title: Cholinergic muscarinic receptor activation augments murine intestinal epithelial cell proliferation and tumorigenesis.
abstract: BACKGROUND
  Previously, we showed that M3 muscarinic receptor (M3R; gene name Chrm3) deficiency attenuates murine intestinal neoplasia, supporting the hypothesis that muscarinic receptors play an important role in intestinal tumorigenesis.
  
  
  METHODS
  To test this hypothesis, in the present study we treated mice with bethanechol, a non-selective muscarinic receptor agonist without nicotinic receptor activity, and examined its effects on azoxymethane (AOM)-induced colon neoplasia. Mice were provided with drinking water containing 400 μg/mL bethanechol chloride or water without additions (control) for a total of 20 weeks, a period that included the initial 6 weeks when mice received intraperitoneal injections of AOM.
  
  
  RESULTS
  When euthanized at week 20, control mice had 8.0 ± 1.3 tumors per animal, whereas bethanechol-treated mice had 10.4 ± 1.5 tumors per mouse (mean ± SE; P = 0.023), a 30% increase. Strikingly, tumor volume per animal was increased 52% in bethanechol-treated compared with control mice (179.7 ± 21.0 vs. 111. 8 ± 22.4 mm(3); P = 0.047). On histological examination, bethenechol-treated mice also had more adenocarcinomas per animal (8.0 ± 1.0 vs. 4.1 ± 0.6 for control mice, P = 0.0042). Cell proliferation in both normal mucosa and adenocarcinomas was increased in bethanechol-treated compared to control mice. Also, in tumors, bethanechol treatment increased expression of Chrm3, Egfr and post-Egfr signaling molecules Myc and cyclin D1. Bethanechol treatment increased the thickness of normal colonic mucosa and the expression of selected matrix metalloproteinase (Mmp) genes, including Mmp7, Mmp10 and Mmp13.
  
  
  CONCLUSIONS
  These findings support a prominent role for muscarinic receptors in colon neoplasia, and identify post-receptor signaling molecules as potential therapeutic targets.
authors.affiliation: Division of Gastroenterology and Hepatology, Veterans Affairs Maryland Health Care System, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: Zhongsheng
authors.initials: Z
authors.lastname: Peng
authors.forename: Jonathon
authors.initials: J
authors.lastname: Heath
authors.forename: Cinthia
authors.initials: C
authors.lastname: Drachenberg
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Raufman
authors.forename: Guofeng
authors.initials: G
authors.lastname: Xie
mesh_terms: D000230:Adenocarcinoma / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology*; D000818:Animals; D001397:Azoxymethane; D018723:Bethanechol / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000187:drug effects; D003110:Colonic Neoplasms / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology*; D019938:Cyclin D1 / Q000235:genetics; D051546:Cyclooxygenase 2 / Q000235:genetics; D066246:ErbB Receptors / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics; D007413:Intestinal Mucosa / Q000187:drug effects / Q000473:pathology; D008297:Male; D053506:Matrix Metalloproteinase 10 / Q000235:genetics; D053509:Matrix Metalloproteinase 13 / Q000235:genetics; D020783:Matrix Metalloproteinase 7 / Q000235:genetics; D051379:Mice; D018721:Muscarinic Agonists / Q000494:pharmacology; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D043587:Receptor, Muscarinic M3 / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D047368:Tumor Burden
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D018721:Muscarinic Agonists; C489428:Myc protein, mouse; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D043587:Receptor, Muscarinic M3; D018723:Bethanechol; D019938:Cyclin D1; D051546:Cyclooxygenase 2; D066246:ErbB Receptors; D053509:Matrix Metalloproteinase 13; D053506:Matrix Metalloproteinase 10; D020783:Matrix Metalloproteinase 7; D001397:Azoxymethane