title: Epidermal growth factor-induced GnRH-II synthesis contributes to ovarian cancer cell invasion.
abstract: GnRH-II modulates ovarian cancer cells invasion and is expressed in normal ovary and ovarian epithelial cancer cells; however, the upstream regulator(s) of GnRH-II expression in these cells remains unclear. We now demonstrate that epidermal growth factor (EGF) increases GnRH-II mRNA levels in several human ovarian carcinoma cell lines and up-regulates GnRH-II promoter activity in OVCAR-3 cells in a dose-dependent manner, whereas an EGF receptor inhibitor (AG148) abolishes EGF-induced increases in GnRH-II promoter activity and GnRH-II mRNA levels. EGF increases the phosphorylation of cAMP-responsive element-binding protein (p-CREB) and its association with the coregulator, CCAAT/enhancer binding protein beta, whereas blocking the EGF-induced ERK1/2 phosphorylation with MAPK inhibitors (PD98059/U0126) markedly reduced these effects. Moreover, depletion of CREB using small interfering RNA attenuated EGF-induced GnRH-II promoter activity. Chromatin immunoprecipitation assays demonstrated that EGF induces p-CREB binding to a cAMP responsive-element within the GnRH-II promoter, likely in association with CCAAT/enhancer binding protein beta, and mutagenesis of this cAMP responsive-element prevented EGF-induced GnRH-II promoter activity in OVCAR-3 cells. Importantly, GnRH-II acts additively with EGF to promote invasion of OVCAR-3 and CaOV-3 cells, but not SKOV-3 cells that express low levels of GnRH receptor (GnRHR). Treatment with GnRHR small interfering RNA also partially inhibited the EGF-induced invasion of OVCAR-3 and CaOV-3 cells. Furthermore, EGF treatment transiently increases GnRHR levels in OVCAR-3 and CaOV-3, which likely accentuates the effects of increase GnRH-II production on cell invasion. These results provide evidence that EGF is an upstream regulator of the autocrine actions of GnRH-II on the invasive properties of ovarian cancer cells.
authors.affiliation: Department of Obstetrics and Gynaecology, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada V6H 3V5.
authors.forename: Song Ling
authors.initials: SL
authors.lastname: Poon
authors.forename: Gareth T
authors.initials: GT
authors.lastname: Hammond
authors.forename: Peter C K
authors.initials: PC
authors.lastname: Leung
mesh_terms: D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism; D045744:Cell Line, Tumor; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D009361:Neoplasm Invasiveness; D010051:Ovarian Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics
chemical_list: D022782:CCAAT-Enhancer-Binding Protein-beta; D017362:Cyclic AMP Response Element-Binding Protein; D012333:RNA, Messenger; D007987:Gonadotropin-Releasing Hormone; D004815:Epidermal Growth Factor; C047717:LHRH, His(5)-Trp(7)-Tyr(8)-; D020928:Mitogen-Activated Protein Kinases