Publications by authors named "Michael D Culler"

78 Publications

The cryptic gonadotropin-releasing hormone neuronal system of human basal ganglia.

Elife 2021 Jun 15;10. Epub 2021 Jun 15.

Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Budapest, Hungary.

Human reproduction is controlled by ~2000 hypothalamic gonadotropin-releasing hormone (GnRH) neurons. Here, we report the discovery and characterization of additional ~150,000-200,000 GnRH-synthesizing cells in the human basal ganglia and basal forebrain. Nearly all extrahypothalamic GnRH neurons expressed the cholinergic marker enzyme choline acetyltransferase. Similarly, hypothalamic GnRH neurons were also cholinergic both in embryonic and adult human brains. Whole-transcriptome analysis of cholinergic interneurons and medium spiny projection neurons laser-microdissected from the human putamen showed selective expression of and autoreceptors in the cholinergic cell population and uncovered the detailed transcriptome profile and molecular connectome of these two cell types. Higher-order non-reproductive functions regulated by GnRH under physiological conditions in the human basal ganglia and basal forebrain require clarification. The role and changes of GnRH/GnRHR1 signaling in neurodegenerative disorders affecting cholinergic neurocircuitries, including Parkinson's and Alzheimer's diseases, need to be explored.
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http://dx.doi.org/10.7554/eLife.67714DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8245125PMC
June 2021

Characterization of the ability of a, second-generation SST-DA chimeric molecule, TBR-065, to suppress GH secretion from human GH-secreting adenoma cells.

Pituitary 2021 Jun 12;24(3):351-358. Epub 2021 Jan 12.

Laboratoire de Biologie Moléculaire et Biochimie, Aix Marseille University, APHM, Marseille Medical Genetics, Inserm U1251, Hôpital de la Conception, Marseille, France.

Context: Somatostatin (SST) and dopamine (DA) inhibit growth hormone (GH) secretion and proliferation of GH-secreting pituitary adenomas (GHomas) through binding to SSTR2 and D2R receptors. Chimeric SST-DA compounds (Dopastatins) display increased potency in inhibiting GH secretion, as compared with individual SST or DA analogs (alone or combined).

Objective: To assess the efficacy of a second-generation dopastatin, TBR-065, in suppressing GH secretion from human GH- and GH/prolactin(PRL)-omas.

Design: We compared the ability of TBR-065 to inhibit GH secretion from primary cultures of human GH- or GH/PRLoma cells to that of the first generation dopastatin, TBR-760 (formerly BIM-23A760), octreotide (OCT) and cabergoline (CAB), the later either alone or combined. We investigated whether there was any impact of BIM-133, the metabolite of TBR-065, on the ability of TBR-065 to inhibit GH in these cultures.

Methods: 17 GH- and GH/PRLomas were included in this study. Inhibition of GH secretion by TBR-065, TBR-760, OCT and CAB (0.1 pM to 0.1 µM) was assessed over a period of 8 h.

Results: All tumors expressed SSTR2 and D2R mRNAs. GH suppression was higher with TBR-065 as compared with TBR-760 (E = 57 ± 5.6% vs. 41.1 ± 12.5%, respectively, p < 0.001) or with OCT + CAB (E = 56.8 ± 7.2% vs. 44.4 ± 9.4%, p < 0.001). BIM-133 did not have any impact on the activity of TBR-065.

Conclusion: TBR-065 has significantly improved efficacy in suppressing GH secretion as compared to current available therapies and may represent a new promising option for the treatment of acromegaly.
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http://dx.doi.org/10.1007/s11102-020-01113-4DOI Listing
June 2021

TBR-760, a Dopamine-Somatostatin Compound, Arrests Growth of Aggressive Nonfunctioning Pituitary Adenomas in Mice.

Endocrinology 2020 08;161(8)

Tiburio Therapeutics, Cambridge, Massachusetts.

TBR-760 (formerly BIM-23A760) is a chimeric dopamine (DA)-somatostatin (SST) compound with potent agonist activity at both DA type 2 (D2R) and SST type 2 (SSTR2) receptors. Studies have shown that chimeric DA-SST compounds are more efficacious than individual DA and/or SST analogues, either alone or combined, in inhibiting secretion from primary cultures of human somatotroph and lactotroph tumor cells. Nonfunctioning pituitary adenomas (NFPAs) express both D2R and SSTR2 and, consequently, may respond to TBR-760. We used a mouse model with the pro-opiomelanocortin (POMC) gene knocked out that spontaneously develops aggressive NFPAs. Genomic microarray and DA and SST receptor messenger RNA expression analysis indicate that POMC KO mouse tumors and human NFPAs have similar expression profiles, despite arising from different cell lineages, establishing POMC KO mice as a model for study of NFPAs. Treatment with TBR-760 for 8 weeks resulted in nearly complete inhibition of established tumor growth, whereas tumors from vehicle-treated mice increased in size by 890 ± 0.7%. Comparing TBR-760 with its individual DA and SST components, TBR-760 arrested tumor growth. Treatment with equimolar or 10×-higher doses of the individual SST or DA agonists, either alone or in combination, had no significant effect. One exception was the lower dose of DA agonist that induced modest suppression of tumor growth. Only the chimeric compound TBR-760 arrested tumor growth in this mouse model of NFPA. Further, significant tumor shrinkage was observed in 20% of the mice treated with TBR-760. These results support the development of TBR-760 as a therapy for patients with NFPA.
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http://dx.doi.org/10.1210/endocr/bqaa101DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7375803PMC
August 2020

Therapeutic Effect of a Novel Chimeric Molecule Targeting Both Somatostatin and Dopamine Receptors on Growth Hormone-Secreting Pituitary Adenomas.

Endocrinol Metab (Seoul) 2020 03;35(1):177-187

Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul, Korea.

Background: Acromegaly is a rare disease primarily caused by growth hormone (GH)-secreting pituitary adenomas, and its treatment is costly. Moreover, some patients are unresponsive to treatment. Hence, there are increasing efforts to develop new drugs with improved effectiveness for this disease. BIM23B065 is a novel chimeric molecule that acts on both somatostatin and dopamine receptors. This study aimed to investigate the effects of BIM23B065 compared with those of a somatostatin receptor analog and a dopamine agonist.

Methods: The effects of BIM23B065 on the proliferation, GH and insulin-like growth factor-1 (IGF-1) levels, and extracellular signal-regulated kinase (ERK) 1/2 and cyclic AMP response element binding (CREB) phosphorylation of GH3 cells were investigated with MTS assay, enzyme-linked immunosorbent assay, and Western blotting, respectively. The dosage and treatment duration of BIM23B065 were tested in animal models of GH-secreting pituitary adenoma. The effect of BIM23B065 (3 mg/kg/day) on changes in IGF-1 levels before and after treatment was further investigated.

Results: , BIM23B065 treatment decreased GH release in the culture media and downregulated ERK 1/2 and CREB phosphorylation to 22% and 26%, respectively. , IGF-1 expression decreased to 50 % after 4 weeks of treatment with BIM23B065 using an osmotic pump implant. Moreover, magnetic resonance imaging results showed that the tumor size decreased significantly following treatment with BIM23B065 for 4 weeks.

