ACTH-producing Tumors Research Articles

Corticotropin-releasing hormone, proopiomelanocortin, and glucocorticoid receptor gene expression in adrenocorticotropin-producing tumors in vitro.

To differentiate between ectopic ACTH syndrome and Cushing's disease, gene expression of corticotropin-releasing hormone (CRH), proopiomelanocortin (POMC), and glucocorticoid receptor was examined in 10 pituitary adenomas (Cushing's disease) and in 10 ectopic ACTH-producing tumors. CRH increased plasma ACTH levels in all patients with Cushing's disease and in five patients with ectopic ACTH syndrome whose tumors contained CRH and CRH mRNA. In five CRH nonresponders, CRH was not detected in tumors that contained no CRH mRNA or that contained only long-size CRH mRNA. Dexamethasone (Dex) decreased plasma ACTH levels in all patients with Cushing's disease and in three patients with ectopic ACTH-producing bronchial carcinoid. These tumors contained glucocorticoid receptor mRNA. CRH increased and Dex decreased ACTH release and POMC mRNA levels in pituitary adenoma and bronchial carcinoid cells. PMA increased POMC mRNA levels only in carcinoid cells. These results reveal characteristics of ectopic ACTH-producing tumors: long-size CRH mRNA and PMA-induced POMC gene expression. In addition, there are two ectopic ACTH syndrome subtypes: tumors containing ACTH with CRH (CRH responder) and tumors without CRH. Dex decreases ACTH release and POMC mRNA levels in some bronchial carcinoids. Therefore, CRH and Dex tests have limited usefulness in differentiating between Cushing's disease and ectopic ACTH syndrome.

The radiological investigation of occult ectopic ACTH-dependent Cushing's syndrome

The radiological features of 14 patients with Cushing's syndrome due to 'occult' ectopic ACTH syndrome have been reviewed. In 11 of the 14 patients (79%), the ACTH-producing tumour was located in the thorax. Bronchial carcinoid tumours (eight patients) were the single most common source of 'occult' ectopic ACTH production with thymic carcinoid tumours (two patients) and mediastinal metastases from a medullary carcinoma of the thyroid gland (one patient) accounting for the other intrathoracic tumours. The tumours were usually small with five of the eight bronchial carcinoid tumours measuring between 4 and 10 mm in diameter. Since it remains difficult to distinguish between pituitary-dependent Cushing's disease and 'occult' ectopic ACTH-dependent Cushing's syndrome both clinically and biochemically, the role of radiology remains vital.

Unidentified steroid hormone of Cushing's syndrome and disease

A previously unknown HPLC peak was recently observed in urine samples from patients with Cushing's syndrome and disease. We analysed dansylated derivatives of 17keto steroid glucuronides in urine samples from patients with Cushing's syndrome, Cushing disease and from healthy subjects using high-performance liquid chromatography (HPLC) on reversed-phase Cap Cell PakC8. All urine samples from patients with Cushing's syndrome caused by adrenal adenoma and Cushing's disease showed an unknown large peak at the point between [110HE-G] and [110HA-G] peaks and at a retention time of 25.4 min. The same unknown peak was also observed in urine samples from a patient with asymptomatic cortisol-producing adrenal adenoma and two patients with ectopic ACTH-producing tumor, though the peak height was low for the former and one of the latter but high for the second of the two patients. In contrast, healthy male and female urine only showed a very small peak at the same retention time. Urine samples from a Cushing disease treated with op'DDD and Cushing's syndrome bilaterally adrenalectomized and treating with cortisol showed no such peak. The retention time of this unknown peak is clearly different from that of seven 17keto steroid standard glucuronide conjugates. The structure of this substance may be closely related to [110HE-G] or [110HA-G].

Percutaneous aspiration for hormone levels in the diagnosis of functioning endocrine tumors

Percutaneous aspiration to measure hormone levels in suspected functioning endocrine adenomas has been performed in 23 suspected cases of parathyroid adenomas, 7 cases of ACTH-producing thoracic carcinoid tumors, and 1 case of gastrinoma. When tumors secrete hormone or peptide markers, the biochemical assay can replace cytology to identify the lesion with greater specificity and at less expense.

Immunoreactive luteinizing hormone in functioning corticotroph adenomas of the pituitary

Two pituitary adenomas removed from a 37-year-old woman and a 26-year-old woman with typical Cushing's disease were studied by light and electron microscopy, immunohistochemistry and radioimmunoassay of tissue culture media. Both patients had high plasma levels of cortisol and normal levels of luteinizing hormone (LH). Both tumours were monomorphous, composed of densely granulated corticotrophs; the tumour cells contained periodic acid-Schiff positivity, were arranged in a sinusoidal pattern and, ultrastructurally, contained well-developed cytoplasmic organelles. By immunohistochemistry the majority of tumour cells contained immunoreactive adrenocorticotropin (ACTH); approximately 10% of the tumour cell population contained LH immunoreactivity. The LH-positive cells tended to form clusters scattered widely throughout the tumour tissues. LH immunoreactivity was demonstrated in some ACTH-immunoreactive cells on serial sections. Large amounts of immunoreactive ACTH and smaller quantities of LH, follicle stimulating hormone and alpha-subunit were released into the culture media and release of the glycoprotein hormones responded in parallel to corticotropin releasing hormone stimulation or inhibition by cortisol. These findings indicate that LH can be simultaneously produced and released by ACTH-producing tumour cells of otherwise typical functioning corticotroph adenomas. The capacity for LH production may be acquired during neoplastic proliferation. This is the first detailed report of concurrent production of LH by pituitary corticotroph adenomas.

Somatostatin Analogue(SMS 201-995) Decreases Plasma Levels of Corticotropin(ACTH) and Corticotropin-Releasing Hormone in a Patient with Ectopic ACTH-Producing Tumors.

Effects of long-acting somatostain analogue (SMS 201-995) on plasma corticotropin (ACTH) and corticotropin-releasing hormone (CRH) levels were studied in a patient (63-year-old woman) with ectopic ACTH-producing tumors associated with type I multiple endocrine neoplasia (MEN-I). The patient had undergone bilateral adrenalectomy. Plasma CRH, as well as plasma ACTH, beta-endorphin and alpha-MSH, increased. The hormone levels were dramatically decreased by acute administration of SMS 201-995. Moderately higher doses of dexamethasone (0.05 or 0.1 mg/kg a day) did not decrease plasma CRH or ACTH. An extremely high dose of dexamethasone (0.2 mg/kg a day), however, decreased plasma ACTH, but failed to decrease plasma CRH. Acute administration of SMS 201-995 further lowered the level of plasma ACTH even in this condition. In addition to the decrease in ACTH, SMS 201-995 decreased plasma CRH. Chronic administration of SMS 201-995 continuously decreased plasma CRH, ACTH and beta-endorphin. The decrease in these hormone concentrations accompanied the disappearance of hyperpigmentation. These results suggested that SMS 201-995 inhibits hypersecretion not only of ACTH but also of CRH, and that the agent is therapeutically useful in normalizing the hypersecretion of these hormones.

Failure of Bronchial Lavage to Detect Elevated Levels of Adrenocorticotropin (ACTH) in Patients with ACTH-Producing Bronchial Carcinoids

Saline lavage of the major bronchial segments was performed in five patients immediately preceding lobectomy to remove an ACTH-producing bronchial carcinoid. Lavage fluid from each bronchus was concentrated, and ACTH determinations were performed. Elevated concentrations of ACTH were not demonstrated in the aspirate from the bronchus containing the known tumor. Two additional patients with ectopic ACTH syndrome from an unknown primary source also underwent selective segmental bronchial lavage for ACTH determination. Neither patient demonstrated ACTH gradients in the lavage specimens. One was found to have an ACTH-producing bronchial carcinoid 18 months after negative lavage. Selective segmental bronchoscopic lavage with measurement of ACTH levels on the aspirate is not an effective technique for detecting ACTH-producing bronchial carcinoid tumor.

Ectopic adrenocorticotropic hormone syndrome: localization studies in 28 patients.

A variety of imaging procedures were performed in 28 patients with ectopic adrenocorticotropic hormone (ACTH) syndrome in an attempt to localize the ACTH-producing tumor. Diagnosis was made on the basis of removal of an ACTH-producing tumor or biopsy of metastases in the 19 patients with a proved source and the absence of ACTH gradients in bilateral samples of the inferior petrosal sinuses in the nine patients in whom an ACTH-secreting tumor had not been localized. Eleven bronchial carcinoids, two thymic carcinoids, three pheochromocytomas, and three islet-cell tumors constituted the proved sources. The condition has been cured in eight patients, six are alive with residual tumor, and five have died. Of the nine patients with undetected sites of ACTH production, one has died of pneumocystis pneumonia and eight are being treated medically or with bilateral adrenalectomy. Computed tomography (CT) of the chest and abdomen was the most helpful study in the detection of these tumors. Selective arteriography (bronchial and visceral), systemic and portal venous sampling, and iodine-131 meta-iodobenzylguanidine scintigraphy failed to demonstrate tumors when findings at CT were negative. Bronchial carcinoids constituted most of the ACTH-secreting tumors in this study (58%) and in a review of four large series (47%). To assure early detection of these potentially malignant tumors, pulmonary CT should be performed every 6 months, even after hypercortisolism has been medically or surgically controlled.

Effects of recombinant human interleukin-1α, -1β, 2 and 6 on ACTH synthesis and release in the mouse pituitary tumour cell line AtT-20

The effects of recombinant human interleukin (rhIL)-1 alpha, -1 beta, 2 and 6 on the release of ACTH from the ACTH-producing tumour cell line AtT-20 of the mouse were studied during relatively long periods of incubation. Levels of ACTH in the media, measured by radioimmunoassay, were increased by the addition of rhIL-1 alpha or -1 beta after latent periods of more than 4 h. RhIL-1 alpha and -1 beta were almost equally potent in this experiment and the minimum, half-maximum and maximum effective concentrations of both rhIL-1 alpha and -1 beta were about 0.1 pmol/l, 1-3 pmol/l and 10-100 pmol/l respectively. During incubation with rhIL-1 beta, immunoreactive ACTH levels and mRNA levels of the ACTH precursor pro-opiomelanocortin in cells also increased without apparent changes in the growth rate of the cells. Although the AtT-20 cells used in this study were quite insensitive to human/rat corticotrophin-releasing hormone (CRH), the cells showed a significant response to CRH after incubation with rhIL-1 beta. RhIL-6 showed similar effects to those of rhIL-1 beta on ACTH synthesis and release; increasing ACTH in cells and media after a certain latent period. On the other hand, rhIL-2 did not change ACTH levels in the AtT-20 cells in this study. These observations indicate that rhIL-1 alpha, -1 beta and rhIL-6 have direct effects on ACTH-producing cells to stimulate the release and synthesis of ACTH after a latent period.

Two-Site Immunoradiometric Assay for Adrenocorticotrophin: A Cautionary Study about the Reactivity to Its Precursor Molecules.

The specificity of a "two-site" immunoradiometric assay (IRMA) has been reevaluated by examining its ability to detect heterogeneous adrenocorticotrophin-like immunoreactivity (ACTH-LI) separated by gel column chromatography. Plasma samples from patients with Addison's disease, Nelson's syndrome and ectopic ACTH syndrome and tissue extract of human anterior pituitary were subjected to ACTH-IRMA and the levels of ACTH-LI were compared with those measured by conventional ACTH-radioimmunoassay (RIA). The level of ACTH-LI measured by IRMA was considerably lower than that measured by RIA in the plasma of a case of ectopic ACTH syndrome and the ACTH-LI did not show a dilution curve parallel with that of the standard. Gel exclusion chromatography revealed that the plasma contained a relatively large quantity of "big ACTH" which was found to be poorly detected by the IRMA. In the plasma of Addison's disease or the extract of pituitary gland in which "big ACTH" constituted a small portion, whole ACTH-LI was apparently diluted in parallel with the ACTH standard, although the "big ACTH" also did not show full parallelism with the ACTH standard in the IRMA. These data suggest that "big ACTH" derived not only from an ectopic ACTH-producing tumour but also from a normal human pituitary gland cannot be detected as well as authentic ACTH by the ACTH-IRMA system. Therefore, samples which contain a relatively large proportion of "big ACTH" in the total ACTH-LI should be carefully evaluated by ACTH-IRMA.

