DHEA supplementation to dexamethasone-treated rabbits alleviates oxidative stress in kidney-cortex and attenuates albuminuria

Molecular mechanism underlying cardioprotective effect of dehydroepiandrosterone on endoplasmic reticulum stress induced apoptosis in human vascular smooth muscle cells and human umbilical vein endothelial cells

Introduction

This study aimed to investigate the underlying mechanisms involved in the cardioprotective effects of dehydroepiandrosterone (DHEA) on endoplasmic reticulum stress (ERS) -mediated apoptosis in human vascular smooth muscle cells (HVSMCs) and human umbilical vein endothelial cells (HUVECs).

Material and methods

Various concentrations of Dithiothreitol (DTT) were used to induce ERS-mediated apoptosis. DHEA was utilized to inhibit the apoptotic effects of DTT, while estrogen receptor (ER) antagonists ICI 182,780 and G15, the androgen receptor (AR) antagonist flutamide and the aromatase inhibitor letrozole were used to identify the receptors activated during DHEA treatment in HVSMCs and HUVECs. Flow cytometry assessed the apoptotic rate, and Western blotting analysis evaluated the expression levels of ERS-related proteins GRP78 and PERK, and the apoptotic protein marker CHOP. Furthermore, the primary receptor signaling pathways were identified using signaling pathway blockers: LY294002 (PI3K blocker), SP600125 (JNK blocker), and U0126 (ERK1/2 blocker).

Results

In the DTT pretreatment group (0.8 mmol/L, for 8 h), the expressions of GRP78 and CHOP were significantly up regulated, indicating that an optimal ERS model was successfully established. Additionally, 10-4 mmol/L DHEA significantly inhibited the DTT-induced upregulation of GRP78 and CHOP. The results also demonstrated that the apoptotic rate in the DTT group was increased, while DHEA significantly reduced this rate. The addition of ER antagonists ICI 182,780 and G15 to HVSMCs reversed the effects of DHEA; however, the aromatase inhibitor letrozole and the AR antagonist flutamide did not reverse this effect. Notably, the use of the JNK inhibitor SP600125, the PI3K inhibitor LY294002, and the ERK1/2 inhibitor U0126 antagonized the protective effects of DHEA, with SP600125 showing the most significant impact on both HVSMCs and HUVECs.

Conclusion

Our study has identified a novel mechanism underlying the cardioprotective effects of DHEA. Specifically, DHEA may mitigate ERS-induced cell apoptosis by activating estrogen receptors ERα, ERβ, and GPER via the activated JNK pathway.

G6PD promotes cell proliferation and dexamethasone resistance in multiple myeloma via increasing anti-oxidant production and activating Wnt/β-catenin pathway

Background

Glucose-6-phosphate dehydrogenase (G6PD) as the rate-limiting enzyme in the pentose phosphate pathway (PPP) is well-established as an aberrantly expressed protein in numerous clinical diseases; however, its role in cancer, specifically in multiple myeloma (MM) remains elusive.

Methods

In this study, serum metabolites in 70 normal people and 70 newly diagnosed MM patients were analyzed using untargeted metabolomics and the results were verified using ELISA. The survival analysis of multiple clinical datasets was performed to identify a potential target gene in MM. The oncogenic role of G6PD was investigated using lentivirus-based overexpression or knockdown of G6PD using RNAi or an inhibitor in vitro, and in a xenograft mouse model in vivo. The mechanisms of induced Dexamethasone (Dexa)-resistance of G6PD were further explored using the above established MM cell lines in vitro.

Results

Based on the screening of potential genes, PPP was shown to be involved in the occurrence of MM, which was evidenced by the differential expression of serum metabolites of G6P and Dehydroepiandrosterone sulfate (DHEAS, the more stable sulfate ester form of an endogenously uncompetitive G6PD inhibitor known as DHEA). Elevated G6PD promoted MM cell proliferation. Mechanistically, high G6PD expression enhanced enzymatic generation of the antioxidant NADPH via the PPP and decreased the production of reactive oxygen species (ROS), thus inducing the proliferation and Dexa resistance in MM cells. Furthermore, canonical Wnt/β-catenin signaling also participated in regulating G6PD-induced drug resistance and cellular redox levels of ROS. Intriguingly, DHEA treatment could enhance the sensitivity of MM cells to Dexa primarily through augmenting cellular oxidative stress.

Conclusions

Our data demonstrate that G6PD enhances the generation of the enzymatic anti-oxidant NADPH and decreases ROS generation, thereby promoting resistance to Dexa-induced apoptosis via the enzymatic PPP and non-enzymatic Wnt/β-catenin signaling pathway in MM. Targeting G6PD to harness cellular redox may serve as a promising novel strategy for the management of MM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40164-022-00326-6.

