Reactive oxygen species: role in the development of cancer and various chronic conditions

Association of alanine-valine manganese superoxide dismutase gene polymorphism and microheterogeneity manganese superoxide dismutase activity in breast cancer and benign breast tissue

PURPOSE

Although the etiology of breast cancer is multifactorial, oxidative stress plays an important role in carcinogenesis. In this study, manganese superoxide dismutase (MnSOD) gene polymorphism and activity were evaluated in benign and breast cancer tissue.

METHODS

One hundred and one females were enrolled in this study, 65 who were histopathologically diagnosed with breast cancer and 46 who were benign patients. MnSOD enzyme activity was determined using an indirect competitive inhibition assay and MnSOD gene polymorphism using poly merase chain reaction and agarose gel electrophoresis.

RESULTS

MnSOD enzymatic activity (79.83±42.14) was lower in breast cancer tissue compared to benign tumors (236.18±46.37). At the same time, MnSOD enzymatic activity among Ala/Val patients was significantly lower in breast cancer tissue (39.19±7.33) than in Val/Val malignant breast tumors tissue (96.9±22.9). MnSOD enzymatic activity was significantly lower in Val/Val cancer tissue (96.9±22.9) than in benign tissue (255.44±42.7).

CONCLUSION

Breast cancer tumors contain less MnSOD than benign breast samples. Patients with Ala/Val polymorphism had reduced MnSOD activity compared to patients with Val/Val breast cancer. Ala/Val gene polymorphism may be a risk factor associated with more advanced breast cancer stage. MnSOD gene polymorphism Ala/Val may be a risk factor associated with more advanced breast cancer stage, and reduction of MnSOD activity may be a mechanism of the progression of benign to malignant tumors. Further investigations are needed to evaluate the role of MnSOD in breast cancer progression.

Upregulation of TLR1, TLR2, TLR4, and IRAK-2 Expression During ML-1 Cell Differentiation to Macrophages: Role in the Potentiation of Cellular Responses to LPS and LTA

12-O-tetradecanoylphorbol 13-acetate (TPA) induces the differentiation of human myeloid ML-1 cells to macrophages. In the current study, the expression, responsiveness, and regulation of toll-like receptors (TLRs) in TPA-induced ML-1-derived macrophages were investigated. We have found that TPA-induced differentiation of ML-1 cells was accompanied by the upregulation of TLR1, TLR2, TLR4, and CD14 expression at both the mRNA and protein levels. Interestingly, TLR1 and TLR4 protein expression on ML-1 cells could be blocked by pretreatment with U0126, suggesting the role of an Erk1/2-induced differentiation signal in this process. In addition, the expression of IRAK-2, a key member of the TLR/IRAK-2/NF-κB-dependent signaling cascade was also induced in response to TPA. Accordingly, we demonstrated an increased cellular release of inflammatory cytokines (TNF-α and various interleukins) upon stimulation with LPS and LTA ligands for TLR4 and TLR2, respectively. Furthermore, using luminol-dependent chemiluminescence, addition of LPS and LTA induces a sustained DPI-inhibitable generation of reactive oxygen species (ROS) by the differentiated ML-1 cells. Together, these data suggest that the increase in the responsiveness of TPA-treated ML-1 cells to LPS and LTA occurs in response to the upregulation of their respective receptors as well as an induction of the IRAK-2 gene expression.

Induction of apoptosis by casticin in cervical cancer cells: reactive oxygen species-dependent sustained activation of Jun N-terminal kinase

Casticin, a polymethoxyflavone from Fructus viticis used as an anti-inflammatory agent in Chinese traditional medicine, has been reported to have anti-cancer activity. The purpose of this study was to examine the apoptotic activity of casticin on human cervical cancer cells and its molecular mechanism. We revealed a novel mechanism by which casticin-induced apoptosis occurs and showed for the first time that the apoptosis induced by casticin is mediated through generation of reactive oxygen species (ROS) and sustained activation of c-Jun N-terminal kinase (JNK) in HeLa cells. Casticin markedly increased the levels of intracellular ROS and induced the expression of phosphorylated JNK and c-Jun protein. Pre-treatment with N-acetylcysteine and SP600125 effectively attenuated induction of apoptosis by casticin in HeLa cells. Moreover, casticin induced ROS production and apoptotic cell death in other cervical cancer cell lines, such as CasKi and SiHa. Importantly, casticin did not cause generation of ROS or induction of apoptosis in normal human peripheral blood mononuclear cells and embryonic kidney epithelium 293 cells. These results suggest that ROS generation and sustained JNK activation by casticin play a role in casticin-induced apoptosis and raise the possibility that treatment with casticin might be promising as a new therapy against human cervical cancer.

