Regulation of glucocorticoid receptors in human mononuclear cells: effects of glucocorticoid treatment, Cushing's disease and ketoconazole

Comparison of chemotherapy outcomes between normal and high serum cortisol concentration in dogs with lymphoma

BACKGROUND

Increased serum cortisol (COR) concentrations may induce glucocorticoid resistance by down-regulation of glucocorticoid receptor (GCR), resulting in decreased chemotherapy efficacy in dogs with lymphoma.

HYPOTHESIS

Investigate the relationship between serum COR concentrations and chemotherapy outcomes in dogs with lymphoma.

ANIMALS

Thirty client-owned dogs with lymphoma, with serum COR concentration measured using serum samples collected at diagnosis.

METHODS

Retrospective study. Dogs were divided into 2 groups based on serum COR concentrations: a normal group (n = 16) with COR concentrations <6 μg/dL and a high group (14) with COR concentrations ≥6 μg/dL. We compared signalment, clinical signs, stage, type of lymphoma, adrenal gland size, alkaline phosphatase (ALP) activity, response to chemotherapy, progression-free survival (PFS), overall survival (OS), and rate of P-glycoprotein (P-gp)- and GCR-positive cells between the 2 groups.

RESULTS

No significant differences were found in the demographic characteristics between the 2 groups. However, the high COR group exhibited a significantly lower response to chemotherapy, PFS, and OS compared with the normal COR group. Serum ALP activity was significantly higher in the high COR group than in the normal COR group. Adrenal gland size was also significantly larger in the high COR group. Although no significant differences were found in the rate of P-gp-positive cells between the 2 groups, the rate of GCR-positive cells was significantly lower in the high COR group.

CONCLUSIONS AND CLINICAL IMPORTANCE

Our data suggests that measurement of serum COR concentrations may serve as a potential prognostic factor and evaluation index.

Cushing's disease: current medical therapies and molecular insights guiding future therapies

OBJECT Cushing's disease (CD) can lead to significant morbidity secondary to hormonal sequelae or mass effect from the pituitary tumor. A transsphenoidal approach to resection of the adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma is the first-line treatment. However, in the setting in which patients are unable to undergo surgery, have acute hypercortisolism, or have recurrent disease, medical therapy can play an important role. The authors performed a systematic review to highlight the efficacy of medical treatment of CD and discuss novel molecular insights that could guide the development of future medical treatments of CD. METHODS A search on current medical therapies for CD was performed. After individual medical therapeutic agents for CD were identified, each agent underwent a formal systematic search. The phrase "(name of agent) and Cushing's" was used as a search term in PubMed for all years up to 2014. The abstract of each article was reviewed for studies that evaluated the efficacy of medical treatment of CD. Only studies that enrolled at least 20 patients were included in the review. RESULTS A total of 11 articles on 6 individual agents were included in this review. Specific medical therapies were categorized based on the level of action: pituitary directed (cabergoline and pasireotide), adrenal/steroidogenesis directed (ketoconazole, metyrapone, and mitotane), and end-tissue directed/cortisol receptors (mifepristone). The studies identified consisted of a mix of retrospective reviews and small clinical trials. Only pasireotide and mifepristone have undergone Phase III clinical trials, from which they garnered FDA approval for the treatment of patients with CD. Overall, agents targeting ACTH secretion and steroidogenesis were found to be quite effective in reducing urine free cortisol (UFC) to levels near normal. A significant reduction in UFC was observed in 45%-100% of patients and a majority of patients gained clinical improvement. Similarly, inhibition at the end-tissue level led to clinical improvement in 87% of patients. However, side-effect rates associated with these drugs are high (up to 88%). Ketoconazole has been shown to enhance tumor appearance on MRI to facilitate pituitary resection. Promising molecular targets have been identified, including epidermal growth factor receptor, retinoic acid receptors, and cyclin dependent kinases. These pathways have been linked to the regulation of pro-opiomelanocortin expression, ACTH secretion, and tumor growth. CONCLUSIONS Despite encouraging Phase III clinical trials leading to FDA approval of 2 agents for treatment of patients with CD, no agent has yet produced results comparable to resection. As a result, the molecular insights gained into CD pathogenesis will need to continue to be expanded until they can lead to the development of medical therapies for CD with a favorable side-effect profile and efficacy comparable to resection. Ideally these agents should also reduce tumor size, which could potentially permit their eventual discontinuation.