Conclusion: The novel chimeric molecule was effective in decreasing IGF-1 and GH levels and may serve as an effective therapeutic agent for acromegaly.
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http://dx.doi.org/10.3803/EnM.2020.35.1.177DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7090307PMC
March 2020

A Somatostatin Receptor Subtype-3 (SST) Peptide Agonist Shows Antitumor Effects in Experimental Models of Nonfunctioning Pituitary Tumors.

Clin Cancer Res 2020 02 17;26(4):957-969. Epub 2019 Oct 17.

Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain.

Purpose: Somatostatin analogues (SSA) are efficacious and safe treatments for a variety of neuroendocrine tumors, especially pituitary neuroendocrine tumors (PitNET). Their therapeutic effects are mainly mediated by somatostatin receptors SST and SST. Most SSAs, such as octreotide/lanreotide/pasireotide, are either nonselective or activate mainly SST. However, nonfunctioning pituitary tumors (NFPTs), the most common PitNET type, mainly express SST and finding peptides that activate this particular somatostatin receptor has been very challenging. Therefore, the main objective of this study was to identify SST-agonists and characterize their effects on experimental NFPT models.

Experimental Design: Binding to SSTs and cAMP level determinations were used to screen a peptide library and identify SST-agonists. Key functional parameters (cell viability/caspase activity/chromogranin-A secretion/mRNA expression/intracellular signaling pathways) were assessed on NFPT primary cell cultures in response to SST-agonists. Tumor growth was assessed in a preclinical PitNET mouse model treated with a SST-agonist.

Results: We successfully identified the first SST-agonist peptides. SST-agonists lowered cell viability and chromogranin-A secretion, increased apoptosis , and reduced tumor growth in a preclinical PitNET model. As expected, inhibition of cell viability in response to SST-agonists defined two NFPT populations: responsive and unresponsive, wherein responsive NFPTs expressed more SST than unresponsive NFPTs and exhibited a profound reduction of MAPK, PI3K-AKT/mTOR, and JAK/STAT signaling pathways upon SST-agonist treatments. Concurrently, silencing increased cell viability in a subset of NFPTs.

Conclusions: This study demonstrates that SST-agonists activate signaling mechanisms that reduce NFPT cell viability and inhibit pituitary tumor growth in experimental models that expresses SST, suggesting that targeting this receptor could be an efficacious treatment for NFPTs.
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http://dx.doi.org/10.1158/1078-0432.CCR-19-2154DOI Listing
February 2020

A New Generation Somatostatin-Dopamine Analogue Exerts Potent Antitumoral Actions on Pituitary Neuroendocrine Tumor Cells.

Neuroendocrinology 2020 5;110(1-2):70-82. Epub 2019 Jul 5.

Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain,

Background: Pituitary neuroendocrine tumors (PitNETs) represent approximately 15% of all intracranial tumors and usually are associated with severe comorbidities. Unfortunately, a relevant number of patients do not respond to currently available pharmacological treatments, that is, somatostatin analogs (SSAs) or dopamine-agonists (DA). Thus, novel, chimeric somatostatin/dopamine compounds (dopastatins) that could improve medical treatment of PitNETs have been designed.

Objective: This study aims to determine the direct therapeutic effects of a new-generation dopastatin, BIM-065, on primary cell cultures from different PitNETs subtypes.

Methods: Thirty-one PitNET-derived cell cultures (9 corticotropinomas, 9 somatotropinomas, 11 nonfunctioning pituitary adenomas [NFPAs], and 2 prolactinomas), were treated with BIM-065, and key functional endpoints were assessed (cell viability, apoptosis, hormone secretion, expression levels of key genes, free cytosolic [Ca2+]i dynamics, etc.). AtT-20 cell line was used to evaluate signaling pathways in response to BIM-065.

Results: This chimeric compound decreased cell viability in all corticotropinomas and somatotropinomas tested, but not in NFPAs. BIM-065 reduced ACTH, GH, chromogranin-A and PRL secretion, and increased apoptosis in corticotropinomas, somatotropinomas, and NFPAs. These effects were possibly mediated through modulation of pivotal signaling cascades like [Ca2+]i kinetic and Akt- or ERK1/2-phosphorylation.

Conclusions: Our results unveil a robust antitumoral effect in vitro of the novel chimeric compound BIM-065 on the main PitNET subtypes, inform on the mechanisms involved, and suggest that BIM-065 could be an efficacious therapeutic option to be considered in the treatment of PitNETs.
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http://dx.doi.org/10.1159/000500812DOI Listing
February 2021

Effects of novel somatostatin-dopamine chimeric drugs in 2D and 3D cell culture models of neuroendocrine tumors.

Endocr Relat Cancer 2019 06;26(6):585-599

Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, Rotterdam, the Netherlands.

Control of symptoms related to hormonal hypersecretion by functioning neuroendocrine tumors (NETs) is challenging. New therapeutic options are required. Since novel in vitro tumor models seem to better mimic the tumor in vivo conditions, we aimed to study the effect of somatostatin and dopamine receptor agonists (octreotide and cabergoline, respectively) and novel somatostatin-dopamine chimeric multi-receptor drugs (BIM-065, BIM-23A760) using 2D (monolayer) and 3D (spheroids) cultures. Dose-response studies in 2D and 3D human pancreatic NET cell cultures (BON-1 and QGP-1) were performed under serum-containing and serum-deprived conditions. Cell proliferation, somatostatin and dopamine receptor expression (SSTs and D2R), apoptosis, lactate dehydrogenase, as well as serotonin and chromogranin A (CgA) release were assessed. The following results were obtained. 3D cultures of BON-1/QGP-1 allowed better cell survival than 2D cultures in serum-deprived conditions. SSTs and D2R mRNA levels were higher in the 3D model vs 2D model. Octreotide/cabergoline/BIM-065/BIM-23A760 treatment did not affect cell growth or spheroid size. In BON-1 2D-cultures, only BIM-23A760 significantly inhibited CgA release -this effect being more pronounced in 3D cultures. In BON-1 2D cultures, cabergoline/BIM-065/BIM-23A760 treatment decreased serotonin release (maximal effect up to 40%), being this effect again more potent in 3D cultures (up to 67% inhibition; with BIM-23A760 having the most potent effects). In QGP-1, cabergoline/BIM-065 treatment decreased serotonin release only in the 3D model. In conclusion, cultures of NET 3D spheroids represent a promising method for evaluating cell proliferation and secretion in NET cell-line models. Compared to 2D models, 3D models grow relatively serum independent. In 3D model, SST-D2R multi-receptor targeting drugs inhibit CgA and serotonin secretion, but not NET cell growth.
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http://dx.doi.org/10.1530/ERC-19-0086DOI Listing
June 2019

Somatostatin Analogue Treatment Primarily Induce miRNA Expression Changes and Up-Regulates Growth Inhibitory miR-7 and miR-148a in Neuroendocrine Cells.

Genes (Basel) 2018 Jul 4;9(7). Epub 2018 Jul 4.

Center for Genomic Medicine, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark.

