H2O2 induces a transient multi-phase cell cycle arrest in mouse fibroblasts through modulating cyclin D and p21Cip1 expression

Cold atmospheric plasma-activated medium for potential ovarian cancer therapy

Cold atmospheric plasma (CAP) has emerged as an innovative tool with broad medical applications, including ovarian cancer (OC) treatment. By bringing CAP in close proximity to liquids such as water or cell culture media, solutions containing reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated, called plasma-activated media (PAM). In this systematic review, we conduct an in-depth analysis of studies focusing on PAM interactions with biological substrates. We elucidate the diverse mechanisms involved in the activation of different media and the complex network of chemical reactions underlying the generation and consumption of the prominent reactive species. Furthermore, we highlight the promises of PAM in advancing biomedical applications, such as its stability for extended periods under appropriate storage conditions. We also examine the application of PAM as an anti-cancer and anti-metastatic treatment for OC, with a particular emphasis on its ability to induce apoptosis via distinct signaling pathways, inhibit cell growth, suppress cell motility, and enhance the therapeutic effects of chemotherapy. Finally, the future outlook of PAM therapy in biomedical applications is speculated, with emphasis on the safety issues relevant to clinical translation.

A coupled model between circadian, cell-cycle, and redox rhythms reveals their regulation of oxidative stress

Most organisms possess three biological oscillators, circadian clock, cell cycle, and redox rhythm, which are autonomous but interact each other. However, whether their interactions and autonomy are beneficial for organisms remains unclear. Here, we modeled a coupled oscillator system where each oscillator affected the phase of the other oscillators. We found that multiple types of coupling prevent a high H2O2 level in cells at M phase. Consequently, we hypothesized a high H2O2 sensitivity at the M phase and found that moderate coupling reduced cell damage due to oxidative stress by generating appropriate phase relationships between three rhythms, whereas strong coupling resulted in an elevated cell damage by increasing the average H2O2 level and disrupted the cell cycle. Furthermore, the multicellularity model revealed that phase variations among cells confer flexibility in synchronization with environments at the expense of adaptability to the optimal environment. Thus, both autonomy and synchrony among the oscillators are important for coordinating their phase relationships to minimize oxidative stress, and couplings balance them depending on environments.

Redox signaling-mediated tumor extracellular matrix remodeling: pleiotropic regulatory mechanisms

BACKGROUND

The extracellular matrix (ECM), a fundamental constituent of all tissues and organs, is crucial for shaping the tumor microenvironment. Dysregulation of ECM remodeling has been closely linked to tumor initiation and progression, where specific signaling pathways, including redox signaling, play essential roles. Reactive oxygen species (ROS) are risk factors for carcinogenesis whose excess can facilitate the oxidative damage of biomacromolecules, such as DNA and proteins. Emerging evidence suggests that redox effects can aid the modification, stimulation, and degradation of ECM, thus affecting ECM remodeling. These alterations in both the density and components of the ECM subsequently act as critical drivers for tumorigenesis. In this review, we provide an overview of the functions and primary traits of the ECM, and it delves into our current understanding of how redox reactions participate in ECM remodeling during cancer progression. We also discuss the opportunities and challenges presented by clinical strategies targeting redox-controlled ECM remodeling to overcome cancer.

CONCLUSIONS

The redox-mediated ECM remodeling contributes importantly to tumor survival, progression, metastasis, and poor prognosis. A comprehensive investigation of the concrete mechanism of redox-mediated tumor ECM remodeling and the combination usage of redox-targeted drugs with existing treatment means may reveal new therapeutic strategy for future antitumor therapies.

Cyclin D-CDK4 Disulfide Bond Attenuates Pulmonary Vascular Cell Proliferation

BACKGROUND

Pulmonary hypertension (PH) is a chronic vascular disease characterized, among other abnormalities, by hyperproliferative smooth muscle cells and a perturbed cellular redox and metabolic balance. Oxidants induce cell cycle arrest to halt proliferation; however, little is known about the redox-regulated effector proteins that mediate these processes. Here, we report a novel kinase-inhibitory disulfide bond in cyclin D-CDK4 (cyclin-dependent kinase 4) and investigate its role in cell proliferation and PH.

METHODS

Oxidative modifications of cyclin D-CDK4 were detected in human pulmonary arterial smooth muscle cells and human pulmonary arterial endothelial cells. Site-directed mutagenesis, tandem mass-spectrometry, cell-based experiments, in vitro kinase activity assays, in silico structural modeling, and a novel redox-dead constitutive knock-in mouse were utilized to investigate the nature and definitively establish the importance of CDK4 cysteine modification in pulmonary vascular cell proliferation. Furthermore, the cyclin D-CDK4 oxidation was assessed in vivo in the pulmonary arteries and isolated human pulmonary arterial smooth muscle cells of patients with pulmonary arterial hypertension and in 3 preclinical models of PH.

RESULTS

Cyclin D-CDK4 forms a reversible oxidant-induced heterodimeric disulfide dimer between C7/8 and C135, respectively, in cells in vitro and in pulmonary arteries in vivo to inhibit cyclin D-CDK4 kinase activity, decrease Rb (retinoblastoma) protein phosphorylation, and induce cell cycle arrest. Mutation of CDK4 C135 causes a kinase-impaired phenotype, which decreases cell proliferation rate and alleviates disease phenotype in an experimental mouse PH model, suggesting this cysteine is indispensable for cyclin D-CDK4 kinase activity. Pulmonary arteries and human pulmonary arterial smooth muscle cells from patients with pulmonary arterial hypertension display a decreased level of CDK4 disulfide, consistent with CDK4 being hyperactive in human pulmonary arterial hypertension. Furthermore, auranofin treatment, which induces the cyclin D-CDK4 disulfide, attenuates disease severity in experimental PH models by mitigating pulmonary vascular remodeling.

CONCLUSIONS

A novel disulfide bond in cyclin D-CDK4 acts as a rapid switch to inhibit kinase activity and halt cell proliferation. This oxidative modification forms at a critical cysteine residue, which is unique to CDK4, offering the potential for the design of a selective covalent inhibitor predicted to be beneficial in PH.

CDK4/6 inhibitor-mediated cell overgrowth triggers osmotic and replication stress to promote senescence

Abnormal increases in cell size are associated with senescence and cell cycle exit. The mechanisms by which overgrowth primes cells to withdraw from the cell cycle remain unknown. We address this question using CDK4/6 inhibitors, which arrest cells in G0/G1 and are licensed to treat advanced HR+/HER2- breast cancer. We demonstrate that CDK4/6-inhibited cells overgrow during G0/G1, causing p38/p53/p21-dependent cell cycle withdrawal. Cell cycle withdrawal is triggered by biphasic p21 induction. The first p21 wave is caused by osmotic stress, leading to p38- and size-dependent accumulation of p21. CDK4/6 inhibitor washout results in some cells entering S-phase. Overgrown cells experience replication stress, resulting in a second p21 wave that promotes cell cycle withdrawal from G2 or the subsequent G1. We propose that the levels of p21 integrate signals from overgrowth-triggered stresses to determine cell fate. This model explains how hypertrophy can drive senescence and why CDK4/6 inhibitors have long-lasting effects in patients.

