Discovery of Small Molecule Agonist of Gonadotropin-Releasing Hormone Receptor (GnRH1R).

The gonadotrophin-releasing hormone (GnRH) is a central regulator of the human reproductive system and exerts physiological effects by binding to GnRH1R. The GnRH-GnRH1R system is a promising therapeutic target for the maintenance of reproductive function. There are several GnRH1R agonists on the market, but like GnRH, they are all peptide compounds and are limited by their way of administration (subcutaneous or intramuscular injection). To date, no published GnRH1R small molecule agonists have been reported. In this paper, the HTRF-based screening method has been used to screen our in-house chemical library, and we found and confirmed CD304 as a hit compound. Subsequently, structure optimization led to the discovery of compound 6d, exhibited with a certain GnRH1R activation activity (EC50: 1.59 ± 0.38 µM). Further molecular dynamics simulation experiments showed that 6d can well bind to the orthosteric site of GnRH1R through forming a hydrogen-bonding interaction with Y2836.51. Binding of 6d further induces conformational changes in TM6 and TM7, promoting the formation of a continuous water channel in GnRH1R, thereby promoting GnRH1R activation. This well-characterized hit compound will facilitate the further development of novel small molecule agonists of GnRH1R.

Transcriptomic evidence of luteinizing hormone-releasing hormone agonist (LHRH-A) regulation on lipid metabolism in grass carp (Ctenopharyngodon idella).

In this study, RNA sequencing was used to identify the hepatic gene expression profile in grass carp associated with luteinizing hormone-releasing hormone agonist (LHRH-A) treatment. A total of 93,912,172 reads were generated by HiSeq 4000 sequencing platform. After filtering, 83,450,860 clean reads were mapped to the reference genome. By calculating the FPKM of genes, 1475 differentially expressed genes were identified. PPAR signaling pathway was enriched with upregulated genes in LHRH-A injection group showing the regulation of the lipid metabolism by LHRH-A. The expression of eight key genes in PPAR signaling pathway was confirmed by qPCR and the results suggested that ACSL4A, ACSL4B, ANGPTL4, LPL, RXRBA and SLC27A1B were significantly stimulated by LHRH-A injection. This investigation provides the evidence that LHRH-A could play a role in lipid metabolism.

Efficacy and safety of ASP1707 for endometriosis-associated pelvic pain: the phase II randomized controlled TERRA study.

