Study Of Glucocorticoid Receptors Research Articles

Study of glucocorticoid receptors in T lymphocytes (CD3/GCR) as predictor of steroid responsiveness in Egyptian children with idiopathic nephrotic syndrome.

Little was known about the relationships between the T lymphocytes (CD3+), expression of glucocorticoid receptors (GCR) and the response to GC treatment in children with the idiopathic nephrotic syndrome (INS). Our objective was to determine the relation between steroid responsiveness and GCR expression in T lymphocytes. The present study was carried out on 80 children with new-onset INS admitted in Pediatric Nephrology Units of Zagazig and Tanta University Hospitals and on 40 healthy children of the same age and sex who served as control group. The Subjects were subdivided into three groups as follows: Group 1 with 40 healthy children of comparable age and sex served as control group; Group 2 consisted of 60 patients diagnosed with INS with early response to steroid therapy [early responder (ER)] and Group 3 with 20 patients diagnosed with INS with late response to steroid therapy [late responder (LR)]. They were subjected to history taking, focusing on the pattern of response to steroids (ERs), clinical examination, routine laboratory investigations and the GCR/CD3% relationship. 75% of newly diagnosed INS cases were ER whereas 25% were LR. GCR/CD3% was significantly lower in LR group in comparison with ER and control groups, with a significant negative correlation between time of steroid responsiveness and GCR/CD3%. LR group showed lower GCR expression in T lymphocytes before starting therapy which may mean that GCR expression could be part of a pathophysiological mechanism of steroid responsiveness in these children and can be used as a useful diagnostic marker to predict steroid responsiveness in patients with INS.

Abstract P6-12-15: Efficacy results of a phase 1/2 study of glucocorticoid receptor (GR) antagonist mifepristone (MIFE) in combination with eribulin in GR-positive triple-negative breast cancer (TNBC)

Abstract Background: GR is variably expressed in TNBC and high expression is associated with poor prognosis in estrogen receptor-negative (ER-) early stage breast cancer. Treatment with mifepristone (MIFE) potentiates the effectiveness of chemotherapy in GR+ TNBC xenografts. Enrollment is complete in this study of patients with GR+ TNBC treated at the recommended Phase 2 dose (RP2D) of MIFE in combination with eribulin. Objectives: To determine the safety, tolerability, pharmacokinetics (PK) and clinical activity of the MIFE plus eribulin combination in pts with GR+ TNBC at the RP2D. Methods: Eligibility: In Part 1 (dose finding), pts with solid tumors; in Part 2 (expansion phase), pts with TNBC (GR result required at time of screening in Part 1, but could be pending at time of screening in Part 2). Up to 5 prior chemotherapy regimens for advanced disease; ECOG PS 0-1; adequate end-organ function. Design: 3 + 3 dose escalation scheme. After a 7-day lead-in of oral daily MIFE alone, MIFE was continued daily and eribulin was given on days 1 and 8 of a 21-day cycle. GR+ was defined as >10% of tumor cells with any intensity of GR staining. Results: 16 pts with metastatic breast cancer were treated in Part 1, and 21 pts with TNBC were treated in Part 2. Median age was 54 (range 30-81). MTD/RP2D was MIFE 300 mg/day + eribulin 1.1 mg/m2. Safety: DLT in Part 1 was neutropenia. Neutropenia occurred in 23/36 total patients (2 Grade [G] 1, 10 G3, 11 G4); 2 instances included neutropenic fever. Recovery of WBC was brisk with growth factor support. Neuropathy was observed in 8 pts (5 G1, 1 G2, 2 G3). Other most common AEs (fatigue, hypokalemia, nausea, alopecia) were mainly G1 or G2; among these, G3/G4 events were limited to fatigue (4 G3), hypokalemia (3 G3 and 1 G4) and nausea (1 G3). There were 2 instances of G1 vaginal bleeding. There was no impact of MIFE on eribulin PK. Efficacy: There were 23 evaluable pts with TNBC across Parts 1 and 2 treated at the RP2D: 21 GR+, 2 GR status unknown; median of 3 prior chemotherapy regimens; 1 patient had received prior eribulin. Responses were: 3 PR, 8 SD, 11 PD and one too early to assess. Median PFS was 9 weeks. Conclusions: MIFE plus eribulin was well tolerated and appears to be an active treatment regimen. Five TNBC patients had a PFS longer than the upper 95% CI for PFS (i.e., >15 wks) reported by Aogi et al. for TNBC treated with eribulin (Annals of Oncology 2012?23:144148). Clinical trial information: NCT02014337. Citation Format: Han HS, Wilks S, Paplomata E, Modiano MR, Becerra C, Braiteh FS, Spira AI, Pluard TJ, Richards DA, Conzen SD, Baker G, Fishman RS, Marcantonio A, O'Shaughnessy J, Nanda R. Efficacy results of a phase 1/2 study of glucocorticoid receptor (GR) antagonist mifepristone (MIFE) in combination with eribulin in GR-positive triple-negative breast cancer (TNBC) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-12-15.

