ANNIVERSARY REVIEW: Octreotide, 40 years later

Octreotide remains 40 years after its development a drug, which is commonly used in the treatment of acromegaly and GEP-NETs. Very little innovation that competes with this drug occurred over this period. This review discusses several aspects of 40 years of clinical use of octreotide, including the application of radiolabeled forms of the peptide.

The physiology of endocrine systems with ageing

During ageing, the secretory patterns of the hormones produced by the hypothalamic-pituitary axis change, as does the sensitivity of the axis to negative feedback by end hormones. Additionally, glucose homoeostasis tends towards disequilibrium with increasing age. Along with these endocrine alterations, a loss of bone and muscle mass and strength occurs, coupled with an increase in fat mass. In addition, ageing-induced effects are difficult to disentangle from the influence of other factors that are common in older people, such as chronic diseases, inflammation, and low nutritional status, all of which can also affect endocrine systems. Traditionally, the decrease in hormone activity during the ageing process has been considered to be detrimental because of the related decline in bodily functions. The concept of hormone replacement therapy was suggested as a therapeutic intervention to stop or reverse this decline. However, clearly some of these changes are a beneficial adaptation to ageing, whereas hormonal intervention often causes important adverse effects. In this paper, we discuss the effects of age on the different hypothalamic-pituitary-hormonal organ axes, as well as age-related changes in calcium and bone metabolism and glucose homoeostasis.

Dopamine D2 receptor expression in the corticotroph cells of the human normal pituitary gland

The dopamine D₂ receptor is the main dopamine receptor expressed in the human normal pituitary gland. The aim of the current study was to evaluate dopamine D₂ receptor expression in the corticotroph cell populations of the anterior lobe and pars intermedia, as well as posterior lobe of the human normal pituitary gland by immunohistochemistry. Human normal pituitary gland samples obtained from routine autopsies were used for the study. In all cases, histology together with immunostaining for adrenocorticotropic hormone, melanocyte-stimulating hormone, prolactin, and neurofilaments were performed and compared to the immunostaining for D₂ receptor. D₂ receptor was heterogeneously expressed in the majority of the cell populations of the anterior and posterior lobe as well as in the area localized between the anterior and posterior lobe, and arbitrary defined as "intermediate zone". This zone, characterized by the presence of nerve fibers included the residual pars intermedia represented by the colloid-filled cysts lined by the remnant melanotroph cells strongly expressing D₂ receptors, and clusters of corticotroph cells, belonging to the anterior lobe but localized within the cysts and adjacent to the posterior lobe, variably expressing D₂ receptors. D₂ dopamine receptor is expressed in the majority of the cell populations of the human normal pituitary gland, and particularly, in the different corticotroph cell populations localized in the anterior lobe and the intermediate zone of the pituitary gland.

In Vitro Head-to-Head Comparison Between Octreotide and Pasireotide in GH-Secreting Pituitary Adenomas

CONTEXT

First-generation somatostatin analogs (SSAs), such as octreotide (OCT), are the first line medical therapy for acromegaly. Pasireotide (PAS), a newly developed SSA, has shown promising results in the treatment of acromegaly.

OBJECTIVE

To compare the antisecretory effect of OCT and PAS in primary cultures of growth hormone (GH)-secreting pituitary adenomas (GH-omas). To correlate responses with the adenoma somatostatin receptor (SSTR) profile.

DESIGN

The effect of OCT and PAS on GH (and PRL) secretion was tested in 33 GH-oma cultures. SSTR expression was evaluated in adenoma samples.

SETTING AND PATIENTS

Patients with acromegaly referred to the Erasmus Medical Center (Rotterdam, The Netherlands).

INTERVENTIONS

OCT and PAS treatment for 72 hours (10 nM).

MAIN OUTCOME MEASURES

GH (and PRL) concentrations in cell culture media. SSTR expression in adenoma samples.

RESULTS

The overall effect of OCT (-36.8%) and PAS (-37.1%) on GH secretion was superimposable. We identified three adenoma groups: PAS+ (PAS more effective than OCT), n = 6; PAS = OCT, n = 22; and OCT+ (OCT more effective than PAS), n = 5. PAS+ adenomas showed lower somatostatin receptor subtype (sst)2 messenger RNA (mRNA) and sst2/sst5 mRNA ratio, compared with the other groups (P < 0.05). PAS inhibited PRL hypersecretion more than OCT (P < 0.01).

CONCLUSIONS

Overall, OCT and PAS equally reduced GH secretion in vitro. Adenomas with lower sst2 mRNA expression and lower sst2/sst5 mRNA ratio were better responders to PAS compared with OCT. SSTR evaluation in GH-omas may become a tool for tailored SSA treatment in acromegaly.

Somatostatin analogues in acromegaly and gastroenteropancreatic neuroendocrine tumours: past, present and future

Acromegaly is a hormonal disorder that arises when the pituitary gland secretes excess growth hormone (GH), which in turn stimulates a concomitant increase in serum insulin-like growth factor 1 (IGF-1) levels. Gastroenteropancreatic neuroendocrine tumours (GEP-NET) constitute a heterogeneous group of tumours that can secrete serotonin and a variety of peptide hormones that may cause characteristic symptoms known as carcinoid syndrome or other symptoms and hormonal hypersecretion syndromes depending on the tumour's site of origin. Current medical therapy for the treatment of acromegaly and GEP-NET involves the administration of somatostatin analogues that effectively suppress excess hormone secretion. After its discovery in 1979, octreotide became the first synthetic biologically stable somatostatin analogue with a short-acting formulation of octreotide introduced into clinical practice in the late 1980s. Lanreotide, another somatostatin analogue, became available in the mid-1990s initially as a prolonged-release formulation administered every 10 or 14 days. Long-acting release formulations of both octreotide (Sandostatin LAR and Novartis) and lanreotide (Somatuline Autogel, Ipsen), based on microparticle and nanoparticle drug-delivery technologies, respectively, were later developed, which allowed for once-monthly administration and improved convenience. First-generation somatostatin analogues remain one of the cornerstones of medical therapy in the management of pituitary and GEP-NET hormone hypersecretion, with octreotide having the longest established efficacy and safety profile of the somatostatin analogue class. More recently, pasireotide (Signifor), a next-generation multireceptor-targeted somatostatin analogue, has emerged as an alternative therapeutic option for the treatment of acromegaly. This review summarizes the development and clinical success of somatostatin analogues.

Epidrug-induced upregulation of functional somatostatin type 2 receptors in human pancreatic neuroendocrine tumor cells

Somatostatin receptors are a pivotal target for treatment of pancreatic neuroendocrine tumors (pNET), either with somatostatin analogues (SSA) or radiolabeled SSA. The highest affinity target for the most commonly used SSA is the somatostatin receptor type 2 (sst₂ ). An important factor that may complicate treatment efficacy, is the variable number of receptors expressed on pNETs. Gene expression is subject to complex regulation, in which epigenetics has a central role. In this study we explored the possible role of epigenetic modifications in the variations in sst₂ expression levels in two human pNET cell lines, BON-1 and QGP-1. We found upregulation of sst₂ mRNA after treatment with the epidrugs 5-aza-2'-deoxycytidine (5-aza-dC) and valproic acid (VPA), an increased uptake of radiolabeled octreotide, as well as increased sensitivity to the SSA octreotide in functional cAMP inhibition. At epigenetic level we observed low methylation levels of the sst₂ gene promoter region irrespective of expression. Activating histone mark H3K9Ac can be regulated with epidrug treatment, with an angle of effect corresponding to the effect on mRNA expression. Repressive histone mark H3K27me3 is not regulated by either 5-aza-dC or VPA. We conclude that epidrug treatment, in particular with combined 5-aza-dC and VPA treatment, might hold promise for improving and adding to current SSA treatment strategies of patients with pNETs.

Low beta-arrestin expression correlates with the responsiveness to long-term somatostatin analog treatment in acromegaly

OBJECTIVE

The high expression of somatostatin receptor subtype 2 (SSTR2 also known as sst2) usually present in growth hormone (GH)-secreting adenomas is the rationale for therapy with somatostatin analogs (SSAs) in acromegaly. Although SSTR2 expression is a good predictor for biochemical response to SSA treatment, we still face tumors resistant to SSAs despite high SSTR2 expression. Recently, beta-arrestins (β-arrestins) have been highlighted as key players in the regulation of SSTR2 function.

DESIGN

To investigate whether β-arrestins might be useful predictors of responsiveness to long-term SSA treatment in acromegaly, we retrospectively evaluated 35 patients with acromegaly who underwent adenomectomy in two referral centers in The Netherlands.

METHODS

β-arrestin mRNA levels were evaluated in adenoma samples, together with SSTR2 (and SSTR5) mRNA and protein expression. Biochemical response to long-term SSA treatment (median 12 months) was assessed in 32 patients.

RESULTS

β-arrestin 1 and 2 mRNA was significantly lower in adenoma tissues from patients who achieved insulin-like growth factor 1 normalization (P = 0.024 and P = 0.047) and complete biochemical control (P = 0.047 and P = 0.039). The SSTR2 mRNA was higher in SSA responder patients compared with the resistant ones (P = 0.026). This difference was more evident when analyzing the SSTR2/β-arrestin 1 and SSTR2/β-arrestin 2 ratio (P = 0.011 and P = 0.010). β-arrestin 1 and 2 expression showed a significant trend of higher median values from full responders, partial responders to resistant patients (P = 0.045 and P = 0.021, respectively). Interestingly, SSTR2 protein expression showed a strong inverse correlation with both β-arrestin 1 and 2 mRNA (ρ = -0.69, P = 0.0011 and ρ = -0.67, P = 0.0016).

CONCLUSIONS

Low β-arrestin expression and high SSTR2/β-arrestin ratio correlate with the responsiveness to long-term treatment with SSAs in patients with acromegaly.

