Inhibited Hydrogen Peroxide-induced Apoptosis Research Articles

PS-B12-9: ASTRAGALOSIDE IV INHIBITS HYDROGEN PEROXIDE-INDUCED APOPTOSIS IN H9C2 CELLS BY ATTENUATING OXIDATIVE STRESS AND MITOCHONDRIAL DAMAGE

Backgrounds: Oxidative stress and mitochondrial damage play an important role in the pathology of cardiomyocytes apoptosis. However, the effects of Astragaloside IV(As-IV) on mitochondrial function have not been uncertain. Therefore, we assumed that As-IV inhibits hydrogen peroxide-induced apoptosis in H9c2 cells by attenuating oxidative stress and mitochondrial damage. Objectives: To investigate the effects and mechanisms of As-IV on hydrogen peroxide-induced apoptosis in H9c2 cells. Methods: H9c2 cells were divided into three groups, including normal control group (cultured without intervention), hydrogen peroxidegroup (cultured with 200 μmol/L hydrogen peroxide for 2 hours), As-IV group (cultured with 100 μmol/L As-IV for 1 hour), As-IV with hydrogen peroxide group (pretreated with 100 μmol/L As-IV for 1 hour, then incubated with hydrogen peroxide for 2 hours). FITC/PI and DCFH-DA are stained to examine levels of apoptosis and ROS receptively. Levels of SOD and MDA were measured. Stained with JC-1 probe to observe the change of mitochondrial membrane potential (MMP). Western-blot was detected to analyze the expression of Drp-1. Results 1: The apoptosis rate of hydrogen peroxide group ((13.22 ± 3.17 vs 40.55 ± 13.74)%, P < 0.05) was significantly higher than that of control group, which was lower in As-IV with hydrogen peroxide group((23.43 ± 4.3 vs 40.55 ± 13.74) %, P < 0.05). 2. The ROS levels were higher in hydrogen peroxide group than control group((73.53 ± 5.33 vs 39.02 ± 7.90) %, P < 0.05), which were significant reduced in As-IV with hydrogen peroxide group((57.6 ± 4.63 vs 73.53 ± 5.33) %, P < 0.05) Meanwhile, the activity of MDA was increased and the activity of SOD was decreased in hydrogen peroxide group compared with that in control group((10.97 ± 0.56 vs 4.85 ± 0.55) nmol/mL, P < 0.05), ((1192.23 ± 341.59 vs 2710.95 ± 274.32)U/L, P < 0.05). Compared with hydrogen peroxide group, As-IV with hydrogen peroxide group significantly decrease the activity of MDA and increase the activity of SOD ((6.58 ± 0.79 vs 10.97 ± 0.56) nmol/mL, P < 0.05), ((1984.66 ± 188.81 vs 1192.23 ± 341.59) U/L, P < 0.05). 3. MMP was lower and the expression of Drp1 was higher in hydrogen peroxide group than that in control group ((0.31 ± 0.01 vs 1.52 ± 0.25) %, P < 0.05), ((0.86 ± 0.003 vs 0.45 ± 0.004) %, P < 0.05). Compared with hydrogen peroxide group, MMP was significantly increased and the expression of Drp1 was downregulated ((0.65 ± 0.38 vs 0.31 ± 0.01) %, P < 0.05), ((0.72 ± 0.005 vs 0.86 ± 0.003) %, P < 0.05). Conclusions: As-IV exerts protective effects on hydrogen peroxide-induced apoptosis by attenuating oxidative stress and mitochondrial damage.

Exercise-induced circulating exosomes potentially prevent pelvic organ prolapse in clinical practice via inhibition of smooth muscle apoptosis

BackgroundThis study aimed to explore the potential mechanisms of exercise to prevent pelvic organ prolapse (POP) and search for diagnostic indictors for POP. MethodsWe used two clinical POP datasets with patients’ information (GSE12852 and GSE53868), a dataset consisting of altered microRNA expression in circulating blood after exercise (GSE69717) for bioinformatic analysis and clinical diagnostic analysis, while a series of cellular experiments were conducted for preliminary mechanical validation. ResultsOur results show that AXUD1 is highly expressed in the smooth muscle of the ovary and is a key pathogenic gene in POP, while miR-133b is a key molecule in the regulation of POP by exercise-induced serum exosomes. The AUCs of AXUD1 for POP diagnosis were 0.842 and 0.840 in GSE12852 and GSE53868 respectively. At cut-off value = 9.627, the sensitivity and specificity of AXUD1 for predicating POP is 1.000 and 0.833 respectively for GSE53868, while at cut-off value = 3324.640, the sensitivity and specificity of AXUD1 for predicating POP is 0.941 and 0.812 separately for GSE12852. Analysis and experiments confirmed that miR-133b can directly regulate AXUD1. miR-133b mediated C2C12 myoblasts proliferation and inhibited hydrogen peroxide-induced apoptosis. ConclusionsOur study proved that AXUD1 is a good clinical diagnostic indicator for POP and provided a theoretical basis for future prevention of POP through exercise and a potential target for intervention in muscle dysfunction.

Rhein inhibits hydrogen peroxide-induced apoptosis of human umbilical vein endothelial cells and its mechanism

This study investigated the effect of rhein(RH) on the apoptosis and autophagy of human umbilical vein endothelial cells(HUVECs) induced by hydrogen peroxide(H_2O_2) and its underlying mechanism. The oxidative damage model in HUVECs was established and the cells were divided into different treatment groups. Cell survival rate was detected by MTT assay, apoptosis by Annexin V-FITC/PI double staining and Hoechst 33258 fluorescence staining, autophagy by Ad-mCherry-GFP-LC3 B adenovirus transfection, and protein expression by Western blot. The results showed that RH could protect cells by increasing the cell survival rate in a dose-dependent manner, decreasing the expression of apoptosis-related proteins(Bax and cleaved caspase-3) and the ratio of Bax/Bcl-2, elevating the expression of Bcl-2, up-regulating the expression of microtubule-associated protein 1 light chain 3(LC3)-Ⅱ, and down-regulating the expression of p62. Adenovirus transfection results showed that RH could increase the green and red spots, as well as the yellow spots. However, after the addition of autophagy inhibitor 3-MA, autophagy was reduced and apoptosis was increased. RH could enhance the expression of silent information regulator 2 related enzyme 1(SIRT1). The addition of SIRT1 inhibitor EX-527 reduced the protective effect of RH and cell viability. The addition of 3-MA had no effect on the expression of SIRT1 protein, but the expression of SIRT1 and LC3-Ⅱ proteins decreased and the expression of p62 increased after the addition of EX-527. After RH treatment, the phosphorylation of adenosine monophosphate-activated protein kinase(AMPK) increased, while that of the mechanistic target of rapamycin(mTOR) decreased in a dose-dependent manner. Moreover, this effect could be weakened by the AMPK inhibitor compound C. RH may enhance autophagy through SIRT1/AMPK/mTOR pathway to reduce H_2O_2-induced apoptosis of HUVECs.

MicroRNA-1205, encoded on chromosome 8q24, targets EGLN3 to induce cell growth and contributes to risk of castration-resistant prostate cancer.

The chromosome 8q24.21 locus, which contains the proto-oncogene c-MYC, long non-coding RNA PVT1, and microRNAs (miRs), is the most commonly amplified region in human prostate cancer. A long-range interaction of genetic variants with c-MYC or long non-coding PVT1 at this locus contributes to the genetic risk of prostate cancer. At this locus is a cluster of genes for six miRs (miR-1204, −1205, −1206, −1207–3p, −1207–5p, and −1208), but their functional role remains elusive. Here, the copy numbers and expressions of miRs-1204~1208 were investigated using quantitative PCR for prostate cancer cell lines and primary tumors. The data revealed that copy numbers and expression of miR-1205 were increased in both castration-resistant prostate cancer cell lines and in primary tumors. In castration-resistant prostate cancer specimens, the copy number at the miR-1205 locus correlated with expression of miR-1205. Furthermore, functional analysis with an miR-1205 mimic, an miR-1205 inhibitor, and CRISPR/Cas9 knockout revealed that, in human prostate cancer cells, miR-1205 promoted cell proliferation and cell cycle progression and inhibited hydrogen peroxide-induced apoptosis. In these cells, miR-1205 downregulated expression of the Egl-9 family hypoxia inducible factor 3 (EGLN3) gene and targeted a site in its 3’-untranslated region to downregulate its transcriptional activity. Thus, by targeting EGLN3, miR-1205 has an oncogenic role and may contribute to the genetic risk of castration-resistant prostate cancer.

Suppression of Calpain-2 by Small Interfering RNA Inhibits Hydrogen Peroxide-Induced Apoptosis in Rat Pancreatic Acinar Cells AR42J

Suppression of Calpain-2 by Small Interfering RNA Inhibits Hydrogen Peroxide-Induced Apoptosis in Rat Pancreatic Acinar Cells AR42J

Kaiso protects human umbilical vein endothelial cells against apoptosis by differentially regulating the expression of B-cell CLL/lymphoma 2 family members

Endothelial cell injury can promote the development of various cardiovascular diseases, thus, fully understanding the mechanisms underlying the maintenance of vascular endothelial cell homoeostasis may help prevent and treat cardiovascular disease. Kaiso, a zinc finger and BTB domain containing transcription factor, is key to embryonic development and cancer, but how Kaiso interacts with vascular endothelium is not fully understood. We report that Kaiso has an anti-apoptotic function in human umbilical vein endothelial cells (HUVECs) and human microvascular endothelial cells (HMEC-1s). Overexpression of Kaiso significantly increased cell viability and inhibited hydrogen peroxide-induced apoptosis. Furthermore, Kaiso increased expression of B-cell CLL/lymphoma 2 (BCL2) and reduced expression of BCL2-associated X protein (BAX) and BCL2-interacting killer (BIK) by differentially regulating gene promoter activity. Methylated DNA and specific Kaiso binding site (KBS) contributed to gene regulatory activity of Kaiso. In addition, p120ctn functioned cooperatively in Kaiso-mediated transcriptional regulation.

Emerin suppresses Notch signaling by restricting the Notch intracellular domain to the nuclear membrane

Emerin is an inner nuclear membrane protein that is involved in maintaining the mechanical integrity of the nuclear membrane. Increasing evidence supports the involvement of emerin in the regulation of gene expression; however, its precise function remains to be elucidated. Here, we show that emerin downregulated genes downstream of Notch signaling, which are activated exclusively by the Notch intracellular domain (NICD). Deletion mutant experiments revealed that the transmembrane domain of emerin is important for the inhibition of Notch signaling. Emerin interacted directly and colocalized with the NICD at the nuclear membrane. Emerin knockdown induced the phosphorylation of ERK and AKT, increased endogenous Notch signaling, and inhibited hydrogen peroxide-induced apoptosis in HeLa cells. Notably, the downregulation of barrier-to-autointegration factor (BAF) or lamin A/C increased Notch signaling by inducing the release of emerin into the cytosol, implying that nuclear membrane-bound emerin acts as an endogenous inhibitor of Notch signaling. Taken together, our results indicate that emerin negatively regulates Notch signaling by promoting the retention of the NICD at the nuclear membrane. This mechanism could constitute a new therapeutic target for the treatment of emerin-related diseases.

Isoquercitrin Inhibits Hydrogen Peroxide-Induced Apoptosis of EA.hy926 Cells via the PI3K/Akt/GSK3β Signaling Pathway.

Oxidative stress plays a critical role in endothelial injury and the pathogenesis of diverse cardiovascular diseases, including atherosclerosis. Isoquercitrin (quercetin-3-glucoside), a flavonoid distributed widely in plants, exhibits many biological activities, including anti-allergic, anti-viral, anti-inflammatory, and anti-oxidative effects. In the present study, the inhibitory effect of isoquercitrin on H2O2-induced apoptosis of EA.hy926 cells was evaluated. MTT assays showed that isoquercitrin significantly inhibited H2O2-induced loss of viability in EA.hy926 cells. Hoechst33342/PI and Annexin V-FITC/PI fluorescent double staining indicated that isoquercitrin inhibited H2O2-induced apoptosis of EA.hy926 cells. Western blotting demonstrated that isoquercitrin prevented H2O2-induced increases in cleaved caspase-9 and cleaved caspase-3 expression, while increasing expression of anti-apoptotic protein Mcl-1. Additionally, isoquercitrin significantly increased the expression of p-Akt and p-GSK3β in a dose-dependent manner in EA.hy926 cells. LY294002, a PI3K/Akt inhibitor, inhibited isoquercitrin-induced GSK3β phosphorylation and increase of Mcl-1 expression, which indicated that regulation of isoquercitrin on Mcl-1 expression was likely related to the modulation of Akt activation. These results demonstrated that the anti-apoptotic effect of isoquercitrin on H2O2-induced EA.hy926 cells was likely associated with the regulation of isoquercitrin on Akt/GSK3β signaling pathway and that isoquercitrin could be used clinically to interfere with the progression of endothelial injury-associated cardiovascular disease.

Myocardin-related transcription factor-A-overexpressing bone marrow stem cells protect cardiomyocytes and alleviate cardiac damage in a rat model of acute myocardial infarction.

Myocardin-related transcription factor-A (MRTF-A) can transduce biomechanical and humoral signals, which can positively modulate cardiac damage induced by acute myocardial infarction (AMI). In the clinic, bone marrow stem cell (BMSC) therapy is being increasingly utilized for AMI; however, the effects of BMSC transplantation remain to be optimized. Therefore, a novel strategy to enhance BMSC‑directed myocardial repair is particularly important. The present study was performed to assess the efficacy of MRTF‑A-overexpressing BMSCs in a rat model of AMI. Primary cardiomyocytes were prepared from neonatal Sprague-Dawley rats and BMSCs were isolated from male Sprague-Dawley rats (aged 8-12 weeks). Annexin V-phycoerythrin/7-actinomycin D staining was used to evaluate BMSC and cardiomyocyte survival after exposure to hydrogen peroxide in vitro. B-cell lymphoma 2 (Bcl-2) protein expression was measured by flow cytometric and western blot analyses. The effects of MRTF-A‑overexpressing BMSCs in a rat model of AMI were investigated by hematoxylin and eosin staining and western blot analysis of Bcl-2 expression in myocardial tissue sections. MRTF-A enhanced the migration of BMSCs, and overexpression of MRTF-A in BMSCs prevented hydrogen peroxide-induced apoptosis in primary cardiomyocytes ex vivo. In addition, co-culture of cardiomyocytes with MRTF‑A-overexpressing BMSCs inhibited hydrogen peroxide-induced apoptosis and the enhanced expression of Bcl-2. Furthermore, in vivo, enhanced cell survival was observed in the MRTF-A-modified BMSC group compared with that in the control group. These observations indicated that MRTF-A-overexpressing BMSCs have the potential to exert cardioprotective effects against hydrogen peroxide-induced injury and that treatment with MRTF‑A‑modified BMSCs is able to reverse cardiac dysfunction after AMI.

PED/PEA-15 inhibits hydrogen peroxide-induced apoptosis in Ins-1E pancreatic beta-cells via PLD-1.

The small scaffold protein PED/PEA-15 is involved in several different physiologic and pathologic processes, such as cell proliferation and survival, diabetes and cancer. PED/PEA-15 exerts an anti-apoptotic function due to its ability to interfere with both extrinsic and intrinsic apoptotic pathways in different cell types. Recent evidence shows that mice overexpressing PED/PEA-15 present larger pancreatic islets and increased beta-cells mass. In the present work we investigated PED/PEA-15 role in hydrogen peroxide-induced apoptosis in Ins-1E beta-cells. In pancreatic islets isolated from TgPED/PEA-15 mice hydrogen peroxide-induced DNA fragmentation was lower compared to WT islets. TUNEL analysis showed that PED/PEA-15 overexpression increases the viability of Ins-1E beta-cells and enhances their resistance to apoptosis induced by hydrogen peroxide exposure. The activity of caspase-3 and the cleavage of PARP-1 were markedly reduced in Ins-1E cells overexpressing PED/PEA-15 (Ins-1EPED/PEA-15). In parallel, we observed a decrease of the mRNA levels of pro-apoptotic genes Bcl-xS and Bad. In contrast, the expression of the anti-apoptotic gene Bcl-xL was enhanced. Accordingly, DNA fragmentation was higher in control cells compared to Ins-1EPED/PEA-15 cells. Interestingly, the preincubation with propranolol, an inhibitor of the pathway of PLD-1, a known interactor of PED/PEA-15, responsible for its deleterious effects on glucose tolerance, abolishes the antiapoptotic effects of PED/PEA-15 overexpression in Ins-1E beta-cells. The same results have been obtained by inhibiting PED/PEA-15 interaction with PLD-1 in Ins-1EPED/PEA-15. These results show that PED/PEA-15 overexpression is sufficient to block hydrogen peroxide-induced apoptosis in Ins-1E cells through a PLD-1 mediated mechanism.

