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F Beuschlein

Publications and source records attributed to F Beuschlein.

At least 19 recordsLinked to original sources
PubMed2006

[Obesity 2006].

Despite the fact that the last decade has seen major advances in our knowledge of obesity, the average unsatisfactory successes of lifestyle changes and pharmacological treatment strategies clearly show how very far obesity research and treatment still has to go. What is most regrettable, however, is the fact that, in contrast to the WHO, the German Social Security Code V does not recognize obesity as a disease. This means ignoring the approaching flood of costs associated with obesity, which will put a great strain our health system.

Adolescent↗
PubMed2006

[Genetics and pathophysiology of obesity].

Obesity is one of the major health problems in developed countries. More than 35% of adults in Germany are considered to be overweight (BMI 25-29.9 kg/m(2)) and approximately 15-20% to be obese (BMI >30 kg/m(2)). Overweight and obesity result from chronic disruption of energy balance. Recent progress in understanding of appetite control and energy expenditure has elucidated a complex integrated system of energy homoeostasis. Although changes in nutritional habits and reduction of physical activity are the main characteristics leading to the strong increase in obesity, it is now recognized that obesity is not only caused by a lack of will power, but can be a consequence of metabolic defects. As obesity results from a genetic make-up favoring weight gain in an "obesigenic" environment the elucidation of the underlying molecular mechanisms might be translated in novel therapeutic options in the future.

Appetite Regulation↗
PubMed2006

Spontaneous cerebrospinal fluid rhinorrhea in untreated macroprolactinoma--an indication for primary surgical therapy.

BACKGROUND: Medical therapy is usually indicated as first-line treatment for prolactinomas. Surgery is generally reserved as second-line therapy if prolactinomas are non-responsive to dopamine agonists (DA) or DA therapy is not tolerated. Herein, we draw attention to the rare occurrence of spontaneous CSF rhinorrhea in prolactinomas requiring primary surgical therapy. Only 8 cases of confirmed prolactinomas with spontaneous rhinorrhea have been reported in the literature so far. CASE REPORTS: Two out of 267 surgical cases with pituitary adenomas presented with spontaneous rhinorrhea. Both patients harbored invasive prolactinomas. In both cases, the defect was exposed using a transsphenoidal procedure and was sealed with fascia lata. RESULTS: Urgent surgical repair of the leak prevented meningitis. In one case, a second operation was required due to recurrent rhinorrhea under postoperative dopamine-agonist therapy of the residual tumor. The clinical course was otherwise uncomplicated. CONCLUSION: Certain clinical settings still require primary surgical therapy of prolactinomas. Spontaneous rhinorrhea caused by invasive macroprolactinomas represents a mandatory indication for initial surgery. Early detection and surgical repair of a CSF leak is crucial for a favorable clinical outcome.

Adult↗
PubMed2005

Growth hormone receptor mRNA expression in non-functioning and somatotroph pituitary adenomas: implications for growth hormone substitution therapy?

The use of growth hormone (GH) in patients with GH deficiency induced by pituitary adenoma is widely accepted, but the safety of this mitogenic hormone, particularly in patients with residual tumor after neurosurgery, continues to be a concern. Since the mitogenic potency of GH is dependent upon the presence of the GH receptor (GH-R) and the subsequent IGF-1/IGF receptor (IGF-1-R) system we investigated the expression of the members of the growth hormone cascade in endocrine inactive and GH-producing pituitary adenomas. Tissue specimens of 18 clinically non-functioning pituitary adenomas and 6 GH-producing adenomas were collected following transsphenoidal surgery while normal cadaver pituitary glands served as controls. After RNA extraction, semi-quantitative RT-PCR amplification with specific primers for GH, GH-R, IGF-1 and IGF-1-R was performed. Applying this sensitive RT-PCR based approach, GH-R expression was demonstrated in all normal pituitaries, most inactive adenomas (94%), and the majority of GH-producing adenomas (66%). Both IGF-1 and IGF-1-R mRNA was detectable in the majority of inactive (72% and 77%, respectively) and somatotrophic adenomas (83% and 83%). While IGF-1-R mRNA was expressed in all normal pituitary specimen studied, IGF-1 was detectable in only 55% of them. In summary, expression of members of the GH-IGF-1 cascade could be demonstrated in a substantial subset of patients with non-functioning and GH-producing pituitary adenomas. These factors might serve as a substrate for the transduction of mitogenic effects of GH on remnant pituitary tumors during GH replacement therapy. Therefore, GH therapy should be carefully considered and patients on GH therapy kept under close observation.