Ketoconazole revisited: a preoperative or postoperative treatment in Cushing's disease

CONTEXT

Although transsphenoidal surgery remains the first-line treatment in Cushing's disease (CD), recurrence is observed in about 20% of cases. Adjunctive treatments each have specific drawbacks. Despite its inhibitory effects on steroidogenesis, the antifungal drug ketoconazole was only evaluated in series with few patients and/or short-term follow-up.

OBJECTIVE

Analysis of long-term hormonal effects and tolerance of ketoconazole in CD.

DESIGN

A total of 38 patients were retrospectively studied with a mean follow-up of 23 months (6-72).

SETTING

All patients were treated at the same Department of Endocrinology in Marseille, France.

PATIENTS

The 38 patients with CD, of whom 17 had previous transsphenoidal surgery.

INTERVENTION

Ketoconazole was begun at 200-400 mg/day and titrated up to 1200 mg/day until biochemical remission.

MAIN OUTCOME MEASURES

Patients were considered controlled if 24-h urinary free cortisol was normalized.

RESULTS

Five patients stopped ketoconazole during the first week because of clinical or biological intolerance. On an intention to treat basis, 45% of the patients were controlled as were 51% of those treated long term. Initial hormonal levels were not statistically different between patients controlled or uncontrolled. Ketoconazole was similarly efficacious as a primary or postoperative treatment. Among 15 patients without visible adenoma at initial evaluation, subsequent follow-up allowed identification of the lesion in five cases. No adrenal insufficiency was observed. Adverse effects were rare in patients treated long term.

CONCLUSIONS

Ketoconazole is a safe and efficacious treatment in CD, particularly in patients for whom surgery is contraindicated, or delayed because of the absence of image of adenoma on magnetic resonance imaging.

The effect of dexamethasone on defective nephrin transport caused by ER stress: a potential mechanism for the therapeutic action of glucocorticoids in the acquired glomerular diseases

The mechanism by which glucocorticoids govern antiproteinuric effect in nephrotic syndrome remains unknown. Present study examined the protective role of dexamethasone (DEX) in the intracellular trafficking of nephrin under endoplasmic reticulum (ER) stress. Human embryonic kidney-293 cell line expressing a full-length human nephrin was cultured in mediums containing 5.5 or 25 mM glucose with or without DEX. The result revealed that glucose starvation evoked a rapid ER stress leading to formation of underglycosylated nephrin that was remained in the ER as a complex with calreticulin/calnexin. DEX rescued this interfered trafficking through binding to its receptor and stimulating the mitochondrial transcripts and adenosine 5' triphosphate (ATP) production, leading to synthesis of fully glycosylated nephrin. These results suggest that ER-stress in podocytes may cause alteration of nephrin N-glycosylation, which may be an underlying factor in the pathomechanism of the proteinuria in nephrotic syndrome. DEX may restore this imbalance by stimulating expression of mitochondrial genes, resulted in the production of ATP that is essential factor for proper folding machinery aided by the ER chaperones.

Subcellular localization of glucocorticoid receptor protein in the human kidney glomerulus

BACKGROUND

The detailed mechanisms of glucocorticoid action in idiopathic nephrotic syndrome and progressive glomerulonephritides have not been clearly elucidated. The pharmacological actions of glucocorticoids are mediated by their binding to an intracellular protein, the glucocorticoid receptor (GR). The determination of GR localization in normal glomerular cells is essential to elucidate the mechanisms of glucocorticoid action in various glomerular diseases.

METHODS

We carried out an immunoblot examination using antihuman GR-specific antibody and homogenates of isolated normal human glomeruli and mesangial cells in culture. Immunohistochemical examinations were also performed on normal human kidney specimens at light and electron microscopic levels. The nuclear translocation of GRs elicited by ligand binding was further investigated by confocal laser-scanning microscopic inspection of freshly isolated glomeruli and mesangial cells cultured with dexamethasone.

