct 3. These results indicate that two of the three BaP electrophilic metabolites responsible for cellular DNA damage are present in mouse serum. The levels of BPDE in serum may be sufficient to account for a substantial portion of the tissue load of BPDE-DNA adducts.