Tetrathiomolybdate sensitizes ovarian cancer cells to anticancer drugs doxorubicin, fenretinide, 5-fluorouracil and mitomycin C

BACKGROUND

Our recent study showed that tetrathiomolybdate (TM), a drug to treat copper overload disorders, can sensitize drug-resistant endometrial cancer cells to reactive oxygen species (ROS)-generating anticancer drug doxorubicin. To expand these findings in the present study we explore TM efficacy in combination with a spectrum of ROS-generating anticancer drugs including mitomycin C, fenretinide, 5-fluorouracil and doxorubicin in ovarian cancer cells as a model system.

METHODS

The effects of TM alone or in combination with doxorubicin, mitomycin C, fenretinide, or 5-fluorouracil were evaluated using a sulforhodamine B assay. Flow cytometry was used to detect the induction of apoptosis and ROS generation. Immunoblot analysis was carried out to investigate changes in signaling pathways.

RESULTS

TM potentiated doxorubicin-induced cytotoxicity and modulated key regulators of apoptosis (PARP, caspases, JNK and p38 MAPK) in SKOV-3 and A2780 ovarian cancer cell lines. These effects were linked to the increased production of ROS, as shown in SKOV-3 cells. ROS scavenging by ascorbic acid blocked the sensitization of cells by TM. TM also sensitized SKOV-3 to mitomycin C, fenretinide, and 5-fluorouracil. The increased cytotoxicity of these drugs in combination with TM was correlated with the activity of ROS, loss of a pro-survival factor (e.g. XIAP) and the appearance of a pro-apoptotic marker (e.g. PARP cleavage).

CONCLUSIONS

Our data show that TM increases the efficacy of various anticancer drugs in ovarian cancer cells in a ROS-dependent manner.

4-Ketopinoresinol, a novel naturally occurring ARE activator, induces the Nrf2/HO-1 axis and protects against oxidative stress-induced cell injury via activation of PI3K/AKT signaling

The Nrf2/ARE pathway plays an important role in inducing phase II detoxifying enzymes and antioxidant proteins and has been considered a potential target for cancer chemoprevention because it eliminates harmful reactive oxygen species or reactive intermediates generated from carcinogens. The objectives of this study were to identify novel Nrf2/ARE activators and to investigate the mechanistic signaling pathway involved in the activation of Nrf2-mediated cytoprotective effects against oxidative-induced cell injury. A stable ARE-driven luciferase reporter cell line was established to screen a potentially cytoprotective compound. 4-Ketopinoresinol (4-KPR), the (α-γ) double-cyclized type of lignan obtained from adlay (Coix lachryma-jobi L. var. ma-yuen Stapf), activates ARE-driven luciferase activity more effectively than the classical ARE activator tert-butylhydroquinone. 4-KPR treatment resulted in a transient increase in AKT phosphorylation and subsequent phosphorylation and nuclear translocation of Nrf2, along with increased expression of ARE-dependent cytoprotective genes, such as heme oxygenase-1 (HO-1), aldo-keto reductases, and glutathione synthetic enzyme. 4-KPR suppresses oxidative stress-induced DNA damage and cell death via upregulation of HO-1. Inhibition of PI3K/AKT signaling by chemical inhibitors or RNA interference not only suppressed 4-KPR-induced Nrf2/HO-1 activation, but also eliminated the cytoprotective effect against oxidative damage. These observations in an ARE-regulated gene system suggest that 4-KPR is a novel Nrf2/ARE-mediated transcription activator, activates the Nrf2/HO-1 axis, and protects against oxidative stress-induced cell injury via activation of PI3K/AKT signaling.

Regulation of suppressive function of myeloid-derived suppressor cells by CD4+ T cells

Myeloid derived suppressor cells play a critical role in T cell suppression in cancer. Here, we discuss the mechanisms of how MDSC suppress CD4(+) or CD8(+) T cells in an antigen dependent or non-dependent manner.