Correlation of DHEA with diabetic nephropathy and its clinical value in early detection

Aims/Introduction

This study was carried out to assess the association of dehydroepiandrosterone (DHEA) with diabetic nephropathy (DN) in patients with type 2 diabetes mellitus to better predict the progression of diabetic nephropathy.

Materials and Methods

A total of 1,082 patients with type 2 diabetes mellitus in the Department of Endocrinology and Metabolism of Tianjin Medical University General Hospital were enrolled in this study, and grouped for comparison. The effect of serum DHEA on DN was evaluated by multivariate logistic regression analysis, and receiver operating characteristic curves were established to explore the optimal concentration of DHEA in patients with DN and non‐DN.

Results

DHEA was significantly decreased in patients with DN (P < 0.001). The prevalence of DN was significantly higher in the low DHEA quartile than in the other quartiles (P < 0.001). Spearman‐related analysis showed that DHEA levels were negatively correlated with patient age, course of diabetes, systolic blood pressure, blood creatinine, uric acid, urine albumin‐to‐creatinine ratio, 24‐h urine microalbumin, 24‐h urine protein quantification and glomerular filtration rate, and positively correlated with body mass index, total cholesterol and low density lipoprotein. Logistic regression analysis showed that the effect of DHEA on DN was statistically significant (P < 0.001). The receiver operating characteristic curve showed that the sensitivity was 81.4%, the specificity was 70% and the area under the curve was 0.812 when the optimal cut‐off value was 1,640 (pg/mL).

Conclusion

DHEA is significantly associated with DN and might be a protective factor for DN, and is important for the prediction of DN.

Low Serum Dehydroepiandrosterone Is Associated With Diabetic Kidney Disease in Men With Type 2 Diabetes Mellitus

Background

The associations of dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) with diabetic kidney disease (DKD) remained unclear. Thus, this cross-sectional study aimed to explore the associations of DHEA and DHEAS with the risk of DKD in patients with T2DM.

Methods

The information of 1251 patients with T2DM were included in this study. Serum DHEA and DHEAS were quantified using liquid chromatography-tandem mass spectrometry assays. Multivariate logistic regression analyses were used to assess the associations of DHEA and DHEAS with DKD as well as high urine albumin to creatinine ratio (ACR).

Results

In men with T2DM, the risk of DKD decreased with an increasing DHEA concentration after adjustment for traditional risk factors; the fully adjusted OR (95% CI) for tertile3 vs tertile1 was 0.37 (0.19-0.70; P = 0.010 for trend). Similarly, when taking high ACR as the outcome, low DHEA levels were still significantly associated with increased odds of high ACR (OR, 0.37; 95% CI, 0.19-0.72 for tertile3 vs tertile1; P = 0.012 for trend). The restricted cubic spline showed that the risk of DKD gradually decreased with the increment of serum DHEA levels (P-overall = 0.007; P-nonlinear = 0.161). DHEAS was not independently associated with the risk of DKD in men. In contrast, no significant relationships were found between DHEA and DHEAS and the risk of DKD in women (all P > 0.05).

Conclusions

In men with T2DM, low serum DHEA levels were independently related to the risk of DKD after adjustment for traditional risk factors. Our finding highlights the potential role of DHEA in the development of DKD in men with T2DM.

Effect of dehydroepiandrosterone on atherosclerosis in postmenopausal women

In China, cardiovascular disease (CVD) has surpassed malignant tumours to become the disease with the highest mortality rate, and atherosclerosis (AS) is an important pathological cause of CVD. Dehydroepiandrosterone (DHEA) is the most abundant steroid hormone in circulating human blood and is a precursor of estrogen and androgen. DHEA is converted into a series of sex hormones in local peripheral tissues where its acts physiologically. DHEA also acts therapeutically, thereby avoiding the adverse systemic reactions to sex hormones. DHEA inhibits AS, thus inhibiting the development of CVD, and it improves the prognosis for CVD. The incidence of CVD in postmenopausal women is substantially higher than that in premenopausal women, and that incidence is believed to be related to a decrease in ovarian function. The current review analyzes the mechanisms of postmenopausal women's susceptibility to AS. They tend to have dyslipidemia, and their vascular smooth muscle cells (VSMCs) proliferate and migrate more. In addition, oxidative stress and the inflammatory response of endothelial cells (ECs) are more serious in postmenopausal women. This review also discusses how DHEA combats AS by countering these mechanisms, which include regulating the blood lipid status, protecting ECs (including coping with oxidative stress and inflammatory reactions of the vascular endothelium, inhibiting apoptosis of ECs, and inducing NO production) and inhibiting the proliferation and migration of VSMCs. As a result, DHEA has great value in preventing AS and inhibiting its progression in postmenopausal women.