STUDY QUESTION: Does the GnRH antagonist, ASP1707, reduce endometriosis-associated pelvic pain? SUMMARY ANSWER: ASP1707 significantly reduced endometriosis-associated pelvic pain in a dose-related manner. WHAT IS KNOWN ALREADY: GnRH agonists are an effective therapeutic option for endometriosis that is refractory to non-steroidal anti-inflammatory drugs, oral contraceptives, and progestins. However, GnRH agonists cause complete suppression of estradiol (E2), resulting in hypoestrogenic side-effects such as bone loss that may increase the future risk of osteoporotic fractures. STUDY DESIGN, SIZE, DURATION: This was a Phase II, multicenter, double-blind, randomized, parallel-group, placebo-controlled study conducted in 540 women from 04 December 2012 to 30 July 2015 in Europe and Japan. A sample size of 504 (84 subjects per group) was calculated to provide ≥80% power to detect a dose-related treatment effect among placebo and ASP1707 doses in change from baseline in pelvic pain, assuming different dose-response curves after 12 weeks of treatment. PARTICIPANTS/MATERIALS, SETTING, METHODS: Of 912 women with endometriosis-associated pelvic pain screened, 540 were enrolled, and 532 received ≥1 dose of study drug (placebo, n = 88; ASP1707 3 mg, n = 86; ASP1707 5 mg, n = 91; ASP1707 10 mg, n = 90; ASP1707 15 mg, n = 88; leuprorelin, n = 89) for 24 weeks. MAIN RESULTS AND THE ROLE OF CHANCE: After 12 weeks of treatment with ASP1707, the mean (95% CI) changes in numeric rating score (NRS) for overall pelvic pain (OPP) were -1.56 (-1.91, -1.21), -1.63 (-1.99, -1.27), -1.93 (-2.27, -1.60), -2.29 (-2.64, -1.94), and -2.13 (-2.47, -1.79) for placebo, ASP1707 3 mg, ASP1707 5 mg, ASP1707 10 mg, and ASP1707 15 mg, respectively. Mean (95% CI) changes in NRS for dysmenorrhea were -1.50 (-2.00, -1.00), -2.72 (-3.22, -2.21), -2.85 (-3.33, -2.38), -3.97 (-4.46, -3.48), and -4.18 (-4.66, -3.70), respectively. Mean (95% CI) changes in NRS for non-menstrual pelvic pain (NMPP) were -1.53 (-1.88, -1.19), -1.51 (-1.87, -1.16), -1.80 (-2.14, -1.47), -2.03 (-2.37, -1.68), and -1.86 (-2.20, -1.52), respectively. Statistically significant dose-related treatment effects in reduction in NRS for OPP (P = 0.001), dysmenorrhea (P < 0.001), and NMPP (P = 0.029) were observed after 12 weeks among ASP1707 doses and were maintained through 24 weeks. Serum estradiol and bone mineral density decreased dose dependently with ASP1707 through 24 weeks, however, to a lesser extent than with leuprorelin. LIMITATIONS, REASON FOR CAUTION: This study was not powered for pairwise comparison of each ASP1707 group versus placebo. WIDER IMPLICATIONS OF THE FINDINGS: All doses of ASP1707 reduced serum E2 levels to within the target range and to a lesser extent than leuprorelin. ASP1707 is a potential alternative treatment to leuprorelin for endometriosis-associated pelvic pain with lower impact on bone health. STUDY FUNDING/COMPETING INTEREST(S): This study was funded by Astellas Pharma Inc. T.D'.H is Vice President and Head of Global Medical Affairs Fertility at Merck, Darmstadt, Germany since October 1, 2015. At the time that the TERRA study was conducted, he served as Principal Investigator in his role as Coordinator of the Leuven University Fertility Center. Since October 2015, T.D'.H has left Leuven University Hospital Gasthuisberg, but continues to serve as Professor in Reproductive Medicine and Biology at KU Leuven (University of Leuven) Belgium and at the Dept of Obstetrics, Gynecology and Reproduction at Yale University, New Haven, USA. T. Fukaya and Y. Osuga report personal consulting fees from Astellas Pharma Inc. during the conduct of the study and outside the submitted work. G.M. Holtkamp, and L. Skillern are employed by Astellas Pharma Europe B.V.; K. Miyazaki is employed by Astellas Pharma Inc.; B. López, was a biostatistician for Astellas Pharma Europe B.V. during conduct of the study; R. Besuyen was a contract Associate Director of Medical Science for Astellas during conduct of the study. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov, www.clinicaltrials.gov, NCT01767090. EudraCT number 2012-002791-14. TRIAL REGISTRATION DATE: 18 December 2012. DATE OF FIRST SUBJECT'S ENROLLMENT: One subject signed informed consent on 04 December 2012; the first subject was randomized on 16 April 2013.

Mitogen- and stress-activated protein kinase 1 is required for gonadotropin-releasing hormone-mediated activation of gonadotropin α-subunit expression.

Pituitary gonadotropin hormones are regulated by gonadotropin-releasing hormone (GnRH) via MAPK signaling pathways that stimulate gene transcription of the common α-subunit (Cga) and the hormone-specific ß-subunits of gonadotropin. We have reported previously that GnRH-induced activities at these genes include various histone modifications, but we did not examine histone phosphorylation. This modification adds a negative charge to residues of the histone tails that interact with the negatively charged DNA, is associated with closed chromatin during mitosis, but is increased at certain genes for transcriptional activation. Thus, the functions of this modification are unclear. We initially hypothesized that GnRH might induce phosphorylation of Ser-10 in histone 3 (H3S10p) as part of its regulation of gonadotropin gene expression, possibly involving cross-talk with H3K9 acetylation. We found that GnRH increases the levels of both modifications around the Cga gene transcriptional start site and that JNK inhibition dramatically reduces H3S10p levels. However, this modification had only a minor effect on Cga expression and no effect on H3K9ac. GnRH also increased H3S28p and H3K27ac levels and also those of activated mitogen- and stress-activated protein kinase 1 (MSK1). MSK1 inhibition dramatically reduced H3S28p levels in untreated and GnRH-treated cells and also affected H3K27ac levels. Although not affecting basal Cga expression, MSK1/2 inhibition repressed GnRH activation of Cga expression. Moreover, ChIP analysis revealed that GnRH-activated MSK1 targets the first nucleosome just downstream from the TSS. Given that the elongating RNA polymerase II (RNAPII) stalls at this well positioned nucleosome, GnRH-induced H3S28p, possibly in association with H3K27ac, would facilitate the progression of RNAPII.

Administration of leuprolide acetate, a GnRH agonist, improves urodynamic parameters in ovariectomized rats.

