Role of gonadotropin-releasing hormone (GnRH) in ovarian cancer

Lipid-Based Nanocarrier by Targeting with LHRH Peptide: A Promising Approach for Prostate Cancer Radio-Imaging and Therapy

Prostate cancer is a prevalently detected malignancy with a dismal prognosis. Luteinizing-hormone-releasing-hormone (LHRH) receptors are overexpressed in such cancer cells, to which the LHRH-decapeptide can specifically bind. A lipid-polyethylene glycol-conjugated new LHRH-decapeptide analogue (D-P-HLH) was synthesized and characterized. D-P-HLH-coated and anticancer drug doxorubicin (DX)-loaded solid lipid nanoparticles (F-DX-SLN) were formulated by the cold homogenization technique and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, differential scanning calorimetry, dynamic light scattering, electron microscopy, entrapment efficiency, and drug-release profile studies. F-DX-SLN allows site-specific DX delivery by reducing the side effects of chemotherapy. Cancer cells could precisely take up F-DX-SLN by targeting specific receptors, boosting the cytotoxicity at the tumor site. The efficacy of F-DX-SLN on PC3/SKBR3 cells by the MTT assay revealed that F-DX-SLN was more cytotoxic than DX and/or DX-SLN. Flow cytometry and confocal microscopic studies further support F-DX-SLNs' increased intracellular absorption capability in targeting LHRH overexpressed cancer cells. F-DX-SLN ensured high apoptotic potential, noticeably larger mitochondrial transmembrane depolarization action, as well as the activation of caspases, a longer half-life, and greater plasma concentration. F-DX-SLN/DX-SLN was radiolabeled with technetium-99m; scintigraphic imaging studies established its tumor selectivity in PC3 tumor-bearing nude mice. The efficacy of the formulations in cancer treatment, in vivo therapeutic efficacy tests, and histopathological studies were also conducted. Results clearly indicate that F-DX-SLN exhibits sustained and superior targeted administration of anticancer drugs, thus opening up the possibility of a drug delivery system with precise control and targeting effects. F-DX-SLN could also provide a nanotheranostic approach with improved efficacy for prostate cancer therapy.

Detailed survey of an in vitro intestinal epithelium model by single-cell transcriptomics

The co-culture of two adult human colorectal cancer cell lines, Caco-2 and HT29, on Transwell is commonly used as an in vitro gut mimic, yet the translatability of insights from such a system to adult human physiological contexts is not fully characterized. Here, we used single-cell RNA sequencing on the co-culture to obtain a detailed survey of cell type heterogeneity in the system and conducted a holistic comparison with human physiology. We identified the intestinal stem cell-, transit amplifying-, enterocyte-, goblet cell-, and enteroendocrine-like cells in the system. In general, the co-culture was fetal intestine-like, with less variety of gene expression compared to the adult human gut. Transporters for major types of nutrients were found in the majority of the enterocytes-like cells in the system. TLR 4 was not expressed in the sample, indicating that the co-culture model is incapable of mimicking the innate immune aspect of the human epithelium.

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.

Leuprolide Protects Ovarian Reserve in Adolescents Undergoing Gonadotoxic Therapy

Purpose: Treatment sequelae compromising reproductive health are highly prevalent in childhood cancer survivors, and a main determinant of health and quality of life. Follicular reserve determines ovarian function life span; thus, its preservation is important in the care of female survivors. Anti-Müllerian hormone (AMH) is a biomarker to measure functional ovarian reserve. We aimed to evaluate the effect of leuprolide during gonadotoxic therapy on pubertal females' post-treatment functional ovarian reserve using AMH levels. Methods: We conducted a single-center retrospective study including all pubertal females who had undergone gonadotoxic treatments between January 2010 and April 2020, and had an AMH level after completion of therapy. We used multivariable linear regressions to compare AMH-level beta coefficients in patients stratified by gonadotoxic risk, adjusting for leuprolide use. Results: Fifty-two females meeting study eligibility were included, of which 35 received leuprolide. The use of leuprolide was associated with higher post-treatment AMH levels in the lower gonadotoxic risk group (beta 2.74, 95% CI 0.97-4.51; p = 0.004). This association was lost in the higher gonadotoxic risk groups. Conclusions: Leuprolide may have a protective effect on the functional ovarian reserve. However, this is limited by increasing treatment gonadotoxicity. Larger, prospective studies are needed to elucidate the potential benefits of gonadotropin-releasing hormone agonist on preservation of ovarian reserve among children receiving gonadotoxic therapies, as cancer survivors.

The role of GnRH metabolite, GnRH-(1-5), in endometrial cancer

From the time of its discovery and isolation in the mammalian hypothalamus, the decapeptide, gonadotropin-releasing hormone (GnRH), has also been found to be expressed in non-hypothalamic tissues and can elicit a diverse array of functions both in the brain and periphery. In cancer, past studies have targeted the gonadotropin-releasing hormone receptors (GnRHR) as a way to treat reproductive cancers due to its anti-tumorigenic effects. On the contrary, its metabolite, GnRH-(1-5), behaves divergently from its parental peptide through putative orphan G-protein coupled receptor (oGPCR), GPR101. In this review, we will focus on the potential roles of GnRH-(1-5) in the periphery with an emphasis on its effects on endometrial cancer progression.

Predicting anticancer hyperfoods with graph convolutional networks

Background

Recent efforts in the field of nutritional science have allowed the discovery of disease-beating molecules within foods based on the commonality of bioactive food molecules to FDA-approved drugs. The pioneering work in this field used an unsupervised network propagation algorithm to learn the systemic-wide effect on the human interactome of 1962 FDA-approved drugs and a supervised algorithm to predict anticancer therapeutics using the learned representations. Then, a set of bioactive molecules within foods was fed into the model, which predicted molecules with cancer-beating potential.The employed methodology consisted of disjoint unsupervised feature generation and classification tasks, which can result in sub-optimal learned drug representations with respect to the classification task. Additionally, due to the disjoint nature of the tasks, the employed approach proved cumbersome to optimize, requiring testing of thousands of hyperparameter combinations and significant computational resources.To overcome the technical limitations highlighted above, we represent each drug as a graph (human interactome) with its targets as binary node features on the graph and formulate the problem as a graph classification task. To solve this task, inspired by the success of graph neural networks in graph classification problems, we use an end-to-end graph neural network model operating directly on the graphs, which learns drug representations to optimize model performance in the prediction of anticancer therapeutics.

Results

The proposed model outperforms the baseline approach in the anticancer therapeutic prediction task, achieving an F1 score of 67.99%±2.52% and an AUPR of 73.91%±3.49%. It is also shown that the model is able to capture knowledge of biological pathways to predict anticancer molecules based on the molecules’ effects on cancer-related pathways.

Conclusions

We introduce an end-to-end graph convolutional model to predict cancer-beating molecules within food. The introduced model outperforms the existing baseline approach, and shows interpretability, paving the way to the future of a personalized nutritional science approach allowing the development of nutrition strategies for cancer prevention and/or therapeutics.

Supplementary Information

The online version contains supplementary material available at (10.1186/s40246-021-00333-4).

