Tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces cell proliferation in normal human bronchial epithelial cells through NFkappaB activation and cyclin D1 up-regulation.
Cigarette smoke contains several carcinogens known to initiate and promote tumorigenesis as well as metastasis. Nicotine is one of the major components of the cigarette smoke and the 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a tobacco-specific carcinogen. Here, we demonstrated that NNK stimulated cell proliferation in normal human bronchial epithelial cells (NHBE) and small airway epithelial cells (SAEC). Cells exposed to NNK resulted in an increase in the level of cyclin D1 protein (as early as 3-6 h). Increased phosphorylation of the Rb Ser(795) was detected at 6-15 h after NNK treatment and thereby promoted cells entering into the S phase (at 15-21 h). The increased cyclin D1 protein level was induced through activation of the transcription factor, nuclear factor kB (NFkappaB), in the NHBE cells. Treatment of the NHBE cells with PD98059, an ERK1/2 (extracellular signal-regulated protein kinase)-specific inhibitor, specifically suppressed the NNK-induced IkappaBalpha phosphorylation at position 32 of the serine residue, suggesting that the ERK1/2 kinase was involved in the IkappaBalpha phosphorylation induced by NFkappaB activation. To determine whether the NNK-induced NFkappaB activation and cyclin D1 induction were also observed in vivo, A/J mice were treated with NNK (9.1 mg) for 20 weeks and the results showed a significant induction of cyclin D1 and NFkappaB translocation determined by immunoblotting analyses. We further demonstrated that the nicotine acetylcholine receptor (nAchR), which contains the alpha3-subunit, was the major target mediating NNK-induced cyclin D1 expression in the NHBE cells. In summary, our findings demonstrate for the first time that NNK could stimulate normal human bronchial cell proliferation through activation of the NFkappaB, which in turn up-regulated the cyclin D1 expression.
Ho
Yuan-Soon
YS
Graduate Institute of Biomedical Technology, Taipei Medical University, Taipei, Taiwan.
Chen
Chien-Ho
CH
Wang
Ying-Jan
YJ
Pestell
Richard G
RG
Albanese
Chris
C
Chen
Rong-Jane
RJ
Chang
Mei-Chi
MC
Jeng
Jiiang-Huei
JH
Lin
Shyr-Yi
SY
Liang
Yu-Chih
YC
Tseng
How
H
Lee
Wen-Sen
WS
Lin
Jen-Kun
JK
Chu
Jan-Show
JS
Chen
Li-Ching
LC
Lee
Chia-Hwa
CH
Tso
Wei-Ling
WL
Lai
Yann-Chwen
YC
Wu
Chih-Hsiung
CH
D001980:Bronchi / Q000166:cytology*; D002273:Carcinogens / Q000633:toxicity*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D019938:Cyclin D1 / Q000819:agonists* / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D016328:NF-kappa B / Q000819:agonists* / Q000096:biosynthesis; D009602:Nitrosamines / Q000633:toxicity*; D010766:Phosphorylation; D011978:Receptors, Nicotinic / Q000502:physiology; D016160:Retinoblastoma Protein / Q000378:metabolism; D015854:Up-Regulation
D002273:Carcinogens; D019938:Cyclin D1; D048052:Mitogen-Activated Protein Kinase 3; D016328:NF-kappa B; D009602:Nitrosamines; D011978:Receptors, Nicotinic; D016160:Retinoblastoma Protein; C016583:4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone