Presence of corticotropin-releasing factor-like immunoreactivity in human tumors

The corticotropin releasing factor system in cancer: expression and pathophysiological implications

Malignant tumors express multiple factors that have some role in the regulating networks supporting their ectopic growth. Recently, increased interest has been developing in the expression and biological role of the neuropeptides and receptors of the corticotropin releasing factor (CRF) system, the principal neuroendocrine mediator of the stress response, especially in the light of several R&D programs for small molecule antagonists that could present some anticancer therapeutic benefit. In the present article, we review the literature suggesting that the CRF system could be involved in the regulation of human cancer development. Potential implication in growth, metastasis, angiogenesis, or immune parameters via activation of locally expressed receptors could be clinically exploited by presenting targets of new therapeutic approaches.

Corticotropin-releasing hormone and its structurally related urocortin are synthesized and secreted by human mast cells

Stress activates the hypothalamic-pituitary-adrenal axis through CRH, leading to production of glucocorticoids that down-regulate immune responses. However, acute stress also has proinflammatory effects. We previously showed that restraint stress, as well as CRH and its structurally related urocortin (Ucn), could activate mast cells and trigger mast cell-dependent vascular permeability. Here we show for the first time that human cord blood-derived cultured mast cells (hCBMC) at 10 wk, but not at 2 wk, are immunocytochemically positive for CRH and Ucn; human leukemic mast cells are weakly positive for both peptides. The ability of these mast cells to synthesize CRH and Ucn was confirmed by showing mRNA expression with RT-PCR. hCBMC (8-14 wk) synthesize and store 1-10 ng/106 cells (10-20 microg/g) of both CRH and Ucn detected by ELISA of cell homogenates. Stimulation of IgE-sensitized hCBMC with anti-IgE results in secretion of most CRH and Ucn. These findings indicate that mast cells are not only the target, but also a potential source of CRH and Ucn that could have both autocrine and paracrine functions, especially in allergic inflammatory disorders exacerbated by stress.

Hypokalemia, metabolic alkalosis, and hypertension: Cushing's syndrome in a patient with metastatic prostate adenocarcinoma

Ectopic adrenocorticotropic hormone (ACTH) and/or corticotropin-releasing hormone (CRH) are associated with a growing list of tumors. We report a 69-year-old white man with a history of high-grade prostate carcinoma and widely metastatic adenocarcinoma who presented with metabolic alkalosis, hypokalemia, and hypertension secondary to ectopic ACTH and CRH secretion. Laboratory values were consistent with hypokalemia and metabolic alkalosis. Markedly elevated serum cortisol (135 microg/dL), ACTH (1,387 pg/dL), CRH (69 pg/dL), and urine free cortisol (16,276 microg/24 h) levels were found. Chest computed tomographic (CT) scan showed small noncalcified parenchymal densities; however, bronchoscopy and bronchoalveolar lavage washings were unremarkable for a neoplastic process. Abdominal CT scan and magnetic resonance imaging showed multiple small liver lesions and multiple thoracic and lumbar intensities consistent with diffuse metastatic disease. Histological analysis of a biopsy specimen from the thoracic spine showed an undifferentiated adenocarcinoma consistent with a prostate primary tumor. The severe metabolic alkalosis secondary to glucocorticoid-induced excessive mineralocorticoid activity was treated with potassium supplements, spironolactone, and ketoconazole. In this case report, we describe an unusual tumor associated with ectopic ACTH and CRH production and the pharmacodynamic relationship of plasma cortisol levels and urinary cortisol excretion with ketoconazole treatment.

The BE (2)-M17 neuroblastoma cell line synthesizes and secretes corticotropin-releasing factor

The BE (2)-M17 human neuroblastoma has previously been shown to express corticotropin-releasing factor (CRF) mRNA following retinoic acid treatment. It is demonstrated in this report that both cell extracts and cell incubation medium of retinoic acid-treated BE (2)-M17 cells were shown to contain CRF-like immunoreactivity (CRF-LI) by RIA. CRF-LI secretion and content were also dose-dependently increased by forskolin. In addition, cell extracts were applied to a C18 Vydac column and peak CRF-LI from the collected fractions was shown to coincide in time of elution with peak immunoreactivity seen with oxidized synthetic CRF standard. Thus, in containing the CRF peptide, the BE (2)-M17 cells are useful models for further study of CRF cellular and genetic regulation.