Fertility Preservation in Female Pediatric Patients With Cancer: A Clinical and Regulatory Issue

Fertility preservation represents one important goal of cancer patients’ management due to the high impact on health and quality of life of survivors. The available preventive measures cannot be performed in all patients and are not feasible in all health-care facilities. Therefore, the pharmacological treatment with GnRHa has become a valuable non-invasive and well-tolerated alternative, especially in those who cannot access to cryopreservation options due to clinical and/or logistic issues. Supporting data demonstrate a significant advantage for the survivors who received GnRHa in the long-term maintenance of ovarian function and preservation of fertility. The prevention of the risk of ovarian failure with GnRHa is a typical off-label use, defined as the administration of a medicinal product not in accordance with the authorized product information. Italy has officially recognized the off-label use of GnRHa in adult women at risk of premature and permanent menopause following chemotherapy. However, fertility preservation still represents an unmet medical need in adolescents who cannot access to other treatment options.

The role of gonadotropin-releasing hormone agonists in female fertility preservation

Advances in anticancer treatments have resulted in increasing survival rates among cancer patients. Accordingly, the quality of life after treatment, particularly the preservation of fertility, has gradually emerged as an essential consideration. Cryopreservation of embryos or unfertilized oocytes has been considered as the standard method of fertility preservation among young women facing gonadotoxic chemotherapy. Other methods, including ovarian suppression and ovarian tissue cryopreservation, have been considered experimental. Recent large-scale randomized controlled trials have demonstrated that temporary ovarian suppression using gonadotropin-releasing hormone agonists (GnRHa) during chemotherapy is beneficial for preventing chemotherapy-induced premature ovarian insufficiency in breast cancer patients. It should also be emphasized that GnRHa use during chemotherapy does not replace established fertility preservation methods. All young women facing gonadotoxic chemotherapy should be counseled about and offered various options for fertility preservation, including both GnRHa use and cryopreservation of embryos, oocytes, and/or ovarian tissue.

Characterizing Endocrine Status, Tumor Hypoxia and Immunogenicity for Therapy Success in Epithelial Ovarian Cancer

Epithelial ovarian cancer is predominantly diagnosed at advanced stages which creates significant therapeutic challenges. As a result, the 5-year survival rate is low. Within ovarian cancer, significant tumor heterogeneity exists, and the tumor microenvironment is diverse. Tumor heterogeneity leads to diversity in therapy response within the tumor, which can lead to resistance or recurrence. Advancements in therapy development and tumor profiling have initiated a shift from a "one-size-fits-all" approach towards precision patient-based therapies. Here, we review aspects of ovarian tumor heterogeneity that facilitate tumorigenesis and contribute to treatment failure. These tumor characteristics should be considered when designing novel therapies or characterizing mechanisms of treatment resistance. Individual patients vary considerably in terms of age, fertility and contraceptive use which innately affects the endocrine milieu in the ovary. Similarly, individual tumors differ significantly in their immune profile, which can impact the efficacy of immunotherapies. Tumor size, presence of malignant ascites and vascular density further alters the tumor microenvironment, creating areas of significant hypoxia that is notorious for increasing tumorigenesis, resistance to standard of care therapies and promoting stemness and metastases. We further expand on strategies aimed at improving oxygenation status in tumors to dampen downstream effects of hypoxia and set the stage for better response to therapy.

Gonadotropin-Releasing Hormone Receptors in Prostate Cancer: Molecular Aspects and Biological Functions

Pituitary Gonadotropin-Releasing Hormone receptors (GnRH-R) mediate the activity of the hypothalamic decapeptide GnRH, thus playing a key role in the regulation of the reproductive axis. Early-stage prostate cancer (PCa) is dependent on serum androgen levels, and androgen-deprivation therapy (ADT), based on GnRH agonists and antagonists, represents the standard therapeutic approach for PCa patients. Unfortunately, the tumor often progresses towards the more aggressive castration-resistant prostate cancer (CRPC) stage. GnRH receptors are also expressed in CRPC tissues, where their binding to both GnRH agonists and antagonists is associated with significant antiproliferative/proapoptotic, antimetastatic and antiangiogenic effects, mediated by the Gαi/cAMP signaling cascade. GnRH agonists and antagonists are now considered as an effective therapeutic strategy for CRPC patients with many clinical trials demonstrating that the combined use of these drugs with standard therapies (i.e., docetaxel, enzalutamide, abiraterone) significantly improves disease-free survival. In this context, GnRH-based bioconjugates (cytotoxic drugs covalently linked to a GnRH-based decapeptide) have been recently developed. The rationale of this treatment is that the GnRH peptide selectively binds to its receptors, delivering the cytotoxic drug to CRPC cells while sparing nontumor cells. Some of these compounds have already entered clinical trials.

The direct effects of gonadotropin-releasing hormone on proliferation of granulosa cells and development of follicles in goose

1. The study objectives were to determine the direct effects of gonadotropin-releasing hormone (GnRH) on the proliferation of ovarian granulosa cells (GCs) and the development of follicles in geese (Anser cygnoides) by colorimetry and ethynyl-2'-deoxyuridine (EdU) cell proliferation assays, in which primary GCs were treated with different concentrations of GnRH agonist (alarelin acetate) and an antagonist (cetrorelix acetate). Differently expressed genes (DEGs) were identified by RNA-sequencing and validated by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and Western blotting. 2. The EdU assays showed that the proliferation of GCs was affected by the GnRH agonist and antagonist in a dose-dependent manner. The effect of treatment on cell proliferation was statistically significant at the concentrations of 10^-5 mol/l alarelin and 1 mg/l cetrorelix acetate. A total of 134 DEGs (76 downregulated and 58 upregulated for alarelin treatment) and 226 DEGs (90 downregulated and 136 upregulated for cetrorelix) were identified by RNA-sequencing analysis, respectively. Enrichment analysis indicated that DEGs were enriched in the GO terms of cell-cell signalling and cell junctions. The pathways that regulate the development of follicles were identified, including the biological progress of cAMP accumulation, ovulation cycle and vasculature that are essential to follicular selection. 3. The results suggested that GnRH might directly regulate GC proliferation via autocrine or paracrine pathways related to cell junctions. In particular, it was confirmed that the mRNA and protein expression levels of the oestrogen receptor 2 (ESR2) gene, a negative transcription factor involved in follicular maturation and ovulation, were affected by GnRH agonist or antagonist in GCs. 4. In conclusion, GnRH might play an important role in follicular development by changing the expression of genes that participate in cAMP accumulation, ovulation cycle and cell junctions in ovarian GCs.

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.

Fertility Preservation Using GnRH Agonists: Rationale, Possible Mechanisms, and Explanation of Controversy

The only clinically accepted method of fertility preservation in young women facing gonadotoxic chemo- and/or radiotherapy for malignant or autoimmune diseases is cryopreservation of embryos or unfertilized ova, whereas cryopreservation of ovarian tissue for future reimplantation, or in vitro maturation of follicles, and the use of gonadotropin-releasing hormone agonists (GnRHa) are still considered investigational, by several authorities. Whereas previous publications have raised the fear of GnRHa's possible detrimental effects in patients with hormone receptor-positive breast cancers, recent randomized controlled trials (RCTs) have shown that it either improves or does not affect disease-free survival (DFS) in such patients. This review summarizes the pros and cons of GnRHa co-treatment for fertility preservation, suggesting 5 theoretical mechanisms for GnRHa action: (1) simulating the prepubertal hypogonadotropic milieu, (2) direct effect on GnRH receptors, (3) decreased ovarian perfusion, (4) upregulation of an ovarian-protecting molecule such as sphingosine-1-phosphate, and (5) protecting a possible germinative stem cell. We try to explain the reasons for the discrepancy between most publications that support the use of GnRHa for fertility preservation and the minority of publications that did not support its efficiency.

