Proapoptotic and redox state-related signaling of reactive oxygen species generated by transformed fibroblasts

2-Methoxy-1,4-naphthoquinone regulated molecular alternation of Fusarium proliferatum revealed by high-dimensional biological data

Fungi Fusarium proliferatum and the toxins it produces are hazardous to agricultural plants, animals, and human health. However, there is a lack of more effective and environment-friendly natural anti-F. proliferatum agents. In the search for natural anti-fungal agents, we found that naturally originated 2-methoxy-1,4-naphthoquinone (MNQ) with a minimal inhibitory dose of 8.0 mg L^-1 possessed a potential inhibitory effect on F. proliferatum. The results of transcriptomic, proteomic, and metabolomic reveal a total of 1314 differential expression genes (DEGs, 873 up-regulated and 441 down-regulated), 259 differential expression proteins (DEPs, 104 up-regulated and 155 down-regulated), and 86 differential accumulation metabolites (DAMs, 49 up-regulated and 37 down-regulated) in MNQ-induced F. proliferatum. Further, the correlation analysis of transcriptomic, proteomic, and metabolomic indicated that these DEGs, DEPs, and DAMs were co-mapped in the pathways of glyoxylate and dicarboxylate metabolism, glycine, serine, and threonine metabolism, and pyruvate metabolism that linked to the TCA cycle. Furthermore, the key DEGs of the significantly co-mapped pathways were verified with qPCR analysis, which was related to the permeability of the cell membrane of F. proliferatum. Thus, these findings will provide fundamental scientific data on the molecular shifts of MNQ-induced F. proliferatum.

Therapeutic Potential of Reactive Oxygen Species: State of the Art and Recent Advances

In the last decade, several studies have proven that when at low concentration reactive oxygen species (ROS) show an adaptive beneficial effect and posited the idea that they can be utilized as inexpensive and convenient inducers of tissue regeneration. On the other hand, the recent discovery that cancer cells are more sensitive to oxidative damage paved the way for their use in the selective killing of tumor cells, and sensors to monitor ROS production during cancer treatment are under extensive investigation. Nevertheless, although ROS-activated signaling pathways are well established, less is known about the mechanisms underlying the switch from an anabolic to a cytotoxic response. Furthermore, a high variability in biological response is observed between different modalities of administration, cell types, donor ages, eventual concomitant diseases, and external microenvironment. On the other hand, available preclinical studies are scarce, whereas the quest for the most suitable systems for in vivo delivery is still elusive. Furthermore, new strategies to control the temporal pattern of ROS release need to be developed, if considering their tumorigenic potential. This review initially discusses ROS mechanisms of action and their potential application in stem cell biology, tissue engineering, and cancer therapy. It then outlines the state of art of ROS-based drugs and identifies challenges faced in translating ROS research into clinical practice.

Fluorescent Diagnostic Probes in Neurodegenerative Diseases

Neurodegenerative diseases are debilitating disorders that feature progressive and selective loss of function or structure of anatomically or physiologically associated neuronal systems. Both chronic and acute neurodegenerative diseases are associated with high morbidity and mortality along with the death of neurons in different areas of the brain; moreover, there are few or no effective curative therapy options for treating these disorders. There is an urgent need to diagnose neurodegenerative disease as early as possible, and to distinguish between different disorders with overlapping symptoms that will help to decide the best clinical treatment. Recently, in neurodegenerative disease research, fluorescent-probe-mediated biomarker visualization techniques have been gaining increasing attention for the early diagnosis of neurodegenerative diseases. A survey of fluorescent probes for sensing and imaging biomarkers of neurodegenerative diseases is provided. These imaging probes are categorized based on the different potential biomarkers of various neurodegenerative diseases, and their advantages and disadvantages are discussed. Guides to develop new sensing strategies, recognition mechanisms, as well as the ideal features to further improve neurodegenerative disease fluorescence imaging are also explored.

Anticancer activity of functional polysuccinates with N-acetyl-cysteine in side chains

The synthesis and characteristics of functional polyesters with a potential anticancer activity have been described, followed by a post-modification process of biologically active polymers. First, biodegradable functional polysuccinates possessing pendant allyl groups, that are susceptible to thiol-ene reaction, were obtained by polyaddition of succinic anhydride and allyl glycidyl ether. The functionality of such polyesters was regulated by replacing a part of unsaturated glycidyl ether with saturated ones. Polymers containing 20-100% mers with allyl groups were reacted with N-acetyl-cysteine (NAC). The use of simple click reaction allowed obtaining polyesters containing different amounts of N-acetyl-cysteine in side chains. The thus obtained polymers with a molecular weight of several thousand are characterized by solubility in methanol as opposed to their initial precursors. Modified polyesters show no toxicity to normal human keratinocytes (HaCaT) cells, similar to the NAC in normal human fibroblasts (NHDF), whereas the anticancer activities were observed against squamous carcinoma (SCC-25), and melanoma (Me45) cells. A standard colorimetric assay (MTS), to assessing cells viability and cytotoxicity of tested compounds, was performed against NHDF for NAC, HaCaT, SCC-25, and Me45 cells, within 24-144 h long-term expositions. Neither contact with NAC alone, and tested materials, nor long incubation decreased normal cell viability or induced inflammation. That reassumed the potential of anticancer activities of tested materials, with the tendency to visible selectivity against cancer cell lines in vitro, confirmed with live microscopic imaging against the Me45 cell line.

Polarizing Graphene Quantum Dots toward Long-Acting Intracellular Reactive Oxygen Species Evaluation and Tumor Detection

The evaluation of intracellular reactive oxygen species (ROS) would greatly deepen the understanding of cell metabolism/proliferation and tumor detection. However, current long-acting level tracking techniques for intracellular ROS remain unsuited to practical applications. To solve this problem, we synthesized cyclotriphosphazene-doped graphene quantum dots (C-GQDs) whose quantum yield is highly sensitive to ROS (increased by 400% from 0.12 to 0.63). Electron cloud polarization of oxidized cyclotriphosphazene rings in C-GQDs is confirmed to account for this novel optical property by density functional theory calculations and experimental results. In combination with excellent biological stability, C-GQDs achieve a long-acting evaluation of intracellular ROS level (more than 72 h) with an accuracy of 98.3%. In addition, recognition rates exceeding 90% are demonstrated to be feasible for eight kinds of tumor cell lines cultured with C-GQDs, which can also be expanded to in vivo detection. C-GQDs also show a high recognition rate (82.33%) and sensitivity (79.65%) for tumor cells in blood samples.