Hydrogen peroxide signalling mediates fertilization and post-fertilization development in the red alga Bostrychia moritziana

Reactive oxygen species (ROS) signalling has a multitude of roles in cellular processes throughout biology. We hypothesized that red algal fertilization may offer an interesting model to study ROS-mediated signalling, as the stages of fertilization are complex and unique. We detected the localization of ROS production microscopically and monitored the expression of three homologues of NADPH oxidase in reproductive cells during fertilization. ROS were instantaneously produced by spermatia (sperm) when they attached to female trichogynes, diffused across the cell membrane in the form of H2O2, and triggered ROS generation in the carpogonium (egg) as well as carpogonial branch cells which are not in direct contact with spermatia. The expression of NADPH oxidase homologues, RESPIRATORY BURST OXIDASE HOMOLOGUES (BmRBOHs), began to be up-regulated in the female plant upon gamete binding, peaking during the fertilization process and descending back to their original level after fertilization. Pre-treatment with diphenylene iodonium or caffeine blocked gene expression as well as H2O2 production. Post-fertilization development was also inhibited when the redox state of the plants was perturbed with H2O2 at any time before or after the fertilization. Our results suggest that H2O2 acts as an auto-propagating signalling molecule, possibly through Ca2+ channel activation, and regulates gene expression in fertilization as well as post-fertilization development in red algae.

Piperlongumine promotes death of retinoblastoma cancer cells

Retinoblastoma is the most common pediatric intraocular malignant tumor. While retinoblastoma initiation is triggered by the inactivation of both alleles of the retinoblastoma tumor suppressor gene (RB1) in the developing retina, tumor progression requires additional epigenetic changes, retinoblastoma genomes being quite stable. Although the management of RB has recently improved, new therapeutic agents are necessary to improve the treatment of advanced forms of retinoblastoma.

In this report, we analyzed the pro-death effect of piperlongumine (PL), a natural compound isolated from Piper longum L., on two human retinoblastoma cell lines, WERI-Rb and Y79. The effects of PL on cell proliferation, cell death and cell cycle were investigated. PL effectively inhibited cell growth, impacted the cell cycle by decreasing the level of cyclins and CDK1 and increasing CDKN1A and triggered a caspase-3 independant cell death process in which reactive oxygen species (ROS) production is a major player. Indeed, PL toxicity in retinoblastoma cell lines was inhibited by a ROS scavenger N-acetyl-l-cysteine (NAC) treatment. These findings suggest that PL reduces tumor growth and induces cell death by regulating the cell cycle.

Cerium Oxide Nanoparticles: A New Therapeutic Tool in Liver Diseases

Oxidative stress induced by the overproduction of free radicals or reactive oxygen species (ROS) has been considered as a key pathogenic mechanism contributing to the initiation and progression of injury in liver diseases. Consequently, during the last few years antioxidant substances, such as superoxide dismutase (SOD), resveratrol, colchicine, eugenol, and vitamins E and C have received increasing interest as potential therapeutic agents in chronic liver diseases. These substances have demonstrated their efficacy in equilibrating hepatic ROS metabolism and thereby improving liver functionality. However, many of these agents have not successfully passed the scrutiny of clinical trials for the prevention and treatment of various diseases, mainly due to their unspecificity and consequent uncontrolled side effects, since a minimal level of ROS is needed for normal functioning. Recently, cerium oxide nanoparticles (CeO₂NPs) have emerged as a new powerful antioxidant agent with therapeutic properties in experimental liver disease. CeO₂NPs have been reported to act as a ROS and reactive nitrogen species (RNS) scavenger and to have multi-enzyme mimetic activity, including SOD activity (deprotionation of superoxide anion into oxygen and hydrogen peroxide), catalase activity (conversion of hydrogen peroxide into oxygen and water), and peroxidase activity (reducing hydrogen peroxide into hydroxyl radicals). Consequently, the beneficial effects of CeO₂NPs treatment have been reported in many different medical fields other than hepatology, including neurology, ophthalmology, cardiology, and oncology. Unlike other antioxidants, CeO₂NPs are only active at pathogenic levels of ROS, being inert and innocuous in healthy cells. In the current article, we review the potential of CeO₂NPs in several experimental models of liver disease and their safety as a therapeutic agent in humans as well.

Hyaluronic acid optimises therapeutic effects of hydrogen peroxide-induced oxidative stress on breast cancer

Distinguishing the multiple effects of reactive oxygen species (ROS) on cancer cells is important to understand their role in tumour biology. On one side, ROS can be oncogenic by promoting hypoxic conditions, genomic instability and tumorigenesis. Conversely, elevated levels of ROS-induced oxidative stress can induce cancer cell death. This is evidenced by the conflicting results of research using antioxidant therapy, which in some cases promoted tumour growth and metastasis. However, some antioxidative or ROS-mediated oxidative therapies have also yielded beneficial effects. To better define the effects of oxidative stress, in vitro experiments were conducted on 4T1 and splenic mononuclear cells (MNCs) under hypoxic and normoxic conditions. Furthermore, hydrogen peroxide (H₂ O₂ ; 10-1,000 μM) was used as an ROS source alone or in combination with hyaluronic acid (HA), which is frequently used as drug delivery vehicle. Our result indicated that the treatment of cancer cells with H₂ O₂  + HA was significantly more effective than H₂ O₂ alone. In addition, treatment with H₂ O₂  + HA led to increased apoptosis, decreased proliferation, and multiphase cell cycle arrest in 4T1 cells in a dose-dependent manner under normoxic or hypoxic conditions. As a result, migratory tendency and the messenger RNA levels of vascular endothelial growth factor, matrix metalloproteinase-2 (MMP-2), and MMP-9 were significantly decreased in 4T1 cells. Of note, HA treatment combined with 100-1,000 μM H₂ O₂ caused more damage to MNCs as compared to treatment with lower concentrations (10-50 μM). Based on these results, we propose to administer high-dose H₂ O₂  + HA (100-1000 μM) for intratumoural injection and low doses for systemic administration. Intratumoural route could have toxic and inhibitory effects not only on the tumour but also on residential myeloid cells defending it, whereas systemic treatment could stimulate peripheral immune responses against the tumour. More in vivo research is required to confirm this hypothesis.

Proteomics and phosphoproteomics study of LCMT1 overexpression and oxidative stress: overexpression of LCMT1 arrests H2O2-induced lose of cells viability

Objectives: Protein phosphatase 2A (PP2A), a major serine/threonine phosphatase, is also known to be a target of ROS. The methylation of PP2A can be catalyzed by leucine carboxyl methyltransferase-1 (LCMT1), which regulates PP2A activity and substrate specificity.

Methods: In the previous study, we have showed that LCMT1-dependent PP2Ac methylation arrests H₂O₂-induced cell oxidative stress damage. To explore the possible protective mechanism, we performed iTRAQ-based comparative quantitative proteomics and phosphoproteomics studies of H₂O₂-treated vector control and LCMT1-overexpressing cells.

Results: A total of 4480 non-redundant proteins and 3801 unique phosphopeptides were identified by this means. By comparing the H₂O₂-regulated proteins in LCMT1-overexpressing and vector control cells, we found that these differences were mainly related to protein phosphorylation, gene expression, protein maturation, the cytoskeleton and cell division. Further investigation of LCMT1 overexpression-specific regulated proteins under H₂O₂ treatment supported the idea that LCMT1 overexpression induced ageneral dephosphorylation of proteins and indicated increased expression of non-erythrocytic hemoglobin, inactivation of MAPK3 and regulation of proteins related to Rho signal transduction, which were known to be linked to the regulation of the cytoskeleton.

Discussion: These data provide proteomics and phosphoproteomics insights into the association of LCMT1-dependent PP2Ac methylation and oxidative stress and indirectly indicate that the methylation of PP2A plays an important role against oxidative stress.

