The gonadotropin-releasing hormone system: Perspectives from reproduction to cancer (Review)

Whole-Genome Comparative Copy Number Alteration Profiling between Malignant Pleural Mesothelioma and Asbestos-Induced Chronic Pleuritis

Malignant pleural mesothelioma (MPM) is rare and aggressive cancer. The most important risk factor for MPM is exposure to asbestos. In this study, we scanned the genomes of individuals MPM and asbestos-induced chronic pleuritis (AICP) to compare and determine copy number alterations (CNAs) between two asbestos-related diseases. We used high-resolution SNP arrays to compare CNA profiles between MPM (n = 55) and AICP (n = 18). DNAs extracted from pleural tissues in both groups. SNP array analysis revealed common losses at 1p, 3p, 6q, 9p, 13q, 14q, 15q, 16q, 22q and frequent gains at chromosomes 1, 3, 5, 7, 8, and 6p, 12q, 15q, 17p, 20q in MPMs (frequencies max 67%-min 30%; these alterations were not detected in AICPs. Besides detecting well-known MPM-associated CNAs, our high -resolution copy number profiling also detected comparatively rare CNAs for MPMs including losses like 9q33.3, 16q and gains of 1p, 1q, 3p, 3q, 6p, 7q, 15q, 12q, 17p, 20q at significant frequencies in the MPM cohort. We also observed Copy Number gains clustered on the NF2 locus in AICPs, whereas this region was commonly deleted in MPMs. According to this distinct genomic profiles between the two groups, AICPs genomes can be clearly distinguished from highly altered MPM genomes. Hence, we can suggest that SNP arrays can be used as a supporting diagnostic tool in terms of discriminating asbestos-related malignant disease such as MPM and benign pleural lesions, which can be challenging in most instances.

Bioinformatics identify the role of chordin-like 1 in thyroid cancer

The abnormal expression of chordin-like 1 (CHRDL1) is identified in many cancers, while the effect of CHRDL1 in thyroid cancer (THCA) remains unclear. The University of California Santa Cruz, Gene Expression Profiling Interactive Analysis, University of Alabama at Birmingham Cancer, and Gene Expression Omnibus database (GSE33570, GSE33630, and GSE60542) were used for determining the mRNA and methylation expression of CHRDL1 in tumor and normal tissues. Human Protein Atlas was used for exploring the protein expression level of CHRDL1. The genes correlated to CHRDL1 were assessed by cBioPortal database. The prognostic value of CHRDL1 was evaluated through Kaplan-Meier method, cox regression, and nomogram analysis. Kyoto Encyclopedia of Genes and Genomes, Gene Ontology, and gene set enrichment analysis were used for predicting potential function of CHRDL1. The relationship between CHRDL1 and immune cell infiltration was determined by Pearson method. The downregulated mRNA and protein expressions of CHRDL1 were identified in THCA through the analysis of data from The Cancer Genome Atlas, Gene Expression Omnibus, and Human Protein Atlas database. The survival analysis showed that the CHRDL1 expression significantly affected disease-free interval (DFI) and progression-free interval, and CHRDL1 was an independent predictor of DFI. Besides, we found that C-C motif chemokine ligand 21 could significantly affect DFI time when it was co-expressed with CHRDL1. Additionally, the function of CHRDL1 was enriched in cell migration, apoptosis, and immune cell receptor. The downregulated expression of CHRDL1 was observed in THCA and caused poor prognosis. CHRDL1 may be involved in signal pathway related to cancer development and immune response, which suggested it could be a potential biomarker.

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.

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.

