A receptor-mediated mechanism of nicotine toxicity in oral keratinocytes
A receptor-mediated mechanism of nicotine toxicity in oral keratinocytes
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DOI：
10.1038/labinvest.3780379
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发表时间：
2001-12-01
影响因子：
5
通讯作者：
Grando, SA
中科院分区：
文献类型：
--
作者：
Arredondo, J;Nguyen, VT;Grando, SA
吸烟和无烟烟草引起的发病率源于皮肤和上消化道的上皮衬里。口腔角质形成细胞(OKC)表达与尼古丁(NIC)结合的烟碱型乙酰胆碱受体(NAChRs)。我们研究了烟草产品对OKC的受体介导的毒性机制。正常人OKC与NIC预先孵育后，其nAChRs的配体结合动力学改变，提示nAChRs发生了结构变化。OKC暴露于NIC会导致转录和翻译的改变，这一发现证实了这一假设。通过RT-PCR和免疫印迹，我们发现α3、α5、α7、β2和β4nAChR亚基的mRNA和蛋白水平增加了1.5到2.9倍。NIC还改变了细胞周期和细胞分化标志物Ki-67、增殖细胞核抗原、p21、细胞周期蛋白D1、p53、微丝蛋白、氯化蛋白和细胞角蛋白1和10的mRNA和蛋白水平。烟碱拮抗剂Mecamylamine阻止了这些变化，这表明NIC诱导的nAChR和细胞周期和细胞分化基因表达的变化是由NIC对nAChRs的药物刺激所致。为了确定这些发现与烟草制品在体内的病理生物学效应的相关性，我们研究了大鼠和小鼠暴露于环境香烟烟雾或含有等量NIC的饮用水后3周口腔组织中的上述参数，这些参数与病理生理相关。NAChRs、细胞周期和细胞分化基因的变化与体外发现的相似。组织标本的间接免疫荧光分析结果证实了这些发现。因此，烟草制品在口腔组织中的某些病理生物学效应可能源于NIC诱导的角质形成细胞nAChRs结构和功能的改变，角质形成细胞nAChRs负责细胞递质乙酰胆碱对细胞周期的生理调节。
Smoking and smokeless tobacco cause morbidity that originates from the epithelium lining of the skin and upper digestive tract. Oral keratinocytes (OKC) express nicotinic acetylcholine receptors (nAChRs) that bind nicotine (Nic). We studied the mechanism of the receptor-mediated toxicity of tobacco products on OKC. Preincubation of normal human OKC with Nic altered the ligand-binding kinetics of their nAChRs, suggesting that the nAChRs underwent structural changes. This hypothesis was confirmed by the finding that exposure of OKC to Nic causes transcriptional and translational changes. Through RT-PCR and immunoblotting, we found a 1.5- to 2.9-fold increase in the mRNA and protein levels of alpha3, alpha5, alpha7, beta2, and beta4 nAChR subunits. Exposure of OKC to Nic also changed the mRNA and protein levels of the cell cycle and cell differentiation markers Ki-67, PCNA, p21, cyclin D1, p53, filaggrin, loricrin, and cytokeratins 1 and 10. The nicotinic antagonist mecamylamine prevented these changes, which indicates that the Nic-induced changes in the expression of both the nAChR and the cell cycle and cell differentiation genes resulted from pharmacologic stimulation of nAChRs with Nic. To establish the relevance of these findings to the pathobiologic effects of tobacco products in vivo, we studied the above parameters in the oral tissue of rats and mice after their exposure for 3 weeks to environmental cigarette smoke or drinking water containing equivalent concentrations of Nic that are pathophysiologically relevant. The changes of the nAChRs and the cell cycle and cell differentiation genes were similar to those found in vitro. The results of indirect immunofluorescence assay of tissue specimens validated these findings. Thus, some pathobiologic effects of tobacco products in oral tissues may stem from Nic-induced alterations of the structure and function of keratinocyte nAChRs responsible for the physiologic regulation of the cell cycle by the cytotransmitter acetylcholine.