Expression of gonadotropin-releasing hormone II (GnRH-II) receptor in human endometrial and ovarian cancer cells and effects of GnRH-II on tumor cell proliferation

Role of gonadotropin-releasing hormone 2 and its receptor in human reproductive cancers

Gonadotropin-releasing hormone (GnRH1) and its receptor (GnRHR1) drive reproduction by regulating gonadotropins. Another form, GnRH2, and its receptor (GnRHR2), also exist in mammals. In humans, GnRH2 and GnRHR2 genes are present, but coding errors in the GnRHR2 gene are predicted to hinder full-length protein production. Nonetheless, mounting evidence supports the presence of a functional GnRHR2 in humans. GnRH2 and its receptor have been identified throughout the body, including peripheral reproductive tissues like the ovary, uterus, breast, and prostate. In addition, GnRH2 and its receptor have been detected in a wide number of reproductive cancer cells in humans. Notably, GnRH2 analogues have potent anti-proliferative, pro-apoptotic, and/or anti-metastatic effects on various reproductive cancers, including endometrial, breast, placental, ovarian, and prostate. Thus, GnRH2 is an emerging target to treat human reproductive cancers.

Comprehensive analysis of oxidative stress-related lncRNA signatures in glioma reveals the discrepancy of prognostic and immune infiltration

Oxidative stress refers to the process of reactive oxide species (ROS) increase in human body due to various factors, which leads to oxidative damage in human tissues. Current studies have confirmed that sustained oxidative stress is one of the distinctive features throughout the development of tumors. Numerous reports have shown that lncRNAs can regulate the process of oxidative stress through multiple pathways. However, the relationship between glioma-associated oxidative stress and lncRNAs is not clearly investigated. RNA sequencing data of GBM (glioblastoma) and LGG (low grade glioma) and corresponding clinical data were retrieved from the TCGA database. Oxidative stress related lncRNAs (ORLs) were identified by Pearson correlation analysis. Prognostic models for 6-ORLs were structured in the training cohort by univariate Cox regression analysis, multivariate Cox regression analysis and LASSO regression analysis. We constructed the nomogram and verified its predictive efficacy by Calibration curves and DCA decision curves. The biological functions and pathways of 6-ORLs-related mRNAs were inferred by Gene Set Enrichment Analysis. Immune cell abundance and immune function associated with risk score (RS) were estimated by ssGSEA, CIBERSORT and MCPcounter synthetically. External validation of the signature was completed using the CGGA-325 and CGGA-693 datasets. 6-ORLs signature-AC083864.2, AC107294.1, AL035446.1, CRNDE, LINC02600, and SNAI3-AS1-were identified through our analysis as being predictive of glioma prognosis. Kaplan-Meier and ROC curves indicated that the signature has a dependable predictive efficacy in the TCGA training cohort, validation cohort and CGGA-325/CGGA-693 test cohort. The 6-ORLs signature were verified to be independent prognostic predictors by multivariate cox regression and stratified survival analysis. Nomogram built with risk scores had strong predictive efficacy for patients' overall survival (OS). The outcomes of the functional enrichment analysis revealing potential molecular regulatory mechanisms for the 6-ORLs. Patients in the high-risk subgroup presented a significant immune microenvironment of macrophage M0 and cancer-associated fibroblast infiltration which was associated with a poorer prognosis. Finally, the expression levels of 6-ORLs in U87/U251/T98/U138 and HA1800 cell lines were verified by RT-qPCR. The nomogram in this study has been made available as a web version for clinicians. This 6-ORLs risk signature has the capabilities to predict the prognosis of glioma patients, assist in evaluating immune infiltration, and assess the efficacy of various anti-tumor systemic therapy regimens.

Conventional and new proposals of GnRH therapy for ovarian, breast, and prostatic cancers

For many years, luteinizing hormone-releasing hormone or gonadotropin-releasing hormone (GnRH) analogs have been used to treat androgen or estrogen-dependent tumors. However, emerging evidence shows that the GnRH receptor (GnRH-R) is overexpressed in several cancer cells, including ovarian, endometrial, and prostate cancer cells, suggesting that GnRH analogs could exert direct antitumoral actions in tumoral tissues that express GnRH-R. Another recent approach based on this knowledge was the use of GnRH peptides for developing specific targeted therapies, improving the delivery and accumulation of drugs in tumoral cells, and decreasing most side effects of current treatments. In this review, we discuss the conventional uses of GnRH analogs, together with the recent advances in GnRH-based drug delivery for ovarian, breast, and prostatic cancer cells.

Hormone therapy for ovarian cancer: Emphasis on mechanisms and applications (Review)

Ovarian cancer (OC) remains the leading cause of mortality due to gynecological malignancies. Epidemiological studies have demonstrated that steroid hormones released from the hypothalamic-pituitary-ovarian axis can play a role in stimulating or inhibiting OC progression, with gonadotropins, estrogens and androgens promoting OC progression, while gonadotropin-releasing hormone (GnRH) and progesterone may be protective factors in OC. Experimental studies have indicated that hormone receptors are expressed in OC cells and mediate the growth stimulatory or growth inhibitory effects of hormones on these cells. Hormone therapy agents have been evaluated in a number of clinical trials. The majority of these trials were conducted in patients with relapsed or refractory OC with average efficacy and limited side-effects. A better understanding of the mechanisms through which hormones affect cell growth may improve the efficacy of hormone therapy. In the present review article, the role of hormones (GnRH, gonadotropins, androgens, estrogens and progestins) and their receptors in OC tumorigenesis, and hormonal therapy in OC treatment is discussed and summarized.

Dissecting the Hormonal Signaling Landscape in Castration-Resistant Prostate Cancer

Understanding the molecular mechanisms underlying prostate cancer (PCa) progression towards its most aggressive, castration-resistant (CRPC) stage is urgently needed to improve the therapeutic options for this almost incurable pathology. Interestingly, CRPC is known to be characterized by a peculiar hormonal landscape. It is now well established that the androgen/androgen receptor (AR) axis is still active in CRPC cells. The persistent activity of this axis in PCa progression has been shown to be related to different mechanisms, such as intratumoral androgen synthesis, AR amplification and mutations, AR mRNA alternative splicing, increased expression/activity of AR-related transcription factors and coregulators. The hypothalamic gonadotropin-releasing hormone (GnRH), by binding to its specific receptors (GnRH-Rs) at the pituitary level, plays a pivotal role in the regulation of the reproductive functions. GnRH and GnRH-R are also expressed in different types of tumors, including PCa. Specifically, it has been demonstrated that, in CRPC cells, the activation of GnRH-Rs is associated with a significant antiproliferative/proapoptotic, antimetastatic and antiangiogenic activity. This antitumor activity is mainly mediated by the GnRH-R-associated Gαi/cAMP signaling pathway. In this review, we dissect the molecular mechanisms underlying the role of the androgen/AR and GnRH/GnRH-R axes in CRPC progression and the possible therapeutic implications.

Role of Gonadotropin-Releasing Hormone (GnRH) in Ovarian Cancer

The hypothalamus–pituitary–gonadal (HPG) axis is the endocrine regulation system that controls the woman’s cycle. The gonadotropin-releasing hormone (GnRH) plays the central role. In addition to the gonadotrophic cells of the pituitary, GnRH receptors are expressed in other reproductive organs, such as the ovary and in tumors originating from the ovary. In ovarian cancer, GnRH is involved in the regulation of proliferation and metastasis. The effects on ovarian tumors can be indirect or direct. GnRH acts indirectly via the HPG axis and directly via GnRH receptors on the surface of ovarian cancer cells. In this systematic review, we will give an overview of the role of GnRH in ovarian cancer development, progression and therapy.

