The Cables1 Gene in Glucocorticoid Regulation of Pituitary Corticotrope Growth and Cushing Disease

Posted on March 14, 2017 by MaryO

Audrey Roussel-Gervais 1 Catherine Couture 1 David Langlais 1 Shinobu Takayasu 1 Aurelio Balsalobre 1 Bo R. Rueda 2 Lawrence R. Zukerberg 2 Dominique Figarella-Branger 3, 4 Thierry Brue 5 Jacques Drouin 2

Details

1 Laboratoire de Génétique Moléculaire
2 MGH – Massachusetts General Hospital [Boston]
3 LA CONCEPTION – Hôpital de la Conception [CHU – APHM]
4 ACPNP – Service d’Anatomo-Cyto-Pathologie et de NeuroPathologie [Hôpital de la Timone – APHM]
5 CRN2M – Centre de recherche en neurobiologie – neurophysiologie de Marseille
Abstract :
Context: Cushing disease (CD) is due to pituitary corticotrope adenomas that produce unrestrained ACTH secretion and have lost the negative feedback exerted by glucocorticoids (GCs). GCs also restrain corticotrope proliferation, and the mechanisms of this inhibition are poorly understood.
Objective: The aim of the study was to identify cell cycle regulatory genes that are regulated by GCs and the glucocorticoid receptor and to assess regulatory genes that have a rate-limiting action on corticotrope proliferation and may be disregulated in CD.
Design: The mouse corticotrope tumor cells AtT-20 were used to identify GC-regulated genes that contribute to control of cell cycle progression. Surgery sections from patients with CD were used to assess expression of CABLES1 in corticotrope adenomas.
Methods: Gene expression profiling, small interfering RNA knockdowns, cell cycle analyses, and genetic manipulations were performed in AtT-20 cells. Sequencing of chromatin immunoprecipitation for pituitary-restricted transcription factors and RNA polymerase II were used to identify regulatory elements and genes that bind GR and are direct transcriptional targets. A panel of previously well-characterized corticotrope adenomas was used to correlate expression of CABLES1 with that of other markers. Results: GCs altered expression of 3 positive and 3 negative regulators of cell cycle progression. Two Myc genes (L-Myc and N-Myc) and E2F2 are repressed by GCs, whereas genes for the negative regulators of the cell cycle, Gadd45, Gadd45, and Cables1 are activated by GCs. Cables1 small interfering RNA knockdown strongly stimulates AtT-20 cell proliferation and antagonizes the growth inhibition produced by GCs. The Gadd45 and Cables1 genes have the hallmarks of direct GC targets. CABLES1 is expressed in normal human pituitary cells, but expression is lost in 55% of corticotrope adenomas, and this is strongly correlated with the loss of p27 Kip1 expression.
Conclusions: CABLES1 is a critical regulator of corticotrope proliferation that defines a pathway often inactivated in CD and links proliferation to GC resistance. (J Clin Endocrinol Metab

Document type :

Journal articles
Journal of Clinical Endocrinology and Metabolism, Endocrine Society, 2016, 101 (2), pp.513-522. <10.1210/jc.2015-3324>

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Diagnosis and Treatment of Pituitary Adenomas

Posted on February 8, 2017 by MaryO
A Review
Mark E. Molitch, MD1
Author Affiliations
JAMA. 2017;317(5):516-524. doi:10.1001/jama.2016.19699

Importance  Pituitary adenomas may hypersecrete hormones or cause mass effects. Therefore, early diagnosis and treatment are important.

Observations  Prevalence of pituitary adenomas ranges from 1 in 865 adults to 1 in 2688 adults. Approximately 50% are microadenomas (<10 mm); the remainder are macroadenomas (≥10 mm).

Mass effects cause headache, hypopituitarism, and visual field defects. Treatments include transsphenoidal surgery, medical therapies, and radiotherapy. Prolactinomas account for 32% to 66% of adenomas and present with amenorrhea, loss of libido, galactorrhea, and infertility in women and loss of libido, erectile dysfunction, and infertility in men; they are generally treated with the dopamine agonists cabergoline and bromocriptine.

