Enhancement of benzo[a]pyrene diol epoxide mutagenicity by sulfite in a mammalian test system.
Enhancement of benzo[a]pyrene diol epoxide mutagenicity by sulfite in a mammalian test system.
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在哺乳动物测试系统中亚硫酸盐增强苯并[a]芘二醇环氧化物致突变性。
DOI：
10.1093/carcin/17.5.1063
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发表时间：
1996
期刊：
影响因子：
4.7
通讯作者：
Jones,BC
中科院分区：
文献类型：
--
作者：
Reed,GA;Jones,BC
二氧化硫是一种普遍存在的空气污染物，是苯并[a]芘（BP）的共同致癌物。我们之前已经证明，亚硫酸盐（二氧化硫的生理形态）与BP的最终致癌形态（±）-7r， 8t-二羟基-9t， 10t-环氧- 7,8,9,10 -四氢苯并[a]芘（抗bpde）之间的相互作用会增强鼠伤寒沙门氏菌TA98和TA100的致突变作用。我们在这里报道，亚硫酸盐的这种相同的共诱变效应发生在哺乳动物细胞系。用50nanti - bpde（剂量反应线性部分的浓度）处理中国仓鼠V79细胞，导致基因座突变相对于自发率增加4倍。当V79细胞在加入抗bpde之前立即暴露于1或10 mM亚硫酸盐中时，突变率分别比单独使用抗bpde引起的突变率增加了73%和210%。亚硫酸盐本身具有中等细胞毒性，但没有引起超过自发率的突变率增加。亚硫酸盐增强环氧二醇致突变性的剂量和时间依赖性的表征与以前在细菌系统中看到的效果非常相似。特别是，当亚硫酸盐在加入环氧二醇前60分钟至1分钟加入细胞时，亚硫酸盐的增强效果明显。同时加入亚硫酸盐和环氧二醇会减弱强化效果，在环氧二醇加入10 min后再加入亚硫酸盐，强化效果完全消失。亚硫酸盐与浓度为1或10 mM的硫酸盐相比，表现出适度的细胞毒性，但既不直接致突变，也不能增强抗bpde的致突变作用。与标记抗bpde的结合研究表明，添加10 mM亚硫酸盐使抗bpde与DNA的结合增加了43%以上，与观察到的突变频率增加相对应。有趣的是，这种DNA修饰水平的差异在暴露30分钟至2小时后并不明显，而仅在4小时时出现。4h点被常规用于所有的诱变性研究。抗bpde衍生材料与细胞RNA的结合未被10mm亚硫酸盐改变。在最近的时间点出现的DNA修饰增加表明，与环氧二醇相比，活性DNA结合的时间更长，或者识别和清除特定DNA加合物的能力有所不同。讨论了这两种可能性关于在这些培养中观察到的7r，8t，9t-三羟基-7,8,9,10-四氢苯并[a]芘- c-磺酸盐（bpt -10-磺酸盐）的形成。bpt -10-磺酸盐是一种相对稳定的BP衍生物，保留了共价修饰DNA的能力。这些数据有力地说明了该衍生物在亚硫酸盐增强环氧二醇致突变性中的作用。
Sulfur dioxide, a ubiquitous air pollutant, is a co-carcinogen for benzo[a]pyrene (BP). We have demonstrated previously that the interaction between sulfite, the physiological form of sulfur dioxide, and (±)-7r, 8t-dihydroxy-9t, 10t-epoxy-7, 8, 9, 10-tetrahydrobenzo[a]pyrene (anti-BPDE), the ultimate carcinogenic form of BP, results in an enhanced mutagenic effect inSalmonella typhimuriumstrains TA98 and TA100. We report here that this same co-mutagenic effect of sulfite occurs in a mammalian cell line. Treatment of Chinese hamster V79 cells with 50 nManti-BPDE, a concentration on the linear portion of the dose-response, resulted in a four-fold increase in mutations at thehprtlocus relative to the spontaneous rate. When V79 cells were exposed to 1 or 10 mM sulfite immediately prior to the addition ofanti-BPDE, the mutation rate increased by 73% and 210%, respectively, over that elicited byanti-BPDE alone. Sulfite itself was moderately cytotoxic, but caused no increase in mutation over the spontaneous rate. Characterization of the dose- and time-dependance of this enhancement of diol epoxide mutagenicity by sulfite closely resembled the effects seen previously in the bacterial system. In particular, enhancement by sulfite was evident when sulfite was added to the cells between 60 min and 1 min prior to the addition of the diol epoxide. Concurrent addition of sulfite and the diol epoxide attenuated the enhancement, and the effect was lost altogether when sulfite was added 10 min after the diol epoxide. The specificity of this effect of sulfite was shown by comparison with sulfate, which at concentrations of either 1 or 10 mM exhibited modest cytotoxicity, but neither was directly mutagenic nor able to enhance the mutagenic effect ofanti-BPDE. Binding studies with labeledanti-BPDE showed that the addition of 10 mM sulfite increased binding ofanti-BPDE to DNA by over 43%, corresponding to the observed increase in mutant frequency. Interestingly, this difference in level of DNA modification was not apparent after 30 min to 2 h exposures, but only emerged at the 4 h time point. The 4 h point was routinely used for all mutagenicity studies. Binding ofanti-BPDE-derived materials to cellular RNA was not altered by 10 mM sulfite. The emergence of increased DNA modification at the latest time point suggests either a more prolonged period of active DNA binding than would occur with diol epoxide, or a difference in the ability to recognize and clear specific DNA adducts. Both possibilities are discussed in regard to the observed formation of 7r,8t,9t-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene- lOc-sulfonate (BPT-10-sulfonate) in those incubations. BPT-10-sulfonate is a relatively stable BP derivative which retains the ability to covalently modify DNA. The role of this derivative in the enhancement of diol epoxide mutagenicity by sulfite is strongly suggested by these data.