Control of doxorubicin-induced, reactive oxygen-related apoptosis by glutathione peroxidase 1 in cardiac fibroblasts

Reactive oxygen formation plays a mechanistic role in the cardiotoxicity of doxorubicin, a chemotherapeutic agent that remains an important component of treatment programs for breast cancer and hematopoietic malignancies. To examine the role of doxorubicin-induced reactive oxygen species (ROS) in drug-related cardiac apoptosis, murine embryonic fibroblast cell lines were derived from the hearts of glutathione peroxidase 1 (Gpx-1) knockout mice. Cells from homozygous Gpx-1 knockout mice and parental animals were propagated with (Se+) and without (Se-) 100 nM sodium selenite. Activity levels of the peroxide detoxifying selenoprotein glutathione peroxidase (GSHPx) were marginally detectable (<1.6 nmol/min/mg) in fibroblasts from homozygous knockout animals whether or not cells were supplemented with selenium. GSHPx activity in Se- cells from parental murine fibroblasts was also <1.6 nmol/min/mg, whereas GSHPx levels in Se+ parental murine fibroblasts were 12.9 ± 2.7 nmol/min/mg (mean ± SE; P < 0.05). Catalase, superoxide dismutase, glutathione reductase, glutathione S-transferase, glucose 6-phosphate dehydrogenase, and reduced glutathione activities did not differ amongst the four cell lines. Reactive oxygen production increased from 908 ± 122 (arbitrary units) for untreated control cells to 1668 ± 54 following exposure to 1 μM doxorubicin for 24 h in parental fibroblasts not supplemented with selenium (P < 0.03); reactive oxygen formation in doxorubicin-treated parental fibroblasts propagated in selenium was 996 ± 69 (P = not significant compared to untreated control cells). Reactive oxygen levels in homozygous Gpx-1 knockout fibroblasts, irrespective of selenium supplementation status, were increased and equivalent to that in selenium deficient wild type fibroblasts. When cardiac fibroblasts were exposed to doxorubicin (0.05 μM) for 96 h and examined for cell cycle alterations by flow cytometry, and apoptosis by TUNEL assay, marked G2 arrest and TUNEL positivity were observed in knockout fibroblasts in the presence or absence of supplemental selenium, and in parental fibroblasts propagated without selenium. Parental fibroblasts propagated with selenium and exposed to the same concentration of doxorubicin demonstrated modest TUNEL positivity and substantially diminished amounts of low molecular weight DNA. These results were replicated in cardiac fibroblasts exposed to doxorubicin (1–2 μM) for 2 h (to mimic clinical drug dosing schedules) and examined 96 h following initiation of drug exposure. Doxorubicin uptake in cardiac fibroblasts was similar irrespective of the mRNA expression level or activity of GSHPx. These experiments suggest that the intracellular levels of doxorubicin-induced reactive oxygen species (ROS) are modulated by GSHPx and play an important role in doxorubicin-related apoptosis and altered cell cycle progression in murine cardiac fibroblasts.

Piperlongumine Induces Cell Cycle Arrest via Reactive Oxygen Species Accumulation and IKKβ Suppression in Human Breast Cancer Cells

Piperlongumine (PL), a natural product derived from long pepper (Piper longum L.), is known to exhibit anticancer effects. However, the effect of PL on cell cycle-regulatory proteins in estrogen receptor (ER)-positive breast cancer cells is unclear. Therefore, we investigated whether PL can modulate the growth of ER-positive breast cancer cell line, MCF-7. We found that PL decreased MCF-7 cell proliferation and migration. Flow cytometric analysis demonstrated that PL induced G2/M phase cell cycle arrest. Moreover, PL significantly modulated the mRNA levels of cyclins B1 and D1, cyclin-dependent kinases 1, 4, and 6, and proliferating cell nuclear antigen. PL induced intracellular reactive oxygen species (hydrogen peroxide) accumulation and glutathione depletion. PL-mediated inhibition of IKKβ expression decreased nuclear translocation of NF-κB p65. Furthermore, PL significantly increased p21 mRNA levels. In conclusion, our data suggest that PL exerts anticancer effects in ER-positive breast cancer cells by inhibiting cell proliferation and migration via ROS accumulation and IKKβ suppression.

Cerium oxide nanoparticles improve liver regeneration after acetaminophen-induced liver injury and partial hepatectomy in rats

Background and aims

Cerium oxide nanoparticles are effective scavengers of reactive oxygen species and have been proposed as a treatment for oxidative stress-related diseases. Consequently, we aimed to investigate the effect of these nanoparticles on hepatic regeneration after liver injury by partial hepatectomy and acetaminophen overdose.

Methods

All the in vitro experiments were performed in HepG2 cells. For the acetaminophen and partial hepatectomy experimental models, male Wistar rats were divided into three groups: (1) nanoparticles group, which received 0.1 mg/kg cerium nanoparticles i.v. twice a week for 2 weeks before 1 g/kg acetaminophen treatment, (2) N-acetyl-cysteine group, which received 300 mg/kg of N-acetyl-cysteine i.p. 1 h after APAP treatment and (3) partial hepatectomy group, which received the same nanoparticles treatment before partial hepatectomy. Each group was matched with vehicle-controlled rats.

Results

In the partial hepatectomy model, rats treated with cerium oxide nanoparticles showed a significant increase in liver regeneration, compared with control rats. In the acetaminophen experimental model, nanoparticles and N-acetyl-cysteine treatments decreased early liver damage in hepatic tissue. However, only the effect of cerium oxide nanoparticles was associated with a significant increment in hepatocellular proliferation. This treatment also reduced stress markers and increased cell cycle progression in hepatocytes and the activation of the transcription factor NF-κB in vitro and in vivo.

Conclusions

Our results demonstrate that the nanomaterial cerium oxide, besides their known antioxidant capacities, can enhance hepatocellular proliferation in experimental models of liver regeneration and drug-induced hepatotoxicity.

IL-2 Induces Transient Arrest in the G1 Phase to Protect Cervical Cancer Cells from Entering Apoptosis

Interleukin 2 (IL-2) has been used for the treatment of different types of cancer that express the IL-2 receptor (IL-2R). However, the effect of IL-2 on cervical cancer cells is unknown. IL-2R is present in normal cells of the immune system but not in the healthy cervix. We report that IL-2R is expressed in cervical cancer cells. IL-2 decreases cervical cancer cell proliferation via transient arrest of the G1 phase, which does not result in apoptosis or senescence. IL-2 upregulates the expression of p53 and p21 and downregulates cyclin D. In addition, we report the resistance of cervical cancer cells to treatments that induce apoptosis in HeLa and INBL cells. When arrested cells were treated with cisplatin, the cytokine protected cells from apoptosis induced by cisplatin. The effects of IL-2 on the cell cycle do not induce cellular senescence or activate the proapoptotic protein Bax. The cell arrest induced by IL-2 is conferring protection to cells against apoptosis.

On-off switching of cell cycle and melanogenesis regulation of melanocytes by non-thermal atmospheric pressure plasma-activated medium

Non-thermal atmospheric pressure (NAP) plasma has demonstrated potential in biomedical applications, such as cancer treatment, bactericidal sterilization, and cell growth promotion or inhibition. In this study, for the first time, we demonstrated on–off switching of cell cycle progression and regulated melanogenesis in normal human skin melanocytes by NAP plasma-activated medium (PAM). The melanocytes were exposed to NAP plasma at durations varying from 0 to 20 min, and the effects of PAM on cell proliferation, cell cycle progression, and melanogenesis were investigated. Although PAM showed no cytotoxicity, the proliferation of melanocytes was inhibited. The melanocyte cell cycle was arrested by PAM for a relatively short period (48 h), after which it recovered slowly. PAM promoted melanogenesis through the activation of the enzymes tyrosinase, tyrosinase-related protein-1, and tyrosinase-related protein-2. These effects seem to be related to reactive oxygen species induced by PAM. Our finding that PAM modulates the cell cycle may provide insight into the recurrence of cancer. The regulation of the melanogenesis of melanocytes may facilitate the control of skin tone without incurring negative side effects.