The Role of Gonadotropin-Releasing Hormone (GnRH) in Endometrial Cancer

Endometrial cancer (EC) is one of the most common gynecological malignancies. Gonadotropin releasing hormone (GnRH) is a decapeptide first described to be secreted by the hypothalamus to regulate pituitary gonadotropin secretion. In this systematic review, we analyze and summarize the data indicating that most EC express GnRH and its receptor (GnRH-R) as part of an autocrine system regulating proliferation, the cell cycle, and apoptosis. We analyze the available data on the expression and function of GnRH-II, its putative receptor, and its signal transduction. GnRH-I and GnRH-II agonists, and antagonists as well as cytotoxic GnRH-I analogs, have been shown to inhibit proliferation and to induce apoptosis in human EC cell lines in pre-clinical models. Treatment with conventional doses of GnRH-agonists that suppress pituitary gonadotropin secretion and ovarian estrogen production has become part of fertility preserving therapy of early EC or its pre-cancer (atypical endometrial hyperplasia). Conventional doses of GnRH-agonists had marginal activity in advanced or recurrent EC. Higher doses or more potent analogs including GnRH-II antagonists have not yet been used clinically. The cytotoxic GnRH-analog Zoptarelin Doxorubicin has shown encouraging activity in a phase II trial in patients with advanced or recurrent EC, which expressed GnRH-R. In a phase III trial in patients with EC of unknown GnRH-R expression, the cytotoxic GnRH doxorubicin conjugate was not superior to free doxorubicin. Further well-designed clinical trials exploiting the GnRH-system in EC might be useful.

Gonadotropin-releasing hormone analogs: Mechanisms of action and clinical applications in female reproduction

Extra-hypothalamic GnRH and extra-pituitary GnRH receptors exist in multiple human reproductive tissues, including the ovary, endometrium and myometrium. Recently, new analogs (agonists and antagonists) and modes of GnRH have been developed for clinical application during controlled ovarian hyperstimulation for assisted reproductive technology (ART). Additionally, the analogs and upstream regulators of GnRH suppress gonadotropin secretion and regulate the functions of the reproductive axis. GnRH signaling is primarily involved in the direct control of female reproduction. The cellular mechanisms and action of the GnRH/GnRH receptor system have been clinically applied for the treatment of reproductive disorders and have widely been introduced in ART. New GnRH analogs, such as long-acting GnRH analogs and oral nonpeptide GnRH antagonists, are being continuously developed for clinical application. The identification of the upstream regulators of GnRH, such as kisspeptin and neurokinin B, provides promising potential to develop these upstream regulator-related analogs to control the hypothalamus-pituitary-ovarian axis.

Treatment of Breast Cancer With Gonadotropin-Releasing Hormone Analogs

Although significant progress has been made in the implementation of new breast cancer treatments over the last three decades, this neoplasm annually continues to show high worldwide rates of morbidity and mortality. In consequence, the search for novel therapies with greater effectiveness and specificity has not come to a stop. Among the alternative therapeutic targets, the human gonadotropin-releasing hormone type I and type II (hGnRH-I and hGnRH–II, respectively) and its receptor, the human gonadotropin-releasing hormone receptor type I (hGnRHR-I), have shown to be powerful therapeutic targets to decrease the adverse effects of this disease. In the present review, we describe how the administration of GnRH analogs is able to reduce circulating concentrations of estrogen in premenopausal women through their action on the hypothalamus–pituitary–ovarian axis, consequently reducing the growth of breast tumors and disease recurrence. Also, it has been mentioned that, regardless of the suppression of synthesis and secretion of ovarian steroids, GnRH agonists exert direct anticancer action, such as the reduction of tumor growth and cell invasion. In addition, we discuss the effects on breast cancer of the hGnRH-I and hGnRH-II agonist and antagonist, non-peptide GnRH antagonists, and cytotoxic analogs of GnRH and their implication as novel adjuvant therapies as antitumor agents for reducing the adverse effects of breast cancer. In conclusion, we suggest that the hGnRH/hGnRHR system is a promising target for pharmaceutical development in the treatment of breast cancer, especially for the treatment of advanced states of this disease.

Synthesis, characterization and systematic comparison of FITC-labelled GnRH-I, -II and -III analogues on various tumour cells

Targeted tumour therapy is the focus of recent cancer research. Gonadotropin-releasing hormone (GnRH) analogues are able to deliver anticancer agents selectively into tumour cells, which highly express GnRH receptors. However, the effectiveness of different analogues as targeting moiety in drug delivery systems is rarely compared, and the investigated types of cancer are also limited. Therefore, we prepared selectively labelled, fluorescent derivatives of GnRH-I, -II and -III analogues, which were successfully used for drug targeting. In this manuscript, we investigated these analogues' solubility, stability and passive membrane permeability and compared their cellular uptake by various cancer cells. We found that these labelled GnRH conjugates provide great detectability, without undesired cytotoxicity and passive membrane permeability. The introduced experiments with these conjugates proved their reliable tracking, quantification and comparison. Cellular uptake efficiency was studied on human breast, colon, pancreas and prostate cancer cells (MCF-7, HT-29, BxPC-3, LNCaP) and on dog kidney cells (Madin-Darby canine kidney). Each of the three conjugates was taken up by GnRH-I receptor-expressing cells, but the different cells preferred different analogues. Furthermore, we demonstrated for the first time the high cell surface expression of GnRH-I receptors and the effective cellular uptake of GnRH analogues on human pharynx tumour (Detroit-562) cells. In summary, our presented results detail that the introduced conjugates could be innovative tools for the examination of the GnRH-based drug delivery systems on various cells and offer novel information about these peptides. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

Overview of elagolix for the treatment of endometriosis

INTRODUCTION

Suppression of sex-steroid secretion is required in a variety of gynecological conditions. This can be achieved using gonadotropin releasing hormone (GnRH) agonists that bind pituitary gonadotropin receptors and antagonize the link-receptor of endogenous GnRH, inhibiting the mechanism of GnRH pulsatility. On the other hand, GnRH antagonists immediately reduce gonadal steroid levels, avoiding the initial stimulatory phase of the agonists. Potential benefits of GnRH antagonists over GnRH agonists include a rapid onset and reversibility of action. Older GnRH antagonists are synthetic peptides, obtained by modifications of certain amino acids in the native GnRH sequence. They require subcutaneous injections, implantation of long-acting depots. The peptide structure is responsible for histamine-related adverse events and the tendency to elicit hypersensitivity reactions.

AREAS COVERED

Research has worked towards the development of non-peptidic molecules exerting antagonist action on GnRH. They are available for oral administration and may have a more beneficial safety profile in comparison with peptide GnRH antagonists. This article focuses on the data of the literature about elagolix, a novel non-peptidic GnRHantagonist, in the treatment of endometriosis.

EXPERT OPINION

Elagolix demonstrated efficacy in the management of endometriosis-associated pain and had an acceptable safety and tolerability profile. However, further studies are necessary to evaluate its non-inferiority in comparison with other endometriosis's treatments.

Increased Uterine NK cell numbers and perforin expression during the implantation phase in IVF Cycles with GnRH Antagonist Protocol

GnRH antagonist negatively affects endometrial receptivity in in vitro fertilization (IVF) cycles, however, its underlying mechanism remains unclear. To explore its target molecules, we studied endometria in the window phase of fixed GnRH antagonist, low-dose flexible GnRH antagonist, GnRH agonist long protocol, and untreated control groups. There were 384 differentially expressed genes (DEGs) in the fixed antagonist group with greater than twofold expression change compared with the control group and 197 DEGs between the fixed antagonist and agonist groups, the majority of which were associated with the natural killer (NK) cell-mediated cytotoxicity pathway. We then analysed the PRF1 and FASLG protein levels. The perforin level were significantly higher in both the antagonist groups than in other two groups, and was higher in the fixed antagonist group. Similarly, the uNK cell numbers were higher in the antagonist groups, and the highest uNK cell number occurred in the fixed group (p < 0.05). No significant differences existed in the Fas ligand levels and apoptosis rates among the three treatment groups, but were higher in the treatment groups than the control group. Together, these data indicate that GnRH antagonist may increase the uNK cell numbers and perforin expression, and this effect may be dose-dependent.