[From annual check-up to annual appraisal: personalised diabetes care]

Diabetes care is shifting from disease management to personalised care. Internationally, diabetes care providers are advised to integrate the patient's preferences, wishes and possibilities into diabetes care in order to improve its efficiency. The Dutch Diabetes Federation has developed a specifically patient-centred conversation model that can be systematically applied. At an annual appraisal, the physician and the patient make decisions on the treatment goals to set, and on the treatment and professional support needed to achieve these goals. In this way person-centred and efficient care may become reality. The first results of a pilot study are promising. Currently the applicability and added value of the model are being tested on a large scale. The model is more broadly applicable, which means this could be a new perspective for everyone with a chronic disease.

Effects of Somatostatin Analogs and Dopamine Agonists on Insulin-Like Growth Factor 2-Induced Insulin Receptor Isoform A Activation by Gastroenteropancreatic Neuroendocrine Tumor Cells

BACKGROUND

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) express insulin-like growth factor (IGF)-related factors [IGF1, IGF2; insulin receptor (IR)-A, IR-B; IGF-binding protein (IGFBP) 1-3] as well as somatostatin (SSTRs) and dopamine D2 receptors (D2Rs).

OBJECTIVES

To (1) compare mRNA expression of IGF-related factors in human pancreatic NET (panNET) cell lines with that in human GEP-NETs to evaluate the usefulness of these cells as a model for studying the IGF system in GEP-NETs, (2) determine whether panNET cells produce growth factors that activate IR-A, and (3) investigate whether somatostatin analogs (SSAs) and/or dopamine agonists (DAs) influence the production of these growth factors.

METHODS

In panNET cells (BON-1 and QGP-1) and GEP-NETs, mRNA expression of IGF-related factors was measured by quantitative real-time PCR. Effects of the SSAs octreotide and pasireotide (PAS), the DA cabergoline (CAB), and the dopastatin BIM-23A760 (all 100 nM) were evaluated at the IGF2 mRNA and protein level (by ELISA) and regarding IR-A bioactivity (by kinase receptor activation assay) in panNET cells.

RESULTS

panNET cells and GEP-NETs had comparable expression profiles of IGF-related factors. Especially in BON-1 cells, IGF2 and IR-A were most highly expressed. PAS + CAB inhibited IGF2 (-29.5 ± 4.9%, p < 0.01) and IGFBP3 (-20.0 ± 4.0%, p < 0.01) mRNA expression in BON-1 cells. In BON-1 cells, IGF2 protein secretion was significantly inhibited with BIM-23A760 (-23.7 ± 3.8%). BON-1- but not QGP-1- conditioned medium stimulated IR-A bioactivity. In BON-1 cells, IR-A bioactivity was inhibited by BIM-23A760 and PAS + CAB (-37.8 ± 2.1% and -30.9 ± 4.1%, respectively, p < 0.0001).

CONCLUSIONS

(1) The BON-1 cell line is a representative model for studying the IGF system in GEP-NETs, (2) BON-1 cells produce growth factors (IGF2) activating IR-A, and (3) combined SSTR and D2R targeting with PAS + CAB and BIM-23A760 suppresses IGF2-induced IR-A activation.

Changes in circulating IGF1 receptor stimulating activity do not parallel changes in total IGF1 during GH treatment of GH-deficient adults

CONTEXT

Previously we demonstrated that IGF1 receptor stimulating activity (IGF1RSA) offers advantages in diagnostic evaluation of adult GH deficiency (GHD). It is unknown whether IGF1RSA can be used to monitor GH therapy.

OBJECTIVE

To investigate the value of circulating IGF1RSA for monitoring GH therapy.

DESIGN/METHODS

106 patients (54 m; 52 f) diagnosed with GHD were included; 22 were GH-naïve, 84 were already on GH treatment and discontinued therapy 4 weeks before baseline values were established. IGF1RSA was determined by the IGF1R kinase receptor activating assay, total IGF1 by immunoassay (Immulite). GH doses were titrated to achieve total IGF1 levels within the normal range.

RESULTS

After 12 months, total IGF1 and IGF1RSA increased significantly (total IGF1 from 8.1 (95% CI 7.3-8.9) to 14.9 (95% CI 13.5-16.4) nmol/l and IGF1RSA from 115 (95% CI 104-127) to 181 (95% CI 162-202) pmol/l). After 12 months, total IGF1 normalized in 81% of patients, IGF1RSA in 51% and remained below normal in more than 40% of patients in whom total IGF1 had normalized.

CONCLUSIONS

During 12 months of GH treatment, changes in IGF1RSA did not parallel changes in total IGF1. Despite normalization of total IGF1, IGF1RSA remained subnormal in a considerable proportion of patients. At present our results have no short-term consequences for GH therapy of GHD patients. However, based on our findings we propose future studies to examine whether titrating GH dose against IGF1RSA results in a better clinical outcome than titrating against total IGF1.

Cushing's syndrome: an update on current pharmacotherapy and future directions

INTRODUCTION

Endogenous Cushing's syndrome (CS) is characterized by chronic overproduction of cortisol and is associated with increased mortality and morbidity. It can be caused by a pituitary adenoma, ectopic adrenocorticotropic hormone (ACTH) production or primary adrenal disease. Successful tumor-directed surgery is the keystone treatment. When surgery is unsuccessful, contraindicated or in case of acute disease, pharmacotherapy is indicated to treat hypercortisolism.

AREAS COVERED

In this review, pharmacotherapeutic options for CS will be covered discussing the different possible targets, that is: i) inhibition of ACTH secretion; ii) suppression of steroidogenesis; and iii) blockade of cortisol effects at tissue level. Preclinical and clinical studies will be discussed considering mono- and combination therapy, taking into account efficacy, toxicity and mechanism of action. Per CS entity, future directions of pharmacotherapies will be addressed.

EXPERT OPINION

The number of medical treatment options for CS has increased in the past years. In contrast to decades ago, prospective trials are now being performed focusing on pituitary-directed drugs like pasireotide, the glucocorticoid receptor blocker mifepristone and 'new generation' steroid synthesis inhibitors. Future studies will focus on tumor-shrinking effects of neuromodulatory drugs, the optimal order and combination of pharmacotherapy, long-term efficacy and safety and new targets for medical treatment of CS.

Polymorphisms in the glucocorticoid receptor gene and in the glucocorticoid-induced transcript 1 gene are associated with disease activity and response to glucocorticoid bridging therapy in rheumatoid arthritis

Glucocorticoids (GC) are widely used in rheumatoid arthritis (RA). Ongoing active disease due to GC resistance may unfavorably influence long-term disease outcome in RA. We studied the association between the presence of glucocorticoid receptor (GR) and glucocorticoid-induced transcript 1 (GLCCI1) gene polymorphisms, which modulate GC sensitivity, and baseline disease activity score (DAS) and efficacy of GC bridging therapy in RA. We prospectively studied in vivo GC sensitivity in 138 patients with recent-onset or longstanding RA. In vivo GC sensitivity was expressed as the relative decrease in DAS following 2 weeks of standardized GC therapy. All patients were genotyped for the GR polymorphisms BclI (rs41423247), N363S (rs6195), 9β (rs6198), ER22/23EK (rs6189 + rs6190), and the GLCCI1 variant rs37972 and subsequently divided in groups carrying a polymorphism associated with increased GC sensitivity (BclI-G allele, N363S-G allele, GLCCI1-C allele) or decreased GC sensitivity (9β-G allele, ER22/23EK-A/A allele, GLCCI1-T allele). Differences in baseline DAS and relative decrease in DAS in the different genotype groups were analyzed using analysis of covariance and linear regression. Baseline DAS was higher in patients who carried polymorphisms of the GR and GLCCI1 genes associated with decreased GC sensitivity. GLCCI1 genotype, but not GR genotypes, was associated with improvement in DAS in male patients with RA. The GLCCI1 gene minor allele (rs37972) may be associated with less efficient GC bridging therapy in male RA patients. Carriers of the BclI-G, N363S-G, or GLCCI1-C alleles had lower levels of baseline disease activity, suggesting a role for the GLCCI1 and GR gene in regulation of GC sensitivity to endogenously produced cortisol.

The introduction of the IDS-iSYS total IGF-1 assay may have far-reaching consequences for diagnosis and treatment of GH deficiency

CONTEXT

IGF-1 measurements are used for screening and monitoring GH deficiency (GHD) and acromegaly.

OBJECTIVE

Our objective was to study whether the introduction of the IDS-iSYS IGF-1 assay would lead to different clinical interpretations in GHD and acromegaly.

DESIGN

In 106 GHD subjects and in 15 acromegalic subjects visiting our university hospital, total IGF-1 levels were measured before and during therapy by using the Immulite (IM) assay and IDS-iSYS (ID) assay. Z-scores were calculated by using assay-specific age-specific normative range values. All treatment decisions were based upon results obtained by the IM assay.

RESULTS

In GHD subjects, absolute IGF-1 concentrations differed significantly between both IGF-1 assays before treatment (P < .001) but not during GH treatment (P = .32), and mean Z-scores for IGF-1 differed significantly before starting (IM, -2.23, vs ID, -1.43; P < .001) and during GH treatment (IM, -0.60, vs ID, +0.21; P < .001). In acromegalic subjects, absolute IGF-1 concentrations did not differ between both IGF-1 assays before treatment (P = .18) but were significantly different during treatment (P = 0.009), and mean Z-scores for IGF-1 were not different before starting (IM, 10.93, vs ID, 10.78; P = .41) or during treatment (IM, 3.60, vs ID, 3.18; P = .23).

CONCLUSIONS

In GHD subjects, mean IGF-1 Z-scores significantly differed when measured by the IM assay compared with the ID assay irrespective of treatment. In contrast, in acromegaly, mean IGF-1 Z-scores did not differ significantly between both assays. Our study suggests that replacement of the IM assay by the ID assay may have far-reaching consequences for the clinical diagnosis and treatment of GHD.