Somatostatin (SST) analogues are used to control the proliferation and symptoms of neuroendocrine tumors (NETs). MicroRNAs (miRNA) are small non-coding RNAs that modulate posttranscriptional gene expression. We wanted to characterize the miRNAs operating under the control of SST to elucidate to what extent they mediate STT actions. NCI-H727 carcinoid cell line was treated with either a chimeric SST/dopamine analogue; a SST or dopamine analogue for proliferation assays and for identifying differentially expressed miRNAs using miRNA microarray. The miRNAs induced by SST analogue treatment are investigated in carcinoid cell lines NCI-H727 and CNDT2 using in situ hybridization, qPCR and proliferation assays. SST analogues inhibited the growth of carcinoid cells more potently compared to the dopamine analogue. Principal Component Analysis (PCA) of the samples based on miRNA expression clearly separated the samples based on treatment. Two miRNAs which were highly induced by SST analogues, miR-7 and miR-148a, were shown to inhibit the proliferation of NCI-H727 and CNDT2 cells. SST analogues also produced a general up-regulation of the let-7 family members. SST analogues control and induce distinct miRNA expression patterns among which miR-7 and miR-148a both have growth inhibitory properties.
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http://dx.doi.org/10.3390/genes9070337DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6070923PMC
July 2018

In1-ghrelin splicing variant is associated with reduced disease-free survival of breast cancer patients and increases malignancy of breast cancer cells lines.

Carcinogenesis 2018 03;39(3):447-457

Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain.

Ghrelin gene generates several variants that regulate multiple pathophysiological functions, including tumor-related processes. In1-ghrelin is a splicing variant that was previously shown to be overexpressed in breast cancer (BCa), where it correlated with proliferation markers; however, its possible association with clinical outcome of BCa patients and underlying mechanisms are still unknown. To address this issue, expression levels and clinical associations of In1-ghrelin were analyzed in a cohort of 117 BCa samples. Additionally, a battery of cellular and molecular assays was implemented using two BCa cell lines (MCF-7 and MDA-MB-231), wherein the role of In1-ghrelin on proliferation, migration, dedifferentiation and signaling pathways was explored. The results generated revealed that high expression of In1-ghrelin in BCa samples was associated with lymph node metastasis and reduced disease-free survival. Indeed, In1-ghrelin overexpression stimulated proliferation and migration in MCF-7 and MDA-MB-231 cells. Similar results were found by treating MDA-MB-231 and MCF-7 with In1-ghrelin-derived peptides. Conversely, In1-ghrelin silencing decreased proliferation and migration capacities of MDA-MB-231. Furthermore, In1-ghrelin (but not ghrelin) overexpression increased the capacity to form mammospheres in both cell lines. These effects could be associated with activation of MAPK-ERK, Jag1/Notch, Wnt/β-catenin and/or TGF-β1 pathways. Altogether, our data indicate that In1-ghrelin could play relevant functional roles in the regulation of BCa development and progression and may provide insights to identify novel biomarkers and new therapeutic approaches for this pathology.
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http://dx.doi.org/10.1093/carcin/bgx146DOI Listing
March 2018

The oncogenic role of the In1-ghrelin splicing variant in prostate cancer aggressiveness.

Mol Cancer 2017 08 29;16(1):146. Epub 2017 Aug 29.

Maimonides Institute of Biomedical Research of Cordoba (IMIBIC), Córdoba, Spain.

Background: The Ghrelin-system is a complex, pleiotropic family composed of several peptides, including native-ghrelin and its In1-ghrelin splicing variant, and receptors (GHSR 1a/b), which are dysregulated in various endocrine-related tumors, where they associate to pathophysiological features, but the presence, functional role, and mechanisms of actions of In1-ghrelin splicing variant in prostate-cancer (PCa), is completely unexplored. Herein, we aimed to determine the presence of key ghrelin-system components (native-ghrelin, In1-ghrelin, GHSR1a/1b) and their potential pathophysiological role in prostate cancer (PCa).

Methods: In1-ghrelin and native-ghrelin expression was evaluated by qPCR in prostate tissues from patients with high PCa-risk (n = 52; fresh-tumoral biopsies), and healthy-prostates (n = 12; from cystoprostatectomies) and correlated with clinical parameters using Spearman-test. In addition, In1-ghrelin and native-ghrelin was measured in plasma from an additional cohort of PCa-patients with different risk levels (n = 30) and control-healthy patients (n = 20). In vivo functional (proliferation/migration) and mechanistic (gene expression/signaling-pathways) assays were performed in PCa-cell lines in response to In1-ghrelin and native-ghrelin treatment, overexpression and/or silencing. Finally, tumor progression was monitored in nude-mice injected with PCa-cells overexpressing In1-ghrelin, native-ghrelin and empty vector (control).

Results: In1-ghrelin, but not native-ghrelin, was overexpressed in high-risk PCa-samples compared to normal-prostate (NP), and this expression correlated with that of PSA. Conversely, GHSR1a/1b expression was virtually absent. Remarkably, plasmatic In1-ghrelin, but not native-ghrelin, levels were also higher in PCa-patients compared to healthy-controls. Furthermore, In1-ghrelin treatment/overexpression, and to a much lesser extent native-ghrelin, increased aggressiveness features (cell-proliferation, migration and PSA secretion) of NP and PCa cells. Consistently, nude-mice injected with PC-3-cells stably-transfected with In1-ghrelin, but not native-ghrelin, presented larger tumors. These effects were likely mediated by ERK1/2-signaling activation and involved altered expression of key oncogenes/tumor suppressor genes. Finally, In1-ghrelin silencing reduced cell-proliferation and PSA secretion from PCa cells.

Conclusions: Altogether, our results indicate that In1-ghrelin levels (in tissue) and circulating levels (in plasma) are increased in PCa where it can regulate key pathophysiological processes, thus suggesting that In1-ghrelin may represent a novel biomarker and a new therapeutic target in PCa.
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http://dx.doi.org/10.1186/s12943-017-0713-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5576296PMC
August 2017

The oncogenic role of the spliced somatostatin receptor sst5TMD4 variant in prostate cancer.

FASEB J 2017 11 13;31(11):4682-4696. Epub 2017 Jul 13.

Maimonides Institute of Biomedical Research of Córdoba (IMIBIC), Cordoba, Spain;

sst5TMD4, a splice variant of the sst5 gene, is overexpressed and associated with aggressiveness in various endocrine-related tumors, but its presence, functional role, and mechanisms of actions in prostate cancer (PCa)-the most common cancer type in males-is completely unexplored. In this study, formalin-fixed, paraffin-embedded prostate pieces from patients with localized PCa, which included tumoral and nontumoral adjacent regions ( = 45), fresh biopsies from patients with high-risk PCa ( = 52), and healthy fresh prostates from cystoprostatectomies ( = 14) were examined. In addition, PCa cell lines and xenograft models were used to determine the presence and functional role of sst5TMD4. Results demonstrated that sst5TMD4 is overexpressed (mRNA/protein) in PCa samples, and this is especially drastic in metastatic and/or high Gleason score tumor samples. Remarkably, sst5TMD4 expression was associated with an altered frequency of 2 single-nucleotide polymorphisms: rs197055 and rs12599155. In addition, PCa cell lines and xenograft models were used to demonstrate that sst5TMD4 overexpression increases cell proliferation and migration in PCa cells and induces larger tumors in nude mice, whereas its silencing decreased proliferation and migration. Remarkably, sst5TMD4 overexpression activated multiple intracellular pathways (ERK/JNK, MYC/MAX, WNT, retinoblastoma), altered oncogenes and tumor suppressor gene expression, and disrupted the normal response to somatostatin analogs in PCa cells. Altogether, we demonstrate that sst5TMD4 is overexpressed in PCa, especially in those patients with a worse prognosis, and plays an important pathophysiologic role in PCa, which suggesting its potential as a biomarker and/or therapeutic target.-Hormaechea-Agulla, D., Jiménez-Vacas, J. M., Gómez-Gómez, E., L.-López, F., Carrasco-Valiente, J., Valero-Rosa, J., Moreno, M. M., Sánchez-Sánchez, R., Ortega-Salas, R., Gracia-Navarro, F., Culler, M. D., Ibáñez-Costa, A., Gahete, M. D., Requena, M. J., Castaño, J. P., Luque, R. M. The oncogenic role of the spliced somatostatin receptor sst5TMD4 variant in prostate cancer.
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http://dx.doi.org/10.1096/fj.201601264RRRDOI Listing
November 2017