Activated δ‑opioid receptors inhibit hydrogenperoxide‑induced apoptosis in liver cancer cells through the PKC/ERK signaling pathway.

Apoptotic liver cancer cells have important roles in liver tumorigenesis and liver cancer progression. Recent studies have shown that δ‑opioid receptors are highly expressed in human liver and liver cancer cells. The present study aimed to investigate the role of activated δ‑opioid receptors on human liver cancer cell apoptosis and its interrelation with the mitochondria and the protein kinaseC/extracellular‑signal‑regulated kinase (PKC/ERK) signaling pathway. H2O2 was used to induce apoptosis in human liver cancer cells. During apoptosis, mitochondrial transmembrane potentials were observed to decrease, cytochromec expression was found to increase and Bcell lymphoma2 (Bcl‑2) expression decreased. These findings suggested that H2O2‑induced apoptosis was mediated through the mitochondrial pathway. Of note, activated δ‑opioid receptors were observed to inhibit H2O2‑induced apoptosis in human liver cancer cells. Following δ‑opioid receptor activation, the number of apoptotic liver cancer cells decreased, mitochondrial transmembrane potentials were restored, cytoplasmic cytochromec and Bcl‑2‑associatedXprotein expression decreased and Bcl‑2 expression increased. These data suggested that δ‑opioid receptor activation inhibited mitochondria‑mediated apoptosis. In addition, activation of δ‑opioid receptors was observed to increase the expression of PKC and ERK in human liver cancer cells. Furthermore, upon inhibition of the PKC/ERK signaling pathway, the protective effect associated with the δ‑opioid receptor on liver cancer cell apoptosis was inhibited, which was not associated with the status of δ‑opioid receptor activation. These findings suggested that the PKC/ERK signaling pathway has an important role in δ‑opioid receptor‑mediated inhibition of apoptosis in human liver cancer cells.

(+)-Catechin protects dermal fibroblasts against oxidative stress-induced apoptosis

BackgroundOxidative stress has been suggested as a mechanism underlying skin aging, as it triggers apoptosis in various cell types, including fibroblasts, which play important roles in the preservation of healthy, youthful skin. Catechins, which are antioxidants contained in green tea, exert various actions such as anti-inflammatory, anti-bacterial, and anti-cancer actions. In this study, we investigated the effect of (+)-catechin on apoptosis induced by oxidative stress in fibroblasts.MethodsFibroblasts (NIH3T3) under oxidative stress induced by hydrogen peroxide (0.1 mM) were treated with either vehicle or (+)-catechin (0–100 μM). The effect of (+)-catechin on cell viability, apoptosis, phosphorylation of c-Jun terminal kinases (JNK) and p38, and activation of caspase-3 in fibroblasts under oxidative stress were evaluated.ResultsHydrogen peroxide induced apoptotic cell death in fibroblasts, accompanied by induction of phosphorylation of JNK and p38 and activation of caspase-3. Pretreatment of the fibroblasts with (+)-catechin inhibited hydrogen peroxide-induced apoptosis and reduced phosphorylation of JNK and p38 and activation of caspase-3.Conclusion(+)-Catechin protects against oxidative stress-induced cell death in fibroblasts, possibly by inhibiting phosphorylation of p38 and JNK. These results suggest that (+)-catechin has potential as a therapeutic agent for the prevention of skin aging.

