Luca Olgiati

Growth Hormone Receptor Variants and Response to Pegvisomant in Monotherapy or in Combination with Somatostatin Analogs in Acromegalic Patients: A Multicenter Study

CONTEXT The influence of full-length GH receptor (GHR) and exon 3-deleted GHR (d3GHR) on responsiveness to pegvisomant (PEG-V) in acromegalic patients is uncertain. OBJECTIVE The aim of the study was to assess the distribution of GHR genotypes in a large series of patients on PEG-V therapy and their influence on treatment efficacy and adverse effects. DESIGN AND SETTING A cross-sectional multicenter pharmacogenetic study was conducted in 16 Italian endocrinology centers of major universities and tertiary care hospitals. PATIENTS The study included 127 acromegalic patients enrolled from 2009 to 2010 not cured by previous surgery, radiotherapy, and long-acting somatostatin (SST) analogs, treated with PEG-V. INTERVENTION AND MAIN OUTCOME MEASURE Sixty-three of 127 patients received combined PEG-V + SST analog therapy. Clinical and hormonal data at diagnosis and before and during PEG-V therapy were inserted in a database. GHR exon 3 deletion and other polymorphisms were genotyped by the coordinator center. Differences in PEG-V dosage required for IGF-I normalization and occurrence of adverse effects between carriers and noncarriers of GHR variants were evaluated. RESULTS d3GHR variants were not in Hardy-Weinberg equilibrium (P = 0.008). No association of these variants with PEG-V dose required for IGF-I normalization, adverse effects occurrence, and tumor regrowth was found in patients on PEG-V and on PEG-V + SST analog treatment. Similar data were obtained considering the GHR variant rs6180. CONCLUSIONS This study did not confirm a better response of d3GHR to PEG-V treatment in acromegaly. Other studies are needed to determine whether deviation from Hardy-Weinberg equilibrium may indicate an association of d3GHR genotype with poor response to usual treatments.

Role of glucocorticoid receptor polymorphism in adrenal incidentalomas

Eur J Clin Invest 2010; 40 (9): 803–811

The dopamine–somatostatin chimeric compound BIM-23A760 exerts antiproliferative and cytotoxic effects in human non-functioning pituitary tumors by activating ERK1/2 and p38 pathways

The study investigated the effects of the dopamine-somatostatin chimeric compound BIM-23A760 on cell proliferation and apoptosis in cultured cells from human non-functioning pituitary tumors (NFPTs). Both BIM-23A760 and the dopaminergic agonist BIM-53097 induced a significant inhibition of cell proliferation associated with increased p27 expression, together with a significant increase in caspase-3 activity. Conversely, null or marginal effects were elicited by somatostatin analogs. Moreover, BIM-23A760 and BIM-53097 induced ERK1/2 and p38 phosphorylation and the blockade of these pathways prevented both the antiproliferative and the pro-apoptotic effects of these drugs. In conclusions the chimeric compound BIM-23A760 is able to exert cytostatic and cytotoxic effects in NFPTs, these phenomena being mainly mediated by DR2D and involving ERK1/2 and p38 pathways activation.

MEN1-related hyperparathyroidism: response to cinacalcet and its relationship with the calcium-sensing receptor gene variant Arg990Gly

OBJECTIVE Primary hyperparathyroidism (PHPT) is a challenging problem in type 1 multiple endocrine neoplasia (MEN1) due to the high postsurgery recurrence rate. The aim was to evaluate the efficacy of cinacalcet in MEN1 patients in comparison with patients with sporadic PHPT (sPHPT) and the effect of Arg990Gly calcium-sensing receptor (CASR) polymorphism on the response to treatment. DESIGN This is a randomized, crossover, double-blind study carried out in the University Hospitals. METHODS Fifteen MEN1 patients with PHPT were randomized to two groups, one administered with 30 mg daily cinacalcet, titrated until calcium normalization, and one with placebo. After 3 months, patients were reassessed and after washout switched to the other treatment. For comparison, 20 sPHPT patients with similar calcium levels were administered with cinacalcet for 3 months. Ionized and total calcium, phosphate, and parathyroid hormone (PTH) were evaluated. CASR Arg990Gly was genotyped on blood DNA by direct sequencing. RESULTS Cinacalcet normalized calcium, increased phosphate, and reduced PTH levels in all patients. Cinacalcet dosage required to normalize calcium in MEN1 and sPHPT was not significantly different (45±21 vs 54±25 mg/day). Few mild adverse events, not requiring drug withdrawal, were observed in both the groups. No association between Arg990Gly CASR polymorphism and response to cinacalcet was found. CONCLUSIONS This short-term prospective study demonstrated that the efficacy profile of cinacalcet in patients with MEN1-related PHPT and in those with sPHPT was similar and was not influenced by the 990 CASR variant. Although long-term safety and efficacy data are required, cinacalcet might be considered a treatment option in MEN1 patients who have contraindications to surgery or persistent PHPT after surgery.

d3-Growth hormone receptor polymorphism in acromegaly: effects on metabolic phenotype.

