title: The GPER agonist G-1 induces mitotic arrest and apoptosis in human vascular smooth muscle cells independent of GPER.
abstract: The G protein-coupled estrogen receptor (GPER) has been implicated in the regulation of smooth muscle cell (SMC) proliferation. The GPER selective agonist G-1 has been a useful tool for exploring the biological roles of GPER in a variety of experimental settings, including SMC proliferation. The present study, originally designed to investigate cellular and signaling mechanisms underlying the regulatory role of GPER in vascular SMC proliferation using G-1, unexpectedly revealed off-target effects of G-1. G-1(1-10 μM) inhibited bromodeoxyuridine (BrdU) incorporation of human SMCs and caused G2/M cell accumulation. G-1 treatment also increased mitotic index concurrent with a decrease in phosphorylation of Cdk1 (Tyr 15) and an increase in phosphorylation of the mitotic checkpoint protein BuBR1. Furthermore, G-1 caused microtubule disruption, mitotic spindle damage, and tubulin depolymerization. G-1 induced cell apoptosis as indicated by the appearance of TUNEL-positive and annexin V-positive cells with enhanced cleavage of caspases 3 and 9. However, neither the GPER antagonist G-15 nor the MAPK kinase inhibitor PD98059 prevented these G-1 effects. Down-regulation of GPER or p44/42 MAPK with siRNA transfection also did not affect the G-1-induced apoptosis. We conclude that G-1 inhibits proliferation of SMCs through mechanisms involving mitotic arrest and apoptosis, independent of GPER and the MAPK pathway.
authors.affiliation: The Smooth Muscle Research Group, Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Yu
authors.initials: Y
authors.lastname: Gui
authors.forename: Zhan
authors.initials: Z
authors.lastname: Shi
authors.forename: ZengYong
authors.initials: Z
authors.lastname: Wang
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Li
authors.forename: Can
authors.initials: C
authors.lastname: Xu
authors.forename: RuiJuan
authors.initials: R
authors.lastname: Tian
authors.forename: XinXing
authors.initials: X
authors.lastname: Song
authors.forename: Michael P
authors.initials: MP
authors.lastname: Walsh
authors.forename: Dong
authors.initials: D
authors.lastname: Li
authors.forename: Jie
authors.initials: J
authors.lastname: Gao
authors.forename: Xi-Long
authors.initials: XL
authors.lastname: Zheng
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D003517:Cyclopentanes / Q000494:pharmacology*; D004967:Estrogens / Q000378:metabolism; D006801:Humans; D008938:Mitosis / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011804:Quinolines / Q000494:pharmacology*; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled / Q000819:agonists*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: C517943:1-(4-(6-bromobenzo(1,3)dioxol-5-yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta(c)quinolin-8-yl)ethanone; D003517:Cyclopentanes; D004967:Estrogens; C109584:GPER1 protein, human; D011804:Quinolines; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled