Induction of apoptosis in a human leukemic cell line via reactive oxygen species modulation by antioxidants

Sodium arsenite and arsenic trioxide differently affect the oxidative stress of lymphoblastoid cells: An intricate crosstalk between mitochondria, autophagy and cell death

Although the toxicity of arsenic depends on its chemical forms, few studies have taken into account the ambiguous phenomenon that sodium arsenite (NaAsO2) acts as a potent carcinogen while arsenic trioxide (ATO, As2O3) serves as an effective therapeutic agent in lymphoma, suggesting that NaAsO2 and As2O3 may act via paradoxical ways to either promote or inhibit cancer pathogenesis. Here, we compared the cellular response of the two arsenical compounds, NaAsO2 and As2O3, on the Burkitt lymphoma cell model, the Epstein Barr Virus (EBV)-positive P3HR1 cells. Using flow cytometry and biochemistry analyses, we showed that a NaAsO2 treatment induces P3HR1 cell death, combined with drastic drops in ΔΨm, NAD(P)H and ATP levels. In contrast, As2O3-treated cells resist to cell death, with a moderate reduction of ΔΨm, NAD(P)H and ATP. While both compounds block cells in G2/M and affect their protein carbonylation and lipid peroxidation, As2O3 induces a milder increase in superoxide anions and H2O2 than NaAsO2, associated to a milder inhibition of antioxidant defenses. By electron microscopy, RT-qPCR and image cytometry analyses, we showed that As2O3-treated cells display an overall autophagic response, combined with mitophagy and an unfolded protein response, characteristics that were not observed following a NaAsO2 treatment. As previous works showed that As2O3 reactivates EBV in P3HR1 cells, we treated the EBV- Ramos-1 cells and showed that autophagy was not induced in these EBV- cells upon As2O3 treatment suggesting that the boost of autophagy observed in As2O3-treated P3HR1 cells could be due to the presence of EBV in these cells. Overall, our results suggest that As2O3 is an autophagic inducer which action is enhanced when EBV is present in the cells, in contrast to NaAsO2, which induces cell death. That's why As2O3 is combined with other chemicals, as all-trans retinoic acid, to better target cancer cells in therapeutic treatments.

Peroxiredoxin 3 Has Important Roles on Arsenic Trioxide Induced Apoptosis in Human Acute Promyelocytic Leukemia Cell Line via Hyperoxidation of Mitochondrial Specific Reactive Oxygen Species

NB4 cell, the human acute promyelocytic leukemia (APL) cell line, was treated with various concentrations of arsenic trioxide (ATO) to induce apoptosis, measured by staining with 7-amino-actinomycin D (7-AAD) by flow cytometry. 2', 7'-dichlorodihydro-fluorescein-diacetate (DCF-DA) and MitoSOXTM Red mitochondrial superoxide indicator were used to detect intracellular and mitochondrial reactive oxygen species (ROS). The steady-state level of SO2 (Cysteine sulfinic acid, Cys-SO2H) form for peroxiredoxin 3 (PRX3) was measured by a western blot. To evaluate the effect of sulfiredoxin 1 depletion, NB4 cells were transfected with small interfering RNA and analyzed for their influence on ROS, redox enzymes, and apoptosis. The mitochondrial ROS of NB4 cells significantly increased after ATO treatment. NB4 cell apoptosis after ATO treatment increased in a time-dependent manner. Increased SO2 form and dimeric PRX3 were observed as a hyperoxidation reaction in NB4 cells post-ATO treatment, in concordance with mitochondrial ROS accumulation. Sulfiredoxin 1 expression is downregulated by small interfering RNA transfection, which potentiated mitochondrial ROS generation and cell growth arrest in ATO-treated NB4 cells. Our results indicate that ATO-induced ROS generation in APL cell mitochondria is attributable to PRX3 hyperoxidation as well as dimerized PRX3 accumulation, subsequently triggering apoptosis. The downregulation of sulfiredoxin 1 could amplify apoptosis in ATO-treated APL cells.

Astaxanthin Modulates Apoptotic Molecules to Induce Death of SKBR3 Breast Cancer Cells

Astaxanthin (AST) is related to apoptosis but the details of the mechanism of how AST makes apoptosis is not clear. The present study investigated apoptotic effects of AST to SKBR3, a breast cancer cell line in detail. Cell viability assay showed cellular proliferation and morphological changes of the cells were observed under AST treatment. FACS analysis indicated that AST blocked cell cycle progression at G0/G1, suppressed proliferation dose-dependently, and induced apoptosis of the cells. The apoptosis of the cells by AST was further demonstrated through the decreased expression level of mutp53 and cleaved a PARP-1 fragment, respectively. In addition, AST induced the intrinsic apoptosis of the cells by activation of Bax/Bcl2, cleaved caspase-3, and cleaved caspase-9 as well as the phosphorylation of ERK1/2, JNK, and p38. Furthermore, AST decreased production of intracellular reactive oxygen species as well as modulated expressions of superoxide dismutases and Pontin, an anti-apoptotic factor. Co-immunoprecipitation assay revealed AST reduced interaction between Pontin and mutant p53. Taken together, these studies proved that AST regulates the expression of apoptotic molecules to induce intrinsic apoptosis of the cells, suggesting AST therapy might provide an alternative for improving the efficacies of other anti-cancer therapies for breast cancer.

Peroxiporins in Cancer

The transport of H₂O₂ across membranes by specific aquaporins (AQPs) has been considered the last milestone in the timeline of hydrogen peroxide discoveries in biochemistry. According to its concentration and localization, H₂O₂ can be dangerous or acts as a signaling molecule in various cellular processes as either a paracrine (intercellular) and/or an autocrine (intracellular) signal. In this review, we investigate and critically examine the available information on AQP isoforms able to facilitate H₂O₂ across biological membranes (“peroxiporins”), focusing in particular on their role in cancer. Moreover, the ability of natural compounds to modulate expression and/or activity of peroxiporins is schematically reported and discussed.

Protective skin aging effects of cherry blossom extract (Prunus Yedoensis) on oxidative stress and apoptosis in UVB-irradiated HaCaT cells

Extracts of the cherry blossom plant have been reported to exert various biological effects on human cells. However, no previous investigations have examined the antioxidant and anti-apoptotic effects of these extracts on ultraviolet B (UVB) radiation-induced skin aging. This study explores the underlying mechanisms of the antioxidant and anti-apoptotic effects of cherry blossom extract (CBE) in human keratinocyte (HaCaT) cells. HaCaT cells were treated with CBE at concentrations of 0.5, 1.0, and 2.0% for 24 h and then irradiated with UVB (40 mJ/cm²). CBE effectively and dose-dependently decreased the levels of reactive oxygen species and malondialdehyde, while increasing the activities of superoxide dismutase and glutathione peroxidase. Pretreatment with 1 and 2% CBE attenuated UVB-induced DNA damage by reducing the formation of cyclobutane pyrimidine dimers and 8-hydroxy-20-deoxyguanosine. Furthermore, CBE also prevented UVB-induced apoptosis and significantly downregulated B cell lymphoma 2 (Bcl-2)-associated X, cytochrome-c, and caspase-3 expression, while upregulating Bcl-2 expression. Taken together, these results indicate that CBE protects HaCaT cells from UVB-induced oxidative stress and apoptosis and suggest that CBE could be a potent antioxidant against skin aging.

Glycosides from Stevia rebaudiana Bertoni Possess Insulin-Mimetic and Antioxidant Activities in Rat Cardiac Fibroblasts

Stevia rebaudiana Bertoni is a shrub having a high content of sweet diterpenoid glycosides in its leaves, mainly stevioside and rebaudioside A, which are used as noncaloric, natural sweeteners. The aim of this study was to deepen the knowledge about the insulin-mimetic effect exerted by four different mixtures of steviol glycosides, rich in stevioside and rebaudioside A, in neonatal rat cardiac fibroblasts. The potential antioxidant activity of these steviol glycosides was also assessed, as oxidative stress is associated with diabetes. Likewise the insulin effect, steviol glycosides caused an increase in glucose uptake into rat fibroblasts by activating the PI3K/Akt pathway, thus inducing Glut4 translocation to the plasma membrane. The presence of S961, an insulin antagonist, completely abolished these effects, allowing to hypothesize that steviol glycosides could act as ligands of the same receptor engaged by insulin. Moreover, steviol glycosides counteracted oxidative stress by increasing reduced glutathione intracellular levels and upregulating expression and activity of the two antioxidant enzymes superoxide dismutase and catalase. The present work unravels the insulin-mimetic effect and the antioxidant property exerted by steviol glycosides, suggesting their potential beneficial role in the cotreatment of diabetes and in health maintenance.

2-SeCD treatment extends lifespan, improves healthspan and enhances resistance to stress in Caenorhabditis elegans

Aging is primarily caused by reactive oxygen species (ROS).

Myeloid-derived suppressor cells: their role in the pathophysiology of hematologic malignancies and potential as therapeutic targets

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells at various stages of differentiation/maturation that have a role in cancer induction and progression. They function as vasculogenic and immunosuppressive cells, utilizing multiple mechanisms to block both innate and adaptive anti-tumor immunity. Recently, their mechanism of action and clinical importance have been defined, and the cross-talk between myeloid cells and cancer cells has been shown to contribute to tumor induction, progression, metastasis and tolerance. In this review, we focus on the role of MDSCs in hematologic malignancies and the therapeutic approaches targeting MDSCs that are currently in clinical studies.

ROS, Notch, and Wnt signaling pathways: crosstalk between three major regulators of cardiovascular biology

Reactive oxygen species (ROS), traditionally viewed as toxic by-products that cause damage to biomolecules, now are clearly recognized as key modulators in a variety of biological processes and pathological states. The development and regulation of the cardiovascular system require orchestrated activities; Notch and Wnt/β-catenin signaling pathways are implicated in many aspects of them, including cardiomyocytes and smooth muscle cells survival, angiogenesis, progenitor cells recruitment and differentiation, arteriovenous specification, vascular cell migration, and cardiac remodelling. Several novel findings regarding the role of ROS in Notch and Wnt/β-catenin modulation prompted us to review their emerging function in the cardiovascular system during embryogenesis and postnatally.

Induction of apoptosis in human multiple myeloma cell lines by ebselen via enhancing the endogenous reactive oxygen species production

Ebselen a selenoorganic compound showing glutathione peroxidase like activity is an anti-inflammatory and antioxidative agent. Its cytoprotective activity has been investigated in recent years. However, experimental evidence also shows that ebselen causes cell death in several cancer cell types whose mechanism has not yet been elucidated. In this study, we examined the effect of ebselen on multiple myeloma (MM) cell lines in vitro. The results showed that ebselen significantly enhanced the production of reactive oxygen species (ROS) accompanied by cell viability decrease and apoptosis rate increase. Further studies revealed that ebselen can induce Bax redistribution from the cytosol to mitochondria leading to mitochondrial membrane potential ΔΨm changes and cytochrome C release from the mitochondria to cytosol. Furtherly, we found that exogenous addition of N-acetyl cysteine (NAC) completely diminished the cell damage induced by ebselen. This result suggests that relatively high concentration of ebselen can induce MM cells apoptosis in culture by enhancing the production of endogenous ROS and triggering mitochondria mediated apoptotic pathway.

Novel roles of reactive oxygen species in the pathogenesis of acute myeloid leukemia

It has become apparent that regulation of ROS is important in cell signaling and homeostasis. Accumulation of ROS triggers oxidative stress in various cell types and contributes to the development, progression, and persistence of cancer. Recent research has demonstrated that redox dysregulation caused by ROS promotes proliferation, differentiation, genomic, and epigenetic alterations; immune evasion; and survival in leukemic cells. ROS act as signaling molecules to regulate redox-sensitive transcriptional factors, enzymes, oncogenes, and other downstream effectors. Thus, a thorough understanding the role of ROS as key mediators in leukemogenesis is likely to provide opportunities for improved pharmacological intervention. In this review, we summarize the recent findings that support a role for ROS in the pathogenesis of AML and outline innovative approaches in the implementation of redox therapies for myeloid malignancies.