Acromegaly↗
PubMed2005

Low-dose glucose infusion after achieving critical hypoglycemia during insulin tolerance testing: effects on time of hypoglycemia, neuroendocrine stress response and patient's discomfort in a pilot study.

OBJECTIVE: The insulin tolerance test (ITT) is regarded as the gold standard for the evaluation of pituitary ACTH and growth hormone reserve. However, the intended critical hypoglycemia results in considerable discomfort and requires close surveillance during the test. DESIGN AND METHODS: In a pilot study, we evaluated whether the ITT could be markedly simplified, made less hazardous and more convenient by routine i.v. low-dose glucose administration after hypoglycemia has been achieved. Sixteen healthy subjects (three females, 13 males) were tested twice in a randomized, single-blinded fashion, receiving 0.15 IU insulin/kg body weight as an i.v. bolus. After hypoglycemia (serum glucose less than 2.2 mmol/l) had been achieved, 500 ml isotonic saline (protocol A (A)), or 500 ml 5% glucose solution (protocol B (B)) were infused over 30 min. RESULTS: Compared with saline, glucose infusion shortened the period of hypoglycemia from 31 + 14 to 17 + 6 min (P < 0.01). In addition, prolonged duration of hypoglycemia (>45 min) was reduced (6 subjects in protocol A vs none in protocol B). Despite shorter duration of hypoglycemia, all subjects had adequate stimulated cortisol (>500 nmol/l) and hGH (>5 microg/l) levels. Mean peak concentrations of plasma ACTH (24 +/- 12 pmol/l (A) vs 21 +/- 8 pmol/l (B)), serum cortisol (690 +/- 83 nmol/l vs 634 +/- 83 nmol/l) and serum hGH (26 +/- 16 microg/l vs 22 +/- 13 microg/l) were slightly, but not significantly lower. In contrast, glucose infusion significantly reduced peak plasma epinephrine levels at 45 min (4.96 +/- 4.91 pmol/l (A) vs 1.53 +/- 1.1 pmol/l (B), P < 0.05) and ameliorated discomfort, as evaluated by a visual analog scale (P < 0.05). CONCLUSIONS: Taken together, our pilot study suggests that, while the duration of hypoglycemia is shortened and acute epinephrine response is reduced, low-dose infusion of glucose does not significantly alter peak cortisol and growth hormone responses during ITT. Studies with a larger number of subjects and patients with suspected hypopituitarism are needed to further evaluate this modified protocol.

Adrenocorticotropic Hormone↗
PubMed2004

The role of the ACTH receptor in adrenal tumors: identification of a novel microsatellite marker.

In vitro, the growth inhibiting effect of ACTH on adrenocortical cells is well documented, even though there are reports of opposite effects under defined cell culture conditions. In vivo, activation of the ACTH receptor (ACTHR) has a trophic effect on the adrenal cortex, while the effects on proliferation are still under discussion, especially since other POMC derived peptides have been characterized. However, ACTH is thought to act as a differentiation factor with inhibiting effects on tumor growth. In undifferentiated adrenocortical carcinomas, ACTHR expression is frequently lost, which is associated with extensive tumor growth. We describe a new microsatellite marker within the intron of the ACTHR gene termed ACTHRint1. In a series of 114 patients with various adrenal and non-adrenal tumors, the rate of heterozygosity was 100 %. Only one out of 57 patients with adrenocortical adenoma showed LOH at the ACTHR locus, whereas 4 of 10 carcinomas had loss of one allele. Patients suffering from tumors with LOH showed a more aggressive disease course and had earlier recurrences with poor prognosis. These data confirm earlier findings that adrenocortical carcinomas frequently show loss of ACTHR expression, which is associated with a more aggressive tumor growth. However, whether the ACTHR is directly involved in tumor growth or acts a marker of differentiation that is lost in more advanced tumor stages is still not clear.

Adrenal Cortex↗
PubMed2004

Cytotoxic T-cell response against steroidogenic acute regulatory protein using DNA vaccination followed by vaccinia virus infection in a mouse adrenal carcinoma model.