RESULTS

An immunoblot examination demonstrated the presence of a 94 kDa protein, a molecular weight consistent with that of GRs, in the homogenates of glomeruli and cultured mesangial cells. By light microscopic examination, GRs were strongly detected in the nucleus and moderately in the cytoplasm of all glomerular cells, parietal and visceral epithelial cells, endothelial cells, and mesangial cells. By electron microscopic examination, the nuclear GRs of all glomerular cells were found to be diffusely distributed in the euchromatin. Additionally, the immunofluorescence intensities of nuclear GRs in isolated glomeruli and mesangial cells in culture became more intense by the addition of dexamethasone.

CONCLUSIONS

Our findings suggest that all subsets of human glomerular cells definitely express the GR protein, which potentially undergoes translocation by glucocorticoids.

Glucocorticoid receptors in anorexia nervosa and Cushing's disease

BACKGROUND

Patients with anorexia nervosa do not display cushingoid features in spite of elevated cortisol plasma levels. Whether a cortisol resistance or a reduced availability of the metabolic substrates necessary to develop the effect of glucocorticoids is responsible for this has not been established.

METHODS

Twenty-two patients with severe restrictive anorexia nervosa, 10 patients with active Cushing's disease, and 24 healthy volunteers without psychiatric disorders or mood alterations were investigated. Glucocorticoid receptor characteristics were examined on mononuclear leukocytes by measuring [3H]dexamethasone binding and the effect of dexamethasone on [3H]thymidine incorporation, which represents an index of DNA synthesis.

RESULTS

The number of glucocorticoid receptors on mononuclear leukocytes (MNL) was comparable in patients with anorexia nervosa, patients with active Cushing's disease, and normal subjects (binding capacity 3.3 +/- 0.23 vs. 3.7 +/- 0.30 and 3.5 +/- 0.20 fmol/10(6) cells). Conversely, glucocorticoid receptor affinity was significantly decreased in anorexia nervosa as well as in Cushing's patients compared to control subjects (dissociation constant 4.0 +/- 0.31 and 4.1 +/- 0.34 vs. 2.9 +/- 0.29 nmol/L, p < .001) and inversely correlated with the levels of urinary free cortisol in both groups of patients. Basal [3H]thymidine incorporation in MNL was significantly reduced in anorexia nervosa as well as in Cushing's patients compared to control subjects (p < .001) and was diminished by dexamethasone to an extent similar to control subjects in patients with anorexia nervosa, but significantly (p < .001) less in those with Cushing's disease. In patients with anorexia nervosa, the incorporation of [3H]thymidine into the MNL was inversely correlated with urinary free cortisol levels.

CONCLUSIONS

These data indicate that the lack of cushingoid features in patients with anorexia nervosa is not ascribable to a reduced sensitivity to glucocorticoids but is more likely due to the paucity of metabolic substrates.

The modulation of glucocorticoid receptor content by 3-O-methyl-D-glucose transport in human mononuclear leukocyte in obesity

Glucocorticoid receptors (GR) and 3-O-methyl-D glucose (3-O-MG) transport were determined in mononuclear leukocytes (MNL) from 11 abdominal obese subjects, 10 pituitary-dependent Cushing's syndrome (Cushing's disease) and 10 healthy controls. Using a whole-cell competitive binding assay and 3H-dexamethasone as tracer, MNL of abdominal obese subjects were found to have 4855 +/- 1389 sites/cell which was significantly lower (p < 0.05) than controls (6234 +/- 1568 sites/cell), although no significant difference was found in the mean serum cortisol level. Their mean Kd (affinity) was also significantly lower than that found in the healthy controls (obese Kd:2.92 +/- 0.84 nmol/l, control Kd: 4.55 +/- 0.67 nM, p < 0.05). On the other hand, the receptor characteristics in Cushing's disease patients were within the normal range. At the same time, 3-O-MG transport was determined in the same subjects. In Cushing's disease, 3-O-MG transport was within the normal range, whereas in abdominal obesity this value was significantly lower than the healthy controls (abdominal obese: 31.90 +/- 8.20; control: 46.26 +/- 12.91 fmol/10(6) cell, min, p < 0.05). We also found a positive correlation between 3-O-MG transport and GR binding capacity in abdominal subjects (r = 0.89, p < 0.001), however we did not find such a correlation in Cushing's disease (r = 0.60, p > 0.05). These results indicated that, in abdominal obesity, the GR binding capacity in MNL is influenced by the changes in glucose transport.