Resveratrol Inhibits Hydrogen Peroxide-Induced Apoptosis in Endothelial Cells via the Activation of PI3K/Akt by miR-126

Resveratrol(RSV) is an edible polyphenolic phytoalexin present in different plant species that plays an important role in improving endothelial dysfunction. However, the molecular mechanisms underlying these effects are unknown. In the present study, the mechanism underlying the protection of CRL-1730 cells by RSV against oxidative stress was examined. We first assessed the effects of RSV on the cell viability and apoptosis of CRL-1730 cells exposed to hydrogen peroxide(H2O2). Real-time PCR was used to determine the microRNA-126(miR-126) expression in cells treated with RSV and/or H2O2. We also evaluated the PI3K/Akt signaling pathway in CRL-1730 cells following upregulation of the miR-126 expression. Finally, we determined the effects of miR-126 on RSV against oxidative injury using an miR-126 inhibitor. Treatment with RSV resulted in a significant increase in survival and a decrease in the apoptosis of CRL-1730 cells exposed to H2O2. We also found that H2O2 significantly suppressed the expression of miR-126, which was reversed by RSV in a dose-dependent manner. The overexpression of miR-126 decreased PIK3R2(p85-β) and enhanced Akt phosphorylation, which resulted in an increase in the survival of CRL-1730 cells exposed to H2O2. More importantly, the downregulation of the miR-126 expression reversed the effects of RSV on the survival and apoptosis of CRL-1730 cells exposed to H2O2. In addition, the knockdown of Ets-1 reversed the effects of RSV on the miR-126 expression in CRL-1730 cells exposed to H2O2. In this study, we demonstrated that the protection of endothelial cells by RSV against oxidative injury is due to the activation of PI3K/Akt by miR-126.

Wnt1 Inhibits Hydrogen Peroxide-Induced Apoptosis in Mouse Cardiac Stem Cells

BackgroundBecause of their regenerative and paracrine abilities, cardiac stem cells (CSCs) are the most appropriate, optimal and promising candidates for the development of cardiac regenerative medicine strategies. However, native and exogenous CSCs in ischemic hearts are exposed to various pro-apoptotic or cytotoxic factors preventing their regenerative and paracrine abilities.Methods and ResultsWe examined the effects of H2O2 on mouse CSCs (mCSCs), and observed that hydrogen peroxide (H2O2) treatment induces mCSCs apoptosis via the caspase 3 pathway, in a dose-dependent manner. We then examined the effects of Wnt1 over-expression on H2O2-induced apoptosis in mCSCs and observed that Wnt1 significantly decreased H2O2-induced apoptosis in mCSCs. On the other hand, inhibition of the canonical Wnt pathway by the secreted frizzled related protein 2 (SFRP2) or knockdown of β-catenin in mCSCs reduced cells resistance to H2O2-induced apoptosis, suggesting that Wnt1 predominantly prevents H2O2-induced apoptosis through the canonical Wnt pathway.ConclusionsOur results provide the first evidences that Wnt1 plays an important role in CSCs’ defenses against H2O2-induced apoptosis through the canonical Wnt1/GSK3β/β-catenin signaling pathway.

Par-4 gene silence inhibited hydrogen peroxide-induced apoptosis in alveolar epithelial cells

Objective To investigate the effects of Par-4 gene silence on hydrogen peroxide-induced apoptosis in alveolar epithelial cells. Method The alveolar epithelial cells A549 were cultured and exposed to hydrogen peroxide. The siRNA sequences targeted Par-4 gene was chemically synthesized and transfected to A549 cells with or without the exposure of hydrogen peroxide. The cells were divided into normal control groups, hydrogen peroxide-treated group(The cells were treated with 0. 1 mmol/L hydrogen peroxide), hydrogen peroxide and Par-4-siRNA-treated group(The cells were treated with 0. 1 mmol/L hydrogen peroxide after transfection of Par-4-siRNA), Non-specific DNA sequence transfection control group. The apoptosis of A549 cells was quantified by flow cytometry. The expression of Smac protein was detected by Western blot.Electrophoretic mobility shift assay was applied for evaluating the change of E2F1 DNA binding activity. Relative activity of Caspase-3 was detected by clolorimetric assay. Results The percent of apoptotic cells in hydrogen peroxide and Par-4-siRNA-treated group was (29.7 ± 2.3) %, which was significantly lower than that of hydrogen peroxide-treated group [(54.2 ± 4.1)%, q= 8.91, P ＜ 0.01)]. Par-4 siRNA could significantly suppress the increase of Smac protein, E2F1 DNA binding activity and caspase-3 activity induced by hydrogen peroxide in A549 cells. Conclusions Par-4 gene silence induced by siRNA might inhibit the apoptosis of alveolar epithelial cells, which might be resulted from suppression of the up-regulation of Smac gene expression, E2F1 DNA binding activity and caspase-3 activity. Key words: Par-4; Small RNA interference; Hydrogen peroxide; Alveolar epithelial cells; Apoptosis