Characterization of the mTOR pathway in human normal adrenal and adrenocortical tumors

The mTOR pathway has recently been suggested as a new potential target for therapy in adrenocortical carcinomas (ACCs). The aim of the current study is to describe the expression of the mTOR pathway in normal adrenals (NAs) and pathological adrenals and to explore whether there are correlation between the expression of these proteins and the in vitro response to sirolimus. For this purpose, the MTOR, S6K1 (RPS6KB1), and 4EBP1 (EIF4EBP1) mRNA expression were evaluated in ten NAs, ten adrenal hyperplasias (AHs), 17 adrenocortical adenomas (ACAs), and 17 ACCs by qPCR, whereas total(t)/phospho(p)-MTOR, t/p-S6K, and t/p-4EBP1 protein expression were assessed in three NAs, three AHs, six ACAs, and 20 ACCs by immunohistochemistry. The effects of sirolimus on cell survival and/or cortisol secretion in 12 human primary cultures of adrenocortical tumors (ATs) were also evaluated. In NAs and AHs, layer-specific expression of evaluated proteins was observed. S6K1 mRNA levels were lower in ACCs compared with NAs, AHs, and ACAs (P<0.01). A subset of ATs presented a moderate to high staining of the evaluated proteins. Median t-S6K1 protein expression in ACCs was lower than that in ACAs (P<0.01). Moderate to high staining of p-S6K1 and/or p-4EBP1 was observed in most ATs. A subset of ACCs not having moderate to high staining had a higher Weiss score than others (P<0.029). In primary AT cultures, sirolimus significantly reduced cell survival or cortisol secretion only in sporadic cases. In conclusion, these data suggest the presence of an activated mTOR pathway in a subset of ATs and a possible response to sirolimus only in certain ACC cases.

Advances in the assessment of cortisol exposure and sensitivity

PURPOSE OF REVIEW

To review recent progress in the field of cortisol exposure and sensitivity, and its implications for research concerning obesity and related metabolic disturbances.

RECENT FINDINGS

In the past few years, scalp hair analysis had been successfully introduced as a marker for long-term cortisol exposure. With this relatively novel method, increased long-term cortisol levels have been linked to cardiovascular disease, metabolic syndrome, and stress-related measures. At the tissue level, the effect of cortisol is modulated by genetically determined glucocorticoid sensitivity. Polymorphisms in the glucocorticoid receptor gene that influence glucocorticoid sensitivity have been associated with differences in metabolic syndrome components.

SUMMARY

Hair analysis provides exciting new opportunities to study the influence of long-term cortisol exposure on a wide range of health outcomes, in both observational and interventional studies. We propose that addition of genetically determined glucocorticoid sensitivity to these studies may bring about a more thorough understanding of the long-term effects of cortisol.

Cushing's disease and hypertension: in vivo and in vitro study of the role of the renin-angiotensin-aldosterone system and effects of medical therapy

OBJECTIVE/METHODS

Cushing's disease (CD) is often accompanied by hypertension. CD can be treated surgically and, given the expression of somatostatin subtype 5 and dopamine 2 receptors by corticotroph pituitary adenomas, pharmacologically. Indeed, we recently observed that stepwise medical combination therapy with the somatostatin-analog pasireotide, the dopamine-agonist cabergoline, and ketoconazole (which directly suppresses steroidogenesis) biochemically controlled CD patients and lowered their blood pressure after 80 days. Glucocorticoids (GC) modulate the renin-angiotensin-aldosterone system (RAAS) among others by increasing hepatic angiotensinogen expression and stimulating mineralocorticoid receptors (MR). This study therefore evaluated plasma RAAS components in CD patients before and after drug therapy. In addition, we studied whether cabergoline/pasireotide have direct relaxant effects in angiotensin II (Ang II)-constricted iliac arteries of spontaneously hypertensive rats, with and without concomitant GR/MR stimulation with dexamethasone or hydrocortisone.

RESULTS

Baseline concentrations of angiotensinogen were elevated, while renin and aldosterone were low and suppressed, respectively, even in patients treated with RAAS-blockers. This pattern did not change after 80 days of treatment, despite blood pressure normalization, nor after 4 years of remission. In the presence of dexamethasone, pasireotide inhibited Ang II-mediated vasoconstriction.

CONCLUSIONS

The low plasma renin concentrations, even under RAAS blockade, in CD may be the consequence of increased GC-mediated MR stimulation and/or the elevated angiotensinogen levels in such patients. The lack of change in RAAS-parameters despite blood pressure and cortisol normalization suggests persisting consequences of long-term exposure to cortisol excess. Finally, pasireotide may have a direct vasodilating effect contributing to blood pressure lowering.

In active acromegaly, IGF1 bioactivity is related to soluble Klotho levels and quality of life

The value of measuring IGF1 bioactivity in active acromegaly is unknown. Soluble Klotho (S-Klotho) level is elevated in active acromegaly and it has been suggested that S-Klotho can inhibit activation of the IGF1 receptor (IGF1R). A cross-sectional study was carried out in 15 patients with active acromegaly based on clinical presentation, unsuppressed GH during an oral glucose tolerance test, and elevated total IGF1 levels (>+2 s.d.). Total IGF1 was measured by immunoassay, IGF1 bioactivity by the IGF1R kinase receptor activation assay and S-Klotho by an ELISA. Quality of Life (QoL) was assessed by Acromegaly QoL (AcroQoL) Questionnaire and Short-Form-36 Health Survey Questionnaire (SF-36). Out of 15 patients, nine had IGF1 bioactivity values within the reference range. S-Klotho was higher in active acromegaly compared with controls. Age-adjusted S-Klotho was significantly related to IGF1 bioactivity (r=0.75, P=0.002) and to total IGF1 (r=0.62, P=0.02). IGF1 bioactivity and total IGF1 were inversely related to the physical component summary of the SF-36 (r=-0.78, P=0.002 vs r=-0.60, P=0.03). Moreover, IGF1 bioactivity, but not total IGF1, was significantly inversely related to the physical dimension of the AcroQoL Questionnaire (r=-0.60, P=0.02 vs r=-0.37, P=0.19). In contrast to total IGF1, IGF1 bioactivity was within the reference range in a considerable number of subjects with active acromegaly. Elevated S-Klotho levels may have reduced IGF1 bioactivity. Moreover, IGF1 bioactivity was more strongly related to physical measures of QoL than total IGF1, suggesting that IGF1 bioactivity may better reflect physical limitations perceived in active acromegaly.

β-Arrestin 1 and 2 and G protein-coupled receptor kinase 2 expression in pituitary adenomas: role in the regulation of response to somatostatin analogue treatment in patients with acromegaly

Recent in vitro studies highlighted G protein-coupled receptor kinase (GRK)2 and β-arrestins as important players in driving somatostatin receptor (SSTR) desensitization and trafficking. Our aim was to characterize GRK2 and β-arrestins expression in different pituitary adenomas and to investigate their potential role in the response to somatostatin analog (SSA) treatment in GH-secreting adenomas (GHomas). We evaluated mRNA expression of multiple SSTRs, GRK2, β-arrestin 1, and β-arrestin 2 in 41 pituitary adenomas (31 GHomas, 6 nonfunctioning [NFPAs], and 4 prolactinomas [PRLomas]). Within the GHomas group, mRNA data were correlated with the in vivo response to an acute octreotide test and with the GH-lowering effect of SSA in cultured primary cells. β-Arrestin 1 expression was low in all 3 adenoma histotypes. However, its expression was significantly lower in GHomas and PRLomas, compared with NFPAs (P < .01). GRK2 expression was higher in PRLomas and NFPAs compared with GHomas (P < .05). In the GHoma group, GRK2 expression was inversely correlated to β-arrestin 1 (P < .05) and positively correlated to β-arrestin 2 (P < .0001). SSA treatment did not affect GRK2 and β-arrestin expression in GHomas or in cultured rat pituitary tumor GH3 cells. Noteworthy, β-arrestin 1 was significantly lower (P < .05) in tumors responsive to octreotide treatment in vitro, whereas GRK2 and SSTR subtype 2 were significantly higher (P < .05). Likewise, β-arrestin 1 levels were inversely correlated with the in vivo response to acute octreotide test (P = .001), whereas GRK2 and SSTR subtype 2 expression were positively correlated (P < .05). In conclusion, for the first time, we characterized GRK2, β-arrestin 1, and β-arrestin 2 expression in a representative number of pituitary adenomas. β-Arrestin 1 and GRK2 seem to have a role in modulating GH secretion during SSA treatment.

Preoperative normalization of cortisol levels in Cushing's disease after medical treatment: consequences for somatostatin and dopamine receptor subtype expression and in vitro response to somatostatin analogs and dopamine agonists

CONTEXT

Corticotroph pituitary adenomas often highly express the dopamine 2 receptor (D₂R) and somatostatin receptor subtype 5 (sst₅). The sst₂ expression is relatively low, likely resulting from downregulating effects of high cortisol levels. This may explain why the sst₂-preferring somatostatin analog octreotide, compared with the multi-receptor-targeting somatostatin analog pasireotide, is generally ineffective in Cushing's disease.

OBJECTIVE

Our objective was to compare sst and D₂R expression levels between adenomas from patients with elevated and normalized preoperative urinary free cortisol excretion.

PATIENTS AND DESIGN

Corticotroph adenoma tissue was examined from patients from group 1 (n = 22; elevated preoperative urinary free cortisol) and group 2 (n = 11; mean duration of preoperative normocortisolism 10 weeks). Somatotroph adenoma tissue from 10 acromegalic patients was examined to compare receptor expression profiles.

MAIN OUTCOME MEASURES

We evaluated receptor mRNA and protein expression levels and effects of octreotide, pasireotide, and cabergoline on ACTH secretion by cultured human corticotroph adenoma cells.

RESULTS

The sst₂ mRNA expression in group 2 was 10-fold higher than in group 1 (P < .01), even comparable to that in somatotroph adenomas. There were no statistically significant differences in sst₅ and D₂R mRNA expression or in sst₂, sst₅, and D₂R protein expression between both groups of corticotroph adenomas. In responders, octreotide (n = 2 out of 4; -30.5% ± 10.4%) was less potent than pasireotide (n = 5 out of 6; -47.0% ± 4.2%) and cabergoline (n = 3 out of 4; -41.9% ± 3.1%) with respect to inhibition of ACTH secretion by adenomas from group 2.

