title: Progestin and G protein-coupled receptor 30 inhibit mitogen-activated protein kinase activity in MCF-7 breast cancer cells.
abstract: We have previously shown that the G protein-coupled receptor (GPR)30 is critical for progestin-induced growth inhibition. In this study, we addressed signal transduction pathways involved in progestin-mediated signaling. Progestin could not provide any additional growth inhibitory effect to MCF-7 cells treated with specific MAPK kinase inhibitors, PD98059 and U0126. Medroxyprogesteroneacetate (MPA) induced a late (22-23 h) decrease in ERK-1 and -2 activities verified by immunoblotting and kinase assay. The inactivation was abrogated by antiprogestin. Transient expression of GPR30 decreased ERK-1 and -2 activity; and in the cells in which GPR30 expression was decreased by the antisense, ERK activities were increased. The antisense-expressing cells were able to significantly resist the growth-inhibitory effect of the MAPK kinase inhibitors PD98059 and U0126 but not that of other factors tested. Interestingly, the decrease of ERK activity induced by MPA was abrogated by GPR30 antisense. Collectively, these results show that MAPK activity is inhibited by progestin and GPR30 and suggest that progestin-induced ERK inactivation is mediated through GPR30. Coupled with our previous findings, the data imply that up-regulation of GPR30 by progestin leads to ERK-1 and -2 inactivation associated with MPA-induced growth inhibition.
authors.affiliation: Department of Cell Biology, Medical School, University of Tampere, 33014 Tampere, Finland. ta55935@uta.fi
authors.forename: Tytti M
authors.initials: TM
authors.lastname: Ahola
authors.forename: Niina
authors.initials: N
authors.lastname: Alkio
authors.forename: Tommi
authors.initials: T
authors.lastname: Manninen
authors.forename: Timo
authors.initials: T
authors.lastname: Ylikomi
mesh_terms: D001943:Breast Neoplasms / Q000201:enzymology* / Q000473:pathology; D002070:Butadienes / Q000494:pharmacology; D002455:Cell Division; D016373:DNA, Antisense / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005419:Flavonoids / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology*; D015870:Gene Expression; D006801:Humans; D017258:Medroxyprogesterone Acetate / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors*; D009570:Nitriles / Q000494:pharmacology; D011372:Progestins / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000235:genetics / Q000502:physiology*; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled; D015398:Signal Transduction; D014407:Tumor Cells, Cultured
chemical_list: D002070:Butadienes; D016373:DNA, Antisense; D004791:Enzyme Inhibitors; D005419:Flavonoids; C109584:GPER1 protein, human; D009570:Nitriles; D011372:Progestins; D011956:Receptors, Cell Surface; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled; C113580:U 0126; D017258:Medroxyprogesterone Acetate; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one