Gene Summary

Gene:GNRHR; gonadotropin releasing hormone receptor
Summary:This gene encodes the receptor for type 1 gonadotropin-releasing hormone. This receptor is a member of the seven-transmembrane, G-protein coupled receptor (GPCR) family. It is expressed on the surface of pituitary gonadotrope cells as well as lymphocytes, breast, ovary, and prostate. Following binding of gonadotropin-releasing hormone, the receptor associates with G-proteins that activate a phosphatidylinositol-calcium second messenger system. Activation of the receptor ultimately causes the release of gonadotropic luteinizing hormone (LH) and follicle stimulating hormone (FSH). Defects in this gene are a cause of hypogonadotropic hypogonadism (HH). Alternative splicing results in multiple transcript variants encoding different isoforms. More than 18 transcription initiation sites in the 5' region and multiple polyA signals in the 3' region have been identified for this gene. [provided by RefSeq, Jul 2008]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:gonadotropin-releasing hormone receptor
Source:NCBIAccessed: 16 March, 2017


What does this gene/protein do?
Show (9)
Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 16 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • beta Catenin
  • Ovarian Cancer
  • Breast Cancer
  • Transfection
  • Young Adult
  • Sulfonamides
  • Immunohistochemistry
  • Single Nucleotide Polymorphism
  • RHOA
  • siRNA
  • p38 Mitogen-Activated Protein Kinases
  • Ovary
  • Receptors, LH
  • Membrane Proteins
  • Cancer Gene Expression Regulation
  • Base Sequence
  • Mitogen-Activated Protein Kinases
  • Gene Expression
  • Adrenocortical Cancer
  • Cell Proliferation
  • Adenoma
  • Chromosome 4
  • Genotype
  • Gonadotropin-Releasing Hormone
  • Mutation
  • Prostate Cancer
  • Up-Regulation
  • Uterine Cancer
  • Receptors, Interleukin
  • Messenger RNA
  • Neoplasm Invasiveness
  • Versicans
  • Apoptosis
  • Protein Precursors
  • Cell Division
  • Polymerase Chain Reaction
  • Receptors, LHRH
  • Aldosterone
  • Cancer RNA
Tag cloud generated 16 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (5)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: GNRHR (cancer-related)

Kishimoto R, Oki K, Yoneda M, et al.
Gonadotropin-Releasing Hormone Stimulate Aldosterone Production in a Subset of Aldosterone-Producing Adenoma.
Medicine (Baltimore). 2016; 95(20):e3659 [PubMed] Free Access to Full Article Related Publications
We aimed to detect novel genes associated with G protein-coupled receptors (GPCRs) in aldosterone-producing adenoma (APA) and elucidate the mechanisms underlying aldosterone production.Microarray analysis targeting GPCR-associated genes was conducted using APA without known mutations (APA-WT) samples (n = 3) and APA with the KCNJ5 mutation (APA-KCNJ5; n = 3). Since gonadotropin-releasing hormone receptor (GNRHR) was the highest expression in APA-WT by microarray analysis, we investigated the effect of gonadotropin-releasing hormone (GnRH) stimulation on aldosterone production.The quantitative polymerase chain reaction assay results revealed higher GNRHR expression levels in APA-WT samples those in APA-KCNJ5 samples (P < 0.05). LHCGR levels were also significantly elevated in APA-WT samples, and there was a significant and positive correlation between GNRHR and LHCGR expression in all APA samples (r = 0.476, P < 0.05). Patients with APA-WT (n = 9), which showed higher GNRHR and LHCGR levels, had significantly higher GnRH-stimulated aldosterone response than those with APA-KCNJ5 (n = 13) (P < 0.05). Multiple regression analysis revealed that the presence of the KCNJ5 mutation was linked to GNRHR mRNA expression (β = 0.94 and P < 0.01). HAC15 cells with KCNJ5 gene carrying T158A mutation exhibited a significantly lower GNRHR expression than that in control cells (P < 0.05).We clarified increased expression of GNRHR and LHCGR in APA-WT, and the molecular analysis including the receptor expression associated with clinical findings of GnRH stimulation.

Yun BS, Seong SJ, Cha DH, et al.
Changes in proliferating and apoptotic markers of leiomyoma following treatment with a selective progesterone receptor modulator or gonadotropin-releasing hormone agonist.
Eur J Obstet Gynecol Reprod Biol. 2015; 191:62-7 [PubMed] Related Publications
OBJECTIVE: To evaluate changes in proliferating and apoptotic markers of myoma tissue from patients treated with a selective progesterone receptor modulator (SPRM) or GnRH agonist by measuring expression of PDGF-A mRNA, IGF-1 mRNA, bcl-2 mRNA, and PCNA and caspase-3 protein.
STUDY DESIGN: Between December 2013 and July 2014, women with symptomatic leiomyoma were divided into control (no treatment before surgery), SPRM (treatment with ulipristal acetate [SPRM] for 3 months before surgery), and GnRHa (treatment with leuprolide acetate [GnRH agonist] for 3 months before surgery) groups. Tissue specimens were collected from the myoma core and normal myometrium of all patients. The expression of mRNA and protein was assessed by quantitative real-time reverse transcriptase-polymerase chain reaction and Western blot.
RESULTS: A total of 38 patients were enrolled (control group, n=14; SPRM group, n=13; GnRHa group, n=11). PDGF-A mRNA expression was lower in both the myoma core and normal myometrium tissues of the SPRM compared with the control group, but there was no difference between the control and GnRHa group. There were also no group differences in bcl-2 mRNA or IGF-1 mRNA expression. Both PCNA and caspase-3 protein expression were higher in the leiomyoma tissue of the SPRM compared with the control group, but there was no difference between the control and GnRHa groups in the expression of either protein.
CONCLUSION: Both proliferation and apoptosis were increased in the leiomyoma of patients after SPRM treatment, but there was no change following GnRH agonist treatment, in vivo. However, PDGF-A mRNA was decreased after SPRM treatment, indicating a dual effect of progesterone on the regulation of growth factors. Furthermore, there was an increase in caspase-3 protein, but not bcl-2 mRNA, expression in the SPRM group suggesting that SPRM may exert its effects in pathways other than the bcl-2 apoptotic pathway.

