The superoxide dismutase inhibitor diethyldithiocarbamate has antagonistic effects on apoptosis by triggering both cytochrome c release and caspase inhibition

Cerium Vanadate Nanozyme with pH-Dependent Dual Enzymatic Activity for Glioblastoma Targeted Therapy and Postradiotherapy Damage Protection

Nanocatalytic therapy is an emerging technology that uses synthetic nanoscale enzyme mimics for biomedical treatment. However, in the field of neuroscience, achieving neurological protection while simultaneously killing tumor cells is a technical challenge. Herein, we synthesized a biomimic and translational cerium vanadate (CeVO4) nanozyme for glioblastoma (GBM) therapy and the repair of brain damage after GBM ionizing radiation (IR). This system exhibited pH dependence: it showed potent Superoxide dismutase (SOD) enzyme activity in a neutral environment and Peroxidase (POD) enzyme activity in an acidic environment. In GBM cells, this system acted in lysosomes, causing cellular damage and reactive oxygen species (ROS) accumulation; in neuronal cells, this nanozyme could undergo lysosomal escape and nanozyme aggregation with mitochondria, reversing the mitochondrial damage caused by IR and restoring the expression level of the antiapoptotic BCL-2 protein. Mechanistically, we believe that this distribution difference is related to the specific uptake internalization mechanism and lysosomal repair pathway in neurons, and ultimately led to the dual effect of tumor killing and nerve repair in the in vivo model. In summary, this study provides insight into the repair of brain damage after GBM radiation therapy.

SOD1 inhibition enhances sorafenib efficacy in HBV-related hepatocellular carcinoma by modulating PI3K/Akt/mTOR pathway and ROS-mediated cell death

Hepatitis B Virus (HBV) infection significantly elevates the risk of hepatocellular carcinoma (HCC), with the HBV X protein (HBx) playing a crucial role in cancer progression. Sorafenib, the primary therapy for advanced HCC, shows limited effectiveness in HBV-infected patients due to HBx-related resistance. Numerous studies have explored combination therapies to overcome this resistance. Sodium diethyldithiocarbamate (DDC), known for its anticancer effects and its inhibition of superoxide dismutase 1 (SOD1), is hypothesized to counteract sorafenib (SF) resistance in HBV-positive HCCs. Our research demonstrates that combining DDC with SF significantly reduces HBx and SOD1 expressions in HBV-positive HCC cells and human tissues. This combination therapy disrupts the PI3K/Akt/mTOR signalling pathway and promotes apoptosis by increasing reactive oxygen species (ROS) levels. These cellular changes lead to reduced tumour viability and enhanced sensitivity to SF, as evidenced by the synergistic suppression of tumour growth in xenograft models. Additionally, DDC-mediated suppression of SOD1 further enhances SF sensitivity in HBV-positive HCC cells and xenografted animals, thereby inhibiting cancer progression more effectively. These findings suggest that the DDC-SF combination could serve as a promising strategy for overcoming SF resistance in HBV-related HCC, potentially optimizing therapy outcomes.

A Redox Modulatory SOD Mimetic Nanozyme Prevents the Formation of Cytotoxic Peroxynitrite and Improves Nitric Oxide Bioavailability in Human Endothelial Cells

The endothelium-derived signalling molecule nitric oxide (NO) in addition to controlling multifarious servo-regulatory functions, suppresses key processes in vascular lesion formation and prevents atherogenesis and other vascular abnormalities. The conversion of NO into cytotoxic and powerful oxidant peroxynitrite (ONOO- ) in a superoxide (O2 .- )-rich environment has emerged as a major reason for reduced NO levels in vascular walls, leading to endothelial dysfunction and cardiovascular complications. So, designing superoxide dismutase (SOD) mimetics that can selectively catalyze the dismutation of O2 .- in the presence of NO, considering their rapid reaction is challenging and is of therapeutic relevance. Herein, the authors report that SOD mimetic cerium vanadate (CeVO4 ) nanozymes effectively regulate the bioavailability of both NO and O2 .- , the two vital constitutive molecules of vascular endothelium, even in the absence of cellular SOD enzyme. The nanozymes optimally modulate the O2 .- level in endothelial cells under oxidative stress conditions and improve endogenously generated NO levels by preventing the formation of ONOO- . Furthermore, nanoparticles exhibit size- and morphology-dependent uptake into the cells and internalize via the clathrin-mediated endocytosis pathway. Intravenous administration of CeVO4 nanoparticles in mice caused no definite organ toxicity and unaltered haematological and biochemical parameters, indicating their biosafety and potential use in biological applications.

Disulfiram Oxy-Derivatives Suppress Protein Retrotranslocation across the ER Membrane to the Cytosol and Initiate Paraptosis-like Cell Death

Disulfiram (DSF) and its derivatives were here investigated as antineoplastic agents, and their important feature is the ability to influence the UPS. We have recently shown that hydroxocobalamin catalyzes the aerobic oxidation of diethyldithiocarbamate to form disulfiram and its oxy-derivatives (DSFoxy; i.e., sulfones and sulfoxides), which induce cytoplasm vacuolization and paraptosis-like cancer cell death. We used LC-MS/MS and bioinformatics analysis to determine the key points in these processes. DSFoxy was found to induce an increase in the number of ubiquitinated proteins, including oxidized ones, and a decrease in the monomeric ubiquitin. Enhanced ubiquitination was revealed for proteins involved in the response to exogenous stress, regulation of apoptosis, autophagy, DNA damage/repair, transcription and translation, folding and ubiquitination, retrograde transport, the MAPK cascade, and some other functions. The results obtained indicate that DSF oxy-derivatives enhance the oxidation and ubiquitination of many proteins regulating proteostasis (including E3 ligases and deubiquitinases), which leads to inhibition of protein retrotranslocation across the ER membrane into the cytosol and accumulation of misfolded proteins in the ER followed by ER swelling and initiates paraptosis-like cell death. Our results provide new insight into the role of protein ubiquitination/deubiquitination in regulating protein retrotranslocation across the ER membrane into the cytosol and paraptosis-like cell death.

Disulfiram oxy-derivatives induce entosis or paraptosis-like death in breast cancer MCF-7 cells depending on the duration of treatment

BACKGROUND

Dithiocarbamates and derivatives (including disulfiram, DSF) are currently investigated as antineoplastic agents. We have revealed earlier the ability of hydroxocobalamin (vitamin В_12b) combined with diethyldithiocarbamate (DDC) to catalyze the formation of highly cytotoxic oxidized derivatives of DSF (DSFoxy, sulfones and sulfoxides).

METHODS

Electron and fluorescent confocal microscopy, molecular biology and conventional biochemical techniques were used to study the morphological and functional responses of MCF-7 human breast cancer cells to treatment with DDC and B_12b alone or in combination.

RESULTS

DDC induces unfolded protein response in MCF-7 cells. The combined use of DDC and B_12b causes MCF-7 cell death. Electron microscopy revealed the separation of ER and nuclear membranes, leading to the formation of both cytoplasmic and perinuclear vacuoles, with many fibers inside. The process of vacuolization coincided with the appearance of ER stress markers, a marked damage to mitochondria, a significant inhibition of 20S proteasome, and actin depolimerization at later stages. Specific inhibitors of apoptosis, necroptosis, autophagy, and ferroptosis did not prevent cell death. A short- time (6-h) exposure to DSFoxy caused a significant increase in the number of entotic cells.

CONCLUSIONS

These observations indicate that MCF-7 cells treated with a mixture of DDC and B_12b die by the mechanism of paraptosis. A short- time exposure to DSFoxy caused, along with paraptosis, a significant activation of the entosis and its final stage, lysosomal cell death.

GENERAL SIGNIFICANCE

The results obtained open up opportunities for the development of new approaches to induce non-apoptotic death of cancer cells by dithiocarbamates.

Insights of antiparasitic activity of sodium diethyldithiocarbamate against different strains of Trypanosoma cruzi

Chagas disease is caused by Trypanosoma cruzi and affects thousands of people. Drugs currently used in therapy are toxic and have therapeutic limitations. In addition, the genetic diversity of T. cruzi represents an important variable and challenge in treatment. Sodium diethyldithiocarbamate (DETC) is a compound with pharmacological versatility acting as metal chelators and ROS generation. Thus, the objective was to characterize the antiparasitic action of DETC against different strains and forms of T. cruzi and their mechanism. The different strains of T. cruzi were grown in LIT medium. To evaluate the antiparasitic activity of DETC, epimastigote and trypomastigote forms of T. cruzi were used by resazurin reduction methods and by counting. Different response patterns were obtained between the strains and an IC₅₀ of DETC ranging from 9.44 ± 3,181 to 60.49 ± 7.62 µM. Cell cytotoxicity against 3T3 and RAW cell lines and evaluated by MTT, demonstrated that DETC in high concentration (2222.00 µM) presents low toxicity. Yet, DETC causes mitochondrial damage in T. cruzi, as well as disruption in parasite membrane. DETC has antiparasitic activity against different genotypes and forms of T. cruzi, therefore, representing a promising molecule as a drug for the treatment of Chagas disease.