Hispidin produced from Phellinus linteus protects pancreatic β-cells from damage by hydrogen peroxide

Phellinus linteus, which is a traditional medicinal mushroom used in Asian countries for the treatment of various diseases, has attracted a lot of attention due to its antioxidant, anti-inflammatory, anti-mutagenicity, and cell-mediated immunity properties in addition to its ability to inhibit tumor growth and metastasis. However, the antidiabetic efficacy of P. linteus has not yet been examined. In this study, hispidin from P. linteus exhibited quenching effects against DPPH radicals, superoxide radicals, and hydrogen peroxide in a dose-dependent manner. Intracellular reactive oxygen species scavenging activity of hispidin was approximately 55% at a concentration of 30 microM. In addition, hispidin was shown to inhibit hydrogen peroxide-induced apoptosis and increased insulin secretion in hydrogen peroxide-treated cells. These combined results indicate that hispidin may act as an antidiabetic and that this property occurs through preventing beta-cells from the toxic action of reactive oxygen species in diabetes.

Human papillomavirus type 16 E5 protein inhibits hydrogen peroxide-induced apoptosis by stimulating ubiquitin-proteasome-mediated degradation of Bax in human cervical cancer cells

To investigate the mechanism by which the human papillomavirus (HPV) E5 protein contributes to the carcinogenesis of uterine cervical cancer, we studied the effect of HPV E5 on apoptosis of cervical cancer cells and its underlying mechanism. Expression of HPV16 E5 protein inhibited hydrogen peroxide-induced apoptosis in C-33A cervical cancer cells. E5 decreased the expression of Bax protein, and exogenous expression of Bax abolished the anti-apoptotic effect of E5. Knockdown of E5 by small interfering RNA sensitized CaSki cervical cancer cells to hydrogen peroxide-induced apoptosis with concurrent increase in Bax expression. Transient expression of E5 significantly increased the degradation rate of Bax protein by inducing the ubiquitination. The E5-induced decrease in Bax expression was inhibited by a cyclooxygenase-2 (COX-2) inhibitor, prostaglandin E2 (PGE(2)) receptor antagonists and cyclic adenosine monophosphate-dependent protein kinase (PKA) inhibitor. Treatment with PGE(2) decreased the expression of Bax and inhibited hydrogen peroxide-induced apoptosis of C-33A cells. We concluded that HPV16 E5 protein inhibits hydrogen peroxide-induced apoptosis of cervical cancer cells by stimulating the ubiquitin-proteasome-mediated degradation of Bax protein, and the pathway involves COX-2, PGE(2) and PKA. This finding suggests the possibility that HPV 16 E5 protein contributes to cervical carcinogenesis by inhibiting apoptosis of transformed cervical epithelial cells.

Rutin inhibits hydrogen peroxide-induced apoptosis through regulating reactive oxygen species mediated mitochondrial dysfunction pathway in human umbilical vein endothelial cells

Apoptosis of human vein endothelium cell caused by reactive oxygen species is implicated in the pathogenesis of cardiovascular diseases. Rutin, an active flavonoid compound, is well known to possess potent antioxidant properties against oxidative stress insults through undefined mechanism(s). In this study, we first investigated the possible protective effects of rutin against apoptosis of human umbilical vein endothelial cells (HUVECs) induced by hydrogen peroxide (H 2O 2) and the associated signaling pathways. Decreased viability and increased apoptosis were observed in the HUVECs incubated with 200 μM H 2O 2 for 12 h. By examining the effect of rutin on H 2O 2-induced apoptosis in HUVECs, we found that rutin pretreatment significantly attenuated H 2O 2-induced apoptosis in HUVECs. We next examined the signaling involved in rutin-mediated anti-apoptotic effects. It was found that rutin pretreatment attenuated excessive reactive oxygen species in HUVECs exposed to H 2O 2. Rutin also prevented the increased DNA fragment formation and glutathione (GSH) depletion and inhibited the collapse of mitochondrial membrane potentials (ΔΨm) that occurred in HUVECs exposed to H 2O 2, which protected HUVECs against oxidative damage and the further mitochondrial membrane integrity impairment, leading to apoptosis. In conclusion, the results suggested that rutin (50 µM) blocked apoptosis in HUVECs through decreasing reactive oxygen species, increasing GSH, restoring ΔΨm and thus protecting DNA damage. Our research indicated that rutin protected the intracellular GSH antioxidant system and prevented H 2O 2-induced apoptosis of HUVECs through regulating reactive oxygen species mediated mitochondrial dysfunction pathway.