BIM-23A760 influences key functional endpoints in pituitary adenomas and normal pituitaries: molecular mechanisms underlying the differential response in adenomas.

Sci Rep 2017 02 9;7:42002. Epub 2017 Feb 9.

Maimonides Institute of Biomedical Research of Cordoba (IMIBIC); 14004 Cordoba, Spain.

Chimeric somatostatin/dopamine compounds such as BIM-23A760, an sst2/sst5/D receptors-agonist, have emerged as promising new approaches to treat pituitary adenomas. However, information on direct in vitro effects of BIM-23A760 in normal and tumoral pituitaries remains incomplete. The objective of this study was to analyze BIM-23A760 effects on functional parameters (Ca signaling, hormone expression/secretion, cell viability and apoptosis) in pituitary adenomas (n = 74), and to compare with the responses of normal primate and human pituitaries (n = 3-5). Primate and human normal pituitaries exhibited similar sst2/sst5/D2 expression patterns, wherein BIM-23A760 inhibited the expression/secretion of several pituitary hormones (specially GH/PRL), which was accompanied by increased sst2/sst5/D2 expression in primates and decreased Ca concentration in human cells. In tumoral pituitaries, BIM-23A760 also inhibited Ca concentration, hormone secretion/expression and proliferation. However, BIM-23A760 elicited stimulatory effects in a subset of GHomas, ACTHomas and NFPAs in terms of Ca signaling and/or hormone secretion, which was associated with the relative somatostatin/dopamine-receptors levels, especially sst5 and sst5TMD4. The chimeric sst2/sst5/D compound BIM-23A760 affects multiple, clinically relevant parameters on pituitary adenomas and may represent a valuable therapeutic tool. The relative ssts/D expression profile, particularly sst5 and/or sst5TMD4 levels, might represent useful molecular markers to predict the ultimate response of pituitary adenomas to BIM-23A760.
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http://dx.doi.org/10.1038/srep42002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5299479PMC
February 2017

The truncated somatostatin receptor sst5TMD4 stimulates the angiogenic process and is associated to lymphatic metastasis and disease-free survival in breast cancer patients.

Oncotarget 2016 Sep;7(37):60110-60122

Maimonides Institute for Biomedical Research of Cordoba (IMIBIC), Cordoba, Spain.

The truncated somatostatin receptor sst5TMD4 is associated with poor prognosis in breast cancer and increases breast cancer cell malignancy. Here, we examined the cellular/molecular mechanisms underlying this association, aiming to identify new molecular tools to improve diagnosis, prognosis or therapy. A gene expression array comparing sst5TMD4 stably-transfected MCF-7 cells and their controls (empty-plasmid) revealed the existence of profound alterations in the expression of genes involved in key tumoral processes, such as cell survival or angiogenesis. Moreover, sst5TMD4-overexpressing MCF-7 and MDA-MB-231 cells demonstrated increased expression/production of pro-angiogenic factors and enhanced capacity to form mammospheres. Consistently, sst5TMD4-expressing MCF-7 cells induced xenografted tumors with higher VEGF levels and elevated number of blood vessels. Importantly, sst5TMD4 was expressed in a subset of breast cancers, where it correlated with angiogenic markers, lymphatic metastasis, and reduced disease-free survival. These results, coupled to our previous data, support a relevant role of sst5TMD4 in the angiogenic process and reinforce the role of sst5TMD4 in breast cancer malignancy and metastatic potential, supporting its possible utility to develop new molecular biomarkers and drug therapies for these tumors.
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http://dx.doi.org/10.18632/oncotarget.11076DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5312372PMC
September 2016

Presence of sst5TMD4, a truncated splice variant of the somatostatin receptor subtype 5, is associated to features of increased aggressiveness in pancreatic neuroendocrine tumors.

Oncotarget 2016 Feb;7(6):6593-608

Department of Cell Biology, Physiology and Immunology, University of Cordoba, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Hospital Universitario Reina Sofia, and CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba 14014, Spain.

Purpose: Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rare and heterogeneous tumors, and their biological behavior is not well known. We studied the presence and potential functional roles of somatostatin receptors (sst1-5), focusing particularly on the truncated variants (sst5TMD4, sst5TMD5) and on their relationships with the angiogenic system (Ang/Tie-2 and VEGF) in human GEP-NETs.

Experimental Design: We evaluated 42 tumor tissue samples (26 primary/16 metastatic) from 26 patients with GEP-NETs, and 30 non-tumoral tissues (26 from adjacent non-tumor regions and 4 from normal controls) from a single center. Expression of sst1-5, sst5TMD4, sst5TMD5, Ang1-2, Tie-2 and VEGF was analyzed using real-time qPCR, immunofluorescence and immunohistochemistry. Expression levels were associated with tumor characteristics and clinical outcomes. Functional role of sst5TMD4 was analyzed in GEP-NET cell lines.

Results: sst1 exhibited the highest expression in GEP-NET, whilst sst2 was the most frequently observed sst-subtype (90.2%). Expression levels of sst1, sst2, sst3, sst5TMD4, and sst5TMD5 were significantly higher in tumor tissues compared to their adjacent non-tumoral tissue. Lymph-node metastases expressed higher levels of sst5TMD4 than in its corresponding primary tumor tissue. sst5TMD4 was also significantly higher in intestinal tumor tissues from patients with residual disease of intestinal origin compared to those with non-residual disease. Functional assays demonstrated that the presence of sst5TMD4 was associated to enhanced malignant features in GEP-NET cells. Angiogenic markers correlated positively with sst5TMD4, which was confirmed by immunohistochemical/fluorescence studies.

Conclusions: sst5TMD4 is overexpressed in GEP-NETs and is associated to enhanced aggressiveness, suggesting its potential value as biomarker and target in GEP-NETs.
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http://dx.doi.org/10.18632/oncotarget.6565DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4872735PMC
February 2016

In1-ghrelin, a splice variant of ghrelin gene, is associated with the evolution and aggressiveness of human neuroendocrine tumors: Evidence from clinical, cellular and molecular parameters.

Oncotarget 2015 Aug;6(23):19619-33

Servicio de Endocrinología y Nutrición, Hospital Universitario de la Princesa, Universidad Autónoma de Madrid, Instituto de Investigación Sanitaria Princesa, Madrid, España.

