Swollen limbs and bone pain : a case report

A 50 year old man presented with peripheral oedema, abdominal distension and a pulmonary opacity on CXR. He subsequently perforated his sigmoid colon as a complication of diverticulitis with pericolic abscess. After colectomy his postoperative period was marked by severe hypokalaemia, metabolic alkalosis, hyperglycaemia and recurrent chest infections. Paraneoplastic Cushing's syndrome was diagnosed after finding elevated serum cortisol and ACTH levels. CT-guided biopsy of the lung lesion revealed small-cell carcinoma. Bone scan disclosed collapse of numerous thoracic vertebrae possibly due to osteoporosis or oncogenic osteomalacia. Treatment with steroid-synthesis blockers was commenced but the patient died before tumour-directed therapy could be started. Ectopic ACTH syndrome and oncogenic osteomalacia are discussed.peer-reviewe

Somatostatin receptor scintigraphy: Its value in tumor localization in patients with Cushing's syndrome caused by ectopic corticotropin or corticotropin-releasing hormone secretion

purpose: To assess the feasibility of somatostatin receptor scintigraphy for patients with Cushing's syndrome caused by tumors secreting ectopic corticotropin or corticotropin-releasing hormone (CRH). patients and methods: Ten patients with Cushing's syndrome, nine with ectopic corticotropin-secreting tumors and one with a CRH-secreting tumor, were consecutively studied. For comparison purposes, eight patients with corticotropin-secreting pituitary tumors and one patient with an autonomous adrenal adenoma were investigated. In vivo tumor localization was performed for all patients using a radionuclide-coupled somatostatin analog. The results obtained with this technique were compared with those obtained with conventional imaging techniques. For some patients, the clinical effects of octreotide therapy were evaluated. results: Somatostatin analog scintigraphy successfully identified the primary ectopic corticotropin-secreting and CRH-secreting tumors or their metastases, or both, in 8 of 10 patients; in 2 patients with corticotropin-secreting bronchial carcinoids, the tumors could not be visualized. Normal scans were obtained for the 8 patients with corticotropin-secreting pituitary tumors and the one patient with an adrenal adenoma. conclusion: Somatostatin analog scintigraphy can be included as a diagnostic step in the workup of Cushing's syndrome patients with a suspected ectopic corticotropin-secreting tumor or a CRH-secreting tumor

Biochemical characterization of proopiomelanocortin variants in human and owls

In humans the proopiomelanocortin (POMC) gene is located on the short arm of the chromosome 2 at the 23.3 position and encodes a 39kDa peptide with 241 amino acids. This peptide is the precursor of the proopiomelanocortin prohormone and it is produced in both the anterior and posterior lobes of the pituitary, as well as the arcuate nucleus of the hypothalamus. Maturation of POMC involves glycosylation, acetylation, and selective, sequential and tissue specific processing events mediated by proprotein convertases PC-1/3 and PC-2. Proteolytic cleavage of POMC at 9 different locations produces a variety of hormones, including adrenocorticotrophin (ACTH), α-, β- and γ-melanocyte-stimulating hormones (α-MSH, β-MSH, γ-MSH), corticotrophin-like intermediate peptide (CLIP), β-lipotropin (β-LPH), and β-endorphin (Fig. 1.)

ACTH Antagonists.

Adrenocorticotropin (ACTH) acts via a highly selective receptor that is a member of the melanocortin receptor subfamily of type 1 G protein-coupled receptors. The ACTH receptor, also known as the melanocortin 2 receptor (MC2R), is unusual in that it is absolutely dependent on a small accessory protein, melanocortin receptor accessory protein (MRAP) for cell surface expression and function. ACTH is the only known naturally occurring agonist for this receptor. This lack of redundancy and high degree of ligand specificity suggests that antagonism of this receptor could provide a useful therapeutic aid and a potential investigational tool. Clinical situations in which this could be useful include (1) Cushing's disease and ectopic ACTH syndrome - especially while preparing for definitive treatment of a causative tumor, or in refractory cases, or (2) congenital adrenal hyperplasia - as an adjunct to glucocorticoid replacement. A case for antagonism in other clinical situations in which there is ACTH excess can also be made. In this article, we will explore the scientific and clinical case for an ACTH antagonist, and will review the evidence for existing and recently described peptides and modified peptides in this role

