Manganese Superoxide Dismutase Expression Research Articles

Oxidative Stress-regulating Enzymes and Endometrial Cancer Survival in Relation to Metformin Intake in Diabetic Patients.

Metformin inhibits tumorigenesis in endometrial carcinoma and interferes with the expression of oxidative stress-regulating proteins, such as nuclear factor erythroid 2-related factor 2 (Nrf2) and Kelch-like ECH-associated protein 1 (Keap1). Although manganese superoxide dismutase (MnSOD) is vital for withstanding mitochondrial oxidative stress, it has also been linked with chemoresistance and poorer outcomes in several cancer types. However, data on endometrial cancers are limited. This study aimed to highlight the relationship between mitochondrial redox regulation and endometrial cancer survival in relation to metformin consumption in women with type 2 diabetes mellitus (T2DM). Our retrospective hospital-based cohort study included 121 patients diagnosed with endometrial carcinoma and T2DM between 2007 and 2014. Fifty-eight patients were using metformin at the time of diagnosis. Nrf2 and Keap1 expression levels in the tumor samples were assessed immunohistochemically, and MnSOD levels were measured both immunohistochemically and from the serum samples. High MnSOD tissue expression was associated with better overall survival among metformin users in the univariate analysis (p=0.03). When adjusted for histology and stage, high serum MnSOD was associated with better overall survival (HR=0.22, 95%CI=0.07-0.71, p=0.01). No association was found between MnSOD, Nrf2, or Keap1 and overall survival among metformin non-users. Higher expression of MnSOD in patients with endometrial cancer and T2DM is associated with better overall survival if the patient is consuming metformin.

Heat stress suppresses MnSOD expression via p53-Sp1 interaction and induces oxidative stress damage in endothelial cells: Protective effects of MitoQ10 and Pifithrin-α

AimTo investigate the mechanism of p53-mediated suppression of heat stress-induced oxidative stress damage by manganese superoxide dismutase (MnSOD) in endothelial cells (ECs). MethodsPrimary ECs isolated from mouse aortas were used to examine the effects of heat stress on vascular ECs viability and apoptosis. We measured MnSOD expression, reactive oxygen species (ROS) production, p53 expression, viability, and apoptosis of heat stress-induced ECs. We also tested the protective effects of MitoQ10, a mitochondrial-targeted antioxidant, and Pifithrin-α, a p53 inhibitor, in ECs from a mouse model of heat stroke. ResultsHeat stress increased cellular apoptosis, ROS production, and p53 expression, while reducing cellular viability and MnSOD expression in ECs. We also showed that the suppression of MnSOD expression by heat stress in ECs was mediated by interactions between p53 and Sp1. Furthermore, MitoQ10 and Pifithrin-α alleviated heat stress-induced oxidative stress and apoptosis in ECs. ConclusionOur results revealed that p53-mediated MnSOD downregulation is a key mechanism for heat stress-induced oxidative stress damage in ECs and indicated that MitoQ10 and Pifithrin-α could be potential therapeutic agents for heat stroke.

CYP2E1 triggered GRP78/ATF6/CHOP signaling axis inhibit apoptosis and promotes progression of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the leading cause of cancer-related death worldwide. Cytochrome P450 2E1 (CYP2E1) is an enzyme, primarily involved in the metabolism of xenobiotics and procarcinogens. The present study was designed to investigate the potential role of CYP2E1 triggered endoplasmic reticulum stress in the progression of HCC through inhibition of apoptosis. In vitro CYP2E1 promotes HepG2 cell migration, reduced chromatin condensation, enhanced intracellular ROS accumulation and induce cell cycle progression. Conversely this effect was averted by CYP2E1 siRNA, selective inhibitor Diallyl sulphide (DAS) and antioxidants (vitamin C and E). In vivo Diethylnitrosamine (DEN) induced HCC rats showed decreased body weight and increased relative liver weight. Moreover, macro trabecular-massive HCC (MTM-HCC) histological subtyping showed pathological features like well-differentiated tumors, micro-trabecular and pseudo glandular patterns, megakaryocytes and cholestasis. Masson's trichrome staining revealed an intensive accumulation of collagen fibers in the extracellular matrix (ECM). Increased CYP2E1, VEGF and PCNA enhance the carcinogenicity as revealed in immunohistochemistry results. Immunoblot analysis showed reduced expression of copper-zinc superoxide dismutase (CuZnSOD) and manganese superoxide dismutase (MnSOD) in cytosolic as well as mitochondrial fraction of rat liver tissue respectively. Also, increased level of CYP2E1 stimulated the upregulation of unfolded proteins response (UPR) and ER stress-related proteins such as Glucose regulatory protein 78 (GRP78), activating transcription factor 6 (ATF6) and CCAAT enhancer-binding protein (C/EBP) homologous protein (CHOP). Meanwhile, CYP2E1 stimulated ER-stress reduces BCL2 and downregulates the cleaved caspase 3 thus suppresses apoptosis. in. Furthermore, immunofluorescence revealed increased expression level of α-SMA in the HCC rat liver tissue. The level of CYP2E1 mRNA was significantly increased. Altogether, these findings indicate that CYP2E1 has a dynamic role in the pathogenesis of HCC and might be a budding agent in liver carcinogenesis therapy.

