Proulx Léa-Isabelle, Castonguay André, Bissonnette Elyse Y
Centre de Recherche, Hôpital Laval, Institut Universitaire de Cardiologie et de Pneumologie de l'Université Laval, Canada.
Carcinogenesis. 2004 Jun;25(6):997-1003. doi: 10.1093/carcin/bgh103. Epub 2004 Feb 4.
NNK, a nicotine-derived nitrosamine, is a potent lung carcinogen that generates electrophilic intermediates capable of damaging DNA. The effects of NNK on the immune response, which may facilitate lung carcinogenesis, are poorly understood. Alveolar macrophages (AM), a key cell in the maintenance of lung homeostasis, metabolize NNK via two major metabolic activation pathways: alpha-methylhydroxylation and alpha-methylenehydroxylation. We have shown previously that NNK inhibits the production of interleukin-12 (IL-12) and tumor necrosis factor (TNF), but stimulates the production of IL-10 and prostaglandin E(2) (PGE(2)) by AM. In the present study, we investigated the contribution of each activation pathway in the modulation of AM function. We used two precursors, 4-[(acetoxymethyl)-nitrosamino]-1-(3-pyridyl)-1-butanone (NNKOAc) and N-nitro(acetoxymethyl)methylamine (NDMAOAc), which generate the reactive electrophilic intermediates [4-(3-pyridyl)-4-oxo-butanediazohydroxide and methanediazohydroxide, respectively] in high yield and exclusively. Rat AM cell line, NR8383, was stimulated and treated with different concentrations of NNKOAc or NDMAOAc (12, 25 and 50 microM). Mediator release was measured in cell-free supernatants. NNKOAc significantly inhibited the production of IL-10, IL-12, TNF and nitric oxide but increased the release of PGE(2) and cyclooxygenase-2 expression suggesting that the alpha-methylhydroxylation pathway might be responsible for NNK modulation of AM cytokine release. In contrast, NDMAOAc did not modulate AM mediator production. However, none of these precursors, alone or in combination, could explain the stimulation of AM IL-10 production by NNK. Our results suggest that the alpha-methylhydroxylation of NNK leading to DNA pyridyloxobutylation also modulates cytokine production in NNK-treated AM.
NNK是一种源自尼古丁的亚硝胺，是一种强效的肺癌致癌物，可产生能够损伤DNA的亲电中间体。人们对NNK对免疫反应的影响了解甚少，而这种影响可能会促进肺癌的发生。肺泡巨噬细胞（AM）是维持肺稳态的关键细胞，它通过两种主要的代谢激活途径代谢NNK：α-甲基羟基化和α-亚甲基羟基化。我们之前已经表明，NNK会抑制白细胞介素-12（IL-12）和肿瘤坏死因子（TNF）的产生，但会刺激AM产生IL-10和前列腺素E2（PGE2）。在本研究中，我们研究了每种激活途径在调节AM功能中的作用。我们使用了两种前体，4-[(乙酰氧基甲基)-亚硝氨基]-1-(3-吡啶基)-1-丁酮（NNKOAc）和N-硝基(乙酰氧基甲基)甲胺（NDMAOAc），它们能分别高产且专一性地产生反应性亲电中间体[4-(3-吡啶基)-4-氧代-丁二氮杂氢氧化物和甲二氮杂氢氧化物]。用不同浓度（12、25和50微摩尔）的NNKOAc或NDMAOAc刺激并处理大鼠AM细胞系NR8383。在无细胞上清液中测量介质释放。NNKOAc显著抑制IL-10、IL-12、TNF和一氧化氮的产生，但增加了PGE2的释放和环氧合酶-2的表达，这表明α-甲基羟基化途径可能负责NNK对AM细胞因子释放的调节。相比之下，NDMAOAc没有调节AM介质的产生。然而，这些前体单独或联合使用都无法解释NNK对AM产生IL-10的刺激作用。我们的结果表明，NNK的α-甲基羟基化导致DNA吡啶氧基丁基化，也调节了NNK处理的AM中的细胞因子产生。