Anti-cancer agents and reactive oxygen species modulators that target cancer cell metabolism

Traditionally the perspective on reactive oxygen species (ROS) has centered on the role they play as carcinogenic or cancer-causing radicals. Over the years, characterization and functional studies have revealed the complexity of ROS as signaling molecules that regulate various physiological cellular responses or whose levels are altered in various diseases. Cancer cells often maintain high basal level of ROS and are vulnerable to any further increase in ROS levels beyond a certain protective threshold. Consequently, ROS-modulation has emerged as an anticancer strategy with synthesis of various ROS-inducing or responsive agents that target cancer cells. Of note, an increased carbohydrate uptake and/or induction of death receptors of cancer cells was exploited to develop glycoconjugates that potentially induce cellular stress, ROS and apoptosis. This mini review highlights the development of compounds that target cancer cells by taking advantage of redox or metabolic alteration in cancer cells.

Synergistic Combination for Chemoprevention of Hepatocellular Carcinoma: An In Silico and In Vitro Approach

Combination therapy is one of the best methods to manage the fatality rate in hepatocellular carcinoma (HCC). This study aimed to formulate a synergistic combination of synthetic and herbal compounds for the treatment of HCC as well as to elucidate a possible signalling mechanism. MTT and enzymatic assay were performed to determine the synergistic effect of drug combination (sorafenib, vitamin K1 and trans-chalcone) on HepG2 cell lines after intoxication with H₂ O₂ . Protein-protein interaction and docking studies were performed using Pathwaylinker2.0 and Schrödinger's software application to find out the mechanism of action and major targets for drug combination. The overall in vitro result showed that combination of trans-chalcone, vitamin K1 and sorafenib (10, 5 and 5 μM concentration, respectively) enhanced the resistance against oxidative stress generated by H₂ O₂ . The interaction studies helped in identification of few targets for docking of ligands (trans-chalcone, vitamin K1 and sorafenib). The study reports the synergistic effects of the formulation that can protect the cells from oxidative stress and restore normal levels of cellular enzymes in HepG2 cell line. We were able to determine the mechanism of action of herbal and synthetic formulation through in silico studies. Finally, docking studies confirmed potential targets for inhibition of hepatocarcinogenesis.

Cytotoxic responses to 405nm light exposure in mammalian and bacterial cells: Involvement of reactive oxygen species

Light at wavelength 405 nm is an effective bactericide. Previous studies showed that exposing mammalian cells to 405 nm light at 36 J/cm(2) (a bactericidal dose) had no significant effect on normal cell function, although at higher doses (54 J/cm(2)), mammalian cell death became evident. This research demonstrates that mammalian and bacterial cell toxicity induced by 405 nm light exposure is accompanied by reactive oxygen species production, as detected by generation of fluorescence from 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate. As indicators of the resulting oxidative stress in mammalian cells, a decrease in intracellular reduced glutathione content and a corresponding increase in the efflux of oxidised glutathione were observed from 405 nm light treated cells. The mammalian cells were significantly protected from dying at 54 J/cm(2) in the presence of catalase, which detoxifies H2O2. Bacterial cells were significantly protected by sodium pyruvate (H2O2 scavenger) and by a combination of free radical scavengers (sodium pyruvate, dimethyl thiourea (OH scavenger) and catalase) at 162 and 324 J/cm(2). Results therefore suggested that the cytotoxic mechanism of 405 nm light in mammalian cells and bacteria could be oxidative stress involving predominantly H2O2 generation, with other ROS contributing to the damage.

Increasing the endogenous NO level causes catalase inactivation and reactivation of intercellular apoptosis signaling specifically in tumor cells

Tumor cells generate extracellular superoxide anions and are protected against intercellular apoptosis-inducing HOCl- and NO/peroxynitrite signaling through the expression of membrane-associated catalase. This enzyme decomposes H₂O₂ and thus prevents HOCl synthesis. It efficiently interferes with NO/peroxynitrite signaling through oxidation of NO and decomposition of peroxynitrite. The regulatory potential of catalase at the crosspoint of ROS and RNS chemical biology, as well as its high local concentration on the outside of the cell membrane of tumor cells, establish tight control of intercellular signaling and thus prevent tumor cell apoptosis. Therefore, inhibition of catalase or its inactivation by singlet oxygen reactivate intercellular apoptosis-inducing signaling. Nitric oxide and peroxynitrite are connected with catalase in multiple and meaningful ways, as (i) NO can be oxidated by compound I of catalase, (ii) NO can reversibly inhibit catalase, (iii) peroxynitrite can be decomposed by catalase and (iv) the interaction between peroxynitrite and H₂O₂ leads to the generation of singlet oxygen that inactivates catalase. Therefore, modulation of the concentration of free NO through addition of arginine, inhibition of arginase, induction of NOS expression or inhibition of NO dioxygenase triggers an autoamplificatory biochemical cascade that is based on initial formation of singlet oxygen, amplification of superoxide anion/H₂O₂ and NO generation through singlet oxygen dependent stimulation of the FAS receptor and caspase-8. Finally, singlet oxygen is generated at sufficiently high concentration to inactivate protective catalase and to reactivate intercellular apoptosis-inducing ROS signaling. This regulatory network allows to establish several pathways for synergistic interactions, like the combination of modulators of NO metabolism with enhancers of superoxide anion generation, modulators of NO metabolism that act at different targets and between modulators of NO metabolism and direct catalase inhibitors. The latter aspect is explicitely studied for the interaction between catalase inhibiting acetylsalicylic acid and an NO donor. It is also shown that hybrid molecules like NO-aspirin utilize this synergistic potential. Our data open novel approaches for rational tumor therapy based on specific ROS signaling and its control in tumor cells.

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Membrane-associated catalase protects tumor cells against ROS/RNS signaling.

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NO can be oxidated by catalase, but can also reversibly inhibit the enzyme.

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ONOO⁻ is decomposed by catalase but also drives its inactivation through singlet oxygen.

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Modulation of the NO level triggers singlet oxygen generation and catalase inactivation.

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This signaling network allows to establish synergistic antitumor effects.

17β-Estradiol Stimulates Generation of Reactive Species Oxygen and Nitric Oxide in Ovarian Adenocarcinoma Cells (OVCAR 3)

BACKGROUND

Experimental and epidemiological evidence supports a role for steroid hormones in the pathogenesis of ovarian cancer. Among steroid hormones, 17β-estradiol (E2) has the most potent effect on proliferation, apoptosis and metastasis.