Ovarian protection with gonadotropin-releasing hormone agonists during chemotherapy in cancer patients: From biological evidence to clinical application

Survivorship issues are an area of crucial importance to be addressed as early as possible by all health care providers dealing with cancer patients. In women diagnosed during their reproductive years, the possible occurrence of chemotherapy-induced premature ovarian insufficiency (POI) is of particular concern being associated with important menopause-related symptoms, psychosocial issues as well as infertility. Temporary ovarian suppression by administering a gonadotropin-releasing hormone agonist (GnRHa) during chemotherapy has been studied to reduce the gonadotoxic impact of chemotherapy thus diminishing the chance of developing POI. Despite more than 30 years of research in both preclinical and clinical settings, the performance of this strategy has remained highly debated until recently. In particular, the potential mechanisms of action for the protective effects of GnRHa during chemotherapy are still not clearly identified. Nevertheless, important novel research efforts in the field have better elucidated the role of this option that is now endorsed for clinical use by several guidelines. This manuscript aims at providing an extensive overview of the literature on the use of temporary ovarian suppression with GnRHa during chemotherapy in cancer patients by addressing its biological rationale, the available preclinical and clinical evidence as well as the still existing grey zones in this field that future research efforts should address.

Inhibition of RM-1 prostate carcinoma and eliciting robust immune responses in the mouse model by using VEGF-M2-GnRH3-hinge-MVP vaccine

GnRH and VEGF have been investigated as prostate carcinoma enhancers that support tumor spread and progression. Although both have documented roles in prostate carcinoma and many cancer types, the weak immunogenicity of these peptides has remained a major challenge for use in immunotherapy. Here, we describe a novel strategy to inhibit GnRH and VEGF production and assess the effect on the immune responses against these hormones using the RM-1 prostate cancer model. We designed a novel recombinant fusion protein which combined GnRH and VEGF as a vaccine against this tumor. The newly constructed fusion protein hVEGF121-M2-GnRH3-hinge-MVP contains the human vascular endothelial growth factor (hVEGF121) and three copies of GnRH in sequential linear alignment and T helper epitope MVP as an immunogenic vaccine. The effectiveness of the vaccine in eliciting an immune response and attenuating the prostate tumor growth was evaluated. Results showed that administration of a new vaccine effectively elicited humoral and cellular immune responses. We found that, a novel fusion protein, hVEGF121-M2-GnRH3-hinge-MVP, effectively inhibited growth of RM-1 prostate model and effectively promoted immune response. In conclusion, hVEGF121-M2-GnRH3-hinge-MVP is an effective dual mechanism tumor vaccine that limits RM-1 prostate growth. This vaccine may be a promising strategy for the treatment of hormone refractory prostate malignancies.

Female fertility preservation in the pediatric and adolescent cancer patient population

The 5-year survival rate for childhood cancer is over 80%, thereby increasing the number of young women facing infertility in the future because of the gonadotoxic effects of chemotherapy and radiation. The gonadotoxic effects of childhood cancer treatment vary by the radiation regimen and the chemotherapeutic drugs utilized. Although the American Society of Clinical Oncology guidelines recommend fertility preservation for all patients, there are several barriers and ethical considerations to fertility preservation in the pediatric and adolescent female population. Additionally, the fertility preservation methods for pre- and postpubertal females differ, with only experimental methods available for prepubertal females. We will review the risk of chemotherapy and radiation on female fertility, the approach to fertility preservation in the pediatric and adolescent female population, methods of fertility preservation for both pre- and postpubertal females, barriers to fertility preservation, cost, and psychological and ethical considerations.

Knockdown of Hepatic Gonadotropin-Releasing Hormone by Vivo-Morpholino Decreases Liver Fibrosis in Multidrug Resistance Gene 2 Knockout Mice by Down-Regulation of miR-200b

Hepatic fibrosis occurs during the progression of primary sclerosing cholangitis (PSC) and is characterized by accumulation of extracellular matrix proteins. Proliferating cholangiocytes and activated hepatic stellate cells (HSCs) participate in the promotion of liver fibrosis during cholestasis. Gonadotropin-releasing hormone (GnRH) is a trophic peptide hormone synthesized by hypothalamic neurons and the biliary epithelium and exerts its biological effects on cholangiocytes by interaction with the receptor subtype (GnRHR1) expressed by cholangiocytes and HSCs. Previously, we demonstrated that administration of GnRH to normal rats increased intrahepatic biliary mass (IBDM) and hepatic fibrosis. Also, miR-200b is associated with the progression of hepatic fibrosis; however, the role of the GnRH/GnRHR1/miR-200b axis in the development of hepatic fibrosis in PSC is unknown. Herein, using the mouse model of PSC (multidrug resistance gene 2 knockout), the hepatic knockdown of GnRH decreased IBDM and liver fibrosis. In vivo and in vitro administration of GnRH increased the expression of miR-200b and fibrosis markers. The GnRH/GnRHR1 axis and miR-200b were up-regulated in human PSC samples. Cetrorelix, a GnRHR1 antagonist, inhibited the expression of fibrotic genes in vitro and decreased IBDM and hepatic fibrosis in vivo. Inhibition of miR-200b decreased the expression of fibrosis genes in vitro in cholangiocyte and HSC lines. Targeting the GnRH/GnRHR1/miR-200b axis may be key for the management of hepatic fibrosis during the progression of PSC.

Pharmacotherapeutic Targeting of G Protein-Coupled Receptors in Oncology: Examples of Approved Therapies and Emerging Concepts

G protein-coupled receptors (GPCRs) are involved in numerous physio-pathological processes, including the stimulation of cancer progression. In this regard, it should be mentioned that although GPCRs may represent major pharmaceutical targets, only a few drugs acting as GPCR inhibitors are currently used in anti-tumor therapies. For instance, certain pro-malignancy effects mediated by GPCRs are actually counteracted by the use of small molecules and peptides that function as receptor antagonists or inverse agonists. Recently, humanized monoclonal antibodies targeting GPCRs have also been developed. Here, we review the current GPCR-targeted therapies for cancer treatment, summarizing the clinical studies that led to their official approval. We provide a broad overview of the mechanisms of action of the available anti-cancer drugs targeting gonadotropin-releasing hormone, somatostatin, chemokine, and Smoothened receptors. In addition, we discuss the anti-tumor potential of novel non-approved molecules and antibodies able to target some of the aforementioned GPCRs in different experimental models and clinical trials. Likewise, we focus on the repurposing in cancer patients of non-oncological GPCR-based drugs, elucidating the rationale behind this approach and providing clinical evidence on their safety and efficacy.

Applying Multivariate Adaptive Splines to Identify Genes With Expressions Varying After Diagnosis in Microarray Experiments

PURPOSE

To analyze a microarray experiment to identify the genes with expressions varying after the diagnosis of breast cancer.

METHODS

A total of 44 928 probe sets in an Affymetrix microarray data publicly available on Gene Expression Omnibus from 249 patients with breast cancer were analyzed by the nonparametric multivariate adaptive splines. Then, the identified genes with turning points were grouped by K-means clustering, and their network relationship was subsequently analyzed by the Ingenuity Pathway Analysis.