Adrenocortical carcinoma (ACC) is still one of the most devastating human tumors with a five year survival as low as 20 %. In a previous study, we showed that DNA vaccination followed by vaccinia virus was able to break immune tolerance against murine steroidogenic acute regulatory (mStAR). Prophylactic vaccination in syngenic mice resulted in protective immunity against Sp2-0 tumor cells expressing mStAR. However, approximately a third of the animals developed tumors despite vaccination. This prompted us to investigate whether vaccination failure is responsible for this phenomenon. BALB/cBALB/c mice (in groups of 6 - 9 animals) were vaccinated intramuscularly by injection of cDNA expression vectors encoding mStAR three times at weekly intervals. This was followed by a recombinant vaccinia virus (rVV-mStAR) infection to boost immune response. Ten days after the last vaccination, Sp2-mStAR or parental Sp2-0 cells (as controls) were injected s. c. Tumor development was monitored by daily palpation. Approximately two weeks later, the animals were sacrificed and the spleens removed. After restimulation with the cell lines expressing mStAR, the splenocytes were tested for presence of mStAR self-reactive cytotoxic T-lymphocytes using ELISPOT analysis. With this approach, we were able to show that those animals protected from tumor growth had a specific T-cell response against StAR whereas mice without a specific T-cell response developed Sp2-mStAR tumors. Our data demonstrate that vaccination failure, probably due to the low antigenicity of mStAR, is responsible for tumor growth in our model system.

Adrenal Gland Neoplasms↗
PubMed2004

Role of the inhibin/activin system and luteinizing hormone in adrenocortical tumorigenesis.

Adrenal masses are one of the most common endocrine tumors diagnosed. Although most adrenal tumors are inactive adenomas, a considerable proportion is associated with hormonal hyperfunction and/or malignancy. The adrenocortical carcinoma (ACC) is a rare but highly malignant tumor. Most ACCs in adults are diagnosed in an advanced tumor stage limiting therapeutic options. Accordingly, despite some progress in diagnostic and therapeutic approaches, the overall survival rate of patients with ACC remains poor. However, the prerequisite for the development of new diagnostic tools and therapeutic options in the management of patients with ACC is the elucidation of the molecular pathogenesis of adrenal tumorigenesis. Although our understanding of adrenal tumor biology has increased substantially over the last decades, the regulation of many molecular pathways involved in adrenocortical growth and differentiation awaits further elucidation. Luteinizing hormone (LH) and activin have only recently emerged as hormones likely to play opposite roles in adrenocortical hormone secretion and cellular proliferation. Recent evidence from studies on human surgical tumor sample expression and detailed characterization of murine adrenal tumor models suggests stimulatory effects of LH on adrenocortical growth and function. On the contrary, activin, which plays a critical role as a paracrine and autocrine factor regulating cellular growth and differentiation, has been demonstrated to induce apoptosis and suppress proliferation in the human and murine adrenal cortex. In this review, we will summarize molecular and functional aspects of adrenal tumorigenesis and highlight some prospects for future clinical applications.

Activins↗
PubMed2003

High diagnostic accuracy of adrenal core biopsy: results of the German and Austrian adrenal network multicenter trial in 220 consecutive patients.

Incidentally detected adrenal tumors are a common finding during abdominal ultrasonography, computed tomography, and magnetic resonance imaging. Although most of these lesions are benign adenomas, adrenocortical carcinomas and metastases constitute 5% to 10% of all tumors. Adrenal biopsy may be helpful, but its diagnostic value is controversial and disputed, and prospective studies have not yet been performed. Therefore, the diagnostic accuracy of adrenal core biopsy was evaluated in a prospective multicenter study involving 8 surgical centers in Germany and Austria. A total of 220 biopsies from surgical specimens of the adrenal gland were punctured in an ex vivo approach and processed for pathohistologic diagnosis using paraffin sections, routine staining, and immunohistochemistry (keratin KL1, vimentin, S100 protein, chromogranin A, synaptophysin, neuron-specific enolase, D11, MiB-1, and p53 protein). The evaluating pathologist was blinded for clinical data from the patients. A total of 89 adrenal adenomas (40.5%), 22 adrenal carcinomas (10.0%), 55 pheochromocytomas (25.0%), 15 metastases (6.8%), 16 adrenal hyperplasias (7.2%), and 23 other tumors (10.5%) were studied. Nine cases were excluded due to incomplete data (n = 2) or insufficient biopsy specimen (n = 7). In the remaining 211 tumors, compared with the final diagnoses of the surgical specimen, bioptic diagnoses were absolutely correct in 76.8% of the cases, nearly correct in 13.2% of the cases, and incorrect in 10% of the cases. Pheochromocytomas were correctly diagnosed in 96% of the cases, cortical adenomas were correctly or nearly correctly reported in 91% of the cases, cortical carcinomas were correctly or nearly correctly reported in 76% of the cases, and metastases were correctly or nearly correctly reported in 77% of the cases. Of the 39 malignant lesions, only 4 were misclassified, 2 as benign and 2 as possibly malignant. This resulted in an overall sensitivity for malignancy of 94.6% and specificity of 95.3%. Our findings suggest that adrenal core biopsy is a useful method for identifying and classifying adrenal tumorous lesions if sufficient biopsy specimens can be obtained. However, in clinical practice it remains to be shown whether the benefits of biopsy outweigh the risks of the procedure.