OBJECTIVES

In the present study, we investigated the effect of E2 on production of ROS and NO in ovarian cancer cells.

MATERIALS AND METHODS

Ovarian adenocarcinoma cell line (OVCAR-3) was cultured and treated with various concentrations of E2, antioxidants (N-acetyle cysteine and Ebselen) and ICI182780 as an estrogen receptor antagonist. MTT test was performed to evaluate cell viability. NO and ROS levels were measured by Griess and DCFH-DA methods, respectively.

RESULTS

ROS levels as well as NO levels were increased in OVCAR-3 cells treated with E2. The increase in ROS production was in parallel with increased cell viability which indicates that estrogen-induced ROS can participate in cancer progression. ICI182780 abolished E2-induced ROS production. Progesterone was also effective in reducing ROS and NO generation.

CONCLUSIONS

NO and ROS are important molecules in signaling networks in cell. These molecules can be used as therapeutic targets for prevention and treatment of ovary cancer and other estrogen-induced malignancies.

Revealing mechanisms of selective, concentration-dependent potentials of 4-hydroxy-2-nonenal to induce apoptosis in cancer cells through inactivation of membrane-associated catalase

Tumor cells generate extracellular superoxide anions and are protected against superoxide anion-mediated intercellular apoptosis-inducing signaling by the expression of membrane-associated catalase. 4-Hydroxy-2-nonenal (4-HNE), a versatile second messenger generated during lipid peroxidation, has been shown to induce apoptosis selectively in malignant cells. The findings described in this paper reveal the strong, concentration-dependent potential of 4-HNE to specifically inactivate extracellular catalase of tumor cells both indirectly and directly and to consequently trigger apoptosis in malignant cells through superoxide anion-mediated intercellular apoptosis-inducing signaling. Namely, 4-HNE caused apoptosis selectively in NOX1-expressing tumor cells through inactivation of their membrane-associated catalase, thus reactivating subsequent intercellular signaling through the NO/peroxynitrite and HOCl pathways, followed by the mitochondrial pathway of apoptosis. Concentrations of 4-HNE of 1.2 µM and higher directly inactivated membrane-associated catalase of tumor cells, whereas at lower concentrations, 4-HNE triggered a complex amplificatory pathway based on initial singlet oxygen formation through H2O2 and peroxynitrite interaction. Singlet-oxygen-dependent activation of the FAS receptor and caspase-8 increased superoxide anion generation by NOX1 and amplification of singlet oxygen generation, which allowed singlet-oxygen-dependent inactivation of catalase. 4-HNE and singlet oxygen cooperate in complex autoamplificatory loops during this process. The finding of these novel anticancer pathways may be useful for understanding the role of 4-HNE in the control of malignant cells and for the optimization of ROS-dependent therapeutic approaches including antioxidant treatments.

Comparative anti-proliferative activity of some new 2-(arylazo)phenolate-palladium (II) complexes and cisplatin against some human cancer cell lines

In this study, we report the synthesis of four 2-(arylazo)phenol-Pd(II) complexes and their anti-proliferative property against the human lung cancer (A549), cervical cancer (HeLa), and ovarian teratocarcinoma (PA-1) cell lines with cisplatin as the gold standard. One of the complexes, [Pd(L(2))2], induced robust apoptosis in all the chosen cells, as revealed by annexin-V-positive/propidium iodide dual staining, increased sub-G1 cell cycle population, and significant morphological changes in the treated cells. The Pd complex inflicted mitochondrial dysfunction leading to mitochondrial membrane potential loss, reactive oxygen species generation and release of cytosolic cytochrome c that activated caspase-9 and caspase-3 proteins which finally caused programmed cell death.

Highly reactive oxygen species: detection, formation, and possible functions

The so-called reactive oxygen species (ROS) are defined as oxygen-containing species that are more reactive than O(2) itself, which include hydrogen peroxide and superoxide. Although these are quite stable, they may be converted in the presence of transition metal ions, such as Fe(II), to the highly reactive oxygen species (hROS). hROS may exist as free hydroxyl radicals (HO·), as bound ("crypto") radicals or as Fe(IV)-oxo (ferryl) species and the somewhat less reactive, non-radical species, singlet oxygen. This review outlines the processes by which hROS may be formed, their damaging potential, and the evidence that they might have signaling functions. Since our understanding of the formation and actions of hROS depends on reliable procedures for their detection, particular attention is given to procedures for hROS detection and quantitation and their applicability to in vivo studies.

NF-κB suppresses ROS levels in BCR-ABL(+) cells to prevent activation of JNK and cell death

Elevated levels of reactive oxygen species are found in most oncogenically transformed cells and are proposed to promote cellular transformation through mechanisms such as inhibition of phosphatases. BCR-ABL, the oncoprotein associated with the majority of chronic myelogenous leukemias, induces accumulation of intracellular ROS causing enhanced signaling downstream of PI3K. Previously we have shown that the transcription factor NF-κB is activated by BCR-ABL expression and is required for BCR-ABL-mediated cellular transformation. Inhibition of IKKβ and NF-κB leads to cell death through an unknown mechanism. Here, we analyze the potential involvement of NF-κB in moderating BCR-ABL-induced ROS levels to protect from death in response to cell stress. The data confirm that BCR-ABL promotes ROS levels and demonstrate that NF-κB prevents excessive ROS levels. Inhibition of NF-κB leads to an increase in ROS levels and to cell death controlled through ROS-induced JNK activity. The data demonstrate that one function for NF-κB in oncogenesis is the suppression of oncoprotein-induced ROS levels and that inhibition of NF-κB in some cancers, including CML, will increase ROS levels and promote cell death.

D-4F, an apoA-I mimetic peptide, inhibits proliferation and tumorigenicity of epithelial ovarian cancer cells by upregulating the antioxidant enzyme MnSOD

We recently reported that apoA-I and apoA-I mimetic peptides prevent the development of flank tumors in immunocompetent C57BL/6J mice. To delineate the mechanism(s) of action of apoA-I mimetic peptides in tumor development, we examined the effect of D-4F (an apoA-I mimetic peptide) on the antioxidant status and on the gene expression and function of antioxidant enzymes in ID8 cells (a mouse epithelial ovarian cancer cell line) and in a mouse model. We demonstrate that D-4F treatment significantly reduces the viability and proliferation of ID8 cells, with a concomitant improvement of the antioxidant status of ID8 cells as measured by lipid peroxidation, protein carbonyl, superoxide anion, and hydrogen peroxide levels. D-4F treatment induces MnSOD (but not CuZnSOD) mRNA, protein, and activity. Inhibition of MnSOD in ID8 cells using shRNA vectors abrogates the inhibitory effects of D-4F on ID8 cell viability and proliferation. Moreover, tumor development from ID8 cells carrying shRNA for MnSOD were unaffected by D-4F treatment. Our results suggest that the inhibitory effects of D-4F on ID8 cell proliferation and tumor development are mediated, at least in part, by the induced expression and activity of MnSOD.