In vitro and in vivo tenocyte-protective effectiveness of dehydroepiandrosterone against high glucose-induced oxidative stress

BACKGROUND

Dehydroepiandrosterone (DHEA), an adrenal steroid, has a protective role against diabetes. This study aimed to investigate the in vitro and in vivo protective effects of DHEA against high glucose-induced oxidative stress in tenocytes and tendons.

METHODS

Tenocytes from normal Sprague-Dawley rats were cultured in low-glucose (LG) or high-glucose (HG) medium with or without DHEA. The experimental groups were: control group (LG without DHEA), LG with DHEA, HG without DHEA, and HG with DHEA. Reactive oxygen species (ROS) production, apoptosis, and messenger RNA (mRNA) expression of NADPH oxidase (NOX) 1 and 4, and interleukin-6 (IL-6) were determined. Further, diabetic rats were divided into a control group and a DHEA-injected group (DHEA group). NOX1 and NOX4 protein expression and mRNA expression of NOX1, NOX4, IL-6, matrix metalloproteinase (MMP)-2, tissue inhibitors of matrix metalloproteinase (TIMP)-2, and type I and III collagens in the Achilles tendon were determined.

RESULTS

In rat tenocytes, DHEA decreased the expression of NOX1 and IL-6, ROS accumulation, and apoptotic cells. In the diabetic rat Achilles tendon, NOX1 protein expression and mRNA expression of NOX1, IL-6, MMP-2, TIMP-2, and type III collagen were significantly lower while type I collagen expression was significantly higher in the DHEA group than in the control group.

CONCLUSIONS

DHEA showed antioxidant and anti-inflammatory effects both in vitro and in vivo. Moreover, DHEA improved tendon matrix synthesis and turnover, which are affected by hyperglycemic conditions. DHEA is a potential preventive drug for diabetic tendinopathy.

DHEA-pretreatment attenuates oxidative stress in kidney-cortex and liver of diabetic rabbits and delays development of the disease

In view of reported discrepancies concerning antioxidant activity of dehydroepiandrosterone (DHEA), a widely used dietary supplement, the current investigation was undertaken to evaluate the antioxidant properties of DHEA in both kidney-cortex and liver of alloxan (ALX)-induced diabetic rabbits, as this diabetogenic compound exhibits the ROS-dependent action. ALX was injected to animals following 7 days of DHEA administration. Four groups of rabbits were used in the experiments: control, DHEA-treated control, diabetic and DHEA-treated diabetic. Our results show for the first time, that in kidney-cortex DHEA resulted in normalization of hydroxyl free radicals (HFR) levels and restoration of catalase (CAT) and glutathione peroxidase (GPx) activities to near the control values, while in liver DHEA prevented the malondialdehyde (MDA) accumulation and normalized glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PDH) activities. Moreover, in both kidney-cortex and liver DHEA supplementation prevented GSSG elevation accompanied by a decrease in GSH/GSSG ratio. Although DHEA attenuated oxidative stress in both kidney-cortex and liver of ALX-induced diabetic rabbits and significantly delayed the onset of diabetes in time, it did not protect against the final development of diabetes. In conclusion, the current investigation underscores the complexity of the antioxidant action of DHEA. The data are of clinical interest since DHEA supplementation could prevent the deleterious effects of ROS and delay, or even prevent the onset of many diseases. However, in view of the reported pro-oxidant effects of high DHEA doses, the potential use of this agent as a supplement needs a careful evaluation.

Dexamethasone upregulates mitochondrial Tom20, Tom70, and MnSOD through SGK1 in the kidney cells

Dexamethasone augments mitochondrial protein abundance. The translocase of the outer membrane (Tom) of mitochondria plays a major role in importing largely cytosolically synthesized proteins into mitochondria. We hypothesize that dexamethasone upregulates the Tom transport system, leading to increase of mitochondrial protein localization. Tom20 and Tom70 are the two major subunits. Dexamethasone increased Tom20 and Tom70 mRNA levels by 53 ± 11% and 25 ± 9% and mitochondrial protein abundance by 27 ± 7% and 25 ± 4% (p < 0.05 for all), respectively, in HEK293 cells. In parallel, dexamethasone elevated the SGK1 mRNA by 79 ± 17% and activity by 190 ± 42%, and mitochondrial protein level by 41 ± 2% (all p < 0.05) without significantly affecting the cytosol counterpart. The discovery of the effect of dexamethasone on SGK1 protein restricted in the mitochondria attracted us to examine the effect of the hormone on MnSOD, an enzyme with known mitochondrial localization and function. Similarly, dexamethasone significantly increased MnSOD transcripts by 67 ± 15% and protein level only in the mitochondria dose-dependently. Inhibition of SGK1 by GSK650394 and RNAi significantly attenuated the effects of the hormone on Tom20, Tom70, and MnSOD, indicating that SGK1 relays the effects of dexamethasone. Catalase inhibited the effects of dexamethasone on SGK1 and the subsequent effects of SGK1 on Tom20, Tom70, and MnSOD. Finally, knock-down of Tom20 and Tom70 by their siRNAs reduced dexamethasone-induced increases in the mitochondrial localization of SGK1 and MnSOD proteins. In conclusion, dexamethasone upregulates Tom20, Tom70, and MnSOD, and these effects are dependent on reactive oxygen species and SGK1. Dexamethasone-induced increases of SGK1 and MnSOD mitochondrial localization requires Tom20 and Tom70.

