Growth hormone (GH) and insulin-like growth factor-I (IGF-I) exert physiological actions on the skeleton throughout life, by stimulating longitudinal bone growth in children, the acquisition of bone mass during adolescence and the maintenance of skeletal architecture in adults. When GH and IGF-I are secreted in excess, bone remodeling is enhanced leading to deterioration of bone microstructure and impairment of bone strength. Indeed, acromegaly causes skeletal fragility, and vertebral fractures are reported in a remarkable number of subjects exposed to GH and IGF-I excess. The management of skeletal fragility in acromegaly is a challenge, since the awareness of this complication is low, the prediction of fracture risk is difficult to ascertain, the risk of fractures remains after the control of acromegaly and the effectiveness of bone-active drugs is unknown. This review is an update on bone disorders associated with acromegaly and provides a perspective of possible therapeutic approaches based on emerging pathophysiological and clinical information.
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- Author: Andrea G Lania x
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Gherardo Mazziotti, Andrea G A Lania, and Ernesto Canalis
Cristina L Ronchi, Elisa Verrua, Emanuele Ferrante, Gwendolyn Bender, Elisa Sala, Andrea G Lania, Martin Fassnacht, Paolo Beck-Peccoz, Bruno Allolio, Anna Spada, and Maura Arosio
Objective
Radiation therapy (RT) is a useful adjuvant tool for acromegalic patients not cured by surgery and/or not responding to pharmacotherapy. However, its specific effects on cardio- and cerebrovascular morbidity are still on debate.
Design
Retrospective analysis of 42 acromegalic patients cured after conventional radiotherapy (CRT, n=31) or radiosurgery by gamma-knife (GKRS, n=11) followed for a median period of 16.5 years (range: 2–40). Totally, 56 patients cured by surgery alone, with similar GH/IGF1 levels and duration of disease remission, served as control group.
Methods
Changes in cardiovascular risk factors, such as body mass index, glucose metabolism, insulin resistance, blood pressure, and lipid profile (pre-defined primary end point) and occurrence of new major cardio- and cerebrovascular events (secondary end point) during follow-up.
Results
The number of obese, hypertensive, and dyslipidemic subjects increased over time only in patients cured with RT. In contrast, the glucose response to the oral glucose tolerance test and the percentage of subjects with glucose alterations improved only in controls. As expected, the percentage of patients with pituitary failure was deeply higher among RT patients than among controls (86 vs 30%, P<0.0005). Despite these findings, a similar number of RT patients and controls developed major cardio- or cerebrovascular events (4/42 vs 3/56, P: NS). No differences were found between CRT and GKRS subgroups.
Conclusions
Previous RT seems to be associated with a worse metabolic profile in acromegalic patients studied after a long-term follow-up. Nevertheless, a direct link between RT and cardiovascular events remains to be proven.
Cristina L Ronchi, Erica Rizzo, Andrea G Lania, Rosario Pivonello, Silvia Grottoli, Annamaria Colao, Ezio Ghigo, Anna Spada, Maura Arosio, and Paolo Beck-Peccoz
Objective
It is still unknown whether prolonged treatment with somatostatin analogs (SSTa) may cause a long-lasting disease remission in GH-secreting adenomas after drug discontinuation. The aim of the present study was to investigate the evolution of GH/IGF-I secretion and tumor mass after SSTa withdrawal in patients affected by acromegaly.
Patients and Design
A total of 27 patients with acromegaly (12 de novo and 15 previously operated) were treated with SSTa for a median period of 48 months and considered optimally controlled in hormonal and neuroradiological terms. None of them were previously irradiated.
Methods
Basal GH, post-glucose GH nadir, IGF-I, clinical signs/symptoms, and metabolic parameters were evaluated after 12–16 weeks from drug withdrawal. Only patients who met the current criteria for disease remission remained in drug suspension being periodically re-evaluated for biochemical/clinical data and neuroradiological imaging.
Results
After 12–16 weeks withdrawal, 15 of the 27 patients had disease relapse and restarted SSTa, while 12 were considered ‘in disease remission’ (44% of total). Glucose metabolism improved in both euglycemic and diabetic patients after short-term SSTa discontinuation. Only one of the ten patients who reached 24 weeks withdrawal showed biochemical disease recurrence. On the whole, five of the patients still in remission after 6 months have already prolonged the follow-up over 12 months (median: 24 months), without clinical and biochemical/neuroradiological evidence of disease recurrence.
Conclusions
These preliminary data indicate a successful withdrawal of SSTa at least in a subset of well-responsive patients with acromegaly and challenge the previously held concept that medical therapy is always a lifelong requirement.
Claudia Giavoli, Emanuele Ferrante, Eriselda Profka, Luca Olgiati, Silvia Bergamaschi, Cristina L Ronchi, Elisa Verrua, Marcello Filopanti, Elena Passeri, Laura Montefusco, Andrea G Lania, Sabrina Corbetta, Maura Arosio, Bruno Ambrosi, Anna Spada, and Paolo Beck-Peccoz
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.
Cristina L Ronchi, Erika Peverelli, Sabine Herterich, Isabel Weigand, Giovanna Mantovani, Thomas Schwarzmayr, Silviu Sbiera, Bruno Allolio, Jürgen Honegger, Silke Appenzeller, Andrea G Lania, Martin Reincke, Davide Calebiro, Anna Spada, Michael Buchfelder, Joerg Flitsch, Tim M Strom, and Martin Fassnacht
Context
Alterations in the cAMP signaling pathway are common in hormonally active endocrine tumors. Somatic mutations at GNAS are causative in 30–40% of GH-secreting adenomas. Recently, mutations affecting the USP8 and PRKACA gene have been reported in ACTH-secreting pituitary adenomas and cortisol-secreting adrenocortical adenomas respectively. However, the pathogenesis of many GH-secreting adenomas remains unclear.
Aim
Comprehensive genetic characterization of sporadic GH-secreting adenomas and identification of new driver mutations.
Design
Screening for somatic mutations was performed in 67 GH-secreting adenomas by targeted sequencing for GNAS, PRKACA, and USP8 mutations (n=31) and next-generation exome sequencing (n=36).
Results
By targeted sequencing, known activating mutations in GNAS were detected in five cases (16.1%), while no somatic mutations were observed in both PRKACA and USP8. Whole-exome sequencing identified 132 protein-altering somatic mutations in 31/36 tumors with a median of three mutations per sample (range: 1–13). The only recurrent mutations have been observed in GNAS (31.4% of cases). However, seven genes involved in cAMP signaling pathway were affected in 14 of 36 samples and eight samples harbored variants in genes involved in the calcium signaling or metabolism. At the enrichment analysis, several altered genes resulted to be associated with developmental processes. No significant correlation between genetic alterations and the clinical data was observed.
Conclusion
This study provides a comprehensive analysis of somatic mutations in a large series of GH-secreting adenomas. No novel recurrent genetic alterations have been observed, but the data suggest that beside cAMP pathway, calcium signaling might be involved in the pathogenesis of these tumors.