Cold atmospheric plasma treatment inhibits growth in colorectal cancer cells

Plasma oncology is a relatively new field of research. Recent developments have indicated that cold atmospheric plasma (CAP) technology is an interesting new therapeutic approach to cancer treatment. In this study, p53 wildtype (LoVo) and human p53 mutated (HT29 and SW480) colorectal cancer cells were treated with the miniFlatPlaSter - a device particularly developed for the treatment of tumor cells - that uses the Surface Micro Discharge (SMD) technology for plasma production in air. The present study analyzed the effects of plasma on colorectal cancer cells in vitro and on normal colon tissue ex vivo. Plasma treatment had strong effects on colon cancer cells, such as inhibition of cell proliferation, induction of cell death and modulation of p21 expression. In contrast, CAP treatment of murine colon tissue ex vivo for up to 2 min did not show any toxic effect on normal colon cells compared to H2O2 positive control. In summary, these results suggest that the miniFlatPlaSter plasma device is able to kill colorectal cancer cells independent of their p53 mutation status. Thus, this device presents a promising new approach in colon cancer therapy.

Human Placenta Hydrolysate Promotes Liver Regeneration via Activation of the Cytokine/Growth Factor-Mediated Pathway and Anti-oxidative Effect

Liver regeneration is a very complex process and is regulated by several cytokines and growth factors. It is also known that liver transplantation and the regeneration process cause massive oxidative stress, which interferes with liver regeneration. The placenta is known to contain various physiologically active ingredients such as cytokines, growth factors, and amino acids. In particular, human placenta hydrolysate (hPH) has been found to contain many amino acids. Most of the growth factors found in the placenta are known to be closely related to liver regeneration. Therefore, in this study, we investigated whether hPH is effective in promoting liver regeneration in rats undergoing partial hepatectomy. We confirmed that cell proliferation was significantly increased in HepG2 and human primary cells. Hepatocyte proliferation was also promoted in partial hepatectomized rats by hPH treatment. hPH increased liver regeneration rate, double nucleic cell ratio, mitotic cell ratio, proliferating cell nuclear antigen (PCNA), and K_i-67 positive cells in vivo as well as interleukin (IL)-6, tumor necrosis factor alpha (TNF-α), and hepatocyte growth factor (HGF). Moreover, Kupffer cells secreting IL-6 and TNF-α were activated by hPH treatment. In addition, hPH reduced thiobarbituric acid reactive substances (TBARs) and significantly increased glutathione (GSH), glutathione peroxidase (GPx), and superoxide dismutase (SOD). Taken together, these results suggest that hPH promotes liver regeneration by activating cytokines and growth factors associated with liver regeneration and eliminating oxidative stress.

Response of HepG2/C3A cells supplemented with sodium selenite to hydrogen peroxide-induced oxidative stress

Oxidative stress (OS) is involved in the onset of various pathological processes, and sodium selenite (Na₂SeO₃) is known to have antioxidant activity. This study evaluated the cellular response of human HepG2/C3A cells supplemented with Na₂SeO₃ when exposed to hydrogen peroxide (H₂O₂)-induced OS. We analyzed cytotoxicity, cell proliferation, and genotoxicity in comparison with molecular data of mRNA and protein expression. The MTT and comet assays revealed that Na₂SeO₃ conferred cytoprotective and anti-genotoxic effects. In contrast, RTCA (Real-Time Cell Analysis) and flow cytometry analysis revealed that Na₂SeO₃ did not inhibit H₂O₂-induced anti-proliferative effects or cell cycle arrest (G2/M). Cells exposed simultaneously to Na₂SeO₃ and H₂O₂ showed overexpression of GPX1 mRNA, indicating that Na₂SeO₃ influenced the cellular antioxidant system. Furthermore, downregulation of CAT mRNA and SOD1 and PRX2 proteins induced by H₂O₂, was minimal after the Na₂SeO₃+H₂O₂ treatment. Although normalization of CCN2B mRNA expression by Na₂SeO₃ was observed after the Na₂SeO₃+H₂O₂ treatment, this was not observed for other genes such as CDKN1A, CDKN1C, and CDKN2B, which are related to cell cycle control, nor for GADD45A, which is involved in the cellular response to DNA damage. Furthermore, both CDKN1B and CDKN1C expression were downregulated in HepG2/C3A cells treated with Na₂SeO₃ only. Our results indicate that cellular response to Na₂SeO₃ involved the modulation of the antioxidant system. Na₂SeO₃ was unable completely recover HepG2/C3A cells from H₂O₂-induced oxidative damage, as evidenced by analysis of cell proliferation kinetics, cell cycle assay, and expression of key genes involved in cell cycle progression and response to DNA damage.

Reactive oxygen species mediated placental oxidative stress, mitochondrial content, and cell cycle progression through mitogen-activated protein kinases in intrauterine growth restricted pigs

Intrauterine growth restriction (IUGR) remains a significant obstacle in pig production; however, information regarding the relationship between reactive oxygen species (ROS)-induced placental dysfunction and IUGR is still unknown. This study aimed to explore the placental redox status, mitochondrial content, cellular progression, and mitogen-activated protein kinase (MAPK) pathways in IUGR. Placental tissues were collected from normal intrauterine gestation (NIUG) and IUGR fetuses at delivery. Compared with the NIUG, placental ROS production, lipid peroxidation, and DNA damage were increased in IUGR. Placental mitochondrial DNA (mtDNA) content and mtDNA-encoded gene expression decreased in IUGR. Moreover, p21 phosphorylation increased, cyclin E expression decreased in IUGR cases, which showed senescence characteristics. Analysis of signaling pathways showed that the ERK1/2 phosphorylation increased whereas the p38 and JNK phosphorylation decreased in IUGR. In cultured porcine trophectoderm (pTr) cells, exogenous H₂O₂ increased intracellular ROS production, decreased cell viability in a dose-dependent manner. Cell cycle distribution was found to arrest in S and G2/M phases. Our findings suggested that IUGR was associated with greater placental ROS and oxidative injury, which might be a factor that resulted in lower mitochondrial content, microvilli loss and senescence, and activation of MAPK pathways.

Thymoquinone protects rat liver after partial hepatectomy under ischaemia/reperfusion through oxidative stress and endoplasmic reticulum stress prevention

Ischaemia reperfusion (I/R) is associated with liver injury and impaired regeneration during partial hepatectomy (PH). The aim of this study was to investigate the effect of thymoquinone (TQ), the active compound of essential oil obtained from Nigella sativa seeds, on rat liver after PH. Male Wistar rats were divided equally into four groups (n = 6) receiving an oral administration of either vehicle solution (sham and PH groups) or TQ at 30 mg/kg (TQ and TQ + PH groups) for 10 consecutive days. Then, rats underwent PH (70%) with 60 minutes of ischaemia followed by 24 hours of reperfusion (PH and TQ + PH groups). Alanine aminotransferase (ALT) activity and histopathological damage were determined. Also, antioxidant parameters, liver regeneration index, hepatic adenosine triphosphate (ATP) content, endoplasmic reticulum (ER) stress and apoptosis were assessed. In response to PH under I/R, liver damage was significantly alleviated by TQ treatment as evidenced by the decrease in ALT activity (P < .01) and histological findings (P < .001). In parallel, TQ preconditioning increased hepatic antioxidant capacities. Moreover, TQ improved mitochondrial function (ATP, P < .05), attenuated ER stress parameters and repressed the expression of apoptotic effectors. Taken together, our results suggest that TQ preconditioning could be an effective strategy to reduce liver injury after PH under I/R. The protective effects were mediated by the increase of antioxidant capacities and the decrease of ER stress and apoptosis.