Expression and Role of Gonadotropin-Releasing Hormone 2 and Its Receptor in Mammals

Gonadotropin-releasing hormone 1 (GnRH1) and its receptor (GnRHR1) drive mammalian reproduction via regulation of the gonadotropins. Yet, a second form of GnRH (GnRH2) and its receptor (GnRHR2) also exist in mammals. GnRH2 has been completely conserved throughout 500 million years of evolution, signifying high selection pressure and a critical biological role. However, the GnRH2 gene is absent (e.g., rat) or inactivated (e.g., cow and sheep) in some species but retained in others (e.g., human, horse, and pig). Likewise, many species (e.g., human, chimpanzee, cow, and sheep) retain the GnRHR2 gene but lack the appropriate coding sequence to produce a full-length protein due to gene coding errors; although production of GnRHR2 in humans remains controversial. Certain mammals lack the GnRHR2 gene (e.g., mouse) or most exons entirely (e.g., rat). In contrast, old world monkeys, musk shrews, and pigs maintain the coding sequence required to produce a functional GnRHR2. Like GnRHR1, GnRHR2 is a 7-transmembrane, G protein-coupled receptor that interacts with G_αq/11 to mediate cell signaling. However, GnRHR2 retains a cytoplasmic tail and is only 40% homologous to GnRHR1. A role for GnRH2 and its receptor in mammals has been elusive, likely because common laboratory models lack both the ligand and receptor. Uniquely, both GnRH2 and GnRHR2 are ubiquitously expressed; transcript levels are abundant in peripheral tissues and scarcely found in regions of the brain associated with gonadotropin secretion, suggesting a divergent role from GnRH1/GnRHR1. Indeed, GnRH2 and its receptor are not physiological modulators of gonadotropin secretion in mammals. Instead, GnRH2 and GnRHR2 coordinate the interaction between nutritional status and sexual behavior in the female brain. Within peripheral tissues, GnRH2 and its receptor are novel regulators of reproductive organs. GnRH2 and GnRHR2 directly stimulate steroidogenesis within the porcine testis. In the female, GnRH2 and its receptor may help mediate placental function, implantation, and ovarian steroidogenesis. Furthermore, both the GnRH2 and GnRHR2 genes are expressed in human reproductive tumors and represent emerging targets for cancer treatment. Thus, GnRH2 and GnRHR2 have diverse functions in mammals which remain largely unexplored.

The Role of Gonadotropin-Releasing Hormone in Cancer Cell Proliferation and Metastasis

In several human malignant tumors of the urogenital tract, including cancers of the endometrium, ovary, urinary bladder, and prostate, it has been possible to identify expression of gonadotropin-releasing hormone (GnRH) and its receptor as part of an autocrine system, which regulates cell proliferation. The expression of GnRH receptor has also been identified in breast cancers and non-reproductive cancers such as pancreatic cancers and glioblastoma. Various investigators have observed dose- and time-dependent growth inhibitory effects of GnRH agonists in cell lines derived from these cancers. GnRH antagonists have also shown marked growth inhibitory effects on most cancer cell lines. This indicates that in the GnRH system in cancer cells, there may not be a dichotomy between GnRH agonists and antagonists. The well-known signaling mechanisms of the GnRH receptor, which are present in pituitary gonadotrophs, are not involved in forwarding the antiproliferative effects of GnRH analogs in cancer cells. Instead, the GnRH receptor activates a phosphotyrosine phosphatase (PTP) and counteracts with the mitogenic signal transduction of growth factor receptors, which results in a reduction of cancer cell proliferation. The PTP activation, which is induced by GnRH, also inhibits G-protein-coupled estrogen receptor 1 (GPER), which is a membrane-bound receptor for estrogens. GPER plays an important role in breast cancers, which do not express the estrogen receptor α (ERα). In metastatic breast, ovarian, and endometrial cancer cells, GnRH reduces cell invasion in vitro, metastasis in vivo, and the increased expression of S100A4 and CYR61. All of these factors play important roles in epithelial-mesenchymal transition. This review will summarize the present state of knowledge about the GnRH receptor and its signaling in human cancers.

Effects of Di-(2-ethylhexyl) Phthalate on the Hypothalamus-Uterus in Pubertal Female Rats

The pollution of endocrine disruptors and its impact on human reproductive system have attracted much attention. Di-(2-ethylhexyl) phthalate (DEHP), an environmental endocrine disruptor, is widely used in food packages, containers, medical supplies and children's toys. It can cause diseases such as infertility, sexual precocity and uterine bleeding and thus arouse concerns from the society and scholars. The effect of DEHP on pubertal female reproductive system is still not well-studied. This study was to investigate the effects of DEHP on the hypothalamus-uterus in pubertal female rats, reveal the reproductive toxicity of DEHP on pubertal female rats and its mechanism, and provide scientific evidence for the evaluation of toxicity and toxic mechanism of DEHP on reproductive system. Forty-eight pubertal female rats were randomly divided into four groups and respectively administered via oral gavage 0, 250, 500, or 1000 mg/kg/d DEHP in 0.1 mL corn oil/20 g body weight for up to four weeks. Compared with control rats, the DEHP-treated rats showed: (1) higher gonadotropin-releasing hormone (GnRH) level in the hypothalamus; (2) higher protein levels of GnRH in the hypothalamus; and (3) higher mRNA and protein levels of GnRH receptor (GnRHR) in the uterus. Our data reveal that DEHP exposure may lead to a disruption in pubertal female rats and an imbalance of hypothalamus-uterus. Meanwhile, DEHP may, through the GnRH in the hypothalamus and its receptor on the uterus, lead to diseases of the uterus. DEHP may impose a negative influence on the development and functioning of the reproductive system in pubertal female rats.

Functional activity of the porcine Gnrhr2 gene promoter in testis-derived cells is partially conferred by nuclear factor-κB, specificity protein 1 and 3 (SP1/3) and overlapping early growth response 1/SP1/3 binding sites

Unlike the classical gonadotropin-releasing hormone (GnRH1), the second mammalian isoform (GnRH2) is ubiquitously expressed, suggesting a divergent function. Indeed, we demonstrated that GnRH2 governs LH-independent testosterone secretion in porcine testes via interaction with its receptor (GnRHR2) on Leydig cells. Transient transfections with luciferase reporter vectors containing 3009bp of 5' flanking sequence for the porcine Gnrhr2 gene (-3009pGL3) revealed promoter activity in all 15 cell lines examined, including swine testis-derived (ST) cells. Therefore, ST cells were utilized to explore the molecular mechanisms underlying transcriptional regulation of the porcine Gnrhr2 gene in the testis. Reporter plasmids containing progressive 5' deletions of the Gnrhr2 promoter indicated that the -708/-490 region contained elements critical to promoter activity. Electrophoretic mobility shift assays (EMSAs) with radiolabeled oligonucleotides spanning the -708/-490bp region and ST nuclear extracts, identified specific binding complexes for the -513/-490, -591/-571 and -606/-581bp segments of promoter. Antibody addition to EMSAs indicated that the p65 and p52 subunits of nuclear factor-κB (NF-κB) comprised the specific complex bound to the oligonucleotide probe for the -513/-490bp promoter region, specificity protein (SP) 1 and 3 bound the -591/-571bp probe and early growth response 1 (EGR1), SP1 and SP3 bound the -606/-581 radiolabeled oligonucleotide. Transient transfections with vectors containing mutations of the NF-κB (-499/-493), SP1/3 (-582/-575) or overlapping EGR1/SP1/3 (-597/-587) binding sites reduced luciferase activity by 26%, 61% and 56%, respectively (P<0.05). Thus, NF-κB, SP1/3 and overlapping EGR1/SP1/3 binding sites are critical to expression of the porcine Gnrhr2 gene in ST cells.

