Cushing's syndrome (CS) patients have increased mortality primarily due to cardiovascular events induced by glucocorticoid (GC) excess-related severe metabolic changes. Glucose metabolism abnormalities are common in CS due to increased gluconeogenesis, disruption of insulin signalling with reduced glucose uptake and disposal of glucose and altered insulin secretion, consequent to the combination of GCs effects on liver, muscle, adipose tissue and pancreas. Dyslipidaemia is a frequent feature in CS as a result of GC-induced increased lipolysis, lipid mobilisation, liponeogenesis and adipogenesis. Protein metabolism is severely affected by GC excess via complex direct and indirect stimulation of protein breakdown and inhibition of protein synthesis, which can lead to muscle loss. CS patients show changes in body composition, with fat redistribution resulting in accumulation of central adipose tissue. Metabolic changes, altered adipokine release, GC-induced heart and vasculature abnormalities, hypertension and atherosclerosis contribute to the increased cardiovascular morbidity and mortality. In paediatric CS patients, the interplay between GC and the GH/IGF1 axis affects growth and body composition, while in adults it further contributes to the metabolic derangement. GC excess has a myriad of deleterious effects and here we attempt to summarise the metabolic comorbidities related to CS and their management in the perspective of reducing the cardiovascular risk and mortality overall.
Francesco Ferraù and Márta Korbonits
Sarah J Larkin, Francesco Ferraù, Niki Karavitaki, Laura C Hernández-Ramírez, Olaf Ansorge, Ashley B Grossman, and Márta Korbonits
The pathogenetic mechanisms of sporadic somatotroph adenomas are not well understood, but derangements of the cAMP pathway have been implicated. Recent studies have identified L206R mutations in the alpha catalytic subunit of protein kinase A (PRKACA) in cortisol-producing adrenocortical adenomas and amplification of the beta catalytic subunit of protein kinase A PRKACB in acromegaly associated with Carney complex. Given that both adrenocortical adenomas and somatotroph adenomas are known to be reliant on the cAMP signalling pathway, we sought to determine the relevance of the L206R mutation in both PRKACA and PRKACB for the pathogenesis of sporadic somatotroph adenomas.
Somatotroph adenoma specimens, both frozen and formalin-fixed, from patients who underwent surgery for their acromegaly between 1995 and 2012, were used in the study.
The DNA sequence at codon 206 of PRKACA and PRKACB was determined by PCR amplification and sequencing. The results were compared with patient characteristics, the mutational status of the GNAS complex locus and the tumour granulation pattern.
No mutations at codon 206 of PRKACA or PRKACB were found in a total of 92 specimens, comprising both WT and mutant GNAS cases, and densely, sparsely and mixed granulation patterns.
It is unlikely that mutation at this locus is involved in the pathogenesis of sporadic somatotroph adenoma; however, gene amplification or mutations at other loci or in other components of the cAMP signalling pathway, while unlikely, cannot be ruled out.
Salvatore Crisafulli, Nicoletta Luxi, Janet Sultana, Andrea Fontana, Federica Spagnolo, Giuseppe Giuffrida, Francesco Ferrau, Daniele Gianfrilli, Alessia Cozzolino, Maria Cristina De Martino, Federico Gatto, Francesco Barone-Adesi, Salvatore Cannavò, and Gianluca Trifirò
Objective: To date, no systematic reviews and meta-analysis on the global epidemiology of acromegaly are available in literature. The aims of this study are to provide a systematic review and a meta-analysis of the global epidemiology of acromegaly and to evaluate the quality of study reporting for the identified studies.
Methods: MEDLINE, EMBASE and The Cochrane Library databases were searched for studies assessing the epidemiology of acromegaly from inception until 31st January 2020. We included original observational studies written in English, reporting acromegaly prevalence and/or incidence for a well-defined geographic area. Two reviewers independently extracted data and performed quality assessments. Prevalence and incidence pooled estimates were derived performing a random-effects meta-analysis.
Results: A total of 32 studies were included in the systematic review, and 22 of them were included in the meta-analysis. The pooled prevalence of acromegaly was 5.9 (95%CI: 4.4-7.9) per 100,000 persons, while the incidence rate (IR) was 0.38 (95%CI: 0.32-0.44) cases per 100,000 person-years. For both prevalence and IR, a considerable between-study heterogeneity was found (I2= 99.3% and 86.0%, respectively). The quality of study reporting was rated as medium for 20 studies and low for 12 studies.
Conclusions: Although the largest amount of heterogeneity was due to the high precision of the studies’ estimates, data source and geographic area could represent relevant study-levels factors which could explain about 50% of the total between-study variability. Large-scale high quality studies on the epidemiology of acromegaly are warranted to help the public health system in making decisions.
Luis G Pérez-Rivas, Marily Theodoropoulou, Troy H Puar, Julia Fazel, Mareike R Stieg, Francesco Ferraù, Guillaume Assié, Monica R Gadelha, Timo Deutschbein, Maria C Fragoso, Benno Kusters, Wolfgang Saeger, Jürgen Honegger, Michael Buchfelder, Márta Korbonits, Jérôme Bertherat, Günter K Stalla, Ad R Hermus, Felix Beuschlein, and Martin Reincke
Somatic mutations in the ubiquitin-specific protease 8 (USP8) gene are frequent in corticotroph tumors causing Cushing’s disease (CD). Corticotroph tumor progression, the so-called Nelson’s syndrome (NS), is a potentially life-threatening complication of bilateral adrenalectomy in patients with refractory CD that is caused by the development of an ACTH-secreting tumor of the pituitary gland. Whether USP8 alterations are also present in progressive Nelson’s tumors has not been studied in detail so far.
Design and Methods
Retrospective, multicenter study involving tumors from 33 patients with progressive corticotroph tumors (29 females) and screening for somatic mutations on the mutational hotspot of the USP8 gene in the exon 14 with Sanger sequencing.
Fifteen out of 33 tumors (45%) presented with a mutation in the exon 14 of USP8, with c.2159C>A (p.Pro720Gln) being the most frequent (9/33), followed by c.2155_2157delTCC (p.Ser718del, 4/33) and c.2152T>C (p.Ser718Pro, 2/33). This prevalence is similar to that previously reported for CD. Mutations were found exclusively in females. Other variables, such as age at diagnosis with NS, body mass index, hyperpigmentation, visual field defects, adenoma size or mortality, did not significantly differ between patients with wild-type and mutant tumors. Patients with USP8 mutant tumors exhibited higher levels of plasma ACTH after surgery (median: 640 vs 112 pg/mL, P = 0.03). No differences were observed in ACTH normalization (<50 pg/mL) and tumor control after surgery for Nelson’s tumor.
Somatic mutations in USP8 are common in Nelson’s tumors, indicating that they do not drive the corticotroph tumor progression that leads to NS, and may be associated with a less favorable biochemical outcome after surgery for Nelson’s tumor.