MicroRNA-200 family governs ovarian inclusion cyst formation and mode of ovarian cancer spread

Epidemiologic and histopathologic findings and the laying hen model support the long-standing incessant ovulation hypothesis and cortical inclusion cyst involvement in sporadic ovarian cancer development. MicroRNA-200 (miR-200) family is highly expressed in ovarian cancer. Herewith, we show that ovarian surface epithelial (OSE) cells with ectopic miR-200 expression formed stabilized cysts in three-dimensional (3D) organotypic culture with E-cadherin fragment expression and steroid hormone pathway activation, whereas ovarian cancer 3D cultures with miR-200 knockdown showed elevated TGF-β expression, mitotic spindle disorientation, increased lumenization, disruption of ROCK-mediated myosin II phosphorylation, and SRC signaling, which led to histotype-dependent loss of collective movement in tumor spread. Gene expression profiling revealed that epithelial-mesenchymal transition and hypoxia were the top enriched gene sets regulated by miR-200 in both OSE and ovarian cancer cells. The molecular changes uncovered by the in vitro studies were verified in both human and laying hen ovarian cysts and tumor specimens. As miR-200 is also essential for ovulation, our results of estrogen pathway activation in miR-200-expressing OSE cells add another intriguing link between incessant ovulation and ovarian carcinogenesis.

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.

Apoptotic Effects of Drug Targeting Conjugates Containing Different GnRH Analogs on Colon Carcinoma Cells

The wide range of cellular target reactions (e.g., antitumor) of gonadotropin-releasing hormone (GnRH) variants provides the possibility to develop multifunctional GnRH conjugates. The aim of our work was to compare the cytotoxic/apoptotic activity of different GnRH-based, daunorubicin (Dau)-linked conjugates with or without butyrated Lys in position 4 (⁴Lys(Bu)) at a molecular level in a human colorectal carcinoma cell line. Cell viability was measured by impedimetry, cellular uptake and apoptosis were studied by flow cytometry, and the expression of apoptosis-related genes was analyzed by qRT-PCR. The modification with ⁴Lys(Bu) resulted in an increased cytotoxic and apoptotic effects and cellular uptake of the GnRH-I and GnRH-III conjugates. Depending on the GnRH isoform and the presence of ⁴Lys(Bu), the conjugates could regulate the expression of several apoptosis-related genes, especially tumor necrosis factor (TNF), tumor protein p53 (TP53) and the members of growth-factor signaling. The stronger cytotoxicity of GnRH-I and GnRH-III conjugates containing ⁴Lys(Bu) was associated with a stronger inhibitory effect on the expression of growth-factor signaling elements in comparison with their ⁴Ser counterparts, in which the upregulation of TP53 and caspases (e.g., CASP9) seemed to play a more important role. We were able to provide further evidence that targeting the GnRH receptor could serve as a successful therapeutic approach in colon cancer, and GnRH-III-[⁴Lys(Bu),⁸Lys(Dau=Aoa)] proved to be the best candidate for this purpose.

Direct evidence on the efficacy of GnRH agonist in recurrent steroid cell tumor-not otherwise specified

Background

Steroid cell tumor (SCT) not otherwise specified (NOS) is rare and recurrence and metastasis rarely occurs; therefore, reports regarding its treatment are limited. We report a case of recurrent SCT-NOS treated with gonadotropin releasing hormone agonist (GnRHa) and successful.

Case

A 50-year-old woman underwent a staging laparotomy and diagnosed as SCT-NOS. Multiple liver tumors and intraperitoneal dissemination were detected 5 years 10 months after the initial surgery. As the immunohistochemical analysis showed positive staining for GnRH receptor, GnRHa was attempted. After the first cycle the serum testosterone level was normalized and after six cycles CT scan confirmed reduction of the tumor size.

Conclusion

Some ovarian SCT-NOS have GnRH receptors; thus, GnRHa may have a reducing effect for these tumors without major adverse event.

