title: Different muscarinic receptor subtypes modulate proliferation of primary human detrusor smooth muscle cells via Akt/PI3K and map kinases.
abstract: While acetylcholine (ACh) and muscarinic receptors in the bladder are mainly known for their role in the regulation of smooth muscle contractility, in other tissues they are involved in tissue remodelling and promote cell growth and proliferation. In the present study we have used primary cultures of human detrusor smooth muscle cells (HDSMCs), in order to investigate the role of muscarinic receptors in HDSMC proliferation. Samples were obtained as discarded tissue from men >65 years undergoing radical cystectomy for bladder cancer and cut in pieces that were either immediately frozen or placed in culture medium for the cell culture establishment. HDSMCs were isolated from samples, propagated and maintained in culture. [(3)H]-QNB radioligand binding on biopsies revealed the presence of muscarinic receptors, with a Kd of 0.10±0.02nM and a Bmax of 72.8±0.1fmol/mg protein. The relative expression of muscarinic receptor subtypes, based on Q-RT-PCR, was similar in biopsies and HDSMC with a rank order of M2≥M3>M1>M4>M5. The cholinergic agonist carbachol (CCh, 1-100μM) concentration-dependently increased [(3)H]-thymidine incorporation (up to 46±4%). This was concentration-dependently inhibited by the general muscarinic receptor antagonist atropine and by subtype-preferring antagonists with an order of potency of darifenacin >4-DAMP>AF-DX 116. The CCh-induced cell proliferation was blocked by selective PI-3 kinase and ERK activation inhibitors, strongly suggesting that these intracellular pathways mediate, at least in part, the muscarinic receptor-mediated cell proliferation. This work shows that M2 and M3 receptors can mediate not only HDSM contraction but also proliferation; they may also contribute bladder remodelling including detrusor hypertrophy.
authors.affiliation: Urology Unit, Istituto Clinico Città di Brescia, Brescia, Italy. dr.arrighi@live.it
authors.forename: Nicola
authors.initials: N
authors.lastname: Arrighi
authors.forename: Serena
authors.initials: S
authors.lastname: Bodei
authors.forename: Danilo
authors.initials: D
authors.lastname: Zani
authors.forename: Martin C
authors.initials: MC
authors.lastname: Michel
authors.forename: Claudio
authors.initials: C
authors.lastname: Simeone
authors.forename: Sergio
authors.initials: S
authors.lastname: Cosciani Cunico
authors.forename: Pierfranco
authors.initials: P
authors.lastname: Spano
authors.forename: Sandra
authors.initials: S
authors.lastname: Sigala
mesh_terms: D000368:Aged; D001285:Atropine / Q000494:pharmacology; D001572:Benzofurans / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D049109:Cell Proliferation; D002478:Cells, Cultured; D018679:Cholinergic Agonists / Q000494:pharmacology; D015870:Gene Expression; D006801:Humans; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D018727:Muscarinic Antagonists / Q000494:pharmacology; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010880:Piperidines / Q000494:pharmacology; D010890:Pirenzepine / Q000031:analogs & derivatives / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011759:Pyrrolidines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000502:physiology*; D001743:Urinary Bladder / Q000166:cytology*
chemical_list: D001572:Benzofurans; D018679:Cholinergic Agonists; D018727:Muscarinic Antagonists; D010880:Piperidines; D011759:Pyrrolidines; D012333:RNA, Messenger; D011976:Receptors, Muscarinic; D010890:Pirenzepine; D001285:Atropine; C042375:4-diphenylacetoxy-1,1-dimethylpiperidinium; D002217:Carbachol; C101207:darifenacin; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; C048593:otenzepad
keywords: Human detrusor smooth; Muscarinic receptors; Muscle cell; Proliferation