Ghrelin system comprises a complex family of peptides, receptors (GHSRs), and modifying enzymes [e.g. ghrelin-O-acyl-transferase (GOAT)] that control multiple pathophysiological processes. Aberrant alternative splicing is an emerging cancer hallmark that generates altered proteins with tumorigenic capacity. Indeed, In1-ghrelin and truncated-GHSR1b splicing variants can promote development/progression of certain endocrine-related cancers. Here, we determined the expression levels of key ghrelin system components in neuroendocrine tumor (NETs) and explored their potential functional role. Twenty-six patients with NETs were prospectively/retrospectively studied [72 samples from primary and metastatic tissues (30 normal/42 tumors)] and clinical data were obtained. The role of In1-ghrelin in aggressiveness was studied in vitro using NET cell lines (BON-1/QGP-1). In1-ghrelin, GOAT and GHSR1a/1b expression levels were elevated in tumoral compared to normal/adjacent tissues. Moreover, In1-ghrelin, GOAT, and GHSR1b expression levels were positively correlated within tumoral, but not within normal/adjacent samples, and were higher in patients with progressive vs. with stable/cured disease. Finally, In1-ghrelin increased aggressiveness (e.g. proliferation/migration) of NET cells. Altogether, our data strongly suggests a potential implication of ghrelin system in the pathogenesis and/or clinical outcome of NETs, and warrant further studies on their possible value for the future development of molecular biomarkers with diagnostic/prognostic/therapeutic value.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4637309PMC
http://dx.doi.org/10.18632/oncotarget.4316DOI Listing
August 2015

In1-ghrelin splicing variant is overexpressed in pituitary adenomas and increases their aggressive features.

Sci Rep 2015 Mar 4;5:8714. Epub 2015 Mar 4.

Department of Cell Biology, Physiology and Immunology, University of Cordoba, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Hospital Universitario Reina Sofia; CIBER Fisiopatología de la Obesidad y Nutrición; and Campus de Excelencia Internacional Agroalimentario (ceiA3), 14014 Córdoba, Spain.

Pituitary adenomas comprise a heterogeneous subset of pathologies causing serious comorbidities, which would benefit from identification of novel, common molecular/cellular biomarkers and therapeutic targets. The ghrelin system has been linked to development of certain endocrine-related cancers. Systematic analysis of the presence and functional implications of some components of the ghrelin system, including native ghrelin, receptors and the recently discovered splicing variant In1-ghrelin, in human normal pituitaries (n = 11) and pituitary adenomas (n = 169) revealed that expression pattern of ghrelin system suffers a clear alteration in pituitary adenomasas compared with normal pituitary, where In1-ghrelin is markedly overexpressed. Interestingly, in cultured pituitary adenoma cells In1-ghrelin treatment (acylated peptides at 100 nM; 24-72 h) increased GH and ACTH secretion, Ca(2+) and ERK1/2 signaling and cell viability, whereas In1-ghrelin silencing (using a specific siRNA; 100 nM) reduced cell viability. These results indicate that an alteration of the ghrelin system, specially its In1-ghrelin variant, could contribute to pathogenesis of different pituitary adenomas types, and suggest that this variant and its related ghrelin system could provide new tools to identify novel, more general diagnostic, prognostic and potential therapeutic targets in pituitary tumors.
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http://dx.doi.org/10.1038/srep08714DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4649711PMC
March 2015

Truncated somatostatin receptor variant sst5TMD4 confers aggressive features (proliferation, invasion and reduced octreotide response) to somatotropinomas.

Cancer Lett 2015 Apr 28;359(2):299-306. Epub 2015 Jan 28.

Department of Cell Biology, Physiology and Immunology, University of Cordoba, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), and Hospital Universitario Reina Sofia.; CIBER Fisiopatología de la Obesidad y Nutrición; Campus de Excelencia Internacional Agroalimentario (ceiA3), 14014, Córdoba, Spain. Electronic address:

The GH/IGF1 response of somatotropinomas to somatostatin analogues (SSA) is associated with their pattern of somatostatin receptor (sst1-sst5) expression. Recently, we demonstrated that expression of a truncated sst5-variant (sst5TMD4) can influence the secretory response of somatotropinomas to SSA-therapy; however, its potential relationship with aggressive features (e.g. invasion/proliferation) is still unknown. Here, we show that sst5TMD4 is present in 50% of non-functioning pituitary-adenomas (NFPA) (n = 30) and 89% of somatotropinomas (n = 36), its expression levels being highest in somatotropinomas > > NFPAs > > > normal pituitaries (negligible expression; n = 8). In somatotropinomas, sst5TMD4 mRNA and protein levels correlated positively, and its expression was directly associated with tumor invasiveness (cavernous/sphenoid sinus), and inversely correlated with age and GH/IGF1 reduction after 3-6 months with octreotide-LAR therapy. GNAS+ somatotropinomas expressed lower sst5TMD4 levels. ROC analysis revealed sst5TMD4 expression as the only marker, within all sst-subtypes, capable to predict tumor invasiveness in somatotropinomas. sst5TMD4 overexpression increased cell viability in cultured somatotropinoma (n = 5). Hence, presence of sst5TMD4 associates with increased aggressive features and worse prognosis in somatotropinomas, thereby providing a potentially useful tool to refine somatotropinoma diagnosis, predict outcome of clinical response to SSA-therapy and develop new therapeutic targets.
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http://dx.doi.org/10.1016/j.canlet.2015.01.037DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4378269PMC
April 2015

The truncated isoform of somatostatin receptor5 (sst5TMD4) is associated with poorly differentiated thyroid cancer.

PLoS One 2014 21;9(1):e85527. Epub 2014 Jan 21.

Department of Cell Biology, Physiology and Immunology University of Córdoba, Reina Sofía University Hospital, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Córdoba, Spain.

Somatostatin receptors (ssts) are expressed in thyroid cancer cells, but their biological significance is not well understood. The aim of this study was to assess ssts in well differentiated (WDTC) and poorly differentiated thyroid cancer (PDTC) by means of imaging and molecular tools and its relationship with the efficacy of somatostatin analog treatment. Thirty-nine cases of thyroid carcinoma were evaluated (20 PDTC and 19 WDTC). Depreotide scintigraphy and mRNA levels of sst-subtypes, including the truncated variant sst5TMD4, were carried out. Depreotide scans were positive in the recurrent tumor in the neck in 6 of 11 (54%) PDTC, and in those with lung metastases in 5/11 cases (45.4%); sst5TMD4 was present in 18/20 (90%) of PDTC, being the most densely expressed sst-subtype, with a 20-fold increase in relation to sst2. In WDTC, sst2 was the most represented, while sst5TMD4 was not found; sst2 was significantly increased in PDTC in comparison to WDTC. Five depreotide positive PDTC received octreotide for 3-6 months in a pilot study with no changes in the size of the lesions in 3 of them, and a significant increase in the pulmonary and cervical lesions in the other 2. All PDTC patients treated with octreotide showed high expression of sst5TMD4. ROC curve analysis demonstrated that only sst5TMD4 discriminates between PDTC and WDTC. We conclude that sst5TMD4 is overexpressed in PDTC and may be involved in the lack of response to somatostatin analogue treatment.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0085527PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3897452PMC
October 2014

Cortistatin attenuates inflammatory pain via spinal and peripheral actions.