Intracellular GSH depletion triggered mitochondrial Bax translocation to accomplish resveratrol-induced apoptosis in the U937 cell line

We have previously demonstrated that resveratrol (Resv)-induced cellular apoptosis occurs after formation of reactive oxygen species (ROS) but the role of GSH has not been well defined. Our experimental data enumerated that Resv treatment (50 μm) induced apoptosis in human leukemic monocyte lymphoma cells, which was preceded by cellular GSH efflux. High concentration of extracellular thiol (GSH, N-acetyl cysteine) and two specific inhibitors of carrier-mediated GSH extrusion, methionine or cystathionine, prevented the process of oxidative burst and cell death. This proved that GSH efflux could be a major molecular switch to modulate Resv-induced ROS generation. Spectrofluorometric data depicted that after 6 h of Resv treatment, ROS generation was evident. Pretreatment of cells with intracellular ROS scavenger (polyethylene glycol-superoxide dismutase and polyethylene glycol-catalase) efficiently reduced ROS generation but failed to prevent intracellular GSH depletion. Thus, it suggested that intracellular GSH depletion was independent of ROS production but dependent on GSH extrusion. Furthermore, to bridge the link between GSH efflux and ROS generation, we carried out confocal microscopy of the localization of Bax protein. Microscopic analysis and small interfering RNA treatment emphasized that cellular GSH efflux triggered Bax translocation to mitochondria, which resulted in the loss of mitochondrial membrane potential, ROS generation, and caspase 3 activation and thus triggered apoptosis.

Heat stress upregulates chaperone heat shock protein 70 and antioxidant manganese superoxide dismutase through reactive oxygen species (ROS), p38MAPK, and Akt

Chinese hamster lung fibroblasts V79 cells were treated with heat stress for 4 weeks with short duration (15 min) heat shock every alternate day in culture. It was observed that Hsp 70 and the antioxidant enzyme MnSOD became overexpressed during the chronic heat stress period. Both p38 MAPK and Akt became phosphorylated by chronic heat stress exposure. Simultaneous exposure to SB203580, a potent and specific p38MAPK inhibitor drastically inhibited the phosphorylation of p38MAPK and Akt. Furthermore, exposure to SB203580 also blocked the increase in Hsp70 and MnSOD levels and the elevated SOD activity brought about by chronic heat stress. Heat shock factor 1 (HSF1) transcriptional activity and nuclear translocation of HSF1 were prominently augmented by chronic heat stress, and this amplification is markedly reduced by concomitant exposure to SB203580. Also, activations of p38MAPK and Akt and upregulations of Hsp70 and MnSOD were observed on exposure to heat shock for a single exposure of longer duration (40 min). siRNA against p38MAPK notably reduced Akt phosphorylation by single exposure to heat stress and drastically diminished the rise in Hsp70 and MnSOD levels. Similarly, siRNA against Akt also eliminated the augmentation in Hsp70 and MnSOD levels but p38MAPK levels remained unaffected. Heat stress produced reactive oxygen species (ROS) in V79 fibroblasts. N-acetyl cysteine blocked the increase in phosphorylation of p38MAPK, amplification of Hsp70, and MnSOD levels by heat stress. Therefore, we conclude that heat stress-activated p38MAPK which in turn activated Akt. Akt acted downstream of p38MAPK to increase Hsp70 and MnSOD levels.Concise summary: Thermal injury of the skin over a long period of time has been associated with development of cancerous lesions. Also, in many cancers, the cytoprotective genes Hsp70 and MnSOD have been found to be overexpressed. Therefore, we considered it important to identify the signaling elements upstream of the upregulated survival genes in heat stress. We conclude that heat stress activated p38MAPK which in turn activated Akt. Akt mediated an augmentation in Hsp70 and MnSOD levels working downstream of p38MAPK.

Quantitative differential proteome analysis in an animal model for human melanoma

In fish of the genus Xiphophorus, different grades of pigment cell lesions from nevi to melanoma can be gained by simple crossbreeding. With this model, one can easily access tissues of different malignancies from animals with highly identical genetic background. To find protein expression differences between healthy, benign and malignant tissues, we performed 2D PAGE and DIGE and found among regulated proteins antioxidant proteins that were overexpressed with increasing malignancy.

A model of interactions between radiation-induced oxidative stress, protein and DNA damage in Deinococcus radiodurans

Ionizing radiation triggers oxidative stress, which can have a variety of subtle and profound biological effects. Here we focus on mathematical modeling of potential synergistic interactions between radiation damage to DNA and oxidative stress-induced damage to proteins involved in DNA repair/replication. When sensitive sites on these proteins are attacked by radiation-induced radicals, correct repair of dangerous DNA lesions such as double strand breaks (DSBs) can be compromised. In contrast, if oxidation of important proteins is prevented by strong antioxidant defenses, DNA repair may function more efficiently. These processes probably occur to some extent even at low doses of radiation/oxidative stress, but they are easiest to investigate at high doses, where both DNA and protein damage are extensive. As an example, we use data on survival of Deinococcus radiodurans after high doses (thousands of Gy) of acute and chronic irradiation. Our model of radiogenic oxidative stress is consistent with these data and can potentially be generalized to other organisms and lower radiation doses.