Dietary phenolic acids act as effective antioxidants in membrane models and in cultured cells, exhibiting proapoptotic effects in leukaemia cells

Caffeic, syringic, and protocatechuic acids are phenolic acids derived directly from food intake or come from the gut metabolism of polyphenols. In this study, the antioxidant activity of these compounds was at first evaluated in membrane models, where caffeic acid behaved as a very effective chain-breaking antioxidant, whereas syringic and protocatechuic acids were only retardants of lipid peroxidation. However, all three compounds acted as good scavengers of reactive species in cultured cells subjected to exogenous oxidative stress produced by low level of H(2)O(2). Many tumour cells are characterised by increased ROS levels compared with their noncancerous counterparts. Therefore, we investigated whether phenolic acids, at low concentrations, comparable to those present in human plasma, were able to decrease basal reactive species. Results show that phenolic acids reduced ROS in a leukaemia cell line (HEL), whereas no effect was observed in normal cells, such as HUVEC. The compounds exhibited no toxicity to normal cells while they decreased proliferation in leukaemia cells, inducing apoptosis. In the debate on optimal ROS-manipulating strategies in cancer therapy, our work in leukaemia cells supports the antioxidant ROS-depleting approach.

NOX2-derived reactive oxygen species are crucial for CD29-induced pro-survival signalling in cardiomyocytes

AIMS

The highly expressed cell adhesion receptor CD29 (β(1)-integrin) is essential for cardiomyocyte growth and survival, and its loss of function causes severe heart disease. However, CD29-induced signalling in cardiomyocytes is ill defined and may involve reactive oxygen species (ROS). A decisive source of cardiac ROS is the abundant NADPH oxidase (NOX) isoform NOX2. Because understanding of NOX-derived ROS in the heart is still poor, we sought to test the role of ROS and NOX in CD29-induced survival signalling in cardiomyocytes.

METHODS AND RESULTS

In neonatal rat ventricular myocytes, CD29 activation induced intracellular ROS formation (oxidative burst) as assessed by flow cytometry using the redox-sensitive fluorescent dye dichlorodihydrofluorescein diacetate. This burst was inhibited by apocynin and diphenylene iodonium. Further, activation of CD29 enhanced NOX activity (lucigenin-enhanced chemiluminescence) and activated the MEK/ERK and PI3K/Akt survival pathways. CD29 also induced phosphorylation of the inhibitory Ser9 on the pro-apoptotic kinase glycogen synthase kinase-3β in a PI3K/Akt- and MEK-dependent manner, and improved cardiomyocyte viability under conditions of oxidative stress. The ROS scavenger MnTMPyP or adenoviral co-overexpression of the antioxidant enzymes superoxide dismutase and catalase inhibited CD29-induced pro-survival signalling. Further, CD29-induced protective pathways were lost in mouse cardiomyocytes deficient for NOX2 or functional p47(phox), a regulatory subunit of NOX.

CONCLUSION

p47(phox)-dependent, NOX2-derived ROS are mandatory for CD29-induced pro-survival signalling in cardiomyocytes. These findings go in line with a growing body of evidence suggesting that ROS can be beneficial to the cell and support a crucial role for NOX2-derived ROS in cell survival in the heart.

Interconverting flavanone glucosides and other phenolic compounds in Lippia salviaefolia Cham. ethanol extracts

Four interconverting flavanone glycosides [(2R)- and (2S)-3',4',5,6-tetrahydroxyflavanone 7-O-β-D-glucopyranoside, and (2R)- and (2S)-3',4',5,8-tetrahydroxyflavanone 7-O-β-D-glucopyranoside], in addition to eight known flavonoids [naringenin, asebogenin, sakuranetin, 6-hydroxyluteolin 7-O-β-D-glucoside, (2R)- and (2S)-eriodictyol 7-O-β-D-glucopyranoside, aromadendrin and phloretin], three phenylpropanoid glycosides [forsythoside B, alyssonoside and verbascoside] and the epoxylignan lariciresinol 4'-O-β-D-glucopyranoside were isolated and identified in the EtOH extract of the aerial parts of Lippia salviaefolia Cham. The phytochemical study herein was guided by preliminary antioxidant tests, namely, β-carotene protection and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity. The crude extracts, their active fractions and the isolated compounds were assayed against intracellular reactive oxygen species (ROS) and human embryonic kidney HEK-293 and human melanoma M14 cancer cell growth. Aromadendrin and phloretin were able to counteract elevation of ROS induced by the oxidant t-butylhydroperoxide (t-BOOH) in HEK-293 cells, whereas phloretin strongly protected HEK-293 cells from ROS damage at 1 μM. Additionally, phloretin exhibited a significant growth inhibitory effect at 20-40 μM in both HEK-293 and M14 cells and induced a concentration dependent apoptosis at 20 μM in M14 cells, suggesting a selective action towards malignant cells. Due to their equilibria, the four interconverting flavanone glycosides were studied using 1D and 2D NMR, HPLC-CD-PDA and HRMS analyses.