Honokiol reduces oxidative stress by activating the SIRT3-MnSOD2 pathway to alleviate hypertriglyceridemia-induced acute pancreatitis in rats

To determine how honokiol affects the sirtuin-3 (SIRT3)-MnSOD2 pathway and oxidative stress in rats with hypertriglyceridemia-induced acute pancreatitis (HTGP). Thirty 4-week-old male SD rats were randomly divided into two groups for normal feeding and high-fat feeding for 4 weeks, after which the rats with normal feeding were randomized into control group and acute pancreatitis (AP) group (n=6), and those with high-fat feeding were divided into hypertriglyceridemia group, HTGP group, and honokiol treatment group (n=6). In AP, HTGP, and honokiol groups, AP models were established by intraperitoneal injection of cerulean; in honokiol group, the rats received an intraperitoneal injection of 5 mg/kg honokiol 15 min after cerulean injection. Serum TG, IL-6, and TNF-α levels were measured 24 h after the treatments, and pathological changes in the pancreas were observed with HE staining; The levels of reactive oxygen species (ROS), malondialdehyde (MDA), and glutathione peroxidase (GSH) were measured, and SIRT3 and manganese superoxide dismutase (MnSOD2) expressions were detected using Western blotting and immunohistochemistry. Transmission electron microscopy was used to examine the ultrastructure of pancreatic acinar cells and mitochondria. Compared with the those with normal feeding, the rats with high-fat feeding had significantly elevated serum TG level (P < 0.05). The rat models of AP showed significantly increased serum levels of IL-6, TNF-α, and MDA and decreased GSH level and expressions of SIRT3 and MnSOD2, with obvious edema and inflammatory cell infiltration and enhanced ROS fluorescence intensity in the pancreas and ultrastructural damages of the acinar cells and mitochondria. In rats with HTGP, honokiol treatment significantly decreased serum levels of IL-6, TNF-α, and MDA, increased GSH level and SIRT3 and MnSOD2 expressions, reduced ROS production, and alleviated ultrastructural damage of the acinar cells and mitochondria in the pancreas. Honokiol reduce oxidative stress and alleviates pancreatic injuries in HTGP rats possibly by activating the SIRT3-MnSOD2 pathway.

Ethanol Extract of Centella asiatica Improved Methamphetamine-Induced Neurotoxicity on Mouse Model via Stimulating Superoxide Dismutase II and microRNA-34A Expression

Neurotoxicity induced by a psychostimulant drug, methamphetamine (METH) is associated with devastating and persistent neurotoxicity effects on the central nervous system (CNS). Centella asiatica (CA) is known as an antioxidant and neuroprotective agent. However, there is a limited study on natural-derived therapeutic to attenuate neurotoxicity induced by METH. We aimed to investigate the effects of METH and ethanol extract CA (CAE) on motor performance of animal model and the expression of manganese superoxide dismutase II (SOD2) and microRNA-34a (miR-34a) in the brain tissue. Male Sprague-Dawley rats were administered with METH (50 mg/kg per body weight) twice per day for 4 days, CAE (300 mg/kg &amp; 500 mg/kg per body weight for 21 days and combination of METH and CAE for 21 day(s). Weight of rat was measured and motor performance was evaluated using vertical pole and narrow beam tests. Expression of SOD2 and miR-34a were measured using Quantitative Real-time Polymerase Chain Reaction (RT-qPCR). Group III (300 mg/kg CAE); p&lt;0.001, Group IV (500 mg/kg CAE); p&lt;0.001, Group V (METH+300 mg/kg CAE); p&lt;0.01 and Group VI (METH+500 mg/kg CAE); p&lt;0.01 significantly improved latency in the vertical pole test compared to METH group. Meanwhile, Group III (300 mg/kg CAE); p&lt;0.001 and Group IV (500 mg/kg CAE); p&lt;0.001 significantly decreased latency in the narrow beam test compared to METH. Post-treatment of CAE on METH-treated rats, Group V (METH+300 mg/kg CAE) and Group VI (METH+500 mg/kg CAE) non-significantly upregulated the SOD2 expression by 3.78±1.03 and 4.05±0.19 folds compared to METH, respectively. Post-treatment of CAE on METH-treated rats, Group V (METH+300 mg/kg CAE) and Group VI (METH+500 mg/kg CAE) non-significantly upregulated the miR-34a expression by (7.02±3.73) and (6.75±1.94) folds compared to METH, respectively. CAE could be suggested as a promising natural-derived therapeutic for METH-induced neurotoxicity to ameliorating motor performance and triggering SOD2 and miR-34a expression.