RESULTS

In total, 1640 probe sets (genes) were reliably identified to have turning points along with the age at diagnosis in their expression profiling, of which 927 expressed lower after turning points and 713 expressed higher after the turning points. K-means clustered them into 3 groups with turning points centering at 54, 62.5, and 72, respectively. The pathway analysis showed that the identified genes were actively involved in various cancer-related functions or networks.

CONCLUSIONS

In this article, we applied the nonparametric multivariate adaptive splines method to a publicly available gene expression data and successfully identified genes with expressions varying before and after breast cancer diagnosis.

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.

LHRH-Targeted Drug Delivery Systems for Cancer Therapy

Targeted delivery of therapeutic and diagnostic agents to cancer sites has significant potential to improve the therapeutic outcome of treatment while minimizing severe side effects. It is widely accepted that decoration of the drug delivery systems with targeting ligands that bind specifically to the receptors on the cancer cells is a promising strategy that may substantially enhance accumulation of anticancer agents in the tumors. Due to the transformed cellular nature, cancer cells exhibit a variety of overexpressed cell surface receptors for peptides, hormones, and essential nutrients, providing a significant number of target candidates for selective drug delivery. Among others, luteinizing hormonereleasing hormone (LHRH) receptors are overexpressed in the majority of cancers, while their expression in healthy tissues, apart from pituitary cells, is limited. The recent studies indicate that LHRH peptides can be employed to efficiently guide anticancer and imaging agents directly to cancerous cells, thereby increasing the amount of these substances in tumor tissue and preventing normal cells from unnecessary exposure. This manuscript provides an overview of the targeted drug delivery platforms that take advantage of the LHRH receptors overexpression by cancer cells.

Glucose regulates the intrinsic inflammatory response of the heart to surgically induced hypothermic ischemic arrest and reperfusion

We investigated the isolated working rat heart as a model to study early transcriptional remodeling induced in the setting of open heart surgery and stress hyperglycemia. Hearts of male Sprague Dawley rats were cold-arrested in Krebs-Henseleit buffer and subjected to 60 min normothermic reperfusion in the working mode with buffer supplemented with noncarbohydrate substrates plus glucose (25 mM) or mannitol (25 mM; osmotic control). Gene expression profiles were determined by microarray analysis and compared with those of nonperfused hearts. Perfused hearts displayed a transcriptional signature independent from the presence of glucose showing a more than twofold increase in expression of 71 genes connected to inflammation, cell proliferation, and apoptosis. These transcriptional alterations were very similar to the ones taking place in the hearts of open heart surgery patients. Prominent among those alterations was the upregulation of the three master regulators of metabolic reprogramming, MYC, NR4A1, and NR4A2. Targeted pathway analysis revealed an upregulation of metabolic processes associated with the proliferation and activation of macrophages and fibroblasts. Glucose potentiated the upregulation of a subset of genes associated with polarization of tissue reparative M2-like macrophages, an effect that was lost in perfused hearts from rats rendered insulin resistant by high-sucrose feeding. The results expose the heart as a significant source of proinflammatory mediators released in response to stress associated with cardiac surgery with cardiopulmonary bypass, and suggest a major role for glucose as a signal in the determination of resident cardiac macrophage polarization.

Gonadotropin-releasing hormone analog therapy for central precocious puberty and other childhood disorders affecting growth and puberty

Gonadotropin-releasing hormone (GnRH) analog therapy relies primarily on the ability of these compounds to bind to and modulate GnRH-receptor activity. GnRH analogs have been used in pediatric patients where endogenous gonadotropin release is undesirable or potentially harmful, such as in: (i) patients with central precocious puberty (CPP); (ii) healthy short children where pubertal delay would provide an opportunity to supplement pre-pubertal linear growth; and (iii) children with malignancies and other disorders where treatment requires the use of gonadotoxic compounds. In the first two groups of patients, GnRH agonists may be used alone or in conjunction with somatropin (growth hormone [GH]) to prevent early skeletal maturation and increase the subsequent adult height, while in the latter case, GnRH agonists are used alone or in conjunction with GnRH antagonists in an attempt to preserve gonadal function.In children and adolescents with CPP, timely use of GnRH agonists alone can result in an adult height within the genetic potential of the individual (target height); however, minimal height is gained when GnRH agonist therapy is commenced after a marked advancement of skeletal age. This provides the rationale for combined therapy with GnRH agonists and somatropin in such patients, and studies have shown improved growth with this approach compared with GnRH agonists alone. Combination therapy with GnRH agonists and somatropin has also been shown to increase adult heights to a greater extent than GnRH agonists alone in pediatric patients with concomitant CPP and GH deficiency, those with idiopathic short stature, and those born small for gestational age; however, such combination therapy has shown no increased benefit over somatropin alone in pediatric patients with GH deficiency. Limited results in children and adolescents with congenital adrenal hyperplasia and chronic primary hypothyroidism have also shown increased growth rates, while no growth benefit was seen in pediatric renal transplant recipients.GnRH analogs also have potential as gonadoprotective agents; studies of GnRH agonists used alone and in combination with GnRH antagonists in women undergoing cytotoxic therapy have shown increased preservation of reproductive potential in patients who were receiving GnRH analog therapy versus those who were not.The adverse effects of GnRH analogs mainly consist of menopausal-like complaints. Increases in bodyweight and body mass index in children receiving GnRH agonist therapy have been shown; however, these increases do not persist after discontinuation of therapy. Adult bone mineral density and fertility are also not adversely affected by childhood GnRH agonist therapy.GnRH analog therapy appears to be both well tolerated and effective in pediatric patients, as it allows the preservation or improvement of adult height, and shows no longstanding negative effects on body composition, bone density, reproductive function, or endocrine physiology. These agents may also be useful for preservation of gonadal function in children and adolescents undergoing cytotoxic therapy.

Hormone Receptors in Serous Ovarian Carcinoma: Prognosis, Pathogenesis, and Treatment Considerations

A few breakthroughs have been accomplished for the treatment of ovarian cancer, the most deadly gynecologic carcinoma, in the current era of targeted oncologic treatment. The estrogen receptor was the first target of such treatments with the introduction of tamoxifen four decades ago in breast cancer therapeutics. Attempts to duplicate the success of hormonal therapies in ovarian cancer met with mixed results, which may be due to an inferior degree of hormone dependency in this cancer. Alternatively, this may be due to the failure to clearly identify the subsets of ovarian cancer with hormone sensitivity. This article reviews the expression of hormone receptors by ovarian cancer cells, the prognostic value of these expressions, and their predictive capacity for response to hormonal agents. The possible ways ahead are briefly discussed.

GnRH and GnRH receptors in the pathophysiology of the human female reproductive system

BACKGROUND

Human reproduction depends on an intact hypothalamic-pituitary-gonadal (HPG) axis. Hypothalamic gonadotrophin-releasing hormone (GnRH) has been recognized, since its identification in 1971, as the central regulator of the production and release of the pituitary gonadotrophins that, in turn, regulate the gonadal functions and the production of sex steroids. The characteristic peculiar development, distribution and episodic activity of GnRH-producing neurons have solicited an interdisciplinary interest on the etiopathogenesis of several reproductive diseases. The more recent identification of a GnRH/GnRH receptor (GnRHR) system in both the human endometrium and ovary has widened the spectrum of action of the peptide and of its analogues beyond its hypothalamic function.

METHODS

An analysis of research and review articles published in international journals until June 2015 has been carried out to comprehensively summarize both the well established and the most recent knowledge on the physiopathology of the GnRH system in the central and peripheral control of female reproductive functions and diseases.