Involvement of Rac in fenretinide-induced apoptosis

The synthetic retinoid N-(4-hydroxyphenyl)retinamide (4HPR) has shown potential as a chemopreventive and therapeutic agent. The ability of 4HPR to enhance production of reactive oxygen species (ROS) leading to apoptosis has been suggested as a possible mechanism underlying these effects. We explored the possibility that ROS induction by 4HPR involves the small GTPase Ras-related C3 botulinum toxin substrate (Rac), a regulatory subunit of the NADPH oxidase complex. Rac was activated in human head and neck squamous cell carcinoma (HNSCC) cells as early as 5 minutes following 4HPR exposure. Moreover, inhibition of Rac activity or silencing of its expression by RNA interference decreased ROS generation in human head and neck, lung, and cervical cancer cells and murine melanoma cells. In HNSCC UMSCC-22B cells, this decrease correlated with reduction in apoptosis induction by 4HPR. Expression of a constitutive active mutant Rac increased basal and 4HPR-induced ROS generation and poly(ADP-ribose) polymerase cleavage. In addition, the metastatic DM14 cells exhibited higher Rac activation following 4HPR treatment compared with the primary Tu167-C2 cells. Furthermore, the metastatic cancer cells tested exhibited higher ROS generation and growth inhibition due to 4HPR exposure compared with their primary cancer cell counterparts. These findings show a preferential susceptibility of metastatic cells to the proapoptotic retinoid 4HPR through Rac activation and support the use of ROS-inducing agents such as 4HPR against metastatic cancer cells.

Low dose radiation and intercellular induction of apoptosis: potential implications for the control of oncogenesis

PURPOSE

This review is focused on the potential impact of low dose radiation effects on intercellular induction of apoptosis and the underlying reactive-oxygen species (ROS)-mediated signaling pathways.

RESULTS

Transformed cells are subject to ROS-mediated apoptosis induction by non-transformed cells ('intercellular induction of apoptosis') and by ROS-mediated autocrine self-destruction. Sensitivity to intercellular induction of apoptosis and autocrine self-destruction are strictly correlated to the expression of the transformed state. Extracellular superoxide anions generated by transformed target cells drive the selectivity and sensitivity of this signaling system which is based on four different signaling pathways. Low dose irradiation of non-transformed cells enhances intercellular induction of apoptosis in transformed cells. This process is controlled by TGF-beta and seems to depend on the induction of peroxidase release. In addition, low dose radiation enhances superoxide anion generation of transformed target cells.

CONCLUSIONS

Low dose radiation-triggered enhancement of intercellular induction of apoptosis and autocrine self-destruction might represent a potential control system during carcinogenesis. It might be the underlying mechanism for the well-known inhibitory effect of low dose radiation on detectable transformation events. However, modifications of the complex intercellular ROS-based signaling system may also lead to configurations in which low dose radiation attenuates ROS-mediated apoptosis induction.

The first application of terephthalate fluorescence for highly selective detection of hydroxyl radicals in thylakoid membranes

Possibilities and limitations of the detection of hydroxyl radicals via the conversion of terephthalate (TPA) into the strongly fluorescent hydroxyterephthalate were investigated in order to adapt this method for chlorophyll-containing samples. Using model chemical sources of various reactive oxygen species, we confirmed that TPA detects hydroxyl radicals very sensitively, but is not reactive to either hydrogen peroxide or superoxide radicals. As a new result, we showed that the conversion of TPA to hydroxyterephthalate cannot be induced by singlet oxygen, which may be produced in photosynthetic systems under stress. Until now, the TPA method has not been used in photosynthesis research, so necessary adaptations to minimise the effects of chlorophyll and buffering sugars on hydroxyl radical detection were also explored and optimal conditions for using the method in thylakoid preparations are suggested. Anticipating further plant physiology applications, usefulness of the TPA method was tested in a wider range of pH than reported earlier. To demonstrate that this simple and highly specific method can be used as an alternative approach for the detection of hydroxyl radicals in plant samples, we measured these radicals in isolated thylakoid membranes exposed to 312 nm ultraviolet radiation.

Hydrogen peroxide: a metabolic by-product or a common mediator of ageing signals?

The reactive oxygen species that are generated by mitochondrial respiration, including hydrogen peroxide (H2O2), are potent inducers of oxidative damage and mediators of ageing. It is not clear, however, whether oxidative stress is the result of a genetic programme or the by-product of physiological processes. Recent findings demonstrate that a fraction of mitochondrial H2O2, produced by a specialized enzyme as a signalling molecule in the pathway of apoptosis, induces intracellular oxidative stress and accelerates ageing. We propose that genes that control H2O2 production are selected determinants of lifespan.

Ceramide attenuates hypoxic cell death via reactive oxygen species signaling

We have previously demonstrated that tumor necrosis factor alpha (TNFalpha), a cytokine known to be induced by ischemia, independently promotes preconditioning in part via ceramide generation. As reactive oxygen species (ROS) signaling is evoked by ischemic preconditioning, by TNFalpha and by ceramide we reasoned that ceramide-induced preconditioning is ROS-mediated. Fibroblastic L-cells were subjected to 8 hours simulated ischemia and were preconditioned by pretreatment with cell permeable c2 ceramide (1 microM) with or without the antioxidant N-mercaptopropionyl glycine (MPG; 1 mM). Pretreatment with ceramide reduced lactate dehydrogenase release at the end of the simulated ischemia but this cytoprotective effect was lost in the presence of MPG. Concurrent temporal ROS generation was measured using confocal microscopy on cells stained with dichlorofluorescein diacetate (DCF-DA). Ceramide increased ROS production after 30 minutes and this induction was decreased by MPG. Incubation of ceramide with cyclooxygenase-2 inhibitor, NS 398 (10 microM), or with a mitochondrial respiratory chain inhibitor, rotenone (10 microM) reduced the cytoprotective effect of ceramide in parallel with a partial diminution in ROS generation. In contrast, inhibition of other ROS-producing systems including nitric oxide synthase, xanthine oxidase, or NADPH oxidase failed to modulate ceramide-induced cytoprotection. Collectively, these data demonstrate that ceramide induces a cell survival program through ROS signaling activated, in part, via cyclooxygenase and the mitochondrial respiratory chain.

Cell proliferation, reactive oxygen and cellular glutathione

A variety of cellular activities, including metabolism, growth, and death, are regulated and modulated by the redox status of the environment. A biphasic effect has been demonstrated on cellular proliferation with reactive oxygen species (ROS)-especially hydrogen peroxide and superoxide-in which low levels (usually submicromolar concentrations) induce growth but higher concentrations (usually >10-30 micromolar) induce apoptosis or necrosis. This phenomenon has been demonstrated for primary, immortalized and transformed cell types. However, the mechanism of the proliferative response to low levels of ROS is not well understood. Much of the work examining the signal transduction by ROS, including H(2)O(2), has been performed using doses in the lethal range. Although use of higher ROS doses have allowed the identification of important signal transduction pathways, these pathways may be activated by cells only in association with ROS-induced apoptosis and necrosis, and may not utilize the same pathways activated by lower doses of ROS associated with increased cell growth. Recent data has shown that low levels of exogenous H(2)O(2) up-regulate intracellular glutathione and activate the DNA binding activity toward antioxidant response element. The modulation of the cellular redox environment, through the regulation of cellular glutathione levels, may be a part of the hormetic effect shown by ROS on cell growth.