Adenoma↗
PubMed2002

SF-1, DAX-1, and acd: molecular determinants of adrenocortical growth and steroidogenesis.

The formation of the adrenal cortex in humans is notable for the presence of two discrete zones, the fetal zone (FZ) which regresses soon after birth and the definitive zone (DZ) which gives rise to the classic steroidogenic zones of the adult cortex. Mice possess an analogous structure to the FZ referred to as the X-zone (XZ) which regresses at puberty in the male and during the first pregnancy in the female. Similar to the human FZ in X-linked Congenital Adrenal Hypoplasia caused by loss of function mutations in DAX-1 (Dosage-sensitive sex reversal-Adrenal hypoplasia congenita critical region on the X chromosome), the mouse XZ does not regress when DAX-1 is mutated. Only in humans with DAX-1 mutations, however, is the DZ small and hypofunctional. Patients and mice with SF-1 mutations have complete adrenal aplasia with absence of both the DZ and FZ/XZ. Lastly, the phenotype of the Autosomal Recessive Adrenocortical Dysplasia (acd) mouse is strikingly similar to human Miniature Adult Congenital Adrenal Hypoplasia, lacking an XZ/FZ and possessing a dysfunctional DZ. Current work has addressed the regulation of SF-1 and DAX-1 dependent adrenocortical growth and steroidogenesis in vivo utilizing mouse models of simple and combined SF-1 and DAX-1 deficiency. In addition, the model of compensatory adrenal growth in SF-1 haplo-insufficient mice has been applied to evaluate the potential role of SF-1 in adrenocortical proliferation. Additional efforts aim to positionally clone the acd gene, predicated on the hypothesis that it is a critical component of the adrenal developmental cascade.

Adrenal Cortex↗
PubMed2001

Angiotensin II type 1 receptor and ACTH receptor expression in human adrenocortical neoplasms.

OBJECTIVE: Type 1 angiotensin II (Ang II) receptors transduce most of the known actions of Ang II, including steroidogenesis and trophic actions on the adrenal cortex. We investigated the type 1 Ang II receptor expression in adrenocortical tissues to define its regulation in adrenocortical neoplasms and to compare its expression with that of the ACTH receptor (ACTH-R). PATIENTS AND MEASUREMENTS: Poly A RNA was extracted from tumour tissue and electrophoresed through a 1.0% agarose gel, blotted and hybridized with alpha32P-CTP labelled PCR generated type 1 Ang II receptor cDNA probe. Receptor autoradiography was performed on slices from normal adrenals and tumour tissue by incubation with 125I-Sar1, Ile8-Ang II with and without pretreatment with cold Ang II or with the selective type 1 receptor antagonist losartan. RESULTS: Ang II type 1 receptor mRNA was high in cortisol producing (CPA; n = 5) and aldosterone producing (APA; n = 4) adenomas (normal adrenals 100 +/- 12% vs. 180 +/- 16% in CPA and 154 +/- 26% in APA, mean +/- SEM), but was low in nonfunctioning adenomas (NFA; n = 2; 2 +/- 1%). ACTH receptor mRNA followed a similar pattern (CPA 178 +/- 17, APA 196 +/- 30, NFA 0%, carcinomas 56 +/- 11%) with a good correlation between Ang II type 1 receptor and ACTH-R mRNA of r = 0.692, P = 0.0019. Receptor autoradiography in normal adrenals demonstrated Ang II type 1 receptors predominantly in the zona glomerulosa. In tumour tissue, mainly type 1 receptor expression was found confirming the Northern blot data. CONCLUSIONS: Angiotensin II type 1 receptor and ACTH receptor expression seems to be correlated with the functional status of adrenocortical tumours, suggesting regulation by similar factors. The predominant receptor expressed in adrenocortical tumours is the Angiotensin II type 1 receptor whereas type 2 receptor expression is minimal.