Objective  A common polymorphic variant of the growth hormone receptor (GHR) is because of genomic deletion of exon 3 and has been linked with increased responsiveness to exogenous GH. The impact of this polymorphism in acromegaly, a disease characterized by endogenous excess of GH and partial loss of IGF‐I feedback on tumoural GH secretion, is not clear. The aim of this study was to investigate possible influences of d3GHR on the GH/IGF‐I relationship and metabolic parameters in acromegaly.

The role of salivary cortisol measured by liquid chromatography–tandem mass spectrometry in the diagnosis of subclinical hypercortisolism

OBJECTIVE The use of late-night salivary cortisol (LNSalC) for diagnosing subclinical hypercortisolism (SH) is debated. No data are available regarding the role of LNSalC as measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in SH diagnosis. The aim of this study was to evaluate the diagnostic accuracy of LNSalC measured by LC-MS/MS in SH. DESIGN Cross-sectional prospective study of outpatients. METHODS In 70 consecutive patients with adrenal incidentalomas (AI), without signs and symptoms of hypercortisolism, we diagnosed SH in the presence of at least two of the following: cortisol after 1 mg overnight dexamethasone suppression test (1  mg DST) >83  nmol/l, 24-h urinary free cortisol (UFC) >193  nmol/24  h, and morning ACTH <2.2  pmol/l. The LNSalC levels by LC-MS/MS at 2300  h (normal values <2.8  nmol/l) and the presence of hypertension, type 2 diabetes mellitus (T2DM), and osteoporosis (OP) were assessed. RESULTS The increased LNSalC levels (>2.8  nmol/l) had an 83.3% specificity (SP) and a 31.3% sensitivity (SN) for predicting the biochemical diagnosis of SH. The increased LNSalC had an 85.2% SP and a 55.6% SN for predicting the presence of hypertension, T2DM, and OP, while the combination of LNSalC >1.4  nmol/l (cutoff with 100% SN) plus 1 mg DST >50  nmol/l had an 88.9% SN and an 85.2% SP (similar to SH criterion at enrollment). CONCLUSIONS In AI patients, LNSalC measured by LC-MS/MS appears to be useful in combination with 1 mg DST for diagnosing SH, while it is not useful as a single criterion.

Filamin-A Is Essential for Dopamine D2 Receptor Expression and Signaling in Tumorous Lactotrophs

CONTEXT Dopamine agonists (DA) are the first choice treatment of prolactinomas. However, a subset of patients is resistant to DA, due to undefined dopamine D2 receptor (D2R) alterations. Recently, D2R was found to associate with filamin-A (FLNA), a widely expressed cytoskeleton protein with scaffolding properties, in melanoma and neuronal cells. OBJECTIVE The aim of the study was to investigate the role of FLNA in D2R expression and signaling in human tumorous lactotrophs and rat MMQ and GH3 cells. DESIGN We analyzed FLNA expression in a series of prolactinomas by immunohistochemistry and Western blotting. We performed FLNA silencing or transfection experiments in cultured cells from DA-sensitive or -resistant prolactinomas and in MMQ and GH3 cells, followed by analysis of D2R expression and signaling. RESULTS We demonstrated reduced FLNA and D2R expression in DA-resistant tumors. The crucial role of FLNA on D2R was demonstrated by experiments showing that: 1) FLNA silencing in DA-sensitive prolactinomas resulted in 60% reduction of D2R expression and abrogation of DA-induced inhibition of prolactin release and antiproliferative signals, these results being replicated in MMQ cells that endogenously express FLNA and D2R; and 2) FLNA overexpression in DA-resistant prolactinomas restored D2R expression and prolactin responsiveness to DA, whereas this manipulation was ineffective in GH3 cells that express FLNA but not D2R. No alteration in FLNA promoter methylation was detected, ruling out the occurrence of epigenetic FLNA silencing in DA-resistant prolactinomas. CONCLUSIONS These data indicate that FLNA is crucial for D2R expression and signaling in lactotrophs, suggesting that the impaired response to DA may be related to the reduction of FLNA expression in DA-resistant prolactinomas.