RESULTS

This review focuses on the role of GnRH neurons in the control of the reproductive axis. New knowledge is accumulating on the genetic programme that drives GnRH neuron development to ameliorate the diagnosis and treatment of GnRH deficiency and consequent delayed or absent puberty. Moreover, a better understanding of the mechanisms controlling the episodic release of GnRH during the onset of puberty and the ovulatory cycle has enabled the pharmacological use of GnRH itself or its synthetic analogues (agonists and antagonists) to either stimulate or to block the gonadotrophin secretion and modulate the functions of the reproductive axis in several reproductive diseases and in assisted reproduction technology. Several inputs from other neuronal populations, as well as metabolic, somatic and age-related signals, may greatly affect the functions of the GnRH pulse generator during the female lifespan; their modulation may offer new possible strategies for diagnostic and therapeutic interventions. A GnRH/GnRHR system is also expressed in female reproductive tissues (e.g. endometrium and ovary), both in normal and pathological conditions. The expression of this system in the human endometrium and ovary supports its physiological regulatory role in the processes of trophoblast invasion of the maternal endometrium and embryo implantation as well as of follicular development and corpus luteum functions. The GnRH/GnRHR system that is expressed in diseased tissues of the female reproductive tract (both benign and malignant) is at present considered an effective molecular target for the development of novel therapeutic approaches for these pathologies. GnRH agonists are also considered as a promising therapeutic approach to counteract ovarian failure in young female patients undergoing chemotherapy.

CONCLUSIONS

Increasing knowledge about the regulation of GnRH pulsatile release, as well as the therapeutic use of its analogues, offers interesting new perspectives in the diagnosis, treatment and outcome of female reproductive disorders, including tumoral and iatrogenic diseases.

Protecting Ovaries During Chemotherapy Through Gonad Suppression: A Systematic Review and Meta-analysis

OBJECTIVE

To estimate whether gonadotropin-releasing hormone (GnRH) analog administration during chemotherapy can protect against development of ovarian toxicity.

DATA SOURCES

MEDLINE (1966 to present), EMBASE (1980 to present), Cochrane Central Register of Controlled Trials (CENTRAL), World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov were searched through March 2015 using the phrases: "gonadotropin-releasing hormone," "chemotherapy," and "premature ovarian failure." Hand-search on conference abstracts, SCOPUS, and ISI Web of Science were also searched.

METHODS OF STUDY SELECTION

Published English-language randomized controlled trials comparing resumption of ovarian function between GnRH analogs plus chemotherapy with chemotherapy without GnRH analogs were included. Studies including women with pelvic metastases or recent history of receiving chemotherapy were excluded. Accordingly, 10 eligible trials (907 women) were analyzed.

TABULATION, INTEGRATION, AND RESULTS

Our primary outcome was the proportion of women with resumed ovarian function (defined as resumption of menstruation, prevention of chemotherapy-induced ovarian failure, or both) at the longest follow-up after the end of chemotherapy. Secondary outcomes were evaluating ovarian reserve parameters and pregnancy. Risk ratio was used to integrate qualitative results and mean difference was used for quantitative data. Gonadotropin-releasing hormone analog cotreatment did not significantly increase ovarian function resumption (320/468 [68.4%] in GnRH analog arm and 263/439 [59.9%] in the chemotherapy alone arm; risk ratio 1.12, 95% confidence interval [CI] 0.99-1.27). No protective effect existed after subgroup analyses (type of malignancy [P=.31], age [P=.14], and GnRH analog type [P=.44]). Gonadotropin-releasing hormone analogs did not protect any of ovarian reserve parameters, whether follicle-stimulating hormone (mean difference -2.63, 95% CI -7.33 to 2.07), antral follicle count (mean difference 1.66, 95% CI -0.69 to 4.01), or anti-Müllerian hormone (mean difference 0.31, 95% CI -0.41 to 1.03). Spontaneous pregnancy was also comparable (risk ratio 1.63, 95% CI 0.94-2.82).

CONCLUSION

Gonadotropin-releasing hormone analog administration during chemotherapy does not appear to protect the ovaries from gonadal toxicity. It is not a reliable method for fertility preservation.

Gonadotropin‑releasing hormone inhibits the proliferation and motility of nasopharyngeal carcinoma cells

Gonadotropin-releasing hormone (GnRH), or its analogues have been demonstrated to exhibit anti-proliferative effects on tumour cells in ovarian, endometrial and breast cancer through GnRH-receptors (GnRH-R). However, the role of GnRH in nasopharyngeal carcinoma (NPC) remains to be elucidated. In order to investigate the effects of GnRH in NPC, the present study examined the expression of the GnRH-R transcript in NPC and investigated the phenotypic changes in HK1 cells, a recurrent NPC-derived cell line, upon receiving GnRH treatment. Firstly, the GnRH-R transcript was demonstrated in the NPC cell lines and four snap frozen biopsies using reverse transcription-quantitative polymerase chain reaction. In addition, immunohistochemistry revealed the expression of GnRH-R in two of the eight (25%) NPC specimens. Treatment with GnRH induced a rapid increase in intracellular ionised calcium concentration in the NPC cells. GnRH and its agonists, triptorelin and leuprolide, exerted anti-proliferative effects on the NPC cells, as determined using an MTS assay. GnRH did not induce any cell cycle arrest in the HK1 cells under the conditions assessed in the present study. Time-lapse imaging demonstrated a reduction in cell motility in the GnRH-treated cells. In conclusion, GnRH, or its analogues may have antitumour effects on NPC cells. The consequences of alterations in the levels of GnRH on the progression of NPC require further examination.

An approach to asymmetric synthesis of β-aryl alanines by Pd(0)-catalyzed cross-coupling and cyanate-to-isocyanate rearrangement

A new method for the asymmetric synthesis of β-aryl alanines is reported.

Introduction of D-phenylalanine enhanced the receptor binding affinities of gonadotropin-releasing hormone peptides

The purpose of this study was to examine whether the introduction of D-Phe could improve the GnRH receptor binding affinities of DOTA-conjugated D-Lys(6)-GnRH peptides. Building upon the construct of DOTA-Ahx-(D-Lys(6)-GnRH1) we previously reported, an aromatic amino acid of D-Phe was inserted either between the DOTA and Ahx or between the Ahx and D-Lys(6) to generate new DOTA-D-Phe-Ahx-(D-Lys(6)-GnRH) or DOTA-Ahx-D-Phe-(D-Lys(6)-GnRH) peptides. Compared to DOTA-Ahx-(D-Lys(6)-GnRH1) (36.1 nM), the introduction of D-Phe improved the GnRH receptor binding affinities of DOTA-D-Phe-Ahx-(D-Lys(6)-GnRH) (16.3 nM) and DOTA-Ahx-D-Phe-(D-Lys(6)-GnRH) (7.6 nM). The tumor targeting and pharmacokinetic properties of (111)In-DOTA-Ahx-D-Phe-(D-Lys(6)-GnRH) was determined in MDA-MB-231 human breast cancer-xenografted nude mice. Compared to (111)In-DOTA-Ahx-(D-Lys(6)-GnRH1), (111)In-DOTA-Ahx-D-Phe-(D-Lys(6)-GnRH) exhibited comparable tumor uptake with faster renal and liver clearance. The MDA-MB-231 human breast cancer-xenografted tumors were clearly visualized by single photon emission computed tomography (SPECT) using (111)In-DOTA-Ahx-D-Phe-(D-Lys(6)-GnRH) as an imaging probe, providing a new insight into the design of new GnRH peptides in the future.

