Novel Insights into the Role of the Mineralocorticoid Receptor in Human Glioblastoma

The multifaceted role of the mineralocorticoid receptor in cancers

The mineralocorticoid receptor (MR/NR3C2) is a member of the family of steroid receptors (SR) which also includes the estrogen receptor (ER), progesterone receptor (PR), androgen receptor (AR) and glucocorticoid receptor (GR). They function primarily as nuclear receptors to regulate gene expression. While the other steroid hormone receptors are known to play important roles in the pathogenesis and progression of many cancers, relatively little is understood about the role of MR in cancer biology. This review focuses on examining new insights into the potential roles and mechanisms of action of MR in cancers.

Heart failure pharmacotherapy and cancer: pathways and pre-clinical/clinical evidence

Heart failure (HF) patients have a significantly higher risk of new-onset cancer and cancer-associated mortality, compared to subjects free of HF. While both the prevention and treatment of new-onset HF in patients with cancer have been investigated extensively, less is known about the prevention and treatment of new-onset cancer in patients with HF, and whether and how guideline-directed medical therapy (GDMT) for HF should be modified when cancer is diagnosed in HF patients. The purpose of this review is to elaborate and discuss the effects of pillar HF pharmacotherapies, as well as digoxin and diuretics on cancer, and to identify areas for further research and novel therapeutic strategies. To this end, in this review, (i) proposed effects and mechanisms of action of guideline-directed HF drugs on cancer derived from pre-clinical data will be described, (ii) the evidence from both observational studies and randomized controlled trials on the effects of guideline-directed medical therapy on cancer incidence and cancer-related outcomes, as synthetized by meta-analyses will be reviewed, and (iii) considerations for future pre-clinical and clinical investigations will be provided.

Protective role of mineralocorticoid receptor signaling in urothelial tumorigenesis

The expression status of mineralocorticoid receptor (MR) and its biological significance in human urothelial carcinoma remain unknown. The present study aimed to determine the functional role of MR in the development of urothelial cancer. In human normal urothelial SVHUC cells with exposure to a chemical carcinogen 3-methylcholanthrene (MCA), we assessed the effects of a natural MR ligand, aldosterone, and 3 MR antagonists, including spironolactone, eplerenone, and esaxerenone, as well as knockdown of MR via shRNA virus infection, on their neoplastic/malignant transformation. The in vitro system with carcinogen challenge showed that aldosterone and anti-mineralocorticoids significantly prevented and promoted, respectively, the neoplastic transformation of SVHUC cells. Similarly, MR knockdown in SVHUC cells considerably induced MCA-mediated neoplastic transformation, compared with a control subline. In addition, MR knockdown or antagonist treatment resulted in increases in the expression of β-catenin, c-Fos, and N-cadherin, and a decrease in that of E-cadherin. Meanwhile, spironolactone, which is known to possess anti-androgenic activity, rather suppressed the neoplastic transformation of a SVHUC subline stably expressing wild-type androgen receptor, indicating its dominant effect via the androgen receptor pathway. Immunohistochemistry in surgical specimens detected MR signals in 77 (98.7%; 23.1% weak/1+, 42.3% moderate/2+, and 33.3% strong/3+) of 78 non-invasive bladder tumors, which was significantly (P<0.001) lower than in adjacent non-neoplastic urothelial tissues (100%; 20.5% 2+ and 79.5% 3+). Moreover, the risks for disease recurrence after transurethral surgery were marginally lower in female patients with MR-high (2+/3+) tumor (P=0.068) and significantly lower in all patients with MR-high/glucocorticoid receptor-high tumor (P=0.025), compared with respective controls. These findings suggest that MR signaling functions as a suppressor for urothelial tumorigenesis.

Glucocorticoid Effects on Proteoglycans and Glycosaminoglycans

Glucocorticoids are steroid hormones that play diverse roles in numerous normal and pathological processes. They are actively used to treat a wide variety of diseases, including neurodegenerative and inflammatory diseases, cancers, and COVID-19, among others. However, the long-term use of glucocorticoids is associated with numerous side effects. Molecular mechanisms of these negative side effects are not completely understood. Recently, arguments have been made that one such mechanisms may be related to the influence of glucocorticoids on O-glycosylated components of the cell surface and extracellular matrix, in particular on proteoglycans and glycosaminoglycans. The potential toxic effects of glucocorticoids on these glycosylated macromolecules are particularly meaningful for brain physiology because proteoglycans/glycosaminoglycans are the main extracellular components of brain tissue. Here, we aim to review the known effects of glucocorticoids on proteoglycan expression and glycosaminoglycan content in different tissues, with a specific focus on the brain.

Spironolactone Induces Apoptotic Cell Death in Human Glioblastoma U87-MG Cancer Cells

Background: Spironolactone is a conventional drug widely in use for the treatment of heart failure and hypertension patients. On the other side recent studies have reported spironolactone can prevent growth and drug resistance in cancer stem cells (CSCs), by inhibiting DNA double-strand break (DSB) repair; suggesting its potential application in cancer therapy. Objectives: Our study aimed at assessing the potential cytotoxicity of spironolactone in human U87-MG glioblastoma cells. Methods: Different concentrations of spironolactone (0 - 50 μM) for 48 and 72 h were used for treatment. Cell viability assay was carried out by the 4, 5-dimethylthiazole-2-yl, 2, 5-diphenyl tetrazolium (MTT) method. Apoptosis was evaluated using annexin V/PI staining and flow cytometry and colorimetric measurement of caspase 8 and 9 activity. Results: Our findings showed a significant dose-dependent cytotoxic effect of spironolactone with maximum effect in 30 μM (P-value < 0.05). Spironolactone can induce approximately 20% apoptotic cell death in U87-MG cancer cells which were mainly related to early apoptotic cells. Indeed, the activity of caspase 8 and 9 was significantly elevated in spironolactone-treated cells compared to mock control. Conclusions: Findings showed the cytotoxic effect of spironolactone in U87-MG glioblastoma cancer cells in a mechanism dependent on apoptosis cell death induction. Our findings suggest the potential application of spironolactone in the treatment of glioblastoma in vitro.