Glucocorticoid receptor in prostate epithelia is not required for corticosteroid-induced epithelial hyperproliferation in the mouse prostate

Differential effects of omega-3 PUFAS on tumor progression at early and advanced stages in TRAMP mice

BACKGROUND

In vitro studies evidenced antitumor effects of omega-3 polyunsaturated fatty acids ([n-3] PUFAs), but their effects on prostate cancer (PCa) remain controversial in epidemiological studies. Here we investigated whether an (n-3) PUFA-enriched diet affects tumor progression in transgenic adenocarcinoma of the mouse prostate (TRAMP), at early (12 weeks age) and advanced stages (20 weeks age).

METHODS

TRAMP mice were fed with standard rodent diet (C12, C20) or (n-3) PUFA-enriched diet containing 10% fish oil (T12, T20). A group of 8 weeks age animals fed standard diet was also used for comparison (C8). The ventral prostate was processed for histopathological and immunohistochemical analyses and serum samples submitted to biochemical assays.

RESULTS

At early stages, (n-3) PUFA increased the frequency of normal epithelium (3.8-fold) and decreased the frequency of high-grade intraepithelial neoplasia (3.3-fold) and in situ carcinoma (1.9-fold) in the gland, maintaining prostate pathological status similar to C8 group. At advanced stages, 50% of the animals developed a large primary tumor in both C20 and T20, and tumor weight did not differ (C20: 2.2 ± 2.4; T20: 2.8 ± 2.9 g). The ventral prostate of T12 and of T20 animals that did not develop primary tumors showed lower cell proliferation, tissue expressions of androgen (AR) and glucocorticoid (GR) receptors, than their respective controls. For these animals, (n-3) PUFA also avoided an increase in the number of T-lymphocytes, collagen fibers, and αSMA immunoreactivity, and preserved stromal gland microenvironment. (n-3) PUFA also lowered serum triglycerides and cholesterol, regulating the lipid metabolism of TRAMP mice.

CONCLUSIONS

(n-3) PUFAs had a protective effect at early stages of PCa, delaying tumor progression in TRAMP mice, in parallel with reductions in cell proliferation, AR, and GR and maintenance of the stromal compartment of the gland. However, (n-3) PUFAs did not prevent the development of primary tumors for the T20 group, reinforcing the need for further investigation at advanced stages of disease.

Strength Training Modulates Prostate of Wistar Rats Submitted to High-Fat Diet

Our aim is to evaluate the effects of high-fat diet and strength training on ventral prostate health through investigations of rat prostate histology, endocrine modulation, and the expression of proliferative and apoptotic marker, including androgen receptors (AR), glucocorticoid receptors (GR), B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X protein (BAX), Fas cell surface death receptor (Fas/CD95/Apo-1), and Nuclear Factor Kappa-B (NF-κB). Eighty Wistar rats were into one of four subgroups: control (CT), strength training (ST), high-fat diet consumption (HF), and high-fat diet consumption with strength training (HFT). Animals then underwent strength training and/or high-fat diet consumption for 8 or 12 weeks, after which animals were euthanized and markers of prostatic health were evaluated histologically and through immunolabeling. Our results indicate that physical strength training reduced the expression of the prostate cell proliferation marker Bcl-2 while increasing expression of the pro-apoptotic marker BAX, as well as increasing expression of AR and GR relevant in the Bcl-2 pathway. We conclude that a high-fat diet can alter hormone receptor levels and cell-cycle protein expression, thereby modifying prostatic homeostasis, and that strength training was able to reduce prostate damage induced by high-fat diet consumption.