Clair DK. Manganese superoxide dismutase: beyond life and death

Manganese superoxide dismutase (MnSOD) is a nuclear-encoded antioxidant enzyme that localizes to the mitochondria. Expression of MnSOD is essential for the survival of aerobic life. Transgenic mice expressing a luciferase reporter gene under the control of the human MnSOD promoter demonstrate that the level of MnSOD is reduced prior to the formation of cancer. Overexpression of MnSOD in transgenic mice reduces the incidences and multiplicity of papillomas in a DMBA/TPA skin carcinogenesis model. However, MnSOD deficiency does not lead to enhanced tumorigenicity of skin tissue similarly treated because MnSOD can modulate both the p53-mediated apoptosis and AP-1-mediated cell proliferation pathways. Apoptosis is associated with an increase in mitochondrial levels of p53 suggesting a link between MnSOD deficiency and mitochondrial-mediated apoptosis. Activation of p53 is preventable by application of a SOD mimetic (MnTE-2-PyP(5+)). Thus, p53 translocation to mitochondria and subsequent inactivation of MnSOD explain the observed mitochondrial dysfunction that leads to transcription-dependent mechanisms of p53-induced apoptosis. Administration of MnTE-2-PyP(5+) following apoptosis but prior to proliferation leads to suppression of protein carbonyls and reduces the activity of AP-1 and the level of the proliferating cellular nuclear antigen, without reducing the activity of p53 or DNA fragmentation following TPA treatment. Remarkably, the incidence and multiplicity of skin tumors are drastically reduced in mice that receive MnTE-2-PyP(5+) prior to cell proliferation. The results demonstrate the role of MnSOD beyond its essential role for survival and suggest a novel strategy for an antioxidant approach to cancer intervention.

Additive antinociceptive effects of a combination of vitamin C and vitamin E after peripheral nerve injury

Accumulating evidence indicates that increased generation of reactive oxygen species (ROS) contributes to the development of exaggerated pain hypersensitivity during persistent pain. In the present study, we investigated the antinociceptive efficacy of the antioxidants vitamin C and vitamin E in mouse models of inflammatory and neuropathic pain. We show that systemic administration of a combination of vitamins C and E inhibited the early behavioral responses to formalin injection and the neuropathic pain behavior after peripheral nerve injury, but not the inflammatory pain behavior induced by Complete Freund's Adjuvant. In contrast, vitamin C or vitamin E given alone failed to affect the nociceptive behavior in all tested models. The attenuated neuropathic pain behavior induced by the vitamin C and E combination was paralleled by a reduced p38 phosphorylation in the spinal cord and in dorsal root ganglia, and was also observed after intrathecal injection of the vitamins. Moreover, the vitamin C and E combination ameliorated the allodynia induced by an intrathecally delivered ROS donor. Our results suggest that administration of vitamins C and E in combination may exert synergistic antinociceptive effects, and further indicate that ROS essentially contribute to nociceptive processing in special pain states.

Carotenoid exposure of Caco-2 intestinal epithelial cells did not affect selected inflammatory markers but altered their proteomic response

Carotenoid consumption has been linked to a number of beneficial health effects, including the reduction of chronic diseases such as cancer and cardiovascular complications. However, no data are available on their action on the intestinal epithelium, being exposed to the highest concentrations of carotenoids in the human body, and where they could act preventively on intestinal inflammatory diseases such as Crohn's disease and ulcerative colitis. The objective of the present study was to investigate whether lycopene and β-carotene in micelles (M), at concentrations that could be reached via the diet (10-25 μg/ml) could aid in the reduction of TNF-α plus IL-1β-induced inflammation of Caco-2 human epithelial cells. The impact on biomarkers of inflammation, including IL-8, NO and cyclo-oxygenase-2 (through PGE-2α), and the NF-κB and mitogen-activated protein kinase (MAPK) pathways of intracellular signalling cascades were evaluated compared with controls (empty M). Furthermore, proteomic analyses were conducted from total cellular protein extracts. The results revealed that isolated carotenoids had no statistical significant anti-inflammatory effect on the biomarkers observed, or on the regulation of NF-κB and MAPK. Nevertheless, analyses of the proteome suggested that fifteen proteins were significantly (P < 0·05, expression ratio >1·3) differentially regulated following β-carotene exposure, participating mostly in metabolic activities including antioxidant mechanisms, such as glutathione S-transferase A1. Only one protein was differentially regulated by lycopene (profilin-1). To our knowledge, this is the first attempt to investigate pathways involved in the action of carotenoids on the intestinal epithelium.