Adenoma↗
PubMed2001

ACTH-receptor expression, regulation and role in adrenocortial tumor formation.

The regulation of the ACTH-receptor gene is unique in that it is up-regulated by its own ligand, ACTH. Ligand-induced up-regulation of ACTH-receptor expression may be an important adaptive process directed towards optimizing adrenal responsiveness to ACTH in the context of physiological stress and the maintenance of metabolic homeostasis in which the adrenals play a pivotal role. Whereas enhancement by ligand-induced up-regulation permits a more efficient and rapid glucocorticoid response, negative feedback regulation of glucocorticoids in the hypothalamus and pituitary inhibits ACTH secretion and allows a balanced adrenal response to stress. Since the cloning of the promoter region of the ACTH receptor, considerable progress in the understanding of the regulatory processes has been made. The effects of ACTH on ACTH-receptor expression is dependent on cAMP, probably mediated through AP-1. The profound effect of three SF-1-binding sites in the ACTH-receptor promoter was demonstrated by deletion experiments. Conversely, ACTH-receptor expression can be suppressed by adrenal-specific transcription factors,like DAX-1. Despite an extensive search, no activating ACTH-receptor mutations have been found in adrenal tumors,excluding the ACTH receptor as a relevant oncogene in adrenal tumorigenesis. However, the ACTH receptor may act as a differentiation factor as suggested by LOH in adrenal carcinomas with an undifferentiated tumor type. In benign adrenal tumors, a strong correlation between ACTH-receptor expression and expression of P450 steroidogenic enzymes is evident. This close regulative relationship is lost in adrenal carcinoma, probably as a result of tumor dedifferentiation. Down-regulation of ACTH-receptor expression in normal and neoplastic tissue can be achieved by adrenostatic compounds such as aminoglutethimide and metyrapone.

Adrenal Cortex Neoplasms↗
PubMed2001

Discerning malignancy in adrenocortical tumors: are molecular markers useful?

OBJECTIVE: Adrenocortical carcinoma (ACC) is a rare neoplasm with poor prognosis. Discerning ACCs from benign adenomas histologically may be difficult if invasion into surrounding tissues or metastases are missing. DESIGN: In order to establish molecular markers for malignancy, we analyzed seven normal adrenals, three massive macronodular ACTH-independent adrenocortical hyperplasias (MMAHs), 30 adrenocortical adenomas (ACAs) and ten ACCs. METHODS: All tissues were studied for the presence of alterations in the p53 tumor suppressor gene using the PAb 1801 antibody, which detects mutant p53 protein and the pYNZ22 microsatellite marker to show loss of heterozygosity (LOH) at 17p, for expression of the proliferation-associated antigen Ki67 using the MIB1 antibody, for the rate of apoptotic tumor cells with the TdT-mediated dUTP biotin nick end labeling (TUNEL) method, and for LOH of 11q13 (menin gene locus) with the D11S956 microsatellite marker. RESULTS: 0/3 MMAH, 1/28 ACA and 3/10 ACC revealed immunopositive staining for p53. LOH for pYNZ22 was observed in 1/3 MMAH, 1/23 informative ACA and 6/6 informative ACC. The rate of apoptotic cells was significantly higher in ACC (P<0.0001 by ANOVA) than in ACA but there was some overlap between groups. The Ki67 index (% immunopositive cells) was 1.9+/-1.30% (mean+/-s.d.) in normal adrenals, 3.47+/-1.37% in MMAH, and 2.11+/-1.01% in ACA. ACC had the highest Ki67 index of 11.94+/-7.58% distinguishing all ACC from the ACA and MMAH studied with a cut-off level of 5%. LOH for 11q13 was detected in 2/3 MMAH, 5/26 ACA and 6/8 ACC. CONCLUSIONS: We conclude that a Ki67 index above 5% is a sensitive and specific indicator of ACC and may be useful in the differentiation of adenomas from carcinomas.