A Spatiotemporal Characterisation of Redox Molecules in Planarians, with a Focus on the Role of Glutathione during Regeneration

A strict coordination between pro- and antioxidative molecules is needed for normal animal physiology, although their exact function and dynamics during regeneration and development remains largely unknown. Via in vivo imaging, we were able to locate and discriminate between reactive oxygen species (ROS) in real-time during different physiological stages of the highly regenerative planarian Schmidtea mediterranea. All ROS signals were strong enough to overcome the detected autofluorescence. Combined with an in situ characterisation and quantification of the transcription of several antioxidant genes, our data showed that the planarian gut and epidermis have a well-equipped redox system. Pharmacological inhibition or RNA interference of either side of the redox balance resulted in alterations in the regeneration process, characterised by decreased blastema sizes and delayed neurodevelopment, thereby affecting tails more than heads. Focusing on glutathione, a central component in the redox balance, we found that it is highly present in planarians and that a significant reduction in glutathione content led to regenerative failure with tissue lesions, characterised by underlying stem cell alterations. This exploratory study indicates that ROS and antioxidants are tightly intertwined and should be studied as a whole to fully comprehend the function of the redox balance in animal physiology.

Manoalide Shows Mutual Interaction between Cellular and Mitochondrial Reactive Species with Apoptosis in Oral Cancer Cells

We previously found that marine sponge-derived manoalide induced antiproliferation and apoptosis of oral cancer cells as well as reactive species generations probed by dichloro-dihydrofluorescein diacetate (DCFH-DA) and MitoSOX Red. However, the sources of cellular and mitochondrial redox stresses and the mutual interacting effects between these redox stresses and apoptosis remain unclear. To address this issue, we examined a panel of reactive species and used the inhibitors of cellular reactive species (N-acetylcysteine (NAC)), mitochondrial reactive species (MitoTEMPO), and apoptosis (Z-VAD-FMK; ZVAD) to explore their interactions in manoalide-treated oral cancer Ca9-22 and CAL 27 cells. Hydroxyl (˙OH), nitrogen dioxide (NO₂˙), nitric oxide (˙NO), carbonate radical-anion (CO₃ ^˙-), peroxynitrite (ONOO^-), and superoxide (O₂ ^˙-) were increased in oral cancer cells following manoalide treatments in terms of fluorescence staining and flow cytometry. Cellular reactive species (˙OH, NO₂ ^·, ˙NO, CO₃ ^˙-, and ONOO^-) as well as cellular and mitochondrial reactive species (O₂ ^˙-) were induced in oral cancer cells following manoalide treatment for 6 h. NAC, MitoTEMPO, and ZVAD inhibit manoalide-induced apoptosis in terms of annexin V and pancaspase activity assays. Moreover, NAC inhibits mitochondrial reactive species and MitoTEMPO inhibits cellular reactive species, suggesting that cellular and mitochondrial reactive species can crosstalk to regulate each other. ZVAD shows suppressing effects on the generation of both cellular and mitochondrial reactive species. In conclusion, manoalide induces reciprocally activation between cellular and mitochondrial reactive species and apoptosis in oral cancer cells.

Potential therapeutic targets shared between leishmaniasis and cancer

The association of leishmaniasis and malignancies in human and animal models has been highlighted in recent years. The misdiagnosis of coexistence of leishmaniasis and cancer and the use of common drugs in the treatment of such diseases prompt us to further survey the molecular biology of Leishmania parasites and cancer cells. The information regarding common expressed proteins, as possible therapeutic targets, in Leishmania parasites and cancer cells is scarce. Therefore, the current study reviews proteins, and investigates the regulation and functions of several key proteins in Leishmania parasites and cancer cells. The up- and down-regulations of such proteins were mostly related to survival, development, pathogenicity, metabolic pathways and vital signalling in Leishmania parasites and cancer cells. The presence of common expressed proteins in Leishmania parasites and cancer cells reveals valuable information regarding the possible shared mechanisms of pathogenicity and opportunities for therapeutic targeting in leishmaniasis and cancers in the future.

A Cerium Vanadate Nanozyme with Specific Superoxide Dismutase Activity Regulates Mitochondrial Function and ATP Synthesis in Neuronal Cells

Nanoparticles that functionally mimic the activity of metal-containing enzymes (metallo-nanozymes) are of therapeutic importance for treating various diseases. However, it is still not clear whether such nanozymes can completely substitute the function of natural enzymes in living cells. In this work, we show for the first time that a cerium vanadate (CeVO₄ ) nanozyme can substitute the function of superoxide dismutase 1 and 2 (SOD1 and SOD2) in the neuronal cells even when the natural enzyme is down-regulated by specific gene silencing. The nanozyme prevents the mitochondrial damage in SOD1- and SOD2-depleted cells by regulating the superoxide levels and restores the physiological levels of the anti-apoptotic Bcl-2 family proteins. Furthermore, the nanozyme effectively prevents the mitochondrial depolarization, leading to a significant improvement in the cellular levels of ATP under oxidative stress.

