Immunohistochemical detection of angiotensin receptors AT1 and AT2 in adrenal tumors

Angiotensin II is well known to affect the adrenal cell growth and function. Angiotensin receptors AT1 and AT2 were found to be present in the normal adrenal gland. However, the data on the expression of the angiotensin receptors in the adrenal tumors are very scarce. To overcome this gap, the paraffin sections of the adrenal cortical tumors and of pheochromocytomas from the archival material were immunostained with antibodies raised against AT1 (sc-1173) and AT2 (sc-9040) receptor proteins. In hyperplasia of the adrenal cortex and in benign adrenocortical adenomas, both functioning and non-functioning, the AT1 immunostaining was present mainly in the cell membranes. A positive immunoreaction was also found in the subpopulation of cell nuclei and within the cytoplasm. In the adrenal cancer, as well as in pheochromocytomas, neither cell membranes nor cell nuclei were immunostained with anti-AT1 antibody. However, a weak AT1 immunostaining was present within the cytoplasm of tumoral cells. With anti-AT2 antibody, in all tumors investigated, the tumoral cells were immunonegative but moderate to strong AT2 immunostaining was observed in the walls of intratumoral blood vessels and in the interstitial tissue. Our data indicates that the expression of AT1 receptors is altered in adrenal cancer and in pheochromocytomas. The expression of AT2 receptors, in turn, may be connected with the process of tumoral neo-angiogenesis.     

Nuclear accumulation of fibroblast growth factor receptors is regulated by multiple signals in adrenal medullary cells.

In an effort to determine the localization of fibroblast growth factor (FGF) receptors (FGFR) that could mediate the intracellular action of FGF-2, we discovered the presence of high-affinity. FGF-2 binding sites in the nuclei of bovine adrenal medullary cells (BAMC). Western blot analysis demonstrated the presence of 103-, 118-, and 145-kDa forms of FGFR1 in nuclei isolated from BAMC. 125I-FGF-2 cross-linking to nuclear extracts followed by FGFR1 immunoprecipitation showed that FGFR1 can account for the nuclear FGF-2 binding sites. Nuclear FGFR1 has kinase activity and undergoes autophosphorylation. Immunocytochemistry with the use of confocal and electron microscopes demonstrated the presence of FGFR1 within the nuclear interior. Nuclear subfractionation followed by Western blot or immunoelectron microscopic analysis showed that the nuclear FGFR1 is contained in the nuclear matrix and the nucleoplasm. Agents that induce translocation of endogenous FGF-2 to the nucleus (forskolin, carbachol, or angiotensin II) increased the intranuclear accumulation of FGFR1. This accumulation was accompanied by an overall increase in FGF-2-inducible tyrosine kinase activity. Our findings suggest a novel mode for growth factor action whereby growth factor receptors translocate to the nucleus in parallel with their ligand and act as direct mediators of nuclear responses to cell stimulation.     

Nuclear planimetry in renal-cell tumors

A morphometric study using conventional planimetry was carried out in 73 renal-cell tumors (64 adenocarcinomas and 9 adenomas) in order to correlate the objective nuclear measurements with some histologic and clinical data believed to have prognostic value. The use of a discriminant function to correctly separate adenomas and low-grade adenocarcinomas was also investigated. There was a strong association between the nuclear grade and the following parameters: nuclear area, nuclear major diameter and nuclear elongation. There was also a relationship between an adverse outcome and the major nuclear diameter and nuclear elongation. In a univariate survival analysis, only the clinicopathologic stage, the nuclear grade and the histologic presence of a pseudosarcomatous cell population had predictive value. Multivariate survival analysis using Cox models showed that the clinicopathologic stage, major nuclear diameter, presence of anaplastic cells and nuclear area had predictive value. Although the minor nuclear diameter reached a significant level, a discriminant function that would correctly separate adenomas and low-grade renal-cell carcinomas could not be formulated.     

Steroid biosynthesis in human adrenal tumors

Patients with adrenal tumors present with varied clinical features which may be related to differing patterns of adrenal steroidogenesis. To explore the mechanism underlying these differences, we studied the in vitro activities of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), 17-hydroxylase (17-OH), 21-hydroxylase (21-OH), and 17-20 desmolase (17, 20-D) in 6 adrenal tumors, 4 adenomas and 2 carcinomas. Normal human adrenal tissue was also studied for comparison. Adrenal adenomas had increased 21-OH activity compared with normal adrenal tissue (11.4 +/- 0.7 vs 5.5 +/- 0.5 nmol/mg prot/min, P less than 0.002) and with adrenal carcinomas (11.4 +/- 0.7 vs 3.3 +/- 0.9 nmol/mg prot/min, P less than 0.001). Carcinomas had reduced 3 beta-HSD, 17-OH and 17,20-D activities when compared to controls, but this did not reach statistical significance. These observations suggest less efficient steroidogenesis by adrenal carcinomas, a finding which may explain the large size of these tumors when the symptoms of hypercortisolism first appear.     

Nuclear receptors in renal disease

Diabetes is the leading cause of end-stage renal disease in developed countries. In spite of excellent glucose and blood pressure control, including administration of angiotensin converting enzyme inhibitors and/or angiotensin II receptor blockers, diabetic nephropathy still develops and progresses. The development of additional protective therapeutic interventions is, therefore, a major priority. Nuclear hormone receptors regulate carbohydrate metabolism, lipid metabolism, the immune response, and inflammation. These receptors also modulate the development of fibrosis. As a result of their diverse biological effects, nuclear hormone receptors have become major pharmaceutical targets for the treatment of metabolic diseases. The increasing prevalence of diabetic nephropathy has led intense investigation into the role that nuclear hormone receptors may have in slowing or preventing the progression of renal disease. This role of nuclear hormone receptors would be associated with improvements in metabolism, the immune response, and inflammation. Several nuclear receptor activating ligands (agonists) have been shown to have a renal protective effect in the context of diabetic nephropathy. This review will discuss the evidence regarding the beneficial effects of the activation of several nuclear, especially the vitamin D receptor (VDR), farnesoid X receptor (FXR), and peroxisome-proliferator-associated receptors (PPARs) in preventing the progression of diabetic nephropathy and describe how the discovery and development of compounds that modulate the activity of nuclear hormone receptors may provide potential additional therapeutic approaches in the management of diabetic nephropathy. This article is part of a Special Issue entitled: Translating nuclear receptors from health to disease.     

核受体与脂质代谢

核受体是配体活化的转录因子,能调控大量的靶基因。近年来核受体调节脂质代谢的研究已成为国内外研究的热点。由于核受体在调节脂质代谢、糖代谢以及炎症反应方面发挥重要作用,它们是治疗心血管疾病理想的靶标。本文简要地介绍了核受体在调节脂质代谢方面的研究进展。     

Nuclear receptors and inflammatory diseases

It is well known that the steroid hormone glucocorticoid and its nuclear receptor regulate the inflammatory process, a crucial component in the pathophysiological process related to human diseases that include atherosclerosis, obesity and type II diabetes, inflammatory bowel disease, Alzheimer's disease, multiple sclerosis, and liver tumors. Growing evidence demonstrates that orphan and adopted orphan nuclear receptors, such as peroxisome proliferator-activated receptors, liver x receptors, the farnesoid x receptor, NR4As, retinoid x receptors, and the pregnane x receptor, regulate the inflammatory and metabolic profiles in a ligand-dependent or -independent manner in human and animal models. This review summarizes the regulatory roles of these nuclear receptors in the inflammatory process and the underlying mechanisms.     

Neurotrophins and their receptors in tumors

Neurotrophins are structurally related growth polypeptide factors that play an essential role in the development and functioning of the vertebrate nervous system. They provide forming and survival of different neuron populations of the central and peripheral nervous system. Neurotrophins are also involved in the processes of higher nervous activity. Neurotrophins are active not only in the nervous system; these universal trophic factors are important for the development, proliferation, and maintaining of different tissues including tumor tissues. Changes in the neurotrophin signaling system are significant for the pathogenesis of malignancies at the initiation stage as well as during the tumor progression. Neurotrophins and their receptors are complex multi-component system controlled in a very complicated manner. This system can affect the cells and tissues in different ways; the final results of neurotrophin action vary from cell maintenance and survival to apoptosis. Differences in mechanisms and results of the neurotrophin action depend on the cell and tissue type in which the system works. The effects of the neurotrophin signaling are especially variable in different malignancies. In the review we summarize the information on the neurotrophin signaling in various tumors and demonstrate its contribution to the disease course.     