Corticotropin-releasing factor is secreted in the BE(2)-C neuroblastoma cell and is responsive to forskolin

The BE(2)-C human neuroblastoma has been shown to express corticotropin-releasing factor (CRF) messenger RNA. In this study, BE(2)-C cells were treated 5 days with 5 microM retinoic acid. Cell extracts were also applied onto a C18 Vydac column and fractions were assayed for CRF-like immunoreactivity (CRF-LI) which coincided in time of elution with oxidized or non-oxidized CRF synthetic CRF standard. With forskolin treatment, secretion media and cell extract CRF-LI increased in a concentration-dependent fashion. Thus, this cell line synthesizes and secretes CRF and is a good model for studying CRF regulation.

Cushing's syndrome associated with ectopic production of corticotrophin-releasing hormone, corticotrophin and vasopressin by a phaeochromocytoma

We describe a case of Cushing's syndrome caused by a phaeochromocytoma secreting corticotrophin-releasing hormone (CRH) and corticotrophin (ACTH). A 49-year-old white woman presented with a 1-month history of lower limb oedema, polydipsia and polyuria. Physical examination revealed a patient with plethoric facies, lanugo-type facial hair, central obesity, red abdominal striae, lower limb oedema, and blood pressure of 210/115 mmHg. Laboratory studies showed high plasma ACTH and markedly elevated urinary cortisol excretion that suppressed more than 50% with high-dose dexamethasone administration. Computed tomographic scan of the abdomen showed a 4-cm left adrenal tumour. Catecholamines and metabolites were markedly increased in a 24-hour urine collection. Results of venous catheterization studies showed that CRH and ACTH were secreted by the tumour. In addition, with ovine CRH administration, inferior petrosal sinus sampling showed pituitary secretion of ACTH. Left adrenalectomy resulted in complete remission of Cushing's syndrome. Light microscopic and immunohistochemical studies revealed a phaeochromocytoma that produced CRH, ACTH and vasopressin. RNA studies showed that this tumour, in contrast to normal adrenal and other reported phaeochromocytomas, transcribed a lone pituitary-sized (1200 nucleotide) pro-opiomelanocortin mRNA. This is the second reported case of a CRH-secreting phaeochromocytoma.

Limited clinical usefulness of plasma corticotropin-releasing hormone, adrenocorticotropin and beta-endorphin measurements as markers of lung cancer

We measured plasma corticotropin-releasing hormone (CRH), ACTH, beta-endorphin (beta-EP), and cortisol levels as possible tumor markers in a sequence of 103, randomly selected, patients with lung cancer but without the ectopic Cushing's syndrome and in 72 age- and sex-matched controls. Plasma CRH levels of cancer patients were similar to those of controls both in patients sampled in the morning or in the afternoon. On the other hand, plasma ACTH levels of cancer patients were significantly higher than control patients both in the morning and in the afternoon and showed a preserved circadian rhythm. However, about 35% of cancer patients sampled in the morning and about 60% of those sampled in the afternoon had ACTH levels within the 95% confidence interval (CI) of controls. Also plasma beta-EP levels were more elevated in cancer patients than controls in the morning but about 33% of them and about 80% of those sampled in the afternoon had beta-EP levels within the 95% CI of controls. Despite the higher plasma ACTH levels, cancer patients had cortisol plasma levels similar to controls with preserved circadian rhythm. In conclusion, although mean plasma ACTH and beta-EP were higher in patients affected by lung cancer, their measurements, as well as those of CRH, have practically no diagnostic value. Perhaps measurement of ACTH levels in the bronchial lavage may be more helpful.

ACTH and CRF-producing bronchial carcinoid associated with Cushing's syndrome

A young female patient, with clinical and biochemical manifestations of severe hypercorticism and with the presence of a pituitary adenoma shown by computerized tomography, was thought to have Cushing's syndrome of hypophysial origin. However, the surgically-removed pituitary adenoma contained no ACTH, by immunocytology, and hypercorticism persisted after transsphenoidal adenomectomy. The patient died and autopsy demonstrated an ACTH and corticotrophin releasing factor (CRF)-containing bronchial carcinoid. It can be concluded that bronchial carcinoids can produce ACTH and CRF and can mimic the clinical and biochemical manifestations of pituitary Cushing's syndrome. Thus, the localization of the primary site of hypercorticism can be extremely difficult in patients who have an insidious, occult extrapituitary tumour. Further work is required to establish whether CRF plays a role in the causation of Cushing's syndrome and whether the simultaneous secretion of this peptide can modify the clinical and biochemical manifestations of the ectopic ACTH syndrome.