Redox control in cancer development and progression

Cancer is the leading cause of death worldwide after cardiovascular diseases. This has been the case for the last few decades despite there being an increase in the number of cancer treatments. One reason for the apparent lack of drug effectiveness might be, at least in part, due to unspecificity for tumors; which often leads to substantial side effects. One way to improve the treatment of cancer is to increase the specificity of the treatment in accordance with the concept of individualized medicine. This will help to prevent further progression of an existing cancer or even to reduce the tumor burden. Alternatively it would be much more attractive and efficient to prevent the development of cancer in the first place. Therefore, it is important to understand the risk factors and the mechanisms of carcinogenesis in detail. One such risk factor, often associated with tumorigenesis and tumor progression, is an increased abundance of reactive oxygen species (ROS) arising from an imbalance of ROS-producing and -eliminating components. A surplus of ROS can induce oxidative damage of macromolecules including proteins, lipids and DNA. In contrast, ROS are essential for an adequate signal transduction and are known to regulate crucial cellular processes like cellular quiescence, differentiation and even apoptosis. Therefore, regulated ROS-formation at physiological levels can inhibit tumor formation and progression. With this review we provide an overview on the current knowledge of redox control in cancer development and progression.

Dietary resveratrol confers apoptotic resistance to oxidative stress in myoblasts

High levels of reactive oxygen species (ROS) contribute to muscle cell death in aging and disuse. We have previously found that resveratrol can reduce oxidative stress in response to aging and hindlimb unloading in rodents in vivo, but it was not known if resveratrol would protect muscle stem cells during repair or regeneration when oxidative stress is high. To test the protective role of resveratrol on muscle stem cells directly, we treated the C2C12 mouse myoblast cell line with moderate (100 μM) or very high (1 mM) levels of H2O2 in the presence or absence of resveratrol. The p21 promoter activity declined in myoblasts in response to high ROS, and this was accompanied a greater nuclear to cytoplasmic translocation of p21 in a dose-dependent matter in myoblasts as compared to myotubes. Apoptosis, as indicated by TdT-mediated dUTP nick-end labeling, was greater in C2C12 myoblasts as compared to myotubes (P<.05) after treatment with H2O2. Caspase-9, -8 and -3 activities were elevated significantly (P<.05) in myoblasts treated with H2O2. Myoblasts were more susceptible to ROS-induced oxidative stress than myotubes. We treated C2C12 myoblasts with 50 μM of resveratrol for periods up to 48 h to determine if myoblasts could be rescued from high-ROS-induced apoptosis by resveratrol. Resveratrol reduced the apoptotic index and significantly reduced the ROS-induced caspase-9, -8 and -3 activity in myoblasts. Furthermore, Bcl-2 and the Bax/Bcl-2 ratio were partially rescued in myoblasts by resveratrol treatment. Similarly, muscle stem cells isolated from mouse skeletal muscles showed reduced Sirt1 protein abundance with H2O2 treatment, but this could be reversed by resveratrol. Reduced apoptotic susceptibility in myoblasts as compared to myotubes to ROS is regulated, at least in part, by enhanced p21 promoter activity and nuclear p21 location in myotubes. Resveratrol confers further protection against ROS by improving Sirt1 levels and increasing antioxidant production, which reduces mitochondrial associated apoptotic signaling, and cell death in myoblasts.

Induction of transient cell cycle arrest by H2 O2 via modulation of ultradian oscillations of Hes1, Socs3, and p-Stat3 in fibroblast cells

Biological clocks, time-keeping systems, enable the living organisms to synchronize their biochemical processes with their environment. Among these molecular oscillators, ultradian oscillators have been identified with volatility less than 24 h. Transcription factor Hes1, a member of the basic Helix-loop-Helix (bHLH) protein family, has an oscillation duration of 2 h in vertebrates. Due to the pivotal role of oxidative stress in many human diseases, we evaluated the effect(s) of oxidative stress on Hes1 oscillator, its upstream regulators, and its downstream cell cycle regulators. NIH/3T3 mouse fibroblast cells were treated with sublethal (250 μM) and lethal (1000 μM) doses of H₂ O₂ for 30 min. H₂ O₂ generated a delay in p-Stat3 and Socs3 mRNAs followed by suppression of Hes1 protein. These events were accompanied by simultaneous upregulation of p21 and downregulation of cyclinD1, resulting in a temporary arrest of the cell cycle. In conclusion, the elimination of Hes1 protein oscillation by H₂ O₂ may represent a defense mechanism against oxidative stress in fibroblast cells.

The Protective Effect of Indole-3-Acetic Acid (IAA) on H2O2-Damaged Human Dental Pulp Stem Cells Is Mediated by the AKT Pathway and Involves Increased Expression of the Transcription Factor Nuclear Factor-Erythroid 2-Related Factor 2 (Nrf2) and Its Downstream Target Heme Oxygenase 1 (HO-1)

Indole-3-acetic acid (IAA) is the most common plant hormone of the auxin class and is known to have many effects including cell proliferation enhancement and antioxidant property. However, no study has revealed its defensive effects against oxidative toxicity in human dental pulp stem cells (hDPSCs). In this study, we investigated the effects of IAA on hydrogen peroxide- (H₂O₂-) induced oxidative toxicity in hDPSCs. H₂O₂-induced cytotoxicity was attenuated after IAA treatment. Cell cycle analysis using FACS showed that the damaged cell cycle and increased number of apoptotic cells by H₂O₂ treatment were recovered after the treatment of IAA. The H₂O₂-mediated increased expression of the proapoptotic genes, BAX and p53, was attenuated by IAA treatment, while IAA treatment increased antiapoptotic genes, BCL-2 and ATF5 expression. The increases of cleaved caspase-3 and ROS by H₂O₂ were also decreased after treatment of IAA. To further investigate the mechanism of IAA, Nrf2-related antioxidant pathway was examined and the results showed that the level of Nrf2 and HO-1 expressions, stimulated by H₂O_2, decreased after treatment of IAA. Moreover, IAA treatment protected hDPSCs against H₂O₂-induced oxidative stress via increased expression of Nrf2 and HO-1, mediated by the AKT pathway.

Fluctuation of ROS regulates proliferation and mediates inhibition of migration by reducing the interaction between DLC1 and CAV-1 in breast cancer cells

The aim of our present study was to elucidate the effects of up-regulation and down-regulation of intracellular reactive oxygen species (ROS) level on proliferation, migration, and related molecular mechanism. Breast cancer cells were treated by catalase or H₂O₂. MTT, colony formation assay, and Hoechst/PI staining were used to evaluate proliferation and apoptosis. The level of intracellular ROS was measured by dichlorodihydrofluorescein diacetate probes. The ability of migration was detected by wound healing. Western blotting and coimmunoprecipitation (co-IP) were used to determine the expression of DLC1 and CAV-1 and their interaction. Our data indicated that up-regulation of intracellular ROS induced by H₂O₂ significantly inhibited proliferation and induced apoptosis accompanying G1 cell cycle arrest and elevated expression of p53. For cell migration, either up-regulation or down-regulation of ROS induced migration inhibition with reduction of interaction between DLC1 and CAV-1. Our results suggested that up-regulation of intracellular ROS inhibited proliferation by promoting expression of p53 and induced G1 cycle arrest and apoptosis. Fluctuation of ROS inhibited migration through reducing the interaction between DLC1 and CAV-1.

