Cigarette smoking is strongly correlated with the onset of nonsmall cell lung cancer (NSCLC). Nicotine, an active component of cigarettes, has been found to induce proliferation of lung cancer cell lines. In addition, nicotine can induce angiogenesis and confer resistance to apoptosis. All these events are mediated through the nicotinic acetylcholine receptors (nAChRs) on lung cancer cells. In this study, we demonstrate that nicotine can promote anchorage-independent growth in NSCLCs. In addition, nicotine also induces morphological changes characteristic of a migratory, invasive phenotype in NSCLCs on collagen gel. These morphological changes were similar to those induced by the promigratory growth factor VEGF. The proinvasive effects of nicotine were mediated by a7-nAChRs on NSCLCs. RT-PCR analysis showed that the a7-nAChRs were also expressed on human breast cancer and pancreatic cancer cell lines. Nicotine was found to promote proliferation and invasion in human breast cancer. The proinvasive effects of nicotine were mediated via a nAChR, Src and calcium-dependent signaling pathway in breast cancer cells. In a similar fashion, nicotine could also induce proliferation and invasion of Aspc1 pancreatic cancer cells. Most importantly, nicotine could induce changes in gene expression consistent with epithelial to mesenchymal transition (EMT), characterized by reduction of epithelial markers like E-cadherin expression, ZO-1 staining and concomitant increase in levels of mesenchymal proteins like vimentin and fibronectin in human breast and lung cancer cells. Therefore, it is probable that the ability of nicotine to induce invasion and EMT may contribute to the progression of breast and lung cancers. ' 2008 Wiley-Liss, Inc.Key words: lung cancer; nicotine; epithelial-mesenchymal transition; tumor progression; metastasis Cigarette smoke is the strongest documented risk factor for the development of lung cancer, accounting for about 157,000 deaths every year in the US. 1 A significant proportion of nonsmall cell lung cancer (NSCLC) cases are detected only in the advanced stage after the onset of metastasis, leading to a remarkably low 5-year survival rate (about 15%) in patients. 1 Tobacco-derived carcinogens like 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N 0 -nitrosonornicotine (NNN) are known to form DNA adducts, mutating vital growth regulatory genes like p53 and Ras, initiating oncogenesis. [2][3][4] In addition, several lines of evidence indicate that cigarette smoking correlates with increased metastasis of lung, pancreatic, breast and bladder cancers. [5][6][7] Although cigarette smoke is a complex mixture of over 4,000 compounds, nicotine has been shown the major addictive component of cigarettes. 8-10 Nicotine, while not carcinogenic by itself, has been shown to induce proliferation and angiogenesis in several experimental models 11-14 ; these effects occurred at concentrations normally found in the blood stream of smokers (10 28 -10 27 M). 12 These levels can vary greatly in smokers, and uri...

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While cancer is commonly described as "a disease of the genes", it is also associated with massive metabolic reprogramming that is now accepted as a disease "Hallmark". This programming is complex and often involves metabolic cooperativity between cancer cells and their surrounding stroma. Indeed, there is emerging clinical evidence that interrupting a cancer's metabolic program can improve patients' outcomes. The most commonly observed and well-studied metabolic adaptation in cancers is the fermentation of glucose to lactic acid, even in the presence of oxygen, also known as "aerobic glycolysis" or the "Warburg Effect". Much has been written about the mechanisms of the Warburg effect and this remains a topic of great debate. However, herein we will focus on an important sequela of this metabolic program: the acidification of the tumor microenvironment. Rather than being an epiphenomenon, it is now appreciated that this acidosis is a key player in cancer somatic evolution and progression to malignancy. Adaptation to acidosis induces and selects for malignant behaviors, such as increased invasion and metastasis, chemoresistance, and inhibition of immune surveillance. However, the metabolic reprogramming that occurs during adaptation to acidosis also introduces therapeutic vulnerabilities. Thus, tumor acidosis is a relevant therapeutic target, and we describe herein four approaches to accomplish this: 1) neutralizing acid directly with buffers; 2) targeting metabolic vulnerabilities revealed by acidosis, 3) development of acid-activatable drugs and nanomedicines, and 4) inhibiting metabolic processes responsible for generating acids in the first place.

Nicotine induced the nuclear translocation of ARRB1 and showed increased expression of proliferative and survival genes, thereby contributing to the growth and progression of NSCLCs.