scholarly journals Characterization of SNARE Proteins in Human Pituitary Adenomas: Targeted Secretion Inhibitors as a New Strategy for the Treatment of Acromegaly?

2013 ◽  
Vol 98 (12) ◽  
pp. E1918-E1926 ◽  
Author(s):  
Edwin A. Garcia ◽  
Giampaolo Trivellin ◽  
Elena D. Aflorei ◽  
Michael Powell ◽  
Joana Grieve ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Pituitary Adenoma ◽  
Pituitary Adenomas ◽  
Hormone Secretion ◽  
Snare Proteins ◽  
University Hospitals ◽  
Human Pituitary ◽  
Human Pituitary Adenoma ◽  
Gh Secretion ◽  
Ghrh Receptor

Context: Targeted secretion inhibitors (TSIs), a new class of recombinant biotherapeutic proteins engineered from botulinum toxin, represent a novel approach for treating diseases with excess secretion. They inhibit hormone secretion from targeted cell types through cleavage of SNARE (soluble N-ethylmaleimide-sensitive factor-activating protein receptor) proteins. qGHRH-LHN/D is a TSI targeting pituitary somatotroph through binding to the GHRH-receptor and cleavage of the vesicle-associated membrane protein (VAMP) family of SNARE proteins. Objective: Our objective was to study SNARE protein expression in pituitary adenomas and to inhibit GH secretion from somatotropinomas using qGHRH-LHN/D. Design: We analyzed human pituitary adenoma analysis for SNARE expression and response to qGHRH-LHN/D treatment. Setting: The study was conducted in University Hospitals. Patients: We used pituitary adenoma samples from 25 acromegaly and 47 nonfunctioning pituitary adenoma patients. Outcome: Vesicle-SNARE (VAMP1–3), target-SNARE (syntaxin1, SNAP-23, and SNAP-25), and GHRH-receptor detection with RT-qPCR, immunocytochemistry, and immunoblotting. Assessment of TSI catalytic activity on VAMPs and release of GH from adenoma cells. Results: SNARE proteins were variably expressed in pituitary samples. In vitro evidence using recombinant GFP-VAMP2&3 or pituitary adenoma lysates suggested sufficient catalytic activity of qGHRH-LHN/D to degrade VAMPs, but was unable to inhibit GH secretion in somatotropinoma cell cultures. Conclusions: SNARE proteins are present in human pituitary somatotroph adenomas that can be targeted by TSIs to inhibit GH secretion. qGHRH-LHN/D was unable to inhibit GH secretion from human somatotroph adenoma cells. Further studies are required to understand how the SNARE proteins drive GH secretion in human somatotrophs to allow the development of novel TSIs with a potential therapeutic benefit.

scholarly journals miR-26a Plays an Important Role in Cell Cycle Regulation in ACTH-Secreting Pituitary Adenomas by Modulating Protein Kinase Cδ

Endocrinology ◽  
2013 ◽  
Vol 154 (5) ◽  
pp. 1690-1700 ◽  
Author(s):  
Erica Gentilin ◽  
Federico Tagliati ◽  
Carlo Filieri ◽  
Daniela Molè ◽  
Mariella Minoia ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Pituitary Adenoma ◽  
Protein Kinase ◽  
Pituitary Adenomas ◽  
Viable Cell Number ◽  
Pituitary Cells ◽  
Human Pituitary ◽  
Human Pituitary Adenoma ◽  
Acth Secreting ◽  
Protein Kinase Cδ

Abstract The functional aftermath of microRNA (miRNA) dysregulation in ACTH-secreting pituitary adenomas has not been demonstrated. miRNAs represent diagnostic and prognostic biomarkers as well as putative therapeutic targets; their investigation may shed light on the mechanisms that underpin pituitary adenoma development and progression. Drugs interacting with such pathways may help in achieving disease control also in the settings of ACTH-secreting pituitary adenomas. We investigated the expression of 10 miRNAs among those that were found as most dysregulated in human pituitary adenoma tissues in the settings of a murine ACTH-secreting pituitary adenoma cell line, AtT20/D16v-F2. The selected miRNAs to be submitted to further investigation in AtT20/D16v-F2 cells represent an expression panel including 5 up-regulated and 5 down-regulated miRNAs. Among these, we selected the most dysregulated mouse miRNA and searched for miRNA targets and their biological function. We found that AtT20/D16v-F2 cells have a specific miRNA expression profile and that miR-26a is the most dysregulated miRNA. The latter is overexpressed in human pituitary adenomas and can control viable cell number in the in vitro model without involving caspase 3/7-mediated apoptosis. We demonstrated that protein kinase Cδ (PRKCD) is a direct target of miR-26a and that miR26a inhibition delays the cell cycle in G1 phase. This effect involves down-regulation of cyclin E and cyclin A expression via PRKCD modulation. miR-26a and related pathways, such as PRKCD, play an important role in cell cycle control of ACTH pituitary cells, opening new therapeutic possibilities for the treatment of persistent/recurrent Cushing's disease.

