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Recent case-controlled clinical studies show that bronchioalveolar carcinomas (BAC) are correlated with smoking. Nicotine, the addictive component of cigarettes, accelerates cell proliferation through nicotinic acetylcholine receptors (nAChR). In this study, we show that human BACs produce acetylcholine (ACh) and contain several cholinergic factors including acetylcholinesterase (AChE), choline acetyltransferase (ChAT), choline transporter 1 (CHT1, SLC5A7), vesicular acetylcholine transporter (VAChT, SLC18A3), and nACh receptors (AChRs, CHRNAs). Nicotine increased the production of ACh in human BACs, and ACh acts as a growth factor for these cells. Nicotine-induced ACh production was mediated by α7-, α3β2-, and β3-nAChRs, ChAT and VAChT pathways. We observed that nicotine upregulated ChAT and VAChT. Therefore, we conjectured that VAChT antagonists, such as vesamicol, may suppress the growth of human BACs. Vesamicol induced potent apoptosis of human BACs in cell culture and nude mice models. Vesamicol did not have any effect on EGF or insulin-like growth factor-II–induced growth of human BACs. siRNA-mediated attenuation of VAChT reversed the apoptotic activity of vesamicol. We also observed that vesamicol inhibited Akt phosphorylation during cell death and that overexpression of constitutively active Akt reversed the apoptotic activity of vesamicol. Taken together, our results suggested that disruption of nicotine-induced cholinergic signaling by agents such as vesamicol may have applications in BAC therapy. Cancer Res; 73(4); 1328–39. ©2012 AACR.

PDF file - 490K, Figure S1: Cell line authentication data Figure S2: Full screen western blots for ChAT, VAChT, AChE and CHT1 Figure S3: Immunohistochemistry of ChAT and VAChT in normal human lung tissues Figure S4: Nicotine-induced ACh production in human BAC requires nAChRs, VAChT, and CHT1 Figure S5: VAChT and ChAT are expressed on human BACs Figure S6: Transfection of VAChT siRNA and Sigma-R siRNA suppress the expression of these proteins in human BACs Figure S7: Effect of VAChT siRNA on the apoptotic activity of vesamicol in nicotine-treated BACs Figure S8: Overexpression of pcDNA3-HA-Akt-CA in A549 and H358 human BAC cells