Loganic acid regulates the transition between epithelial and mesenchymal-like phenotypes by alleviating MnSOD expression in hepatocellular carcinoma cells

AimsCancer metastasis is the major cause of cancer-related deaths. There are few prior studies reported on molecules targeting C-X-C chemokine receptor (CXCR) family and manganese superoxide dismutase (MnSOD). CXCRs are known to involve in angiogenesis, metastasis, cell survival and MnSOD is reported to be related in Epithelial–mesenchymal transition (EMT). Main methodsCell viability and cell proliferation were measured by MTT and BrdU assay. Protein expression level of CXCR4/7, MMP-2/9, MnSOD, and EMT markers were evaluated by Western blot analysis. mRNA levels of Snail and Occludin were analyzed by Real-time RT-qPCR. Expression of EMT markers in cells was observed by immunocytochemistry. Cell invasion and migrations were evaluated by wound healing assay and boyden chamber assay. Key findingsWe noticed that LGA abolished proliferation, invasive ability, and cellular migration. LGA down-regulated the protein levels of mesenchymal markers such as Twist, Snail, Fibronectin, and Vimentin in CXCL12-treated HCC cells. It also suppressed the gelatinolytic activity of MMP-9/2. The amplification of MnSOD increased EMT-like phenotypes but with LGA treatment, these phenotypes were markedly attenuated. The overexpression of MnSOD increased the ROS levels significantly but ROS levels were decreased upon exposure to LGA and deletion of MnSOD suppressed the levels of various mesenchymal proteins. SignificanceLGA could function as a novel anti-metastatic agent by suppressing metastasis and EMT process via attenuation of MnSOD expression in hepatocellular carcinoma cells.

Potential function of loliolide as a novel blocker of epithelial-mesenchymal transition in colorectal and breast cancer cells

Loliolide (LL), a naturally occurring monoterpenoid lactone isolated from Vicia tenuifolia Roth, can exhibit numerous pharmacological effects such as those related to anti-Parkinson, anti-oxidant, anti-cholinesterase, and anti-depressant. Epithelial-mesenchymal transition (EMT) plays a pivotal role in regulating tumor metastasis. CXCR4 and CXCR7 are G-protein-coupled receptors (GPRs), which can be stimulated by CXCL12. CXCL12/CXCR4/CXCXR7 axis can cause activation of multiple pathways including MAPKs, JAK/STAT pathway, and manganese superoxide dismutase (MnSOD) signaling. These events can initiate EMT process and induce cell invasion and migration. Here, we investigated whether LL can modulate the CXCR4 and CXCR7 and EMT process in colon cancer and breast cancer cells. We found that LL suppressed levels of CXCR4 and CXCR7, and exerted an inhibitory effect on these chemokines even after stimulation by CXCL12. LL suppressed expression of MnSOD and mesenchymal markers, whereas induced epithelial markers. In addition, LL significantly attenuated cellular invasion, migration, and metastasis. We noted that LL inhibited CXCR4/7 and EMT process even after stimulation of CXCL12 and MnSOD overexpression. Therefore, in this study, we provide evidences that targeting CXCR4/7 and MnSOD could inhibit the invasion, migration, and metastasis of cancer cells as well as negatively regulate the EMT process. Overall, our study suggested that LL might act as a potent suppressor of EMT process against colon and breast cancer cells.

Manganese alleviates heat stress of primary cultured chick embryonic myocardial cells via enhancing manganese superoxide dismutase expression and attenuating heat shock response

Manganese (Mn) is an essential trace element that has been shown to attenuate the adverse effects of heat stress in the heart of broiler breeders and embryos. However, the underlying molecular mechanisms involving this process remain unclear. Therefore, two experiments were conducted to investigate the possible protective mechanisms of Mn on primary cultured chick embryonic myocardial cells exposed to heat challenge. In experiment 1, the myocardial cells were exposed to 40 °C (normal temperature, NT) and 44 °C (high temperature, HT) for 1, 2, 4, 6 or 8 h. In experiment 2, the myocardial cells were preincubated with no Mn supplementation (CON), 1 mmol/L of Mn as the inorganic MnCl2 (iMn) or organic Mn proteinate (oMn) under NT for 48 h, and then continuously incubated under NT or HT for another 2 or 4 h. The results from experiment 1 showed that the myocardial cells incubated for 2 or 4 h had the highest (P < 0.0001) heat-shock protein 70 (HSP70) or HSP90 mRNA levels than those incubated for other incubation times under HT. In experiment 2, HT increased (P < 0.05) the heat-shock factor 1 (HSF1) and HSF2 mRNA levels as well as Mn superoxide dismutase (MnSOD) activity of myocardial cells compared with NT. Furthermore, supplemental iMn and oMn increased (P < 0.02) HSF2 mRNA level and MnSOD activity of myocardial cells compared with the CON. Under HT, the HSP70 and HSP90 mRNA levels were lower (P < 0.03) in iMn group than in the CON group, in oMn group than in iMn group; and the MnSOD mRNA and protein levels were higher (P < 0.05) in oMn group than in the CON and iMn groups. These results from the present study indicate that supplemental Mn, especially oMn, could enhance the MnSOD expression and attenuate heat shock response to protect against heat challenge in primary cultured chick embryonic myocardial cells.

