Investigation of the role of lipoxygenase in bioactivation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in human lung.
Investigation of the role of lipoxygenase in bioactivation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in human lung.
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DOI：
10.1021/tx025524m
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发表时间：
2002-09
影响因子：
4.1
通讯作者：
L. Bedard;Graeme B. J. Smith;K. Reid;D. Petsikas;T. Massey
中科院分区：
文献类型：
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作者：
L. Bedard;Graeme B. J. Smith;K. Reid;D. Petsikas;T. Massey
4-甲基亚硝基氨基-1-（3-吡啶基）-1-丁酮（NNK）是一种强效的烟草特异性致癌物，据信在人类肺癌中发挥作用。NNK的生物活化涉及可由细胞色素P450、血红蛋白和脂氧合酶（LOX）催化的α-碳羟基化。在本研究中，LOX在NNK生物活化中的作用进行了研究。在与4.2 μ M [5-（3）H]NNK（N = 6）孵育的人肺细胞溶胶中观察到酮酸（α-亚甲基NNK羟基化的终点代谢产物）的形成。在伴刀豆球蛋白A亲和层析富集人肺脂氧合酶（HLLO）后，含有细胞溶质组分较少LOX的级分（级分1）保留了生物活化NNK的能力。尽管富集的HLLO表现出特征性的双加氧酶和氢过氧化物酶活性，但它不生物活化NNK。LOX抑制剂去甲二氢愈创木酸抑制HLLO的双加氧酶活性达83 +/- 19%（P 0.05）。大豆LOX催化NNK生物活化的失败支持了在人肺细胞溶胶中观察到的结果，并且化学产生的烷基过氧自由基生物活化NNK的失败进一步表明LOX的双加氧酶活性不太可能参与NNK生物活化。辣根过氧化物酶和髓过氧化物酶催化的NNK生物活化也检测不到。我们的研究结果表明，虽然人肺细胞质溶胶可以生物激活NNK形成酮酸，LOX不参与。我们已经将粗制人肺细胞质溶胶生物活化NNK的能力归因于血红蛋白。1-氨基苯并三唑和花生四烯酸分别对粗细胞溶胶和级分1中酮酸形成的抑制作用（P < 0.05，N = 6）与血红蛋白催化的NNK生物活化一致。
4-Methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK) is a potent tobacco-specific carcinogen believed to play a role in human lung cancer. Bioactivation of NNK involves alpha-carbon hydroxylation that could be catalyzed by cytochrome P450, hemoglobin, and lipoxygenases (LOX). In the present study, the role of LOX in NNK bioactivation was investigated. Formation of keto acid, the endpoint metabolite of alpha-methylene NNK hydroxylation, was observed in human lung cytosols incubated with 4.2 microM [5-(3)H]NNK (N = 6). Following concanavalin A affinity chromatography to enrich human lung lipoxygenase (HLLO), the fraction containing cytosolic components less LOX (fraction 1) retained the ability to bioactivate NNK. Although enriched HLLO exhibited the characteristic dioxygenase and hydroperoxidase activities, it did not bioactivate NNK. The LOX inhibitor nordihydroguaiaretic acid inhibited dioxygenase activity of HLLO by 83 +/- 19% (P 0.05). Failure of soybean LOX to catalyze NNK bioactivation supported the results observed in human lung cytosols, and failure of chemically generated alkylperoxyl radicals to bioactivate NNK further suggested that the dioxygenase activity of LOX is not likely to be involved in NNK bioactivation. Horseradish peroxidase and myeloperoxidase catalyzed NNK bioactivation were also nondetectable. Our results demonstrate that, although human lung cytosols can bioactivate NNK to form keto acid, LOX is not involved. We have attributed the ability of crude human lung cytosols to bioactivate NNK to hemoglobin. The inhibitory effect of 1-aminobenzotriazole and arachidonic acid on keto acid formation in the crude cytosols and in fraction 1, respectively (P < 0.05, N = 6), is consistent with hemoglobin-catalyzed NNK bioactivation.