Genetic polymorphism of the glutathione-S-transferase P1 gene (GSTP1) and susceptibility to prostate cancer in the Kashmiri population

Glutathione-S-transferase P1 (GSTP1) is a critical enzyme of the phase II detoxification pathway. One of the common functional polymorphisms of GSTP1 is A→G at nucleotide 313, which results in an amino acid substitution (Ile105Val) at the substrate binding site of GSTP1 and reduces catalytic activity of GSTP1. To investigate the GSTP1 Ile105Val genotype frequency in prostate cancer cases in the Kashmiri population, we designed a case-control study, in which 50 prostate cancer cases and 45 benign prostate hyperplasia cases were studied for GSTP1 Ile105Val polymorphism, compared to 80 controls taken from the general population, employing the PCR-RFLP technique. We found the frequency of the three different genotypes of GSTP1 Ile105Val in our ethnic Kashmir population, i.e., Ile/Ile, Ile/Val and Val/Val, to be 52.4, 33.3 and 14.3% among prostate cancer cases, 48.5, 37.5 and 14% among benign prostate hyperplasia cases and 73.8, 21.3 and 5% in the control population, respectively. There was a significant association between the GSTP1 Ile/Val genotype and the advanced age group among the cases. We conclude that GSTP1 Ile/Val polymorphism is involved in the risk of prostate cancer development in our population.

Age-related differences in cigarette smoke extract-induced H2O2 production by lung endothelial cells

Cigarette smoke causes oxidative stress in the lung resulting in injury and disease. The purpose of this study was to determine if there were age-related differences in cigarette smoke extract (CSE)-induced production of reactive species in single and co-cultures of alveolar epithelial type I (AT I) cells and microvascular endothelial cells harvested from the lungs (MVECLs) of neonatal, young and old male Fischer 344 rats. Cultures of AT I cells and MVECLs grown separately (single culture) and together (co-culture) were exposed to CSE (1, 10, 50, 100%). Cultures were assayed for the production of intracellular reactive oxygen species (ROS), hydroxyl radical (OH), peroxynitrite (ONOO(-)), nitric oxide (NO) and extracellular hydrogen peroxide (H(2)O(2)). Single and co-cultures of AT I cells and MVECLs from all three ages produced minimal intracellular ROS in response to CSE. All ages of MVECLs produced H(2)O(2) in response to CSE, but young MVECLs produced significantly less H(2)O(2) compared to neonatal and old MVECLs. Interestingly, when grown as a co-culture with age-matched AT I cells, neonatal and old MVECLs demonstrated ~50% reduction in H(2)O(2) production in response to CSE. However, H(2)O(2) production in young MVECLs grown as a co-culture with young AT I cells did not change with CSE exposure. To begin investigating for a potential mechanism to explain the reduction in H(2)O(2) production in the co-cultures, we evaluated single and co-cultures for extracellular total antioxidant capacity. We also performed gene expression profiling specific to oxidant and anti-oxidant pathways. The total antioxidant capacity of the AT I cell supernatant was ~5 times greater than that of the MVECLs, and when grown as a co-culture and exposed to CSE (≥ 10%), the total antioxidant capacity of the supernatant was reduced by ~50%. There were no age-related differences in total antioxidant capacity of the cell supernatants. Gene expression profiling found eight genes to be significantly up-regulated or down-regulated. This is the first study to describe age-related differences in MVECLs exposed to CSE.

Clair DK. Manganese superoxide dismutase: guardian of the powerhouse

The mitochondrion is vital for many metabolic pathways in the cell, contributing all or important constituent enzymes for diverse functions such as β-oxidation of fatty acids, the urea cycle, the citric acid cycle, and ATP synthesis. The mitochondrion is also a major site of reactive oxygen species (ROS) production in the cell. Aberrant production of mitochondrial ROS can have dramatic effects on cellular function, in part, due to oxidative modification of key metabolic proteins localized in the mitochondrion. The cell is equipped with myriad antioxidant enzyme systems to combat deleterious ROS production in mitochondria, with the mitochondrial antioxidant enzyme manganese superoxide dismutase (MnSOD) acting as the chief ROS scavenging enzyme in the cell. Factors that affect the expression and/or the activity of MnSOD, resulting in diminished antioxidant capacity of the cell, can have extraordinary consequences on the overall health of the cell by altering mitochondrial metabolic function, leading to the development and progression of numerous diseases. A better understanding of the mechanisms by which MnSOD protects cells from the harmful effects of overproduction of ROS, in particular, the effects of ROS on mitochondrial metabolic enzymes, may contribute to the development of novel treatments for various diseases in which ROS are an important component.

Epitaxial growth of the zinc oxide nanorods, their characterization and in vitro biocompatibility studies

Here, we have synthesized Zinc Oxide (ZnO) nanorods at room temperature using zinc acetate and hexamethylenetetramine as precursors followed by characterization using X-ray diffraction (XRD), fourier transform infra red spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy. The growth of the synthesized ZnO was found to be very close to its hexagonal nature, which is confirmed by XRD. The nanorods were grown perpendicular to the long-axis and grew along the [001] direction, which is the nature of ZnO growth. The morphology of the synthesized ZnO nanorods was also confirmed by SEM. The size of the nanorod was estimated to be around 20-25 nm in diameter and approximately 50-60 nm in length. Our biocompatibility studies using synthesized ZnO showed no significant dose- or time-dependent increase in the formation of free radicals, accumulation of peroxidative products, antioxidant depletion or loss of cell viability on lung epithelial cells.