Expression Changes of SIRT1 and FOXO3a Significantly Correlate with Oxidative Stress Resistance Genes in AML Patients.

The increased metabolism in acute myeloid leukemia (AML) malignant cells resulted in the production of high levels of free radicals, called oxidative stress conditions. To avoid this situation, malignant cells produce a considerable amount of antioxidant agents, which will lead to the release of a continuous low level of reactive oxygen species (ROS), causing genomic damage and subsequent clonal evolution. SIRT1 has a key role in driving the adaptation to this condition, mainly through the deacetylation of FOXO3a that affects the expression of oxidative stress resistance target genes such as Catalase and Manganese superoxide dismutase (MnSOD). The aim of this study is to simultaneously investigate the expression of SIRT1, FOXO3a, and free radical-neutralizing enzymes such as Catalase and MnSOD in AML patients and measure their simultaneous change in relation to each other. The gene expression was analyzed using Real Time-PCR in 65 AML patients and 10 healthy controls. Our finding revealed that expression of SIRT1, FOXO3a, MnSOD and Catalase was significantly higher in AML patients in comparison to healthy controls. Also, there was a significant correlation between the expression of SIRT1 and FOXO3a, as well as among the expression of FOXO3a, MnSOD and Catalase genes in patients. According to the results, the expression of genes involved in oxidative stress resistance was higher in AML patients, which possibly contributed to the development of malignant clones. Also, the correlation between the expression of SIRT1 and FOXO3a gene reflects the importance of these two genes in increased oxidative stress resistance of cancer cells.

Aspartame consumption during pregnancy impairs placenta growth in mice through sweet taste receptor-reactive oxygen species-dependent pathway

The prevalence of obesity has risen dramatically over recent years, and so has the prevalence of adverse obesity-associated pregnancy outcomes. To combat obesity, the calorie contents of many foods and beverages may be reduced by the use of artificial sweeteners, such as aspartame. However, animal studies suggest that aspartame and its metabolites may exhibit toxicity, and the effects of aspartame on pregnancy are largely unknown. In this study, we treated pregnant mice with aspartame by oral gavage and found that the treatment decreased fasting blood glucose level, whereas systolic blood pressure was elevated. Importantly, the aspartame-treated animals also had low placenta and fetus weights, as well as reduced thickness of the placenta decidua layer. Moreover, aspartame decreased the expression of epithelial-mesenchymal transition proteins and manganese superoxide dismutase (MnSOD) in mouse placentae. In order to clarify the mechanisms though which aspartame affects placenta, we performed experiments on 3A-sub-E trophoblasts. In the cells, aspartame treatments induced cell cycle arrest and reduced the proliferation rate, epithelial-mesenchymal transition, migration activity and invasion activity. We also found that aspartame increased reactive oxygen species (ROS) levels to hyper-activate Akt and downregulate MnSOD expression. Pretreatment with antioxidants or sweet taste receptor inhibitors reversed the effects of aspartame on trophoblast function. We also found that the aspartame metabolite phenylalanine similarly induced ROS production and affected proliferation of trophoblasts. Taken together, our data suggest that aspartame consumption during pregnancy may impact the structure, growth and function of the placenta via sweet taste receptor-mediated stimulation of oxidative stress.

Electroacupuncture preconditioning alleviates renal injury and oxidative stress through Sirt3/MnSOD pathway in type 2 diabetic rats