Nrf2 modulates cell proliferation and antioxidants defenses during liver regeneration induced by partial hepatectomy

The objective was to determine the regulatory dynamic of Nrf2 during liver regeneration and the administration of EtOH and/or the G. schiedeanum extract. Male Wistar rats weighing 200-230 g were subjected to a 70% partial hepatectomy; they were then divided into three groups (groups 1-3). During the experiment, animals in Group 1 drank only water. The other two groups (2-3) received an intragastric dose of ethanol (1.5 g/kg BW, solution at 40% in isotonic saline solution). Additionally, rats in group 3 received a geranium extract daily at a dose of 300 mg/kg BW i.g. EtOh and/or Geranium schiedeanum was administered to rats with regenerating livers for 7 days. At the end of treatment, the activity was determined of the antioxidant enzymes, DNA concentration, TBARS, and TAC, in addition to the expression of Nrf-2, Cyclin D1, and Nqo1. EtOH increased ROS and Nrf-2, which activated the antioxidant defenses and delayed liver proliferation. On the other hand, Geranium schiedeanum exerted an antioxidant effect, diminishing ROS, but Nrf-2 expression increased, favoring liver proliferation through the increase of DNA concentration and the overexpression of Cyclin D1, however it did not activate the antioxidant defenses. In sum, it can be concluded that Nrf-2 possesses a regulatory dynamic that is evident in the presence of a toxic agent (EtOH) and/or a phytochemical agent with antioxidant capacity (Geranium schiedeanum) during liver regeneration.

SCFFbl12 Increases p21Waf1/Cip1 Expression Level through Atypical Ubiquitin Chain Synthesis

The cyclin-dependent kinase (CDK) inhibitor p21 is an unstructured protein regulated by multiple turnover pathways. p21 abundance is tightly regulated, and its defect causes tumor development. However, the mechanisms that underlie the control of p21 level are not fully understood. Here, we report a novel mechanism by which a component of the SCF ubiquitin ligase, Fbl12, augments p21 via the formation of atypical ubiquitin chains. We found that Fbl12 binds and ubiquitinates p21. Unexpectedly, Fbl12 increases the expression level of p21 by enhancing the mixed-type ubiquitination, including not only K48- but also K63-linked ubiquitin chains, followed by promotion of binding between p21 and CDK2. We also found that proteasome activator PA28γ attenuates p21 ubiquitination by interacting with Fbl12. In addition, UV irradiation induces a dissociation of p21 from Fbl12 and decreases K63-linked ubiquitination, leading to p21 degradation. These data suggest that Fbl12 is a key factor that maintains adequate intracellular concentration of p21 under normal conditions. Our finding may provide a novel possibility that p21's fate is governed by diverse ubiquitin chains.

Growth arrest of lung carcinoma cells (A549) by polyacrylate-anchored peroxovanadate by activating Rac1-NADPH oxidase signalling axis

Hydrogen peroxide is often required in sublethal, millimolar concentrations to show its oxidant effects on cells in culture as it is easily destroyed by cellular catalase. Previously, we had shown that diperoxovanadate, a physiologically stable peroxovanadium compound, can substitute H2O2 effectively in peroxidation reactions. We report here that peroxovanadate when anchored to polyacrylic acid (PAPV) becomes a highly potent inhibitor of growth of lung carcinoma cells (A549). The early events associated with PAPV treatment included cytoskeletal modifications, increase in GTPase activity of Rac1, accumulation of the reactive oxygen species, and also increase in phosphorylation of H2AX (γH2AX), a marker of DNA damage. These effects persisted even at 24 h after removal of the compound and culminated in increased levels of p53 and p21 together with growth arrest. The PAPV-mediated growth arrest was significantly abrogated in cells pre-treated with the N-acetylcysteine, Rac1 knocked down by siRNA and DPI an inhibitor of NADPH oxidase. In conclusion, our results show that polyacrylate derivative of peroxovanadate efficiently arrests growth of A549 cancerous cells by activating the axis of Rac1-NADPH oxidase leading to oxidative stress and DNA damage.

Curcuma longa polyphenols improve insulin-mediated lipid accumulation and attenuate proinflammatory response of 3T3-L1 adipose cells during oxidative stress through regulation of key adipokines and antioxidant enzymes

Plant polyphenols may exert beneficial action against obesity-related oxidative stress and inflammation which promote insulin resistance. This study evaluated the effect of polyphenols extracted from French Curcuma longa on 3T3-L1 adipose cells exposed to H2 O2 -mediated oxidative stress. We found that Curcuma longa extract exhibited high amounts of curcuminoids identified as curcumin, demethoxycurcumin, and bisdemethoxycurcumin, which exerted free radical-scavenging activities. Curcuma longa polyphenols improved insulin-mediated lipid accumulation and upregulated peroxisome proliferator-activated receptor-gamma gene expression and adiponectin secretion which decreased in H2 O2 -treated cells. Curcuminoids attenuated H2 O2 -enhanced production of pro-inflammatory molecules such as interleukin-6, tumor necrosis factor-alpha, monocyte chemoattractant protein-1, and nuclear factor κappa B. Moreover, they reduced intracellular levels of reactive oxygen species elevated by H2 O2 and modulated the expression of genes encoding superoxide dismutase and catalase antioxidant enzymes. Collectively, these findings highlight that Curcuma longa polyphenols protect adipose cells against oxidative stress and may improve obesity-related metabolic disorders. © 2016 BioFactors, 42(4):418-430, 2016.

Redox signaling, Nox5 and vascular remodeling in hypertension

Purpose of review

Extensive data indicate a role for reactive oxygen species (ROS) and redox signaling in vascular damage in hypertension. However, molecular mechanisms underlying these processes remain unclear, but oxidative post-translational modification of vascular proteins is critical. This review discusses how proteins are oxidatively modified and how redox signaling influences vascular smooth muscle cell growth and vascular remodeling in hypertension. We also highlight Nox5 as a novel vascular ROS-generating oxidase.

Recent findings

Oxidative stress in hypertension leads to oxidative imbalance that affects vascular cell function through redox signaling. Many Nox isoforms produce ROS in the vascular wall, and recent findings show that Nox5 may be important in humans. ROS regulate signaling by numerous processes including cysteine oxidative post-translational modification such as S-nitrosylation, S-glutathionylation and sulfydration. In vascular smooth muscle cells, this influences cellular responses to oxidative stimuli promoting changes from a contractile to a proliferative phenotype.

Summary

In hypertension, Nox-induced ROS production is increased, leading to perturbed redox signaling through oxidative modifications of vascular proteins. This influences mitogenic signaling and cell cycle regulation, leading to altered cell growth and vascular remodeling in hypertension.

Cyclin D type does not influence cell cycle response to DNA damage caused by ionizing radiation in multiple myeloma tumours

Multiple myeloma (MM) is characterized by over-expression of cyclin D1 (CCND1) or D2 (CCND2), which control G1 phase cell-cycle progression. Proteolytic degradation of CCND1 (but not CCND2), resulting in G1 arrest, is reported in non-MM cells post-DNA damage, affecting DNA repair and survival. We examined the effect of ionizing radiation (IR) on D-cyclin levels and cell-cycle kinetics of MM cells, exploring differences based on D-cyclin expression. We showed that CCND1 is downregulated, whereas CCND2 is not, following IR. This did not lead to hypo-phosphorylation of retinoblastoma protein or G1 arrest. Both CCND1- and CCND2-expressing MM cells arrested in S/G2/M, and did not differ in other cell-cycle proteins or sensitivity to IR. When treated with a CDK4/6 inhibitor, both CCND1 and CCND2 MM cells arrested in G1 and therefore are subject to physiological regulation at this checkpoint. Immunoprecipitation showed that, despite CCND1 degradation following IR, sufficient protein remains bound to CDK4/6 to prevent G1 arrest. Aberrant expression of CCND1 driven from the IGH promoter in t(11;14) MM cells maintains progression through G1 to arrest in S/G2/M. Differential expression of D-cyclin does not appear to affect cell-cycle response to IR, and is unlikely to underlie differential sensitivity to DNA damage.