Vitamin B12b Enhances the Cytotoxicity of Diethyldithiocarbamate in a Synergistic Manner, Inducing the Paraptosis-Like Death of Human Larynx Carcinoma Cells

We have shown that hydroxycobalamin (vitamin B_12b) increases the toxicity of diethyldithiocarbamate (DDC) to tumor cells by catalyzing the formation of disulfiram (DSF) oxi-derivatives. The purpose of this study was to elucidate the mechanism of tumor cell death induced by the combination DDC + B_12b. It was found that cell death induced by DDC + B_12b differed from apoptosis, autophagy, and necrosis. During the initiation of cell death, numerous vacuoles formed from ER cisterns in the cytoplasm, and cell death was partially suppressed by the inhibitors of protein synthesis and folding, the IP3 receptor inhibitor as well as by thiols. At this time, a short-term rise in the expression of ER-stress markers BiP and PERK with a steady increase in the expression of CHOP were detected. After the vacuolization of the cytoplasm, functional disorders of mitochondria and an increase in the generation of superoxide anion in them occurred. Taken together, the results obtained indicate that DDC and B_12b used in combination exert a synergistic toxic effect on tumor cells by causing severe ER stress, extensive ER vacuolization, and inhibition of apoptosis, which ultimately leads to the induction of paraptosis-like cell death.

Neuronal Redox-Imbalance in Rett Syndrome Affects Mitochondria as Well as Cytosol, and Is Accompanied by Intensified Mitochondrial O 2 Consumption and ROS Release

Rett syndrome (RTT), an X chromosome-linked neurodevelopmental disorder affecting almost exclusively females, is associated with various mitochondrial alterations. Mitochondria are swollen, show altered respiratory rates, and their inner membrane is leaking protons. To advance the understanding of these disturbances and clarify their link to redox impairment and oxidative stress, we assessed mitochondrial respiration in defined brain regions and cardiac tissue of male wildtype (WT) and MeCP2-deficient (Mecp2-/y ) mice. Also, we quantified for the first time neuronal redox-balance with subcellular resolution in cytosol and mitochondrial matrix. Quantitative roGFP1 redox imaging revealed more oxidized conditions in the cytosol of Mecp2-/y hippocampal neurons than in WT neurons. Furthermore, cytosol and mitochondria of Mecp2-/y neurons showed exaggerated redox-responses to hypoxia and cell-endogenous reactive oxygen species (ROS) formation. Biochemical analyzes exclude disease-related increases in mitochondrial mass in Mecp2-/y hippocampus and cortex. Protein levels of complex I core constituents were slightly lower in Mecp2-/y hippocampus and cortex than in WT; those of complex V were lower in Mecp2-/y cortex. Respiratory supercomplex-formation did not differ among genotypes. Yet, supplied with the complex II substrate succinate, mitochondria of Mecp2-/y cortex and hippocampus consumed more O2 than WT. Furthermore, mitochondria from Mecp2-/y hippocampus and cortex mediated an enhanced oxidative burden. In conclusion, we further advanced the molecular understanding of mitochondrial dysfunction in RTT. Intensified mitochondrial O2 consumption, increased mitochondrial ROS generation and disturbed redox balance in mitochondria and cytosol may represent a causal chain, which provokes dysregulated proteins, oxidative tissue damage, and contributes to neuronal network dysfunction in RTT.

Calpain-dependent Beclin1 cleavage stimulates senescence-associated cell death in HT22 hippocampal cells under the oxidative stress conditions

Oxidative damage in neurons including glutamate excitotoxicity has been linked to increasing numbers of neuropathological conditions. Under these conditions, cells trigger several different cellular responses such as autophagy, apoptosis, necrosis and senescence. However, the connection between these responses is not well understood. In this study, we found that the 60-kDa BECN1 was specifically degraded to a 40-kDa fragment in hippocampal HT22 cells treated with 5 mM glutamate. Increased BECN1 cleavage was specifically associated with a decrease in cell viability under oxidative stress. Interestingly, this BECN1 cleavage was specifically inhibited by a calpain inhibitor ALLN but was not affected by other protease inhibitors. Also, the BECN1 cleavage was not detected in calpain-4-deficient cell lines. Furthermore, calpain cleaved BECN1 at a specific site between the coiled-coil domain and Bcl2 homology 3 domain, which is associated with the anti-apoptotic protein Bcl-2. Moreover, some cellular senescence markers, including β-galactosidase, p21, p27^Kip1, p53 and p16^INK4A, increased proportionally to those of BECN1 cleaved fragments. These results suggest that calpain-mediated BECN1 cleavage under oxidative conditions is specifically associated with cell death induced by cellular senescence.