Phase 1/2 study of glucocorticoid receptor (GR) antagonist mifepristone (MIFE) in combination with eribulin (E) in advanced solid tumors, with dose expansion in patients with GR-positive (GR+) triple-negative breast cancer (TNBC).

e12550Background: GR is highly expressed in TNBC and is associated with a poor prognosis in estrogen receptor-negative (ER-) early stage breast cancer. Treatment with MIFE potentiates the effects of chemotherapy (ctx) in TNBC xenografts. Here we describe the results of an ongoing trial including outcomes to date in all patients with GR+ TNBC treated at the recommended Phase 2 dose (RP2D). Objectives: To determine the safety, tolerability, pharmacokinetics (PK) and clinical activity of the MIFE+E combination in pts with GR+ TNBC at the RP2D. Methods: Eligibility: Phase 1, pts with solid tumors; Phase 2, pts with GR+ TNBC; up to 5 prior ctx regimens for advanced disease; ECOG PS 0-1; adequate end-organ function. Design: 3 + 3 dose escalation scheme. After a 7-day lead-in of oral daily MIFE alone, MIFE was continued daily and E was given on days 1 and 8 of a 21-day cycle. Results: 16 pts with metastatic breast cancer were enrolled in Phase 1 (3 with GR+ TNBC). MTD/RP2D was MIFE 300 mg/day + E 1.1 mg/m2. To d...

Immunocytochemical and stereological study of glucocorticoid receptors in rat medial vestibular nucleus neurons and the effects of unilateral vestibular deafferentation

Conclusion. The results of this study suggest that neither the number of medial vestibular nucleus (MVN) neurons expressing cytosolic glucocorticoid receptors nor blood corticosterone levels change significantly during the development of vestibular compensation. Objective. Vestibular compensation is a process of partial behavioral recovery that occurs following damage to the vestibular labyrinth. It has been suggested that this compensation process might be dependent on the release of glucocorticoids such as corticosterone at the time of unilateral vestibular deafferentation (UVD) and that changes in glucocorticoid receptors in the MVN might contribute to the initiation of the compensation process. Material and methods. We compared the number of MVN neurons expressing cytosolic glucocorticoid receptors in rats at 10 h and 2 weeks following UVD, and in sham and anesthetic control animals; we also measured blood corticosterone levels. Results. Using immunocytochemistry and stereology, we found that the majority of MVN neurons expressed glucocorticoid receptors, but there were no significant differences in the number of glucocorticoid receptor-expressing neurons in the ipsilateral or contralateral MVNs at 10 h or 2 weeks post-UVD; furthermore, corticosterone levels did not vary significantly between the UVD and control groups.