Induction of S-Phase Arrest in Human Glioma Cells by Selenocysteine, a Natural Selenium-Containing Agent Via Triggering Reactive Oxygen Species-Mediated DNA Damage and Modulating MAPKs and AKT Pathways

Selenocysteine (SeC) a natural available selenoamino acid exhibits novel anticancer activities against human cancer cell lines. However, the growth inhibitory effect and mechanism of SeC in human glioma cells remain unclear. The present study reveals that SeC time- and dose-dependently inhibited U251 and U87 human glioma cells growth by induction of S-phase cell cycle arrest, followed by the marked decrease of cyclin A. SeC-induced S-phase arrest was achieved by inducing DNA damage through triggering generation of reactive oxygen species (ROS) and superoxide anion, with concomitant increase of TUNEL-positive cells and induction of p21waf1/Cip1 and p53. SeC treatment also caused the activation of p38MAPK, JNK and ERK, and inactivation of AKT. Four inhibitors of MAPKs and AKT pathways further confirmed their roles in SeC-induced S-phase arrest in human glioma cells. Our findings advance the understanding on the molecular mechanisms of SeC in human glioma management.

Control of Trx1 redox state modulates protection against methyl methanesulfonate-induced DNA damage via stabilization of p21

Thioredoxin 1 (Trx1) is known to play an important role in protecting against cell death. However, the mechanism for control of Trx1 in cell death resulting from DNA damage has not been fully investigated. In this study, we used the DNA-damaging agent methyl methanesulfonate (MMS) to investigate the protective effects of Trx1 against DNA damage and cell death in HEK293 cells. We found that MMS application caused dose-dependent changes in the Trx1 redox state determined by redox western blotting. At lower concentrations, both reduced and oxidized Trx1 were observed, whereas the reduced band was fully oxidized at the higher concentration. Trx1 overexpression and small interfering RNA knockdown in cells revealed that reduced Trx1 after exposure to lower doses of MMS attenuated DNA damage, assessed by comet assay, and level of the DNA-damage marker histone γ-H2AX, possibly through scavenging intracellular ROS and an increase in p21 protein level via enhancing its stability. However, oxidized Trx1 lost its protective ability to DNA damage in response to higher concentration of MMS. Corresponding to the redox state control of Trx1, cell death induced by different dose of MMS was also found, by inhibiting phosphorylations of p38 and 4E-BP1. These results indicate that reduced Trx1 plays important protective roles against MMS-induced DNA damage and cell death, suggesting that cell protection is regulated by the intracellular redox state. Control of the redox state of Trx1 and its regulating proteins may offer a novel therapeutic strategy for the control of cancer.

BRCA1 and BRCA2 protect against oxidative DNA damage converted into double-strand breaks during DNA replication

BRCA1 and BRCA2 mutation carriers are predisposed to develop breast and ovarian cancers, but the reasons for this tissue specificity are unknown. Breast epithelial cells are known to contain elevated levels of oxidative DNA damage, triggered by hormonally driven growth and its effect on cell metabolism. BRCA1- or BRCA2-deficient cells were found to be more sensitive to oxidative stress, modeled by treatment with patho-physiologic concentrations of hydrogen peroxide. Hydrogen peroxide exposure leads to oxidative DNA damage induced DNA double strand breaks (DSB) in BRCA-deficient cells causing them to accumulate in S-phase. In addition, after hydrogen peroxide treatment, BRCA deficient cells showed impaired Rad51 foci which are dependent on an intact BRCA1-BRCA2 pathway. These DSB resulted in an increase in chromatid-type aberrations, which are characteristic for BRCA1 and BRCA2-deficient cells. The most common result of oxidative DNA damage induced processing of S-phase DSB is an interstitial chromatid deletion, but insertions and exchanges were also seen in BRCA deficient cells. Thus, BRCA1 and BRCA2 are essential for the repair of oxidative DNA damage repair intermediates that persist into S-phase and produce DSB. The implication is that oxidative stress plays a role in the etiology of hereditary breast cancer.

Antioxidant polyphenol-rich extracts from the medicinal plants Antirhea borbonica, Doratoxylon apetalum and Gouania mauritiana protect 3T3-L1 preadipocytes against H2O2, TNFα and LPS inflammatory mediators by regulating the expression of superoxide dismutase and NF-κB genes

Background

Adipose cells responsible for fat storage are the targets of reactive oxygen species (ROS) like H₂O₂ and pro-inflammatory agents including TNFα and LPS. Such mediators contribute to oxidative stress and alter inflammatory processes in adipose tissue, leading to insulin resistance during obesity. Thus, the identification of natural compounds such as plant polyphenols able to increase the antioxidant and anti-inflammatory capacity of the body is of high interest. We aimed to evaluate the biological properties of polyphenol-rich extracts from the medicinal plants A. borbonica, D. apetalum and G. mauritiana on preadipocytes exposed to H₂O₂, TNFα or LPS mediators.

Methods

Medicinal plant extracts were analysed for their polyphenol contents by Folin-Ciocalteu and UPLC-ESI-MS methods as well as for their free radical-scavenging activities by DPPH and ORAC assays. To assess the ability of polyphenol-rich extracts to protect 3T3-L1 preadipocytes against H₂O₂, TNFα or LPS mediators, several parameters including cell viability (MTT and LDH assays), ROS production (DCFH-DA test), IL-6 and MCP-1 secretion (ELISA) were evaluated. Moreover, the expression of superoxide dismutase, catalase and NF-κB genes was explored (RT-QPCR).

Results

All medicinal plants exhibited high levels of polyphenols with free radical-scavenging capacities. Flavonoids such as quercetin, kaempferol, epicatechin and procyanidins, and phenolic acids derived from caffeic acid including chlorogenic acid, were detected. Polyphenol-rich plant extracts did not exert a cytotoxic effect on preadipocytes but protected them against H₂O₂ anti-proliferative action. Importantly, they down-regulated ROS production and the secretion of IL-6 and MCP-1 pro-inflammatory markers induced by H₂O₂, TNFα and LPS mediators. Such a protective action was associated with an increase in superoxide dismutase antioxidant enzyme gene expression and a decrease in mRNA levels of NF-κB pro-inflammatory transcription factor.

Conclusion

This study highlights that antioxidant strategies based on polyphenols derived from medicinal plants tested could contribute to regulate adipose tissue redox status and immune process, and thus participate to the improvement of obesity-related oxidative stress and inflammation.

Extracellular matrix modulates the biological effects of melatonin in mesenchymal stem cells

Both self-renewal and lineage-specific differentiation of mesenchymal stem cells (MSCs) are triggered by their in vivo microenvironment including the extracellular matrix (ECM) and secreted hormones. The ECM may modulate the physiological functions of hormones by providing binding sites and by regulating downstream signaling pathways. Thus, the purpose of this study was to evaluate the degree of adsorption of melatonin to a natural cell-deposited ECM and the effects of this interaction on the biological functions of melatonin in human bone marrow-derived MSCs (BM-MSCs). The fibrillar microstructure, matrix composition, and melatonin-binding affinity of decellularized ECM were characterized. The cell-deposited ECM improved melatonin-mediated cell proliferation by 31.4%, attenuated accumulation of intracellular reactive oxygen species accumulation, and increased superoxide dismutase (SOD) mRNA and protein expression. Interaction with ECM significantly enhanced the osteogenic effects of melatonin on BM-MSCs by increasing calcium deposition by 30.5%, up-regulating osteoblast-specific gene expression and down-regulating matrix metalloproteinase (MMP) expression. The underlying mechanisms of these changes in expression may involve intracellular antioxidant enzymes, because osteoblast-specific genes were down-regulated, whereas MMP expression was up-regulated, in the presence of SOD-specific inhibitors. Collectively, our findings indicate the importance of native ECM in modulating the osteoinductive and antioxidant effects of melatonin and provide a novel platform for studying the biological actions of growth factors or hormones in a physiologically relevant microenvironment. Moreover, a better understanding of the enhancement of MSC growth and osteogenic differentiation resulting from the combination of ECM and melatonin could improve the design of graft substitutes for skeletal tissue engineering.

