Progesterone is extensively metabolized in osteoblasts: implications for progesterone action on bone

The effect of progestogens on bone is controversial with some studies suggesting an anabolic action while others show no effect. Prereceptor metabolism via localized expression of specific enzymes may have major impact on progesterone action in bone and may explain some of the discrepancies between studies. We therefore investigated the metabolism of progesterone in primary cultures of human osteoblasts and MG-63 osteoblastic cells. Osteoblasts and MG-63 cells were incubated with 4- (14)C-progesterone tracer and 50 nM unlabeled progesterone, and magnitude and pattern of progesterone metabolism were determined by two-dimensional thin-layer chromatography. Conventional and Taqman real-time PCR analysis were used to assess expression of progesterone metabolizing enzymes. In both types of cells the two major metabolic products of progesterone were 20 alpha-dihydroprogesterone and 5 alpha-dihydroprogesterone, but conversion to 3 alpha, 5 alpha- and 3 beta, 5 alpha-tetrahydroprogesterone was also detected. This activity was concomitant with expression of mRNAs for the enzymes AKR1C1, 5 alpha-reductase type 1 and AKR1C2, and 3 beta-HSD type 1 and 3-hydroxysteroid epimerase. In MG-63 cells progesterone metabolism was largely mediated via 5 alpha-reductase. In primary osteoblasts progesterone metabolism was unaffected by treatment with dexamethasone or estradiol, but in MG-63 cells dexamethasone pretreatment increased 5 alpha-reductase activity. Progesterone is subject to extensive intracellular inactivation in human osteoblasts, with potential attenuation of local progesterone receptor responses. Conversely, osteoblasts have the capacity to convert progestogens to metabolites reported to have anabolic actions through the estrogen receptor.

[Treatment of adult men with congenital adrenal hyperplasia syndrome due to 21-hydroxylase deficiency]

Information about the treatment of males with congenital adrenal hyperplasia (CAH) is scarce and there are no therapeutical guidelines. The aim of this review is to provide a survey of the current data. An extensive literature research was performed in PubMed for relevant articles published in the last ten years. The aim in the treatment of adult male CAH patients is preservation of fertility, prevention of an addisonian crisis, blood pressure management, prevention of testicular adrenal rest tumors (TART), maintaining well-being and good quality of life, satisfactory sexual function and prevention of long-term side effects of gluco- and mineralocorticoid therapy. The change from paediatric to adult medicine should be handled in a transition outpatient clinic organized by paediatric and adult endocrinologists. Most studies have included only small numbers of patients. The steroid therapy is usually orientated on an individual basis; but, general guidelines are lacking. It is reported that fertility is often impaired and related to the occurrence of TART. Some of these tumors are responsive to altered glucocorticoid therapy. However, glucocorticoid-resistant TART have been described, and testis-sparing surgery seems to be a treatment option. A future system of regular follow-up visits and standardized therapy guidelines are essential to provide a better medical care and a higher quality of life for male patients with CAH.

Effect of immunosuppressive and other drugs on the cortisol-cortisone shuttle in human kidney and liver

BACKGROUND

Impaired 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) has been suggested in patients with hypertension or renal disease, where it may contribute to sodium retention and hypertension. 11beta-HSD1, which is expressed predominantly in liver and adipose tissue, influences glucose homeostasis and fat distribution by altering intracellular cortisol (F) concentrations. We tested immunosuppressive drugs that cause hypertension, and substances that interfere with steroidogenesis or influence glucose homeostasis for their ability to influence the inhibition of 11beta-HSD isozymes.

METHODS

For inhibition experiments, we used microsomes prepared from unaffected parts of human liver segments and resected human kidney cortex because of hepatocarcinoma or renal cell cancer. The inhibitory potency of several compounds was evaluated in concentrations from 10(-9)-10(-5) mol/l.

RESULTS

Only sirolimus, but not cyclosporine A, tacrolimus, mycophenolate mofetil, or azathioprine showed a slight inhibition of 11beta-HSD2 activity. None of the drugs that inhibit steroidogenesis (suramine, mitotane, etomidate, and aminogluthethimide) or steroid metabolism (rifampicine) influenced 11beta-HSDs, nor did ginsenoides Re, Rc, and Rb1. Among sulfonylureas, only gliclazide decreased significantly 11beta-HSD1 activity.

CONCLUSIONS

Increased blood pressure due to immunosuppressive drugs is probably not caused by direct inhibition of 11beta-HSD2. An additional glucose lowering effect of sulfonylurea gliclazide may be due to its ability to inhibit 11beta-HSD1.

Assessment of suspected insulinoma by 48-hour fasting test: a retrospective monocentric study of 23 cases

OBJECTIVE

Insulinoma causes fasting hypoglycaemia due to inappropriate insulin secretion. The diagnosis of insulinoma is based on Whipple's triad during a supervised fasting test. The aim of our study was to evaluate retrospectively the percentage of positive 48-hour fasting tests in a large series of patients with insulinoma.