Vuletic I, Liu J, Wu H, et al.
Establishment of an mKate2-Expressing Cell Line for Non-Invasive Real-Time Breast Cancer In Vivo Imaging.
Mol Imaging Biol. 2015; 17(6):811-8 [PubMed] Related Publications
PURPOSE: Non-invasive real-time in vivo imaging experiments using mice as animal models have become crucial for understanding cancer development and treatment. In this study, we have developed and validated a new breast cancer cell line MDA-MB-435s that stably express a far-red fluorescence protein (mKate2) and that could serve as a highly valuable cell model for studying breast cancer detection and therapy using in vivo fluorescence imaging in nude mice.
PROCEDURES: The new cell line (MDA-MB-435s-mKate2) was constructed by plasmid transfection. The stability and sensitivity of mKate2, and the cell biological activities, were tested in vitro using different experimental approaches. For its potential use in tumor growth research and drug therapy in vivo, MDA-MB-435s-mKate2 was validated using the immunocompromised Balb/c nude mice tumor model. In addition, the new cell line has been characterized as a luteinizing hormone-releasing hormone receptor (LHRHR) positive cell line.
RESULTS: Firstly, MDA-MB-435s-mKate2 has shown a stable chromosomal integration of the amplified mKate2 gene and good fluorescence sensitivity for detection using a fluorescence reflectance imaging (FRI) device. Compared to its parental cell line, no significant difference in cell migration, proliferation, and clone formation was observed in vitro. Secondly, using the quantification of tumor-fluorescence surface area in live animals, we were able to monitor and detect the tumor progress or tumor inhibition rate (by Paclitaxel treatment) non-invasively and in real-time. Furthermore, MDA-MB-435s-mKate2 has been positively tested for LHRHR; these findings open the possibility to use this cell line for future studies of breast cancer therapy based on LHRH analogs in vivo.
CONCLUSION: In the present research, we have successfully built the MDA-MB-435s-mKate2 cell line that can be used as a suitable cell model for breast cancer therapy and anti-cancer drug evaluation by non-invasive fluorescence imaging in mice.

Nakamura Y, Hattangady NG, Ye P, et al.
Aberrant gonadotropin-releasing hormone receptor (GnRHR) expression and its regulation of CYP11B2 expression and aldosterone production in adrenal aldosterone-producing adenoma (APA).
Mol Cell Endocrinol. 2014; 384(1-2):102-8 [PubMed] Free Access to Full Article Related Publications
Aberrant expression of gonadotropin-releasing hormone receptor (GnRHR) has been reported in human adrenal tissues including aldosterone-producing adenoma (APA). However, the details of its expression and functional role in adrenals are still not clear. In this study, quantitative RT-PCR analysis revealed the mean level of GnRHR mRNA was significantly higher in APAs than in human normal adrenal (NA) (P=0.004). GnRHR protein expression was detected in human NA and neoplastic adrenal tissues. In H295R cells transfected with GnRHR, treatment with GnRH resulted in a concentration-dependent increase in CYP11B2 reporter activity. Chronic activation of GnRHR with GnRH (100nM), in a cell line with doxycycline-inducible GnRHR (H295R-TR/GnRHR), increased CYP11B2 expression and aldosterone production. These agonistic effects were inhibited by blockers for the calcium signaling pathway, KN93 and calmidazolium. These results suggest GnRH, through heterotopic expression of its receptor, may be a potential regulator of CYP11B2 expression levels in some cases of APA.

Garcia EA, Trivellin G, Aflorei ED, et al.
Characterization of SNARE proteins in human pituitary adenomas: targeted secretion inhibitors as a new strategy for the treatment of acromegaly?
J Clin Endocrinol Metab. 2013; 98(12):E1918-26 [PubMed] Related Publications
CONTEXT: Targeted secretion inhibitors (TSIs), a new class of recombinant biotherapeutic proteins engineered from botulinum toxin, represent a novel approach for treating diseases with excess secretion. They inhibit hormone secretion from targeted cell types through cleavage of SNARE (soluble N-ethylmaleimide-sensitive factor-activating protein receptor) proteins. qGHRH-LH(N)/D is a TSI targeting pituitary somatotroph through binding to the GHRH-receptor and cleavage of the vesicle-associated membrane protein (VAMP) family of SNARE proteins.
OBJECTIVE: Our objective was to study SNARE protein expression in pituitary adenomas and to inhibit GH secretion from somatotropinomas using qGHRH-LH(N)/D.
DESIGN: We analyzed human pituitary adenoma analysis for SNARE expression and response to qGHRH-LH(N)/D treatment.
SETTING: The study was conducted in University Hospitals.
PATIENTS: We used pituitary adenoma samples from 25 acromegaly and 47 nonfunctioning pituitary adenoma patients.
OUTCOME: Vesicle-SNARE (VAMP1-3), target-SNARE (syntaxin1, SNAP-23, and SNAP-25), and GHRH-receptor detection with RT-qPCR, immunocytochemistry, and immunoblotting. Assessment of TSI catalytic activity on VAMPs and release of GH from adenoma cells.
RESULTS: SNARE proteins were variably expressed in pituitary samples. In vitro evidence using recombinant GFP-VAMP2&3 or pituitary adenoma lysates suggested sufficient catalytic activity of qGHRH-LH(N)/D to degrade VAMPs, but was unable to inhibit GH secretion in somatotropinoma cell cultures.
CONCLUSIONS: SNARE proteins are present in human pituitary somatotroph adenomas that can be targeted by TSIs to inhibit GH secretion. qGHRH-LH(N)/D was unable to inhibit GH secretion from human somatotroph adenoma cells. Further studies are required to understand how the SNARE proteins drive GH secretion in human somatotrophs to allow the development of novel TSIs with a potential therapeutic benefit.

Thompson IR, Kaiser UB
GnRH pulse frequency-dependent differential regulation of LH and FSH gene expression.
Mol Cell Endocrinol. 2014; 385(1-2):28-35 [PubMed] Free Access to Full Article Related Publications
The pituitary gonadotropin hormones, FSH and LH, are essential for fertility. Containing an identical α-subunit (CGA), they are comprised of unique β-subunits, FSHβ and LHβ, respectively. These two hormones are regulated by the hypothalamic decapeptide, GnRH, which is released in a pulsatile manner from GnRH neurons located in the hypothalamus. Varying frequencies of pulsatile GnRH stimulate distinct signaling pathways and transcriptional machinery after binding to the receptor, GnRHR, on the cell surface of anterior pituitary gonadotropes. This ligand-receptor binding and activation orchestrates the synthesis and release of FSH and LH, in synergy with other effectors of gonadotropin production, such as activin, inhibin and steroids. Current research efforts aim to discover the mechanisms responsible for the decoding of the GnRH pulse signal by the gonadotrope. Modulating the response to GnRH has the potential to lead to new therapies for patients with altered gonadotropin secretion, such as those with hypothalamic amenorrhea or polycystic ovarian syndrome.

Wu HM, Wang HS, Huang HY, et al.
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.
BMC Cancer. 2013; 13:300 [PubMed] Free Access to Full Article Related Publications
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.
CONCLUSION: 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.