Gastrin in pituitary tumours.

Twelve of 87 pituitary adenomas from patients with acromegaly, Cushing's syndrome. Nelson's syndrome, hyperprolactinaemia and without symptoms of hormone hypersecretion contained gastrin in concentrations from 0.5 to 166 pmol/g. Only ACTH-producing tumours contained gastrin, which occurred in forms smaller than those present in the normal adenohypophysis. The results indicate that corticotropic tumours may synthesize gastrin in moderate amounts.

Cushing syndrome: pituitary CT scanning.

Proper treatment of patients with Cushing syndrome depends on knowledge of whether the condition derives from a pituitary or adrenal adenoma or an ectopic tumor that secretes adrenocorticotropic hormone (ACTH). Fifty-seven patients with Cushing syndrome were prospectively evaluated to determine whether computed tomography (CT) of the pituitary gland is useful in diagnosing or excluding an ACTH-producing adenoma and in predicting the site of the adenoma within the pituitary gland. Findings on CT scans were normal in 35 of 50 patients with surgically confirmed Cushing disease and in seven patients with ectopic ACTH-producing tumors. Of the 15 patients with Cushing disease for whom CT results were abnormal, eight had macroadenomas and seven had microadenomas. This study demonstrates a low sensitivity (30%) and low diagnostic accuracy (39%) of CT in the detection of ACTH-producing pituitary tumors and indicates the need for alternative methods of confirming the pituitary origin of excessive ACTH secretion in most patients.

Light bodies in human pituitary adenomas.

Light bodies are large cytoplasmic granules originally described in the gonadotrophic cells of the rat pituitary gland. In order to determine whether similar bodies occur in the human anterior pituitary gland, 89 pituitary adenomas and periadenomatous tissue from 20 cases were examined by transmission electron microscopy. Double membrane bound bodies with filamentous internal structure identical to rodent light bodies were identified in 10 hormone-producing adenomas: 5 PRL, 1 PRL-GH, 2 GH, and 2 ACTH-producing tumours. No light bodies were found in the remaining 79 tumours nor in the pituitary cells in periadenomatous tissue from 20 cases. These results show that some human pituitary adenomas may contain light bodies identical to those seen in gonadotrophs of rat pituitary.

Glucocorticoid incubation of human ACTH-producing pituitary tumours in vitro. A study on ACTH secretion and cell morphology.

ACTH-producing pituitary adenomas obtained from two patients with Cushing's disease were maintained in organ culture for 2 weeks. After 4-6 days of incubation, hydrocortisone (0.1, 1, and 5 mg/ml) was added to the culture medium. Addition of cortisol to the media in concentrations which generally inhibit the ACTH secretion in vivo in patients with Cushing's disease (1 mg/ml) failed to affect the ACTH secretion in vitro. A decrease of ACTH secretion occurred only with 5 mg/ml after 5 days of incubation. A similar effect on growth hormone (GH) release was seen when cortisol (10 mg/ml) was added to cultures from GH-producing pituitary adenoma. No ultrastructural changes were found in cultured cells that could be attributed to the addition of 0.1 mg/ml cortisol in the culture medium. With higher concentrations, (1 mg/ml and 5 mg/ml) minor ultrastructural changes were suspected. Our present findings implicate the hypothalamus as the target area for the feedback control of ACTH in Cushing's disease but could not reveal whether or not the primary lesion (i.e. the tumor) was of pituitary or hypothalamic origin. Our organ culture system appears to be a suitable model for investigating possible ACTH-regulating factors.