Adenoma↗
PubMed2000

Oral glucose tolerance testing but not intravenous glucose administration uncovers hyper-responsiveness of hypothalamo-pituitary-adrenal axis in patients with adrenal incidentalomas.

OBJECTIVE: Modern imaging techniques are detecting adrenal incidentalomas with increasing frequency. Recent data suggests food-dependent hypercortisolism in a subgroup of patients with bilateral macronodular hyperplasia due to aberrant adrenal responsiveness to gastric inhibitory polypeptide (GIP). We studied the putative influence of food intake on the hypothalamo-pituitary-adrenal (HPA) axis in patients with adrenal incidentalomas and possible mediation by GIP. PATIENTS AND MEASUREMENTS: We examined 15 mildly obese patients with adrenal incidentalomas, eight healthy, lean subjects, and seven obese patients with the metabolic syndrome, who were matched for body weight and age. Each individual underwent oral glucose tolerance testing (OGTT, 75 g glucose), i.v. glucose administration (IVGTT, 30 g glucose over 1 h) and i.v. glucose plus GIP infusion (body weight adapted leading to physiological postprandial GIP serum levels) on three occasions. Plasma glucose, ACTH and cortisol were measured from blood samples taken every 15 minutes from time - 30 minutes to + 75 minutes. RESULTS: OGTT, i.v. glucose administration and GIP infusion led to comparable glucose values within the groups. In contrast to normal subjects and patients with the metabolic syndrome, patients with adrenal incidentalomas had significantly higher mean cortisol values after oral glucose intake as compared to i.v. glucose administration or GIP infusion. The increase in cortisol levels was preceded by a corresponding ACTH increase. No significant effect of GIP administration on cortisol or on ACTH secretion could be detected. CONCLUSIONS: Patients with adrenal incidentalomas showed an abnormal responsiveness of the pituitary-adrenal axis to oral glucose administration. The cortisol peaks in these patients seemed to be ACTH-mediated and were not induced by GIP.

Adenoma↗
PubMed2000

Molecular adrenocortical tumourigenesis.

Adrenocortical neoplasms are the most frequent abnormality of the adrenal cortex. Most of these lesions are clinically silent and are detected incidentally by ultrasound or computed tomography. The prevalence of these so-called 'incidentalomas' in the general population is around 1%, increasing with age and reaching 6% among those in the age range 60-70 years. In contrast, primary adrenocortical carcinoma, a highly malignant tumour, is rare, having an incidence of one case per million per year. Recent progress has been achieved in the understanding of adrenocortical tumourigenesis by mapping and identification of genes responsible for hereditary tumours that involve the adrenal gland. Investigation of the clonal composition of adrenal tumours demonstrates that adrenal carcinomas are monoclonal, whereas adrenal adenoma may be polyclonal in approximately 25-40% of cases. Oncogenes and tumour-suppressor genes involved in adrenal carcinomas include mutations in the p53 tumour-suppressor gene and rearrangements of the chromosomal locus 11p15.5 associated with IGF II hyperexpression. Constitutive activation of the ACTH receptor-G protein-cAMP signal cascade does not play a role in adrenal tumour formation. Conversely, deletions of the ACTH receptor gene have recently been found in undifferentiated adenomas and in aggressive adrenocortical carcinomas, and, more recently, confirmed in a larger series of tumours. The available literature indicates that the signalling pathways of adrenocortical tumours are different from those of other endocrine neoplasms, such as pituitary and thyroid adenomas.

Adenomatous Polyposis Coli↗
PubMed2000

New mechanisms of adrenostatic compounds in a human adrenocortical cancer cell line.