Cheng JC, Klausen C, Leung PC
Overexpression of wild-type but not C134W mutant FOXL2 enhances GnRH-induced cell apoptosis by increasing GnRH receptor expression in human granulosa cell tumors.
PLoS One. 2013; 8(1):e55099 [PubMed] Free Access to Full Article Related Publications
The etiology of granulosa cell tumors (GCTs) is largely unknown. The primary mode of treatment is surgical, however not all women are cured by surgery alone. Thus, it is important to develop improved treatments through a greater understanding of the molecular mechanisms that contribute to this disease. Recently, it has been shown that a FOXL2 402C>G (C134W) mutation is present in 97% of human adult-type GCTs, suggesting an important role for this mutation in the development of GCTs. We have shown previously that gonadotropin-releasing hormone (GnRH)-I and -II induce apoptosis in cultured normal human granulosa cells. Moreover, it has been reported that FOXL2 can bind to the promoter of the mouse GnRH receptor gene and regulate its transcription. Thus, we hypothesized that C134W mutant FOXL2 could modulate the pro-apoptotic effects of GnRH via aberrant regulation of GnRH receptor levels. Using KGN cells, a human GCT-derived cell line which harbors the FOXL2 402C>G mutation, we show that treatment with GnRH-I and -II induces cell apoptosis, and that small interfering RNA-mediated depletion of GnRH receptor abolishes these effects. Overexpression of wild-type FOXL2 increases both mRNA and protein levels of GnRH receptor and consequently enhances GnRH-induced apoptosis. Importantly, neither the expression levels of GnRH receptor nor GnRH-induced apoptosis were affected by overexpression of the C134W mutant FOXL2. Interestingly, knockdown of endogenous FOXL2 down-regulates GnRHR expression in normal human granulosa cells with wild-type FOXL2, but not in KGN cells. These results suggest that the FOXL2 402C>G mutation may contribute to the development of human adult-type GCTs by reducing the expression of GnRH receptor, thus conferring resistance to GnRH-induced cell apoptosis.

Pazaitou-Panayiotou K, Chemonidou C, Poupi A, et al.
Gonadotropin-releasing hormone neuropeptides and receptor in human breast cancer: correlation to poor prognosis parameters.
Peptides. 2013; 42:15-24 [PubMed] Related Publications
Expression of the two gonadotropin-releasing hormone homologue peptides GnRHI and GnRHII and their receptor GnRHR has been demonstrated in a number of malignancies. In hormone-dependent breast cancer, GnRH analogs are used for therapy in premenopausal women. Gene expression of GnRHI, II and R was studied in breast biopsies from primary breast adenocarcinoma obtained from the tumor and the adjacent benign tissue. Levels were evaluated by a multiplex real-time RT-PCR. GnRHI transcripts were detected in 14.7% of the benign and 29.4% malignant biopsies and GnRHII in 21.2% benign and 44.1% malignant biopsies. GnRHR was also more frequent in the malignant (54.2%) than in the benign (24.0%) biopsies, at similar expression levels. No transcripts were detected in biopsies from healthy individuals. There was a strong correlation between the presence of GnRHI and GnRHII transcripts and their receptor in the benign and the malignant biopsies. GnRHI, II and R expression correlated significantly with poor prognosis pathological parameters. Immunohistochemistry for GnRHR revealed expression in malignant cells and in epithelial cells of mammary ducts of the adjacent area with pre-cancerous features. In contrast, GnRH I and II peptides were rarely expressed at low levels in breast cancer cells. In conclusion GnRH peptides and receptor are expressed more frequently in breast tumors than in the adjacent mammary tissue, representing a malignant feature. Their expression correlated to tumor characteristics of poor prognosis and was therefore related to more aggressive malignancies. Concomitant expression of peptides and receptor supports an autocrine/paracrine regulating role.

Taniguchi F, Higaki H, Azuma Y, et al.
Gonadotropin-releasing hormone analogues reduce the proliferation of endometrial stromal cells but not endometriotic cells.
Gynecol Obstet Invest. 2013; 75(1):9-15 [PubMed] Related Publications
AIMS: We investigated the potential of gonadotropin-releasing hormone (GnRH) agonists and GnRH antagonists to inhibit cell proliferation in endometriotic and endometrial stromal cells.
METHODS: Twenty patients with ovarian endometriomas and 18 patients with uterine fibromas were recruited. Endometriotic and endometrial stromal cells were obtained from the ovarian chocolate cyst linings and the eutopic endometria of premenopausal women with uterine fibromas, respectively.
RESULTS: GnRH agonist or antagonist treatment attenuated tumor necrosis factor (TNF)-α-induced cell proliferation in the endometrial stromal cells, whereas endometriotic stromal cells did not respond to treatment. The endometriotic stromal cells exhibited a decreased expression of the type I GnRH receptor compared with the endometrial stromal cells. GnRH agonists or antagonists did not repress TNF-α-induced IL-8 production in endometriotic stromal cells.
CONCLUSION: GnRH agonists and antagonists have similar effects in slowing the growth of endometrial stromal cells. Endometriotic stromal cells resist the antiproliferative effect of GnRH agonists and antagonists.

Carlsson E, Krohn K, Ovaska K, et al.
Neuron navigator 3 alterations in nervous system tumors associate with tumor malignancy grade and prognosis.
Genes Chromosomes Cancer. 2013; 52(2):191-201 [PubMed] Related Publications
Copy number changes or reduced expression of the Neuron navigator 3 (NAV3) gene occurs in neuroblastomas and malignancies of epithelial or lymphoid origin. To elucidate whether NAV3 has a role in the tumorigenesis of nervous system tumors in general, we studied central and peripheral nervous system tumors for NAV3 copy number changes. In search for common tumorigenic denominators, we analyzed 113 central and peripheral nervous system tumors, including glial tumors (grades I-IV gliomas), medulloblastomas, and neuroblastomas. NAV3 copy number changes were studied by fluorescence in situ hybridization and correlated to survival analyses. To identify target genes of NAV3 deletion, NAV3 was silenced by siRNA in glioblastoma cell lines and gene expression profiles were analyzed by Agilent 4×44k dual-color microarrays. Selected upregulations were confirmed by immunohistochemistry and quantitative polymerase chain reaction. We found NAV3 amplifications to dominate in neuronally differentiated tumors, whereas glial tumors showed almost equal proportions of NAV3 deletion and amplification. However, Grade IV gliomas had more frequent NAV3 deletions than grades I-III gliomas. Silencing of NAV3 in glioma cell lines led to the upregulation of receptor genes associated with gonadotropin-releasing hormone and Jak-Stat signaling pathways. Kaplan-Meier analysis of the entire clinical tumor material showed association between NAV3 amplifications and favorable prognosis, as well as NAV3 deletions and unfavorable prognosis. With Cox regression model, a hazard ratio of 0.51 was observed for NAV3 amplifications and 1.36 for NAV3 deletions. We conclude that NAV3 may be a potential new prognostic biomarker and a potential therapeutic target.