Neurobiol Dis 2014 Mar 9;63:141-54. Epub 2013 Dec 9.

Institute of Parasitology and Biomedicine Lopez-Neyra, IPBLN-CSIC, 18016 Granada, Spain. Electronic address:

Clinical pain, as a consequence of inflammation or injury of peripheral organs (inflammatory pain) or nerve injury (neuropathic pain), represents a serious public health issue. Treatment of pain-related suffering requires knowledge of how pain signals are initially interpreted and subsequently transmitted and perpetuated. To limit duration and intensity of pain, inhibitory signals participate in pain perception. Cortistatin is a cyclic-neuropeptide that exerts potent inhibitory actions on cortical neurons and immune cells. Here, we found that cortistatin is a natural analgesic component of the peripheral nociceptive system produced by peptidergic nociceptive neurons of the dorsal root ganglia in response to inflammatory and noxious stimuli. Moreover, cortistatin is produced by GABAergic interneurons of deep layers of dorsal horn of spinal cord. By using cortistatin-deficient mice, we demonstrated that endogenous cortistatin critically tunes pain perception in physiological and pathological states. Furthermore, peripheral and spinal injection of cortistatin potently reduced nocifensive behavior, heat hyperalgesia and tactile allodynia in experimental models of clinical pain evoked by chronic inflammation, surgery and arthritis. The analgesic effects of cortistatin were independent of its anti-inflammatory activity and directly exerted on peripheral and central nociceptive terminals via Gαi-coupled somatostatin-receptors (mainly sstr2) and blocking intracellular signaling that drives neuronal plasticity including protein kinase A-, calcium- and Akt/ERK-mediated release of nociceptive peptides. Moreover, cortistatin could modulate, through its binding to ghrelin-receptor (GHSR1), pain-induced sensitization of secondary neurons in spinal cord. Therefore, cortistatin emerges as an anti-inflammatory factor with potent analgesic effects that offers a new approach to clinical pain therapy, especially in inflammatory states.
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http://dx.doi.org/10.1016/j.nbd.2013.11.022DOI Listing
March 2014

Cortistatin inhibits migration and proliferation of human vascular smooth muscle cells and decreases neointimal formation on carotid artery ligation.

Circ Res 2013 May 17;112(11):1444-55. Epub 2013 Apr 17.

Department of Immunology and Cell Biology, Institute of Parasitology and Biomedicine Lopez-Neyra, CSIC, Granada, Spain.

Rationale: Proliferation and migration of smooth muscle cells (SMCs) are key steps for the progression of atherosclerosis and restenosis. Cortistatin is a multifunctional neuropeptide belonging to the somatostatin family that exerts unique functions in the nervous and immune systems. Cortistatin is elevated in plasma of patients experiencing coronary heart disease and attenuates vascular calcification.

Objective: To investigate the occurrence of vascular cortistatin and its effects on the proliferation and migration of SMCs in vitro and in vivo and to delimitate the receptors and signal transduction pathways governing its actions.

Methods And Results: SMCs from mouse carotid and human aortic arteries and from human atherosclerotic plaques highly expressed cortistatin. Cortistatin expression positively correlated with the progression of arterial intima hyperplasia. Cortistatin inhibited platelet-derived growth factor-stimulated proliferation of human aortic SMCs via binding to somatostatin receptors (sst2 and sst5) and ghrelin receptor, induction of cAMP and p38-mitogen-activated protein kinase, and inhibition of Akt activity. Moreover, cortistatin impaired lamellipodia formation and migration of human aortic SMCs toward platelet-derived growth factor by inhibiting, in a ghrelin-receptor-dependent manner, Rac1 activation and cytosolic calcium increases. These effects on SMC proliferation and migration correlated with an inhibitory action of cortistatin on the neointimal formation in 2 models of carotid arterial ligation. Endogenous cortistatin seems to play a critical role in regulating SMC function because cortistatin-deficient mice developed higher neointimal hyperplasic lesions than wild-type mice.

Conclusions: Cortistatin emerges as a natural endogenous regulator of SMCs under pathological conditions and an attractive candidate for the pharmacological management of vascular diseases that course with neointimal lesion formation.
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http://dx.doi.org/10.1161/CIRCRESAHA.112.300695DOI Listing
May 2013

Effect of application route of the ghrelin analog BIM-28131 (RM-131) on body weight and body composition in a rat heart failure model.

Int J Cardiol 2013 Oct 7;168(3):2369-74. Epub 2013 Mar 7.

Applied Cachexia Research, Dept. of Cardiology, Charité Medical School, Berlin, Germany; Center for Cardiovascular Research, Charité Medical School, Berlin, Germany.

Chronic heart failure (CHF) remains one of the most challenging diseases in terms of numbers and disease management, particularly so, if the CHF patient develops cardiac cachexia. Ghrelin and its analogs have been suggested to improve body weight and cardiac function in heart failure models and exploratory human clinical studies. However, most ghrelin compounds are peptides and need to be injected several times per day, which affects the quality of life of patients. Here, we compared two application routes, three times daily subcutaneous (sc) injections to continuous infusion using osmotic mini-pumps in a rat model of CHF. Moreover, the effects were also compared to three times daily sc injections of growth hormone (GH). Rats were treated for 28 d. The results show that treatment with 50 or 100 nmol/kg/d BIM-28131 (RM-131) potently induces body weight gain, fat and lean mass compared to placebo. The gain of lean mass was equal to the gain of lean mass in the 2mg/kg/d GH group and superior to 250 μg/kg/d GH. Both GH and BIM-28131 increased levels of insulin-like growth factor-1 to a similar extent. Little effect was seen on cardiac function; only cardiac output was improved by either high dose BIM-28131 or GH. Overall the effects of BIM-28131 were similar in both application routes.
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http://dx.doi.org/10.1016/j.ijcard.2013.01.263DOI Listing
October 2013

Chronic treatment with a melanocortin-4 receptor agonist causes weight loss, reduces insulin resistance, and improves cardiovascular function in diet-induced obese rhesus macaques.

Diabetes 2013 Feb 9;62(2):490-7. Epub 2012 Oct 9.

Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, Portland, Oregon, USA.

The melanocortin-4 receptor (MC4R) is well recognized as an important mediator of body weight homeostasis. Activation of MC4R causes dramatic weight loss in rodent models, and mutations in human are associated with obesity. This makes MC4R a logical target for pharmacological therapy for the treatment of obesity. However, previous studies in rodents and humans have observed a broad array of side effects caused by acute treatment with MC4R agonists, including increased heart rate and blood pressure. We demonstrate that treatment with a highly-selective novel MC4R agonist (BIM-22493 or RM-493) resulted in transient decreases in food intake (35%), with persistent weight loss over 8 weeks of treatment (13.5%) in a diet-induced obese nonhuman primate model. Consistent with weight loss, these animals significantly decreased adiposity and improved glucose tolerance. Importantly, we observed no increases in blood pressure or heart rate with BIM-22493 treatment. In contrast, treatment with LY2112688, an MC4R agonist previously shown to increase blood pressure and heart rate in humans, caused increases in blood pressure and heart rate, while modestly decreasing food intake. These studies demonstrate that distinct melanocortin peptide drugs can have widely different efficacies and side effects.
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http://dx.doi.org/10.2337/db12-0598DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3554387PMC
February 2013

Adamantyl carboxamides and acetamides as potent human 11β-hydroxysteroid dehydrogenase type 1 inhibitors.