CONCLUSIONS

After achieving normocortisolism induced by medical therapy, cortisol-mediated sst₂ downregulation on corticotroph adenomas appears to be a reversible process at the mRNA but not at the protein level. Octreotide remains less potent than pasireotide and cabergoline with respect to in vitro inhibition of ACTH secretion. Whether sustained normocortisolism induced by medical therapy induces re-expression of functional sst₂ protein in corticotroph adenomas and whether this increases the ACTH-lowering potency of octreotide remains to be established.

Cortisol diurnal rhythm and quality of life after successful medical treatment of Cushing's disease

Cushing's disease (CD) is associated with severely impaired quality of life (QoL). Moreover, the physiological cortisol diurnal rhythm (CDR) is disturbed in CD. QoL can improve after successful surgery, the primary treatment for CD. We evaluated the effects of medical treatment on QoL and CDR. In 17 patients, stepwise medical treatment was applied with the somatostatin analog pasireotide, the dopamine agonist cabergoline and the adrenal-blocking agent ketoconazole. After 80 days, 15/17 (88%) patients had reached normal urinary free cortisol excretion (UFC). Subsequently, patients continued medical therapy or underwent surgery. UFC, plasma and salivary CDR and QoL-related parameters (assessed using 5 questionnaires: Nottingham Health Profile, Hospital Anxiety and Depression Scale, Multidimensional Fatigue Index-20, RAND-36, CushingQoL) were measured. At baseline, 5/17 patients had preserved CDR. In 6/12 patients with disturbed baseline CDR, recovery was observed, but without any correlation with QoL. QoL was significantly impaired according to 18/20 subscales in CD patients compared to literature-derived controls. According to the RAND-36 questionnaire, patients reported more pain at day 80 (p < 0.05), which might reflect steroid-withdrawal. Generally, QoL did not improve or deteriorate after 80 days. CushingQoL scores seemed to improve after 1 year of remission in three patients that continued medical therapy (p = 0.11). CDR can recover during successful pituitary- and adrenal-targeted medical therapy. Patients with CD have impaired QoL compared to controls. Despite the occurrence of side-effects, QoL does not deteriorate after short-term biochemical remission induced by medical therapy, but might improve after sustained control of hypercortisolism.

Glucocorticoid sensitivity in health and disease

Glucocorticoids regulate many physiological processes and have an essential role in the systemic response to stress. For example, gene transcription is modulated by the glucocorticoid-glucocorticoid receptor complex via several mechanisms. The ultimate biologic responses to glucocorticoids are determined by not only the concentration of glucocorticoids but also the differences between individuals in glucocorticoid sensitivity, which is influenced by multiple factors. Differences in sensitivity to glucocorticoids in healthy individuals are partly genetically determined by functional polymorphisms of the gene that encodes the glucocorticoid receptor. Hereditary syndromes have also been identified that are associated with increased and decreased sensitivity to glucocorticoids. As a result of their anti-inflammatory properties, glucocorticoids are widely used in the treatment of allergic, inflammatory and haematological disorders. The variety in clinical responses to treatment with glucocorticoids reflects the considerable variation in glucocorticoid sensitivity between individuals. In immune-mediated disorders, proinflammatory cytokines can induce localized resistance to glucocorticoids via several mechanisms. Individual differences in how tissues respond to glucocorticoids might also be involved in the predisposition for and pathogenesis of the metabolic syndrome and mood disorders. In this Review, we summarize the mechanisms that influence glucocorticoid sensitivity in health and disease and discuss possible strategies to modulate glucocorticoid responsiveness.

Interferon-β is a potent inhibitor of cell growth and cortisol production in vitro and sensitizes human adrenocortical carcinoma cells to mitotane

Adrenocortical carcinoma (ACC) is an aggressive tumor with very poor prognosis. Novel medical treatment opportunities are required. We investigated the effects of interferon-β (IFN-β), alone or in combination with mitotane, on cell growth and cortisol secretion in primary cultures of 13 human ACCs, three adrenal hyperplasias, three adrenal adenomas, and in two ACC cell lines. Moreover, the interrelationship between the effects of IGF2 and IFN-β was evaluated. Mitotane inhibited cell total DNA content/well (representing cell number) in 7/11 (IC50: 38±9.2 μM) and cortisol secretion in 5/5 ACC cultures (IC50: 4.5±0.1 μM). IFN-β reduced cell number in 10/11 (IC50: 83±18 IU/ml) and cortisol secretion in 5/5 ACC cultures (IC50: 7.3±1.5 IU/ml). The effect of IFN-β on cell number included the induction of apoptosis. IFN-β strongly inhibited mRNA expression of STAR, CYP11A1, CYP17A1, and CYP11B1. Mitotane and IFN-β induced an additive inhibitory effect on cell number and cortisol secretion. IGF2 (10 nM) inhibited apoptosis and increased cell number and cortisol secretion. These effects were counteracted by IFN-β treatment. Finally, IFN-β inhibited IGF2 secretion and mRNA expression. In conclusion, IFN-β is a potent inhibitor of ACC cell growth in human primary ACC cultures, partially mediated by an inhibition of the effects of IGF2, as well as its production. The increased sensitivity of ACC cells to mitotane induced by treatment with IFN-β may open the opportunity for combined treatment regimens with lower mitotane doses. The inhibition of the expression of steroidogenic enzymes by IFN-β is a novel mechanism that may explain its inhibitory effect on cortisol production.

Expression of 11β-hydroxysteroid dehydrogenase type 1 in the human hypothalamus

The hypothalamus is a major target for glucocorticoids and a key structure for hypothalamic-pituitary-adrenal (HPA) axis setpoint regulation. The enzyme 11β hydroxysteroid dehydrogenase type 1 (11βHSD1) modulates glucocorticoid signalling in various tissues at the prereceptor level by converting biologically inactive cortisone to its active form cortisol. The present study aimed to assess 11βHSD1 expression in the human hypothalamus. We studied 11βHSD1 expression in five frozen and four formalin-fixed, paraffin-embedded human hypothalami (obtained from the Netherlands Brain Bank) by the polymerase chain reaction and immunocytochemistry, respectively. 11βHSD1 mRNA was expressed in the area of the suprachiasmatic nucleus, which is the biological clock of the brain, in the supraoptic nucleus and paraventricular nucleus (PVN), and in the infundibular nucleus, which is the human homologue of the rodent arcuate nucleus. 11βHSD1 was detected by immunocytochemistry in the same nuclei. In the PVN, neuronal 11βHSD1 immunoreactivity colocalised with corticotrophin-releasing hormone (CRH), arginine vasopressin and oxytocin, as shown by dual fluorescence staining. Our data demonstrate that 11βHSD1 is widely expressed in the human hypothalamus. Its colocalisation with CRH in the PVN suggests a role in modulation of glucocorticoid feedback of the HPA axis, whereas the expression of 11βHSD1 in additional and functionally diverse hypothalamic nuclei points to a role for the enzyme in the regulation of metabolism, appetite and circadian rhythms.

IGF-I bioactivity might reflect different aspects of quality of life than total IGF-I in GH-deficient patients during GH treatment

CONTEXT

No relationship has been found between improvement in quality of life (QOL) and total IGF-I during GH therapy.

AIM

Our aim was to investigate the relationship between IGF-I bioactivity and QOL in GH-deficient (GHD) patients receiving GH for 12 months.

METHODS

Of 106 GHD patients, 84 on GH treatment discontinued therapy 4 weeks before establishing baseline values and 22 were GH-naive. IGF-I bioactivity was determined by IGF-I kinase receptor activation assay, total IGF-I by immunoassay (Immulite), and QOL by the disease-specific Question on Life Satisfaction Hypopituitarism (QLS-H) module and by the general SF-36 questionnaire (SF-36Q).

RESULTS

IGF-I bioactivity increased after 6 months (-2.5 vs -1.9 SD, P < .001) and did not further increase after 12 months (-1.8 SD, P = .23); total IGF-I increased from -2.3 to -0.9 SD (P < .001) and to -0.6 SD (P = .005), respectively. QLS-H did not change over 12 months (-0.66 ± 0.16 to -0.56 ± 0.17 SD [P = .42] to -0.68 ± 0.17 SD [P = .22]). The mental component summary of the SF-36Q increased from 47.4 (38.7-52.8) to 50.2 (43.1-55.3) (P = .001) and did not further improve (49.4 [42.1-54.1], P = .19); the physical component summary did not change (47.5 [42.0-54.2] vs 47.0 [41.9-55.3], P = .91, vs 48.3 [39.9-55.4], P = .66). After 12 months, IGF-I bioactivity was related to QLS-H (r = 0.28, P = .01); total IGF-I was not (r = 0.10, P = .37). IGF-I bioactivity and total IGF-I were related to PCS (r = 0.35, P = .001; and r = 0.31, P = .003).

CONCLUSION

IGF-I bioactivity remained subnormal after GH treatment and was positively related to QLS-H, whereas total IGF-I was not. This suggests that IGF-I bioactivity reflects different aspects of QOL than total IGF-I in GHD patients during GH treatment.

Circulating IgGs may modulate IGF-I receptor stimulating activity in a subset of patients with Graves' ophthalmopathy

CONTEXT

There is a close association between levels of TSH binding inhibitory immunoglobulins (TBIIs) and Graves' ophthalmopathy (GO). In addition to the TSH receptor, the IGF-I receptor (IGF-IR) has been proposed to be a second autoantigen that plays a role in the pathogenesis of GO.

OBJECTIVE

The aim was to study relationships between TBII and serum IGF-IR stimulating activity in relationship to age in patients with GO.

METHODS

We performed a prospective study of 70 patients with GO (26 euthyroid, 39 subclinical hyperthyroid, 5 hyperthyroid; 8 males, 62 females; age, 47.9 ± 1.0 y). Patients were graded according to clinical activity score. IGF-IR stimulating activity was determined by IGF-IR kinase receptor activation assay; TBIIs were measured by immunoassay (Trak). Protein G magnetic beads were used to deplete serum of IgGs.