AIM: To evaluate the effects of a treatment with leuprolide acetate (LA) on bladder overactivity as well as the expression of gonadotropin releasing hormone receptor (GnRH-R), and neurofilaments NF68 and NF200 in female rats with overactive bladder induced by castration. METHODS: Changes in the urodynamic parameters were determined in SHAM, ovariectomized (OVX) and ovariectomized rats treated with LA (OVX-LA). A semi-quantitative analysis for the expression pattern of GnRH-R and neurofilaments NF68 and NF200 were determined. RESULTS: Forty-three days after ovariectomy, rats from the OVX group have significant lower values for intercontractile interval (ICI) and compliance (C); as well as higher values for basal bladder pressure (BP) and frequency of non-voiding contractions (NVC). The systemic application of LA increased voiding volume (Vv) and pressure threshold (ThP) in the OVX-LA animals. The application of LA reduced the high frequency of NVC in the OVX rats. No significant differences were found for Vv and NVCs between the OVX-LA vs SHAM groups. At the mid part of the bladder, the presence of GnRH-R was evidenced in the urothelium of the SHAM group. The OVX animals showed different pattern of immunolabeling for GnRH-R as well as for neurofilaments NF200 and NF68, whereas in the OVX-LA group the immunofluorescence pattern was similar to the one seen in SHAM bladders (P < 0.05 for OVX vs OVX + LA). CONCLUSIONS: the results suggest that systemic application of LA can improve bladder dysfunction in castrated rats, and perhaps considered as a treatment for overactive bladder conditions secondary to menopause.

Preventing ovarian failure associated with chemotherapy.

Alkylating chemotherapy is often used to treat pre-menopausal women for various malignancies and autoimmune diseases. Chemotherapy-associated ovarian failure is a potential consequence of this treatment which can cause infertility, and increases the risk of other long term adverse health sequelae. Randomised trials, predominantly of women undergoing alkylating chemotherapy for breast cancer, have shown evidence for the efficacy of gonadotropin-releasing hormone agonists (GnRHa) in preventing chemotherapy-associated ovarian failure. The European St Gallen and United States National Comprehensive Cancer Network guidelines recommend the use of concurrent GnRHa to reduce the risk of ovarian failure for pre-menopausal women undergoing chemotherapy for breast cancer. The GnRHa goserelin, a monthly 3.6 mg depot subcutaneous injection, has recently been listed on the Australian Pharmaceutical Benefits Scheme to reduce risk of ovarian failure for pre-menopausal women receiving alkylating therapies for malignancy or autoimmune disease. The first dose of goserelin should ideally be administered at least 1 week before commencement of alkylating treatment and continued 4-weekly during chemotherapy. Concurrent goserelin use should now be considered for all pre-menopausal women due to commence alkylating chemotherapy (except those with incurable cancer), regardless of their childbearing status, in an effort to preserve their ovarian function. For women who have not completed childbearing, consideration of other fertility preservation options, such as cryopreservation of embryos or oocytes, is also important.

A biomimetic approach for enhancing the in vivo half-life of peptides.

The tremendous therapeutic potential of peptides has not yet been realized, mainly owing to their short in vivo half-life. Although conjugation to macromolecules has been a mainstay approach for enhancing protein half-life, the steric hindrance of macromolecules often harms the binding of peptides to target receptors, compromising the in vivo efficacy. Here we report a new strategy for enhancing the in vivo half-life of peptides without compromising their potency. Our approach involves endowing peptides with a small molecule that binds reversibly to the serum protein transthyretin. Although there are a few molecules that bind albumin reversibly, we are unaware of designed small molecules that reversibly bind other serum proteins and are used for half-life extension in vivo. We show here that our strategy was effective in enhancing the half-life of an agonist for GnRH receptor while maintaining its binding affinity, which was translated into superior in vivo efficacy.

Non-steroidal antiandrogen monotherapy compared with luteinizing hormone-releasing hormone agonists or surgical castration monotherapy for advanced prostate cancer: a Cochrane systematic review.