Retroperitoneal masses mimicking adrenal tumors

ObjectiveTo report 10 cases of neoplasms that were initially thought to be primarily adrenal-derived masses but were later confirmed as tumors of a different origin.MethodsBetween 2000 and 2011, a total of 229 patients underwent adrenalectomy at our institution. Of this overall group, 10 patients had retroperitoneal pathologic conditions mimicking adrenal tumors. Using an institutional review board-approved database, we reviewed the clinical, biochemical, and radiologic characteristics of these 10 patients.ResultsThe study cohort consisted of 4 male and 6 female patients. The mean age of these 10 patients was 48 years. The pathologic conditions included schwannoma (n = 3), leiomyosarcoma (n = 2), and 1 each of metastatic angiosarcoma, metastatic granulosa cell tumor, retroperitoneal hematoma, perivascular epithelioid cell tumor, and bronchogenic cyst. The patient with angiosarcoma had elevated plasma and urine catecholamines and a positive metaiodobenzylguanidine scan, whereas the others had normal findings on biochemical work-up. A percutaneous biopsy was performed preoperatively in 2 patients.All patients, except the patient with hematoma, underwent abdominal exploration, which was laparoscopic in 5, open in 2, and robotic in 2. With exclusion of the patients with angiosarcoma and hematoma, resection was possible in all the remaining patients.ConclusionIn this report we describe our experience with retroperitoneal masses mimicking adrenal tumors. Increased awareness of these unusual pathologic conditions is important for appropriate clinical management of these tumors. The presentation of the patients and the surgical management of these individual pathologic entities are highlighted. (Endocr Pract. 2012;18:335-341)     

High-affinity angiotensin receptors in rat adrenal medulla

Angiotensin II receptors have been quantitated in single rat adrenal medullas by incubation of tissue sections with 125I-[Sar1]-AII, autoradiography with exposure to 3H-sensitive Ultrofilm, computerized densitometry and comparison with 125I-labelled standards. Rat adrenal medulla contains a single class of high affinity AII receptors with a Ka of 0.84 +/- 0.02 X 10(9) M-1 and a Bmax of 3259 +/- 502 fmol/mg protein, one of the highest densities in AII receptors found in rat tissues. These observations provide evidence for a local site of action of AII in the release of adrenal medullary catecholamines.     

Oestrogen receptors in the rat adrenal gland

Cytosol from the adrenal gland of male and female rats contains a specific binding protein for oestradiol-17β. This protein has all the characteristics of a cytoplasmic oestrogen receptor. It is excluded by Sephadex G-200 gel filtration, has a sedimentation coefficient of 8–9 S by sucrose density gradient centrifugation in low salt and dissociates into a 4 S form by centrifugation in high salt (0.5 M KCl). The binding protein is heat sensitive and oestradiol-17β binding is eliminated by protease and by sulphydryl blocking reagents (2mM p-chloromercuriphenylsulphonate). The bound oestradiol dissociates very slowly at 0°C. The adrenal oestrogen receptors have a very high affinity for oestradiol-17β, but lower affinity for oestradiol-17α and do not bind testosterone, androstene-3,17-dione or corticosterone. Scatchard analysis of the saturation data for oestradiol revealed one class of high affinity binding sites with an apparent equilibrium constant of dissociation K_D at 0°C of 5.8 × 10⁻¹⁰M. The number of binding sites was calculated to be 70 fmol/mg cytosol protein. Cytosol fractions from androgen insensitive (tfm) male rats contain oestrogen receptors in amounts very similar to that of the normal littermates.     

Cholinergic muscarinic receptors in bovine adrenal cortex

Crude membrane preparations from bovine adrenocortical tissue were shown to exhibit high affinity (Kd = 1.2 ± 0.25 nM) and limited capacity (Bsp = 67.2 ± 5.7 pmole ligand/g protein) binding sites for the muscarinic antagonist L-quinuclidinyl benzylate. Cometitive binding experiments confirmed that the binding activity had the characteristic of a cholinergic receptor of the muscarinic type. These findings which cannot be explained by a contamination from adrenal medullary tissue suggest that a cholinergic mechanism (muscarinic type) may be considered in the modulation of adrenocortical functions.     

Nuclear bodies in the normal and hyperfunctional human adrenal cortex

Adrenal pieces obtained from six female patients, three without increased adrenocortical function and three with Cushing's disease, showed, in all adrenal cortex zones, cells containing simple and complex nuclear bodies. The simple nuclear bodies were spherical or ovoid and had a filamentous structure surrounded by a clear halo. Complex nuclear bodies were more numerous and heterogeneous in patients with adrenal pathology, and they were spherical with a proteinaceous filamentous capsule surrounding a core; the core was granular, filamentous or a mixture of granular and filamentous material, sometimes with a reticular or concentric arrangement. Some bodies showed vacuolar or multilocular aspect, and others had a close relationship with the nucleolus or appeared near the interchromatin granules. The meaning of adrenal nuclear bodies is discussed as well as their relationship with ACTH stimulation.