Utility of GnRH-agonists for Fertility Preservation in Women With Operable Breast Cancer: Is It Protective?

Breast cancer is the most common type of malignancy in reproductive-age women. Breast cancer chemotherapy is associated with premature ovarian failure, infertility and negative psychosocial effects related to these reproductive changes. As a result of this, fertility preservation becomes highly critical in this group of women. Besides the fertility preservation methods that utilize assisted reproductive technologies such as embryo, oocyte, and ovarian tissue cryopreservation, another suggested strategy for fertility preservation is suppression of ovarian ovulatory function by gonadotropin-releasing hormone agonist (GnRHa) administration before and during chemotherapy. However, both the efficacy and safety of GnRH agonists for prevention of ovarian damage are unproven and the preponderance of evidence indicates that this is an ineffective strategy. This review details the most recent information and studies on this controversial topic.

Treatment of high risk Sertoli-Leydig cell tumors of the ovary using a gonadotropin releasing hormone (GnRH) analog

Sertoli-Leydig cell tumors are rare ovarian neoplasms. We report two unusual cases with bilateral SLCTs suggesting evidence of genetic predisposition and at high risk of recurrence. To reduce this risk, we exploited the use of GnRH analog to lower gondadotropin and potentially directly inhibit the tumors through expressed GnRH receptors. We used it as maintenance antitumor therapy for 2 years after completion of chemotherapy, to cover the period of risk for recurrence. Both patients remain in complete remission at >2 years after completing leuprorelin therapy. Of note, both patients carry DICER1 mutations, frequently found in pleuropulmonary blastoma syndrome.

GnRH-(1-5) transactivates EGFR in Ishikawa human endometrial cells via an orphan G protein-coupled receptor

The decapeptide GnRH is known for its central role in the regulation of the hypothalamo-pituitary-gonadal axis. In addition, it is also known to have local effects within peripheral tissues. The zinc metalloendopeptidase, EC 3.4.24.15 (EP24.15), can cleave GnRH at the Tyr(5)-Gly(6) bond to form the pentapeptide, GnRH-(1-5). The central and peripheral effect of GnRH-(1-5) is different from its parent peptide, GnRH. In the current study, we examined the effect of GnRH-(1-5) on epidermal growth factor receptor (EGFR) phosphorylation and cellular migration. Using the Ishikawa cell line as a model of endometrial cancer, we demonstrate that GnRH-(1-5) stimulates epidermal growth factor release, increases the phosphorylation of EGFR (P < .05) at three tyrosine sites (992, 1045, 1068), and promotes cellular migration. In addition, we also demonstrate that these actions of GnRH-(1-5) are mediated by the orphan G protein-coupled receptor 101 (GPR101). Down-regulation of GPR101 expression blocked the GnRH-(1-5)-mediated release of epidermal growth factor and the subsequent phosphorylation of EGFR and cellular migration. These results suggest that GPR101 is a critical requirement for GnRH-(1-5) transactivation of EGFR in Ishikawa cells.

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.

Preservation of ovarian function and fertility despite gonadotoxic chemotherapy

The author aims to review the various strategies and avenues for fertility preservation despite gonadotoxic chemotherapy in young women. The recent increase in the survival of young patients has increased the worldwide attempts toward fertility preservation. The currently utilized methods are sperm cryopreservation and banking in male patients, and cryopreservation of embryos, unfertilized oocytes and ovarian tissue, as well as administration of gonadotropin-releasing hormone agonists (GnRH-a) before and during the gonadotoxic chemotherapy in young female patients. For those patients in whom pelvic irradiation is planned, ovariopexy is suggested. Since none of the suggested methods are ideal and none guarantees future fertility, a combination of several methods may optimize patients' chance of fertility preservation. GnRH-a co-treatment may reduce ovarian damage significantly in female patients treated with gonadotoxic chemotherapy. GnRH-a should be considered for women of reproductive age receiving gonadotoxic chemotherapy in addition to assisted reproduction and cryopreservation of embryos, oocytes and ovarian tissue.

Differential expression of ribosomal protein gene, gonadotrophin releasing hormone gene and Balbiani ring protein gene in silver nanoparticles exposed Chironomus riparius

The eco- and genotoxicity of silver nanoparticles (AgNPs) was investigated in the fourth instar larvae of the aquatic midge, Chironomus riparius. AgNPs did not have acute toxicity in C. riparius, but did exhibited chronic toxicity on development (pupation and emergence failure) and reproduction. Genotoxicity also occurred in AgNPs exposed C. riparius. Differential Display PCR (DD-PCR), based on the Annealing Control Primer (ACP) technique, was conducted to investigate the underlying toxic mechanism, which identified altered gene expression in C. riparius after treatment with AgNPs. The possible toxicity mechanism of AgNPs in C. riparius involves the down regulation of the ribosomal protein gene (CrL15) affecting the ribosomal assembly and consequently, protein synthesis. Up regulation of the gonadotrophin releasing hormone gene (CrGnRH1) might lead to the activation of gonadotrophin releasing hormone mediated signal transduction pathways and reproductive failure. Up regulation of the Balbiani ring protein gene (CrBR2.2) may be an indication of the organism's protection mechanism against the AgNPs. The overall results suggest that the toxicity of AgNPs towards aquatic organisms should be thoroughly investigated to allow for their safe use, as they seem to exhibit important toxicity towards C. riparius.

N-acetyl cysteine: could it be an effective adjuvant therapy in ICSI cycles? A preliminary study

This randomized controlled trial tested the hypothesis that addition of N-acetyl cysteine (NAC) can increase the probability of pregnancy in intracytoplasmic sperm injection (ICSI) cycles using the long agonist protocol. Women undergoing ICSI cycles due to male factor were randomly assigned to receive either long protocol (group A, 38 women) or long protocol plus NAC (group B, 38 women). Clinical pregnancy was the primary outcome. Granulosa cell apoptosis, fertilization rate, number of grade-one embryos and ongoing pregnancy were the secondary outcomes. Clinical pregnancy rate was insignificantly higher in NAC group (52.6%) than control (47.4%). Early and late apoptosis were also insignificantly lower in group B than in group A. Irrespective of the used protocol, there was significant negative correlation between both early and late apoptosis and fertilization rate (both P<0.001) and the number of good-quality embryos (P=0.007 and P<0.001, respectively). Pregnant patients had significantly lower early and late apoptosis than those who didn't achieve pregnancy (P<0.001). In conclusion, NAC supplementation did not significantly increase the probability of pregnancy in ICSI cycles using long agonist protocol. It appears that granulosa cell apoptosis may be an important prognosticator for ICSI cycle outcome.

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.