RESULTS

TBII and clinical activity score were positively related (r = 0.30; P = .01). In subjects with TBII above mean +1 SD, IGF-IR stimulating activity was positively related to age (r = 0.43; P = .05), whereas such a relationship was absent for subjects with TBII below the mean +1 SD (r = -0.04; P = .81). Depletion of IgGs from sera of patients with both TBII above the mean +1 SD and IGF-IR stimulating activity above the mean -1 SD decreased IGF-IR stimulating activity, whereas depletion in patients with TBII above the mean +1 SD but IGF-IR stimulating activity below the mean -1 SD did not change IGF-IR stimulating activity.

CONCLUSIONS

In subjects with TBII above the mean +1 SD, we observed an increase of IGF-IR stimulating activity with age. In a subgroup of these patients, depletion of IgGs significantly decreased IGF-IR stimulating activity, suggesting that, in a subset of patients with GO, IgGs may have IGF-IR stimulating activities.

Atherosclerosis and physical functioning in older men, a longitudinal study

OBJECTIVE

Functional decline is a major threat to independency, progressing into functional limitations and eventually leading to disability. Chronic diseases, especially cardiovascular diseases, are important determinants of functional limitations and disability. Vascular damage exits long before it is clinically manifest and can have adverse effects on health, physical and cognitive functioning. The objective was to investigate the association between non-invasive atherosclerosis measures and physical functioning in older men.

DESIGN

Prospective cohort study.

SETTING

The study was conducted in the general community.

PARTICIPANTS

195 independently living older men.

MEASUREMENTS

Atherosclerosis was measured by intima media thickness (CIMT) of the common carotid artery using ultrasonography and assessment for presence of atherosclerotic plaques. Physical functioning was measured by isometric handgrip strength and leg extensor strength using a hand held dynamometer, lower extremity function using the physical performance score and ability to perform activities of daily life using the modified Stanford health assessment questionnaire. Linear regression analysis was performed to estimate the associations between CIMT or plaques and physical functioning.

RESULTS

After adjustment for confounders, higher baseline CIMT was associated with lower isometric handgrip strength at follow up (βCIMT = -7.21, 95% CI[-13.64;-0.77]). No other associations were found between CIMT and physical functioning. In addition, no associations were found for the presence of plaques and physical functioning either at baseline, or at follow-up.

CONCLUSION

Atherosclerosis, as measured by higher CIMT, is related to a lower isometric handgrip strength at follow-up, but no further associations with physical functioning were found in this longitudinal study among independently living older men.

Immunoreactivity score using an anti-sst2A receptor monoclonal antibody strongly predicts the biochemical response to adjuvant treatment with somatostatin analogs in acromegaly

CONTEXT

Somatostatin receptor subtype 2 (sst2A) protein expression has been demonstrated to positively correlate with somatostatin analog treatment outcome in GH-secreting adenomas. Recently, a new rabbit monoclonal anti-sst2A antibody (clone UMB-1) has been validated as a reliable method to selectively detect sst2A protein levels in formalin-fixed tissues.

OBJECTIVE

The aim of the study was to establish whether the evaluation of sst2A protein levels, assessed with a routine reproducible immunohistochemistry protocol using UMB-1 antibody, may predict the successful adjuvant therapy with somatostatin analogs in acromegalic patients.

DESIGN, SETTING, AND PATIENTS

Thirty-six acromegalic patients from our referral hospital were evaluated retrospectively. Sst2A expression analysis was performed by immunohistochemistry in 25 patients and by quantitative RT-PCR in 26 patients. Sst2A immunoreactivity was evaluated using an immunoreactivity score (IRS), which takes into account both the percentage of positive cells and staining intensity.

INTERVENTIONS

Patients with persistent disease after surgery (n = 26) were treated with somatostatin analogs for a median duration of 6 months.

MAIN OUTCOME MEASURE

GH and IGF-I levels were measured before and after postoperative treatment.

RESULTS

Sst2A IRS showed a significant positive correlation with both GH (P = 0.039) and IGF-I (P = 0.001) suppression by octreotide. Sst2A IRS was negatively associated with IGF-I levels reached after treatment (P = 0.001), and patients that achieved IGF-I normalization showed significantly higher sst2A IRS compared to the group that was not normalized (P = 0.002). A sst2A IRS of at least 5 showed a sensitivity of 86% and a specificity of 91% in predicting IGF-I normalization during adjuvant octreotide treatment.

CONCLUSION

Sst2A IRS with the anti-sst2A antibody UMB-1 represents a valid tool in the clinical practice to identify acromegalic patients likely to be responders to adjuvant therapy with the currently available somatostatin analogs.

Glucocorticoid sensitivity in Behçet's disease

OBJECTIVE

Glucocorticoid (GC) sensitivity is highly variable among individuals and has been associated with susceptibility to develop (auto-)inflammatory disorders. The purpose of the study was to assess GC sensitivity in Behçet's disease (BD) by studying the distribution of four GC receptor (GR) gene polymorphisms and by measuring in vitro cellular GC sensitivity.

METHODS

Healthy controls and patients with BD in three independent cohorts were genotyped for four functional GR gene polymorphisms. To gain insight into functional differences in in vitro GC sensitivity, 19 patients with BD were studied using two bioassays and a whole-cell dexamethasone-binding assay. Finally, mRNA expression levels of GR splice variants (GR-α and GR-β) were measured.

RESULTS

Healthy controls and BD patients in the three separate cohorts had similar distributions of the four GR polymorphisms. The Bcll and 9β minor alleles frequency differed significantly between Caucasians and Mideast and Turkish individuals. At the functional level, a decreased in vitro cellular GC sensitivity was observed. GR number in peripheral blood mononuclear cells was higher in BD compared with controls. The ratio of GR-α/GR-β mRNA expression levels was significantly lower in BD.

CONCLUSIONS

Polymorphisms in the GR gene are not associated with susceptibility to BD. However, in vitro cellular GC sensitivity is decreased in BD, possibly mediated by a relative higher expression of the dominant negative GR-β splice variant. This decreased in vitro GC sensitivity might play an as yet unidentified role in the pathophysiology of BD.

In vitro glucocorticoid sensitivity is associated with clinical glucocorticoid therapy outcome in rheumatoid arthritis

Introduction

Genetic and disease-related factors give rise to a wide spectrum of glucocorticoid (GC) sensitivity in rheumatoid arthritis (RA). In clinical practice, GC treatment is not adapted to these differences in GC sensitivity. In vitro assessment of GC sensitivity before the start of therapy could allow more individualized GC therapy. The aim of the study was to investigate the association between in vitro and in vivo GC sensitivity in RA.

Methods

Thirty-eight early and 37 established RA patients were prospectively studied. In vitro GC sensitivity was assessed with dexamethasone-induced effects on interleukin-2 (IL-2) and glucocorticoid-induced leucine zipper (GILZ) messenger RNA expression in peripheral blood mononuclear cells (PBMCs). A whole-cell dexamethasone-binding assay was used to measure number and affinity (1/K_D) of glucocorticoid receptors (GRs).

In vivo GC sensitivity was determined by measuring the disease activity score (DAS) and health assessment questionnaire disability index (HAQ-DI) score before and after 2 weeks of standardized GC treatment.

Results

GR number was positively correlated with improvement in DAS. IL-2-EC₅₀ and GILZ-EC₅₀ values both had weak near-significant correlations with clinical improvement in DAS in intramuscularly treated patients only. HAQ responders had lower GILZ-EC₅₀ values and higher GR number and K_D.

Conclusions

Baseline cellular in vitro glucocorticoid sensitivity is modestly associated with in vivo improvement in DAS and HAQ-DI score after GC bridging therapy in RA. Further studies are needed to evaluate whether in vitro GC sensitivity may support the development of tailor-made GC therapy in RA.

Glucocorticoid receptor gene polymorphisms and disease activity during pregnancy and the postpartum period in rheumatoid arthritis

INTRODUCTION

The mechanism underlying the spontaneous improvement of rheumatoid arthritis (RA) during pregnancy and the subsequent postpartum flare is incompletely understood, and the disease course varies widely between pregnant RA patients. In pregnancy, total and free levels of cortisol increase gradually, followed by a postpartum decrease to prepregnancy values. The glucocorticoid receptor (GR) polymorphisms BclI and N363S are associated with relatively increased glucocorticoid (GC) sensitivity, whereas the 9β and ER22/23EK polymorphisms of the GR gene are associated with a relatively decreased GC sensitivity. We examined the relation between the presence of these GR polymorphisms and level of disease activity and disease course of RA during pregnancy and postpartum.

METHODS

We studied 147 participants of the PARA study (Pregnancy-Induced Amelioration of Rheumatoid Arthritis study), a prospective study investigating the natural improvement during pregnancy and the postpartum flare in women with RA. Patients were visited, preferably before pregnancy, at each trimester and at three postpartum time points. On all occasions, disease activity was scored by using DAS28. All patients were genotyped for the GR polymorphisms BclI, N363S, 9β, and ER22/23EK and divided in groups harboring either polymorphisms conferring increased GC sensitivity (BclI and N363S; GC-S patients) or polymorphisms conferring decreased GC sensitivity (9β or 9β + ER22/23EK; GC-I patients). Data were analyzed by using a mixed linear model, comparing GC-S patients with GC-I patients with respect to improvement during pregnancy and the postpartum flare. The cumulative disease activity was calculated by using time-integrated values (area under the curve, AUC) of DAS28 in GC-I patients versus GC-S patients. Separate analyses were performed according to the state of GC use.

RESULTS

GC-S patients treated with GC had a significantly lower AUC of DAS28 in the postpartum period than did GC-I patients. This difference was not observed in patients who were not treated with GCs. During pregnancy, GC-S and GC-I patients had comparable levels of disease activity and course of disease.

CONCLUSIONS

Differences in relative GC sensitivity, as determined by GR polymorphisms, are associated with the level of disease activity in the postpartum period in GC-treated patients, but they do not seem to influence the course of the disease per se.