Britten JL, Malik M, Levy G, et al.
Gonadotropin-releasing hormone (GnRH) agonist leuprolide acetate and GnRH antagonist cetrorelix acetate directly inhibit leiomyoma extracellular matrix production.
Fertil Steril. 2012; 98(5):1299-307 [PubMed] Related Publications
OBJECTIVE: To determine the direct effect that GnRH analogues leuprolide acetate and cetrorelix acetate have on extracellular matrix in human leiomyoma and patient-matched myometrial cells.
DESIGN: Laboratory study.
SETTING: University hospital.
INTERVENTION(S): Cell culture, proliferation studies, and messenger RNA and protein analysis.
MAIN OUTCOME MEASURE(S): Expression of GnRHR1, COL1A1, fibronectin, and versican variant V0 in treated leiomyoma cells and patient-matched myometrial cells.
RESULT(S): Leiomyoma cells were treated with GnRH analogues for 6, 24, and 120 hours. Leuprolide treatment for 6 hours resulted in an increase in expression of GnRHR1 (4.02 ± 0.12-fold), COL1A1 (6.41 ± 0.29-fold), fibronectin (9.69 ± 0.18-fold), and versican variant V0 (7.58 ± 0.43-fold). Leiomyoma cells treated with cetrorelix for 6 hours showed a decreased expression of GnRHR1 (0.5 ± 0.15-fold), COL1A1 (3.79 ± 0.7-fold), fibronectin (0.92 ± 0.09-fold), and versican variant V0 (0.14 ± 0.07-fold). Leuprolide treatment of leiomyoma cells at high concentrations (10(-5) M) did not result in an increase in protein production. Cetrorelix treatment of leiomyoma cells for 6 hours showed an increase in fibronectin protein production (3.14 ± 0.09-fold). Protein production of leiomyoma cells treated with cetrorelix for 120 hours demonstrated a decrease in GnRHR1 (0.51 ± 0.07-fold), COL1A1 (0.35 ± 0.07-fold), fibronectin (1.94 ± 0.08-fold), and versican variant V0 (0.77 ± 0.19-fold).
CONCLUSION(S): Our findings demonstrate that GnRH analogue treatment directly regulated COL1A1, fibronectin, and matrix proteoglycan production. The reduction in versican variant V0 gene expression caused by cetrorelix treatment, and its association with the osmotic regulation of leiomyomas, presents a new and innovative approach to therapy for this disease.

Lattrich C, Müller AK, Schüler S, et al.
Single nucleotide polymorphisms in the regulatory region of gonadotropin-releasing hormone receptor gene and breast cancer susceptibility.
Oncol Rep. 2012; 28(3):1091-5 [PubMed] Related Publications
It is known that exposure to estrogens affects the pathophysiology of breast cancer. The key role of gonadotropin-releasing hormone (GnRH) in the regulation of female steroid hormone metabolism raises the question of whether polymorphisms in its receptor, GnRHR, might influence breast cancer risk. To test this hypothesis, we analyzed three single nucleotide polymorphisms (SNPs) in the 5'-regulatory region of the GnRHR gene in a total of 565 women, 254 women with breast cancer and 311 women without any malignancy by allele-specific PCR. No significant differences were observed between the breast cancer and control group in terms of genotype, allele frequency or allele positivity. In contrast, different frequencies of the SNPs rs13138607, rs12644822 and rs3756159 were observed after sub-grouping the breast cancer cases according to tumor grading. Our data suggest a potential role of GnRHR gene polymorphisms in the development of breast cancer.

Carlsson E, Ranki A, Sipilä L, et al.
Potential role of a navigator gene NAV3 in colorectal cancer.
Br J Cancer. 2012; 106(3):517-24 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The recently described navigator proteins have a multifaceted role in cytoskeletal dynamics. We report here on the relevance of one of them, navigator 3 (NAV3), in colorectal cancer (CRC).
METHODS: We analysed changes in chromosome 12 and NAV3 copy number in CRC/adenoma samples of 59 patients and in 6 CRC cell lines, using fluorescence in situ hybridisation, loss of heterozygosity, and array-CGH. NAV3 target genes were identified by siRNA depletion, expression arrays, and immunohistochemistry.
RESULTS: NAV3 deletion and chromosome 12 polysomy were detected in 30 and 70% of microsatellite stability (MSS) carcinomas, in 23 and 30% of adenomas and in four of six CRC cell lines. NAV3 amplification was found in 25% of MSS samples. NAV3 alterations correlated with lymph node metastasis. In normal colon cells, NAV3 silencing induced upregulation of interleukin 23 receptor (IL23R) and gonadotropin releasing hormone receptor. In MSS and microsatellite instability tumours, IL23R immunoreactivity correlated with Dukes' staging and lymph node metastases, whereas nuclear beta-catenin correlated with lymph node metastases only.
CONCLUSION: NAV3 copy number changes are frequent in CRC and in adenomas, and upregulation of IL23R, following NAV3 silencing, strongly correlates with Dukes' staging and lymph node metastases. This suggests that NAV3 has a role in linking tissue inflammation to cancer development in the colon.

Ko YH, Ha YR, Kim JW, et al.
Silencing of the GnRH type 1 receptor blocks the antiproliferative effect of the GnRH agonist, leuprolide, on the androgen-independent prostate cancer cell line DU145.
J Int Med Res. 2011; 39(3):729-39 [PubMed] Related Publications
This study investigated the mechanism of action of a gonadotropin-releasing hormone (GnRH) agonist, leuprolide, on proliferation of the hormone-refractory prostate cancer cell line DU145, transfected with short hairpin RNA (shRNA), to reduce expression of the GNRHR1 gene (which encodes the GnRH type 1 receptor). DU145 cell proliferation in the presence of leuprolide (10(-9) and 10(-7) M) or control medium was measured before and after GnRHR1 knockdown. Reverse transcription-polymerase chain reaction and Western blot analysis were used to measure the degree of GNRHR1 silencing. DU145 cells treated with leuprolide (10(-9) and 10(-7) M) showed significant growth inhibition compared with control-treated DU145 cells. Transfection with GNRHR1 -shRNA significantly decreased GNRHR1 expression at 48 h. DU145 cells transfected with silencing GNRHR1 -shRNA showed normal growth patterns; however, there was no significant inhibition of proliferation of DU145 cells transfected with GNRHR1 -shRNA compared with cells transfected with control-shRNA in response to leuprolide. These data demonstrated that the antiproliferative effect of leuprolide was mediated by the GnRHR1.

