Allelic Variants of ARMC5 in Patients With Adrenal Incidentalomas and in Patients With Cushing's Syndrome Associated With Bilateral Adrenal Nodules.

Objective: Germline ARMC5 mutations are considered to be the main genetic cause of primary macronodular adrenal hyperplasia (PMAH). PMAH is associated with high variability of cortisol secretion caused from subclinical hypercortisolism to overt Cushing's syndrome (CS), in general due to bilateral adrenal nodules and rarely could also be due to non-synchronic unilateral adrenal nodules. The frequency of adrenal incidentalomas (AI) associated with PMAH is unknown. This study evaluated germline allelic variants of ARMC5 in patients with bilateral and unilateral AI and in patients with overt CS associated with bilateral adrenal nodules. Methods: We performed a retrospective multicenter study involving 123 patients with AI (64 bilateral; 59 unilateral). We also analyzed 20 patients with ACTH pituitary independent overt CS associated with bilateral adrenal nodules. All patients underwent germline genotyping analysis of ARMC5; abdominal CT and were classified as normal, possible or autonomous cortisol secretion, according to the low doses of dexamethasone suppression test. Results: We identified only one pathogenic allelic variant among the patients with bilateral AI. We did not identify any pathogenic allelic variants of ARMC5 in patients with unilateral AI. Thirteen out of 20 patients (65%) with overt CS and bilateral adrenal nodules were carriers of pathogenic germline ARMC5 allelic variants, all previously described. The germline ARMC5 mutation was observed in only one patient with bilateral AI; it was associated with autonomous cortisol secretion and showed to be a familial form. Conclusion: The rarity of germline ARMC5 mutations in AI points to other molecular mechanisms involved in this common adrenal disorder and should be investigated. In contrast, patients with overt Cushing's syndrome and bilateral adrenal nodules had the presence of ARMC5 mutations that were with high prevalence and similar to the literature. Therefore, we recommend the genetic analysis of ARMC5 for patients with established Cushing's syndrome and bilateral adrenal nodules rather than patients with unilateral AI.

Activation of the dopamine receptor type-2 (DRD2) promoter by 9-cis retinoic acid in a cellular model of Cushing's disease mediates the inhibition of cell proliferation and ACTH secretion without a complete corticotroph-to-melanotroph transdifferentiation.

Cushing's disease (CD) is a rare condition in which hypercortisolemia is secondary to excessive ACTH release from a pituitary corticotroph adenoma. CD is associated with significant morbidity and mortality, and a safe therapy that effectively targets the pituitary tumor is still lacking. Retinoic acid (RA) and dopamine agonists (DAs) have recently been considered as monotherapy in CD patients, and satisfactory results have been reported, albeit in a limited number of patients. Given the permissive role of RA on the dopamine receptor type-2 (DRD2), the aim of the present study was to see whether a combination of 9-cis RA and the DA bromocriptine (Br) might represent a possible treatment for CD. Here we show that 9-cis RA induces a functional DRD2 in the pituitary corticotroph cell line AtT20, and increases cell sensitivity to Br via a mechanism only partially related to corticotroph-to-melanotroph transdifferentiation. In addition, 9-cis RA and Br act synergistically to modulate cell viability, with favorable implications for clinical use. In nearly 45% of corticotropinoma-derived primary cultures, the combined administration of 9-cis RA and Br lowered the steady-state level of the ACTH precursor proopiomelanocortin (POMC) more efficiently than either of the drugs alone. In conclusion, the effects of a combination of 9-cis RA and Br on ACTH synthesis/secretion and cell viability in AtT20, and on POMC transcriptional activity in human corticotropinomas might represent a suitable starting point for assessing the potential of this treatment regimen for ACTH-secreting pituitary adenomas. This study thus has potentially important implications for novel therapeutic approaches to CD.