Subclinical Lipopolysaccharide from Salmonella Enteritidis Induces Dysregulation of Bioactive Substances from Selected Brain Sections and Glands of Neuroendocrine Axes

Bacterial lipopolysaccharide (LPS) can contribute to the pathogenesis and the clinical symptoms of many diseases such as cancer, mental disorders, neurodegenerative as well as metabolic diseases. The asymptomatic carrier state of Salmonella spp. is a very important public health problem. A subclinical single dose of LPS obtained from S. Enteritidis (5 μg/kg, i.v.) was administered to discern the consequences of changes of various brain peptides such as corticotropin-releasing hormone (CRH), gonadotropin-releasing hormone (GnRH), thyrotropin-releasing hormone (TRH), galanin (GAL), neuropeptide Y (NPY), somatostatin (SOM), substance P (SP), and vasoactive intestinal polypeptide (VIP) in selected clinically important brain sections and endocrine glands of the hypothalamic-pituitary-adrenal (HPA), -thyroid (HPT), -ovarian (HPO) axes. The study was conducted on ten immature crossbred female pigs. The brain peptides were extracted from the hypothalamus (medial basal hypothalamus, preoptic area, lateral hypothalamic area, mammillary bodies, and the stalk median eminence), and pituitary gland (adenohypophysis and neurohypophysis) sections and from the ovaries and adrenal and thyroid glands. There was no difference in health status between LPS and the control groups during the period of the experiment. Nevertheless, even a low single dose of LPS from S. Enteritidis that did not result in any clinical symptoms of disease induced dysregulation of various brain peptides, such as CRH, GnRH, TRH, GAL, NPY, SOM, SP, and VIP in selected brain sections of hypothalamus, pituitary gland and in the endocrine glands of the HPA, HPO, and HPT axes. In conclusion, the obtained results clearly show that subclinical LPS from S. Enteritidis can affect the brain chemistry structure and dysregulate bioactive substance from selected brain sections and glands of the neuroendocrine axes. The exact mechanisms by which LPS can influence major neuroendocrine axes are not fully understood and require further studies.

Differential roles of PKC isoforms (PKCs) in GnRH stimulation of MAPK phosphorylation in gonadotrope derived cells

The role of protein kinase C (PKC) isoforms (PKCs) in GnRH-stimulated MAPK [ERK1/2, JNK1/2 and p38) phosphorylation was examined in gonadotrope derived cells. GnRH induced a protracted activation of ERK1/2 and a slower and more transient activation of JNK1/2 and p38MAPK. Gonadotropes express conventional PKCα and PKCβII, novel PKCδ, PKCε and PKCθ, and atypical PKC-ι/λ. The use of green fluorescent protein (GFP)-PKCs constructs revealed that GnRH induced rapid translocation of PKCα and PKCβII to the plasma membrane, followed by their redistribution to the cytosol. PKCδ and PKCε localized to the cytoplasm and Golgi, followed by the rapid redistribution by GnRH of PKCδ to the perinuclear zone and of PKCε to the plasma membrane. The use of dominant negatives for PKCs and peptide inhibitors for the receptors for activated C kinase (RACKs) has revealed differential role for PKCα, PKCβII, PKCδ and PKCε in ERK1/2, JNK1/2 and p38MAPK phosphorylation in a ligand-and cell context-dependent manner. The paradoxical findings that PKCs activated by GnRH and PMA play a differential role in MAPKs phosphorylation may be explained by persistent vs. transient redistribution of selected PKCs or redistribution of a given PKC to the perinuclear zone vs. the plasma membrane. Thus, we have identified the PKCs involved in GnRH stimulated MAPKs phosphorylation in gonadotrope derived cells. Once activated, the MAPKs will mediate the transcription of the gonadotropin subunits and GnRH receptor genes.

Transcriptomic and epigenetic analysis of breast cancer stem cells

AIM

Cancer stem cells (CSCs) drive triple-negative breast cancer recurrence via their properties of self-renewal, invasiveness and radio/chemotherapy resistance. This study examined how CSCs might sustain these properties.

MATERIALS & METHODS

Transcriptomes, DNA methylomes and histone modifications were compared between CSCs and non CSCs.