To assess the effects of non-steroidal antiandrogen monotherapy compared with luteinizing hormone-releasing hormone agonists or surgical castration monotherapy for treating advanced hormone-sensitive stages of prostate cancer. We searched the Cochrane Prostatic Diseases and Urologic Cancers Group Specialized Register (PROSTATE), the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Web of Science with Conference Proceedings, three trial registries and abstracts from three major conferences to 23 December 2013, together with reference lists, and contacted selected experts in the field and manufacturers. We included randomized controlled trials comparing non-steroidal antiandrogen monotherapy with medical or surgical castration monotherapy for men in advanced hormone-sensitive stages of prostate cancer. Two review authors independently examined full-text reports, identified relevant studies, assessed the eligibility of studies for inclusion, extracted data and assessed risk of bias as well as quality of evidence according to the GRADE working group guidelines. We used Review Manager 5.2 for data synthesis and the fixed-effect model as primary analysis (when heterogeneity was low with I(2) < 50%); we used a random-effects model when confronted with substantial or considerable heterogeneity (when I(2) ≥50%). A total of 11 studies involving 3060 randomly assigned participants were included in the present review. Use of non-steroidal antiandrogens resulted in lower overall survival times (hazard ratio [HR] 1.24, 95% confidence interval [CI] 1.05-1.48, six studies, 2712 participants) and greater clinical progression (1 year: risk ratio [RR] 1.25, 95% CI 1.08-1.45, five studies, 2067 participants; 70 weeks: RR 1.26, 95% CI 1.08-1.45, six studies, 2373 participants; 2 years: RR 1.14, 95% CI 1.04-1.25, three studies, 1336 participants), as well as treatment failure (1 year: RR 1.19, 95% CI 1.02-1.38, four studies, 1539 participants; 70 weeks: RR 1.27, 95% CI 1.05-1.52, five studies, 1845 participants; 2 years: RR 1.14, 95% CI 1.05-1.24, two studies, 808 participants), compared with medical or surgical castration. The quality of evidence for overall survival, clinical progression and treatment failure was rated as moderate according to GRADE. Use of non-steroidal antiandrogens increased the risk for treatment discontinuation as a result of adverse events (RR 1.82, 95% CI 1.13-2.94, eight studies, 1559 participants), including events such as breast pain (RR 22.97, 95% CI 14.79- 35.67, eight studies, 2670 participants) and gynaecomastia (RR 8.43, 95% CI 3.19-22.28, nine studies, 2774 participants) The risk of other adverse events, such as hot flushes (RR 0.23, 95% CI 0.19-0.27, nine studies, 2774 participants) was decreased when non-steroidal antiandrogens were used. The quality of evidence for breast pain, gynaecomastia and hot flushes was rated as moderate according to GRADE. The effects of non-steroidal antiandrogens on cancer-specific survival and biochemical progression remained unclear. Non-steroidal antiandrogen monotherapy compared with medical or surgical castration monotherapy for advanced prostate cancer is less effective in terms of overall survival, clinical progression, treatment failure and treatment discontinuation resulting from adverse events. Evidence quality was rated as moderate according to GRADE; therefore, further research is likely to have an important impact on results for patients with advanced but non-metastatic prostate cancer treated with non-steroidal antiandrogen monotherapy.

Phase II, randomised, double-blind, placebo-controlled trial of methylphenidate for reduction of fatigue levels in patients with prostate cancer receiving LHRH-agonist therapy.

OBJECTIVES: To investigate whether methylphenidate can alleviate fatigue, as measured by the Functional Assessment of Cancer Therapy: Fatigue subscale, in men with prostate cancer (PCa) treated with a luteinizing hormone-releasing hormone (LHRH) for a minimum of 6 months, and to assess changes in global fatigue and quality of life (QoL) as measured by the Bruera Global Fatigue Severity Scale (BFS) and the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), respectively. PARTICIPANTS AND METHODS: We performed a single-centre, randomised, double-blind, placebo-controlled trial with the aim of recruiting 128 participants. Men treated with a LHRH agonist for PCa were screened between February 2008 and June 2012 for fatigue at our outpatient clinics using the BFS. Participants were randomised to receive either 10 mg daily of methylphenidate or placebo. Change in fatigue levels and in SF-36 scores between both groups were compared using linear regression, adjusted for baseline scores. RESULTS: The study was closed prematurely because of poor accrual. Of the 790 subjects screened, 24 men were randomised to methylphenidate or placebo (12 per group). After 10 weeks, the improvement in mean [sd] fatigue score was greater in the methylphenidate than in the placebo arm (+7.7 [7.7] vs +1.4 [7.6]; P = 0.022). The within-group analysis showed a significant improvement in fatigue scores in the methylphenidate arm (P = 0.008) but not in the placebo arm (P = 0.82). The use of methylphenidate also resulted in a significantly greater improvement in QoL as measured by the physical and mental component summary scores than did the use of placebo (P = 0.04 for both component scores). CONCLUSIONS: Our findings support the beneficial effect of methylphenidate on fatigue and QoL among men with LHRH-induced fatigue. Clinicians should be aware of these benefits and should consider discussing these findings with patients who have high levels of fatigue.