Cyclic Cushing's syndrome: an overview: [review]

Cyclic Cushing's syndrome (CS) is a disorder in which glucocorticoid levels are alternately normal and high, the latter occurring in episodes that can last from a few days to several months. It is more common in children than in adults. Cyclic CS may be either of the two different forms of CS (ACTH-dependent or -independent CS). Clinically, it may present with one or many symptoms, depending on the duration of disease activity and the timing of the fluctuations. A serotoninergic influence, cyclic changes in central dopaminergic tone, spontaneous episodic hemorrhage in the tumor, and the action of inflammatory cytokines with antitumor properties are some of the mechanisms suggested to explain the physiopathology of this phenomenon but the exact mechanism remains to be clarified. The cyclic pattern of hypercortisolism can delay the final diagnosis of CS and make it difficult to interpret the results of dynamic tests. Patients may have paradoxical responses to dexamethasone that can reflect increasing or decreasing levels of endogenous activity. Hormone assessments have to be repeated periodically when a diagnosis of CS is suspected. The cyclic pattern can also interfere with medical treatment because patients may show unexpected clinical and biochemical signs of hypocortisolism when cortisol secretion cyclically returns to normal, so an accurate follow-up is mandatory in these patients.

A síndrome de Cushing (SC) cíclica é uma doença na qual os níveis de glicocorticóides são alternadamente normais e elevados, os últimos ocorrendo em episódios que podem durar de poucos dias a vários meses. É mais comum em crianças do que em adultos. SC cíclica pode se manifestar como uma das duas diferentes formas de SC (ACTH-dependente ou independente). Clinicamente, ela pode se apresentar com um ou muitos sintomas, dependendo da duração da atividade da doença e do tempo das flutuações. Influência serotoninérgica, alterações cíclicas no tônus dopaminérgico central, hemorragia tumoral episódica espontânea e ação de citoquinas com propriedades antitumorais são alguns dos mecanismos sugeridos para explicar a fisiopatologia desse fenômeno, mas o mecanismo exato permanece obscuro. O padrão cíclico do hipercortisolismo pode atrasar o diagnóstico final da SC e tornar difícil a interpretação dos resultados dos testes dinâmicos. Alguns pacientes podem ter resposta paradoxal à dexametasona, que pode refletir níveis crescentes ou decrescentes da atividade endógena. A avaliação hormonal precisa ser repetida periodicamente quando há suspeita do diagnóstico de SC cíclica. O padrão cíclico pode também interferir com o tratamento médico, já que pacientes podem apresentar sinais clínicos e bioquímicos inesperados de hipocortisolismo quando a secreção de cortisol retorna ciclicamente ao normal, de modo que um acompanhamento acurado é obrigatório nesses pacientes.

Cyclic Cushing's syndrome: an overview.

Cyclic Cushing's syndrome (CS) is a disorder in which glucocorticoid levels are alternately normal and high, the latter occurring in episodes that can last from a few days to several months. It is more common in children than in adults. Cyclic CS may be either of the two different forms of CS (ACTH-dependent or -independent CS). Clinically, it may present with one or many symptoms, depending on the duration of disease activity and the timing of the fluctuations. A serotoninergic influence, cyclic changes in central dopaminergic tone, spontaneous episodic hemorrhage in the tumor, and the action of inflammatory cytokines with antitumor properties are some of the mechanisms suggested to explain the physiopathology of this phenomenon but the exact mechanism remains to be clarified. The cyclic pattern of hypercortisolism can delay the final diagnosis of CS and make it difficult to interpret the results of dynamic tests. Patients may have paradoxical responses to dexamethasone that can reflect increasing or decreasing levels of endogenous activity. Hormone assessments have to be repeated periodically when a diagnosis of CS is suspected. The cyclic pattern can also interfere with medical treatment because patients may show unexpected clinical and biochemical signs of hypocortisolism when cortisol secretion cyclically returns to normal, so an accurate follow-up is mandatory in these patients.