Luteinizing hormone-releasing hormone peptide tethered nanoparticulate system for enhanced antitumoral efficacy of paclitaxel

Aim: Paclitaxel (PTX) is an effective anticancer agent used in the therapy of a wide variety of cancers. However, the drug is difficult to formulate due to its low solubility, and therefore, it is administered under slow infusion with castor oil/ethanol solution as surfactant that causes serious side effects. This investigation investigates leutinizing hormone releasing hormone (LHRH)-tethered nanparticulate system as modality for cancer-specific delivery of PTX and therefore minimizing the adverse effects. Materials & methods: LHRH-tethered poly(lactic-co-glycolic acid) copolymer with poly ethylene glycol side chain was synthesized, characterized and employed to formulate PTX-loaded nanoparticulate system. Results & conclusion: The developed nanoparticulate appears to be proficient in carrying as well as targeted delivery of PTX with improved therapeutic efficacy and better safety.

Gonadotropin-releasing hormone stimulates biliary proliferation by paracrine/autocrine mechanisms

During cholestatic liver disease, there is dysregulation in the balance between biliary growth and loss in bile duct-ligated (BDL) rats modulated by neuroendocrine peptides via autocrine/paracrine pathways. Gonadotropin-releasing hormone (GnRH) is a trophic peptide hormone that modulates reproductive function and proliferation in many cell types. We evaluated the autocrine role of GnRH in the regulation of cholangiocyte proliferation. The expression of GnRH receptors was assessed in a normal mouse cholangiocyte cell line (NMC), sham, and BDL rats. The effect of GnRH administration was evaluated in normal rats and in NMC. GnRH-induced biliary proliferation was evaluated by changes in intrahepatic bile duct mass and the expression of proliferation and function markers. The expression and secretion of GnRH in NMC and isolated cholangiocytes was assessed. GnRH receptor subtypes GnRHR1 and GnRHR2 were expressed in cholangiocytes. Treatment with GnRH increased intrahepatic bile duct mass as well as proliferation and function markers in cholangiocytes. Transient knockdown and pharmacologic inhibition of GnRHR1 in NMC decreased proliferation. BDL cholangiocytes had increased expression of GnRH compared with normal rats, accompanied by increased GnRH secretion. In vivo and in vitro knockdown of GnRH decreased intrahepatic bile duct mass/cholangiocyte proliferation and fibrosis. GnRH secreted by cholangiocytes promotes biliary proliferation via an autocrine pathway. Disruption of GnRH/GnRHR signaling may be important for the management of cholestatic liver diseases.

Comparative in vitro biological evaluation of daunorubicin containing GnRH-I and GnRH-II conjugates developed for tumor targeting

Hormone based drug targeting is a promising tool for selective tumor therapy. In this study, synthesis and systematic comparative biological evaluation of novel drug containing analogs of gonadotropin-releasing hormone GnRH-I and GnRH-II is reported demonstrating their suitability for tumor targeting. The cytotoxic conjugates were prepared by the attachment of the chemotherapeutical agent daunorubicin (Dau) to GnRH analogs directly or through an enzyme-labile spacer with oxime linkage. All conjugates were found to be proteolytically stable under circumstances applied in biological assays. Both GnRH-I and GnRH-II were able to bind similarly to high-affinity GnRH-I receptors on human pituitary and human prostate cancer cells. The in vitro long-term cytotoxic effect of the conjugates was comparable with that of the free drug in human breast and colon cancer cell lines. Furthermore, a concentration-dependent cellular uptake profile was observed. The in vitro apoptotic effect of the compounds was evaluated by flow cytometry analysis using annexin-V. Our results show that both the GnRH-I and the GnRH-II based analogs might be applied for targeted tumor therapy.

Stability, permeability and growth-inhibitory properties of gonadotropin-releasing hormone liposaccharides

PURPOSE

In this study we aimed to address the poor drug-like properties of Gonadotropin-Releasing Hormone (GnRH) peptide through modification with lipids and carbohydrates.

METHODS

GnRH peptide was conjugated to 2-amino-D,L-octanoic acid (C8) and 2-amino-D,L-dodecanoic acid (C12) in monomer and dimer, along with (6-9) or without (2-5 and 11) a glucose moiety. Peptides were tested for their biological activity using different tumour cell lines. The toxicity of the constructs was evaluated in peripheral blood mononuclear cells (PBMC).

RESULTS

All (glyco)lipopeptides showed improved metabolic stability in Caco-2 cell homogenates. Those with single lipid moiety (2, 4 and 8) exhibited prodrug-like properties. Permeability across Caco-2 cell monolayers was enhanced in the dimer C8-modified (glyco)lipopeptide (3) and the lipopeptide with C12 inserted mid-sequence (11). Most of the constructs showed moderate-to-high antiproliferative activity against GnRH-receptor positive DU145 and OVCAR-3 cells (up to 60%). Compound 11 was the most effective with IC50 = 26.4 ± 1.07 μg.ml(-1), which was comparable to triptorelin (25.1 ± 1.14 μg.mL(-1)). The sensitivity of OVCAR-3 cells to the effect of all analogues except for 11 decreased significantly in estrogen-reconstituted media. Only compounds 2, 4, 5 and 8 showed a steroid-dependent effect in DU145 cells. No compounds exhibited significant toxicity on PBMCs.

CONCLUSION

These results indicated lipidation and glycosylation improves the druggability of GnRH and could lead to an increased direct antitumour activity in some hormone dependent and independent reproductive cancers.

Camptothecin prodrug block copolymer micelles with high drug loading and target specificity

The effects of a novel functional reducible camptothecin (CPT) block copolymer conjugate, targeting luteinizing hormone releasing hormone receptor (LHRHR) were evaluated against differing LHRHR expressing tumour cell lines and immune populations.

Influence of gonadotropin-releasing hormone agonist on the effect of chemotherapy upon ovarian cancer and the prevention of chemotherapy-induced ovarian damage: an experimental study with nu/nu athymic mice

BACKGROUND AND OBJECTIVE

Gonadotropin-releasing hormone (GnRH) plays an important role in the regulation of ovarian function and ovarian cancer cell growth. In this study, we determined whether administration of the GnRH agonist (GnRHa), triporelin, prior to cisplatin treatment affects cisplatin and/or prevents cisplatin-induced ovarian damage.

METHODS

nu/nu mice were injected with ovarian cancer OVCAR-3 cells intraperitoneally. After two weeks, the mice were treated with saline (control), cisplatin, GnRHa, or cisplatin plus GnRHa for four weeks. At the end of the experimental protocol, blood, tumor, ovary, and uterine tissues were resected for hematoxylin and eosin (H&E) staining, immunohistochemical analyses of Ki67, nuclear factor-κB (NF-κB), and caspase-3, transmission electron microscopy of apoptosis, or enzyme-linked immunosorbent assay (ELISA) analyses of anti-Mullerian hormone (AMH).