Bioorg Med Chem 2012 Nov 12;20(21):6394-402. Epub 2012 Sep 12.

Medicinal Chemistry, Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, UK.

The modulation of 11β-HSD1 activity with selective inhibitors has beneficial effects on various metabolic disorders including insulin resistance, dyslipidemia and obesity. Here we report the discovery of a series of novel adamantyl carboxamide and acetamide derivatives as selective inhibitors of human 11β-HSD1 in HEK-293 cells transfected with the HSD11B1 gene. Optimization based on an initially identified 11β-HSD1 inhibitor (3) led to the discovery of potent inhibitors with IC(50) values in the 100 nM range. These compounds are also highly selective 11β-HSD1 inhibitors with no activity against 11β-HSD2 and 17β-HSD1. Compound 15 (IC(50)=114 nM) with weak inhibitory activity against the key human cytochrome P450 enzymes and moderate stability in incubation with human liver microsomes is worthy of further development. Importantly, compound 41 (IC(50)=280 nM) provides a new lead that incorporates an adamantyl group surrogate and should enable further series diversification.
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http://dx.doi.org/10.1016/j.bmc.2012.08.056DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3510433PMC
November 2012

Effect of ghrelin and its analogues, BIM-28131 and BIM-28125, on the expression of myostatin in a rat heart failure model.

J Cachexia Sarcopenia Muscle 2013 Mar 18;4(1):63-9. Epub 2012 Sep 18.

Heart Center Leipzig, Clinic of Cardiology, University Leipzig, Strümpellstrasse 39, 04289, Leipzig, Germany,

Background: In chronic heart failure (CHF), cachexia is a hallmark of the terminal stage of this disease and is associated with a severely reduced quality of life and poor prognosis. Therapeutic options are currently not available. Ghrelin and its analogues BIM-28125 and BIM-28131 (now known as RM-131) have been shown to increase weight in a rat model of CHF. It has been further demonstrated that the expression of myostatin, a negative regulator of skeletal muscle mass, is increased in CHF. The aim of the study was to investigate the influence of ghrelin or its analogues on myostatin in CHF.

Methods: In an animal model of CHF, Sprague-Dawley rats received either ghrelin or two ghrelin analogues BIM-28125 and BIM-28131 in two different concentrations (50 and 500 nmol/kg/day) compared to placebo. The compounds were delivered using osmotic mini pumps. The expression of myostatin was analyzed in skeletal muscle by RT-PCR and Western blot, and muscle mass of gastrocnemius muscle was measured. The plasma levels of tumor necrosis factor alpha (TNF-α) were measured.

Results: The relative weight of the gastrocnemius muscle of the sham-operated group was significantly increased compared to placebo-treated CHF rats. The application of ghrelin analogue BIM-28125 and BIM-28131 in their higher concentrations led to a significant reduction in myostatin mRNA expression in comparison to placebo. Myostatin protein expression was significantly reduced in both concentrations of ghrelin and BIM-28131 and in the lower concentration of BIM-28125. The increase of TNF-α plasma concentration in the CHF-animals could be abolished by all used substances.

Conclusions: In an animal model of CHF, the expression of myostatin is significantly reduced in the skeletal muscle after application of ghrelin and most concentrations of its analogues BIM-28125 and BIM-28131 possibly due to anti-inflammatory effects.
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http://dx.doi.org/10.1007/s13539-012-0085-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3581616PMC
March 2013

Somatostatin analogs and chimeric somatostatin-dopamine molecules differentially regulate human growth hormone and prolactin gene expression and secretion in vitro.

Mol Cell Endocrinol 2012 Oct 15;362(1-2):104-9. Epub 2012 Jun 15.

Division of Endocrinology, Cedars-Sinai Research Institute, University of California School of Medicine, Los Angeles, CA 90048, USA.

We tested effects of selective somatostatin receptor 2 (SST2) agonist BIM-23120, SST5 agonist BIM-23206 and chimeric somatostatin-dopamine molecules (SRIF/DA) BIM-23A760 and BIM-23A761 on GH and PRL secretion and gene expression in human GH/PRL-secreting pituitary tumors in vitro. In "responders" group BIM-23120 suppressed GH levels by 26±4%, BIM-23206 by 31±5%, BIM-23A760 by 23±4%, BIM-23A761 by 39±8% and D(2)-dopamine agonist BIM-53097 by 31±5%. Using real-time PCR we demonstrated that GH inhibition was not accompanied by decreased GH mRNA levels. PRL secretion was inhibited by BIM-23A760 (29±5%), BIM-23A761 (34±4%), BIM-23206 (26±4%) and BIM-53097 (36±2%). SRIF/DA and BIM-53097 also suppressed PRL mRNA levels. Concluding, SST2 and SST5 agonists and SRIF/DA inhibit GH secretion, but do not suppress GH gene transcription. SRIF/DA and BIM-53097 inhibit both PRL secretion and PRL gene expression. SST5 agonist inhibits PRL secretion, but does not suppress PRL gene expression. D(2) affinity is crucial in SRIF/DA action on PRL gene expression.
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http://dx.doi.org/10.1016/j.mce.2012.05.020DOI Listing
October 2012

Adropin deficiency is associated with increased adiposity and insulin resistance.

Obesity (Silver Spring) 2012 Jul 9;20(7):1394-402. Epub 2012 Feb 9.

Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, FL, USA.

Adropin is a secreted peptide that improves hepatic steatosis and glucose homeostasis when administered to diet-induced obese mice. It is not clear if adropin is a peptide hormone regulated by signals of metabolic state. Moreover, the significance of a decline in adropin expression with obesity with respect to metabolic disease is also not clear. We investigated the regulation of serum adropin by metabolic status and diet. Serum adropin levels were high in chow-fed conditions and were suppressed by fasting and diet-induced obesity (DIO). High adropin levels were observed in mice fed a high-fat low carbohydrate diet, whereas lower levels were observed in mice fed a low-fat high carbohydrate diet. To investigate the role of adropin deficiency in metabolic homeostasis, we generated adropin knockout mice (AdrKO) on the C57BL/6J background. AdrKO displayed a 50%-increase in increase in adiposity, although food intake and energy expenditure were normal. AdrKO also exhibited dyslipidemia and impaired suppression of endogenous glucose production (EndoR(a)) in hyperinsulinemic-euglycemic clamp conditions, suggesting insulin resistance. While homo- and heterozygous carriers of the null adropin allele exhibited normal DIO relative to controls, impaired glucose tolerance associated with weight gain was more severe in both groups. In summary, adropin is a peptide hormone regulated by fasting and feeding. In fed conditions, adropin levels are regulated dietary macronutrients, and increase with dietary fat content. Adropin is not required for regulating food intake, however, its functions impact on adiposity and are involved in preventing insulin resistance, dyslipidemia, and impaired glucose tolerance.
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http://dx.doi.org/10.1038/oby.2012.31DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3905465PMC
July 2012

Ghrelin and its analogues, BIM-28131 and BIM-28125, improve body weight and regulate the expression of MuRF-1 and MAFbx in a rat heart failure model.