Long-term supplementation of dehydroepiandrosterone improved depressive-like behaviors by increasing BDNF expression in the hippocampus in ovariectomized rats

Objective

Dehydroepiandrosterone (DHEA), a precursor of estrogen, partially exhibits its biological effect after conversion to estrogen. Its biological significance in perimenopausal depressive disorder or postpartum depression remains unknown. Here, we observed the effects of long-term supplementation of DHEA on depression-like behaviors in ovariectomized rats.

Methods

We established the model as one of sex hormone deficiency in female rats by bilateral ovariectomy. We observed the effects of 13.3 mg/kg DHEA or 0.27 mg/kg estradiol were given daily by gavage for 12 weeks on lipid metabolism, glucose tolerance, and depression-like behaviors in ovariectomized rats. Furthermore, the expression of brain-derived neurotrophic factor (BDNF) and its signaling molecule in the hippocampus was analyzed.

Results

The 12-week supplementation of DHEA or estradiol significantly alleviated weight gain and improved the glucose tolerance in the ovariectomized rats. Moreover, Long-term supplement of DHEA or estradiol significantly increased sucrose preference and locomotion activities, and reduced immobility duration of the ovariectomized rats in the water. Both DHEA and estradiol treatments increased the expression of BDNF, phosphorylation of ERK and CREB, and ERβ, but not that of ERα in the hippocampus of the ovariectomized rats.

Conclusions

Overall, chronic treatment with DHEA improved depression-like behaviors in ovariectomized rats, suggesting that it may be useful for the treatment of sex hormone deficiency such as perimenopausal depressive disorder or postpartum depression.

Dehydroepiandrosterone protects against hepatic glycolipid metabolic disorder and insulin resistance induced by high fat via activation of AMPK-PGC-1α-NRF-1 and IRS1-AKT-GLUT2 signaling pathways

BACKGROUND/OBJECTIVES

Mitochondrial dysfunction, oxidative stress, or fatty liver are the key pathophysiological features for insulin resistance and obesity. Dehydroepiandrosterone (DHEA) can ameliorate obesity and insulin resistance; however, the mechanisms of these actions are poorly understood. The present study aimed to investigate the effect and possible mechanism of DHEA against glycolipid metabolic disorder and insulin resistance.

SUBJECTS/METHODS

Rats fed a high-fat diet (HFD) and palmitic acid (PA)-induced BRL-3A cells were employed to analyze the effect of DHEA on factors related to metabolic disorder and insulin resistance in vivo and in vitro.

RESULTS

DHEA prevented lipid metabolism disorders by enhancing phospho (p)-protein kinase AMP-activated catalytic subunit alpha (AMPKα) (Thr172) protein level and its downstream lipid metabolism-related factors in liver of rats fed an HFD or in PA-induced BRL-3A cells. Meanwhile, DHEA ameliorated mitochondrial dysfunction through activation of the AMPK-peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α)-nuclear respiratory factor-1 (NRF-1) pathway, which represented as the enhancing of the mtDNA copy number, ATP level, and membrane potential, and decreasing of reactive oxygen species production. Moreover, DHEA alleviated insulin resistance via increasing the phosphorylated insulin receptor substrate 1 (p-IRS1) (Tyr612) level and decreasing that of p-IRS1 (Ser307) level in liver of rats fed an HFD or in PA-induced BRL-3A cells, which subsequently enhanced p-protein kinase B (AKT) (Ser473) and membrane glucose transporter type 2 (GLUT2) expression levels.

CONCLUSIONS

The protective effect of DHEA on high-fat-induced hepatic glycolipid metabolic disorder and insulin resistance are achieved through activation of the AMPK-PGC-1α-NRF-1 and IRS1-AKT-GLUT2 signaling pathways. The results provide compelling evidence for the mechanism by which DHEA prevents glycolipid metabolic disorder, and suggest its potential applications for controlling diabetes and obesity in animals and humans.