RESULTS

Cisplatin treatment effectively inhibited tumor growth in mice treated with human ovarian cancer cells; however the treatment also induced considerable toxicity. Immunohistochemical analyses showed that Ki67 expression was reduced in cisplatin-treated mice compared to control (P<0.05), but there was no statistically significant differences between cisplatin-treated mice and cisplatin plus GnRHa-treated mice (P>0.05), while expressions of NF-κB and caspase-3 were reduced and induced, respectively, in cisplatin-treated mice and cisplatin plus GnRHa-treated mice. Apoptosis occurred in the GnRHa, cisplatin, and cisplatin plus GnRHa-treated mice, but not in control mice. Ovaries exposed to GnRHa in both GnRHa mice and cisplatin-treated mice (combination group) had significantly more primordial and growth follicles and serum levels of AMH than those in the control mice and cisplatin-treated mice (P<0.05).

CONCLUSIONS

Administration of GnRHa to mice significantly decreased the extent of ovarian damage induced by cisplatin, but did not affect the anti-tumor activity of cisplatin.

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

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.

Transcript and protein profiling identifies signaling, growth arrest, apoptosis, and NF-κB survival signatures following GNRH receptor activation

GNRH significantly inhibits proliferation of a proportion of cancer cell lines by activating GNRH receptor (GNRHR)-G protein signaling. Therefore, manipulation of GNRHR signaling may have an under-utilized role in treating certain breast and ovarian cancers. However, the precise signaling pathways necessary for the effect and the features of cellular responses remain poorly defined. We used transcriptomic and proteomic profiling approaches to characterize the effects of GNRHR activation in sensitive cells (HEK293-GNRHR, SCL60) in vitro and in vivo, compared to unresponsive HEK293. Analyses of gene expression demonstrated a dynamic response to the GNRH superagonist Triptorelin. Early and mid-phase changes (0.5-1.0 h) comprised mainly transcription factors. Later changes (8-24 h) included a GNRH target gene, CGA, and up- or downregulation of transcripts encoding signaling and cell division machinery. Pathway analysis identified altered MAPK and cell cycle pathways, consistent with occurrence of G(2)/M arrest and apoptosis. Nuclear factor kappa B (NF-κB) pathway gene transcripts were differentially expressed between control and Triptorelin-treated SCL60 cultures. Reverse-phase protein and phospho-proteomic array analyses profiled responses in cultured cells and SCL60 xenografts in vivo during Triptorelin anti-proliferation. Increased phosphorylated NF-κB (p65) occurred in SCL60 in vitro, and p-NF-κB and IκBε were higher in treated xenografts than controls after 4 days Triptorelin. NF-κB inhibition enhanced the anti-proliferative effect of Triptorelin in SCL60 cultures. This study reveals details of pathways interacting with intense GNRHR signaling, identifies potential anti-proliferative target genes, and implicates the NF-κB survival pathway as a node for enhancing GNRH agonist-induced anti-proliferation.

GnRH receptors in cancer: from cell biology to novel targeted therapeutic strategies

The crucial role of pituitary GnRH receptors (GnRH-R) in the control of reproductive functions is well established. These receptors are the target of GnRH agonists (through receptor desensitization) and antagonists (through receptor blockade) for the treatment of steroid-dependent pathologies, including hormone-dependent tumors. It has also become increasingly clear that GnRH-R are expressed in cancer tissues, either related (i.e. prostate, breast, endometrial, and ovarian cancers) or unrelated (i.e. melanoma, glioblastoma, lung, and pancreatic cancers) to the reproductive system. In hormone-related tumors, GnRH-R appear to be expressed even when the tumor has escaped steroid dependence (such as castration-resistant prostate cancer). These receptors are coupled to a G(αi)-mediated intracellular signaling pathway. Activation of tumor GnRH-R by means of GnRH agonists elicits a strong antiproliferative, antimetastatic, and antiangiogenic (more recently demonstrated) activity. Interestingly, GnRH antagonists have also been shown to elicit a direct antitumor effect; thus, these compounds behave as antagonists of GnRH-R at the pituitary level and as agonists of the same receptors expressed in tumors. According to the ligand-induced selective-signaling theory, GnRH-R might assume various conformations, endowed with different activities for GnRH analogs and with different intracellular signaling pathways, according to the cell context. Based on these consistent experimental observations, tumor GnRH-R are now considered a very interesting candidate for novel molecular, GnRH analog-based, targeted strategies for the treatment of tumors expressing these receptors. These agents include GnRH agonists and antagonists, GnRH analog-based cytotoxic (i.e. doxorubicin) or nutraceutic (i.e. curcumin) hybrids, and GnRH-R-targeted nanoparticles delivering anticancer compounds.

Inhibition of the AKT/mTOR and erbB pathways by gefitinib, perifosine and analogs of gonadotropin-releasing hormone I and II to overcome tamoxifen resistance in breast cancer cells

Endocrine resistance in breast cancer remains a major clinical problem and is caused by crosstalk mechanisms of growth factor receptor cascades, such as the erbB and PI3K/AKT pathways. The possibilities a single breast cancer cell has to achieve resistance are manifold. We developed a model of 4-hydroxy-tamoxifen (OHT)‑resistant human breast cancer cell lines and compared their different expression patterns, activation of growth factor receptor pathways and compared cells by genomic hybridization (CGH). We also tested a panel of selective inhibitors of the erbB and AKT/mTOR pathways to overcome OHT resistance. OHT‑resistant MCF-7-TR and T47D-TR cells showed increased expression of HER2 and activation of AKT. T47D-TR cells showed EGFR expression and activated MAPK (ERK-1/2), whereas in resistant MCF-7-TR cells activated AKT was due to loss of CTMP expression. CGH analyses revealed remarkable aberrations in resistant sublines, which were predominantly depletions. Gefitinib inhibited erbB signalling and restored OHT sensitivity in T47D-TR cells. The AKT inhibitor perifosine restored OHT sensitivity in MCF-7-TR cells. All cell lines showed expression of receptors for gonadotropin-releasing hormone (GnRH) I and II, and analogs of GnRH-I/II restored OHT sensitivity in both resistant cell lines by inhibition of erbB and AKT signalling. In conclusion, mechanisms to escape endocrine treatment in breast cancer share similarities in expression profiling but are based on substantially different genetic aberrations. Evaluation of activated mediators of growth factor receptor cascades is helpful to predict response to specific inhibitors. Expression of GnRH-I/II receptors provides multi-targeting treatment strategies.

Apoptin gene transfer via modified wheat histone H4 facilitates apoptosis of human ovarian cancer cells

Nonviral approaches have been used extensively for intracellular gene transfer and gene therapy. A modified wheat histone H4 protein, H4TL (H4-TAT-LHRH), as a protein-based gene delivery vector that was able to form stable complexes with plasmid DNA and increase gene delivery efficiency has been described previously. In this study, H4TL has been used to deliver apoptin gene into a human ovarian carcinoma cell line HO8910. After transfection, increased expression of apoptin at both mRNA and protein levels was detected in HO8910 cells, accompanied by reduced rate of growth of HO8910 cells in vitro and the loss of mitochondrial membrane potential in these cells. These data demonstrate that H4TL-mediated transfer of apoptin initiates mitochondrial death pathway in ovarian cancer cells and suggest a novel therapeutic strategy for cancer.