Cardiovascular outcomes in patients with locally advanced and metastatic prostate cancer treated with luteinising-hormone-releasing-hormone agonists or transdermal oestrogen: the randomised, phase 2 MRC PATCH trial (PR09).

BACKGROUND: Luteinising-hormone-releasing-hormone agonists (LHRHa) to treat prostate cancer are associated with long-term toxic effects, including osteoporosis. Use of parenteral oestrogen could avoid the long-term complications associated with LHRHa and the thromboembolic complications associated with oral oestrogen. METHODS: In this multicentre, open-label, randomised, phase 2 trial, we enrolled men with locally advanced or metastatic prostate cancer scheduled to start indefinite hormone therapy. Randomisation was by minimisation, in a 2:1 ratio, to four self-administered oestrogen patches (100 µg per 24 h) changed twice weekly or LHRHa given according to local practice. After castrate testosterone concentrations were reached (1·7 nmol/L or lower) men received three oestrogen patches changed twice weekly. The primary outcome, cardiovascular morbidity and mortality, was analysed by modified intention to treat and by therapy at the time of the event to account for treatment crossover in cases of disease progression. This study is registered with ClinicalTrials.gov, number NCT00303784. FINDINGS: 85 patients were randomly assigned to receive LHRHa and 169 to receive oestrogen patches. All 85 patients started LHRHa, and 168 started oestrogen patches. At 3 months, 70 (93%) of 75 receiving LHRHa and 111 (92%) of 121 receiving oestrogen had achieved castrate testosterone concentrations. After a median follow-up of 19 months (IQR 12-31), 24 cardiovascular events were reported, six events in six (7·1%) men in the LHRHa group (95% CI 2·7-14·9) and 18 events in 17 (10·1%) men in the oestrogen-patch group (6·0-15·6). Nine (50%) of 18 events in the oestrogen group occurred after crossover to LHRHa. Mean 12-month changes in fasting glucose concentrations were 0·33 mmol/L (5·5%) in the LHRHa group and -0·16 mmol/L (-2·4%) in the oestrogen-patch group (p=0·004), and for fasting cholesterol were 0·20 mmol/L (4·1%) and -0·23 mmol/L (-3·3%), respectively (p<0·0001). Other adverse events reported by 6 months included gynaecomastia (15 [19%] of 78 patients in the LHRHa group vs 104 [75%] of 138 in the oestrogen-patch group), hot flushes (44 [56%] vs 35 [25%]), and dermatological problems (10 [13%] vs 58 [42%]). INTERPRETATION: Parenteral oestrogen could be a potential alternative to LHRHa in management of prostate cancer if efficacy is confirmed. On the basis of our findings, enrolment in the PATCH trial has been extended, with a primary outcome of progression-free survival. FUNDING: Cancer Research UK, MRC Clinical Trials Unit.

Luteinizing hormone-releasing hormone (LHRH) receptor agonists vs antagonists: a matter of the receptors?

Luteinizing hormone-releasing hormone (LHRH) agonists and antagonists are commonly used androgen deprivation therapies prescribed for patients with advanced prostate cancer (PCa). Both types of agent target the receptor for LHRH but differ in their mode of action: agonists, via pituitary LRHR receptors (LHRH-Rs), cause an initial surge in luteinizing hormone (LH), follicle-stimulating hormone (FSH) and, subsequently, testosterone. Continued overstimulation of LHRH-R down-regulates the production of LH and leads to castrate levels of testosterone. LHRH antagonists, however, block LHRH-R signalling causing a rapid and sustained inhibition of testosterone, LH and FSH. The discovery and validation of the presence of functional LHRH-R in the prostate has led to much work investigating the role of LHRH signalling in the normal prostate as well as in the treatment of PCa with LHRH agonists and antagonists. In this review we discuss the expression and function of LHRH-R, as well as LH/human chorionic gonadotropin receptors and FSH receptors and relate this to the differential clinical responses to agonists and antagonists used in the hormonal manipulation of PCa.

The forkhead transcription factor, FOXP3, is required for normal pituitary gonadotropin expression in mice.