scholarly journals Stimulation by Urocortin of Growth Hormone (GH) Secretion in GH-Producing Human Pituitary Adenoma Cells.

1997 ◽  
Vol 44 (4) ◽  
pp. 627-629 ◽  
Author(s):  
YOSHIO MURAKAMI ◽  
TOSHIAKI MORI ◽  
KUNIO KOSHIMURA ◽  
MASAMICHI KUROSAKI ◽  
TOMOKATSU HORI ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Pituitary Adenoma ◽  
Human Pituitary ◽  
Human Pituitary Adenoma ◽  
Gh Secretion

Effect of bromocriptine, somatostatin, and oestradiol-17 β on hormone secretion and ultrastructure of human pituitary tumours in vitro

1981 ◽  
Vol 98 (1) ◽  
pp. 14-23 ◽  
Author(s):  
R. A. Prysor-Jones ◽  
S.J. Kennedy ◽  
J. P. O'Sullivan ◽  
J. S. Jenkins
Keyword(s):  
Pituitary Adenomas ◽  
Morphological Changes ◽  
Hormone Secretion ◽  
Prolactin Secretion ◽  
Human Pituitary ◽  
Gh Secretion ◽  
Human Pituitary Adenomas ◽  
Secretion Granules

Abstract. The effect of bromocriptine and somatostatin on hormone secretion and the ultrastructure of human pituitary adenomas was studied in vitro. Prolactin secretion was inhibited by bromocriptine in 3 out of 10 prolactin-secreting tumours and in explants from 2 normal pituitaries. GH secretion was reduced by bromocriptine in 4 out of 6 GH-secreting adenomas but was not affected by the drug in the incubations of normal pituitaries. Somatostatin inhibited GH secretion in 2 out of 5 pituitary adenomas and the effect was comparable with that of bromocriptine. Incubation of prolactin-secreting adenomas with oestradiol for as long as 24 days produced no change in hormone secretion. Examination of tumour explants by electron microscopy showed that somatostatin and bromocriptine produced accumulation of secretion granules but no changes in the secretory organelles. Long term bromocriptine treatment of 'nude' athymic mice bearing xenografts of human pituitary adenomas suppressed hormone secretion and produced some increase in secretion granules but there were no morphological changes in the secretory organelles or other vital structures of the adenoma cells.

scholarly journals Pituitary adenoma in aged rats. A case report

2018 ◽  
Vol 59 (1) ◽  
pp. 58
Author(s):  
M KATSIMPOULAS ◽  
M FOTEINOU ◽  
E PARONIS ◽  
P ALEXAKOS ◽  
N KOSTOMITSOPOULOS
Keyword(s):  
Pituitary Adenoma ◽  
Pituitary Adenomas ◽  
Large Scale ◽  
Laboratory Animals ◽  
Neoplastic Disease ◽  
Aged Rats ◽  
Human Pituitary ◽  
Human Pituitary Adenoma ◽  
Neoplastic Lesion ◽  
Toxicological Studies

The prevalence of neoplastic disease in the rat is well defined, because this species has been routinely used for decades in large-scale carcinogenic, aging and toxicological studies. Stock and strain-specific differences in the prevalence of some types of tumors are well documented. Pituitary adenoma is a neoplastic lesion which can be observed in older or aged rats of both sexes. In addition to sex, strain, diet, genetic factor, breeding history and accommodation may also play a role. Pituitary adenoma can also affect hamster, guinea pig and mice. The aim of this article is to report an incidence of pituitary adenomas, which was observed in a rat breeding colony of the Center for Experimental Surgery of the Biomedical Research Foundation of the Academy of Athens. During the clinical examination five female Wistar rats, at the age of 18 to 24 months old, expressed anorexia, weight loss, ataxia and bilateral blindness. At necropsy, the pituitary gland was enlarged with lobulations, often dark red to brown and hemorrhagic in appearance. In some cases there was a marked compression of the overlying mesencephalon. Histological examination with haematoxylin-eosin were observed cords and nests of glandular cells bound by strands of connective tissue, with an abundant capillary network. On immunohistochemical examination were observed strong positive reaction of synaptophysin. Findings were similar to pituitary adenoma. Pituitary adenoma is a serious non-reversible disease leading to the death of the animal. Laboratory animals with pituitary adenomas can be used as models in research of human pituitary adenoma.