Growth hormone–secreting tumors account for 8% to 16% of tumors and usually present with enlargement of the lips, tongue, nose, hands, and feet and are diagnosed by elevated insulin-like growth factor 1 levels and growth hormone levels; initial treatment is surgical. Medical therapy with somatostatin analogues, cabergoline, and pegvisomant is often also needed.

Adrenocorticotropic hormone (ACTH)–secreting tumors account for 2% to 6% of adenomas and are associated with obesity, hypertension, diabetes, and other morbidity. Measurement of a late-night salivary cortisol level is the best screening test but petrosal sinus sampling for ACTH may be necessary to distinguish a pituitary from an ectopic source.

The primary treatment of Cushing disease (hypercortisolism due to ACTH-producing adenomas, which is the cause in approximately 65% of the cases of hypercortisolism) is adenoma resection and medical therapies including ketoconazole, mifepristone, and pasireotide.

Hyperthyroidism due to thyroid-stimulating hormone–secreting tumors accounts for 1% of tumors and is treated with surgery and somatostatin analogues if not surgically cured. Clinically nonfunctioning adenomas account for 15% to 54% of adenomas and present with mass effects; surgery is generally required, although incidentally found tumors can be followed if they are asymptomatic.

Conclusions and Relevance  Patients with pituitary adenomas should be identified at an early stage so that effective treatment can be implemented. For prolactinomas, initial therapy is generally dopamine agonists. For all other pituitary adenomas, initial therapy is generally transsphenoidal surgery with medical therapy being reserved for those not cured by surgery.

Read the full text here: http://jamanetwork.com/journals/jama/article-abstract/2600472

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Bilateral testicular tumors resulting in recurrent Cushing’s syndrome after bilateral adrenalectomy

Posted on December 21, 2016 by MaryO
Troy Puar1,2, Manon Engels3,4, Antonius E. van Herwaarden4, Fred C. G. J. Sweep4, Christina Hulsbergen-van de Kaa5, Karin Kamphuis-van Ulzen6, Vasileios Chortis7,8, Wiebke Arlt7,8, Nike Stikkelbroeck1, Hedi L Claahsen–van der Grinten3, Ad R.M.M. Hermus1
Corresponding author: Troy Puar, MRCP (UK), Department of Medicine, Div. of Endocrinology, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands. Phone: +31 243614599, Fax: +31 243618809, e-mail: Troy_puar@cgh.com.sg
DOI: http://dx.doi.org/10.1210/jc.2016-2702
Received: July 14, 2016
Accepted: November 29, 2016
First Published Online: November 30, 2016
Abstract
Context:

Recurrence of hypercortisolism in patients after bilateral adrenalectomy for Cushing’s disease is extremely rare.

Patient:

We present a rare case of a 27-year-old man who previously underwent bilateral adrenalectomy for Cushing’s disease with complete clinical resolution. Cushingoid features recurred 12 years later, along with bilateral testicular enlargement. Hormonal tests confirmed ACTH-dependent Cushing’s. Surgical resection of the testicular tumors led to clinical and biochemical remission.

Design and Results:
Gene expression analysis of the tumor tissue by qPCR showed high expression of all key steroidogenic enzymes. Adrenocortical-specific genes were 5.1 x 105 (CYP11B1), 1.8 x 102 (CYP11B2) and 6.3 x 104 (MC2R) times higher than non-steroidogenic fibroblast control. This correlated with urine steroid metabolome profiling showing 2-5 fold increases in the excretion of the metabolites of 11-deoxycortisol, 21-deoxycortisol and total glucocorticoids. Leydig-specific genes were 4.3 x 101 (LHCGR) and 9.3 x 100(HSD17B3) times higher than control and urinary steroid profiling showed 2-fold increased excretion of the major androgen metabolites androsterone and etiocholanolone. These distinctly increased steroid metabolites were suppressed by dexamethasone, but unresponsive to hCG stimulation, supporting the role of ACTH, but not LH, in regulating tumor-specific steroid excess.
Conclusion:

We report bilateral testicular tumors occurring in a patient with recurrent Cushing’s disease 12 years after bilateral adrenalectomy. Using mRNA expression analysis and steroid metabolome profiling, the tumors demonstrated both adrenocortical and gonadal steroidogenic properties, similar to testicular adrenal rest tumors found in patients with congenital adrenal hyperplasia. This suggests the presence of pluripotent cells even in patients without CAH.