Signaling by G-protein-coupled receptor (GPCR): studies on the GnRH receptor

Gonadotropin-releasing hormone (GnRH) is the first key hormone of reproduction. GnRH analogs are extensively used in in vitro fertilization, and treatment of sex hormone-dependent cancers, due to their ability to bring about 'chemical castration'. The interaction of GnRH with its cognate type I receptor (GnRHR) in pituitary gonadotropes results in the activation of Gq/G(11), phospholipase Cbeta (PLCbetaI), PLA(2), and PLD. Sequential activation of the phospholipases generates the second messengers inositol 1, 4, 5-trisphosphate (IP(3)), diacylglycerol (DAG), and arachidonic acid (AA), which are required for Ca(2+) mobilization, the activation of various protein kinase C isoforms (PKCs), and the production of prostaglandin (PG) and other metabolites of AA, respectively. PKC isoforms are the major mediators of the downstream activation of a number of mitogen-activated protein kinase (MAPK) cascades by GnRH, namely: extracellular signal-regulated kinase (ERK), jun-N-terminal kinase (JNK), and p38MAPK. The activated MAPKs phosphorylate both cytosolic and nuclear proteins to initiate the transcriptional activation of the gonadotropin subunit genes and the GnRHR. While Ca(2+) mobilization has been found to initiate rapid gonadotropin secretion, Ca(2+), together with various PKC isoforms, MAPKs and AA metabolites also serve as key nodes, in the GnRH-stimulated signaling network that enables the gonadotropes to decode GnRH pulse frequencies and translating that into differential gonadotropin synthesis and release. Even though pulsatility of GnRH is recognized as a major determinant for differential gonadotropin subunit gene expression and gonadotropin secretion very little is yet known about the signaling circuits governing GnRH action at the 'Systems Biology' level. Direct apoptotic and metastatic effects of GnRH analogs in gonadal steroid-dependent cancers expressing the GnRHR also seem to be mediated by the activation of the PKC/MAPK pathways. However, the mechanisms dictating life (pituitary) vs. death (cancer) decisions made by the same GnRHR remain elusive. Understanding these molecular mechanisms triggered by the GnRHR through biochemical and 'Systems Biology' approaches would provide the basis for the construction of the dynamic connectivity maps, which operate in the various cell types (endocrine, cancer, and immune system) targeted by GnRH. The connectivity maps will open a new vista for exploring the direct effects of GnRH analogs in tumors and the design of novel combined therapies for fertility control, reproductive disorders and cancers.

GnRH-analogues and oral contraceptives for fertility preservation in women during chemotherapy

BACKGROUND

For preserving fertility in women during chemotherapy, the character of invasive techniques, such as ovarian cryopreservation and other techniques, await further experience. Meanwhile, non-invasive techniques have attempted to minimize the gonadotoxic effect of chemotherapy, by using gonadotrophin-releasing hormone-analogues (GnRH-a) or oral contraceptives (OC).

METHODS

We performed a computerized MEDLINE search to identify articles published on fertility preservation using GnRH-a or OCs.

RESULTS

Nine human-controlled studies reported the use of GnRH-a and four reported the use of OCs in parallel to chemotherapy. All nine studies analysing the effect of GnRH-a found lower rates of premature ovarian failure (POF) in patients receiving GnRH-a compared with the controls. Summarizing the studies resulted in 11.1% incidence of POF in patients who received GnRH-a compared with 55.5% incidence in the controls. Evidence using the fertility preserving effect of OC is limited. Two studies showed lower POF rates in OC-treated patients. The summarized data revealed a POF rate of 13.2% in patients who received OCs compared with that of 29.8% in the controls.

CONCLUSIONS

The published clinical studies provide evidence, but do not prove statistically, that GnRH-a co-treatment reduces gonadotoxicity. Owing to the retrospective and non-randomized nature of most of the studies, definite conclusions concerning the reduction of POF by GnRH-a can still not be unequivocally drawn. As GnRH-a and OC have no serious side effects and as GnRH-a can even reduce chemotherapy-induced complications, such as severe menometrorrhagia, GnRH-a are considered by many clinicians as a clinically useful co-treatment in chemotherapy. The published clinical studies on OC also suggest a possible effect on the reduction of POF under certain conditions.

Effects of central administration of gonadotropin-releasing hormone agonists and antagonist on elevated plus-maze and social interaction behavior in rats

The correlation between neuronal mechanism of anxiety and neuroanatomic expression/neuromodulatory role of gonadotropin-releasing hormone (GnRH), points to a role of GnRH in the modulation of anxiety. Therefore, we investigated the influence of GnRH agonists and antagonist on the anxiety-like behavior of rats in the elevated plus-maze and social interaction tests. GnRH agonists, leuprolide [100 or 200 ng/rat, intracerebroventricularly (i.c.v.)] or 6-D-tryptophan luteinizing hormone-releasing hormone (400 ng/rat, i.c.v.), significantly increased percentage of open arms entries, time spent in open arms, and time spent in social interaction. The observed anxiolytic effect of these agents was comparable with diazepam (0.5-1.0 mg/kg, intraperitoneally). Treatment with a GnRH antagonist [pGlu-D-Phe-Trp-Ser-Tyr-D-Ala-Leu-Arg-Pro-Gly-NH2, (100 ng/rat, i.c.v.)], significantly reduced percentage of open arm indices and decreased time spent in social interaction, indicating an anxiogenic-like effect. Further, castrated rats exhibited anxiogenic-like behavior in these tests, which was significantly attenuated by leuprolide (200 ng/rat, i.c.v.) or 6-D-tryptophan luteinizing hormone-releasing hormone (400 ng/rat, i.c.v.), indicating the noninvolvement of peripheral sex hormone in their anxiolytic-like effect, at least in castrated rats. In conclusion, this study indicated a putative role of GnRH in the control of anxiety, and further adds to the importance of investigating the possible role of the hypothalamus-pituitary-gonadal axis in regulating the anxiety-related disorders arising out of hypothalamus-pituitary-adrenal axis dysregulation.

The gonadotropin-releasing hormone (GnRH) neuronal population is normal in size and distribution in GnRH-deficient and GnRH receptor-mutant hypogonadal mice

Hypothalamic GnRH neurons are essential for initiation and regulation of reproductive function. In addition to pituitary gonadotrope stimulation, activity of GnRH through its receptor (GnRHR) has been suggested to include autocrine regulation of the GnRH neuron. Two hypogonadal mouse strains, the Gnrh1 mutant (hpg) mice and Gnrhr mutant mice were used to investigate the potential role of GnRH signaling in the proper development and maintenance of GnRH neurons. Immunocytochemical analysis of heterozygous hpg mice revealed a GnRH neuron population that was normal in size and distribution, indicating no effect from reduced Gnrh1 gene dosage on the neurons themselves. To visualize GnRH neurons in homozygous GnRH-deficient hpg mice, heterozygous hpg mice were crossed with GnRH-green fluorescent protein (GFP) transgenic mice with targeted expression of the GFP reporter gene in GnRH neurons. Analysis of forebrains of homozygous hpg/GFP-positive mice immunostained for GFP revealed a normal population size and appropriate distribution of GnRH neurons in hpg mice, with immunoreactive neuronal processes present at the median eminence. Similarly, adult mice deficient in functional GnRHR possessed a full complement of GnRH neurons in the basal forebrain that was indistinguishable from the distribution of GnRH neurons in their wild-type counterparts. Moreover, hpg/GFP neurons retained the ability to generate spontaneous bursts of action potential firing activity, suggesting that GnRH peptide is not required for this function. These data establish that autocrine-paracrine GnRH-signaling is not a prerequisite for the developmental migration of GnRH neurons into the brain or for the projection of GnRH neurosecretory axons.

Gonadotropin-releasing hormone agonist decreases chemotherapy-induced gonadotoxicity and premature ovarian failure in young female patients with Hodgkin lymphoma

OBJECTIVE

To minimize the gonadotoxic effect of chemotherapy by the cotreatment with a GnRH agonistic analogue (GnRH-a).