IL-18 expression in clinical human pituitary adenoma

2021 ◽  
pp. 1-6
Author(s):  
Qi Shao ◽  
Ning Liu ◽  
Guo-Fu Li ◽  
Qian-Cheng Meng ◽  
Jia-Hao Yao ◽  
...  
Keyword(s):  
Pituitary Adenoma ◽  
Mrna Expression ◽  
Pituitary Adenomas ◽  
Adrenocorticotropic Hormone ◽  
Pituitary Tumors ◽  
Thyroid Stimulating Hormone ◽  
Mrna Levels ◽  
Human Pituitary ◽  
Human Pituitary Adenoma ◽  
Real Time Quantitative Pcr

BACKGROUND: IL-18 is known as an interferon-inducing factor that belongs to the IL-1 family, and is synthesized as an inactive precursor protein. OBJECTIVE: The present study aims to investigate the expression of IL-18, IL-18R, R and IL-18 binding protein (BP) mRNA in various types of human pituitary tumors, such as adrenocorticotropic hormone (ACTH), growth hormone (GH), prolactin (PRL), thyroid stimulating hormone (TSH)-producing adenomas and non-function adenomas. METHODS: Pituitary adenoma tissues were obtained during the surgery of 41 patients: nine patients had ACTH-producing pituitary adenomas, nine patients had GH-producing pituitary adenomas, five patients had TSH-producing pituitary adenomas, seven patients had PRL-producing pituitary adenomas, and 11 patients had non-functioning adenomas. The mRNA expression levels of IL-18, IL-18BP, IL-18R and IL-18R were quantified using real-time quantitative PCR. RESULTS: The mRNA expression of IL-18 was significantly higher in ACTH-, GH- and PRL-producing adenomas, when compared to non-function tumors. Similarly, a significantly higher mRNA expression of IL-18BP and IL-18R was observed in ACTH-, GH- and PRL-producing adenomas, when compared with non-functional adenomas. In contrast, no upregulation of IL-18R mRNA was observed in any of the pituitary adenomas. CONCLUSIONS: The mRNA levels of IL-18, IL-18BP and IL-18R are significantly elevated in clinical pituitary tumors, such as ACTH-, GH- and PRL-producing adenomas, when compared to non-functional adenomas. These present results suggest the possibility that IL-18 may be involved in the pathogenesis of pituitary adenoma.

scholarly journals Role of KCNAB2 expression in modulating hormone secretion in somatotroph pituitary adenoma

2020 ◽  
pp. 1-7
Author(s):  
Charles Ashton ◽  
Suhn K. Rhie ◽  
John D. Carmichael ◽  
Gabriel Zada
Keyword(s):  
Pituitary Adenoma ◽  
Potassium Channel ◽  
Cell Line ◽  
Quantitative Polymerase Chain Reaction ◽  
Hormone Secretion ◽  
Gh3 Cells ◽  
Enzyme Linked Immunosorbent Assay ◽  
Human Pituitary ◽  
Voltage Gated ◽  
Gh Secretion