In vitro toxicity evaluation of Ti(4+)-stabilized γ-Bi2O3 sillenites

We report results regarding the in vitro toxicology of γ-Bi2O3 represented by its isomorphous phase Bi12TiO20 (γ-BTO). The γ-BTO microparticles were synthesized by two methods: coprecipitation from a bismuth nitrate-tetrabutyl titanate solution and solid state reaction of Bi2O3 and TiO2 oxides. The structural and morphological characteristics of the obtained materials were determined using X-ray diffraction (XRD), selected area electron diffraction (SAED), transmission (TEM) and scanning (SEM) electron microscopy. The elemental composition was investigated using energy dispersive spectrometry (EDS). The cytotoxicity and oxidative/nitrosative stress (intracellular reactive oxygen species (ROS) and nitric oxide (NO) release) induced by the studied microparticles in HepG2, SH-SY5Y and 3T3-L1 cell cultures were determined using the MTT, DCF-DA (2',7'-dichlorfluorescein-diacetate) and Griess methods respectively. Depending on the cell type and γ-BTO concentration, results showed only weak cytotoxic effects after 24h of γ-BTO exposure and cell proliferation effects for longer treatment times. Only reduced NO release increases (corresponding to high γ-BTO concentrations) were detected in case of SH-SY5Y and 3T3-L1 cells. The intracellular ROS production (higher for HepG2 cells) appeared inversely proportional to the γ-BTO concentration. The obtained results indicated a promising in vitro biocompatibility of γ-BTO and encourage further studies regarding its potential for biomedical applications.

Reactive oxygen species regulate the quiescence of CD34-positive cells derived from human embryonic stem cells

AIMS

Reactive oxygen species (ROS) are involved in a wide range of cellular processes. However, few studies have examined the generation and function of ROS in human embryonic vascular development. In this study, the sources of ROS and their roles in the vascular differentiation of human embryonic stem cells (hESCs) were investigated.

METHODS AND RESULTS

During vascular differentiation of hESCs, CD34(+) cells had quiescence-related gene expression profiles and a large fraction of these cells were in G0 phase. In addition, levels of ROS, which were primarily generated through NOX4, were substantially higher in hESC-derived CD34(+) cells than in hESC-derived CD34(-) cells. To determine whether excess levels of ROS induce quiescence of hESC-derived CD34(+) cells, ROS levels were moderately reduced using selenium to enhance antioxidant activities of thioredoxin reductase and glutathione peroxidase. In comparison to untreated CD34(+) cells, selenium-treated CD34(+) cells exhibited changes in gene expression that favoured cell cycle progression, and had a greater proliferation and a smaller fraction of cells in G0 phase. Thus, selenium treatment increased the number of hESC-derived CD34(+) cells, thereby enhancing the efficiency with which hESCs differentiated into vascular endothelial and smooth muscle cells.

CONCLUSION

This study reveals that NOX4 produces ROS in CD34(+) cells during vascular differentiation of hESCs, and shows that modulation of ROS levels using antioxidants such as selenium may be a novel approach to increase the vascular differentiation efficiency of hESCs.

p38 MAPK: a dual role in hepatocyte proliferation through reactive oxygen species

p38 MAPKs are important mediators of signal transduction that respond to a wide range of extracellular stressors such as UV radiation, osmotic shock, hypoxia, pro-inflammatory cytokines, and oxidative stress. The most abundant family member is p38α, which helps to couple cell proliferation and growth in response to certain damaging stimuli. In fact, increased proliferation and impaired differentiation are hallmarks of p38α-deficient cells. It has been reported that reactive oxygen species (ROS) play a critical role in cytokine-induced p38α activation. Under physiological conditions, p38α can function as a mediator of ROS signaling and either activate or suppress cell cycle progression depending on the activation stimulus. The interplay between cell proliferation, p38 MAPK activation, and ROS production plays an important role in hepatocytes. In fact, low levels of ROS seem to be needed to activate several signaling pathways in response to hepatectomy and to orchestrate liver regeneration. p38 MAPK works as a sensor of oxidative stress and cells that have developed mechanisms to uncouple p38 MAPK activation from oxidative stress are more likely to become tumorigenic. So far, p38α influences the redox balance, determining cell survival, terminal differentiation, proliferation, and senescence. Further studies would be necessary in order to clarify the precise role of p38 MAPK signaling as a redox therapeutical target.

Endometriosis-associated ovarian cancer: a review of pathogenesis

Endometriosis is classically defined as the presence of endometrial glands and stroma outside of the endometrial lining and uterine musculature. With an estimated frequency of 5%–10% among women of reproductive age, endometriosis is a common gynecologic disorder. While in itself a benign lesion, endometriosis shares several characteristics with invasive cancer, has been shown to undergo malignant transformation, and has been associated with an increased risk of epithelial ovarian carcinoma (EOC). Numerous epidemiologic studies have shown an increased risk of EOC among women with endometriosis. This is particularly true for women with endometrioid and clear cell ovarian carcinoma. However, the carcinogenic pathways by which endometriosis associated ovarian carcinoma (EAOC) develops remain poorly understood. Current molecular studies have sought to link endometriosis with EAOC through pathways related to oxidative stress, inflammation and hyperestrogenism. In addition, numerous studies have sought to identify an intermediary lesion between endometriosis and EAOC that may allow for the identification of endometriosis at greatest risk for malignant transformation or for the prevention of malignant transformation of this common gynecologic disorder. The objective of the current article is to review the current data regarding the molecular events associated with EAOC development from endometriosis, with a primary focus on malignancies of the endometrioid and clear cell histologic sub-types.

Antioxidative, antiapoptotic, and proliferative effect of curcumin on liver regeneration after partial hepatectomy in rats

The aim of the present study was to assess the influence of curcumin on liver regeneration after partial hepatectomy (PH) in rats. A total of 24 male Sprague Dawley rats were divided into three groups: sham-operated (SH), PH, and PH + curcumin; each group contains eight animals. The rats in curcumin-treated groups were given curcumin (in a dose of 100 mg/kg body weight) once a day orally for 7 days, starting 3 days prior to hepatectomy operation. At 7 days after resection, liver samples were collected. The malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH) levels were estimated in liver homogenates. Moreover, histopathological examination, mitotic index (MI), proliferating cell nuclear antigen labeling, proliferation index (PI), transferase-mediated 2'-deoxyuridine, 5'-triphosphate nick end-labeling assay, and apoptotic index (AI) were evaluated at 7 days after hepatectomy. As a result, curcumin significantly increased MI and PI and significantly decreased AI in PH rats. Additionally, curcumin remarkably inhibited MDA elevation, restored impaired antioxidant SOD activity and GSH level and also attenuated hepatic vacuolar degeneration and sinusoidal congestion. These results suggested that curcumin treatment had a beneficial effect on liver regenerative capacity of the remnant liver tissue after hepatectomy, probably due to its antioxidative, antiapoptotic, and proliferative properties.