PLoS One 2011 15;6(11):e26865. Epub 2011 Nov 15.

Applied Cachexia Research, Department of Cardiology, Charité Medical School, Berlin, Germany.

Unlabelled: Cardiac cachexia is a serious complication of chronic heart failure with a prevalence of 10-16% and poor prognosis. There are no current therapy options for cardiac cachexia. Ghrelin is the natural ligand for the GHS-1a-receptor and a potential target for conditions associated with cachexia. Ghrelin has been shown to increase weight in several species. The GHS-1a-receptor is not only found in the brain, but also in other tissues, including the myocardium. Human clinical trials with native ghrelin in cardiac cachexia demonstrated increases in appetite, weight and cardiac output.

Methods: Human ghrelin or one of two analogues BIM-28125 and BIM-28131 (also known as RM-131) were tested at 50 nmole/kg/d and 500 nmole/kg/d versus placebo in a rat model of heart failure (myocardial infarction). Animals (SD-rats, approx. 225 g at surgery) received diuretics from day 14 and compounds from day 28 for 4 weeks using osmotic pumps. Weight was monitored and body composition analysed (NMR-scanning). Cardiac function was assessed by echocardiography and hemodynamics.

Results: Animals with MI gained less weight compared to sham rats until start of the therapy (311 g vs 324 g, p = 0.0129). Animals treated with BIM-28131 at 50 nmole/kg/d or all compounds at 500 nmole/kg/d displayed stronger weight gain compared to placebo and sham (all p<0.001). Before treatment, body composition was similar in all groups (average: 36 g fat, 248 g lean). Placebo-treated rats gained no fat, but only lean mass. The active compounds induced both fat and lean mass gain, but to a different extent. The fat-to-muscle-ratio of tissue gain was 0.9±0.07 for BIM-28131 at 50 nmole/kg/d, whereas at 500 nmole/kg/d it was 0.76±0.07 for BIM-28131, 0.68±0.12 for BIM-28125, and 0.48±0.05 for ghrelin. MuRF-1 and MAFbx were differentially regulated by treatment.

Conclusion: Ghrelin is a very promising treatment option for cardiac cachexia, with the analogue BIM-28131 (RM-131) being the most effective compound.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0026865PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3216926PMC
May 2012

Balance between somatostatin and D2 receptor expression drives TSH-secreting adenoma response to somatostatin analogues and dopastatins.

Clin Endocrinol (Oxf) 2012 Mar;76(3):407-14

Department of Internal Medicine & Center of Excellence for Biomedical Research, University of Genoa, Viale Benedetto XV 2, Genoa, Italy.

Context: First-line therapy for thyrotropin-secreting pituitary adenomas (TSHomas) is neurosurgery, while medical treatment rests mainly on somatostatin analogues. Clinically available sst(2) -preferring analogues, octreotide and lanreotide, induce normalization of hormone levels in approximately 90% of patients and tumour shrinkage in 45%.

Objective: We evaluated somatostatin 1, 2, 3 and 5 and dopamine D2 receptor expression in tumour samples from three TSHomas, and the relationships between receptor expression, in vitro antiproliferative response and clinical data, including octreotide test and three months of therapy with octreotide long-acting repeatable (LAR). TSHoma cell proliferation was tested in vitro using octreotide, cabergoline and two chimeric compounds, BIM-23A760 and BIM-23A387.

Results: All patients showed significant TSH lowering to acute octreotide test, but a hormonal response to long-term treatment was observed in only two patients, showing a high sst(5) /sst(2) ratio. Patient 2, characterized by high expression of sst(2) and sst(1) and a relative lower expression of sst(5) , experienced tachyphylaxis after prolonged octreotide treatment. In vitro, the somatostatin/dopamine receptor agonist BIM-23A760 caused the highest antiproliferative effect among those tested. Combined treatment with octreotide and cabergoline displayed an additive effect of magnitude comparable to that of the other chimeric compound (BIM-23A387). Octreotide resistance was confirmed in cells isolated from the nonresponder patient, although it could be overcome by treatment with the chimeric compounds.

Conclusions:   A high sst(5) /sst(2) ratio might be predictive of a positive outcome to long-term treatment with somatostatin analogues in TSHomas. Moreover, combined somatostatin and D(2) receptor targeting might be considered as a potential tool to improve the response rate in octreotide-resistant tumours.
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http://dx.doi.org/10.1111/j.1365-2265.2011.04200.xDOI Listing
March 2012

Adamantyl ethanone pyridyl derivatives: potent and selective inhibitors of human 11β-hydroxysteroid dehydrogenase type 1.

ChemMedChem 2011 Sep 28;6(9):1616-29. Epub 2011 Jun 28.

Medicinal Chemistry, Department of Pharmacy and Pharmacology, University of Bath, Bath BA27AY, UK.

Elevated levels of active glucocorticoids have been implicated in the development of several phenotypes of metabolic syndrome, such as type 2 diabetes and obesity. 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) catalyses the intracellular conversion of inactive cortisone to cortisol. Selective 11β-HSD1 inhibitors have shown beneficial effects in various conditions, including diabetes, dyslipidemia and obesity. A series of adamantyl ethanone pyridyl derivatives has been identified, providing potent and selective inhibitors of human 11β-HSD1. Lead compounds display low nanomolar inhibition against human and mouse 11β-HSD1 and are selective for this isoform, with no activity against 11β-HSD2 and 17β-HSD1. Structure-activity relationship studies reveal that an unsubstituted pyridine tethered to an adamantyl ethanone motif through an ether or sulfoxide linker provides a suitable pharmacophore for activity. The most potent inhibitors have IC₅₀ values around 34-48 nM against human 11β-HSD1, display reasonable metabolic stability in human liver microsomes, and weak inhibition of key human CYP450 enzymes.
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http://dx.doi.org/10.1002/cmdc.201100182DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3179844PMC
September 2011

Discovery of adamantyl heterocyclic ketones as potent 11β-hydroxysteroid dehydrogenase type 1 inhibitors.

ChemMedChem 2011 Aug 23;6(8):1439-51. Epub 2011 May 23.

Medicinal Chemistry, Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath BA27AY, UK.

11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) plays a key role in converting intracellular cortisone to physiologically active cortisol, which is implicated in the development of several phenotypes of metabolic syndrome. Inhibition of 11β-HSD1 activity with selective inhibitors has beneficial effects on various conditions, including diabetes, dyslipidemia and obesity, and therefore constitutes a promising strategy to discover novel therapies for metabolic and cardiovascular diseases. A series of novel adamantyl heterocyclic ketones provides potent and selective inhibitors of human 11β-HSD1. Lead compounds display low nanomolar inhibition against human and mouse 11β-HSD1 and are selective with no activity against 11β-HSD2 and 17β-HSD1. Selected potent 11β-HSD1 inhibitors show moderate metabolic stability upon incubation with human liver microsomes and weak inhibition of human CYP450 enzymes.
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http://dx.doi.org/10.1002/cmdc.201100144DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3170876PMC
August 2011