Nicotinic acetylcholine receptors in cancer: multiple roles in proliferation and inhibition of apoptosis

Nicotinic acetylcholine receptors (nAChRs) constitute a heterogeneous family of ion channels that mediate fast synaptic transmission in neurons. They have also been found on non-neuronal cells such as bronchial epithelium and keratinocytes, underscoring the idea that they have functions well beyond neurotransmission. Components of cigarette smoke, including nicotine and NNK [4-(methyinitrosamino)-l-(3-pyridyl)-l-butanone], are agonists of nAChRs. Given the association of tobacco use with several diseases, the non-neuronal nAChR signaling pathway has considerable implications for cancer and cardiovascular disease. Recent studies have shown that alpha 7 is the main nAChR subunit that mediates the proliferative effects of nicotine in cancer cells. As a result, a7 nAChR might be a valuable molecular target for therapy of cancers such as lung cancer and mesothelioma. Future studies involving the design of nAChR antagonists with improved selectivity might identify novel strategies for the treatment of tobacco-related cancers. Here we review the cellular roles of non-neuronal nAChRs, including regulation of cell proliferation, angiogenesis, apoptosis, migration, invasion and secretion.