GnRH agonist (buserelin)-induced in vitro apoptosis in bovine endometrium

Singh, R., Pretheeban, T. and Rajamahendran, R. 2011. GnRH agonist (buserelin)-induced in vitro apoptosis in bovine endometrium. Can. J. Anim. Sci. 91: 265–273. Apoptosis is a vital physiological process. The local modulatory role of the GnRH, GnRH-R system in uterine physiology is not clear. We investigated GnRH agonist (buserelin)-induced apoptosis in bovine endometrium. Reproductive tracts were collected from a local abattoir. The endometrial explants were sliced into smaller pieces, cultured for 20 h and then treated (6 h) with buserelin (0, 200, 500, 1000 ng mL−1), the GnRH antagonist-antide (500 ng mL−1) and antide+buserelin (500+200 ng mL−1), and stored at −80°C for RNA extraction. Two micrograms of total RNA was subjected to reverse transcription-polymerase chain reaction using gene-specific primers. Subsequently, endometrial epithelial cells were isolated from the follicular and luteal phase uteri, cultured for 48 h, characterized and treated with buserelin (200 ng mL−1), antide (500 ng mL−1), and antide+buserelin (500+200 ng mL−1) for 6 h. The cells were stained with acridine orange-ethidium bromide and visualized and counted under a fluorescent microscope. Buserelin up-regulated BAX (200 ng mL−1) and CASPASE3 mRNA (200 and 500 ng mL−1) and induced apoptosis (200 ng mL−1) at the cellular level in the follicular phase endometrium. GnRH appears to regulate uterine homeostasis in bovine endometrium at the transcriptional and cellular levels.

Neuropeptides in the gonads: from evolution to pharmacology

Vertebrate gonads are the sites of synthesis and binding of many peptides that were initially classified as neuropeptides. These gonadal neuropeptide systems are neither well understood in isolation, nor in their interactions with other neuropeptide systems. Further, our knowledge of the control of these gonadal neuropeptides by peripheral hormones that bind to the gonads, and which themselves are under regulation by true neuropeptide systems from the hypothalamus, is relatively meager. This review discusses the existence of a variety of neuropeptides and their receptors which have been discovered in vertebrate gonads, and the possible way in which such systems could have evolved. We then focus on two key neuropeptides for regulation of the hypothalamo-pituitary-gonadal axis: gonadotropin-releasing hormone (GnRH) and gonadotropin-inhibitory hormone (GnIH). Comparative studies have provided us with a degree of understanding as to how a gonadal GnRH system might have evolved, and they have been responsible for the discovery of GnIH and its gonadal counterpart. We attempt to highlight what is known about these two key gonadal neuropeptides, how their actions differ from their hypothalamic counterparts, and how we might learn from comparative studies of them and other gonadal neuropeptides in terms of pharmacology, reproductive physiology and evolutionary biology.

Effect of GnRH analogues and octreotide treatment on apoptosis and the cell proliferation of endometrium adenocarcinoma cell lines

OBJECTIVE

The aim of this study was to compare apoptotic and antiproliferative effects of gonadotropin-releasing hormone analogues and their combination with octeotide on endometrioid endometrial cancer cell lines.

MATERIAL AND METHOD

Women diagnosed with endometrioid adenocarcinoma at the department of Gynecology and Obstetric of Kocaeli University Medical School were included in this research. Endometrium cancer cell lines obtained from three patients were used for this study. After trypsinization in 0.5% in calcium magnesium, free phosphate buffer solution (CMFPBS) cells were seeded on glass slides in 24-well plates containing DMEM-F12 medium and 10% fetal calf serum as culture medium. Cells were incubated for 24 hours at 37ºC in 5% CO2. GnRH agonist leuprolide (Lucrin 1 μmol/L), GnRH antagonist ganirelix (Orgalutran 1 μmol/L), leuprolide with octreotide (Sandostatin 10-6 mol/L), ganirelix with octreotide and no drug were added to the wells. Apoptosis and cells proliferations were evaluated after 12, 24, 48 and 72(th) hours of incubation. The percentage of apoptotic cells was evaluated by TdT mediated biotin-dUTP nick-end labeling (TUNEL) method; cell proliferation was assessed by bromodeoxyuridine (BrdU) incorporation.

RESULTS

Apoptotic index in grade I EEC cell line among ganirelixoctreotide treated cells and leuprolide-octreotide combination therapy were respectively higher than the untreated control (p<0.001, p=0.001). The number of apoptotic cells in grade II EEC cell line among leuprolide-octreotide and leuprolide were significantly (p<0.001, p<0.001) higher than in controls. In grade III EEC cell line, the number of TUNEL positive cells among leuprolide, ganirelix and ganirelixoctreotide therapiy groups were significantly higher than in untreated control. Time dependent antiproliferative effect was obtained with leuprolide and leuprolide-octreotide in grade I EEC (p<0.001, p<0.001). Grade II EEC cell line is not influenced by hormonotherapies. However, the antiproliferative effect was obtained with ganirelix, leuprolide and leuprolide-octreotide in grade III cell line.

CONCLUSION

GnRH analogues appears to have a direct effect, enhancing the apoptotic index and decreasing the cell proliferation in endometrial adenocancer cell lines.

Gonadotropin-releasing hormone type II antagonist induces apoptosis in MCF-7 and triple-negative MDA-MB-231 human breast cancer cells in vitro and in vivo

Introduction

Triple-negative breast cancer does not express estrogen and progesterone receptors, and no overexpression/amplification of the HER2-neu gene occurs. Therefore, this subtype of breast cancer lacks the benefits of specific therapies that target these receptors. Today chemotherapy is the only systematic therapy for patients with triple-negative breast cancer. About 50% to 64% of human breast cancers express receptors for gonadotropin-releasing hormone (GnRH), which might be used as a target. New targeted therapies are warranted. Recently, we showed that antagonists of gonadotropin-releasing hormone type II (GnRH-II) induce apoptosis in human endometrial and ovarian cancer cells in vitro and in vivo. This was mediated through activation of stress-induced mitogen-activated protein kinases (MAPKs) p38 and c-Jun N-terminal kinase (JNK), followed by activation of proapoptotic protein Bax, loss of mitochondrial membrane potential, and activation of caspase-3. In the present study, we analyzed whether GnRH-II antagonists induce apoptosis in MCF-7 and triple-negative MDA-MB-231 human breast cancer cells that express GnRH receptors. In addition, we ascertained whether knockdown of GnRH-I receptor expression affects GnRH-II antagonist-induced apoptosis and apoptotic signaling.

Methods

Induction of apoptosis was analyzed by measurement of the loss of mitochondrial membrane potential. Apoptotic signaling was measured with quantification of activated MAPK p38 and caspase-3 by using the Western blot technique. GnRH-I receptor protein expression was inhibited by using the antisense knockdown technique. In vivo experiments were performed by using nude mice bearing xenografted human breast tumors.

Results

We showed that treatment of MCF-7 and triple-negative MDA-MB-231 human breast cancer cells with a GnRH-II antagonist results in apoptotic cell death in vitro via activation of stress-activated MAPK p38 and loss of mitochondrial membrane potential. In addition, we showed GnRH-II antagonist-induced activation of caspase-3 in MDA-MB-231 human breast cancer cells. After knockdown of GnRH-I receptor expression, GnRH-II antagonist-induced apoptosis and apoptotic signaling was only slightly reduced, indicating that an additional pathway mediating the effects of GnRH-II antagonists may exist. The GnRH-I receptor seems not to be the only target of GnRH-II antagonists. The antitumor effects of the GnRH-II antagonist could be confirmed in nude mice. The GnRH-II antagonist inhibited the growth of xenotransplants of human breast cancers in nude mice completely, without any apparent side effects.

Conclusions

GnRH-II antagonists seem to be suitable drugs for an efficacious and less-toxic endocrine therapy for breast cancers, including triple-negative breast cancers.

Anticancer activity of a new gonadotropin releasing hormone analogue

Gonadotropin releasing hormone (GnRH) has a pivotal role in the biology of reproduction processes. In extrapituitary compartments GnRH and its receptor act as a part of the autocrin regulatory system of cell proliferation, resulting in its anticancer activity. Here the anticancer activity of a new analogue of GnRH has been investigated. Results indicate that proliferation of human breast and ovarian cancer cell lines is dose-dependently inhibited. The inhibitory efficiency of this new analogue is proved to be higher than the original triptorelin. In addition to its antimitogenic activity, evidence was found for the involvement of the apoptotic mechanism in the action of the new analogue. Furthermore the presence of chemical groups in the peptide sequence is thought to increase the protease stability of the new analogue in comparison with triptorelin. Consequently our new analogue can be considered as a good pharmaceutical candidate.