Inhibitory heterotrimeric GTP-binding proteins inhibit hydrogen peroxide-induced apoptosis by up-regulation of Bcl-2 via NF-κB in H1299 human lung cancer cells

Inhibitory heterotrimeric GTP-binding proteins (Gi proteins) mediate a variety of signaling pathways by coupling receptors and effectors to regulate cellular proliferation, differentiation, and apoptosis. However, the role of Gi proteins in the modulation of hydrogen peroxide-induced apoptosis is not clearly understood. Thus, we investigated the effect of Gi proteins on hydrogen peroxide-induced apoptosis and the underlying mechanisms in H1299 human lung cancer cells. The stable expression of constitutively active alpha subunits of Gi1 (Gαi1QL), Gi2, or Gi3 inhibited hydrogen peroxide-induced apoptosis. The expression of Gαi1QL up-regulated Bcl-2 expression, and the knockdown of Bcl-2 with siRNA abolished the anti-apoptotic effect of Gαi1QL. Gαi1 induced the transcription of Bcl-2 by activation of NF-κB, which resulted from an increase in NF-κB p50 protein. We conclude that Gαi1 inhibits hydrogen peroxide-induced apoptosis of H1299 lung cancer cells by up-regulating the transcription of Bcl-2 through a p50-mediated NF-κB activation.

Raloxifene analogue LY117018 suppresses oxidative stress-induced endothelial cell apoptosis through activation of ERK1/2 signaling pathway

A selective estrogen receptor modulator, raloxifene, has been shown to reduce cardiovascular events in relatively high-risk postmenopausal women with osteoporosis. However, the mechanisms by which raloxifene exerts a pharmacological effect on cardiovascular organs have not been fully elucidated. The present study was designed to examine whether the raloxifene analogue, 6-hydroxy-2-(p-hydroxyphenyl)-benzo(b) thien-3-yl-p-(2-(pyrrolidinyl)ethoxy phenyl ketone (LY117018), could inhibit apoptosis and to clarify the signaling pathway in vascular endothelial cells. LY117018 significantly inhibited hydrogen peroxide-induced apoptosis in bovine carotid artery endothelial cells. The anti-apoptotic effect of LY117018 was abolished by an estrogen receptor antagonist, 7α,7β-(9[(4,4,5,5,5-Pentafluoropentyl)sulfinyl]nonyl) estra-1,3,5(10)-triene-3,17-diol (ICI 182,780). Mitogen-activated protein kinases (MAPK), including p38, c-Jun N-terminal kinase (JNK) and extracellular signal-regulated protein kinase1/2 (ERK1/2), and Akt, have been shown to act as apoptotic or anti-apoptotic signals. Phosphorylation of p38, JNK, ERK1/2 and Akt was examined. LY117018 increased ERK1/2 phosphorylation but did not enhance the phosphorylation of p38, JNK, or Akt. The anti-apoptotic effect of LY117018 was prevented by treatment with 2-[2′-amino-3′-methoxyphenyl]-oxanaphthalen-4-one (PD98059), an upstream inhibitor of ERK1/2. LY117018 stimulated an increase in ERK1/2 phosphorylation, which was diminished by ICI 182,780. The activation of ERK/1/2 by LY117018 was not inhibited by the transcription inhibitor, actinomycin D. These results suggest that estrogen receptors and the ERK1/2 signaling pathway are involved in the anti-apoptotic action of LY117018 in vascular endothelial cells.