Li Q, Yang G, Wang Y, et al.
Common genetic variation in the 3'-untranslated region of gonadotropin-releasing hormone receptor regulates gene expression in cella and is associated with thyroid function, insulin secretion as well as insulin sensitivity in polycystic ovary syndrome patients.
Hum Genet. 2011; 129(5):553-61 [PubMed] Related Publications
Gonadotropin-releasing hormone receptor (GNRHR) is a member of the G protein-coupled Ca(2+)-dependent family of receptors. It interacts with GnRH, whose signaling plays an important role in thyroid-stimulating hormone (TSH) secretion and insulin activity. There has been no study on the genetic effect of GNRHR on TSH secretion and insulin action in polycystic ovary syndrome (PCOS). We decided to investigate whether naturally occurring genetic variation at the human GNRHR locus is associated with thyroid function, insulin secretion and insulin sensitivity in PCOS. We undertook a systematic search for polymorphisms in GNRHR by resequencing the gene and then genotyped common single-nucleotide polymorphisms across the locus in 261 PCOS patients well-phenotyped for several metabolic traits to determine associations. A test for association of common genetic variants with susceptibility to PCOS was carried out in a large cohort of 948 subjects. Finally, we experimentally validated the marker-on-trait associations using GNRHR 3'-UTR region/reporter analysis in 293T cells. The 3'-UTR variant rs1038426 was associated with serum thyroid concentration (P = 0.007), change of insulin levels during oral glucose tolerance test (P = 0.004) and insulin sensitivity index (P = 0.014). In a functional study, 3'-UTR variant T allele increased reporter expression by a transfected luciferase reporter/GNRHR 3'-UTR expression plasmid. In conclusion, our results strongly suggest that common genetic variant in GNRHR contributes to the phenotypic expression of PCOS. The findings suggest novel pathophysiological links between the GNRHR locus and thyroid function and insulin secretion in PCOS.

Poon SL, Klausen C, Hammond GL, Leung PC
37-kDa laminin receptor precursor mediates GnRH-II-induced MMP-2 expression and invasiveness in ovarian cancer cells.
Mol Endocrinol. 2011; 25(2):327-38 [PubMed] Related Publications
GnRH-II enhances ovarian cancer cell invasion in an autocrine manner. We have now found that GnRH-II increases 37-kDa laminin receptor precursor (LRP) production in GnRH receptor (GnRHR)-positive OVCAR-3 and CaOV-3 ovarian cancer cells, while small interfering RNA (siRNA)-mediated depletion of GnRH-II or GnRHR mRNA abrogates this. The invasiveness of ovarian cancer cells is also reduced >85% by siRNA-mediated knockdown of LRP levels and >50% by pretreatment of Matrigel with a synthetic peptide that blocks interactions between laminin and the 67-kDa nonintegrin laminin receptor which comprises two LRP subunits. Conversely, overexpressing LRP in CaOV-3 cells increases their invasiveness 5-fold, while overexpressing LRP with a nonfunctional laminin-binding site does not. Depletion of LRP by siRNA treatment reduces CaOV-3 cell attachment to laminin-coated plates by ∼80% but only reduces their binding to Matrigel by ∼20%. Thus, while LRP influences CaOV-3 cell adhesion to laminin, LRP must act in other ways to enhance invasion. Matrix metalloproteinases (MMPs) are key mediators of invasion, and LRP siRNA treatment of OVCAR-3 and CaOV-3 cells inhibits MMP-2 but not MMP-9 mRNA levels. Overexpressing LRP in these cells increases MMP-2 production specifically, while a laminin-binding deficient LRP does not. Importantly, LRP siRNA treatment abolishes GnRH-II-induced MMP-2 production, and invasion in OVCAR-3 and CaOV-3 cells, which was also seen after MMP-2 siRNA treatment. These results suggest that GnRH-II-induced LRP expression increases the amount of the 67-kDa nonintegrin laminin receptor, which appears to interact with laminin in the extracellular matrix to promote MMP-2 expression and enhance ovarian cancer cell invasion.

Wen J, Feng Y, Bjorklund CC, et al.
Luteinizing Hormone-Releasing Hormone (LHRH)-I antagonist cetrorelix inhibits myeloma cell growth in vitro and in vivo.
Mol Cancer Ther. 2011; 10(1):148-58 [PubMed] Related Publications
The objective of this study was to determine the effects of an luteinizing hormone-releasing hormone (LHRH)-I antagonist, Cetrorelix, on human multiple myeloma (MM) cells and to elucidate the mechanisms of action. We showed that LHRH-I and LHRHR-I genes were expressed in MM cell lines and primary MM cells. Treatment with Cetrorelix inhibited growth and colony-forming ability of myeloma cells, including cell lines resistant to arsenic trioxide, bortezomib, or lenalidomide. Cetrorelix induced apoptosis in myeloma cells including primary myeloma cells. In addition, Cetrorelix inhibited the growth of human myeloma cells xenografted into mice without any apparent side effects. Cetrorelix downregulated the nuclear factor-kappa B (NF-κB) pathway activity and the expression of cytokines, including interleukin 6, insulin-like growth factor 1, VEGF-A, and stromal-derived factor 1, important for myeloma cell growth and survival in myeloma cells and/or marrow stromal cells from myeloma patients. Cetrorelix decreased the phosphorylation of extracellular signal regulated kinase 1/2 and STAT3 in myeloma cells, two crucial pathways for myeloma cells growth and survival. Moreover, the expression of p21 and p53 was increased, whereas that of antiapoptotic proteins Bcl-2 and Bcl-x(L) was reduced by Cetrorelix. Our findings indicate that Cetrorelix induces cytotoxicity in myeloma cells through various mechanisms and provide a rationale for investigating Cetrorelix for the treatment of MM.

Khan KN, Kitajima M, Hiraki K, et al.
Cell proliferation effect of GnRH agonist on pathological lesions of women with endometriosis, adenomyosis and uterine myoma.
Hum Reprod. 2010; 25(11):2878-90 [PubMed] Related Publications
BACKGROUND: We recently demonstrated the effect of gonadotrophin-releasing hormone agonist (GnRHa) on tissue inflammation, angiogenesis and apoptosis in endometriosis, adenomyosis and uterine myoma. Here, we investigated expression of GnRH receptors (GnRHRs) and effect of GnRHa on the proliferation of cells derived from endometria and pathological lesions of women with these reproductive diseases.
METHODS: Biopsy specimens were collected from lesions and corresponding endometria of 35 women with pelvic endometriosis, 45 women with ovarian endometrioma, 35 women with adenomyosis and 56 women with uterine myoma during laparoscopy or laparotomy. The gene and protein expressions of GnRHR in eutopic/ectopic cells and tissues were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry. The immunoreactivity of GnRHR in tissue was analysed by quantitative-histogram (Q-H) scores. The exogenous effect of GnRHa on cell proliferation was examined by 5-bromo-2-deoxyuridine incorporation assay. The Ki-67-immunoreactive cell proliferation index was analysed in biopsy specimens derived from GnRHa-treated and -non-treated women.
RESULTS: Types I and II GnRHRs mRNA and proteins were expressed in eutopic endometria and pathological lesions derived from women with endometriosis, adenomyosis and uterine myoma. GnRHR expression was the highest in the menstrual phase when compared with other phases of the menstrual cycle. Higher Q-H scores of GnRHR immunoreaction were found in blood-filled opaque red lesions than in other peritoneal lesions. Exogenous treatment with GnRHa significantly suppressed the proliferation of cells derived from respective endometria and pathological lesions when compared with GnRHa-non-treated cells.
CONCLUSIONS: Local tissue expression of GnRHR was detected in endometriosis, adenomyosis and uterine myoma. In addition to a hypo-estrogenic effect, a direct anti-proliferative effect of GnRHa may be involved in the regression of these reproductive diseases with consequent remission of clinical symptoms.