The hypothalamic-pituitary-gonadal axis is central to normal reproductive function. This pathway begins with the release of gonadotropin-releasing hormone in systematic pulses by the hypothalamus. Gonadotropin-releasing hormone is bound by receptors on gonadotroph cells in the anterior pituitary gland and stimulates the synthesis and secretion of luteinizing hormone and, to some extent, follicle-stimulating hormone. Once stimulated by these glycoprotein hormones, the gonads begin gametogenesis and the synthesis of sex hormones. In humans, mutations of the forkhead transcription factor, FOXP3, lead to an autoimmune disorder known as immunodysregulation, polyendocrinopathy, and enteropathy, X-linked syndrome. Mice with a mutation in the Foxp3 gene have a similar autoimmune syndrome and are infertile. To understand why FOXP3 is required for reproductive function, we are investigating the reproductive phenotype of Foxp3 mutant mice (Foxp3(sf/Y)). Although the gonadotroph cells appear to be intact in Foxp3(sf/Y) mice, luteinizing hormone beta (Lhb) and follicle-stimulating hormone beta (Fshb) expression are significantly decreased, demonstrating that these mice exhibit a hypogonadotropic hypogonadism. Hypothalamic expression of gonadotropin-releasing hormone is not significantly decreased in Foxp3(sf/Y) males. Treatment of Foxp3(sf/Y) males with a gonadotropin-releasing hormone receptor agonist does not rescue expression of Lhb or Fshb. Interestingly, we do not detect Foxp3 expression in the pituitary or hypothalamus, suggesting that the infertility seen in Foxp3(sf/Y) males is a secondary effect, possibly due to loss of FOXP3 in immune cells. Pituitary expression of glycoprotein hormone alpha (Cga) and prolactin (Prl) are significantly reduced in Foxp3(sf/Y) males, whereas the precursor for adrenocorticotropic hormone, pro-opiomelanocortin (Pomc), is increased. Human patients diagnosed with IPEX often exhibit thyroiditis due to destruction of the thyroid gland by autoimmune cells. We find that Foxp3(sf/Y) mice have elevated expression of thyroid-stimulating hormone beta (Tshb), suggesting that they may suffer from thyroiditis as well. Expression of the pituitary transcription factors, Pitx1, Pitx2, Lhx3, and Egr1, is normal; however, expression of Foxl2 and Gata2 is elevated. These data are the first to demonstrate a defect at the pituitary level in the absence of FOXP3, which contributes to the infertility observed in mice with Foxp3 loss of function mutations.

Gonadotropin-releasing hormone receptor activates GTPase RhoA and inhibits cell invasion in the breast cancer cell line MDA-MB-231.

BACKGROUND: Gonadotropin-releasing hormone (GnRH) and its receptor (GnRHR) are both expressed by a number of malignant tumors, including those of the breast. In the latter, both behave as potent inhibitors of invasion. Nevertheless, the signaling pathways whereby the activated GnRH/GnRHR system exerts this effect have not been clearly established. In this study, we provide experimental evidence that describes components of the mechanism(s) whereby GnRH inhibits breast cancer cell invasion. METHODS: Actin polymerization and substrate adhesion was measured in the highly invasive cell line, MDA-MB-231 transiently expressing the wild-type or mutant DesK191 GnRHR by fluorometry, flow cytometric analysis, and confocal microscopy, in the absence or presence of GnRH agonist. The effect of RhoA-GTP on stress fiber formation and focal adhesion assembly was measured in MDA-MB-231 cells co-expressing the GnRHRs and the GAP domain of human p190Rho GAP-A or the dominant negative mutant GAP-Y1284D. Cell invasion was determined by the transwell migration assay. RESULTS: Agonist-stimulated activation of the wild-type GnRHR and the highly plasma membrane expressed mutant GnRHR-DesK191 transiently transfected to MDA-MB-231 cells, favored F-actin polymerization and substrate adhesion. Confocal imaging allowed detection of an association between F-actin levels and the increase in stress fibers promoted by exposure to GnRH. Pull-down assays showed that the effects observed on actin cytoskeleton resulted from GnRH-stimulated activation of RhoA GTPase. Activation of this small G protein favored the marked increase in both cell adhesion to Collagen-I and number of focal adhesion complexes leading to inhibition of the invasion capacity of MDA-MB-231 cells as disclosed by assays in Transwell Chambers. CONCLUSIONS: We here show that GnRH inhibits invasion of highly invasive breast cancer-derived MDA-MB-231 cells. This effect is mediated through an increase in substrate adhesion promoted by activation of RhoA GTPase and formation of stress fibers and focal adhesions. These observations offer new insights into the molecular mechanisms whereby activation of overexpressed GnRHRs affects cell invasion potential of this malignant cell line, and provide opportunities for designing mechanism-based adjuvant therapies for breast cancer.

Pharmacoperone IN3 enhances the apoptotic effect of leuprolide in prostate cancer cells by increasing the gonadotropin-releasing hormone receptor in the cell membrane.