The Specific Inhibition of SOD1 Selectively Promotes Apoptosis of Cancer Cells via Regulation of the ROS Signaling Network

Multiple signaling pathways including ERK, PI3K-Akt, and NF-κB, which are essential for onset and development of cancer, can be activated by intracellularly sustained high levels of H₂O₂ provided by elevated activity and expression of copper/zinc superoxide dismutase (SOD1) that catalyzes the dismutation of O₂^•− into H₂O₂. Here, tests performed by the utilization of our designed specific SOD1 inhibitor LD100 on cancer and normal cells reveal that the signaling pathways and their crosstalk to support cancer cell growth are repressed, but the signaling pathways to promote cancer cell cycle arrest and apoptosis are stimulated by specific SOD1 inhibition-mediated ROS changes. These regulated pathways constitute an ROS signaling network that determines the fate of cancer cells. This ROS signaling network is also regulated in SOD1 knockdown cells. These findings might facilitate disclosure of action mechanisms by copper-chelating anticancer agents and design of SOD1-targeting and ROS signaling pathway-interfering anticancer small molecules.

Hydroxycobalamin catalyzes the oxidation of diethyldithiocarbamate and increases its cytotoxicity independently of copper ions

It is known that some metals (Cu, Zn, Cd, Au) markedly increase the toxic effect of thiocarbamates. It was shown in the present study that hydroxycobalamin (a form of vitamin B12, HOCbl), which incorporates cobalt, significantly enhances the cytotoxicity of diethyldithiocarbamate (DDC), decreasing its IC50 value in tumor cells three to five times. The addition of HOCbl to aqueous DDC solutions accelerated the reduction of oxygen. No hydrogen peroxide accumulation was observed in DDC + HOCbl solutions; however, catalase slowed down the oxygen reduction rate. Catalase as well as the antioxidants N-acetylcysteine (NAC) and glutathione (GSH) partially inhibited the cytotoxic effect of DDC + HOCbl, whereas ascorbate, pyruvate, and tiron, a scavenger of superoxide anion, had no cytoprotective effect. The administration of HOCbl into DDC solutions (> 1 mM) resulted in the formation of a crystalline precipitate, which was inhibited in the presence of GSH. The data of UV and NMR spectroscopy and HPLC and Mass Spectrometry (LC/MS) indicated that the main products of the reaction of DDC with HOCbl are disulfiram (DSF) and its oxidized forms, sulfones and sulfoxides. The increase in the cytotoxicity of DDC combined with HOCbl occurred both in the presence of Cu2+ in culture medium and in nominally Cu-free solutions, as well as in growth medium containing the copper chelator bathocuproine disulfonate (BCS). The results indicate that HOCbl accelerates the oxidation of DDC with the formation of DSF and its oxidized forms. Presumably, the main cause of the synergistic increase in the toxic effect of DDC + HOCbl is the formation of sulfones and sulfoxides of DSF.

Effect of diethyldithiocarbamate in cyclophosphamide-induced nephrotoxicity: Immunohistochemical study of superoxide dismutase 1 in rat

OBJECTIVES:

To investigate the role of diethyldithiocarbamate (DEDTC) in cyclophosphamide (CP)-induced nephrotoxicity in Sprague–Dawley rat. DEDTC is a known chelating agent for copper and zinc. It is also used as a thiol protecting agent, as nuclear factor kappa-light-chain-enhancer of activated B-cells inhibitor and nitric oxide synthase inhibitor. It is also reported to inhibit superoxide dismutase (SOD) both in vitro and in vivo conditions. Considering this wide range of actions, current study investigated the role of DEDTC in CP-induced nephrotoxicity in experimental rat model.

MATERIALS AND METHODS:

Thirty-two male rats were randomized into four groups. Group 1, control received only saline ip; Group 2 and 4, received CP at the dose of 150 mg/kg body weight ip on the 4^th day, while Group 3 and 4, received DEDTC at the dose of 250 mg/kg alternatively (fractionated dose of 1000 mg/kg). All the experimental animals were sacrificed on the 7^th day and organs of interest were collected for biochemical, histopathological, DNA damage, and immunohistochemical assessments.

RESULTS:

DEDTC administration was found to further exacerbate the condition of CP-induced kidney damage as assessed by several biochemical and histological parameters. Further, the damage was also significantly reflected in the bladder in DEDTC-treated animals as compared to controls. SOD1 (Cu/Zn- dependent enzyme) expression was found to be decreased and this might be due to the action of DEDTC on SOD and other antioxidants.

CONCLUSION:

The present study indicates that DEDTC administration further exacerbated the CP-induced kidney damage in rat.