DESIGN, PATIENTS AND METHODS

In a retrospective study, we identified 39 patients (24 females, 15 men; average age 47 years [range 12-78 years]) with insulinoma. Sixteen patients were diagnosed by spontaneous hypoglycaemia. Twenty-three patients with insulinoma were tested with a 48-hour fasting test and compared to 31 healthy controls who had a negative fasting test and were followed up for at least two years.

RESULTS

The fast was terminated due to neuroglycopenic symptoms in 4 patients (17.4%) at the 12th hour, in 17 patients (73.9%) at the 24th hour, and in 22 patients (95.7%) at the 48th hour. One patient with insulinoma had no neuroglycopenic symptoms, but was diagnosed by glucose and insulin levels during the 48-hour fast. Healthy controls had significantly higher blood glucose and lower insulin levels, and a lower insulin-glucose ratio than patients with insulinoma at the end of the fast.

CONCLUSIONS

In conclusion, the 48-hour fasting test was successful in the diagnosis of insulinoma in 95.7% of patients. In this series we did not observe a need for fasting beyond 48 hours.

Epidermal growth factor receptor (EGFR) as a potential new target in the treatment of patients with adrenocortical carcinoma: Results of pre-clinical studies

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Background: Adrenocortical carcinoma (ACC) is a rare malignancy with incompletely understood pathogenesis and poor prognosis. Overexpression of epidermal growth factor receptor (EGFR) has been demonstrated in several tumors and is partly associated with a more aggressive phenotype and a worse prognosis. In addition, targeting the EGFR tyrosine kinase represents a successful new therapeutic strategy, e.g. in non-small cell lung cancer. Therefore, we investigated the role of EGFR in ACC as a potential therapeutic target. Methods: EGFR expression was analyzed by immunohistochemistry in 115 ACCs and 5 normal adrenals using paraffin sections and tissue arrays (scoring of expression: 0–3). Utilizing the clinical data from the German ACC registry, Kaplan Meier survival analyses were performed. In 30 patients the tumor DNA was sequenced for mutations of the “hot spot” exons 19–21 of the EGFR gene. In addition, cells of the ACC cell line NCI-h295 were incubated with the EGFR antibody cetuximab (1–100 μg/ml) and cell proliferation was measured by MTT tests. Results: Immunohistochemistry revealed EGFR expression in 78% of ACCs. In 67/115 (58%) of the ACCs and 0/5 of the normal adrenals the expression level was judged as moderate-to-high (score 2 or 3). However, the expression level did not correlate with the clinical outcome in these patients. In addition, none of the sequenced tumor DNA samples showed a mutation in exons 19–21. Cetuximab exhibited a dose dependent antiproliferative effect in NCI-H295 cells (cell viability: 1μg/ml: 95±2%; 10μg/ml 90±3%*; 100 μg/ml 85±4%* vs untreated control cells: 100±3%; * = p<0.01). Conclusion: EGFR is overexpressed in the majority of ACC. Moreover, in vitro experiments demonstrated that inhibition of EGFR signalling lead to moderate growth inhibition in ACC cells. Therefore, in patients with ACC refractory to established cytotoxic therapies the experimental use of EGFR inhibitors (combined with cytotoxic therapy) seems to be justified.

No significant financial relationships to disclose.

Expression profiling of 11beta-hydroxysteroid dehydrogenase type-1 and glucocorticoid-target genes in subcutaneous and omental human preadipocytes

Obesity is associated with increased morbidity and mortality from cardiovascular disease, diabetes and cancer. Although obesity is a multi-factorial heterogeneous condition, fat accumulation in visceral depots is most highly associated with these risks. Pathological glucocorticoid excess (i.e. in Cushing's syndrome) is a recognised, reversible cause of visceral fat accumulation. The aim of this study was to identify depot-specific glucocorticoid-target genes in adipocyte precursor cells (preadipocytes) using Affymetrix microarray technique. Confluent preadipocytes from subcutaneous (SC) and omental (OM) adipose tissue collected from five female patients were treated for 24 h with 100 nM cortisol (F), RNA was pooled and hybridised to the Affymetrix U133 microarray set. We identified 72 upregulated and 30 downregulated genes by F in SC cells. In OM preadipocytes, 56 genes were increased and 19 were decreased. Among the most interesting were transcription factors, markers of adipocyte differentiation and glucose metabolism, cell adhesion and growth arrest protein factors involved in G-coupled and Wnt signalling. The Affymetrix data have been confirmed by quantitative real-time PCR for ten specific genes, including HSD11B1, GR, C/EBPalpha, C/EBPbeta, IL-6, FABP4, APOD, IRS2, AGTR1 and GHR. One of the most upregulated genes in OM but not in SC cells was HSD11B1. The GR was similarly expressed and not regulated by glucocorticoids in SC and OM human preadipocytes. C/EBPalpha was expressed in SC preadipocytes and upregulated by F, but was below the detection level in OM cells. C/EBPbeta was highly expressed both in SC and in OM preadipocytes, but was not regulated by F. Our results provide insight into the genes involved in the regulation of adipocyte differentiation by cortisol, highlighting the depot specifically in human adipose tissue.

