Distinct roles of cholinergic receptors in small cell lung cancer cells.
BACKGROUND
Cholinergic receptors are expressed in small cell lung cancer (SCLC); however, the distinct functions of muscarinic cholinergic receptor 3 (mAChR3) and the nicotinic cholinergic receptor (nAChR) in SCLC have not yet been completely elucidated.


METHODS
RT-PCR and Western blotting were used to investigate the expression of cholinergic receptors. Flow cytometry was used to detect the integrin expression. Cell proliferation, adhesion and migration assays were carried out in vitro to determine the roles of the cholinergic receptors in SBC3 human SCLC cells.


RESULTS
Both mAChR3 and nAChR were expressed in the SBC3 cells. Acetylcholine iodide (Ach) stimulated SBC3 cell proliferation, adhesion and migration toward fibronectin (Fn). The mAChR3 antagonist, 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP), or the nAChR antagonist, mecamylamine hydrochloride (Meca), inhibited SBC3 cell proliferation in the presence or the absence of exogenous Ach. 4-DAMP abrogated cell adhesion and migration toward Fn induced by Ach, while Meca had no effect. Interestingly, Ach did not alter Fn receptor (alphavbeta1 or alpha5beta1 integrin) expression, while anti-beta1 integrin antibody or anti-alphav and anti-alpha5 integrin antibody completely abrogated cell adhesion to Fn induced by Ach.


CONCLUSIONS
Both mAChR3 and nAChR are expressed in SCLC. SBC3 cell proliferation is regulated in vitro through both cholinergic receptors. In contrast, SBC3 cell migration and adhesion toward Fn are modulated only by mAChR. Moreover, the stimulatory effects of Ach on cell adhesion and migration through mAChR3 are presumably modulated by functional alteration of alphavbeta1 and alpha5beta1 integrin, but not by any variation in their expression. The mAChR3 antagonist may therefore be a beneficial therapeutic modality for SCLC patients, especially those with chronic obstructive pulmonary disease (COPD) as a comorbidity.
Department of Respiratory Medicine and Research Institute for Diseases of Old Ages, Juntendo University, School of Medicine, 2-1-1 Hongo, Bunkyo-Ku, Tokyo 113-8421, Japan.
Shuxiang
S
Zhang
Shinsaku
S
Togo
Kunihiko
K
Minakata
Tao
T
Gu
Rina
R
Ohashi
Ken
K
Tajima
Akiko
A
Murakami
Shinichiro
S
Iwakami
Jin
J
Zhang
Canmao
C
Xie
Kazuhisa
K
Takahashi
D015153:Blotting, Western; D018288:Carcinoma, Small Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002448:Cell Adhesion / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D018679:Cholinergic Agonists / Q000494:pharmacology; D004365:Drugs, Chinese Herbal / Q000494:pharmacology; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011134:Polysaccharides / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D043587:Receptor, Muscarinic M3 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D011978:Receptors, Nicotinic / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018679:Cholinergic Agonists; D004365:Drugs, Chinese Herbal; D018727:Muscarinic Antagonists; D010880:Piperidines; D011134:Polysaccharides; D012333:RNA, Messenger; D043587:Receptor, Muscarinic M3; D011978:Receptors, Nicotinic; C475099:achyranthan; C042375:4-diphenylacetoxy-1,1-dimethylpiperidinium