The rational design of specific SOD1 inhibitors via copper coordination and their application in ROS signaling research

Efficient methods for the regulation of intracellular O₂˙^- and H₂O₂ levels, without altering intracellular processes, are urgently required for the rapidly growing interest in ROS signaling, as ROS signaling has been confirmed to be involved in a series of basic cellular processes including proliferation, differentiation, growth and migration. Intracellular H₂O₂ is formed mainly via the catalytic dismutation of O₂˙^- by SODs including SOD1, SOD2 and SOD3. Thus, the intracellular levels of O₂˙^- and H₂O₂ can directly be controlled through regulating SOD1 activity. Here, based on the active site structure and catalytic mechanism of SOD1, we developed a new type of efficient and specific SOD1 inhibitors which can directly change the intracellular levels of H₂O₂ and O₂˙^-. These inhibitors inactivate intracellular SOD1 via localization into the SOD1 active site, thereby coordinating to the Cu²⁺ in the active site of SOD1, blocking the access of O₂˙^- to Cu²⁺, and breaking the Cu²⁺/Cu⁺ catalytic cycle essential for O₂˙^- dismutation. The reduced ERK1/2 phosphorylation induced by the specific SOD1 inactivation-mediated decrease of intracellular H₂O₂ levels reveals the potential of these specific SOD1 inhibitors in understanding and regulating ROS signaling. Furthermore, these specific SOD1 inhibitors also lead to selectively elevated cancer cell apoptosis, indicating that these kinds of SOD1 inhibitors might be candidates for lead compounds for cancer treatment.

Pterostilbene Decreases the Antioxidant Defenses of Aggressive Cancer Cells In Vivo: A Physiological Glucocorticoids- and Nrf2-Dependent Mechanism

AIMS

Polyphenolic phytochemicals have anticancer properties. However, in mechanistic studies, lack of correlation with the bioavailable concentrations is a critical issue. Some reports had suggested that these molecules downregulate the stress response, which may affect growth and the antioxidant protection of malignant cells. Initially, we studied this potential underlying mechanism using different human melanomas (with genetic backgrounds correlating with most melanomas), growing in nude mice as xenografts, and pterostilbene (Pter, a natural dimethoxylated analog of resveratrol).

RESULTS

Intravenous administration of Pter decreased human melanoma growth in vivo. However, Pter, at levels measured within the tumors, did not affect melanoma growth in vitro. Pter inhibited pituitary production of the adrenocorticotropin hormone (ACTH), decreased plasma levels of corticosterone, and thereby downregulated the glucocorticoid receptor- and nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-dependent antioxidant defense system in growing melanomas. Exogenous corticosterone or genetically induced Nrf2 overexpression in melanoma cells prevented the inhibition of tumor growth and decreased antioxidant defenses in these malignant cells. These effects and mechanisms were also found in mice bearing different human pancreatic cancers. Glutathione depletion (selected as an antimelanoma strategy) facilitated the complete elimination by chemotherapy of melanoma cells isolated from mice treated with Pter.

INNOVATION

Although bioavailability-related limitations may preclude direct anticancer effects in vivo, natural polyphenols may also interfere with the growth and defense of cancer cells by downregulating the pituitary gland-dependent ACTH synthesis.

CONCLUSIONS

Pter downregulates glucocorticoid production, thus decreasing the glucocorticoid receptor and Nrf2-dependent signaling/transcription and the antioxidant protection of melanoma and pancreatic cancer cells. Antioxid. Redox Signal. 24, 974-990.

Biological and physiological role of reactive oxygen species--the good, the bad and the ugly

Reactive oxygen species (ROS) are chemically reactive molecules that are naturally produced within biological systems. Research has focused extensively on revealing the multi-faceted and complex roles that ROS play in living tissues. In regard to the good side of ROS, this article explores the effects of ROS on signalling, immune response and other physiological responses. To review the potentially bad side of ROS, we explain the consequences of high concentrations of molecules that lead to the disruption of redox homeostasis, which induces oxidative stress damaging intracellular components. The ugly effects of ROS can be observed in devastating cardiac, pulmonary, neurodegenerative and other disorders. Furthermore, this article covers the regulatory enzymes that mitigate the effects of ROS. Glutathione peroxidase, superoxide dismutase and catalase are discussed in particular detail. The current understanding of ROS is incomplete, and it is imperative that future research be performed to understand the implications of ROS in various therapeutic interventions.

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.

Rescue of proinflammatory cytokine-inhibited chondrogenesis by the antiarthritic effect of melatonin in synovium mesenchymal stem cells via suppression of reactive oxygen species and matrix metalloproteinases