To explore the protective effect and molecular mechanism of electroacupuncture (EA) preconditioning on renal injury in type 2 diabetic rats. Fifty male Wistar rats were randomly divided into control, model, EA, EA+inhibitor, and inhibitor groups, with 10 rats in each group. Diabetes model was established by high fat and high glucose diet and intraperitoneal injection of streptozotocin (40 mg/kg). EA (2 Hz, 1 mA) preconditioning was applied to "Guanyuan" (CV4), "Zhongwan" (CV12), bilateral "Zusanli" (ST36) and "Fenglong" (ST40) for 15 min, once every other day for 8 weeks. Rats of the inhibitor and EA+inhibitor groups were given intraperitoneal injection of 3-TYP (50 mg/kg) once every other day for a total of 3 times. The body weight, kidney mass, and renal index were recorded. The contents of urine microalbumin (ALB), 24 h urine 8-hydroxydeoxyguanosine (8-OHdG) and activities of reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), glutathione glycine peroxidase (GSH-Px) in kidney were detected by ELISA. The activities of mitochondrial respiratory chain enzyme complex (RCCⅠ-RCCⅣ) in kidney were detected using spectrophotometric method. HE staining, Masson staining and transmission electron microscopy were used to observe the changes of renal structure. The protein and mRNA expressions of silent information regulator 3 (Sirt3), manganese superoxide dismutase (MnSOD) in kidney were detected by Western blot and quantitative real-time PCR, respectively. After modeling and compared with the control group, the contents of ALB, the renal index, activity of ROS and content of 8-OHdG, and the renal collagen volume fraction (CVF) were increased (P<0.01), while the activities of SOD, CAT and GSH-Px, RCCⅠ-RCCⅣ, and the mRNA and protein expressions of Sirt3 and MnSOD were decreased (P<0.01). After the treatment and compared with the model group, the contents of ALB, the renal index, ROS, 8-OHdG, and the CVF were decreased in the EA group(P<0.01, P<0.05), while the activities of SOD, CAT, GSH-Px, RCCⅠ-RCCⅣ, and Sirt3 and MnSOD expression levels were increased (P<0.01, P<0.05)；the RCCⅡ activity and the expression level of MnSOD mRNA were increased (P<0.05) in the EA+inhibitor group; the ALB and 8-OHdG contents and the CVF in the inhibitor group were increased (P<0.05), while the activity of SOD, and Sirt3 and MnSOD expression levels were decreased (P<0.05). In comparison with the EA group, the contents of ALB, the renal index, activities of ROS and 8-OHdG contents, and the CVF were increased (P<0.05, P<0.01), activities of SOD, CAT and GSH-Px and RCCⅠ and RCCⅡ, and the mRNA and protein expressions of Sirt3 and MnSOD were decreased (P<0.05, P<0.01) in both EA+inhibitor group and inhibitor group, whereas the activities of RCCⅢ and RCCⅣ were decreased in the inhibitor group (P<0.05). The therapeutic effect of inhibitor was notably inferior to that of EA+inhibitor in decreasing ALB and 8-OHdG contents, and CVF (P<0.01), and in up-regulating SOD and RCCⅡ activities, Sirt3 and MnSOD expression levels (P<0.01, P<0.05). EA preconditioning can increase the expressions of renal Sirt3 and MnSOD in type 2 diabetic rats, thereby reducing the oxidative stress response and protecting the kidneys.

An accidental discovery of mannan-oligosaccharide's protection effect against air exposure and its potential mechanism in hybrid grouper (Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀).

The original objective was to explore the potential benefiting effects of three prebiotics in hybrid grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀). Therefore, three experimental diets (basal diet + 1% fructooligosaccharide, Diet F; basal diet + 1% inulin, Diet I; basal diet + 0.3% mannan-oligosaccharide, Diet M) and one basal diet (Diet C) were prepared and a feeding trial was conducted. However, at the end of the fourth week into the feeding experiment, a water-leaking accident occurred and fishes of all groups went through an unexpected air exposure event. Surprisingly, different prebiotic-supplemented groups showed significantly different air exposure tolerance: the mortality of M group was significantly lower (P ≤ 0.05) than all the other groups. Examination of antioxidant, non-specific immunity, and stress parameters revealed that comparing to control group, M group showed significantly increased catalase (CAT), acid phosphatase (ACP), and alkaline phosphatase (AKP) activities, decreased superoxide dismutase (SOD) activity, and similar cortisol level (P ≤ 0.05). Real-time PCR experiment revealed that M group significantly increased the expression of CAT, glutathione peroxidase (GPx), and manganese superoxide dismutase (MnSOD) genes in head kidney (P ≤ 0.05). Overall, M exhibited the best anti-air exposure/antioxidative stress effects among the three prebiotics and could be considered a promising feed additive to relieve air exposure/oxidative stress in hybrid grouper culture.

Transplantation of Astrocytic Mitochondria Modulates Neuronal Antioxidant Defense and Neuroplasticity and Promotes Functional Recovery after Intracerebral Hemorrhage.