Chan YM, Fenoglio-Simeone KA, Paraschos S, et al.
Central precocious puberty due to hypothalamic hamartomas correlates with anatomic features but not with expression of GnRH, TGFalpha, or KISS1.
Horm Res Paediatr. 2010; 73(5):312-9 [PubMed] Free Access to Full Article Related Publications
BACKGROUND/AIMS: Hypothalamic hamartomas are the most common identifiable cause of central precocious puberty (CPP). Hamartoma characteristics proposed to be associated with CPP include specific anatomic features and expression of molecules such as gonadotropin-releasing hormone (GnRH), transforming growth factor alpha (TGFalpha), and GRM1A, which encodes the type 1 metabotropic glutamate receptor alpha isoform. We sought to determine whether hamartomas that cause CPP could be distinguished by anatomic features, expression of these molecules, or expression of KISS1, whose products signal through the receptor GPR54 to stimulate GnRH release.
METHODS: Clinical records and radiologic images were reviewed for 18 patients who underwent hamartoma resection for intractable seizures; 7 had precocious puberty. Resected tissue was examined for expression of GnRH, GnRH receptor (GnRHR), TGFalpha, KISS1, GPR54, and GRM1A.
RESULTS: Hypothalamic hamartomas associated with CPP were more likely to contact the infundibulum or tuber cinereum and were larger than hamartomas not associated with CPP. GnRH, TGFalpha, and GnRHR were expressed by all hamartomas studied. Expression of KISS1, GPR54, and GRM1A did not differ significantly between hamartomas associated and not associated with CPP.
CONCLUSION: Anatomic features rather than expression patterns of candidate molecules distinguish hypothalamic hamartomas that are associated with CPP from those that are not.

Canzian F, Kaaks R, Cox DG, et al.
Genetic polymorphisms of the GNRH1 and GNRHR genes and risk of breast cancer in the National Cancer Institute Breast and Prostate Cancer Cohort Consortium (BPC3).
BMC Cancer. 2009; 9:257 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Gonadotropin releasing hormone (GNRH1) triggers the release of follicle stimulating hormone and luteinizing hormone from the pituitary. Genetic variants in the gene encoding GNRH1 or its receptor may influence breast cancer risk by modulating production of ovarian steroid hormones. We studied the association between breast cancer risk and polymorphisms in genes that code for GNRH1 and its receptor (GNRHR) in the large National Cancer Institute Breast and Prostate Cancer Cohort Consortium (NCI-BPC3).
METHODS: We sequenced exons of GNRH1 and GNRHR in 95 invasive breast cancer cases. Resulting single nucleotide polymorphisms (SNPs) were genotyped and used to identify haplotype-tagging SNPs (htSNPS) in a panel of 349 healthy women. The htSNPs were genotyped in 5,603 invasive breast cancer cases and 7,480 controls from the Cancer Prevention Study-II (CPS-II), European Prospective Investigation on Cancer and Nutrition (EPIC), Multiethnic Cohort (MEC), Nurses' Health Study (NHS), and Women's Health Study (WHS). Circulating levels of sex steroids (androstenedione, estradiol, estrone and testosterone) were also measured in 4713 study subjects.
RESULTS: Breast cancer risk was not associated with any polymorphism or haplotype in the GNRH1 and GNRHR genes, nor were there any statistically significant interactions with known breast cancer risk factors. Polymorphisms in these two genes were not strongly associated with circulating hormone levels.
CONCLUSION: Common variants of the GNRH1 and GNRHR genes are not associated with risk of invasive breast cancer in Caucasians.

Fister S, Günthert AR, Aicher B, et al.
GnRH-II antagonists induce apoptosis in human endometrial, ovarian, and breast cancer cells via activation of stress-induced MAPKs p38 and JNK and proapoptotic protein Bax.
Cancer Res. 2009; 69(16):6473-81 [PubMed] Related Publications
Recently, we could show that gonadotropin-releasing hormone (GnRH)-II antagonists induce apoptosis in human endometrial, ovarian, and breast cancer cells in vitro and in vivo. In the present study, we have ascertained receptor binding and effects of GnRH-II antagonists on mitogenic signal transduction and on activation of proapoptotic protein Bax. The GnRH-II antagonists tested showed EC50 values for GnRH-I receptor binding in the range of 1 to 2 nmol/L. The GnRH-II agonist [D-Lys6]GnRH-II showed an EC50 value for GnRH-I receptor binding of approximately 1,000 nmol/L. Agonistic activity on GnRH-I receptor function with an EC50 of 13 nmol/L has been determined for [D-Lys6]GnRH-II. Antagonistic activities with EC50 values in the range of 1 nmol/L were determined for the GnRH-II antagonists. Treatment of human endometrial, ovarian, and breast cancer cells with GnRH-II antagonists resulted in time-dependent activation of stress-induced mitogen-activated protein kinases p38 and c-Jun NH2-terminal kinase. In addition, treatment with GnRH-II antagonists induced time-dependent activation of proapoptotic protein Bax. GnRH-II antagonists are not involved in activation of protein kinase B/Akt or extracellular signal-regulated kinase 1/2. The GnRH-II antagonists tested had similar binding affinities to the GnRH-I receptor comparable with that of GnRH-I antagonist Cetrorelix. Referring to the cyclic AMP response element reporter gene activation assay, the GnRH-II agonist [D-Lys6]GnRH-II has to be classified as an agonist at the GnRH-I receptor, whereas the GnRH-II antagonists tested are clear antagonists at the GnRH-I receptor. GnRH-II antagonists induce apoptotic cell death in human endometrial, ovarian, and breast cancer cells via activation of stress-induced mitogen-activated protein kinases p38 and c-Jun NH2-terminal kinase followed by activation of proapoptotic protein Bax.

Poon SL, Hammond GT, Leung PC
Epidermal growth factor-induced GnRH-II synthesis contributes to ovarian cancer cell invasion.
Mol Endocrinol. 2009; 23(10):1646-56 [PubMed] Related Publications
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.