Gonadotropin-releasing hormone (GnRH) agonists are widely used for the treatment of advanced prostate cancer (PCa). Agonists activate the GnRH receptor (GnRH-R), triggering apoptosis in PCa cells. In gonadotropes, the amount of GnRH-R in the plasma membrane is regulated by protein folding and endoplasmic reticulum retention, mechanisms that can be overcome by the pharmacoperone IN3. Our aim was to describe the intracellular distribution of GnRH-R in PCa cells and its relation to response to GnRH analog treatments. The expressions of GnRH-R in PCa biopsies were evaluated by immunohistochemistry and the intracellular distribution was determined by immunofluorescence in primary cell cultures from human PCa samples. Cultured cells were pretreated with IN3 and then with leuprolide. Cell survival was evaluated by 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan (MTT) thiazolyl blue formazan and cell cycle and apoptosis by flow cytometry. We observed that the expression of GnRH-R decreased according to malignant progression. Most GnRH-R are located inside the cell, colocalizing with endoplasmic reticulum markers. The treatment with IN3 decreased cellular GnRH-R retention, increasing plasma membrane expression in approximately 60%. Pretreatment with IN3 decreased PCa cell survival compared with leuprolide-alone treatment, primarily because of an increase in apoptosis. We conclude that the response of PCa cells to leuprolide is related to the amount of GnRH-R in the plasma membrane. Therefore, pretreatment evaluation of the amount of these receptors may be a predictor of the outcome of leuprolide treatment in PCa patients. Assessment of systemic IN3 effect would be necessary to determine its utility as an adjuvant treatment in hormone-resistant tumors.

Agonists and antagonists of GnRH-I and -II reduce metastasis formation by triple-negative human breast cancer cells in vivo.

Metastasis to bone is a frequent problem of advanced breast cancer. Particularly breast cancers, which do not express estrogen and progesterone receptors and which have no overexpression/amplification of the HER2-neu gene, so called triple-negative breast cancers, are considered as very aggressive and possess a bad prognosis. About 60% of all human breast cancers and about 74% of triple-negative breast cancers express receptors for gonadotropin-releasing hormone (GnRH), which might be used as a therapeutic target. Recently, we could show that bone-directed invasion of human breast cancer cells in vitro is time- and dose-dependently reduced by GnRH analogs. In the present study, we have analyzed whether GnRH analogs are able to reduce metastases of triple-negative breast cancers in vivo. In addition, we have evaluated the effects of GnRH analogs on tumor growth. To quantify formation of metastasis by triple-negative MDA-MB-435 and MDA-MB-231 human breast cancers, we used a real-time PCR method based on detection of human-specific alu sequences measuring accurately the amount of human tumor DNA in athymic mouse organs. To analyze tumor growth, the volumes of breast cancer xenotransplants into nude mice were measured. We could demonstrate that GnRH analogs significantly reduced metastasis formation by triple-negative breast cancer in vivo. In addition, we could show that GnRH analogs significantly inhibited the growth of breast cancer into nude mice. Side effects were not detectable. In conclusion, GnRH analogs seem to be suitable drugs for an efficacious therapy for triple-negative, GnRH receptor-positive human breast cancers to prevent metastasis formation.

Development of programmable gemcitabine-GnRH pro-drugs bearing linker controllable "click" oxime bond tethers and preclinical evaluation against prostate cancer.

Peptide-drug conjugates (PDCs) are gaining considerable attention as anti-neoplastic agents. However, their development is often laborious and time-consuming. Herein, we have developed and preclinically evaluated three PDCs with gemcitabine as the anticancer cytotoxic unit and D-Lys6-GnRH (gonadotropin-releasing hormone; GnRH) as the cancer-targeting unit. These units were tethered via acid-labile programmable linkers to guide a differential drug release rate from the PDC through a combination of ester or amide and "click" type oxime ligations. The pro-drugs were designed to enable the selective targeting of malignant tumor cells with linker guided differential drug release rates. We exploited the oxime bond responsiveness against the acidic pH of the tumor microenvironment and the GnRH endocytosis via the GnRH-R GPCR which is overexpressed on cancer cells. The challenging metabolic properties of gemcitabine were addressed during design of the PDCs. We developed a rapid (1 hour) and cost-effective "click" oxime bond ligation platform to assemble in one-pot the 3 desired PDCs that does not require purification, surpassing traditional time-ineffective and low yield methods. The internalization of the tumor-homing peptide unit in cancer cells, overexpressing the GnRH-R, was first validated through confocal laser microscopy and flow cytometry analysis. Subsequently, the three PDCs were evaluated for their in vitro antiproliferative effect in prostate cancer cells. Their stability and the release of gemcitabine over time were monitored in vitro in cell culture and in human plasma using LC-MS/MS. We then assessed the ability of the developed PDCs to internalize in prostate cancer cells and to release gemcitabine. The most potent analog, designated GOXG1, was used for pharmacokinetic studies in mice. The metabolism of GOXG1 was examined in liver microsomes, as well as in buffers mimicking the pH of intracellular organelles, resulting in the identification of two metabolites. The major metabolite at low pH emanated from the cleavage of the pH-labile oxime bond, validating our design approach. NMR spectroscopy and in vitro radioligand binding assays were exploited for GOXG1 to validate that upon conjugating the drug to the peptide, the peptide microenvironment responsible for its GnRH-R binding is not perturbed and to confirm its high binding potency to the GnRH-R. Finally, the binding of GOXG1 to the GnRH-R and the associated elicitation of testosterone release in mice were also determined. The facile platform established herein for the rapid assembly of PDCs with linker controllable characteristics from aldehyde and aminooxy units through rapid "click" oxime ligation, that does not require purification steps, could pave the way for a new generation of potent cancer therapeutics, diagnostics and theranostics.