Affiliations
  • 1Department of Medicine, Division of Endocrinology, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands.
  • 2Department of Endocrinology, Changi General Hospital, Singapore 529889, Singapore.
  • 3Department of Paediatrics, Division of Endocrinology, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands.
  • 4Department of Laboratory Medicine, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands.
  • 5Department of Pathology, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands.
  • 6Department of Radiology, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands.
  • 7Institute of Metabolism and Systems Research, University of Birmingham, Birmingham N15 2TT, United Kingdom.
  • 8Centre for Endocrinology, Diabetes, and Metabolism, Birmingham Health Partners, Birmingham B15 2TH, United Kingdom.

– See more at: http://press.endocrine.org/doi/abs/10.1210/jc.2016-2702#sthash.F4lfWg9j.dpuf

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Cushing’s Syndrome mutant PKAL205R exhibits altered substrate specificity

Posted on December 15, 2016 by MaryO

Joshua M Lubner, Kimberly L Dodge-Kafka, Cathrine R Carlson, George M Church, Michael F Chou, Daniel Schwartz
doi: https://doi.org/10.1101/091231
This article is a preprint and has not been peer-reviewed.

 

Abstract

The PKAL205R hotspot mutation has been implicated in Cushing’s Syndrome through hyperactive gain-of-function PKA signaling, however its influence on substrate specificity has not been investigated.

Here, we employ the Proteomic Peptide Library (ProPeL) approach to create high-resolution models for PKAWT and PKAL205R substrate specificity. We reveal that the L205R mutation reduces canonical hydrophobic preference at the substrate P+1 position, and increases acidic preference in downstream positions. Using these models, we designed peptide substrates that exhibit altered selectivity for specific PKA variants, and demonstrate the feasibility of selective PKAL205R loss-of-function signaling.

Through these results, we suggest that substrate rewiring may contribute to Cushing’s Syndrome disease etiology, and introduce a powerful new paradigm for investigating mutation-induced kinase substrate rewiring in human disease.

Full PDF at http://biorxiv.org/content/early/2016/12/05/091231.full.pdf+html

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Medical Therapies in Cushing’s Syndrome

Posted on December 4, 2016 by MaryO
Chapter

The Hypothalamic-Pituitary-Adrenal Axis in Health and Disease

pp 165-179

Date: 03 December 2016

Medical Therapies in Cushing’s Syndrome

Abstract

Medical therapy has an important, albeit secondary, role in patients with Cushing’s syndrome. While medications are not currently used as definitive therapy of this condition, they can be very effective in controlling hypercortisolism in patients who fail surgery, those who are not surgical candidates, or those whose tumor location is unknown. Medical therapies can be particularly helpful to control hypercortisolism in patients with Cushing’s disease who underwent radiation therapy and are awaiting its salutary effects.

Currently available treatment options include several steroidogenesis inhibitors (ketoconazole, metyrapone, mitotane, etomidate), which block one or several steps in cortisol synthesis in the adrenal glands, centrally acting agents (cabergoline, pasireotide), which decrease ACTH secretion, and glucocorticoid receptor antagonists, which are represented by a single agent (mifepristone). With the exception of pasireotide and mifepristone, available agents are used “off-label” to manage hypercortisolism. Several other medications are at various stages of development and may offer additional options for the management of this serious condition.

As more potential molecular targets become known and our understanding of the pathogenesis of Cushing’s syndrome improves, it is anticipated that novel, rationally designed medical therapies may emerge. Clinical trials are needed to further investigate the relative risks and benefits of currently available and novel medical therapies and examine the potential role of combination therapy in the management of Cushing’s syndrome.

Keywords

Cabergoline, Etomidate, Ketoconazole, Levoketoconazole, Metyrapone, Mifepristone, Mitotane, Osilodrostat, Pasireotide, Pituitary adenoma

From http://link.springer.com/chapter/10.1007/978-3-319-45950-9_9

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