High IGFBP2 levels are not only associated with a better metabolic risk profile but also with increased mortality in elderly men

OBJECTIVE

Serum IGF-binding protein 2 (IGFBP2) concentrations are reduced in obese humans and increase after a prolonged period of fasting. We investigated the association between IGFBP2 levels and mortality together with other factors that are related to IGFBP2, including the metabolic syndrome and physical function.

DESIGN

A prospective observational study at a clinical research center of 403 independently living elderly men (aged 73-94 years).

METHODS

Mortality was registered during 8.6 years of follow-up. Physical performance score (PPS), grip strength (GS), and bone mineral density (BMD) were measured. The measurements taken a baseline were: IGF1; IGFBP1, -2, and -3; IGF1 bioactivity; triiodothyronine (T(3)); and reverse T(3). Further, BMI, insulin sensitivity, cholesterol, inflammatory markers, and albumin levels were also measured.

RESULTS

During the follow-up, 180 men died. Higher PPS, GS, and BMD were independently related to a reduced mortality (hazard ratio (HR)=0.87/point, 95% confidence interval (95% CI)=0.82-0.91, P<0.001; HR=0.96/kp, 95% CI 0.94-0.98, P<0.001; and HR=0.21/(g/cm(2)), 95% CI 0.07-0.61, P<0.01). Higher serum IGFBP2 levels were strongly related to mortality (HR=2.26/(mg/l), 95% CI 1.57-3.27, P<0.001). This was independent of comorbidity, physical function, IGF1 bioactivity, and other somatotropic parameters, including BMI and the metabolic syndrome. In addition, IGFBP2 levels were higher in subjects with nonthyroidal illness, and higher IGFBP2 levels were significantly associated with lower albumin concentrations.

CONCLUSION

Despite the strong relationship between high IGFBP2 and low physical function, both were strongly and independently related to increased 8-year mortality in elderly men. IGFBP2 may be a useful biomarker integrating the nutritional status, as well as the biological effects of GH, IGF1, and insulin.

The role of mTOR inhibitors in the inhibition of growth and cortisol secretion in human adrenocortical carcinoma cells

Patients with adrenocortical carcinoma (ACC) need new treatment options. The aim of this study was to evaluate the effects of the mTOR inhibitors sirolimus and temsirolimus on human ACC cell growth and cortisol production. In H295, HAC15, and SW13 cells, we have evaluated mTOR, IGF2, and IGF1 receptor expressions; the effects of sirolimus and temsirolimus on cell growth; and the effects of sirolimus on apoptosis, cell cycle, and cortisol production. Moreover, the effects of sirolimus on basal and IGF2-stimulated H295 cell colony growth and on basal and IGF1-stimulated phospho-AKT, phospho-S6K1, and phospho-ERK in H295 and SW13 were studied. Finally, we have evaluated the effects of combination treatment of sirolimus with an IGF2-neutralizing antibody. We have found that H295 and HAC15 expressed IGF2 at a >1800-fold higher level than SW13. mTOR inhibitors suppressed cell growth in a dose-/time-dependent manner in all cell lines. SW13 were the most sensitive to these effects. Sirolimus inhibited H295 colony surviving fraction and size. These effects were not antagonized by IGF2, suggesting the involvement of other autocrine regulators of mTOR pathways. In H295, sirolimus activated escape pathways. The blocking of endogenously produced IGF2 increased the antiproliferative effects of sirolimus on H295. Cortisol production by H295 and HAC15 was inhibited by sirolimus. The current study demonstrates that mTOR inhibitors inhibit the proliferation and cortisol production in ACC cells. Different ACC cells have different sensitivity to the mTOR inhibitors. mTOR could be a target for the treatment of human ACCs, but variable responses might be expected. In selected cases of ACC, the combined targeting of mTOR and IGF2 could have greater effects than mTOR inhibitors alone.

Immunohistochemical localization and quantitative expression of somatostatin receptors in normal human spleen and thymus: Implications for the in vivo visualization during somatostatin receptor scintigraphy

BACKGROUND

[111In-DTPA-D-Phe1]-octreotide scintigraphy allows the visualization of SRIF receptor (SSR)-expressing tumors, including thymic tumors, and normal tissues. While the spleen is clearly visualized, the thymus is not depicted, although both contain SSR.

AIM

We evaluated whether the heterogeneity, the type, and the amount of SSR might explain this contrasting finding.

MATERIALS, METHODS, AND RESULTS

By ligand-binding the number of [125I-Tyr11]-SRIF- 14 binding sites resulted comparable between the two tissues, whereas the number of [125I-Tyr3]-octreotide sites was significantly higher in the spleen (p<0.001). Quantitative RTPCR showed a significantly higher expression of sst2A mRNA in the spleen, whereas a significantly higher expression of SRIF and sst3 in the thymus. The highest density of sst2A in the spleen is in line with the in vivo uptake of [111In-DTPA-D-Phe1]- octreotide, which is considered a sst2-preferring ligand. The specificity is confirmed by the evidence that in vivo [111In-DTPA- D-Phe1]-octreotide uptake can be abolished during chronic administration of "cold" octreotide. Immunohistochemistry confirmed a preferential expression of sst2A on microenvironmental cells and of sst3 on lymphoid cells.

CONCLUSIONS

The heterogeneity of SSR expression and the higher SRIF content explain the lack of thymus visualization during scintigraphy, whereas thymic tumors, which do not express SRIF, are visualized. Apart from the affinity of the radioligand, also the efficacy of the internalization is crucial for the in vivo uptake, and both heterogeneity and SRIF content affect this process. These observations might have an important impact when interpretating in vivo visualization of SSR-positive lesions, and when treatment with novel SRIF analogs is considered.

The hypercoagulable state in Cushing's disease is associated with increased levels of procoagulant factors and impaired fibrinolysis, but is not reversible after short-term biochemical remission induced by medical therapy

CONTEXT

Cushing's disease (CD) is accompanied by an increased risk of venous thromboembolism. Surgery is the primary treatment of CD.

OBJECTIVE

The aim of the study was to compare hemostatic parameters between patients with CD and controls and to evaluate the effect of medical treatment of CD on hemostasis.

DESIGN AND SETTING

During 80 d, stepwise medical treatment was applied with the somatostatin analog pasireotide, the dopamine agonist cabergoline, and ketoconazole, which suppresses adrenocortical steroidogenesis, at four university medical centers in The Netherlands.

PATIENTS

Seventeen patients with de novo, residual, or recurrent CD were included.

MAIN OUTCOME MEASURES

We measured urinary free cortisol and parameters of coagulation and fibrinolysis.

RESULTS

Patients with CD had significantly higher body mass index (P < 0.001), shortened activated partial thromboplastin time (P < 0.01), and higher levels of fibrinogen, Factor VIII, and protein S activity (P < 0.05) compared to healthy control subjects. In addition, fibrinolytic capacity was impaired in patients with CD as reflected by prolonged clot lysis time (P < 0.001) and higher levels of plasminogen activator inhibitor type 1, thrombin-activatable fibrinolysis inhibitor, and α2-antiplasmin (P < 0.01). There were no statistically significant differences in von Willebrand factor:antigen, antithrombin, and protein C activity. After 80 d, 15 of 17 patients had normalized urinary free cortisol excretion. Despite biochemical remission, only slight decreases in antithrombin (P < 0.01) and thrombin-activatable fibrinolysis inhibitor (P < 0.05) levels were observed. Other parameters of coagulation and fibrinolysis did not change significantly.

CONCLUSIONS

The hypercoagulable state in patients with CD, which is explained by both increased production of procoagulant factors and impaired fibrinolysis, is not reversible upon short-term biochemical remission after successful medical therapy. This may have implications for the duration of anticoagulant prophylaxis in patients with (cured) CD.

Mifepristone effects on tumor somatostatin receptor expression in two patients with Cushing's syndrome due to ectopic adrenocorticotropin secretion

CONTEXT

Two patients presented with Cushing's syndrome due to ectopic ACTH secretion. Initial localization studies included computed tomography, magnetic resonance imaging, and octreoscans ((111)In-pentreotide scintigraphy), which were negative in both patients. They were treated with the glucocorticoid receptor antagonist mifepristone, with improvement in their clinical symptoms. Follow-up octreoscans after, respectively, 6 and 12 months showed the unequivocal presence of a bronchial carcinoid in both patients.

OBJECTIVE

The objective of the study was to correlate in vivo and in vitro findings in patients with ectopic ACTH-producing syndrome.

METHODS

We determined the expression of somatostatin and dopamine receptors by immunohistochemistry (patients 1 and 2), quantitative PCR, and in vitro culturing of tumor cells (patient 1 only). IN VITRO RESULTS: Both tumors were strongly positive for somatostatin receptor type 2 (sst(2)) on immunohistochemistry, whereas one of the tumors (patient 1) was also dopamine receptor subtype 2 (D(2)) positive on both immunohistochemistry and quantitative PCR. Octreotide (a sst(2) preferring analog) and cabergoline (D(2) agonist) both decreased the ACTH levels in the cultured tumor cells of patient 1.

CONCLUSION

We describe two patients with ACTH-producing bronchial carcinoids, in whom a direct down-regulatory effect of glucocorticoid levels on tumoral sst(2) receptor expression is suggested by a remarkable change in octreoscan status after successful mifepristone therapy. Further studies will have to demonstrate whether glucocorticoid lowering or antagonizing therapy may be used to improve the diagnostic accuracy of somatostatin receptor scintigraphy in patients with ectopic ACTH production of unknown primary origin.

The effect of common genetic variation in 11β-hydroxysteroid dehydrogenase type 1 on hypothalamic-pituitary-adrenal axis activity and incident depression

BACKGROUND

Accumulating evidence suggests that hyperactivity of the hypothalamic-pituitary-adrenal axis (HPA axis) is involved in depression. 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) converts inert cortisone to active cortisol and is implicated in HPA axis regulation in animal studies. The aim of our study was to identify polymorphisms in 11β-HSD1 gene (HSD11B1) with consistent associations with increased HPA axis activity and relate those polymorphisms to depression.