Angelucci C, Lama G, Iacopino F, et al.
GnRH receptor expression in human prostate cancer cells is affected by hormones and growth factors.
Endocrine. 2009; 36(1):87-97 [PubMed] Related Publications
GnRH receptors (GnRH-R) have been found in various malignancies, including prostate cancer (PCa). They mediate the direct antitumor effects of GnRH analogs. Nevertheless, few reports concern drug-induced modulation of GnRH-R levels. In this study, we investigated GnRH-R expression in androgen-sensitive (LNCaP) and -insensitive (PC-3) PCa cells treated for 4 and 6 days with a GnRH agonist (Leuprorelin acetate, LA, 10(-11) or 10(-6) M), Dihydrotestosterone (DHT, 10(-9) M), Cyproterone acetate (CA, 10(-7) M), and Epidermal growth factor (EGF, 10 ng/ml), either alone or combined. The RT-PCR analysis showed no variation in GnRH-R mRNA levels of both treated LNCaP and PC-3 cells. On the contrary, immunoblotting indicated that in LNCaP and PC-3 cells, LA upregulated membrane GnRH-R expression (up to 92%). In androgen-sensitive cells, DHT induced a GnRH-R increase (up to 119%) always comparable to that occurring in the presence of CA. GnRH-R upregulation by LA/DHT or CA/DHT association was similar to that promoted by the single agents. In PC-3 cells, EGF upregulated GnRH-R (up to 110%). A prolonged treatment (for 12 days) determined a greater EGF-induced increase in GnRH-R levels (142%). Lower (or no) receptor enhancement occurred when LA and EGF were associated. Our findings indicate that LA post-transcriptionally upregulates its own membrane receptor in androgen-sensitive and -insensitive PCa cells, counteracting the receptor enhancement produced by DHT and EGF. The effects, obtained with a relatively long and continuous treatment, may have implications in the choice of therapy modality with GnRH analogs and may render the receptor a novel therapeutic target, particularly in hormone-refractory PCa.

Montagnani Marelli M, Moretti RM, Mai S, et al.
Type I gonadotropin-releasing hormone receptor mediates the antiproliferative effects of GnRH-II on prostate cancer cells.
J Clin Endocrinol Metab. 2009; 94(5):1761-7 [PubMed] Related Publications
BACKGROUND: GnRH-II has been shown to exert a strong antiproliferative action on tumors of the female reproductive system. The data so far reported on the effects of GnRH-II on prostate cancer growth are controversial. Moreover, it is still unclear through which receptor [type I or type II GnRH-receptor (GnRH-R)] GnRH-II might modulate cancer cell proliferation.
OBJECTIVE: The objective of this work was to investigate whether GnRH-II might affect the proliferation of prostate cancer cells and to identify the GnRH-R through which the peptide might exert its activity.
DESIGN: We investigated the effects of GnRH-II on prostate cancer cell proliferation. We then transfected PC3 cells with a small interfering RNA targeted to type I GnRH-R. After receptor silencing we evaluated the effects of GnRH-II on cell proliferation and on forskolin-induced intracellular cAMP accumulation. Similar experiments were performed by silencing type II GnRH-R.
RESULTS: GnRH-II exerted an antiproliferative activity on prostate cancer cells. Transfection of PC3 cells with a type I GnRH-R small interfering RNA resulted in a significant decrease of the expression of this receptor. After type I GnRH-R silencing: 1) the antiproliferative effect of GnRH-II was completely abrogated; and 2) GnRH-II lost its capacity to counteract the forskolin-induced cAMP accumulation. On the contrary, type II GnRH-R silencing did not counteract the antiproliferative effect of GnRH-II.
CONCLUSIONS: GnRH-II exerts a specific and significant antiproliferative action on prostate cancer cells. This antitumor effect is mediated by the activation of type I (but not of type II) GnRH-R and by its coupled cAMP intracellular signaling pathway.

Eicke N, Günthert AR, Emons G, Gründker C
GnRH-II agonist [D-Lys6]GnRH-II inhibits the EGF-induced mitogenic signal transduction in human endometrial and ovarian cancer cells.
Int J Oncol. 2006; 29(5):1223-9 [PubMed] Related Publications
The majority of human endometrial and ovarian cancers express receptors for GnRH type I (GnRH-I). Their proliferation is time- and dose-dependently reduced by GnRH-I and its analogs. GnRH-I analogs activate a phosphotyrosine-phosphatase (PTP) and inhibit EGF-induced mitogenic signal transduction. Recently we found that GnRH type II (GnRH-II) and its agonist [D-Lys6]GnRH-II also have antiproliferative effects on these tumor cells which are significantly greater than those of GnRH-I agonists. In a more recent study, we showed that the antiproliferative activity of GnRH-II on human endometrial and ovarian cancer cell lines is not mediated through the GnRH-I receptor. The underlying signal transduction mechanisms of GnRH-II are still unknown. In this study we showed that the mitogenic effects of growth factors in endometrial and ovarian cancer cell lines were counteracted by GnRH-II agonist [D-Lys6]GnRH-II, indicating an interaction with the mitogenic signal transduction. We showed that [D-Lys6]GnRH-II reduces EGF-induced auto-tyrosine-phosphorylation of EGF-receptors via activation of a PTP and that EGF-induced activation of mitogen-activated protein kinase was blocked in cells treated with [D-Lys6]GnRH-II. Furthermore, EGF-induced expression of the immediate early gene c-fos was inhibited by treatment with [D-Lys6]GnRH-II. After knock-out of GnRH-I receptor expression, GnRH-II agonist [D-Lys6]GnRH-II still activated PTP and inhibited the EGF-induced mitogenic signal transduction. These data indicate, that the effects of GnRH-II are not due to a cross-reaction with the GnRH-I receptor. In conclusion these data suggest that the signaling of GnRH-II agonist [D-Lys6]GnRH-II is comparable to that of GnRH-I analogs.

