Nicotinic receptors mediate tumorigenic action of tobacco-derived nitrosamines on immortalized oral epithelial cells
Nicotinic receptors mediate tumorigenic action of tobacco-derived nitrosamines on immortalized oral epithelial cells
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DOI：
10.4161/cbt.5.5.2601
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发表时间：
2006-05-01
影响因子：
3.6
通讯作者：
Grando, Sergei A.
中科院分区：
文献类型：
--
作者：
Arredondo, Juan;Chernyavsky, Alex I.;Grando, Sergei A.
经常使用无烟烟草（ST）的人患口腔癌的风险增加。尼古丁及其衍生物可能通过刺激靶细胞中的尼古丁乙酰胆碱受体（nAChRs）而促进肿瘤的发生。新发现的证据表明，nachr可被尼古丁衍生的亚硝胺4-（甲基亚硝胺）1-（3-吡啶基）- 1-丁酮（NNK）和N'-亚硝基尼古丁（NNN）刺激，在实验动物中诱发口腔肿瘤。本研究旨在阐明受体介导的NNK-和nnn诱导口腔癌的发生和发展机制。我们使用了能够表达α 3、α 5、α 7、α 9、β 2和β 4 nAChR亚基的Het-1A细胞。NNK和NNN都与烟碱放射性配体竞争与ht - 1a细胞结合。NNK对[(3)H]尼古丁标记的结合位点的亲和力高于NNN，而NNN-对[(3)H]表贝替丁敏感的nachr的亲和力高于NNN。NNK和NNN均能增加Het-1A细胞的增殖潜能，并产生抗凋亡作用，但拮抗剂可减轻这种作用。甲虫毒素对NNK最有效，甲胺胺对NNN最有效。用NNK或NNN处理Het-1A细胞，在裸鼠中获得了锚定独立生长的能力和产生肿瘤的能力，这两种能力都可以被拮抗剂抑制。为了阐明信号机制，我们研究了编码细胞周期、凋亡和信号转导调节因子的基因在mRNA和蛋白水平上的转录。亚硝胺刺激的ht - 1a细胞显示编码PCNA和Bcl-2的mRNA转录物数倍增加，转录因子GATA-3、核因子κ B和STAT-1的表达上调。NNK和NNN诱导的STAT-1蛋白结合活性与基因表达升高相关。这些结果确立了特定nAChR亚型在烟草相关癌变中的作用，为口腔癌的化学预防开辟了新的途径。
Frequent users of smokeless tobacco (ST) have an increased risk for developing oral cancer. Nicotine and its derivatives may contribute to tumorigenesis through stimulation of nicotinic acetylcholine receptors (nAChRs) in target cells. Emerging evidence indicates that nAChRs can be stimulated by the nicotine-derived nitrosamines 4-(methylnitrosamino)1-(3-pyridyl)- 1- butanone (NNK) and N'-nitrosonornicotine (NNN) that can induce oral cavity tumors in laboratory animals. This study was designed to elucidate the receptor-mediated mechanisms of the initiation and progression of NNK-, and NNN-induced oral cancers. We used Het-1A cells that were found to express alpha 3, alpha 5, alpha 7, alpha 9, beta 2 and beta 4 nAChR subunits. Both NNK and NNN competed with nicotinic radioligands for binding to Het-1A cells. NNK showed a higher than NNN affinity to the [(3)H] nicotine-labeled binding sites, and NNN- to the [(3)H] epibatidine-sensitive nAChRs. NNK and NNN increased proliferative potential of Het-1A cells and produced an anti-apoptotic effect, which was alleviated by antagonists. alpha-Bungarotoxin was most effective against NNK and mecamylamine against NNN. Treatment of Het-1A cells with either NNK or NNN led to acquisition of capability of anchorage independent growth and ability to produce tumors in nude mice, both of which can be by inhibited by antagonists. To elucidate the signaling mechanisms, we studied transcription of the genes encoding the cell cycle, apoptosis and signal transduction regulators at both the mRNA and protein levels. The Het-1A cells stimulated with nitrosamines showed multifold increases of the mRNA transcripts encoding PCNA and Bcl-2, and upregulated expression of the transcription factors GATA-3, nuclear factor-kappa B, and STAT-1. The STAT-1 protein-binding activity induced by NNK and NNN correlated with elevated gene expression. The obtained results establish the role of specific nAChR subtypes in tobacco-related carcinogenesis and open a novel avenue for oral cancer chemoprevention.