title: Gonadotropin-releasing hormone type II (GnRH-II) agonist regulates the invasiveness of endometrial cancer cells through the GnRH-I receptor and mitogen-activated protein kinase (MAPK)-dependent activation of matrix metalloproteinase (MMP)-2.
abstract: BACKGROUND
  More than 25% of patients diagnosed with endometrial carcinoma have an invasive primary cancer accompanied by metastases. Gonadotropin-releasing hormone (GnRH) plays an important role in reproduction. In mammals, expression of GnRH-II is higher than GnRH-I in reproductive tissues. Here, we examined the effect of a GnRH-II agonist on the motility of endometrial cancer cells and its mechanism of action in endometrial cancer therapy.
  
  
  METHODS
  Immunoblotting and immunohistochemistry (IHC) were used to determine the expression of the GnRH-I receptor protein in human endometrial cancer. The activity of MMP-2 in the conditioned medium was determined by gelatin zymography. Cell motility was assessed by invasion and migration assay. GnRH-I receptor si-RNA was applied to knockdown GnRH-I receptor.
  
  
  RESULTS
  The GnRH-I receptor was expressed in the endometrial cancer cells. The GnRH-II agonist promoted cell motility in a dose-dependent manner. The GnRH-II agonist induced the phosphorylation of ERK1/2 and JNK, and the phosphorylation was abolished by ERK1/2 inhibitor (U0126) and the JNK inhibitor (SP600125). Cell motility promoted by GnRH-II agonist was suppressed in cells that were pretreated with U0126 and SP600125. Moreover, U0126 and SP600125 abolished the GnRH-II agonist-induced activation of MMP-2. The inhibition of MMP-2 with MMP-2 inhibitor (OA-Hy) suppressed the increase in cell motility in response to the GnRH-II agonist. Enhanced cell motility mediated by GnRH-II agonist was also suppressed by the knockdown of the endogenous GnRH-I receptor using siRNA.
  
  
  CONCLUSIONS
  Our study indicates that GnRH-II agonist promoted cell motility of endometrial cancer cells through the GnRH-I receptor via the phosphorylation of ERK1/2 and JNK, and the subsequent, MAPK-dependent activation of MMP-2. Our findings represent a new concept regarding the mechanism of GnRH-II-induced cell motility in endometrial cancer cells and suggest the possibility of exploring GnRH-II as a potential therapeutic target for the treatment of human endometrial cancer.
authors.affiliation: Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital Linkou Medical Center, Chang Gung University School of Medicine, Taoyuan 333, Taiwan. danielwu@cgmh.org.tw
authors.forename: Hsien-Ming
authors.initials: HM
authors.lastname: Wu
authors.forename: Hsin-Shih
authors.initials: HS
authors.lastname: Wang
authors.forename: Hong-Yuan
authors.initials: HY
authors.lastname: Huang
authors.forename: Chyong-Huey
authors.initials: CH
authors.lastname: Lai
authors.forename: Chyi-Long
authors.initials: CL
authors.lastname: Lee
authors.forename: Yung-Kuei
authors.initials: YK
authors.lastname: Soong
authors.forename: Peter Ck
authors.initials: PC
authors.lastname: Leung
mesh_terms: D000873:Anthracenes / Q000494:pharmacology; D002070:Butadienes / Q000494:pharmacology; D002277:Carcinoma / Q000378:metabolism* / Q000473:pathology*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D016889:Endometrial Neoplasms / Q000378:metabolism* / Q000473:pathology*; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D055785:Gene Knockdown Techniques; D007987:Gonadotropin-Releasing Hormone / Q000819:agonists; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D011966:Receptors, LHRH / Q000235:genetics / Q000378:metabolism*
chemical_list: D000873:Anthracenes; D002070:Butadienes; C484844:GNRHR protein, human; D006877:Hydroxamic Acids; D009570:Nitriles; D011966:Receptors, LHRH; C113580:U 0126; C474031:N-hydroxy-9-octadecenamide; C432165:pyrazolanthrone; D007987:Gonadotropin-Releasing Hormone; D020928:Mitogen-Activated Protein Kinases; D020778:Matrix Metalloproteinase 2