Rescue of mutant gonadotropin-releasing hormone receptor function independent of cognate receptor activity.

Molecules that correct the folding of protein mutants, restoring their functional trafficking, are called pharmacoperones. Most are clinically irrelevant and possess intrinsic antagonist or agonist activity. Here, we identify compounds capable of rescuing the activity of mutant gonadotropin-releasing hormone receptor or GnRHR which, is sequestered within the cell and if dysfunctional leads to Hypogonadotropic Hypogonadism. To do this we screened the E90K GnRHR mutant vs. a library of 645,000 compounds using a cell-based calcium detection system. Ultimately, we identified 399 compounds with EC50 ≤ 5 µM with no effect in counterscreen assays. Medicinal chemistry efforts confirmed activity of 70 pure samples and mode of action studies, including radioligand binding, inositol phosphate, and toxicity assays, proved that we have a series of tractable compounds that can be categorized into structural clusters. These early lead molecules rescue mutant GnRHR function and are neither agonist nor antagonists of the GnRHR cognate receptor, a feature required for potential clinical utility.

Cardiovascular risks and toxicity - The Achilles heel of androgen deprivation therapy in prostate cancer patients.

Androgen deprivation therapy (ADT) is the primary systemic therapy for treating locally advanced or metastatic prostate cancer (PCa). Despite its positive effect on PCa patient survival, ADT causes various adverse effects, including increased cardiovascular risk factors and cardiotoxicity. Lifespans extension, early use of ADT, and second-line treatment with next-generation androgen receptor pathway inhibitors would further extend the duration of ADT and possibly increase the risk of ADT-induced cardiotoxicity. Meanwhile, information on the molecular mechanisms underlying ADT-induced cardiotoxicity and measures to prevent it is limited, mainly due to the lack of specifically designed preclinical studies and clinical trials. This review article compiles up-to-date evidence obtained from observational studies and clinical trials, in order to gain new insights for deciphering the association between ADT use and cardiotoxicity. In addition, potential cardioprotective strategies involving GnRH receptors and second messenger cGMP are discussed.

Diversity of actions of GnRHs mediated by ligand-induced selective signaling.

Geoffrey Wingfield Harris' demonstration of hypothalamic hormones regulating pituitary function led to their structural identification and therapeutic utilization in a wide spectrum of diseases. Amongst these, Gonadotropin Releasing Hormone (GnRH) and its analogs are widely employed in modulating gonadotropin and sex steroid secretion to treat infertility, precocious puberty and many hormone-dependent diseases including endometriosis, uterine fibroids and prostatic cancer. While these effects are all mediated via modulation of the pituitary gonadotrope GnRH receptor and the G(q) signaling pathway, it has become increasingly apparent that GnRH regulates many extrapituitary cells in the nervous system and periphery. This review focuses on two such examples, namely GnRH analog effects on reproductive behaviors and GnRH analog effects on the inhibition of cancer cell growth. For both effects the relative activities of a range of GnRH analogs is distinctly different from their effects on the pituitary gonadotrope and different signaling pathways are utilized. As there is only a single functional GnRH receptor type in man we have proposed that the GnRH receptor can assume different conformations which have different selectivity for GnRH analogs and intracellular signaling proteins complexes. This ligand-induced selective-signaling recruits certain pathways while by-passing others and has implications in developing more selective GnRH analogs for highly specific therapeutic intervention.