ORIGINAL ARTICLE The alpha9 Nicotinic Acetylcholine Receptor is the Key Mediator in Nicotine-enhanced Cancer Metastasis in Breast Cancer Cells Chin-Sheng Hung 1 , 2, 4 , Yu-Jin Peng 2 , Po-Li Wei 1 , 2, 3, 4, 5 , Chia-Hwa Lee 6 , Hou-Yu Su 9 , Yuan-Soon Ho 5, 6, 7 , Shyr-Yi Lin 10, 11 , Chih-Hsiung Wu 1 , 2, 4, 8 , Yu-Jia Chang 1 , 2, 3, 4, 5 * 1 Graduate Institute of Clinical Medicine, Taipei Medical University, Taipei, Taiwan 2 Division of General Surgery, Department of Surgery, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan 3 Cancer Center, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan 4 Department of Surgery, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan 5 Center of Excellence for Cancer Research, Taipei Medical University, Taipei, Taiwan 6 School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan 7 Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan 8 Department of Surgery, Taipei Medical University-Shuang Ho Hospital, Taipei, Taiwan 9 Department of Surgery, Saint Mary’s Hospital Luodong, Yilan County, Taiwan 10 Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan 11 Cancer Center, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan article info Article history: Received: Aug 22, 2011 Revised: Oct 6, 2011 Accepted: Oct 14, 2011 KEY WORDS: breast cancer; epithelial-to-mesenchymal transition (EMT); migration; nicotine; nicotinic acetylcholine receptor (nAChR); smoking Background/purpose: The tobacco-specific mitogen nicotine was reported to correlate with cancer progression and tumorigenesis in breast cancer. Metastasis is a majorcause of cancer death, so the influ- ence of nicotine on breast cancer cell migration is also of interest. Our aim is to elucidate the mechanisms of nicotine-enhanced migration of breast cancer cells and thereby achieve better control of metastasis. Methods: The influence of nicotine on breast cancer cell migration was evaluated by trans-well and wound-healing migration assays. Receptor-mediated migration was studied with both a small molecule inhibitor and small interfering RNA (siRNA). Results: The alpha9 nicotinic acetylcholine receptor, a9nAChR, was identified in breast cancer cell lines MCF-7 and MDA-MB-231. Nicotine enhanced cell migration in both trans-well and wound-healing migration assays. We used a specific inhibitor and siRNA to demonstrate that a9nAChR is the key modulator in medi- ating nicotine-enhanced breast cancer cell migration through up-regulation of fibronectin and vimentin. Conclusion: Nicotine treatment enhanced breast cancer metastasis through a9nAChR signaling via enhanced fibronectin and vimentin expression. Copyright Ó 2011, Taipei Medical University. Published by Elsevier Taiwan LLC. All rights reserved. 1. Introduction Breast cancer is an important health issue worldwide. It is the most common malignancy in women. 1 Approximately 207,090 women were diagnosed with breast cancer in 2010 in the United States alone, representing approximately 28% of all female malignancies. 2 This number is 2-fold higher than the second-ranked malignancy in women, lung cancer (14%). 2 In Taiwan, breast cancer is character- ized by increasing incidence and the fact that patients are of rela- tively young or median age (4549 years) at diagnosis. 3 Most of the patients were diagnosed with early-stage breast cancer, which can be treated with combinations of surgery, chemotherapy and radiotherapy. However, approximately 30% of early breast cancer patients progress to develop metastatic breast cancer in the following years. With late-stage metastatic breast cancer, patients have a limited choice of further therapies and greatly diminished chances of cure. 4e6 Thus, the identification of factors that predis- pose to cancer metastasis will be helpful in reducing metastasis and improving the survival rate. Tobacco smoke contains over 4000 chemical compounds, many of which are carcinogenic or mutagenic. 7e9 Nicotine is major component that is present in tobacco. It functions on the central nervous system and is responsible for addiction to tobacco. 10,11 Many studies have shown that nicotine may also enhance the progression of several different cancers, including lung, colon, gastric and breast cancers. 12e21 In general, nicotine interacts with nicotinic acetyl- choline receptors (nAChRs) to activate downstream signaling path- ways that promote cancer progression and metastasis. 22e25 Structurally, nAchRs are pentamers composed of combinations of 17 subunits (a1e 10, b1eb4, 3and d). 26 The majority of nAchRs are heteropentamers, and only subunits a7 to a10 can form * Corresponding author. 250 Wu-Xin Street, Taipei City, Taiwan 110, Taiwan. E-mail: Y.-J. Chang <r5424012@tmu.edu.tw> Contents lists available at SciVerse ScienceDirect Journal of Experimental and Clinical Medicine journal homepage: http://www.jecm-online.com 1878-3317/$ e see front matter Copyright Ó 2011, Taipei Medical University. Published by Elsevier Taiwan LLC. All rights reserved. doi:10.1016/j.jecm.2011.10.008 J Exp Clin Med 2011;3(6):283e292