Functional Implications of LH/hCG Receptors in Pregnancy-Induced Cushing Syndrome

Context: Elevated human choriogonadotropin (hCG) may stimulate aberrantly expressed luteinizing hormone (LH)/hCG receptor (LHCGR) in adrenal glands, resulting in pregnancy-induced bilateral macronodular adrenal hyperplasia and transient Cushing syndrome (CS). Objective: To determine the role of LHCGR in transient, pregnancy-induced CS. Design, Setting, Patient, and Intervention: We investigated the functional implications of LHCGRs in a patient presenting, at a tertiary referral center, with repeated pregnancy-induced CS with bilateral adrenal hyperplasia, resolving after parturition. Main Outcome Measures and Results: Acute testing for aberrant hormone receptors was negative except for arginine vasopressin (AVP)–increased cortisol secretion. Long-term hCG stimulation induced hypercortisolism, which was unsuppressed by dexamethasone. Postadrenalectomy histopathology demonstrated steroidogenically active adrenocortical hyperplasia and ectopic cortical cell clusters in the medulla. Quantitative polymerase chain reaction showed upregulated expression of LHCGR, transcription factors GATA4, ZFPM2, and proopiomelanocortin (POMC), AVP receptors (AVPRs) AVPR1A and AVPR2, and downregulated melanocortin 2 receptor (MC2R) vs control adrenals. LHCGR was localized in subcapsular, zona glomerulosa, and hyperplastic cells. Single adrenocorticotropic hormone–positive medullary cells were demonstrated in the zona reticularis. The role of adrenal adrenocorticotropic hormone was considered negligible due to downregulated MC2R. Coexpression of CYP11B1/CYP11B2 and AVPR1A/AVPR2 was observed in ectopic cortical cells in the medulla. hCG stimulation of the patient’s adrenal cell cultures significantly increased cyclic adenosine monophosphate, corticosterone, 11-deoxycortisol, cortisol, and androstenedione production. CTNNB1, PRKAR1A, ARMC5, and PRKACA gene mutational analyses were negative. Conclusion: Nongenetic, transient, somatic mutation-independent, pregnancy-induced CS was due to hCG-stimulated transformation of LHCGR- positive undifferentiated subcapsular cells (presumably adrenocortical progenitors) into LHCGR-positive hyperplastic cortical cells. These cells respond to hCG stimulation with cortisol secretion. Without the ligand, they persist with aberrant LHCGR expression and the ability to respond to the same stimulus

Clonal Composition of Human Adrenocortical Neoplasms

The mechanisms of tumorigenesis of adrenocortical neoplasms are still not understood. Tumor formation may be the result of spontaneous transformation of adrenocortical cells by somatic mutations. Another factor stimulating adrenocortical cell growth and potentially associated with formation of adrenal adenomas and, less frequently, carcinomas is the chronic elevation of proopiomelanocortin-derived peptides in diseases like ACTH-dependent Cushing's syndrome and congenital adrenal hyperplasia. To further investigate the pathogenesis of adrenocortical neoplasms, we studied the clonal composition of such tumors using X-chromosome inactivation analysis of the highly polymorphic region Xcen-Xp11.4 with the hybridization probe M27ß, which maps to a variable number of tandem repeats on the X-chromsome. In addition, polymerase chain reaction amplification of a phosphoglycerokinase gene polymorphism was performed. After DNA extraction from tumorous adrenal tissue and normal leukocytes in parallel, the active X-chromosome of each sample was digested with the methylation-sensitive restriction enzyme HpaII. A second digestion with an appropriate restriction enzyme revealed the polymorphism of the region Xcen-Xp11.4 and the phosphoglycerokinase locus. Whereas in normal polyclonal tissue both the paternal and maternal alleles are detected, a monoclonal tumor shows only one of the parental alleles. A total of 21 female patients with adrenal lesions were analyzed; 17 turned out to be heterozygous for at least one of the loci. Our results were as follows: diffuse (n = 4) and nodular (n = 1) adrenal hyperplasia in patients with ACTH-dependent Cushing's syndrome, polyclonal pattern; adrenocortical adenomas (n = 8), monoclonal (n = 7), as well as polyclonal (n = 1); adrenal carcinomas (n = 3), monoclonal pattern. One metastasis of an adrenocortical carcinoma showed a pattern most likely due to tumor-associated loss of methylation. In the special case of a patient with bilateral ACTH-independent macronodular hyperplasia, diffuse hyperplastic areas and a small nodule showed a polyclonal pattern, whereas a large nodule was monoclonal. We conclude that most adrenal adenomas and carcinomas are monoclonal, whereas diffuse and nodular adrenal hyperplasias are polyclonal. The clonal composition of ACTH-independent massive macronodular hyperplasia seems to be heterogeneous, consisting of polyclonal and monoclonal areas