OBJECTIVEPrior profiling of the human pituitary adenoma (PA) DNA methylome showed the potassium channel subunit–encoding gene KCNAB2 to be highly differentially methylated between nonfunctional PAs (NFPAs) and growth hormone (GH)–secreting PAs, with greater KCNAB2 methylation detected in secretory PAs. KCNAB2 encodes an aldo-keto reductase that, among other things, negatively regulates members of the voltage-gated potassium channel (Kv) family. In this study, the authors aimed to determine whether modulation of Kcnab2 expression would alter GH secretion in the GH3 mammosomatotroph rat cell line. In addition, they examined whether dosing GH3 cells with the antiarrhythmic drug quinidine, a known inhibitor of Kv and voltage-gated sodium channels, would affect hormonal secretion.METHODSPreviously generated RNA-seq data were reanalyzed to compare KCNAB2 expression levels in human NFPAs and GH-secreting PAs. Kcnab2 was overexpressed in GH3 cells using plasmid transfection and knocked down using shRNA, with confirmation by quantitative polymerase chain reaction (qPCR). GH concentrations in cell culture supernatants collected 24 hours after cell seeding were measured using enzyme-linked immunosorbent assay (ELISA). Separately, quinidine was administered to GH3 cells at graduated doses. GH and prolactin concentrations in supernatants collected 48 hours after quinidine treatment were measured by fluorometric immunoassay.RESULTSModulation of expression at the transcript level in GH3 cells resulted in proportionate changes in the expression of GH mRNA and secretion of GH peptide, as confirmed by qPCR and ELISA. Specifically, partial knockdown of Kcnab2 was associated with fewer GH RNA transcripts and less GH secretion compared with controls, while augmentation of Kcnab2 expression was associated with more GH transcripts and secretion than the controls. Administration of quinidine (≥ 50 µM) reduced both GH and prolactin secretion in a dose-dependent fashion (p ≤ 0.05).CONCLUSIONSGH secretion in a somatotroph cell line is partially dependent on KCNAB2 gene expression and may be mitigated in vitro by quinidine. These results collectively suggest a potential new target and pharmacological candidate to be considered in the development of clinical therapeutics for acromegaly.

Human growth hormone-secreting pituitary adenoma cells in long-term culture: effects of dexamethasone and growth hormone releasing factor

1984 ◽  
Vol 100 (3) ◽  
pp. 353-360 ◽  
Author(s):  
R. Oosterom ◽  
T. Verleun ◽  
S. W. J. Lamberts
Keyword(s):  
Growth Hormone ◽  
Pituitary Adenoma ◽  
Human Growth ◽  
Prostaglandin E ◽  
Human Pituitary ◽  
Human Pituitary Adenoma ◽  
Thyrotrophin Releasing Hormone ◽  
Long Term Culture ◽  
Gh Secretion

ABSTRACT Growth hormone-secreting human pituitary adenoma cells in long-term culture show a decline in GH secretion. We investigated the effects of dexamethasone on GH production and on the responsiveness of the adenoma cells to various drugs. Twenty-four-hour GH secretion by cultures from seven acromegalics was consistently stimulated by 100 nM-dexamethasone. In four out of seven cultures the effect of dexamethasone occurred within 24 h. After 3 weeks in culture the decline in GH secretion by control cultures was over 90%, while in dexamethasone-treated cultures this was limited to less than 50%. The effect of dexamethasone was dose-dependent over a range of 1 nmol/l to 10 μmol/l. Dexamethasone stimulated not only GH secretion (fivefold), but also GH content (twofold). Cycloheximide and actinomycin D blocked the stimulatory effect of dexamethasone on GH secretion, the latter irreversibly. After 4 days of treatment with 100 nm-dexamethasone, the relative effects of somatostatin, prostaglandin E1, bromocriptine and thyrotrophin releasing hormone were the same in treated and untreated cultures. However, the response to synthetic GH releasing factor (GRF) was greatly enhanced by pretreatment of adenoma cells with dexamethasone (100 and 5 nmol/l). Cells unresponsive to small concentrations of GRF could be stimulated effectively by GRF after pretreatment with dexamethasone. In conclusion, dexamethasone prevents the decline in GH production as seen in control cultures, possibly by stimulation of DNA transcription. Furthermore, the response to GRF is greatly enhanced in the presence of dexamethasone, while the relative effects of other direct GH stimulatory and inhibitory compounds seem to be unchanged. J. Endocr. (1984) 100, 353–360

The EFEMP1 Gene: A Frequent Target for Epigenetic Silencing in Multiple Human Pituitary Adenoma Subtypes

2013 ◽  
Vol 98 (3) ◽  
pp. 200-211 ◽  
Author(s):  
Cuong V. Duong ◽  
Kiren Yacqub-Usman ◽  
Richard D. Emes ◽  
Richard N. Clayton ◽  
William E. Farrell
Keyword(s):  
Pituitary Adenoma ◽  
Epigenetic Silencing ◽  
Human Pituitary ◽  
Human Pituitary Adenoma
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