Astrocytes release functional mitochondria (Mt) that play regulatory and prosurvival functions on entering adjacent cells. We recently demonstrated that these released Mts could enter microglia to promote their reparative/prophagocytic phenotype that assists in hematoma cleanup and neurological recovery after intracerebral hemorrhage (ICH). However, the relevance of astrocytic Mt transfer into neurons in protecting brain after ICH is unclear. Here, we found that ICH causes a robust increase in superoxide generation and elevated oxidative damage that coincides with loss of the mitochondrial enzyme manganese superoxide dismutase (Mn-SOD). The damaging effect of ICH was reversed by intravenous transplantation of astrocytic Mt, which on entering the brain (and neurons), restored Mn-SOD levels and reduced neurological deficits in male mice subjected to ICH. Using an in vitro ICH-like injury model in cultured neurons, we established that astrocytic Mt on entering neurons prevented reactive oxygen species-induced oxidative stress and neuronal death by restoring neuronal Mn-SOD levels while at the same time promoted neurite extension and upregulation of synaptogenesis-related gene expression. Furthermore, we found that Mt genome-encoded small peptide humanin, which is normally abundant in Mt, could simulate Mt-transfer effect on neuronal Mn-SOD expression, oxidative stress, and neuroplasticity under ICH-like injury. This study demonstrates that adoptive astrocytic Mt transfer enhances neuronal Mn-SOD-mediated antioxidative defense and neuroplasticity in the brain, which potentiate functional recovery following ICH.SIGNIFICANCE STATEMENT Mitochondrial dysfunction and antioxidant defense play essential roles in brain damage after ICH. Astrocytes release functional Mt that enters adjacent cells to help brain homeostatic function. Here, we show that systemic transplantation of astrocytic Mt restores ICH-impaired neuronal antioxidative defense, enhances neurite outgrowth, and improves stroke recovery after ICH. Our study suggests that systemic transplantation of astrocytic Mt could be considered as a novel and potentially promising strategy for ICH treatment.

Preconditioning exercise reduces hippocampal neuronal damage via increasing Klotho expression in ischemic rats

Considerable amounts of oxidants are produced in cerebral ischemia, where oxidative stress plays a key role in neuronal damage after ischemia. Klotho, an anti-aging protein, alleviates oxidative stress by activating the transcription of an important antioxidant enzyme, manganese superoxide dismutase (MnSOD), in the nervous system. Thus, increased Klotho expression level could lead to a reduction in neuronal damages after brain ischemia via lowering oxidative stress. It is known that physical activity increases Klotho expressions. In this study, we assessed neuroprotective effects of preconditioning exercise in rats (treadmill running at a speed of 20 m/min,30 min/day, six days/week, for3 weeks) on hippocampal Klotho and MnSOD expression in the brain using an animal model of stroke, middle cerebral artery occlusion (MCAO). Our study revealed a reduction in hippocampal Klotho and MnSOD expression as well as CA1 neuronal activity in MCAO compared to the sham group. Exercise prevented the ischemia-induced decline in Klotho and MnSOD expression levels as well as CA1 neuronal activity in Exercise + MCAO compared to the MCAO group. Also, exercise significantly improved the neurological scores and reduced brain infarction area in Exercise + MCAO in comparison to MCAO group. There was a post-ischemia deficit in the working memory, as measured by spontaneous alternation percentage using Y-maze test, in MCAO compared to the sham group. The latter effect was not observed in the Exercise + MCAO group, which could be related to an increase in the antioxidant capacity as exhibited by Klotho and MnSOD up-regulation. The results were confirmed with a positive correlation between Klotho expression and MnSOD expression which allows proposing Klotho as a potential neuroprotective protein in ischemic stroke with respect to antioxidant defense. In general, the present study suggested that preconditioning exercise induced upregulation of Klotho and MnSOD, as well as attenuated the post-ischemic injuries. The upregulation of Klotho might be an underlying mechanism by which preconditioning exercise plays as a neuroprotective factor against post-ischemic neural injuries in ischemic rats.

2,3,5,6-Tetramethylpyrazine Targets Epithelial-Mesenchymal Transition by Abrogating Manganese Superoxide Dismutase Expression and TGFβ-Driven Signaling Cascades in Colon Cancer Cells.

Epithelial-mesenchymal transition (EMT) is a crucial process in which the polarized epithelial cells acquire the properties of mesenchymal cells and gain invasive properties. We have previously demonstrated that manganese superoxide dismutase (MnSOD) can regulate the EMT phenotype by modulating the intracellular reactive oxygen species. In this report, we have demonstrated the EMT-suppressive effects of 2,3,5,6-Tetramethylpyrazine (TMP, an alkaloid isolated from Chuanxiong) in colon cancer cells. TMP suppressed the expression of MnSOD, fibronectin, vimentin, MMP-9, and N-cadherin with a parallel elevation of occludin and E-cadherin in unstimulated and TGFβ-stimulated cells. Functionally, TMP treatment reduced the proliferation, migration, and invasion of colon cancer cells. TMP treatment also modulated constitutive activated as well as TGFβ-stimulated PI3K/Akt/mTOR, Wnt/GSK3/β-catenin, and MAPK signaling pathways. TMP also inhibited the EMT program in the colon cancer cells-transfected with pcDNA3-MnSOD through modulation of MnSOD, EMT-related proteins, and oncogenic pathways. Overall, these data indicated that TMP may inhibit the EMT program through MnSOD-mediated abrogation of multiple signaling events in colon cancer cells.