Pathobiologic study of pituitary tumors: Report of 62 cases with a review of the recent literature

Advances in radioimmunoassay procedures, immunocytochemistry, neuroradiologic imaging, and the surgical and medical treatment of pituitary adenomas have led to reappraisal of their classification as well as refinements in the diagnostic approaches used by pathologists. Sixty-two pituitary adenomas are described, and recent advances in this field are reviewed. Most of the patients were adults, but one of the adrenocorticotropic hormone (ACTH)-producing adenomas occurred in an 11-month-old infant. Endocrine-inactive tumors (43.5 per cent) were less common than hormone-producing tumors (56.5 per cent). Local invasion was most common in the former group, followed by ACTH-producing and other hormone-producing tumors. Ultrastructural features correlated with hormonal levels in the growth hormone(GH)-secreting tumors but not in the prolactin(LTH)- or ACTH-producing tumors. The formation of 7-nm filaments in the cytoplasm of tumor cells, corresponding to Crooke's hyaline change on light microscopy, was characteristic of ACTH-producing tumors. Ultrastructural changes in the ACTH granules suggested that the filaments may be derived from the feedback action of cortisol. Prior to surgery, a Rathke's cleft cyst and a chordoma were mistaken for endocrine-inactive pituitary adenomas. In two additional cases ectopic ACTH-producing tumors of lung clinically mimicked pituitary adenoma. Conversely, one pituitary adenoma mimicked sphenoid wing meningioma. Clinical, hormonal, and radiologic data and immunocytochemical and electron microscopic studies are needed for accurate pathologic interpretation and classification of pituitary adenomas.

Ectopic ACTH syndrome: Diagnostic and therapeutic aspects

Twenty-five patients were identified with non-pituitary, nonadrenal ACTH-secreting tumors (bronchial carcinoid, bronchial small cell carcinoma, pancreatic islet cell carcinoma, medullary thyroid carcinoma, thymic carcinoids, metastatic adenocarcinoma, and pancreatic cystadenoma). Clinical features were weakness, hypertension, cushingoid appearance, peripheral edema, personality disorders, and hyperpigmentation. Biochemical features were a markedly increased urinary free cortisol level (all patients), hypokalemia (71 percent of patients), and an elevated ACTH level (72 percent of patients). Surgical therapy consisted of bilateral total adrenalectomy (56 percent of patients). Twelve percent underwent transsphenoidal hypophysectomy and 36 percent had excision of their tumor. No surgical therapy was undertaken in 28 percent. Bilateral total adrenalectomy in patients with a slow-growing malignancy or an unknown tumor secreting ACTH is beneficial in relieving symptoms and prolonging life. Excision of nonmalignant ACTH-producing tumors yields an excellent long-term prognosis.

Light and electron microscopic localization of the N-terminal fragment of human pro-opiomelanocortin in the human pituitary gland and in neoplasms.

Immunohistochemical localization of the N-terminal fragment (1-76) (NTF) of human pro-opiomelanocortin (POMC) was studied in human adult and fetal pituitary glands, as well as in pituitary adenomas associated with Cushing's syndrome and in ectopic ACTH-producing tumors. Comparison of localization between NTF and ACTH was performed using mirror sections. Our results indicated concomitant localization of NTF and ACTH in the same cells, not only in normal adult and fetal pituitaries but also in pituitary adenomas and ectopic ACTH producing tumours. Specificity of the NTF staining was confirmed by immunoabsorption. Negative staining of the bovine pituitary gland indicated the immunohistochemical localization of N-terminal (1-45) of human POMC as there is a known species difference in the sequence 1-45 between human and the bovine N-terminal fragment. Presence of NTF in cisterna of rough endoplasmic reticulum indicates its production by small cell carcinoma. These findings, together with the previous studies, suggest that the complete form of POMC is produced in the tumours as well as in normal pituitaries.

Light and electron microscopic localization of ACTH and pro-opiomelanocortin-derived peptides in human developmental and neoplastic cells.

