Differential gene expression profiles of POMC-related enzymes, transcription factors and receptors between non-pituitary and pituitary ACTH-secreting tumors.
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The differential gene expression of proopiomelanocortin (POMC)-related processing enzymes, transcription factors, and receptors responsible for ACTH secretion between non-pituitary and pituitary ACTH-secreting tumors remains obscure. This study was attempted to determine the gene expression profiles of transcription factors (Tpit, NeuroD1 and IKZF1), proprotein convertase (PC) 1/3 and PC2, and several key receptors linked to ACTH secretion, including corticotrophin releasing hormone receptor (CRHR1), vasopressin receptor 1b (V1bR), somatostatin receptor (SSTR) subtype-2, -5 and dopamine receptor type 2 (D2R) in non-pituitary and pituitary ACTH-secreting tumors. Surgical tissue specimens from carcinoid tumors causing ectopic ACTH syndrome (EAS: n=4) and pituitary tumors causing Cushing's disease (CD: n=13), were subjected to real-time RT-PCR for measurements of each mRNA levels. POMC and CRHR1 mRNA levels in CD were far greater than those in EAS, whereas IKZF1, PC2, SSTR-2 and -5 mRNA levels in EAS were significantly greater than those in CD. NeuroD1, Tpit, PC1/3, V1bR and D2R mRNA levels were comparable between EAS and CD. In conclusion, differential gene expression profiles revealed more abundant mRNA expression in EAS than in CD of 1) IKZF1 with its potential implication of cell differentiation and hormone secretion, 2) PC2 with its possible enhanced processing activity of mature ACTH, and 3) SSTR-2 and -5 with their potential therapeutic application of more selective agonists in EAS patients. (+info)
Cushing syndrome secondary to ectopic adrenocorticotropic hormone secretion: the University of Texas MD Anderson Cancer Center Experience.
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Ectopic ACTH syndrome associated with large cell neuroendocrine carcinoma of the thymus.
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A 38-year-old man was admitted for evaluation of Cushing's syndrome. Physical findings showed swelling of the face, and hypertension, but not Cushingoid stigmata. Laboratory data revealed serum cortisol level of 34.1 microg/dL and plasma ACTH of 140 pg/mL. Overnight administration of 1 and 8 mg dexamethasone did not suppress plasma ACTH or serum cortisol. Chest X-ray showed a mass at the upper-anterior quadrant of the mediastinum, and chest CT scan revealed a heterogenous tumor of approximately 60 mm in diameter, which infiltrated into the superior vena cava and ascending aorta, and caused superior vena cava syndrome. The tumor was resected. Histological examination indicated large cell neuroendocrine carcinoma of the thymus and positive immunoreactivity for ACTH. Ten days after the operation, the plasma ACTH decreased as low as 13.7 pg/mL. The present study indicates that large cell neuroendocrine carcinoma of the thymus can cause superior vena cava syndrome and ectopic ACTH syndrome. (+info)
Prolactin as a marker of successful catheterization during IPSS in patients with ACTH-dependent Cushing's syndrome.
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Mifepristone effects on tumor somatostatin receptor expression in two patients with Cushing's syndrome due to ectopic adrenocorticotropin secretion.
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Pituitary cyclic Cushing's syndrome concomitant with solitary cryptococcal pneumonia confused with ectopic ACTH-producing tumor.
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A 47-year-old man with Cushingoid appearance was admitted to our hospital showing excessive secretion of cortisol at intervals of a few days. Cyclic Cushing's disease was confirmed. Two years earlier, results of hormonal assessment had been within normal limits and macroadenoma had been incidentally detected in the pituitary. Dexamethasone suppression testing revealed various responses and a small lung tumor was detected, therefore his condition was misinterpreted as ectopic ACTH-producing tumor or pituitary cyclical Cushing's disease, leading to lung resection that confirmed cryptococcal pneumonia. The pituitary tumor was finally identified as the cause of cyclic Cushing's syndrome and fully removed, allowing remission. (+info)