The RelB-BLNK Axis Determines Cellular Response to a Novel Redox-Active Agent Betamethasone during Radiation Therapy in Prostate Cancer.

Aberrant levels of reactive oxygen species (ROS) are potential mechanisms that contribute to both cancer therapy efficacy and the side effects of cancer treatment. Upregulation of the non-canonical redox-sensitive NF-kB family member, RelB, confers radioresistance in prostate cancer (PCa). We screened FDA-approved compounds and identified betamethasone (BET) as a drug that increases hydrogen peroxide levels in vitro and protects non-PCa tissues/cells while also enhancing radiation killing of PCa tissues/cells, both in vitro and in vivo. Significantly, BET increases ROS levels and exerts different effects on RelB expression in normal cells and PCa cells. BET induces protein expression of RelB and RelB target genes, including the primary antioxidant enzyme, manganese superoxide dismutase (MnSOD), in normal cells, while it suppresses protein expression of RelB and MnSOD in LNCaP cells and PC3 cells. RNA sequencing analysis identifies B-cell linker protein (BLNK) as a novel RelB complementary partner that BET differentially regulates in normal cells and PCa cells. RelB and BLNK are upregulated and correlate with the aggressiveness of PCa in human samples. The RelB-BLNK axis translocates to the nuclear compartment to activate MnSOD protein expression. BET promotes the RelB-BLNK axis in normal cells but suppresses the RelB-BLNK axis in PCa cells. Targeted disruptions of RelB-BLNK expressions mitigate the radioprotective effect of BET on normal cells and the radiosensitizing effect of BET on PCa cells. Our study identified a novel RelB complementary partner and reveals a complex redox-mediated mechanism showing that the RelB-BLNK axis, at least in part, triggers differential responses to the redox-active agent BET by stimulating adaptive responses in normal cells but pushing PCa cells into oxidative stress overload.

Chemobrain: mitoxantrone-induced oxidative stress, apoptotic and autophagic neuronal death in adult CD-1 mice.

Mitoxantrone (MTX) is a topoisomerase II inhibitor used to treat a wide range of tumors and multiple sclerosis but associated with potential neurotoxic effects mediated by hitherto poorly understood mechanisms. In adult male CD-1 mice, the underlying neurotoxic pathways of a clinically relevant cumulative dose of 6mg/kg MTX was evaluated after biweekly administration for 3weeks and sacrifice 1week after the last administration was undertaken. Oxidative stress, neuronal damage, apoptosis, and autophagy were analyzed in whole brain, while coronal brain sections were used for a closer look in the hippocampal formation (HF) and the prefrontal cortex (PFC), as these areas have been signaled out as the most affected in 'chemobrain'. In the whole brain, MTX-induced redox imbalance shown as increased endothelial nitric oxide synthase and reduced manganese superoxide dismutase expression, as well as a tendency to a decrease in glutathione levels. MTX also caused diminished ATP synthase β expression, increased autophagic protein LC3 II and tended to decrease p62 expression. Postsynaptic density protein 95 expression decreased in the whole brain, while hyperphosphorylation of Tau was seen in PFC. A reduction in volume was observed in the dentate gyrus (DG) and CA1 region of the HF, while GFAP-ir astrocytes increased in all regions of the HF except in the DG. Apoptotic marker Bax increased in the PFC and in the CA3 region, whereas p53 decreased in all brain areas evaluated. MTX causes damage in the brain of adult CD-1 mice in a clinically relevant cumulative dose in areas involved in memory and cognition.

Daidzin targets epithelial-to-mesenchymal transition process by attenuating manganese superoxide dismutase expression and PI3K/Akt/mTOR activation in tumor cells