Cartilage repair by mesenchymal stem cells (MSCs) often occurs in diseased joints in which the inflamed microenvironment impairs chondrogenic maturation and causes neocartilage degradation. In this environment, melatonin exerts an antioxidant effect by scavenging free radicals. This study aimed to investigate the anti-inflammatory and chondroprotective effects of melatonin on human MSCs in a proinflammatory cytokine-induced arthritic environment. MSCs were induced toward chondrogenesis in the presence of interleukin-1β (IL-1β) or tumor necrosis factor α (TNF-α) with or without melatonin. Levels of intracellular reactive oxygen species (ROS), hydrogen peroxide, antioxidant enzymes, and cell viability were then assessed. Deposition of glycosaminoglycans and collagens was also determined by histological analysis. Gene expression of chondrogenic markers and matrix metalloproteinases (MMPs) was assessed by real-time polymerase chain reaction. In addition, the involvement of the melatonin receptor and superoxide dismutase (SOD) in chondrogenesis was investigated using pharmacologic inhibitors. The results showed that melatonin significantly reduced ROS accumulation and increased SOD expression. Both IL-1β and TNF-α had an inhibitory effect on the chondrogenesis of MSCs, but melatonin successfully restored the low expression of cartilage matrix and chondrogenic genes. Melatonin prevented cartilage degradation by downregulating MMPs. The addition of luzindole and SOD inhibitors abrogated the protective effect of melatonin associated with increased levels of ROS and MMPs. These results demonstrated that proinflammatory cytokines impair the chondrogenesis of MSCs, which was rescued by melatonin treatment. This chondroprotective effect was potentially correlated to decreased ROS, preserved SOD, and suppressed levels of MMPs. Thus, melatonin provides a new strategy for promoting cell-based cartilage regeneration in diseased or injured joints.

Cardioprotective effects of fish omega-3 fatty acids on doxorubicin-induced cardiotoxicity in rats

The aim of this study was to investigate the protective effects of fish omega-3 (n-3) fatty acids on doxorubicin (DOX)-induced acute cardiotoxicity. A total of 24 rats were divided into three groups: control, DOX-treated, and DOX treated with fish n-3 fatty acids. Control group received 0.4 ml/kg/day of saline intragastrically. The rats in the fish n-3 fatty acid-pretreated group were given 400 mg/kg/day fish n-3 fatty acids for 30 days by intragastric intubation. To induce acute cardiotoxicity, DOX (30 mg/kg) was injected intraperitoneally by a single dose and the rats were killed after 48 h. DOX treatment caused severe damage in heart tissues. Disorganization of myocardial muscle fibers, myofibrillar loss, and cardiotoxic myocardial fibers with cytoplasmic vacuoles were seen. Fish n-3 fatty acid-treated rats showed an improved histological appearance in the DOX-treated group. Our data indicate a significant reduction in the activity of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling in cardiomyocytes of the DOX-treated group with fish n-3 fatty acids therapy. The DOX-treated with fish n-3 fatty acids group showed a significant decrease in malondialdehyde levels, and an increase in superoxide dismutase and glutathione peroxidase activities in comparison with the DOX-treated group. This study showed that fish n-3 fatty acids may be a suitable cardioprotector against acute toxic effects of DOX.

Macrophage-stimulating protein attenuates hydrogen peroxide-induced apoptosis in human renal HK-2 cells

Macrophage-stimulating protein (MSP) and its receptor, recepteur d'origine nantais (RON), play an important role in cell proliferation and migration. We have investigated the role of MSP in hydrogen peroxide (H2O2)-induced renal tubular apoptosis. Human renal proximal tubular (HK-2) cells were incubated with H2O2 for 24h in the presence of different concentrations of MSP, and cell viability was measured by MTT assay. The protein expression of Bax, Bcl-2, caspase-3, mitogen-activated protein kinases (MAPKs), phosphatidylinositol-3-kinase (PI3K)/Akt, and nuclear factor-kappa B (NF-κB) was determined by semiquantitative immunoblotting. Apoptosis was assessed by flow cytometry analysis after HK-2 cells were stained with fluorescein isothiocyanate-conjugated annexin V protein and propidium iodide. H2O2 treatment decreased cell viability in HK-2 cells; this was counteracted by MSP pretreatment. H2O2 treatment induced an increased ratio of Bax/Bcl-2, cleaved caspase-3, and the number of condensed nuclei, which was also counteracted by MSP. Flow cytometry analysis showed H2O2-induced apoptosis, and its prevention by MSP treatment. Increased protein expression of phospho-p38 MAPK was attenuated by MSP, while phospho-extracellular signal-regulated kinase and c-Jun-N-terminal kinase were not affected. H2O2 induced NF-κB activation and IκB-α degradation, but the increased nuclear NF-κB activation was counteracted by MSP or by a p38 MAPK inhibitor. H2O2 treatment decreased expression of phospho-PI3K and phospho-Akt, which was reversed by MSP pretreatment. These findings suggest that MSP attenuates H2O2-induced apoptosis in HK-2 cells by modulating the p38 and NF-κB, as well as PI3K/Akt, signaling pathways.