DESIGN

Prospective nonrandomized study with concurrent and historical controls.

SETTING

University medical center.

PATIENT(S)

One hundred fifteen female patients with Hodgkin lymphoma (HL).

INTERVENTION(S)

Sixty-five patients received a monthly injection of GnRH-a, administered before starting chemotherapy until its conclusion, up to a maximum of 6 months. Thirty-five patients were treated with ABVD and 76 with a procarbazine-containing regimen. This group was compared with a control group of 46 women who were treated concurrently with similar chemotherapy (n = 26) without GnRH-a or were historical controls (n = 20).

MAIN OUTCOME MEASURE(S)

Cyclic ovarian function (COF) versus premature ovarian failure (POF).

RESULT(S)

The ovarian function could be determined in 111 patients. In the GnRH-a/chemotherapy group, 63 out of 65 patients resumed ovulation and regular menses (96.9 %), compared with 63% of the 46 control subjects. Twenty of the 22 patients in the BEACOPP/escalated BEACOPP/GnRH-a cotreatment resumed cyclic ovarian function versus 9 of the 14 in the chemotherapy-only group. All 17 MOPP/ABV/GnRH-a cotreated patients resumed COF versus 11 of the 22 in the chemotherapy-only group. There was no significant effect of the GnRH-a cotreatment regarding COF in the ABVD group. There were no significant differences in the cumulative doses of the various alkylating agents between the two groups.

CONCLUSION(S)

Cotreatment with GnRH-a may reduce ovarian damage significantly in female patients treated for HL and should be considered in addition to assisted reproduction for women in reproductive age receiving gonadotoxic chemotherapy.

How to preserve fertility in young women exposed to chemotherapy? The role of GnRH agonist cotreatment in addition to cryopreservation of embrya, oocytes, or ovaries

The possibilities to preserve fertility in women exposed to chemotherapy are: in vitro fertilization plus embryo cryopreservation, ovarian cryopreservation, unfertilized ova cryopreservation, and the administration of a gonadotropin-releasing hormone (GnRH) agonist. Because none of these methods is ideal, combination of several methods should be considered. Because the chances of preserving gonadal function following combined-modality treatment are significantly better for girls than for boys, simulation of a prepubertal milieu was applied only to women of reproductive age. The administration of GnRH agonists to women with Hodgkin's disease, breast cancer, and other malignancies, or to patients with lupus nephropathy, in parallel with chemotherapy, by others and by us, has demonstrated a significantly lower rate of premature ovarian failure in survivors than in nonrandomized controls. Several prospective, randomized studies are ongoing. A recent meta-analysis found that the administration of a GnRH agonist, in addition to chemotherapy, to patients with breast cancer was associated with less recurrence and superior survival. Several possibilities to explain the beneficial effect of GnRH agonists to minimize chemotherapy-associated gonadotoxicity are suggested: (a) The hypogonadotropic milieu decreases the number of primordial follicles entering the differentiation stage, which is more vulnerable to chemotherapy; (b) The hypoestrogenic state decreases ovarian perfusion and delivery of chemotherapy to the ovaries; (c) A direct effect of the GnRH agonist on the ovary occurs independently of the gonadotropin level; (d) GnRH agonists may upregulate an intragonadal antiapoptotic molecule such as sphingosine-1-phosphate; (e) The GnRH agonist may protect ovarian germline stem cells.

Differential role of gonadotropin-releasing hormone on human ovarian epithelial cancer cell invasion

Ovarian cancer is the most lethal of all gynecological cancers. Most deaths from ovarian cancer are due to widespread intraperitoneal metastases and malignant ascites. However, mechanisms of invasion in ovarian cancer remain poorly understood. In this study, we examined the effects of gonadotropin-releasing hormone (GnRH)-I (the classical mammalian GnRH), GnRH-II (a second form of GnRH), and GnRH receptor on invasion using two human ovarian carcinoma cell lines, OVCAR-3 and SKOV-3. Here we demonstrated that in OVCAR-3, GnRH-I and GnRH-II promoted cell invasion, whereas in SKOV-3, GnRH-I and GnRH-II inhibited cell invasion. Transfection of small interfering RNA to abrogate the gene expression of GnRH receptor reversed GnRH-I and GnRH-II-mediated invasion activities, suggesting that the same receptor, type I GnRH receptor, is essential for the effects of GnRH-I and GnRH-II in both OVCAR-3 and SKOV-3. Treatment of SKOV-3 cells with GnRH-I or GnRH-II resulted in a decrease in matrix metalloproteinase 2 but an increase in tissue inhibitor of metalloproteinase 2 secretions. In addition, we found that GnRH-I and GnRH-II interfered with activation of the phosphatidylinositol-3-kinase/AKT pathway that is well documented to stimulate proteolysis and invasion of ovarian cancer cells. Taken together, these observations suggest that GnRH-I and GnRH-II play key regulatory roles in ovarian tumor cell invasion and extracellular matrix degradation.

Hormonal therapy in ovarian cancer

Ovarian carcinoma continues to be the leading cause of death due to gynecological malignancy. Epidemiologic studies indicate that steroid hormones play roles in ovarian carcinogenesis. Gonadotropins, estrogen, and androgen may be causative factors, while gonadotropin-releasing hormone and progesterone may be protective factors in ovarian cancer pathogenesis. Experimental studies have shown that hormonal receptors are expressed in ovarian cancer cells and mediate the growth-stimulatory or growth-inhibitory effects of the hormones on these cells. Hormonal therapeutic agents have been evaluated in several clinical trials. Most of these trials were conducted in patients with recurrent or refractory ovarian cancer, with modest efficacy and few side effects. Better understanding of the mechanisms through which hormones affect cell growth may improve the efficacy of hormonal therapy. Molecular markers that can reliably predict major clinical outcomes should be investigated further in well-designed trials.

Human myometrium and leiomyomas express gonadotropin-releasing hormone 2 and gonadotropin-releasing hormone 2 receptor

OBJECTIVE

To determine the presence or absence of a second form of GnRH (GnRH2) and corresponding receptor (GnRHR2) in human uterine myometrium and leiomyomata.

DESIGN

Evaluation of human leiomyoma and patient-matched myometrium of differential mRNA and protein expression of GnRH2 and GnRHR2.

SETTING

University hospital.

PATIENT(S)

Eight women undergoing medically indicated hysterectomy for symptomatic fibroids.

INTERVENTION(S)

Microarray analysis, reverse-transcriptase polymerase chain reaction (RT-PCR), real-time RT-PCR, and immunohistochemistry.

MAIN OUTCOME MEASURE(S)

Expression of mRNA and protein in leiomyoma and patient-matched myometrium.

RESULT(S)

Microarray analysis demonstrated expression, and we confirmed the findings by RT-PCR. Real-time RT-PCR demonstrated equivalent expression of the genes in leiomyoma compared with patient-matched myometrium (0.99-fold for GnRH2 and 1.28-fold for GnRHR2). Immunohistochemistry confirmed the expression of GnRH2 protein in both leiomyoma and myometrium.

CONCLUSION(S)

A second form of GnRH and corresponding receptor exists in the fibroid and myometrium. We speculate that an autocrine loop exists. Our findings provide further evidence that GnRH agonists may interact directly with GnRH receptors present in uterine fibroids.