Enhanced tumorigenesis in p53 knockout mice exposed in utero to high-dose vitamin E

The limited antioxidative capacity of the embryo and fetus may increase their risk for cancer initiation and/or promotion by reactive oxygen species (ROS)-mediated oxidative DNA damage and/or signaling. To determine if cancer can originate in utero, a high dietary dose of the antioxidant vitamin E (VE) (10% dl-alpha-tocopherol-acetate) was given to cancer-prone p53 knockout mice throughout pregnancy. Although reducing fetal death (P < 0.05), in utero exposure to VE enhanced postnatal tumorigenesis in both +/- (P < 0.04) and -/- (P < 0.0008) p53-deficient offspring. VE did not alter maternal weights, offspring p53 genotypic distribution or tumor spectrum. Constitutive embryonic DNA oxidation in untreated -/- p53 embryos [gestational day (GD) 13] was higher than in +/- and +/+ p53 littermates (P < 0.05). VE reduced DNA oxidation in -/- p53 embryos (P < 0.05) without affecting +/- and +/+ p53 littermates. VE had contrasting, tissue-dependent effects on fetal (GD 19) DNA oxidation, with reductions in -/- and +/- p53-deficient fetal brains (P < 0.01), increases in skin (P < 0.05) and no effect in liver and thymus. The 250-fold increase in dietary VE levels produced only 1.6-6.3-fold, tissue-dependent increases in tissue concentrations. The greatest increase, in fetal skin, correlated with increased DNA oxidation in that tissue in -/- and +/- p53-deficient fetuses and enhanced tumorigenesis in these genotypes. These results show that some cancers may originate in utero and the risk can be enhanced by embryonic and fetal exposure to high dietary levels of VE. The elevated DNA oxidation in some tissues of untreated -/- p53 offspring suggests that ROS may contribute to their higher baseline tumor incidence. The limited and tissue-dependent disposition of VE indicates substantial conceptal regulation. The similarly selective and contrasting effects of VE on DNA oxidation may contribute to its controversial protective efficacy and suggest that its effects on tumorigenesis are cell-specific, possibly in high doses involving a pro-oxidative mechanism.

Tumor suppressive activity of a variant isoform of manganese superoxide dismutase released by a human liposarcoma cell line

A cell line derived from a pleiomorphic liposarcoma, named LSA, was previously reported to secrete (a) factor(s) exhibiting oncotoxic properties. The present article describes the isolation, purification and sequence analysis of a protein released by LSA cells into conditioned culture medium. This protein proved to be a variant isoform of manganese superoxide dismutase (MnSOD), hence its designation as LSA-type-MnSOD. This LSA-type-SOD differed from conventional SODs in its secretion by producer cells, contrasting with the normal localization of SODs in the mitochondrial matrix. Interestingly, during the protein purification process, LSA-type-SOD cosegregated with a cytotoxic activity directed against a number of tumor cell lines, as determined under in vitro conditions. This cytopathic effect was most likely due to LSA-type-SOD, since it could be fully reproduced using recombinant SOD that was expressed from cDNA clones isolated from LSA cells mRNA preparations and henceforth designated L-rSOD. In addition to its manifestation in cell lines kept in tissue culture, the oncotoxicity of LSA-type-SOD was further reflected in a remarkable capacity of this protein for suppression of mammary tumors in Balb-C-FR(III) mice. Animals subcutaneously injected with L-rSOD in the tumor area showed a complete disruption of established mammary carcinomas, as monitored by nuclear magnetic resonance (NMR) scanning. Moreover, metastatic spreading, which was readily detected in the control group, was suppressed in the treated animals. Altogether these data suggest that LSA-type-SOD interferes with survival and spreading of neoplastically transformed cells and deserves to be future validated as a therapeutic agent against cancer, either alone or in combination with conventional treatments.

Stability and Association with the Cytomatrix of Mitochondrial DNA in Spontaneously Immortalized Mouse Embryo Fibroblasts Containing or Lacking the Intermediate Filament Protein Vimentin

To extend previous observations demonstrating differences in number, morphology, and activity of mitochondria in spontaneously immortalized vim(+) and vim(-) fibroblasts derived from wild-type and vimentin knockout mice, some structural and functional aspects of mitochondrial genome performance and integrity in both types of cells were investigated. Primary Vim(+/+) and Vim(-/-) fibroblasts, which escaped terminal differentiation by immortalization were characterized by an almost twofold lower mtDNA content in comparison to that of their primary precursor cells, whereby the average mtDNA copy number in two clones of vim(+) cells was lower by a factor of 0.6 than that in four clones of vim(-) cells. However, during serial subcultivation up to high passage numbers, the vim(+) and vim() fibroblasts increased their mtDNA copy number 1.5- and 2.5-fold, respectively. While early-passage cells of the vim(+) and vim(-) fibroblast clones differed only slightly in the ratio between mtDNA content and mitochondrial mass represented by mtHSP70 protein, after ca. 300 population doublings the average mtDNA/mtmass ratio in the vim(+) and vim() cells was increased by a factor of 2 and 4.5, respectively. During subcultivation, both types of cells acquired the fully transformed phenotype. These findings suggest that cytoskeletal vimentin filaments exert a strong influence on the mechanisms controlling mtDNA copy number during serial subcultivation of immortalized mouse embryo fibroblasts, and that vimentin deficiency causes a disproportionately enhanced mtDNA content in high-passage vim(-) fibroblasts. Such a role of vimentin filaments was supported by the stronger retention potential for mtDNA and mtDNA polymerase (gamma) detected in vim(+) fibroblasts by Triton X-100 extraction of mitochondria and agaroseembedded cells. Moreover, although the vim(+) and vim(-) fibroblasts were equally active in generating free radicals, the vim(-) cells exhibited higher levels of immunologically detectable 8-oxoG and mismatch repair proteins MSH2 and MLH1 in their mitochondria. Because in vim(-) fibroblasts only one point mutation was detected in the mtDNA D-loop control region, these cells are apparently able to efficiently remove oxidatively damaged nucleobases. On the other hand, a number of large-scale mtDNA deletions were found in high-passage vim(-) fibroblasts, but not in low-passage vim(-) cells and vim(+) cells of both low and high passage. Large mtDNA deletions were also induced in young vim(-) fibroblasts by treatment with the DNA intercalator ethidium bromide, whereas no such deletions were found after treatment of vim(+) cells. These results indicate that in immortalized vim(-) fibroblasts the mitochondrial genome is prone to large-scale rearrangements, probably due to insufficient control of mtDNA repair and recombination processes in the absence of vimentin.

