An activating mutation in the CRHR1 gene is rarely associated with pituitary-dependent hyperadrenocorticism in poodles

OBJECTIVES: Pituitary-dependent hyperadrenocorticism is the most common cause of naturally occurring hypercortisolism in dogs. CRHR1 expression in human and dog corticotrophinomas suggested that this gene affects pituitary tumorigenesis. The present study aimed to investigate mutations in the CRHR1 coding region in poodles with pituitary-dependent hyperadrenocorticism. METHODS: Fifty poodles with pituitary-dependent hyperadrenocorticism and 50 healthy poodles were studied. Genomic DNA was amplified by PCR and analyzed by Sanger sequencing. RESULTS: The novel CRHR1 p.V97M mutation was identified in one dog. This valine residue, located in the amino-terminal extracellular domain, exhibits high affinity for its corticotropin-releasing hormone (CRH) ligand. Bioinformatic analysis revealed structural rearrangements in the mutant protein, with a 17% increase in the surface binding affinity between CRHR1 and CRH. In vitro functional studies showed that mutant CRHR1 induced higher ACTH secretion than the wild type after stimulation with human CRH. CONCLUSION: These results suggest that germline activating mutations in CRHR1 may be a rare cause of pituitary hyperadrenocorticism in poodles.

Modulatory effect of BclI GR gene polymorphisms on the obesity phenotype in Brazilian patients with Cushing's disease

OBJECTIVES: Patients with Cushing's disease exhibit wide phenotypic variability in the severity of obesity, diabetes and hypertension. In the general population, several glucocorticoid receptor genes (NR3C1) and HSD11B1 polymorphisms are associated with altered glucocorticoid sensitivity and/or metabolism, resulting in an increased or reduced risk of an adverse metabolic profile. Our aim was to analyze the association of NR3C1 and HSD11B1 gene variants with the severity of some clinical and hormonal features of Cushing's disease. METHODS: Sixty-four patients presenting with Cushing's disease were diagnosed based on adrenocorticotrophic hormone levels, high-dose dexamethasone suppression tests and/or inferior petrosal sinus sampling and magnetic resonance imaging. The A3669G, ER22/23EK, N363S BclI-NR3C1 and HSD11B1-rs12086634 variants were screened. RESULTS: The BclI, HSD11B1-rs12086634 and A3669G variants were found in 36%, 19.5% and 14% of alleles, respectively. The N363S and ER22/23EK polymorphisms were identified in heterozygosis once in only two patients (1.5% of alleles). There were no differences in the weight gain or prevalence of diabetes and hypertension in the patients carrying the abovementioned alleles compared to the wild-type carriers. Interestingly, the mean body mass index (BMI) of the BclI carriers was significantly higher than the non-carriers (34.4±7 kg/m2 vs. 29.6±4.7 kg/m2, respectively). None of the polymorphisms were associated with the basal adrenocorticotrophic hormone, FU levels or F level after dexamethasone suppression testing. CONCLUSION: Although Cushing's disease results from increased glucocorticoid secretion, we observed that interindividual variability in the peripheral glucocorticoid sensitivity, mediated by the glucocorticoid receptor, could modulate the obesity phenotype. .

Application of genetic testing to define the surgical approach in a sporadic case of multiple endocrine neoplasia type 1 / Aplicação de teste genético para definição da conduta cirúrgica num caso esporádico de neoplasia endócrina múltipla do tipo 1

We report the use of a genetic test for therapeutic decision making in a case of primary hyperparathyroidism associated with Cushing's disease (CD). A 20-year-old woman was evaluated for gradual weight gain, asthenia, muscle pain, and hypertension. Biochemical and radiologic tests confirmed CD and she underwent transsphenoidal surgery. Immunohistochemistry of the microadenoma was positive for adrenocorticotropic hormone (ACTH). On follow-up, hypercalcemia with high parathyroid hormone (PTH) levels was detected, associated with nephrolithiasis and low bone mineral density in the spine and hip. Parathyroid scintigraphy showed tracer uptake in the inferior region of the left thyroid lobe, and cervical ultrasound showed a heterogeneous nodule in the same area, suggestive of a parathyroid adenoma (PA). Genetic testing detected mutation in the MEN 1 gene and total parathyroidectomy with the implantation of a fragment of one gland in the forearm was performed. Pathology showed a PA and 3 normal parathyroid glands, without hyperplasia, despite the diagnosis of MEN 1. This case illustrates the role of genetic testing in defining the therapeutic approach for sporadic MEN 1.