POMC: The Physiological Power of Hormone Processing.

Pro-opiomelanocortin (POMC) is the archetypal polypeptide precursor of hormones and neuropeptides. In this review, we examine the variability in the individual peptides produced in different tissues and the impact of the simultaneous presence of their precursors or fragments. We also discuss the problems inherent in accurately measuring which of the precursors and their derived peptides are present in biological samples. We address how not being able to measure all the combinations of precursors and fragments quantitatively has affected our understanding of the pathophysiology associated with POMC processing. To understand how different ratios of peptides arise, we describe the role of the pro-hormone convertases (PCs) and their tissue specificities and consider the cellular processing pathways which enable regulated secretion of different peptides that play crucial roles in integrating a range of vital physiological functions. In the pituitary, correct processing of POMC peptides is essential to maintain the hypothalamic-pituitary-adrenal axis, and this processing can be disrupted in POMC-expressing tumors. In hypothalamic neurons expressing POMC, abnormalities in processing critically impact on the regulation of appetite, energy homeostasis, and body composition. More work is needed to understand whether expression of the POMC gene in a tissue equates to release of bioactive peptides. We suggest that this comprehensive view of POMC processing, with a focus on gaining a better understanding of the combination of peptides produced and their relative bioactivity, is a necessity for all involved in studying this fascinating physiological regulatory phenomenon

Somatostatin and dopamine receptors as targets for medical treatment of Cushing's Syndrome

Somatostatin (SS) and dopamine (DA) receptors are widely expressed in neuroendocrine tumours that cause Cushing's Syndrome (CS). Increasing knowledge of specific subtype expression within these tumours and the ability to target these receptor subtypes with high-affinity compounds, has driven the search for new SS- or DA-based medical therapies for the various forms of CS. In Cushing's disease, corticotroph adenomas mainly express dopamine receptor subtype 2 (D2) and somatostatin receptor subtype 5 (sst5), whereas sst2is expressed at lower levels. Activation of these receptors can inhibit ACTH-release in primary cultured corticotroph adenomas and compounds that target either sst5(pasireotide, or SOM230) or D2(cabergoline) have shown significant efficacy in subsets of patients in recent clinical studies. Combination therapy, either by administration of both types of compounds separately or by treatment with novel somatostatin-dopamine chimeric molecules (e.g. BIM-23A760), appears to be a promising approach in this respect. In selected cases of Ectopic ACTH-producing Syndrome (EAS), the sst2-preferring compound octreotide is able to reduce cortisol levels effectively. A recent study showed that D2receptors are also significantly expressed in the majority of EAS and that cabergoline may decrease cortisol levels in subsets of these patients. In both normal adrenal tissue as well as in adrenal adenomas and carcinomas that cause CS, sst and DA receptor expression has been demonstrated. Although selected cases of adrenal CS may benefit from sst or DA-targeted treatment, its total contribution to the treatment of these patients is likely to be low as surgery is effective in most cases