BACKGROUND: Adrenostatic compounds are frequently used in the treatment of patients with Cushing's syndrome and act via direct inhibition of steroidogenic enzymes. However, additional mechanisms may be involved in the blockade of adrenal steroid secretion. We therefore investigated the effects of aminoglutethimide (AG), metyrapone (MTP) and etomidate (ETO) in the human NCI-h295 adrenocortical carcinoma cell line. MATERIALS AND METHODS: Cells were incubated with increasing doses of the adrenostatic compounds. Steroid hormone secretion (cortisol, 17-OH-progesterone, DHEA-S) and cAMP synthesis were determined and Northern blot analysis and cell proliferation experiments were performed. RESULTS: ETO was the most potent adrenostatic compound inhibiting P450c11 hydroxylase at low concentrations (IC50 15 nM), and also blocking P450 side-chain cleavage (scc) enzyme (IC50 400 nM) at higher concentrations. The pattern of enzyme inhibition was similar for MTP with an IC50 of 3-5 microM for P450c11 and 17 microM for P450scc, while AG blocked P450scc with an IC50 of 10 microM. AG significantly suppressed the baseline ACTH-R mRNA expression in a dose-dependent fashion (300 microM AG: 5% +/- 1%; 30 microM AG: 64% +/- 1%; 3 microM AG: 108% +/- 19% compared with control cells: 100% +/- 11%) but increased glucocorticoid receptor mRNA. The reduced ACTH-R mRNA was paralleled by low ACTH-induced cAMP accumulation indicating reduced expression of ACTH-R protein. The simultaneous incubation of hydrocortisone together with AG reversed the inhibitory effect of AG on the ACTH-R expression. AG and ETO inhibited cell proliferation in the NCI-h295 cells, but ETO was much more potent and showed antiproliferative effects at concentrations of 6 microM. The growth inhibition was not reversed by administration of hydrocortisone. CONCLUSIONS: Our data demonstrate that adrenostatic compounds not only act by suppression of steroidogenic enzymes but can also influence both ACTH-R expression and cell proliferation in adrenal cells. As these effects occur in vitro at concentrations that are reached during treatment with these drugs in patients, they are probably also of clinical relevance. Particularly the antiproliferative activity of ETO may be useful in Cushing's syndrome due to adrenocortical cancer. The interaction of steroidogenesis, ACTH-R and glucocorticoid receptor expression as well as cell proliferation provides a new concept of the intra-adrenal response to stress in humans.

Adrenal Cortex Neoplasms↗
PubMed2000

Steroidogenic acute regulatory protein mRNA expression in adrenal tumours.

The rate limiting step in steroidogenesis is cholesterol transport through the outer to the inner mitochondrial membrane and the cytochrome P450 side chain cleavage (P450scc) complex. The protein factor responsible for this transport, and as such necessary for regulating the acute production of steroids, has been identified and named the steroidogenic acute regulatory protein (StAR). We investigated the expression of StAR in functional and non-functional adrenal neoplasms and compared the expression with that of P450scc. Poly A RNA was extracted from normal adrenal glands (NAG, n=5), aldosterone producing adenomas (APA, n=4), cortisol producing adenomas (CPA, n=5), adrenocortical carcinomas (ACC, n=6) and non-functional adenomas (NFA, n=3), electrophoresed through a 1% agarose gel, blotted and hybridised with a PCR-generated cDNA labelled with [(32)P]CTP. The blots were stripped and re-hybridised with a P450scc cDNA and a mouse beta-actin probe. Compared with P450scc, StAR mRNA expression showed little variability in the magnitude of expression and did not correlate with the endocrine profiles (NAG: StAR 100+/-16%, P450scc 100+/-14%; APA: StAR 80+/-3%, P450scc 94+/-13%; CPA: StAR 71+/-10%, P450scc 109+/-15%; NFA: StAR 64+/-9.5%, P450scc 18+/-5%; means+/-s.e.m.). ACC expressed low levels of both genes probably as a result of dedifferentiation (StAR 29+/-9%, P450scc 46+/-18%). Incubation of the NCI-h295 tumour cell line with 10nmol ACTH and 10micromol forskolin induced an increase in the abundance of StAR and P450scc mRNA, demonstrating gene regulation by the cAMP protein kinase A pathway. Furthermore, we incubated the NCI-h295 tumour cell line with the adrenostatic compounds, aminoglutethimide and metyrapone. We could not detect an effect on the expression of StAR mRNA, whereas the expression of P450scc mRNA was significantly reduced. We conclude that, in contrast to P450scc, StAR seems to be evenly expressed in adrenocortical adenomas. Therefore, the endocrine activity of a given tumour cannot be explained by the abundance of StAR expression. In ACC, both StAR and P450scc expression is low, explaining the relatively inefficient steroid production of these tumours.

Adenoma↗