Relatamos o uso de teste genético para decisão terapêutica em um caso de hiperparatireoidismo primário associado com doença de Cushing (DC). Uma jovem de 20 anos foi avaliada por ganho de peso gradual, astenia, mialgias e hipertensão. Os exames complementares confirmaram DC e ela foi submetida à cirurgia transesfenoidal. A análise imuno-histoquímica do microadenoma foi positiva para hormônio adrenocorticotrófico (ACTH). No seguimento, a paciente apresentou hipercalcemia com níveis elevados de hormônio de paratireoide (PTH), nefrolitíase e densidade mineral óssea baixa em coluna e fêmur. A cintilografia de paratireoide mostrou captação do traçador em região inferior do lobo esquerdo da tireoide e a ecografia cervical revelou nódulo heterogêneo na mesma área, sugestivo de adenoma da paratireoide (AP). O teste genético detectou mutação no gene MEN 1 e ela foi submetida à paratireoidectomia total com implante de fragmento de uma das glândulas no antebraço. A patologia confirmou AP e as outras três glândulas normais, sem hiperplasia, apesar do diagnóstico de MEN 1. Esse caso ilustra a importância do teste genético para definir a abordagem terapêutica em um caso esporádico de MEN 1.

Papel da via lkaros-FGFR4 na evolução pós-cirúrgica dos pacientes com Doença de Cushing / Ikaros-FGFR4 pathway role in the postoperative outcome of Cushing's Disease

Os mecanismos envolvidos na patogênese molecular dos tumores hipofisários corticotróficos são complexos, heterogêneos e permanecem na maioria dos casos desconhecidos. Alterações da expressão de componentes da via Ikaros (Ik), tais como do receptor 4 dos fatores de crescimento de fibroblastos (FGFR4) têm sido detectadas em tumores hipofisários, inclusive nos corticotropinomas. O desbalanço entre as isoformas longas e curtas do Ikaros resulta em um início de transcrição alternativa do FGFR4, codificando uma isoforma truncada do gene (pdt- FGFR4) que foi associada a tumores hipofisários maiores e mais invasivos. A isoforma curta Ik6 promove a expressão do fator anti-apoptótico Bcl-XL in vitro, um efeito independente da interação com as isoformas longas. Além disso, um polimorfismo do FGFR4, com substituição da glicina por arginina no códon 388 (G388R), tem sido associado à evolução desfavorável em vários tipos tumorais humanos. Objetivos: Analisar a expressão do Bcl-XL, das isoformas do Ikaros (Ik1+Ik2/Ik total) e do FGFR4 em corticotropinomas humanos. Avaliar a freqüência dos genótipos do códon 388 do FGFR4 nos pacientes com doença de Cushing e sua associação com a evolução pósoperatória após a primeira cirurgia transesfenoidal. Métodos: Noventa e sete pacientes com diagnóstico de doença de Cushing foram estudados. Os dados clínicos, hormonais e histopatológicos foram avaliados retrospectivamente. O estudo da expressão do Bcl-XL, do Ikaros, e do FGFR4 foi realizado por PCR em tempo real em 20 amostras de corticotropinomas, sendo dois tumores correspondentes à síndrome de Nelson. A determinação dos genótipos no códon 388 do FGFR4 foi realizada nos 97 pacientes e em 103 indivíduos controles, por PCR de fragmento do exon 9 do gene FGFR4 seguida de digestão com a enzima de restrição BstNI. A evolução pós-operatória (remissão/recidiva) da doença de Cushing foi avaliada em 76 pacientes. Foram considerados em remissão aqueles pacientes com níveis normais...