METHODS

Twelve single-nucleotide polymorphisms (SNPs), including 11 tagging SNPs, were selected using the HapMap database and genotyped in 4228 participants of the population-based Rotterdam Study. The outcome measures were salivary cortisol levels after awakening, 30 min later, at 1700 h, at bedtime, and plasma levels of androstenedione (in women only). SNPs that were significantly associated with cortisol as well as androstenedione levels were also related to incident depression.

RESULTS

rs11119328 was associated with higher cortisol saliva samples collected at bedtime as well as higher androstenedione levels (P value after correction for multiple testing: 0.01 and 0.04, respectively). Carriers of this polymorphism had an increased risk of an incident depression (hazard ratio 1.28, 95% confidence interval 1.03-1.59). Two other SNPs, which were in high linkage disequilibrium with rs11119328, were related to higher cortisol levels but not with androstenedione levels.

CONCLUSIONS

We identified one SNP, which was associated with increased salivary cortisol levels at nadir as well as higher androstenedione levels. Moreover, this SNP was also associated with a higher risk of an incident depression. This suggests that 11β-HSD1 is implicated in human HPA axis regulation and susceptibility to depression.

Estrogen receptor-alpha gene polymorphisms and body composition in children and adolescents

BACKGROUND/AIMS

Gender differences in body composition are largely explained by differences in sex hormones, such as estrogens. Associations between 2 polymorphisms in the estrogen receptor-α gene (ESR1) and body composition in children and adolescents were investigated.

METHODS

Two comparable Dutch cohorts with a generational difference of about 20 years were investigated. The first consisted of 350 subjects (184 girls) and the second of 316 subjects (155 girls). Associations between height, weight, BMI, fat mass (FM) and fat-free mass and two polymorphisms in the ESR1 gene were investigated.

RESULTS

In girls in the recent cohort, the PvuII-XbaI haplotype 2 polymorphism in the ESR1 gene was associated with a lower body weight, BMI, and FM. These associations were not observed in the older cohort. The younger cohort had a significantly higher total FM, body weight and BMI compared to the older cohort.

CONCLUSION

Because the associations between the PvuII-XbaI haplotype 2 polymorphism and body FM in girls were only found in the recent cohort, but not in a comparable, generally leaner cohort from an older generation, it is suggested that non-carriers of this polymorphism are likely to be more vulnerable to fat accumulation in today's obesity promoting environment, than carriers.

Rapid decrease in adrenal responsiveness to ACTH stimulation after successful pituitary surgery in patients with Cushing's disease

OBJECTIVE

The aim of this study was to investigate the effects of transsphenoidal surgery (TS) on the adrenal sensitivity to ACTH (adrenocorticotropin) stimulation in patients with Cushing's disease (CD).

METHODS

We measured the cortisol response to 1 μg synthetic ACTH (1-24) 6 days after pituitary surgery in 45 patients with CD. Mean follow-up period was 56·5 months (SE 4·7).

RESULTS

In 24 of 28 patients in sustained remission after pituitary surgery, peak cortisol concentrations below 774 nm (28·0 μg/dl) were recorded after stimulation with 1 μg synthetic ACTH (86%). Two patients with recurrent disease after initial remission (late relapse) also showed ACTH-stimulated peak cortisol levels below 774 nM. Fourteen of 15 patients with persistent CD after surgery (early failure) showed absolute peak cortisol levels >774 nm in response to ACTH stimulation.

CONCLUSION

Patients in remission after pituitary surgery for CD showed a rapid decrease of adrenal responsiveness to exogenous ACTH stimulation. This phenomenon may be explained by ACTH-receptor down-regulation in the adrenal cortex after complete removal of the pituitary corticotroph adenoma. In our study, the postoperative low-dose ACTH stimulation test had a sensitivity of 93% and a specificity of 87% in predicting immediate remission of CD after pituitary surgery.

Evaluation of a method to measure long term cortisol levels

INTRODUCTION

Elevated levels of cortisol are known to induce various symptoms and diseases, e.g. abdominal obesity, type 2 diabetes, osteoporosis and cardiovascular disease. Measuring serum, saliva and urine cortisol is limited to one time point. Measurement of cortisol in scalp hair is a recently developed method to measure long term cortisol levels. The aim of this study was to investigate whether hair cortisol is a feasible parameter to measure cortisol exposure.

EXPERIMENTAL

We collected hair samples of 195 healthy individuals, 9 hypercortisolemic and one hypocortisolemic patient and measured hair cortisol levels. Cortisol was extracted from scalp hair using methanol and cortisol levels were measured using a salivary ELISA kit. Measurement of waist and hip circumferences and blood pressure was performed in 46 healthy subjects.

RESULTS

We found a positive correlation between hair cortisol and both waist circumference (r=0.392, p=0.007) and waist-to-hip ratio (WHR) (r=0.425, p=0.003). No correlations were found between hair cortisol levels and BMI, blood pressure or age. There was no decline in cortisol levels in six consecutive hair segments. Hair cortisol levels were elevated in patients with known hypercortisolism (p<0.0001).

CONCLUSIONS

Hair cortisol was positively correlated with WHR, suggesting that hair cortisol reflects cortisol exposure at tissue level, which was also supported by elevated hair cortisol levels in hypercortisolemic patients and concordance between hair cortisol levels and clinical disease course. Cortisol levels in hair are slightly influenced by hair treatment but not by natural hair colour, use of hair products, gender or age.

The European Registry on Cushing's syndrome: 2-year experience. Baseline demographic and clinical characteristics

OBJECTIVE

The European Registry on Cushing's syndrome (ERCUSYN) is designed to collect prospective and follow-up data at EU level on Cushing's syndrome (CS).

DESIGN AND METHODS

Baseline data on 481 CS patients (390 females, 91 males; mean age (±s.d.): 44±14 years) collected from 36 centres in 23 countries, including new patients from 2008 and retrospective cases since 2000. Patients were divided into four major aetiologic groups: pituitary-dependent CS (PIT-CS) (66%), adrenal-dependent CS (ADR-CS) (27%), CS from an ectopic source (ECT-CS) (5%) and CS from other aetiologies (2%).

RESULTS

Proportion of men in the ECT-CS group was higher than in the other groups (P<0.05). The ADR-CS group was older than the PIT-CS (P<0.05). Prevalence of hirsutism (92%) and diabetes (74%) in ECT-CS was higher than in the other groups (P<0.05 and P<0.01 respectively). PIT-CS had more skin alterations, menstrual irregularities and hirsutism than ADR-CS (P<0.01). Reduced libido was more prevalent in men than women (P<0.01). Prevalence of spine osteoporosis was higher in men than women (P<0.05), and males had more vertebral and rib fractures than females (52 vs 18% for vertebrae; P<0.001 and 34 vs 23% for ribs; P<0.05). ECT-CS consulted a diabetologist more frequently than ADR-CS (P<0.05), while a gynaecologist was consulted more often by women with PIT-CS or ADR-CS than with ECT-CS (P<0.05). Overall, weight gain was more common in women than men (P<0.01). CushingQoL and EuroQoL visual analogue scale scores did not differ between the groups.

CONCLUSIONS

The ERCUSYN project demonstrates a heterogeneous clinical presentation of CS at a European level, depending on gender and aetiology.

Prevalence and incidence of diabetes mellitus in adult patients on growth hormone replacement for growth hormone deficiency: a surveillance database analysis

CONTEXT

GH replacement in adult GH-deficient patients may cause insulin resistance, raising concerns of potential increased risk of developing diabetes mellitus (DM).

OBJECTIVE

Our objective was to assess DM prevalence and incidence in the international Hypopituitary Control and Complications Study (HypoCCS) surveillance database.

DESIGN AND PARTICIPANTS

GH-treated patients enrolled into HypoCCS (2922 U.S. and 3709 European patients) were assessed for DM, defined as recorded on the clinical report form, reported as adverse events, fasting glucose at least 7 mmol/liter recorded at least twice, or insulin treatment reported.

RESULTS

DM prevalence was 8.2% [95% confidence interval (CI) = 7.6-8.9] overall, 11.3% in the United States and 5.7% in Europe. Incidence (n/1000 patient-years) was 9.7 (95% CI = 8.4-10.9) overall, 14.1 (11.5-16.7) in the United States, and 7.0 (5.6-8.3) in Europe. Overall incidence was 2.1 (0.9-3.3) for patients with body mass index (BMI) below 25 kg/m(2) increasing to 16.4 (13.7-19.1) for BMI over 30 kg/m(2). Obesity (BMI > 30 kg/m(2)) prevalence was higher in the United States than Europe and higher in U.S. patients than a U.S. reference population. After age, gender, and BMI adjustment, U.S. HypoCCS DM incidence was 10.6 (8.1-13.0), compared with 7.1 (6.0-8.1) in the National Health Interview Survey. In Europe, incidence for French and German patients was comparable to reference populations; for Sweden, the point estimate was higher than the reference population, but 95% CI overlapped. GH dose was not correlated with DM incidence.

CONCLUSIONS

The present analysis showed no evidence for increased DM incidence in GH-treated adult hypopituitary patients. However, those more prone to develop DM exhibited a higher than normal prevalence of obesity.

IGF-I bioactivity better reflects growth hormone deficiency than total IGF-I

CONTEXT

GH is considered the main regulator of circulating IGF-I. Total (extractable) IGF-I is therefore routinely used for diagnosis of GH deficiency (GHD) and for monitoring treatment. Methods currently used for measurement of circulating total IGF-I may be hampered by interferences of IGF-binding proteins. Recently a kinase receptor activation assay was developed to determine IGF-I bioactivity in human serum. The principle of this assay is based on quantification of IGF-I receptor activation after stimulation with serum in vitro.

OBJECTIVE

The objective of the study was to investigate the diagnostic potential of IGF-I bioactivity in adults with GHD.

DESIGN

This was a single-center observational study.

STUDY PARTICIPANTS

Ninety-four GH-untreated patients diagnosed with GHD by GH-provocative tests were included.