The effects of sodium diethyldithiocarbamate in fibroblasts V79 cells in relation to cytotoxicity, antioxidative enzymes, glutathione, and apoptosis

Sodium diethyldithiocarbamate (DETC) is the main metabolite of disulfiram. Recently, we reported that mechanism of disulfiram cytotoxicity in V79 cells might be partially connected with thiol redox-state imbalance. Here, we examined the effect of DETC on the level of intracellular glutathione (GSH), protein oxidation (measured as PC—protein carbonyl content), lipid peroxidation (measured as TBARS—thiobarbituric acid reactive substances), antioxidant enzymatic defense, as well as on apoptosis. We used V79 Chinese hamster fibroblasts cells with and without modulated glutathione (GSH) level by N-acetyl-l-cysteine (NAC). We showed that treatment with DETC at concentrations that cause a moderate increase in thiol-state imbalance but not cell death stimulates oxidative stress measured as increased level of PC and TBARS, adaptive response of GSH-related enzymes and apoptosis. Our results show that cellular effects of DETC are partially attributable to the initial redox cellular state, since the increase of GSH level by NAC pre-treatment prevented the observed changes.

The p76(Rb) and p100(Rb) truncated forms of the Rb protein exert antagonistic roles on cell death regulation in human cell lines

Several caspase-cleaved forms of the retinoblastoma protein have been described. Here, we compared the effect of full-length Rb versus the truncated p76(Rb) and p100(Rb) proteins on cell death regulation in five human cell lines. Interestingly, we observed that p76(Rb) triggers cell death in all tested cell lines and that p100(Rb) protects two cell lines against etoposide or TNF-alpha-induced cell death, whereas full-length Rb has no apoptotic effect. These results show that truncated forms of Rb can have specific activities in the regulation of cell death. They also suggest that caspase cleavage of Rb should not be simply assimilated to a degradation process. Finally, we show that cell death induced by p76(Rb) is Bax-dependent and is diminished by Bcl-2 overexpression or by caspase inhibition and that p100(Rb) could inhibit cell death by decreasing both p53 stability and caspase activity.

Methanolic extract of onion (Allium cepa) attenuates ischemia/hypoxia-induced apoptosis in cardiomyocytes via antioxidant effect

BACKGROUND

Although there is growing awareness of the beneficial potential of onion intake to lower the risk of cardiovascular disease, there is little information about the effect of onion on ischemic heart injury, one of the most common cardiovascular diseases.

AIM OF THE STUDY

This study investigates the effect of the methanol-soluble extract of onion on ischemic injury in heart-derived H9c2 cells in vitro and in rat hearts in vivo. The underlying mechanism is also investigated.

METHODS

To evaluate the effect of onion on ischemia-induced cell death, LDH release and TUNEL-positivity were assessed in H9c2 cells, and the infarct size was measured in a myocardial infarct model. To investigate the mechanism of the cardioprotection by onion, the reactive oxygen species (ROS) level and the mitochondrial membrane potential (DeltaPsi(m)) were measured using an imaging technique; the caspase-3 activity was assayed, and Western blotting was performed to examine cytochrome c release in H9c2 cells.

RESULTS

The methanolic extract of onion had a preventive effect on ischemia/hypoxia-induced apoptotic death in H9c2 cells in vitro and in rat heart in vivo. The onion extract (0.05 g/ml) inhibited the elevation of the ROS, mitochondrial membrane depolarization, cytochrome c release and caspase-3 activation during hypoxia in H9c2 cells. In the in vivo rat myocardial infarction model, onion extract (10 g/kg) significantly reduced the infarct size, the apoptotic cell death of the heart and the plasma MDA level.

CONCLUSION

In conclusion, the results of this study suggest that the methanolic extract of onion attenuates ischemia/hypoxia-induced apoptosis in heart-derived H9c2 cells in vitro and in rat hearts in vivo, through, at least in part, an antioxidant effect.

Mechanisms of oxidative stress in porcine oocytes and the role of anti-oxidants

The mechanisms of oxidative stress in in vitro maturing porcine oocytes and the effects of anti-oxidant supplementation of the medium in ameliorating these effects were investigated in the present study. In addition to intracellular reduced glutathione (GSH) concentrations and DNA fragmentation, the present study focused on superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase activity. The anti-oxidants used were N-acetylcysteine (NAC) and its derivative NAC-amide (NACA). The results indicate that when SOD is inhibited, supplementation of the maturarion medium with 1.5 mm NAC or NACA compensates for the decrease in SOD activity by reducing the degree of DNA fragmentation (P < 0.05). When GPx is inhibited, supplementation of the maturarion medium with 1.5 mm NAC alleviates the effects of no GPx activity, as indicated by a decrease in the degree of DNA fragmentation (P < 0.05). When the maturarion medium was supplemented with 1.5 mm NACA, intracellular GSH concentrations decreased (P < 0.05) and SOD and catalase activities increased (P < 0.05) along with the degree of DNA fragmentation. These results indicate that the mechanisms of alleviating oxidative stress in porcine oocytes are very complex and supplementing maturing oocytes with anti-oxidants may enhance enzyme activities and eliminate free radicals.