Receptor-mediated tumor targeting based on peptide hormones

IMPORTANCE OF THE FIELD

Tumor targeting with peptides is based on the discovery that receptors for many regulatory peptides are overexpressed in tumor cells, compared with their expression in normal tissues. Consequently, these peptides and their analogues can be used as carriers/targeting moieties for the preparation of diagnostic and therapeutic agents that have increased selectivity and decreased peripheral toxicity.

AREAS COVERED IN THIS REVIEW

Here an overview is given of the most relevant gonadotropin-releasing hormone (GnRH) and somatostatin derivatives, as well as of their applications in cancer diagnosis and therapy. For this purpose, recently published data in these areas (mostly articles published from 2000 to 2009) were reviewed.

WHAT THE READER WILL GAIN

In contrast to other regulatory peptides that stimulate the tumor growth, GnRH and somatostatin derivatives have inhibitory effect; therefore, they were used primarily for the preparation of various conjugates to be used in targeted chemotherapy, targeted radiotherapy, photodynamic therapy, boron neutron capture therapy and cancer diagnosis. Some of these conjugates have already found clinical applications, whereas others are now in preclinical and clinical trials.

TAKE HOME MESSAGE

Tumor targeting with hormone peptides provides a basis for the development of new diagnostic and therapeutic approaches for cancer.

Functional exploration of the adult ovarian granulosa cell tumor-associated somatic FOXL2 mutation p.Cys134Trp (c.402C>G)

Background

The somatic mutation in the FOXL2 gene c.402C>G (p.Cys134Trp) has recently been identified in the vast majority of adult ovarian granulosa cell tumors (OGCTs) studied. In addition, this mutation seems to be specific to adult OGCTs and is likely to be a driver of malignant transformation. However, its pathogenic mechanisms remain elusive.

Methodology/Principal Findings

We have sequenced the FOXL2 open reading frame in a panel of tumor cell lines (NCI-60, colorectal carcinoma cell lines, JEG-3, and KGN cells). We found the FOXL2 c.402C>G mutation in the adult OGCT-derived KGN cell line. All other cell lines analyzed were negative for the mutation. In order to gain insights into the pathogenic mechanism of the p.Cys134Trp mutation, the subcellular localization and mobility of the mutant protein were studied and found to be no different from those of the wild type (WT). Furthermore, its transactivation ability was in most cases similar to that of the WT protein, including in conditions of oxidative stress. A notable exception was an artificial promoter known to be coregulated by FOXL2 and Smad3, suggesting a potential modification of their interaction. We generated a 3D structural model of the p.Cys134Trp variant and our analysis suggests that homodimer formation might also be disturbed by the mutation.

Conclusions/Significance

Here, we confirm the specificity of the FOXL2 c.402C>G mutation in adult OGCTs and begin the exploration of its molecular significance. This is the first study demonstrating that the p.Cys134Trp mutant does not have a strong impact on FOXL2 localization, solubility, and transactivation abilities on a panel of proven target promoters, behaving neither as a dominant-negative nor as a loss-of-function mutation. Further studies are required to understand the specific molecular effects of this outstanding FOXL2 mutation.

GnRH I and II up-regulate MMP-26 expression through the JNK pathway in human cytotrophoblasts

BACKGROUND

Matrix metalloproteinase-26 (MMP-26), one of the main mediators of extracellular matrix (ECM) degradation, has been shown to exist in trophoblasts of human placenta and to play a role in trophoblast cell invasion. However, little is known about the regulation of MMP-26 expression in human trophoblasts. Recently, gonadotropin-releasing hormone I (GnRH I) and GnRH II have been shown to regulate the expression of MMP-2, MMP-9/tissue inhibitor of metalloproteinases 1 (TIMP-1), and urokinase plasminogen activator (uPA)/plasminogen activator inhibitor (PAI) in human trophoblasts, suggesting that these two hormones may work as paracrine and/or autocrine regulators in modulating the activities of various protease systems at the feto-maternal interface. In this study, we determined the regulatory effects of GnRH I and GnRH II on the expression of MMP-26 in human immortalized cytotrophoblast-like cell line, B6Tert-1.

METHODS

Real-time PCR was used to quantify mRNA levels of MMP-26 in human trophoblast-like cell line, B6Tert-1 and primary cultured cytotrophoblasts. Western blotting was used to characterize the expression of MMP-26 and the phosphorylation of c-Jun NH2-terminal kinase (JNK) and extracellular signal-regulated kinase 1/2 (ERK1/2) in B6Tert-1 cells after treatment with GnRH I and GnRH II.

RESULTS

We found that GnRH I increased MMP-26 expression in B6Tert-1 cells after 12 h of treatment at both the mRNA and protein level, while GnRH II increased MMP-26 expression beginning at 3 h of treatment. Treatment of GnRH I at 1 nM resulted in maximal increase of MMP-26 mRNA and protein levels, whereas GnRH II treatment at a concentration of 100 nM was required to induce maximal increase in MMP-26 expression. In addition, we demonstrated that the activation of JNK, but not ERK1/2, was required for GnRH I and II-stimulated MMP-26 production in B6Tert-1 cells and primary cytotrophoblasts.

CONCLUSIONS

These novel findings indicated that GnRH I and II could up-regulate MMP-26 expression through the JNK signaling pathway in human trophoblast-like/trophoblast cells.

GnRH-II mRNA expression in tumor tissue and peripheral blood mononuclear cells (PBMCs) in patients with malignant and benign ovarian tumors

OBJECTIVE

To investigate the expression of the second form of GnRH (GnRH-II) in tumor tissue and peripheral blood mononuclear cells (PBMCs) in malignant and benign ovarian tumors in humans.

STUDY DESIGN

Sixty-six women were studied: 24 with epithelial ovarian carcinomas, 22 with benign ovarian tumors and 20 in the control group undergoing surgery. Malignant, benign and normal ovarian tissue and PBMCs were obtained for measurement of GnRH-II mRNA levels using quantitative real-time RT-PCR.

RESULT(S)

The expression of GnRH-II was found to be 1.5 times higher in malignant ovarian tumors compared with benign ovarian tumors and the control group in post-menopausal patients (P<0.01). In the post-menopausal patient group with malignant ovarian tumors, there were significant positive correlations between serum FSH level and ovarian tissue GnRH-II mRNA expression (r=0.68; P=0.03), and serum LH level and ovarian tissue GnRH-II mRNA expression (r=0.71; P=0.02). Controls, benign and malignant groups were similar in terms of GnRH-II expression in PBMCs in the pre- and post-menopausal periods. There was no significant correlation between ovarian tissue GnRH-II mRNA expression vs. PBMC GnRH-II mRNA expression in patient and control groups.

CONCLUSION(S)

We have shown increased GnRH-II expression in human ovarian cancer tissue in post-menopausal women in vivo. Expression of GnRH-II in PBMCs did not reflect the local GnRH-II expression levels in ovarian tissue. These preliminary data suggest that local GnRH-II may participate in the regulation of ovarian tumor growth in post-menopausal women.

Decreased expression of Beclin 1 in eutopic endometrium of women with adenomyosis

PURPOSE

Researchers have launched a new area of febrile investigations on the autophagy-related gene Beclin 1. Our aim is to investigate whether Beclin 1 expression is altered in eutopic endometrium of women with adenomyosis and its association with clinical characteristics.

