The effects of nicotine in non small cell lung cancers by binding neuronal nicotinic acetylcholine receptors

Introduction Lung cancer is the leading cause of cancer death worldwide and smoking accounts for approximately 70% of non-small cell lung cancer (NSCLC) and 90% of small cell lung cancer (SCLC) cases, although there is a subset of patients who develop lung cancer without a history of smoking. Tobacco smoke contains multiple classes of carcinogens, and nicotine, the most active component of tobacco smoke, by binding to cell-surface neuronal nicotinic acetylcholine receptors (nAChRs), promotes tumour growth and metastasis by inducing cell-cycle progression, migration and invasion. In this work we have analysed the nAChR expression in lung cancer cell lines and lung cancer tissues. We have investigated the effects of nicotine in regulating cell proliferation and cell migration and studied the intracellular signalling of nicotine. Material and method We used two human NSCLC cell lines (A549 and H-1975) and lung cancer tissues obtained from patients. Analysis of mRNAs subunit expression was evaluated by qRT-PCR in both NSCLC cell lines and tissues. Cell viability assay (MTS) and cell counting experiments have been performed in cells quiescent by serum starvation for 48 hours and stimulated with nicotine or nAChR antagonists. After the pharmacological treatments the cells were lysed and used for immunoblot analyses to detect phospho-ERK and phospho-AKT levels. Boyden Chamber assay and wound healing assay measure A549 invasion property. Result and discussion qRT-PCR shows the presence of α7–containing receptors in the A549 but not in H1975 cells, while tumour samples show an increase in the level of CHRNA5 subunit mRNA with no significative change of CHRNA7 mRNAs. Nicotine, in a dose-dependent manner, significantly increases the A549 cell viability and proliferation but has no effect on H1975 cells. To determine whether the α7 nAChR might mediate the nicotine-induced proliferation we treated A549 cells with α-bungarotoxin (α-bgtx), an α7 selective antagonist and we found that α-bgtx blocks the nicotine-induced proliferation in A549 cells . Nicotine enhances the migration of A549 cells and induces a selective time‐dependent activation of phospho-Erk and phospho­Akt pathways in A549 cells. Conclusion Collectively our data suggests that nicotine promotes proliferation, invasion and migration of NSCLC A549 by activating the Akt/ERK pathway. We would therefore investigate the role of drugs targeting nAChRs for new therapeutic strategy.