The mechanisms involved in the molecular pathogenesis of corticotroph pituitary tumors are complex, heterogeneous and in most cases remain unknown. Changes in the expression of components of Ikaros (Ik) pathway, such as receptor 4 of fibroblast growth factor (FGFR4), have been detected in pituitary tumors including corticotropinomas. Imbalance between long and short Ik isoforms results in alternative transcription initiation of FGFR4 and encodes a truncated isoform of the gene (pdt-FGFR4) which was associated with larger and more invasive pituitary tumors. The Ik6 short isoform promotes Bcl-XL expression in vitro, an effect independent of the interaction with the long isoforms. In addition, a polymorphism of FGFR4 gene, the substitution of glycine by arginine at codon 388 (G388R), has been associated with adverse outcome in several human tumor types. Objectives: To analyze the expression of Bcl-XL, Ikaros isoforms (Ik1 + Ik2/Ikaros total), and FGFR4 in human corticotropinomas. To determine the frequency of each genotype at codon 388 of FGFR4 in patients with Cushing's disease and its association with the postoperative outcome after the first transsphenoidal surgery. Methods: Ninety-seven patients with Cushing's disease were evaluated. Clinical, hormonal and histopathological findings were assessed retrospectively. The expression of Bcl-XL, Ikaros and FGFR4 were evaluated by real-time PCR in 20 samples of corticotropinomas, including two samples of Nelson's syndrome. The FGFR4 genotype was determined in the 97 patients and 103 control subjects by PCR fragment of exon 9 of the FGFR4 gene, followed by digestion with the BstNI restriction enzyme. The postoperative outcome (remission/relapse) of Cushing's disease was assessed in 76 patients. The patients with normal urinary cortisol levels during the first year after surgery, in the absence of hormone replacement therapy, and those who...

Analysis of glucose-dependent insulinotropic peptide receptor (GIPR) and luteinizing hormone receptor (LHCGR) expression in human adrenocortical hyperplasia / Análise da expressão dos receptores do peptídeo insulinotrópico dependente de glicose (GIPR) e do hormônio luteinizante (LHCGR) nas hiperplasias adrenocorticais humanas

OBJECTIVE: To analyze the aberrant expression of the GIPR and LHCGR in different forms of adrenocortical hyperplasia: ACTH-independent macronodular adrenal hyperplasia (AIMAH), primary pigmented nodular adrenocortical disease (PPNAD) and diffuse adrenal hyperplasia secondary to Cushing's disease (DAHCD). METHODS: We quantified GIPR and LHCGR expressions using real time PCR in 20 patients with adrenocortical hyperplasia (seven with AIMAH, five with PPNAD, and eight with DAHCD). Normal adrenals tissues were used as control and the relative expression was compared with β-actin. RESULTS: GIPR and LHCGR expressions were demonstrated in all tissues studied. Median GIPR and LHCGR mRNA levels were 1.6; 0.4; 0.5 and 1.3; 0.9; 1.0 in adrenocortical tissues from AIMAH, PPNAD and DAHCD respectively. There were no differences between GIPR and LHCGR expressions in all tissues studied. CONCLUSIONS: GIPR and LHCGR overexpression were not identified in the studied cases, thus suggesting that this molecular mechanism is not involved in adrenocortical hyperplasia in our patients.

OBJETIVO: Analisar a expressão aberrante do GIPR e do LHCGR em diferentes formas de hiperplasias adrenocorticais: hiperplasia adrenal macronodular independente de ACTH (AIMAH), doença adrenocortical nodular pigmentada primária (PPNAD) e hiperplasia adrenal difusa secundária à doença de Cushing (DAHCD). MÉTODOS: Quantificou-se por PCR em tempo real a expressão desses receptores em 20 pacientes: sete com AIMAH, cinco com PPNAD e oito com DAHCD. Adrenais normais foram utilizadas como controle e a expressão relativa desses receptores foi comparada à expressão da β-actina. RESULTADOS: A expressão desses receptores foi demonstrada em todos os tecidos estudados. A mediana da expressão do GIPR e do LHCGR foi de 1,6; 0,4; 0,5 e de 1,3; 0,9; 1,0 nos tecidos dos pacientes com AIMAH, PPNAD e DAHCD, respectivamente. Não houve diferença significativa na expressão desses receptores nos tecidos estudados. CONCLUSÕES: Hiperexpressão do GIPR e do LHCGR não foi observada, sugerindo que esse mecanismo não está envolvido na patogênese molecular da hiperplasia adrenal nesses pacientes.