All of the Protein Interactions That Link Steroid Receptor·Hsp90·Immunophilin Heterocomplexes to Cytoplasmic Dynein Are Common to Plant and Animal Cells

Both plant and animal cells contain high molecular weight immunophilins that bind via tetratricopeptide repeat (TPR) domains to a TPR acceptor site on the ubiquitous and essential protein chaperone hsp90. These hsp90-binding immunophilins possess the signature peptidylprolyl isomerase (PPIase) domain, but no role for their PPIase activity in protein folding has been demonstrated. From the study of glucocorticoid receptor (GR).hsp90.immunophilin complexes in mammalian cells, there is considerable evidence that both hsp90 and the FK506-binding immunophilin FKBP52 play a role in receptor movement from the cytoplasm to the nucleus. The role of FKBP52 is to target the GR.hsp90 complex to the nucleus by binding via its PPIase domain to cytoplasmic dynein, the motor protein responsible for retrograde movement along microtubules. Here, we use rabbit cytoplasmic dynein as a surrogate for the plant homologue to show that two hsp90-binding immunophilins of wheat, wFKBP73 and wFKBP77, bind to dynein. Binding to dynein is blocked by competition with a purified FKBP52 fragment comprising its PPIase domain but is not affected by the immunosuppressant drug FK506, suggesting that the PPIase domain but not PPIase activity is involved in dynein binding. The hsp90/hsp70-based chaperone system of wheat germ lysate assembles complexes between mouse GR and wheat hsp90. These receptor heterocomplexes contain wheat FKBPs, and they bind rabbit cytoplasmic dynein in a PPIase domain-specific manner. Retention by plants of the entire heterocomplex assembly machinery for linking the GR to dynein implies a fundamental role for this process in the biology of the eukaryotic cell.

Molecular dynamics study of glucocorticoid receptor-DNA binding.

Molecular dynamics simulations have been conducted to investigate the binding of the glucocorticoid receptor (GR) dimer to DNA. For this purpose simulations of the complex formed by a DNA segment and a dimer of GR-DNA binding domains (GR-DBD) have been carried out, employing an available X-ray structure. A second set of simulations was based on this structure as well, except that the DNA segment was altered to the consensus glucocorticoid response element (GRE). Simulations of a single GR-DBD and of the uncomplexed GRE served as controls. For the simulations, each system was encapsulated in an ellipsoid of water. Protein-DNA interactions, dimer interactions, and DNA structural parameters were analyzed for each system and compared. The consensus GRE is found to yield more favorable and symmetric interactions between the GR-DBDs and the GRE, explaining the ability of the GR dimer to recognize this DNA segment. Further analysis focused on deformations of the DNA that are induced by the binding of GR. The deformations observed involve a 35 degree bend of the DNA, an unwinding, and a displacement of the helical axis. These deformations are consistent with a mechanism for transcriptional regulation that involves a change of nucleosome packing upon GR binding. Significant protein-protein and protein-DNA interactions, both direct and water mediated, develop due to the deformations of the GRE and are indicative of an increased recognition achieved through DNA deformation. The interactions include direct interactions between the GRE and glycine-458 and serine-459, side groups which differentiate GR from other members of the nuclear hormone receptor family.

Glucocorticoid receptors predict response to combination chemotherapy in patients with acute lymphoblastic leukemia.

Glucocorticoid receptor levels were quantified in leukemic blasts from peripheral blood of 86 patients with acute lymphoblastic leukemia. Subsequent achievement of complete remission correlated with high receptor levels. Forty-seven of 50 patients with leukemic cells containing more than 6,000 receptor sites and 22 of 36 patients with cells containing less than 6,000 receptor sites achieved remission. The study of glucocorticoid receptors in leukemic cells may predict response to combination chemotherapy in acute lymphoblastic leukemia patients.

Cortisol resistance in man.