[Modern pharmacological aspects of hyperaldosteronism therapy]

The prevalence of primary hyperaldosteronism is 5-10% of all hypertensive patients, and clearly above the estimated prevalence in the past. In nearly 30% of patients with therapy resistant hypertension, primary hyperaldosteronism is detected if they are investigated thoroughly. This will result in 1.5 to 2.5 million people in Germany suffering from primary hyperaldosteronism. Besides efficient diagnostic procedures, an effective treatment is of increasing importance. The aldosterone-producing adenoma (Conn's syndrome) is primarily cured by operation, in most cases performed endoscopically. Bilateral hyperplasia, which is found in two-thirds of primary hyperaldosteronism, is treated primarily by mineralocorticoid receptor antagonist: 12.5-50 mg/day spironolactone (in case of anti-androgenic side-effects alternatively by 50-100 mg/day eplerenone). If the blood pressure can not be lowered by this first-line treatment, an additional treatment with potassium-sparing diuretics, calcium-antagonists, ACE-inhibitors or angiotensin-2-antagonists is necessary. The start of medication should be closely monitored by serum electrolyte and creatinine controls.

The relationship between albuminuria, MCP-1/CCL2, and interstitial macrophages in chronic kidney disease

Glomerular-derived proteins may activate tubular cells to express the macrophage-directed chemokine monocyte chemoattractant protein-1 (MCP-1/CCL2). Macrophages at interstitial sites have a central role in directing renal scarring. We have prospectively assessed the relationship between albuminuria, urinary MCP-1/CCL2, interstitial macrophage infiltration, in situ damage, and clinical outcomes in a large group of patients with chronic kidney disease. We studied 215 patients and quantified albumin-creatinine ratio (ACR), urinary MCP-1/CCL2, interstitial macrophage numbers, and in situ damage. ACR correlated with urinary MCP-1/CCL2 (correlation 0.499; P<0.001), interstitial macrophage numbers (correlation 0.481; P<0.001), and index of chronic damage (correlation 0.363; P<0.001). Macrophage numbers closely correlated with in situ damage (correlation 0.755; P<0.001). By multivariate analysis ACR, urinary MCP-1/CCL2, and interstitial macrophage numbers were interdependent. By Kaplan-Meier survival analysis albuminuria, urinary MCP-1/CCL2, interstitial macrophages, and chronic damage predict the outcome. ACR, macrophage numbers, chronic damage, and creatinine independently predicted renal survival. The association of ACR with other variables was strongest in patients with less advanced disease states. There is a close association between albuminuria, urinary MCP-1/CCL2, and interstitial macrophage infiltration with in situ damage and clinical outcomes. These findings support the hypothesis that albuminuria triggers tubular MCP-1/CCL2 expression with subsequent macrophage infiltration. These processes may represent the dominant pathway for the progression of renal injury before the establishment of advanced renal scarring.

Pharmacodynamics and pharmacokinetics of synthetic mineralocorticoids and glucocorticoids: receptor transactivation and prereceptor metabolism by 11beta-hydroxysteroid-dehydrogenases

Glucocorticoid (GC) and mineralocorticoid (MC) action in target tissues is determined by prereceptor metabolism by 11beta-hydroxysteroid-dehydrogenases (HSDs) and receptor transactivation. We characterized these parameters for steroids often used in clinical practice. HSD activity was examined in human liver (HSD1) and kidney microsomes (HSD2) and in CHO cells stably transfected with both enzymes. GC and MC transcriptional activity was tested by luciferase assay in CV-1 cells transfected with human GC or MC receptor expression vectors. The 11-hydroxy-group is necessary for GC and MC receptor transactivation. As HSD2 oxidizes 11-hydroxysteroids to inactive 11-dehydrosteroids, GC and MC activity in HSD2-expressing tissues (kidney, colon) is regulated by this enzyme. As 9alpha-fluorination (such as in 9alpha-fluorocortisol) decreases oxidation by HSD2 and increases both GC and MC receptor transactivation, this modification leads to optimal, but non-selective transactivation of both receptors. Increased GC receptor and decreased MC receptor transactivation leading to more selective GC activity is reached using the following substituents: 16beta-methyl (in betamethasone), 16alpha-methyl (in dexamethasone) and triangle up 1-dehydro-configuration (in prednisolone). Whereas the modifications in position 16 decrease oxidation by HSD2, the triangle up 1-dehydro-configuration increases HSD2-activity leading to an enhanced inactivation of prednisolone compared to all other steroids. 9alpha-fluorocortisol, the most frequently used substance for MC-substitution, seems to be the best choice of available steroids for this purpose. Whereas GC selectivity can be improved by hydrophobic substituents in position 16 and the triangle up 1-dehydro-configuration, maximal GC activity needs additional fluorination in position 9alpha (such as in dexamethasone). For GC therapy directed to HSD2-expressing organs, widely used prednisolone does not seem to be the optimal recommendation.