Antioxidant enzymes and apoptosis

The role of antioxidant enzymes can be interpreted in terms of fine tuning of the concentration of reactive oxygen species which are required in the redox regulation of the cell cycle and of programmed cell death. This review summarizes findings from papers published in the last few years which deal with the relation between apoptosis and the two antioxidant enzymes, manganous superoxide dismutase (MnSOD) and catalase. With respect to MnSOD, the literature is much in favor of an inhibitory action in apoptosis. Increased MnSOD activity has been shown to prevent cell death via the receptor-mediated apoptotic pathway as well as cell death via the mitochondrial pathway. The literature on the influence of catalase activity on apoptosis is less consistent. Evidence for both an antiapoptotic and a proapoptotic role of catalase can be found. From the results reviewed here, two schemes for the involvement of MnSOD and catalase in the regulation of apoptosis can be extracted: 1) Both MnSOD and catalase inhibit apoptosis by removing superoxide anion radicals or H2O2, respectively, because these reactive oxygen species are mediators required for the apoptotic program or inhibit a survival pathway. 2) An increase in H2O2 by downregulation or inhibition of catalase activity and/or upregulation of MnSOD activity inhibits apoptosis while a decrease in H2O2 by upregulation of catalase activity and/or downregulation of MnSOD activity supports apoptosis, possibly because of a supportive role of H2O2 in a survival pathway. The data reported so far do not allow for an explanation why some cell models appear to fit the first scheme while the second scheme appears to correctly describe other cell models. The present state of the literature reveals that antioxidant enzymes play a more intricate role in cell physiology than previously assumed.

ROS stress in cancer cells and therapeutic implications

Reactive oxygen species (ROS) are constantly generated and eliminated in the biological system, and play important roles in a variety of normal biochemical functions and abnormal pathological processes. Growing evidence suggests that cancer cells exhibit increased intrinsic ROS stress, due in part to oncogenic stimulation, increased metabolic activity, and mitochondrial malfunction. Since the mitochondrial respiratory chain (electron transport complexes) is a major source of ROS generation in the cells, the vulnerability of the mitochondrial DNA to ROS-mediated damage appears to be a mechanism to amplify ROS stress in cancer cells. The escalated ROS generation in cancer cells serves as an endogenous source of DNA-damaging agents that promote genetic instability and development of drug resistance. Malfunction of mitochondria also alters cellular apoptotic response to anticancer agents. Despite the negative impacts of increased ROS in cancer cells, it is possible to exploit this biochemical feature and develop novel therapeutic strategies to preferentially kill cancer cells through ROS-mediated mechanisms. This article reviews ROS stress in cancer cells, its underlying mechanisms and relationship with mitochondrial malfunction and alteration in drug sensitivity, and suggests new therapeutic strategies that take advantage of increased ROS in cancer cells to enhance therapeutic activity and selectivity.

Iron and oxidative stress in renal insufficiency

BACKGROUND/AIMS

Iron (Fe) can cause tissue injury and oxidative stress by catalyzing hydroxyl radical production and lipid peroxidation. Intravenous (i.v.) Fe preparations are routinely administered to treat anemia in patients with chronic renal failure (CRF), a condition marked by oxidative stress and inflammation. In an earlier study, we showed that iron overload augments oxidative stress in the cardiovascular tissues of CRF rats. This study was designed to expand these observations to other major organs.

METHODS

Rats were randomized into CRF (5/6 nephrectomized) and sham-operated control (CTL) groups. Each group was subdivided into Fe-loaded (single i.v. injection of iron dextran complex, 0.5 g/kg) and placebo-treated subgroups. After 13 weeks, systolic blood pressure, blood hemoglobin (Hb), plasma Fe concentration, lipid peroxidation products, superoxide generating enzyme, NAD(P)H oxidase, and antioxidant enzymes were determined.

RESULTS

Systolic blood pressure was equally elevated and creatinine clearance was equally reduced in both CRF groups. Fe administration raised Hb, serum Fe and transferrin saturation in both CRF and CTL groups. The plasma concentration of lipid peroxidation product, malondialdehyde, was increased by Fe injection in CRF rats but not the control group. Renal tissue abundance of gp91(phox) subunit of NAD(P)H oxidase was elevated in the untreated CRF group and was partially reduced in the iron dextran-treated CRF group. Tissue abundance of the antioxidant enzymes; superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) were decreased in both untreated and iron dextran-treated CRF groups.

CONCLUSION

CRF resulted in marked SOD, CAT and GPX deficiencies. A single i.v. administration of iron dextran in rats with CRF induced oxidative stress as measured by increased lipid peroxidation products and decreases in antioxidant enzymes.

The effects of iron dextran on the oxidative stress in cardiovascular tissues of rats with chronic renal failure

BACKGROUND

Redox-active iron can promote oxidative stress and tissue injury by catalyzing hydroxyl radical generation and lipid peroxidation. Intravenous iron preparations are routinely administered in conjunction with erythropoietin to treat anemia in patients with chronic renal failure (CRF), a condition that is marked by oxidative stress and inflammation. This treatment frequently elevates iron burden, which can potentially intensify oxidative stress and, thus, cardiovascular disease in this population.

METHODS

We studied renal function and oxidative stress parameters in the cardiovascular tissues of CRF (5/6 nephrectomized) and sham-operated control rats 3 months after a single intravenous infusion of iron dextran (500 mg/kg).

RESULTS

Arterial pressure was equally elevated and creatinine clearance was equally reduced in both iron-treated and -untreated CRF groups. Iron administration significantly raised the blood hemoglobin, serum iron concentration, and transferrin saturation in both CRF and control groups. Iron administration resulted in a significant rise in plasma concentration of lipid peroxidation product, malondialdehyde in the CRF rats, and an insignificant rise in the control group. Plasma oxidized low-density lipoprotein (LDL) concentration was increased in the CRF groups, and was not affected by iron administrations. Iron administration raised nitrotyrosine abundance in the aorta of CRF but not in the control group. Left ventricular tissue abundance of p22(phox) subunit of NAD(P)H oxidase was elevated in CRF group and was not affected, whereas p67(phox) subunit abundance was raised by prior iron administration. Iron administration insignificantly lowered aorta p22(phox), but had no effect on p67(phox) subunit abundance in the treated CRF group. Previous iron administration significantly lowered superoxide dismutase and catalase abundance in the aorta and glutathione peroxidase in the left ventricle of CRF animals, but did not significantly change these parameters in the iron-treated control animals.