MAIN OUTCOME MEASURES

IGF-I bioactivity (determined by the IGF-I kinase receptor activation assay) and total IGF-I (determined by immunoassay) were measured in fasting blood samples.

RESULTS

IGF-I bioactivity was more frequently below the normal range (<-2 sd) in untreated GH-deficient patients than total IGF-I levels (81.9 vs. 61.7%, respectively), especially in patients older than 40 years of age. IGF-I bioactivity decreased with the duration of GHD, whereas total IGF-I did not. With a decreasing number of additional pituitary deficits, total IGF-I levels more frequently remained within the normal range, whereas the percentage below the normal range was high for IGF-I bioactivity, independent of additional deficits.

CONCLUSION

Determination of IGF-I bioactivity may offer advantages in the evaluation of adult GHD compared with total IGF-I as bioactivity better reflects GHD as defined by GH stimulation tests, especially in subjects older than 40 years of age.

Androgen receptor gene CAG repeat polymorphism in longitudinal height and body composition in children and adolescents

OBJECTIVE

The number of CAG repeats within the CAG repeat polymorphism of the androgen receptor (AR) gene correlates inversely with the transactivation of the receptor. We investigated the relationship between the AR CAG repeat polymorphism and longitudinal growth, puberty and body composition from prepuberty until young adult age.

DESIGN

Observational study with repeated measurements.

SUBJECTS

Two comparable young Dutch cohorts. The first cohort consisted of 226 subjects. Measurements were performed from 13 until 36 years of age. The second cohort consisted of 244 subjects. Measurements in this cohort were performed from 8 until 14 years of age.

MEASUREMENTS

Associations between height, height velocity, weight, BMI, fat mass, fat-free mass and pubertal development and CAG repeat length were measured.

RESULTS

Height-standard deviation scores (SDS) were inversely associated with AR CAG repeat length in boys at young, prepubertal and early pubertal age. This association diminishes in the following years and completely disappears after the age of 16 years. No associations were found with pubertal stage or any of the other parameters for body composition.

CONCLUSIONS

AR CAG repeat length is inversely associated with longitudinal height in young boys, before the onset of puberty. During puberty, these differences disappear, possibly overruled by a strongly developing hypothalamic-pituitary-gonadal axis.

Glucocorticoid receptor gene haplotypes are not associated with birth anthropometry, blood pressure, glucose and insulin concentrations, and body composition in subjects born small for gestational age

OBJECTIVE

Smaller size at birth has been associated with an increased risk of metabolic and cardiovascular disorders in adult life. Fetal programming of the hypothalamic-pituitary-adrenal axis has been suggested as a possible explanation. Fetal glucocorticoid (GC) overexposure has effects that suggest a role of GCs in this programming. The effects of GCs are mediated through the GC receptor (GR or NR3C1). Several functional polymorphisms have been described, which are associated with relative GC resistance or hypersensitivity. Our aim is to compare frequencies of GR haplotypes, characterized by the R23K, N363S, Bcl1, or 9β polymorphisms, in subjects born small for gestational age (SGA) and associate birth anthropometry data, response to GH treatment, blood pressure, glucose and insulin concentrations, and body composition with these haplotypes.

DESIGN

In total, 418 SGA subjects and 697 healthy controls were enrolled in this study. Methods Anthropometry data were obtained, as well as blood samples to determine fasting glucose and insulin concentrations. Dual energy X-ray absorptiometry scans were used to measure the amount of fat and lean mass.

RESULTS

No differences were found between GR haplotype frequencies in SGA children compared with healthy controls. No associations were found between GR haplotypes and birth length and birth weight, growth response during GH treatment, blood pressure, glucose and insulin concentrations, and body composition.

CONCLUSION

GR haplotypes and their effect on GC sensitivity do not seem to play a significant role in GH-induced catch-up growth and the risk factors of developing metabolic and cardiovascular disorders in adult life of SGA children.

Insulin glargine is more potent in activating the human IGF-I receptor than human insulin and insulin detemir

OBJECTIVE

To investigate whether human insulin (HI) and insulin analogues differ in their ability to activate the human IGF-I receptor (IGF-IR), the human insulin receptor A (IR-A) and the human insulin receptor B (IR-B) in vitro.

METHODS

HI, short-acting insulin analogues (insulin aspart; insulin lispro) and long-acting insulin analogues (insulin glargine; insulin detemir) were compared by using kinase receptor activation (KIRA) bioassays specific for IGF-IR, IR-A or IR-B, respectively. These assays quantify ligand activity by measuring receptor auto-phosphorylation upon ligand binding. HI and insulin analogues were tested in a range from 0.1 to 100 nM.

RESULTS

Short-acting analogues: Overall, short-acting insulin analogues did not differ substantially from HI, nor from each other. Insulin lispro was slightly more potent than HI and insulin aspart in activating the IGF-IR, only reaching statistical significance at 100 nM (p<0.01). Long-acting analogues: At <10 nM insulin glargine was as potent as HI in activating the IRs and IGF-IR. At 10-100 nM insulin glargine was significantly more potent than HI in activating the IR-B (p<0.05) and IGF-IR (p<0.001). Insulin glargine was more potent than insulin detemir in activating all three receptors (p<0.001). Insulin detemir was less potent than HI in activating the IRs at 1-10 nM (p<0.01) and IGF-IR at >1 nM (p<0.05).

CONCLUSIONS

Insulin glargine was more potent in activating the IGF-IR than HI and insulin detemir. Since KIRA bioassays do not mimic the exact in vivo situation, further research is needed to find out whether our data have implications for clinical use of insulin glargine.

Pituitary tumours: the sst/D2 receptors as molecular targets

Somatostatin (SS) and dopamine (DA) are among the key regulators of hormone secretion by the anterior pituitary gland. Concordantly, SS and DA receptors are expressed in the different pituitary cell types. SS receptors (sst) have a predominant inhibitory role in the regulation of growth hormone (GH) secretion, although the secretion of other pituitary hormones, e.g. prolactin (PRL), thyroid stimulating hormone (TSH) and adrenocorticotropic hormone (ACTH) is regulated by SS as well. DA receptors, in particular the D2 receptor (D2), has an important regulatory role in the control of PRL secretion. The inhibitory effects by SS and DA may be influenced by physiological feedback mechanisms, in part also involving modulation of pituitary sst and D2 expression. Pituitary tumours express both sst and/or D2 receptors. Targeting SS and DA receptors is used clinically to control hormonal hypersecretion by pituitary tumours, as well as tumour growth. The sst subtype, as well as the co-expression of sst and D2, has significant impact on the possibility to treat patients with pituitary tumours with SS analogues and DA agonists. In this review the current knowledge on the expression and functional roles of sst and D2 in pituitary tumours is discussed.

Polymorphisms in the glucocorticoid receptor gene that modulate glucocorticoid sensitivity are associated with rheumatoid arthritis

Introduction

The glucocorticoid receptor (GR) plays an important regulatory role in the immune system. Four polymorphisms in the GR gene are associated with differences in glucocorticoid (GC) sensitivity; the minor alleles of the polymorphisms N363 S and BclI are associated with relative hypersensitivity to GCs, while those of the polymorphisms ER22/23EK and 9β are associated with relative GC resistance. Because differences in GC sensitivity may influence immune effector functions, we examined whether these polymorphisms are associated with the susceptibility to develop Rheumatoid Arthritis (RA) and RA disease severity.

Methods

The presence of GR polymorphisms was assessed in healthy controls (n = 5033), and in RA patients (n = 368). A second control group (n = 532) was used for confirmation of results. In RA patients, the relationship between GR polymorphisms and disease severity was examined.

Results

Carriers of the N363 S and BclI minor alleles had a lower risk of developing RA: odds ratio (OR) = 0.55 (95% confidence interval (CI) 0.32-0.96, P = 0.032) and OR = 0.73 (95% CI 0.58-0.91, P = 0.006), respectively. In contrast, 9β minor allele carriers had a higher risk of developing RA: OR = 1.26 (95% CI 1.00-1.60, P = 0.050). For ER22/23EK minor allele carriers a trend to an increased risk OR = 1.42 (95% CI 0.95-2.13, P = 0.086) was found. All ER22/23EK carriers (32/32) had erosive disease, while only 77% (259/336) of the non-carriers did (P = 0.008). In addition, ER22/23EK carriers were treated more frequently with anti-tumor necrosis factor-alpha (TNFα) therapy (P < 0.05).

Conclusions

The minor alleles of the 9β and ER22/23EK polymorphisms seem to be associated with increased predisposition to develop RA. Conversely, the minor alleles of the N363 S and BclI polymorphisms are associated with reduced susceptibility to develop RA. These opposite associations suggest that constitutionally determined GC resistance may predispose to development of auto-immunity, at least in RA, and vice versa.

Expression in Hematological Malignancies of a Glucocorticoid Receptor Splice Variant That Augments Glucocorticoid Receptor-mediated Effects in Transfected Cells

Glucocorticoids play an important role in the treatment of a number of hematological malignancies, such as multiple myeloma. The effects of glucocorticoids are mediated through the glucocorticoid receptor α, the abundance of which can be modulated by alternative splicing of the glucocorticoid receptor mRNA. Two splice variants of the glucocorticoid receptor mRNA have been described: glucocorticoid receptor β, which reportedly has a dominant negative effect on the actions of the glucocorticoid receptor α, and glucocorticoid receptor P, of which the effects are unknown. In this study, we have investigated the expression levels of these two splice variants at the mRNA level in multiple myeloma cells and in a number of other hematological tumors. Although the glucocorticoid receptor β mRNA was, if at all, expressed at very low levels, considerable amounts (up to 50% of the total glucocorticoid receptor mRNA) glucocorticoid receptor P mRNA was present in most hematological malignancies. In transient transfection studies in several cell types and in multiple myeloma cell lines, the glucocorticoid receptor P increased the activity of the glucocorticoid receptor α. These results suggest that the relative levels of the glucocorticoid receptor α and the glucocorticoid receptor P may play a role in the occurrence of glucocorticoid resistance in tumor cells during the treatment of hematological malignancies with glucocorticoids.