Bio-screening of a few green seaweeds from India for their cytotoxic and antioxidant potential

BACKGROUND

It has been evidenced in several epidemiological studies that seaweeds when consumed as diet protect against several chronic oxidative stress-related diseases. Seaweeds, raw, cooked, or dried, are used as food in many cultures, although not very popularly in India. Globally, several studies have indicated that seaweeds are a rich source of phenolic compounds and have antioxidant properties. In the present study, we screened methanolic extracts (MEs) of five species of green seaweeds commonly found in India for their cytotoxic activity by brine shrimp lethality assay and antioxidant properties using various in vitro assays, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, reducing power and metal ion chelating assays.

RESULTS

A markedly variable, dose-dependent activity was observed in all the seaweed extracts relative to their total phenolic content. Statistical analysis indicated a significantly strong correlation between the DPPH radical scavenging activity and total phenolic content (R(2) = 0.88, P < 0.05) as well as reducing power and total phenolic content (R(2) = 0.99, P < 0.01) of the dry MEs. Also, a very poor correlation between total phenolic content and metal chelating activity (R(2) = 0.13, P > 0.05) was noted. None of the seaweed extracts were potently cytotoxic.

CONCLUSION

The underlying results endorse seaweeds as a rich, novel source of antioxidant compounds needing systemic exploration.

Involvement of reactive oxygen species in 2-methoxyestradiol-induced apoptosis in human neuroblastoma cells

Neuroblastoma is the most common extra-cranial solid tumor in children. Despite advances in the treatment of childhood cancer, outcomes for children with advanced-stage neuroblastoma remain poor. Here we reported that 2-methoxyestradiol (2-ME) inhibited the proliferation and induced apoptosis in human neuroblastoma SK-N-SH and SH-SY5Y cells. 2-ME treatment also resulted in the generation of ROS and the loss of mitochondrial membrane potential in SK-N-SH and SH-SY5Y, indicating that 2-ME-induced apoptosis is mediated by ROS. This is supported by the results that have shown that co-treatment with antioxidants, VC, L-GSH and MitoQ(10), decreased 2-ME-induced generation of ROS and the loss of the mitochondrial membrane potential, increased the Bcl-2/Bax ratio, decreased 2-ME-induced activation of caspase-9 and caspase-3 and the up-regulation of apoptosis-inducing factor (AIF), and prevented 2-ME-induced apoptosis in SK-N-SH and SH-SY5Y cells. These results suggested that oxidative stress plays an important role in 2-ME-induced apoptotic death of human neuroblastoma cells.

Studies on the potential antioxidant properties of Senecio stabianus Lacaita (Asteraceae) and its inhibitory activity against carbohydrate-hydrolysing enzymes

This study showed for the first time the antioxidant and hypoglycaemic properties of the methanol, n-hexane and ethyl acetate extracts from Senecio stabianus Lacaita, a plant that belongs to the Asteraceae family. The antioxidant activities were carried out using two different in vitro assays, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH) test and 2,2'-azinobis(3-ethylbenzthiazoline-6-sulphonate) (ABTS) test. The ethyl acetate extract showed the highest activity with inhibitory concentration 50% (IC(50)) values of 35.5 and 32.7 µg mL(-1) on DPPH test and ABTS test, respectively. This activity may be related to a good total phenol and flavonoid content. All extracts were also tested for their potential inhibitory activity of α-amylase and α-glucosidase digestive enzymes. The n-hexane extract exhibited the highest α-amylase inhibition with an IC(50) value of 0.21 mg mL(-1). Through bioassay-guided fractionation processes seven fractions (A-G) were obtained and tested. Based on the phytochemical analysis, the activity of n-hexane extract may be related to the presence of monoterpenes and sesquiterpenes.

Eight weeks of conjugated linoleic acid supplementation has no effect on antioxidant status in healthy overweight/obese Korean individuals

PURPOSE

The aim of this study was to evaluate the effect of CLA supplementation on antioxidant metabolism in healthy overweight/obese Korean individuals.

METHODS

We performed a randomized, double-blind, placebo-controlled trial, where 29 healthy overweight/obese (BMI ≥ 23 kg/m(2)) participants (2 men and 27 women) were randomly selected to receive placebo (n = 15, 2.4 g olive oil/day) or 2.4 g/day CLA mixture (n = 14, 36.9% of cis-9, trans-11 and 37.9% of trans-10, cis-12) for 8 weeks.