Glucocorticoid Signaling in Health and Disease: Insights From Tissue-Specific GR Knockout Mice

Glucocorticoids are adrenally produced hormones critically involved in development, general physiology, and control of inflammation. Since their discovery, glucocorticoids have been widely used to treat a variety of inflammatory conditions. However, high doses or prolonged use leads to a number of side effects throughout the body, which preclude their clinical utility. The primary actions of glucocorticoids are mediated by the glucocorticoid receptor (GR), a transcription factor that regulates many complex signaling pathways. Although GR is nearly ubiquitous throughout the body, glucocorticoids exhibit cell- and tissue-specific effects. For example, glucocorticoids stimulate glucose production in the liver, reduce glucose uptake in the skeletal muscle, and decrease insulin secretion from the pancreatic β-cells. Mouse models represent an important approach to understanding the dynamic functions of GR signaling in normal physiology, disease, and resistance. In the absence of a viable GR null model, gene-targeting techniques utilizing promoter-driven recombination have provided an opportunity to characterize the tissue-specific actions of GR. The aim of the present review is to describe the organ systems in which GR has been conditionally deleted and summarize the functions ascribed to glucocorticoid action in those tissues.

Glucocorticoids and Reproduction: Traffic Control on the Road to Reproduction

Glucocorticoids are steroid hormones that regulate diverse cellular functions and are essential to facilitate normal physiology. However, stress-induced levels of glucocorticoids result in several pathologies including profound reproductive dysfunction. Compelling new evidence indicates that glucocorticoids are crucial to the establishment and maintenance of reproductive function. The fertility-promoting or -inhibiting activity of glucocorticoids depends on timing, dose, and glucocorticoid responsiveness within a given tissue, which is mediated by the glucocorticoid receptor (GR). The GR gene and protein are subject to cellular processing, contributing to signaling diversity and providing a mechanism by which both physiological and stress-induced levels of glucocorticoids function in a cell-specific manner. Understanding how glucocorticoids regulate fertility and infertility may lead to novel approaches to the regulation of reproductive function.

Corticosterone influences gerbil (Meriones unguiculatus) prostatic morphophysiology and alters its proliferation and apoptosis rates

Glucocorticoids (GCs) are hormones that are widely used in medicine; but although side effects are generally recognised, little is known about the precise mechanisms that is implicated in many of these side effects. Furthermore, GCs are highly correlated with stress and behaviour disorders. This study evaluated the effects of the glucocorticoid corticosterone on the ventral prostate of the Mongolian gerbil. Male gerbils (Meriones unguiculatus) (n = 5) received intraperitoneal injections of saline or corticosterone in doses of 0.5 mg/kg/day and 1.5 mg/kg/day for 5 days; while some of the animals were killed immediately after the treatment, the others were killed 5 days after the treatment period. The data show that corticosterone influences the structure and functionality of this organ. This hormone has anti-proliferative and anti-apoptotic properties in the prostate. In addition, the frequencies of the androgen (AR), oestrogen (ERα, ERβ) and glucocorticoid (GR) receptors changed. The frequencies of AR, GR and ERβ decreased in the Ct1/5 group; in the groups with rest period, the frequencies of GR increased and ERβ decreased in the epithelium. Changes in the proliferative index, apoptotic index and receptor activity may have contributed to the emergence of prostatic morphological alterations, such as the presence of cellular debris and inflammatory cells. Different doses of corticosterone had variable effects on the prostate, with a higher dose showing subtler effects and a lower dose showing more striking effects. The corticosterone effects on nuclear receptors were reverted or attenuated after a rest period, which was not observed for proliferation and apoptosis. In summary, we have demonstrated that corticosterone might influence the prostatic morphophysiology and that these changes may be linked in some way to the altered receptor distribution.

The role of glucocorticoid receptor in prostate cancer progression: from bench to bedside

Glucocorticoids are a common class of adjuvant drugs for the treatment of castration-resistant prostate cancer (CRPC) combined with antitumour or antiandrogen agents. Glucocorticoids are administered clinically because they ameliorate toxic side effects and have inhibitory effects on adrenal androgen production, acting as a pituitary suppressant. However, their effects on prostate cancer cells especially the castration resistance prostate cancer cells are poorly defined. Glucocorticoids exert effects depend to a great extent on glucocorticoid receptor. In addition to a number of glucocorticoid receptor isoforms determined, it is found that the actions of glucocorticoids through GRα are influenced by other isoforms, such as GRβ and GRγ. Recently, studies found GR confers resistance to androgen deprivation therapy, and various glucocorticoids exert distinct efficacy in CRPC. In this review, we summarized the mechanisms of glucocorticoids and its clinical appliances on the basis of present evidence.