title: Denatonium inhibits growth and induces apoptosis of airway epithelial cells through mitochondrial signaling pathways.
abstract: BACKGROUND
  Denatonium, a widely used bitter agonist, activates bitter taste receptors on many cell types and plays important roles in chemical release, ciliary beating and smooth muscle relaxation through intracellular Ca(2+)-dependent pathways. However, the effects of denatonium on the proliferation of airway epithelial cells and on the integrity of cellular components such as mitochondria have not been studied. In this study, we hypothesize that denatonium might induce airway epithelial cell injury by damaging mitochondria.
  
  
  METHODS
  Bright-field microscopy, cell counting kit-8 (CCK-8) assay and flow cytometry analysis were used to examine cellular morphology, proliferation and cell cycle, respectively. Transmission electron microscopy (TEM) was used to examine mitochondrial integrity. JC-1 dye and western blotting techniques were used to measure mitochondrial membrane potential and protein expression, respectively.
  
  
  RESULTS
  For airway epithelial cells, we observed that denatonium significantly effects cellular morphology, decreases cell proliferation and reduces the number of cells in S phase in a dose-dependent manner. TEM analysis demonstrated that denatonium causes large amplitude swelling of mitochondria, which was confirmed by the loss of mitochondrial membrane potential, the down-regulation of Bcl-2 protein and the subsequent enhancement of the mitochondrial release of cytochrome c and Smac/DIABLO after denatonium treatment.
  
  
  CONCLUSIONS
  In this study, we demonstrated for the first time that denatonium damages mitochondria and thus induces apoptosis in airway epithelial cells.
authors: Department of Pulmonary Medicine, Research Institute of Respiratory Disease, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Shanghai, 200032, China. wenxiaoxing666@163.com.
authors: Xiaoxing
authors: X
authors: Wen
authors: Department of Pulmonary Medicine, Research Institute of Respiratory Disease, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Shanghai, 200032, China. zhou.jian@fudan.edu.cn.
authors: Jian
authors: J
authors: Zhou
authors: Department of Pulmonary Medicine, Research Institute of Respiratory Disease, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Shanghai, 200032, China. zhangdan6250@yeah.net.
authors: Dan
authors: D
authors: Zhang
authors: Department of Pulmonary Medicine, Research Institute of Respiratory Disease, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Shanghai, 200032, China. liumiao.lijing@163.com.
authors: Jing
authors: J
authors: Li
authors: Department of Pulmonary Medicine, Research Institute of Respiratory Disease, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Shanghai, 200032, China. wangqin19851125@126.com.
authors: Qin
authors: Q
authors: Wang
authors: Department of Pulmonary Medicine, Research Institute of Respiratory Disease, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Shanghai, 200032, China. fnn2005508@126.com.
authors: Nana
authors: N
authors: Feng
authors: Department of Pulmonary Medicine, Research Institute of Respiratory Disease, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Shanghai, 200032, China. starfishzhu@gmail.com.
authors: Haixing
authors: H
authors: Zhu
authors: Department of Pulmonary Medicine, Research Institute of Respiratory Disease, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Shanghai, 200032, China. song.yuanlin@zs-hospital.sh.cn.
authors: Yuanlin
authors: Y
authors: Song
authors: Department of Pulmonary Medicine, Research Institute of Respiratory Disease, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Shanghai, 200032, China. li.huayin@zs-hospital.sh.cn.
authors: Huayin
authors: H
authors: Li
authors: Department of Pulmonary Medicine, Research Institute of Respiratory Disease, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Shanghai, 200032, China. bai.chunxue@zs-hospital.sh.cn.
authors: Chunxue
authors: C
authors: Bai
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D008168:Lung / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D008933:Mitochondrial Swelling / Q000187:drug effects; D000644:Quaternary Ammonium Compounds / Q000633:toxicity*; D043562:Receptors, G-Protein-Coupled / Q000187:drug effects / Q000378:metabolism; D059807:S Phase Cell Cycle Checkpoints / Q000187:drug effects*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D051017:Apoptosis Regulatory Proteins; D000644:Quaternary Ammonium Compounds; D043562:Receptors, G-Protein-Coupled; C043414:denatonium
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