RESULTS

There were no significant differences in plasma total radical-trapping antioxidant potential (TRAP), lipid peroxidation (conjugated dienes), lipid-soluble antioxidant vitamin concentration, erythrocyte antioxidant enzyme (superoxide dismutase, catalase, glutathione peroxidase) activities, and leukocyte DNA damage between the CLA and placebo groups.

CONCLUSIONS

The data suggest that short-term supplementation (8 weeks) with CLA (2.4 g/day) might have no significant effects on lipid peroxidation and antioxidant metabolism.

Organometallic iron(III)-salophene exerts cytotoxic properties in neuroblastoma cells via MAPK activation and ROS generation

The objective of the present study was to investigate the specific effects of Iron(III)-salophene (Fe-SP) on viability, morphology, proliferation, cell cycle progression, ROS generation and pro-apoptotic MAPK activation in neuroblastoma (NB) cells. A NCI-DTP cancer screen revealed that Fe-SP displayed high toxicity against cell lines of different tumor origin but not tumor type-specificity. In a viability screen Fe-SP exhibited high cytotoxicity against all three NB cell lines tested. The compound caused cell cycle arrest in G1 phase, suppression of cells progressing through S phase, morphological changes, disruption of the mitochondrial membrane depolarization potential, induction of apoptotic markers as well as p38 and JNK MAPK activation, DNA degradation, and elevated generation of reactive oxygen species (ROS) in SMS-KCNR NB cells. In contrast to Fe-SP, non-complexed salophene or Cu(II)-SP did not raise ROS levels in NB or SKOV-3 ovarian cancer control cells. Cytotoxicity of Fe-SP and activation of caspase-3, -7, PARP, pro-apoptotic p38 and JNK MAPK could be prevented by co-treatment with antioxidants suggesting ROS generation is the primary mechanism of cytotoxic action. We report here that Fe-SP is a potent growth-suppressing and cytotoxic agent for in vitro NB cell lines and, due to its high tolerance in previous animal toxicity studies, a potential therapeutic drug to treat NB tumors in vivo.

Intracellular reactive oxygen species are essential for PI3K/Akt/mTOR-dependent IL-7-mediated viability of T-cell acute lymphoblastic leukemia cells

Interleukin-7 (IL-7) activates phosphoinositide 3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway, thereby mediating viability, proliferation and growth of T-cell acute lymphoblastic leukemia (T-ALL) cells. Reactive oxygen species (ROS) can be upregulated by growth factors and are known to regulate proliferation and viability. Here, we show that IL-7 upregulates ROS in T-ALL cells in a manner that is dependent on PI3K/Akt/mTOR pathway activity and that relies on both NADPH oxidase and mitochondrial respiratory chain. Conversely, IL-7-induced activation of PI3K signaling pathway requires mitochondrial respiration and ROS. We have previously shown that IL-7-mediated activation of PI3K pathway drives the upregulation of the glucose transporter Glut1, promoting glucose uptake in T-ALL cells. Using phloretin to inhibit Glut function, we demonstrate that glucose uptake is mandatory for ROS upregulation in IL-7-treated T-ALL cells, suggesting that IL-7 stimulation leads to increased ROS via PI3K pathway activation and consequent upregulation of Glut1 and glucose uptake. Overall, our data reveal the existence of a critical crosstalk between PI3K/Akt signaling pathway and ROS that is essential for IL-7-mediated T-ALL cell survival, and that may constitute a novel target for therapeutic intervention.

Mythology of Antioxidant Vitamins?

Decades of overly exuberant antioxidant vitamin claims, regarding disease prevention and antiaging, have not been supported by rigorous scientific testing and negative studies have been largely denied or ignored by the dietary supplement industry. Myths, half truths, and outright lies are commonly used to promote their sales since there is minimal governmental oversight of their effectiveness or of their harmful potential. The free radical theory, which served as the basis of antioxidant vitamin studies to prevent disease, lacks predictability, fails to meet the requirements of the scientific method, and has consequently been invalidated. Antioxidant vitamins have such widespread use that their potential to do harm has become a global public health issue. We must follow the fundamental medical precept of Hippocrates: ‘‘First, do no harm.’’ We must separate fact from factitious and ‘‘myths of marketing’’ from scientific truths.