CONCLUSION

A single intravenous injection of iron dextran increased oxidative stress in the cardiovascular tissues in the CRF group, but not the control rats, pointing to heightened susceptibility to iron-mediated toxicity in CRF. However, administration of iron dextran did not adversely affect kidney function, and favorably affected hemoglobin concentration in rats with CRF induced by renal mass reduction. Further studies are needed to explore the effects of other parenteral iron preparations, repeated intravenous iron administration, and presence of comorbid conditions such as diabetes.

Intracellular oxidation by human glioma cell populations: effect of arachidonic acid

Arachidonic acid (AA) and Gamma linolenic acid have been shown to limit glioma cell growth, stimulate apoptosis and lipid peroxidation. However, brain tumours are characterised by cellular heterogeneity and responding cell populations have not been identified. Brain tumour samples from patients were disaggregated. In cell preparations from 7 gliomas, reactive oxygen species (ROS), morphology and plasma membrane integrity were monitored +/-18-36 microM AA for 15-120 min using flow cytometry. Basal oxidative activity related to cell size/morphology, small granular cells showed lower activity. AA stimulation of ROS formation depended on cell size/morphology. Large, less granular cells showed greater AA stimulation. In 17 gliomas, GFAP immunofluorescence was demonstrated in larger cell populations. The large GFAP positive cell population with low side scatter was the highest responding cell population, suggesting selective tumour cell sensitivity to AA induced ROS formation. ROS may have a role in AA induced cell death and anti-tumour activity of AA in glioma.

Incidence of apoptosis in clone embryos and improved development by the treatment of donor somatic cells with putative apoptosis inhibitors

This study was conducted to promote in vitro-development of clone embryos by the treatment of donor somatic cells with hemoglobin (Hb) and/or beta-mercaptoethanol (ME), based on the analysis of apoptosis after somatic cell nuclear transfer (SCNT). Prospective, randomized study was conducted and, in vitro-matured bovine oocytes and fetal fibroblasts were provided for SCNT. In the first series of experiment, embryo apoptosis after SCNT was monitored by a terminal deoxynucleotidyl transferase-mediated d-UTP nick end-labeling assay. As results, apoptosis occurred more (P < 0.05) frequently after SCNT than after in vitro-fertilization (IVF) of control treatment. Subsequently, donor somatic cells treated with Hb (1 microg/ml) and/or ME (10 microM) were provided for SCNT. Either Hb or ME greatly reduced apoptosis (0.083 +/- 0.006 vs. 0.058-0.068 +/- 0.005), while combined treatment did not. ME was more promotive than Hb; significant increases were found in morula compaction (86%), cell numbers of blastocyst (131.3 +/- 1.3 cells/blastocyst), and inner cell mass (31.9 +/- 0.8 cells/blastocyst) cell, and the ratio of inner cell mass to trophectodermal cell numbers (0.24 +/- 0.01). In conclusion, the treatment of donor somatic cells with ME or Hb could reduce apoptosis after SCNT, resulting improved preimplantation development.

Association of gp91phox homolog Nox1 with anchorage-independent growth and MAP kinase-activation of transformed human keratinocytes

Among five members of the NADPH oxidase (Nox) family, Nox1 confers mitogenic properties and is implicated to participate in the process of cell transformation. We have established two phenotypes of carcinogenesis model by ethanol treatment of human gingival keratinocytes immortalized with E6/E7 oncogenes of human papillomavirus type16: immortalized (EPI) nontransformed cells with epithelium-like morphology and more advanced transformed (FIB) cells with spindle fibroblastic-shape morphology. FIB membranes possessed a 63-kDa Nox1 protein at higher levels and exhibited 2.8-fold higher capability for superoxide and hydroxyl radical generation, compared with EPI membranes. Both EPI and FIB cells expressed more abundant Nox1 protein at a proliferating stage than that at a quiescent confluent phase. Immunofluorescence staining with an anti-Nox1 antibody showed that immunoreactive materials were distributed in the whole interior of both types of cells, while they were preferentially localized in the nuclei of FIB cells. Nuclei isolated from EPI and FIB cells contained a 63 kDa-Nox1 protein. Compared with EPI cells, FIB cells expressed elevated levels of Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase proteins. Furthermore, JNK2 was constitutively phosphorylated in FIB cells. Together, our data strongly implicate Nox1 in redox-mediated signaling related to cellular activation of human keratinocytes at a more advanced stage of transformation.

Improved embryo development with decreased apoptosis in blastomeres after the treatment of cloned bovine embryos with ?-mercaptoethanol and hemoglobin

In preliminary experiments, the treatment of donor somatic cells with beta-mercaptoethanol (ME) or hemoglobin (Hb) improved in vitro-development of bovine cloned embryos. This study was subsequently evaluated whether the exposure to Hb and/or ME during in vitro-maturation or embryo culture could further promote the development of embryos cloned with ME-treated donor cells. A prospective, randomized study was conducted and, embryo development, cell number, and apoptosis in blastocysts were monitored. A significant (P < 0.05) effect was found after the combined treatment of cloned embryos with Hb (1 microg/ml) and ME (10 microM); the development of morulae (53 vs. 35%) was greatly improved, which resulted in enhanced blastocyst formation (38%). However, cell number and apoptosis in blastocysts were predominantly affected by ME rather than Hb; a significant increase in total cell number of blastomeres (142-154 vs. 123 cells/embryo), inner cell mass (ICM) (39-41 vs. 27), and trophectoderm (TE) (103-114 vs. 98), and the ratio of ICM to TE cell number (0.26-0.27 vs. 0.22) was found. Also, the apoptosis index indicating the ratio of apoptotic cell to normal blastomere number was greatly reduced after ME treatments (0.85 vs. 0.056-0.069). When embryos cloned with ME-treated cells were cultured in Hb + ME-containing medium, any of the treatments to recipient oocytes before enucleation did not further promote the development. In conclusion, combined treatment of cloned embryos with Hb + ME not only improved in vitro-development but also decreased blastomere apoptosis. The use of ME-treated donor cells and the culture of cloned embryos in Hb + ME-containing medium yielded the optimal results for promoting the production of blastocysts with improved quality.