Oncofetal aspects of ACTH and pro-opiomelanocortin (POMC)-derived peptides were studied immunohistochemically at the light and electron microscopic level in human fetal pituitary glands, pituitary adenomas, and small-cell carcinoma of the lung. ACTH, beta-endorphin, and gamma-MSH were localized in the same cells of both fetal and adult pituitary, as well as in the above-mentioned neoplastic tissues. However, alpha-MSH was observed only in the early fetal pituitary, its concentration decreasing with advancing gestational age. The adult pituitary contained only a few alpha-MSH-positive cells. By immunoelectron microscopy, ACTH in the adult pituitary was localized exclusively in the secretory granules. In fetal pituitary at 9 weeks' gestation, ACTH was localized in the perinuclear spaces (PNS), cisternae of rough endoplasmic reticulum (RER), Golgi saccules, and secretory granules. The staining pattern of ACTH in these organelles varied from cell to cell. In fetal pituitaries of greater gestational ages, ACTH was localized in secretory granules. The pituitary adenomas mimicked the staining characteristics of the adult pituitary, i.e., negative or only very occasional alpha-MSH staining and localization of ACTH in the secretory granules. The ectopic ACTH-producing tumors showed a staining pattern similar to that of the early fetal pituitary, i.e., positive staining for alpha-MSH and the presence of ACTH in PNS and cisternae of RER.

DISSOCIATION BETWEEN PLASMA ADRENAL ANDROGENS AND CORTISOL IN CUSHING'S DISEASE AND ECTOPIC ACTH-PRODUCING TUMOUR: RELATION TO ADRENARCHE

To assess the effect of chronic hypersecretion of corticotropin (ACTH) and other peptides derived from proopiomelanocortin, and of cortisol, on plasma adrenal androgen concentration, plasma dehydroepiandrosterone sulphate (DHEA-S), dehydroepiandrosterone (DHEA), androstenedione (Δ4A), and cortisol were measured in 14 children and adolescents with Cushing's disease, a 9-year-old boy with an ectopic ACTH-producing tumour, and a group of normal, age-related individuals. The plasma DHEA-S concentration was normal for chronological age in 9 of 12 patients and for bone age in 7 of 10 patients. The plasma DHEA level was normal for chronological age in 12 of 14 patients and for bone age in 8 of 10 patients. In contrast, the concentration of plasma Δ4 A was raised for chronological age in 6 of 13 patients and for bone age in 7 of 10 patients. All patients had raised plasma cortisol levels in the afternoon and other laboratory and clinical signs of hypercortisolism. In the boy with an ectopic ACTH-producing tumour, plasma DHEA-S was moderately raised, plasma DHEA was normal, and plasma Δ4 A was very high. This patient's plasma ACTH levels ranged from 1340 to 1520 pg/ml and the cortisol levels from 51 to 95 μg/dl. The findings suggest that a factor other than ACTH is also required for adrenal androgen secretion. Since the other proopiomelanocortin-related peptides—ie, the N-terminal peptide (1-76), β-endorphin (β-EP), β-lipotropin (β-LPH), and γ-lipotropin (γ-LPH)—are raised in the plasma of patients with Cushing's disease, one of these is unlikely to be that putative factor.

Gamma irradiation effects on human ACTH-producing pituitary tumors in organ culture

Morphology (studied by light and electron microscopy) and hormone secretion were followed in organ cultures of adrenocorticotropic hormone (ACTH)-secreting hormones after in vitro irradiation with a single dose of 70 Gy. The increase is ACTH secretion immediately after exposure was interpreted as an irradiation-induced direct effect on cell membrane permeability. The low secretional capacity for 120 h after irradiation is probably caused by an impairment of cell metabolism. Cell morphology slightly deteriorated 24-48 h after exposure. Later, cell morphology was restored and specimens investigated 5 days after irradiation showed normal morphology. It is concluded, that the fluctuations in serum ACTH in patients with Cushing's disease treated by stereotactic radiosurgery are caused by changes in the tumor cells proper rather than being due to hypothalamic influence.