title: The ERK1/2 and mTORC1 Signaling Pathways Are Involved in the Muscarinic Acetylcholine Receptor-Mediated Proliferation of SNU-407 Colon Cancer Cells.
abstract: Muscarinic acetylcholine receptors (mAChRs) regulate diverse cellular functions, including cell growth and proliferation, via multiple signaling pathways. Previously, we showed that mAChRs stimulate the MEK1/2-ERK1/2-RSK pathway in SNU-407 colon cancer cells and subsequently promote cell proliferation. In this study, we provide evidence that the PI3K-Akt-mTORC1-S6K1 pathway is activated by mAChRs in SNU-407 cells and that this pathway is associated with protein biosynthesis and cell proliferation. When the cells were treated with the cholinergic agonist carbachol, Akt was activated in a dose- and time-dependent fashion. This carbachol effect was almost completely blocked by the PI3K inhibitor LY294002, implying that PI3K is responsible for the Akt activation. S6K1, a major downstream target of mTORC1, was also activated by carbachol in a temporal profile similar to that of the Akt activation. This carbachol-stimulated S6K1 activation was abrogated by LY294002 or the mTORC1 inhibitor rapamycin, supporting the notion that mAChRs mediate S6K1 activation via the PI3K-Akt-mTORC1 pathway. We observed that global protein biosynthesis, monitored by puromycin incorporation, was strongly increased by carbachol in an atropine-sensitive manner. Inhibition experiments indicated that the ERK1/2 and mTORC1 signaling pathways may be involved in carbachol-stimulated global protein biosynthesis. We also found that treating SNU-407 cells with LY294002 or rapamycin significantly suppressed carbachol-stimulated cell proliferation. In the presence of the MEK1/2 inhibitor U0126, cell proliferation was further reduced by rapamycin treatment. Our data thus suggest that both the MEK1/2-ERK1/2 and mTORC1 pathways play important roles in mAChR-mediated cell proliferation in SNU-407 colon cancer cells. J. Cell. Biochem. 117: 2854-2863, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Chungbuk National University, Cheongju, 28644, South Korea.
authors.forename: Yang-Seo
authors.initials: YS
authors.lastname: Park
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Chungbuk National University, Cheongju, 28644, South Korea.
authors.forename: Ziyu
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Chungbuk National University, Cheongju, 28644, South Korea.
authors.forename: Bala Murali Krishna
authors.initials: BM
authors.lastname: Vasamsetti
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Chungbuk National University, Cheongju, 28644, South Korea. namjcho@cbnu.ac.kr.
authors.forename: Nam Jeong
authors.initials: NJ
authors.lastname: Cho
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002217:Carbachol / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects*; D018679:Cholinergic Agonists / Q000494:pharmacology; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D000076222:Mechanistic Target of Rapamycin Complex 1; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000737:chemistry* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D018679:Cholinergic Agonists; D046912:Multiprotein Complexes; D011976:Receptors, Muscarinic; D002217:Carbachol; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3
keywords: CELL PROLIFERATION; COLON CANCER; ERK1/2; MUSCARINIC ACETYLCHOLINE RECEPTORS; mTORC1