METHODS

We collected tissue samples from the eutopic endometria of 30 women with adenomyosis and 32 healthy women undergoing surgery for benign indications. We cultured the stromal cells of the eutopic endometria. Beclin 1 expression of the cultured stromal cells and tissues was assessed by reverse transcription polymerase chain reaction and western blot analysis.

RESULTS

Beclin 1 messenger RNA (mRNA) expression in cultured stromal cells of eutopic endometria and endometrial tissues of women with adenomyosis was significantly lower than that of controls (P < 0.05). Beclin 1 protein expression in cultured stromal cells of eutopic endometria and endometrial tissues of adenomyosis was also significantly lower compared with that of controls (P < 0.01). Beclin 1 protein expression in eutopic endometrial tissues was negatively correlated with serum CA125 (r = -0.307, P = 0.015), and pelvic pain (r = -0.542, P = 0.000).

CONCLUSIONS

The study revealed Beclin 1 mRNA and protein expression were significantly decreased in eutopic endometria of women with adenomyosis. Moreover, Beclin 1 was negatively correlated with serum CA125 and pelvic pain. Beclin 1 might contribute to the pathogenesis and progression of endometriosis. Further research on autophagy of adenomyosis is required.

Epidermal growth factor-induced GnRH-II synthesis contributes to ovarian cancer cell invasion

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.

Type I gonadotropin-releasing hormone receptor mediates the antiproliferative effects of GnRH-II on prostate cancer cells

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.

Promotion of human trophoblasts invasion by gonadotropin-releasing hormone (GnRH) I and GnRH II via distinct signaling pathways

The potential roles of GnRH I and GnRH II have been assigned in promoting the invasive capacity of human trophoblasts by regulating matrix metalloproteinases-2 and -9, type I tissue inhibitor of matrix metalloproteinase, and urokinase plasminogen activator/plasminogen activator inhibitor protease systems during human placentation, and GnRH II has been shown to be more potent than GnRH I. However, the mechanisms for the differential effects of these two hormones remain unclear. In this study, we examined the invasion-promoting effects and the signaling pathways of GnRH I and GnRH II in human trophoblasts. The data revealed that both GnRH I and GnRH II were key autocrine and/or paracrine regulators in facilitating trophoblast invasion. The GnRH receptor antagonist (Antide) and specific small interfering RNA for GnRH receptor inhibited the regulatory effects of GnRH I, but not GnRH II, on trophoblast invasion. Both GnRH I and II activated protein kinase C, ERK1/2, and c-Jun N-terminal kinase to mediate their effects on trophoblast invasion, whereas only GnRH II elicited invasion-promoting action through transactivating the tyrosine kinase activity of epidermal growth factor receptor in trophoblasts. Our observations elucidate a ligand-dependent selective cross-communication between GnRH receptor and epidermal growth factor receptor signaling systems in human trophoblastic cell, and this would further our understanding on the differentially biological significance of these two forms of GnRH in extrapituitary tissues.

Cessation of gonadotropin-releasing hormone antagonist on triggering day: an alternative method for flexible multiple-dose protocol

This study was performed to analyze retrospectively outcomes of stimulated in vitro fertilization (IVF) cycles where the gonadotropin-releasing hormone (GnRH) antagonist was omitted on ovulation triggering day. A total of 92 consecutive IVF cycles were included in 65 women who are undergoing ovarian stimulation with recombinant FSH. A GnRH antagonist, cetrorelix 0.25 mg/day, was started when leading follicle reached 14 mm in diameter until the day of hCG administration (Group A, 66 cycles) or until the day before hCG administration (Group B, 26 cycles). The duration of ovarian stimulation, total dose of gonadotropins, serum estradiol levels on hCG administration day, and the number of oocytes retrieved were not significantly different between the two groups. The total dose of GnRH antagonist was significantly lower in Group B compared to Group A (2.7+/-0.8 vs. 3.2+/-0.9 ampoules). There was no premature luteinization in the subjects. The proportion of mature oocytes (71.4% vs. 61.7%) and fertilization rate of mature (86.3+/-19.7% vs. 71.8+/-31.7%) was significantly higher in Group B. There were no significant differences in embryo quality and clinical pregnancy rates. Our results suggest that cessation of the GnRH antagonist on the day of hCG administration during a flexible multiple-dose protocol could reduce the total dose of GnRH antagonist without compromising IVF results.

Gonadotropin-releasing hormone receptor expression in endometrial cancer

Several studies have previously reported the expression of the gonadotropin-releasing hormone receptor (GnRHr) in cases of endometrial cancer. However, the relationship between GnRHr expression and a variety of clinicopathologic parameters remains unclear. This study was conducted with 141 endometrial cancer patients, all of whom had undergone operations between 1993 and 2002. Paraffin-embedded tissue blocks were sectioned and immunostained with monoclonal anti-GnRHr antibody. Clinicopathologic variables were also evaluated, with 10% cutoff values for GnRHr positivity. Seventy specimens (49.6%) stained as GnRHr-positive. Mean parity was higher in the patients with GnRHr-positive tumors than those with GnRHr-negative tumors (2.50+/-1.92 versus 1.82+/-1.37, P=0.016). Body mass indices were also higher in the patients with GnRHr-positive tumors (26.6+/-4.6 versus 24.7+/-4.2, P=0.010). However, GnRHr positivity was not determined to be statistically significantly associated with any other clinicopathologic characteristics, including age, menopausal status, histotype, disease stage, tumor differentiation, lymph node metastasis, and myometrial invasion. The results of this study, although they may require further investigation, suggested that obese and multiparous women with endometrial cancer might be greatly influenced by endogenous gonadotropin-releasing hormone and/or exogenous gonadotropin-releasing hormone analogs.

Temporal recruitment of transcription factors at the 3',5'-cyclic adenosine 5'-monophosphate-response element of the human GnRH-II promoter

GnRH-II is a potent GnRH subtype involved in modulating OVCAR-3 cell proliferation and the invasive properties of JEG-3 cells, and an atypical cAMP-response element (CRE) in the human GnRH-II promoter influences its activation. We demonstrated that the GnRH-II promoter is activated by 8-bromoadenosine-cAMP in several cell lines including alphaT3, TE671, JEG-3, and OVCAR-3 cells and that cAMP enhances GnRH-II mRNA levels in JEG-3 and OVCAR-3 cells. Moreover, 8-bromoadenosine-cAMP increases cAMP response element-binding protein (CREB) phosphorylation in JEG-3 and OVCAR-3 cells and augments CBP and CCAAT/enhancer-binding protein (C/EBP)-beta coimmunoprecipitation with phosphorylated CREB (p-CREB) in a temporally defined manner from nuclear extracts. When CREB, CBP, and C/EBPbeta levels were knocked down by small interfering RNA, reductions in any of these transcription factors reduced cAMP-enhanced GnRH-II promoter activity and GnRH-II mRNA levels in JEG-3 and OVCAR-3 cells. Importantly, chromatin immunoprecipitation assay showed that p-CREB bound the CRE within the endogenous GnRH-II promoter within 1 h and that p-CREB association with C/EBPbeta occurs within 2 h of cAMP stimulation, coincident with the first appearance of C/EBPbeta at the CRE. By contrast, maximum interactions between p-CREB and CBP do not occur until at least 4 h after cAMP stimulation, and this is reflected in the progressive loading of CBP at the CRE at 2-4 h, as demonstrated by chromatin immunoprecipitation. Taken together, these data suggest that p-CREB, C/EBPbeta, and CBP are recruited to the CRE of the GnRH-II promoter in a temporarily defined manner to enhance its transcription in JEG-3 and OVCAR-3 cells in response to cAMP.