Choi JH, Choi KC, Auersperg N, Leung PC
Differential regulation of two forms of gonadotropin-releasing hormone messenger ribonucleic acid by gonadotropins in human immortalized ovarian surface epithelium and ovarian cancer cells.
Endocr Relat Cancer. 2006; 13(2):641-51 [PubMed] Related Publications
Although gonadotropin-releasing hormone (GnRH) has been shown to play a role as an autocrine/ paracrine regulator of cell growth in ovarian surface epithelium and ovarian cancer, the factors which regulate the expression of GnRH and its receptor in these cells are not well characterized. In the present study, we employed real-time PCR to determine the potential regulatory effect of gonadotropins on the expression levels of GnRH I (the mammalian GnRH), GnRH II (a second form of GnRH) and their common receptor (GnRHR) in immortalized ovarian surface epithelial (IOSE-80 and IOSE-80PC) cells and ovarian cancer cell lines (A2780, BG-1, CaOV-3, OVCAR-3 and SKOV-3). The cells were treated with increasing concentrations (100 and 1000 ng/ml) of recombinant follicle-stimulating hormone (FSH) or luteinizing hormone (LH) for 24 h. Treatment with FSH or LH reduced GnRH II mRNA levels in both IOSE cell lines and in three out of five ovarian cancer cell lines (A2780, BG-1 and OVCAR-3). A significant decrease in GnRHR mRNA levels was observed in IOSE and ovarian cancer cells, except CaOV-3 cells, following treatment with FSH or LH. In contrast, treatment with either FSH or LH had no effect on GnRH I mRNA levels in these cells, suggesting that gonadotropins regulate the two forms of GnRH and its receptor differentially. In separate experiments, the effect of gonadotropins on the anti-proliferative action of GnRH I and GnRH II agonists in IOSE-80, OVCAR-3 and SKOV-3 cells was investigated. The cells were pretreated with FSH or LH (100 ng/ml) for 24 h after which they were treated with either GnRH I or GnRH II (100 ng/ml) for 2 days, and cell growth was assessed by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide] assay. Pretreatment of the cells with FSH or LH significantly reversed the growth inhibitory effect of GnRH I and GnRH II agonists in these cell types. These results provide the first demonstration of a potential interaction between gonadotropins and the GnRH system in the growth regulation of normal ovarian surface epithelium and its neoplastic counterparts.

Kim KY, Choi KC, Auersperg N, Leung PC
Mechanism of gonadotropin-releasing hormone (GnRH)-I and -II-induced cell growth inhibition in ovarian cancer cells: role of the GnRH-I receptor and protein kinase C pathway.
Endocr Relat Cancer. 2006; 13(1):211-20 [PubMed] Related Publications
In our previous studies, we demonstrated that ERK1/2 (extracellular signal-regulated protein kinase) and p38 MAPK (mitogen-activated protein kinase) are required for gonadotropin-releasing hormone (GnRH)-II-induced anti-proliferation of ovarian cancer cells. In the present study, we examined the role of the GnRH-I receptor, as well as the activation of protein kinase C (PKC), in the anti-proliferative effect induced by GnRH-I or II in ovarian cancer cells. Our results demonstrated that Antide, a GnRH-I antagonist, reversed the activation of ERK1/2 induced by GnRH-I or II and abolished the anti-proliferative effect of GnRH-I and II in ovarian cancer cells. Transfection of short-interfering RNA to abrogate the gene expression of the GnRH-I receptor reversed GnRH-I and II-induced anti-proliferation. These results indicate that GnRH-I or II induce anti-proliferation through the GnRH-I receptor in ovarian cancer cells. In addition, the activation of ERK1/2 by GnRH-I or II was mimicked by phorbol-12-myristate 13-acetate, a PKC activator. Pretreatment with GF109203X, an inhibitor of PKC, blocked GnRH-induced ERK1/2 activation and anti-proliferation. These results suggest that the activation of PKC is responsible for GnRH-induced ERK1/2 activation and anti-proliferation in ovarian cancer cells. Taken together, these results indicate that binding of GnRH-I and II to the GnRH-I receptor activates ERK1/2 through a PKC-dependent pathway and is essential for GnRH-induced anti-proliferation of ovarian cancer cells.

Yeung CM, An BS, Cheng CK, et al.
Expression and transcriptional regulation of the GnRH receptor gene in human neuronal cells.
Mol Hum Reprod. 2005; 11(11):837-42 [PubMed] Related Publications
GnRH, acts via the GnRH receptor (GnRHR), plays a pivotal role in human reproduction by stimulating the synthesis and secretion of gonadotropins from pituitary gonadotropes. Studies have also suggested that it has other extra-pituitary functions. To date, the transcriptional regulation of human GnRHR gene in the brain remains largely unknown. Recently, the human cerebellar medulloblastoma cell line TE-671 is found to express GnRH. We report here for the first time that GnRHR is also expressed in this neuronal cell line. Treatment with GnRHR agonist stimulated the phosphorylation of both ERK1/2 and JNK in the cells. Moreover, transient transfection of various human GnRHR promoter-luciferase constructs into the cells identified an upstream promoter region located between -2197 and -1018. Important cis-acting regulatory elements were found at -1300/-1018 and -2197/- 1900, as deletion of either region caused a dramatic decrease in the promoter activity. An upstream GnRHR promoter element was identified to be important for basal transcription in the human neuronal TE-671 cells, in contrast to the previous finding that a downstream promoter is responsible for the gonadotrope-specific expression. Furthermore, we showed that antide (GnRHR antagonist) significantly stimulated the GnRHR promoter activity and inhibition of protein kinase C (PKC) pathway by staurosporine could also up-regulate the promoter activity in dose- and time-dependent manners. Taken together, these data suggest that activation of the GnRHR by interacting with GnRH may transcriptionally down-regulate itself via the PKC pathway in human neuronal cells.

Bolu SE, Tasar M, Uçkaya G, et al.
Increased abnormal pituitary findings on magnetic resonance in patients with male idiopathic hypogonadotrophic hypogonadism.
J Endocrinol Invest. 2004; 27(11):1029-33 [PubMed] Related Publications
Idiopathic hypogonadotropic hypogonadism (IHH) is a well-known disorder apart from its pathogenesis, which is still mostly unclear, even though a diverse subgroup of patients with hypogonadotropic hypogonadism and hyposmia/anosmia--the Kallman syndrome--have been partly linked to a mutated gene, known as kal-1 gene. In this study, we aimed to evaluate the sellar region of patients with IHH on magnetic resonance (MR). Pituitary MR of 120 male patients with IHH, diagnosed by a thorough endocrinologic assessment, were compared with pituitary MR of 49 healthy cases selected randomly who underwent detailed endocrinologic and neurologic evaluation and were assessed as healthy. Patients with IHH were diagnosed with microadenomas and irregularly contrasting pituitary (ICP), 18.2 and 10.7%, respectively. Although some anatomic variations were seen in healthy controls, microadenomas and ICP had solely been observed in patients with IHH and none in controls. Intact appearence of hypophysis in patients with IHH was significantly lower than in randomly selected healthy male subjects (p = 0.021). Mean infundibulum width of hypophysis and transverse diameter of posterior hypophysis were significantly broader in patients with IHH than in controls (both having p < 0.001), while mean hypophysis height and volume did not differ between groups. Results showed unusual incidence of pituitary abnormalities on pituitary MR in male patients with IHH. In conclusion, MR imaging is particularly useful in defining the morphological aspects of the hypothalamo - pituitary region in some endocrine disorders and other researchers might want to bear our findings in mind when performing MR evaluation of similar patient subgroups.

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