Generation of reactive oxygen species during apoptosis induced by DNA-damaging agents and/or histone deacetylase inhibitors

Reactive oxygen species play an important role in the process of apoptosis in many cell types. In this paper, we analyzed the role of ROS in DNA-damaging agents (actinomycin D or decitabine), which induced apoptosis of leukemia cell line CML-T1 and normal peripheral blood lymphocytes (PBL). The possibility of synergism with histone deacetylase inhibitors butyrate or SAHA is also reported. We found that in cancer cell line, ROS production significantly contributed to apoptosis triggering, while in normal lymphocytes treated by cytostatic or cytotoxic drugs, necrosis as well as apoptosis occurred and large heterogeneity of ROS production was measured. Combined treatment with histone deacetylase inhibitor did not potentiate actinomycin D action, whereas combination of decitabine and SAHA brought synergistic ROS generation and apoptotic features in CML cell line. Appropriate decrease of cell viability indicated promising therapeutic potential of this combination in CML, but side effects on normal PBL should be taken into attention.

RETRACTED: Seleno-cyclodextrin sensitises human breast cancer cells to TRAIL-induced apoptosis through DR5 induction and NF-κB suppression

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). This article has been retracted at the request of This article has been retracted at the request of the authors and the Editor-in-Chief. The authors contacted the Editors of the European Journal of Cancer regarding oversights or labelling errors introduced in Fig. 2 and Fig.7 during data processing. The authors provided the raw data, however the Editors conclude that the raw data management cannot be relied upon and the article needs to be retracted.

Do reactive oxygen species play a role in myeloid leukemias?

Reactive oxygen species (ROS) are a heterogeneous group of molecules that are generated by mature myeloid cells during innate immune responses, and are also implicated in normal intracellular signaling. Excessive production of ROS (and/or a deficiency in antioxidant pathways) can lead to oxidative stress, a state that has been observed in several hematopoietic malignancies including acute and chronic myeloid leukemias (AML and CML). Currently it is unclear what the cause of oxidative stress might be and whether oxidative stress contributes to the development, progression, or maintenance of these diseases. This article reviews the current evidence suggesting a role for ROS both in normal hematopoiesis and in myeloid leukemogenesis, and discusses the usefulness of therapeutically targeting oxidative stress in myeloid malignancy.

NAD(P)H oxidase isoform Nox2 plays a prosurvival role in human leukaemia cells

The mechanism involved in the prosurvival effect of interleukin-3 on the human acute myeloid leukaemia cell line M07e is investigated. A decrease in intracellular reactive oxygen species (ROS) content, glucose transport activity and cell survival was observed in the presence of inhibitors of plasma membrane ROS sources, such as diphenylene iodonium and apocynin, and by small interference RNA for Nox2. Moreover, IL-3 incubation stimulated the synthesis of Nox2 cytosolic sub-unit p47phox and glucose transporter Glut1. Thus, the inhibition of ROS generation by Nox inhibitors stimulated apoptosis showing that ROS production, induced by IL-3 via Nox2, protects leukaemic cells from cell death. Also incubation with receptor tyrosine kinase inhibitors, such as anti-leukaemic drugs blocking the stem cell factor receptor (c-kit), showed similar effects, hinting that IL-3 transmodulates c-kit phosphorylation. These mechanisms may play an important role in acute myeloid leukaemia treatment, representing a novel therapeutic target.