Mieap, a p53-inducible protein, controls mitochondrial quality by repairing or eliminating unhealthy mitochondria

Maintenance of healthy mitochondria prevents aging, cancer, and a variety of degenerative diseases that are due to the result of defective mitochondrial quality control (MQC). Recently, we discovered a novel mechanism for MQC, in which Mieap induces intramitochondrial lysosome-like organella that plays a critical role in the elimination of oxidized mitochondrial proteins (designated MALM for Mieap-induced accumulation of lysosome-like organelles within mitochondria). However, a large part of the mechanisms for MQC remains unknown. Here, we report additional mechanisms for Mieap-regulated MQC. Reactive oxygen species (ROS) scavengers completely inhibited MALM. A mitochondrial outer membrane protein NIX interacted with Mieap in a ROS-dependent manner via the BH3 domain of NIX and the coiled-coil domain of Mieap. Deficiency of NIX also completely impaired MALM. When MALM was inhibited, Mieap induced vacuole-like structures (designated as MIV for Mieap-induced vacuole), which engulfed and degraded the unhealthy mitochondria by accumulating lysosomes. The inactivation of p53 severely impaired both MALM and MIV generation, leading to accumulation of unhealthy mitochondria. These results suggest that (1) mitochondrial ROS and NIX are essential factors for MALM, (2) MIV is a novel mechanism for lysosomal degradation of mitochondria, and (3) the p53-Mieap pathway plays a pivotal role in MQC by repairing or eliminating unhealthy mitochondria via MALM or MIV generation, respectively.

Antioxidant, antiproliferative, and pro-apoptotic capacities of pentacyclic triterpenes found in the skin of olives on MCF-7 human breast cancer cells and their effects on DNA damage

This research aimed to investigate erythrodiol, uvaol, oleanolic acid, and maslinic acid scavenging capacities and their effects on cytotoxicity, cell proliferation, cell cycle, apoptosis, reactive oxygen species (ROS) level, and oxidative DNA damage on human MCF-7 breast cancer cell line. The results showed that erythrodiol, uvaol, and oleanolic acid have a significant cytotoxic effect and inhibit proliferation in a dose- and time-dependent manner. At 100 μM, erythrodiol growth inhibition occurred through apoptosis, with the observation of important ROS production and DNA damage, whereas uvaol and oleanolic acid growth inhibition involved cell cycle arrest. Moreover, although all tested triterpenes did not show free radical scavenging activity using ABTS and DPPH assays, they protected against oxidative DNA damage at the concentration 10 μM. Uvaol and oleanolic and maslinic acids, tested at 10 and 100 μM, also reduced intracellular ROS level and prevented H(2)O(2)-induced oxidative injury. Overall, the results suggest that tested triterpenes may have the potential to provide significant natural defense against human breast cancer.

TRANSCRIPTIONAL AND PHOSPHO-PROTEOMIC SCREENS REVEAL STEM CELL ACTIVATION OF INSULIN-RESISTANCE AND TRANSFORMATION PATHWAYS FOLLOWING A SINGLE MINIMALLY TOXIC EPISODE OF ROS

Elevated reactive oxidative species (ROS) are cytotoxic, and chronic elevated levels of ROS have been implicated in multiple diseases as well as cellular transformation and tumor progression. However, the potential for a transient and minimally toxic episode of ROS exposure, or a minimal threshold dose of ROS, to initiate disease or cellular transformation is unclear. We examined both transcriptional and phospho-proteomic responses of murine embryonic stem (ES) cells to a single brief exposure of minimally toxic hydrogen peroxide (H(2)O(2)). The cellular response was distinct from those induced by either an acute exposure to H(2)O(2) or the topoisomerase II poison etoposide. Analysis of tumorigenesis-related transcripts revealed a significant up-regulation of oncogenes and down-regulation of tumor suppressors. Analysis of the phospho-proteomic response demonstrated insulin-signaling induction, including insulin receptor Y972 hypophosphorylation, similar to insulin-resistance mouse models and observed in diabetic patients. In addition, ES cells were more resistant to ROS than differentiated cells, and retained their transcriptional self-renewal signature, suggesting stem cells have a higher potential for ROS-mediated mutagenesis and proliferation in vivo. These results are a direct demonstration that even brief and non-toxic exposures to ROS may induce transduction of insulin resistance and transformation signaling in stem cells leading to diabetes and cancer.