AimsEpithelial–mesenchymal transition (EMT) is a process during which epithelial cells lose their polarity and gain invasive properties to transform into mesenchymal cells. A few recent studies have reported that manganese superoxide dismutase (MnSOD) can effectively modulate EMT phenotype by influencing cellular redox environment via altering the intracellular ratio between O2− and H2O2. Daidzin (DDZ), a naturally occurring isoflavone isolated from Pueraria lobate (Fabaceae), has numerous pharmacologic effects including anti-cholesterol, anti-angiocardiopathy, anti-cancer. However, the potential inhibitory impact of DDZ on cancer metastasis and specifically on the EMT process has not been evaluated. We aimed to evaluate the possible relationship between MnSOD and EMT as well as influence of DDZ on these two processes in colon and prostate carcinoma cells. Main methodsCell viability was measured by MTT and real time cell analysis (RTCA) assay. Protein expression level of EMT markers and Akt/mTOR/PI3K signaling pathway were evaluated by Western blot analysis. Expression of EMT markers in cells was observed by immunocytochemistry. Cell invasion and migrations were evaluated by wound healing assay and Boyden chamber assay. Key findingsDDZ can block EMT accompanied with down-regulation of MnSOD, fibronectin, vimentin, MMP-9, MMP-2, N-cadherin, twist, and Snail, and up-regulation of occludin and E-cadherin in both unstimulated and TGFβ-induced cells. In addition, DDZ exposure also attenuated cell proliferation, invasion, and metastasis by reversing the EMT process in SNU-C2A, DU145, and PC-3 cells. DDZ treatment also modulated activation of PI3K/Akt/mTOR signaling cascades in DU145 cells. Moreover, an overexpression of MnSOD or silencing of MnSOD expression modulated EMT-related proteins, PI3K/Akt/mTOR activation and invasive activity. SignificanceThis is first finding on the DDZ in regulating MnSOD and EMT process by targeting PI3K/Akt/mTOR pathway in both colorectal and prostate cancer cell lines. Our data indicated that DDZ might act as a potent suppressor of EMT by affecting MnSOD expression in tumor cells.

Mitochondria play a key role in oxidative stress-induced pancreatic islet dysfunction after severe burns.

Severe burns are often complicated with hyperglycemia in part caused by pancreatic islet dysfunction. Previous studies have revealed that in diabetes mellitus, the pancreatic islet dysfunction is partly attributed to oxidative stress. However, the role and mechanism of oxidative stress in hyperglycemia after severe burns remain unclear. Therefore, the purpose of this study was to explore the level and mechanism of oxidative stress in pancreatic islets after severe burns and the antioxidant effect of sodium pyruvate. A 30% total body surface area full-thickness burn model was established using male C57BL/6 mice. Fasting blood glucose and glucose-stimulated insulin secretion (GSIS) 24 hours post severe burns were detected. The levels of reactive oxygen species (ROS) and mitochondrial ROS of islets were detected. The activities of complexes in the mitochondrial respiratory chain of islets were measured. The main antioxidant defense system, glutaredoxin system, and thioredoxin system-related indexes were detected, and the expression of manganese superoxide dismutase (Mn-SOD) was measured. In addition, the antioxidant activity of sodium pyruvate was evaluated post severe burns. After severe burns, fasting blood glucose levels increased, while GSIS levels decreased, with significantly elevated ROS levels of pancreatic islets. The activity of complex III decreased and the level of mitochondrial ROS increased significantly post severe burns. For the detoxification of ROS, the expressions of thioredoxin 2, thioredoxin reductase 2, and Mn-SOD located in mitochondria decreased. Sodium pyruvate reduced the level of mitochondrial ROS in islet cells and improved the GSIS of islets after severe burns. The high level of mitochondrial ROS of islets is caused by reducing the activity of complex III in mitochondrial respiratory chain, inhibiting mitochondrial thioredoxin system, and downregulating Mn-SOD post severe burns. Sodium pyruvate plays an antioxidant role post severe burns in mice islets and improves the islet function.

A role for Snail-MnSOD axis in regulating epithelial-to-mesenchymal transition markers expression in RPE cells

Age-related macular degeneration (AMD) is a common cause of vision loss. The epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells, accompanied by oxidative damage, plays a crucial role in AMD. It is well known that manganese superoxide dismutase (MnSOD) encoded by SOD2 is a critical molecule in fighting against oxidative stress, and Snail encoded by SNAI1 is the essential transcription factor for EMT. However, the effect of MnSOD on EMT and the underlying mechanism in RPE cells remains unknown. In this study, we found that MnSOD knockdown triggered the EMT by upregulating Snail, while MnSOD overexpression reversed EMT even with TGFβ treatment in RPE cells, and the anti-oxidative stress activity of MnSOD mediated this observation. In addition, Snail depletion increased both expression and activity of MnSOD while Snail overexpression decreased MnSOD expression and activity, and Dual-luciferase reporter and ChIP assays showed that Snail directly bound to E-box (CACCTG) in the SOD2 promoter. Moreover, MnSOD over-expression and Snail interference co-treatment strengthened the anti-oxidation and EMT reversing. Therefore, our findings demonstrate that MnSOD prevents EMT of RPE cells in AMD through inhibiting oxidative injury to RPE. Moreover, a critical EMT transcription factor, Snail, functions as a new negative transcriptional factor of SOD2. Herein, the Snail-MnSOD axis forms a mutual loop in the development of AMD, which may be a novel systemic treatment target for preventing AMD.