Primary cortisol resistance in man is a familial disease characterized by increased plasma cortisol concentrations, high urinary free cortisol excretion, a normal circadian pattern of cortisol secretion, resistance to adrenal suppression by dexamethasone and absence of the clinical stigmata of Cushing's syndrome or signs of adrenal insufficiency. In its severe form, hypertension and hypokalemic alkalosis are present, owing to increased secretion of the sodium-retaining corticoids, corticosterone and deoxycorticosterone. In subjects with a less severe resistance to cortisol, there are no clinical abnormalities and the disease is revealed only by detailed examination of several parameters of cortisol metabolism or by glucocorticoid receptor studies. In whole-cell glucocorticoid receptor assays (peripheral mononuclear leukocytes, fibroblasts, or B-lymphocytes transformed with the Epstein-Barr Virus) low receptor affinity for dexamethasone could be demonstrated conclusively only in the severely affected subject. When affected cells are transformed with the Epstein-Barr virus, receptor induction is less than that of normal cells. The decreased affinity of the receptor for its ligand is reflected in an increased rate of loss of specific bound ligand during thermal activation. The molecular weight of the receptor, determined by SDS-PAGE, is similar to that from normal cells (approximately 92,000). Only in the severely affected patient was the proportion of activated receptor remaining in the cytosol of thermally activated intact cells reduced. At saturating concentrations of dexamethasone, nuclear binding appears normal in cells from both the severe and the asymptomatic forms of this condition, providing an explanation for the apparently complete compensation of the target tissue resistance to glucocorticoids by the high plasma cortisol levels. The clinical manifestations of the disorder (hypertension, hypokalemia) can be corrected with high doses of dexamethasone (3mg/day).

Cortisol 21-mesylate exerts glucocorticoid action on the induction of milk protein synthesis in cultured mammary gland.

Cortisol 21-mesylate, an alkylating derivatives of cortisol, was previously shown to exert an anti-glucocorticoid action in rat hepatoma cell culture (Simons, Thompson and Johnson 1980). In this study the effect of cortisol 21-mesylate on milk protein synthesis induced in cultured mouse mammary gland by glucocorticoid, insulin, and prolactin was investigated. Addition of cortisol 21-mesylate at concentrations ranging from 10(-8) M to 10(-6) M produced no inhibition of casein synthesis that was induced by glucocorticoid, insulin and prolactin in mammary explants from midpregnant mice. On the other hand, cortisol 21-mesylate in combination with insulin and prolactin stimulated casein synthesis in cultured tissue. The potency of cortisol mesylate was about 1/10 to 1/30th of that of cortisol. Cortisol 21-mesylate, like cortisol, also augmented the accumulation of alpha-lactalbumin in midpregnant rat mammary tissue cultured in the presence of insulin and prolactin. A cell-free competition study of glucocorticoid receptors using cytoplasmic extracts from mouse mammary tissue showed that cortisol 21-mesylate competitively inhibited the binding of dexamethasone on glucocorticoid receptors. The apparent affinity of cortisol 21-mesylate for glucocorticoid receptors is about 1/10th of that of cortisol. These results indicate that cortisol 21-mesylate acts as a glucocorticoid but not as an antiglucocorticoid in the mammary gland.

A study of glucocorticoid receptors in intracranial tumors.

Tissue samples from 20 patients with various intracranial tumors and one case of cerebral contusion were analyzed for the cytosolic glucocorticoid-receptor concentration using isoelectric focusing in slabs of polyacrylamide gel. It is pointed out that the clinical response to dexamethasone in brain edema associated with various intracranial lesions is, to some extent, parallel to the glucocorticoid-receptor concentration in these tumors. The findings in this investigation suggest that the cytosolic glucocorticoid receptor might be responsible for the initiation of a series of biochemical effects of steroids affecting brain edema. It is possible that the first step in eliciting a beneficial clinical response to dexamethasone in patients with brain tumors is the formation of a steroid-receptor complex in the peripheral parts of the tumor.