RESULTS

Transcriptome analysis revealed several pathways that were activated in CSCs, whereas cell cycle regulation pathways were inhibited. Cell development and signaling genes were differentially methylated, with histone methylation analysis suggesting distinct H3K4me2 and H3K27me3 enrichment profiles. An integrated analysis revealed several tumor suppressor genes downregulated in CSCs.

CONCLUSION

Differential activation of various signaling pathways and genes contributes to the tumor-promoting properties of CSCs. Therapeutic targets identified in the analysis may contribute to improving treatment options for patients.

Activation of human gonadotropin-releasing hormone receptor promotes down regulation of ARHGAP18 and regulates the cell invasion of MDA-MB-231 cells

The Gonadotropin-Releasing Hormone Receptor (GnRHR) is expressed mainly in the gonadotrope membrane of the adenohypophysis and its natural ligand, the Gonadotropin-Releasing Hormone (GnRH), is produced in anterior hypothalamus. Furthermore, both molecules are also present in the membrane of cells derived from other reproductive tissues such as the breast, endometrium, ovary, and prostate, as well as in tumors derived from these tissues. The functions of GnRH receptor and its hormone in malignant cells have been related with the decrease of proliferation and the invasiveness of those tumors however, little is known about the molecules associated with the signaling pathways regulated by both molecules in malignant cells. To further analyze the potential mechanisms employed by the GnRHR/GnRH system to reduce the tumorigenesis of the highly invasive breast cancer cell line MDA-MB-231, we performed microarrays experiments to evaluated changes in genes expression and validate these modifications by functional assays. We show that activation of human GnRHR is able to diminish the expression and therefore functions of the Rho GTPase-Activating Protein 18 (ARHGAP18). Decrease of this GAP following GnRHR activation, correlates to the higher of cell adhesion and also with reduction of tumor cell invasion, supporting the notion that GnRHR triggers intracellular signaling pathways that acts through ARHGAP18. On the contrary, although a decline of cellular proliferation was observed during GnRHR activation in MDA-MB-231, this was independent of ARHGAP18 showing the complex system in which is involved the signaling pathways regulated by the GnRHR/GnRH system.

Goserelin promotes the apoptosis of epithelial ovarian cancer cells by upregulating forkhead box O1 through the PI3K/AKT signaling pathway

Gonadotropins, including luteinizing hormone (LH) and follicle stimulating hormone (FSH), are conducive to the growth of ovarian cancer based on the ‘gonadotropin theory’ and are regulated by gonadotropin-releasing hormone (GnRH). The present study was carried out to investigate the effect of goserelin, a GnRH agonist, on the apoptosis of epithelial ovarian cancer (EOC) cells and the underlying in vitro and in vivo mechanisms. Through flow cytometry, Hoechst staining and TUNEL staining, we demonstrated that goserelin promoted the apoptosis of EOC cells both in vitro and in vivo. Through human apoptosis gene PCR array, we verified that the promotion of EOC cell apoptosis by goserelin was linked to the upregulation of members of the tumor necrosis factor (TNF) and TNF receptor superfamilies, which have been identified as downstream targets of forkhead box O1 (FOXO1). Goserelin enhanced FOXO1 expression, and siRNA-mediated knockdown of FOXO1 abrogated the induction of apoptosis by goserelin. Moreover, goserelin decreased AKT activity, and FOXO1 upregulation by goserelin was dependent on the phosphatidylinositol 3-kinase (PI3K)/AKT pathway. In vivo, the expression of key factors in the PI3K/AKT/FOXO1 pathway was consistent with that observed in vitro. In conclusion, our data suggested that goserelin may promote EOC cell apoptosis by upregulating FOXO1 through the PI3K/AKT signaling pathway. We believe that GnRH agonists may be potential antitumor agents, and key factors in the PI3K/AKT-FOXO1 pathway may also be novel therapeutic targets for the treatment of EOC.

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.