Nicotine Stimulates Human Lung Cancer Cell Growth by Inducing Fibronectin Expression

Abstract

The mechanisms by which tobacco promotes lung cancer remain incompletely understood. Herein, we report that nicotine, a major component of tobacco, promotes the proliferation of cultured non-small cell lung carcinoma (NSCLC) cells; this effect was most noticeable at 5 days. However, nicotine had no effect on apoptosis of NSCLC cells. In experiments designed to unveil the mechanisms for this effect, we found that nicotine also stimulated mRNA and protein expression of fibronectin. Fibronectin is a matrix glycoprotein that regulates important cellular processes (e.g., adhesion, proliferation, and differentiation) and is highly expressed in tobacco-related lung disorders. Of note, reagents against the integrin alpha5beta1 (antibodies, RGD peptides, alpha5 shRNA) blocked the mitogenic effects of nicotine. Thus, nicotine stimulated NSCLC cell proliferation indirectly via fibronectin induction. We then focused on the mechanisms responsible for nicotine-induced fibronectin expression in NSCLC cells and found that nicotine stimulated the surface expression of alpha7 nicotinic acetylcholine receptor (alpha7 nAChR), and that alpha-bungarotoxin, an inhibitor of alpha7 nAChR, abolished the nicotine-induced fibronectin response. The fibronectin-inducing effects of nicotine were associated with activation of extracellular signal-regulated kinase (ERK) and phosphoinositide 3-kinase (PI3-K)/mammalian target of rapamycin (mTOR) signaling pathways, and were abrogated by inhibitors of ERK (PD98059), PI3-K (LY294002), and mTOR (rapamycin), but not by inhibitors of protein kinase (PK)C (calphostin C) and PKA (H89). These observations suggest that nicotine stimulates NSCLC proliferation through induction of fibronectin, and that these events are mediated through nAChR-mediated signals that include ERK and PI3-K/mTOR pathways. This work highlights the role of fibronectin and alpha5beta1 integrins as potential targets for anti-lung cancer therapies.

ID1 Facilitates the Growth and Metastasis of Non-Small Cell Lung Cancer in Response to Nicotinic Acetylcholine Receptor and Epidermal Growth Factor Receptor Signaling

“…Fibronectin (pFN, 1.2 kb) and vimentin (VimPro, 1.5 kb) promoter-luciferase constructs were kindly provided by Jesse Roman (Emory University) and C. Gilles (Liege University, Belgium) (15,72). ID1 promoter-luciferase construct (ID1-Luc, 2.2 kb) was a kind gift from PierreYves Desprez (California Pacific Medical Center, San Francisco, CA) (14,57).…”

FoxM1 mediated resistance to gefitinib in non-smallcell lung cancer cells

“…A Western blot was performed with whole cell extracts by the protocols described previously [21] . The antibodies used were anti-β-actin antibody (1:5000, Abcam), rabbit polyclonal antiFoxM1 antibody (1:2000, Santa Cruz Biotechnology), rabbit monoclonal anti-survivin antibody (1:1000, CST) or rabbit polyclonal anti-cyclin B1 antibody (1:1000, CST), rabbit monoclonal anti-Skp2 antibody (1:1000, CST), rabbit monoclonal anti-Aurora B kinase antibody (1:1000, CST), rabbit monoclonal anti-PLK1 antibody (1:1000, CST), and rabbit monoclonal anti-CDC25B antibody (1:1000, CST).…”

Binding of MMP-9-degraded fibronectin to β6 integrin promotes invasion via the FAK-Src-related Erk1/2 and PI3K/Akt/Smad-1/5/8 pathways in breast cancer

“…αvβ6 integrin binds FN in an RGD-dependent manner (7). FN has been implicated in the development of multiple types of human cancer (8,9) and is associated with cell migration and invasion in metastatic models (9,10). In breast cancer, FN has shown higher expression than that in normal breast parenchyma, with a different distribution (11).…”