Influence of the d3GH receptor polymorphism on the metabolic and biochemical phenotype of GH-deficient adults at baseline and during short- and long-term recombinant human GH replacement therapy

OBJECTIVE A common polymorphic variant of GH receptor (exon 3 deletion, d3GHR) has been linked with increased response to recombinant human GH (rhGH) in some patients with or without GH deficiency (GHD). The aim of the study was to investigate the impact of the GHR genotype on the phenotype of GHD adults and on the metabolic effect of rhGH therapy. DESIGN Prospective study of GHD patients evaluated before and during short- (1 year, n=100) and long-term (5 years, n=50) rhGH therapy. METHODS Effects of rhGH on IGF1 levels, body composition (body fat percentage, BF%), body mass index, lipid profile, and glucose homeostasis (fasting insulin and glucose, insulin sensitivity indexes) were evaluated according to the presence or the absence of the d3GHR variant. RESULTS The different genotype did not influence basal phenotype of GHD. Short-term rhGH determined normalization of IGF1 levels, decrease in BF%, and worsening of insulin sensitivity, independently from the presence of the d3GHR allele. A significant increase in high-density lipoprotein cholesterol occurred in the d3GHR group. Normalization of IGF1 levels and decrease in BF% were maintained after 5 years. Insulin sensitivity restored to basal values, though in d3GHR patients fasting glucose remained significantly higher than at baseline. After both 1 and 5 years, percentage of subjects with impaired glucose tolerance, similar in the two groups at baseline, decreased in fl/fl while doubled in d3GHR patients. In this last group, a long-term significant reduction in total and low-density lipoprotein cholesterol was also observed. CONCLUSION The functional difference of d3GHR may influence some metabolic effects of rhGH on GHD adults.

Effect of 9-cis Retinoic Acid on Dopamine D2 Receptor Expression in Pituitary Adenoma Cells

The dopamine receptor subtype 2 (D2R) promoter contains a functional retinoic acid response element involved in the control of D2R expression. The aim of the study was to evaluate the effect of 9-cis retinoic acid (9-cis RA) on D2R protein expression in human pituitary adenomas and GH3 cell line. Treatment with 9-cis RA (100 nM for 48 hrs) caused a 109 ± 32% increase of basal D2R levels in five of eight growth hormone (GH)-secreting adenomas (GH-omas), a 129 ± 28% increase in 7 of 11 nonfunctioning adenomas, and no effect in two resistant prolactinomas by Western blotting. The lack of D2R induction in some tumors was not associated with a different pattern of retinoid x receptor (RXR) and retinoic acid receptor (RAR) isoform expression that was similar in all tumors by immunohistochemistry. While the induction of D2R did not affect the slight but significant inhibitory effect exerted by dopamine (10 nM) on in vitro GH release by GH-oma cultured cells, in pituitary GH3 cell lines cis-9 RA enhanced the dopamine-induced inhibition of in vitro GH release (% inhibition: 16 ± 2 versus 26 ± 5, P < 0.05), cell proliferation (25 ± 2% versus 44 ± 5%, P < 0.05) and cell viability (16 ± 0.8% versus 29 ± 1%, P < 0.05), likely by activating caspase-3 (28 ± 3% versus basal, P < 0.05). In conclusion, this study provides novel evidence for a permissive role of retinoids on the expression of D2R in a good proportion of pituitary tumors and on the generation of pro-apoptotic signals in GH3 cell line.

GH Response to Oral Glucose Tolerance Test: A Comparison between Patients with Acromegaly and Other Pituitary Disorders

CONTEXT The cutoff value of nadir GH after an oral glucose tolerance test (OGTT) used to define disease remission in acromegaly is higher than that observed in healthy subjects. However, it is uncertain whether the impaired GH inhibition might be related to subtle abnormalities of GH secretion or to functional and/or anatomical hypothalamic-pituitary disconnection due to tumor per se or treatments. OBJECTIVE The objective of the study was to evaluate the impact of pituitary disorders other than acromegaly on GH response to OGTT. DESIGN, SUBJECTS, AND METHODS: Thirty-three patients (24 females and nine males, aged 50.1 ± 12.3 yr, 13 operated and two irradiated) with various hypothalamic-pituitary disorders (HPDs), 45 healthy subjects (controls), and 42 cured acromegalic patients matched for sex, age. and body mass index were investigated. All subjects were studied for IGF-I levels and GH levels before and during the OGTT. RESULTS In HPD patients mean postglucose nadir GH levels were 0.11 ± 0.08 μg/liter without any difference between patients treated with neurosurgery and/or radiotherapy and untreated and between patients with and without pituitary stalk alterations and/or hyperprolactinemia. Mean nadir GH values were similar in HPD patients and controls (0.11 ± 0.08 vs. 0.08 ± 0.08 μg/liter, P = 0.23) and lower than those found in cured acromegalic patients (0.18 ± 0.13 μg/liter, P = 0.02), although there was an overlapping in about half of patients. CONCLUSIONS Hypothalamic control of glucose-mediated GH suppression is not perturbed in patients with HPD. These data indicate that defective GH suppression to glucose that is found in acromegaly is unlikely to reflect a lack of integrity of hypothalamic function.