Glucocorticoid receptors in human peripheral blood mononuclear cells in relation to age and to sport activity

Glucocorticoid receptors (GR) are ubiquitous molecules and are present also in the hippocampus and in several other nervous and immune tissues. Peripheral blood mononuclear cells (PBMCs) are a good model for studies of GR in humans. Glucocorticoids are important for maintaining cellular and humoral homeostasis and are key mediators of neuroendocrine-immune regulatory interactions. The increase of cortisol is immunosuppressive and reduces GR concentration both in nervous and immune systems. Variation of glucocorticoids in healthy aged subjects and athletes has been shown. Prompted by these results, we have investigated in man a possible relationship between GR binding capacity in the PBMCs and age, in relation also to plasma testosterone and cortisol. The same parameters have been examined in a group of soccer players for comparison with the sedentary group. GR binding capacity was higher in younger subjects than in older ones, and lower in the group of athletes than in the younger and older sedentary subjects. In the sedentary group a negative correlation was present between GR binding capacity and age. Plasma cortisol was higher and testosterone lower in the athletes; they were negatively correlated in athletes and positively correlated in the sedentary subjects. The results for athletes agree with their lower anabolic/catabolic balance. The mechanism of reduced GR levels in relation to age and sport activity could involve a loss or an involution of receptor synthesis. However other possibilities, such as altered distribution of lymphocyte subpopulations with different receptor concentrations and with different cytokine production, cannot be excluded. Several neuroendocrine-immune interactions could be responsible for reduced GR levels with age and sport activity in man.

The effect of long-term glucocorticoid therapy on glucocorticoid receptor content and on steroid response to ACTH

The effect of long-term glucocorticoid therapy for systemic diseases on glucocorticoid receptor (GR) content and on basal and ACTH-stimulated levels of plasma and salivary cortisol 17 alpha-hydroxy-progesterone, androstenedione, 11 beta-hydroxyandrostenedione, DHEA, its sulfate and sex hormone-binding globulin (SHBG), as well as on basal levels of aldosterone, was investigated in a group of 24 children treated with prednisone for at least 8 months. The therapy was interrupted 24 h before the ACTH test and before plasma and saliva sampling. The control group consisted of 21 healthy children of corresponding age and sex. The patients were divided into two subgroups with normal and subnormal basal cortisolemia, they also differed in their response to ACTH. The GR levels in patient groups were indistinguishable from those found in controls. No correlation was found between GR content and basal levels of the above steroids or their response to ACTH. The best markers, apart from basal cortisolemia, for evaluation of the degree of suppression of adrenal function appeared to be the response of salivary (but not of plasma) cortisol and 17 alpha-hydroxy-progesterone to ACTH. Surprisingly, significantly lower levels of SHBG levels, which rose markedly after ACTH, were found in all the patients.

Corticosteroid receptors and aging

We have measured plasma aldosterone, plasma cortisol, and glucocorticoid and mineralocorticoid receptors in mononuclear leukocytes in 54 healthy aged subjects (60-97 years old) and in a group of 21 controls (21-50 years old). In addition all parameters and age were plotted for correlation. Plasma cortisol was significantly higher in the aged group (346 +/- 140 nmol/l) than in controls (260 +/- 120). Mean plasma aldosterone was not different in the two groups. Both Type I and II receptors in mononuclear leukocytes were lower in the aged group than in controls (Type I 198 +/- 96 and 272 +/- 97 receptors per cell; Type II 1738 +/- 801 and 3339 +/- 918 receptors per cell). A direct correlation was found between cortisol and age and between Type I and II receptors in aged subjects, and between cortisol and Type I receptors, and cortisol and Type II receptors in controls. When all subjects are plotted together, a direct correlation was observed between cortisol and age and between Type I and II receptors, and an inverse correlation between age and Type I and age and Type II receptors. We conclude that the parallel reduction of both Type I and II receptors with age is not due to prior cortisol increase, but the increase of plasma cortisol can be considered the result of age-dependent involution of these receptors.