Protective effect of trifluoperazine on hydrogen peroxide-induced apoptosis in PC12 cells

This study investigated effects of trifluoperazine (TFP) against the cytotoxicity induced by H₂O₂ in PC12 cells and the mechanisms thereof. Different concentrations of H₂O₂ (100-500 μM) induced a significant decrease in cell viability accompanied by increased oxidative stress and cell apoptosis. Pretreatment with TFP inhibited H₂O₂-induced cell viability loss. The flow cytometric assay showed that TFP can inhibit intracellular reactive oxygen species (ROS) generation and reduce the cell apoptosis. The electrophysiological recordings indicated that when treated with H₂O₂, the calcium current was significantly increased. Pretreatment with TFP increased mitochondrial membrane potential (MMP) in cells of oxidative injury. These results suggested that TFP can reduce apoptosis by inhibiting ROS generation and preventing loss of MMP in cells. Meanwhile, the protective effect of TFP on the cell apoptosis may be related to the calcium overload. TFP may inhibit the calcium overload process to achieve the protection against apoptosis.

Myeloid-derived suppressor cells in human cancer

Myeloid-derived suppressor cells are one of the major factors responsible for immune suppression in cancer. They also contribute to limited efficacy of current vaccination strategies. Here, we give an overview of the myeloid-derived suppressor cells field focusing primarily on the studies in cancer patients and current and future therapeutic options targeting these cells.

RETRACTED: REDOX regulation of IL-13 signaling in intestinal epithelial cells: usage of alternate pathways mediates distinct gene expression patterns

In the classic view interleukin-13 (IL-13) binds to a heterodimer protein complex of the IL-13Ralpha1 and IL-4Ralpha chains and signals through a Janus kinase 1 (JAK1)-signal transducer and activator of transcription 6 (STAT6) mechanism. We recently reported that IL-13 also signals through the IL-13Ralpha2 chain initiating all three mitogen activated protein kinase (MAPK) pathways, and the relative expression of IL-13Ralpha1 and IL-13Ralpha2 modulates one another's transduction pathway. Therefore we investigated whether generation of reactive oxygen species (ROS) as second messengers may serve as a common nexus between these two pathways emanating from the individual IL-13 receptor chains in intestinal epithelial cells (IEC). IL-13 stimulates intracellular ROS synthesis within 5min via IL-13Ralpha1-JAK1-STAT6- and IL-13Ralpha2-MEK1/2-ERK1/2-dependent activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-1 (NOX-1). IL-13-induced ROS generation in turn positively regulates phosphorylation of ERK1/2 and STAT6, yielding a feed forward amplification loop. IL-13 also stimulates the stable, long-term gene expression of two other NADPH oxidases, NOX-4 and DUOX-2, which along with constitutive NOX-1, might facilitate elevated, continuous production of ROS in IL-13-activated IEC. The contribution of each signal transduction pathway initiated by IL-13 engagement to such biological functions as wound healing, inflammation, and apoptosis was mapped for representative, responsive genes. Distinct usage patterns were observed, demonstrating not only that IL-13 signal transduction through STAT6, MAPK, and ROS is regulated in both an antagonistic and cyclic fashion, but also that each pathway plays a specific role in modulating the wound healing and anti-apoptotic capabilities of the intestinal epithelium.

Hypertension, diuretics and antihypertensives in relation to bladder cancer

The aim of this study is to investigate the relationships between hypertension, hypertension medication and bladder cancer risk in a population-based case-control study conducted in Los Angeles. Non-Asians between the ages of 25 and 64 years with histologically confirmed bladder cancers diagnosed between 1987 and 1996 were identified through the Los Angeles County Cancer Surveillance Program. A total of 1585 cases and their age-, gender- and race-matched neighborhood controls were included in the analyses. Conditional logistic regression models were used to examine the relationship between history of hypertension, medication use and bladder cancer risk. A history of hypertension was not related to bladder cancer; however, among hypertensive individuals, there was a significant difference in bladder cancer risk related to the use of diuretics or antihypertensive drugs (P for heterogeneity = 0.004). Compared with individuals without hypertension, hypertensive individuals who regularly used diuretics/antihypertensives had a similar risk [odds ratio (OR) 1.06; 95% confidence interval (CI) 0.86-1.30], whereas untreated hypertensive subjects had a 35% reduction in risk (OR: 0.65; 95% CI: 0.48-0.88). A greater reduction in bladder cancer risk was observed among current-smokers (OR: 0.43; 95% CI: 0.27-0.71) and carriers of GSTM1-null (homozygous absence) genotypes (OR: 0.43; 95% CI: 0.22-0.85). Similarly, among smokers with GSTM1-null genotype, levels of 4-aminobiphenyl-hemoglobin adducts were significantly lower among untreated hypertensive individuals (45.7 pg/g Hb) compared with individuals without hypertension (79.8 pg/g Hb) (P = 0.009). In conclusion, untreated hypertension was associated with a reduced risk of bladder cancer.

Resveratrol-induced p53-independent apoptosis of human nasopharyngeal carcinoma cells is correlated with the downregulation of ΔNp63

ΔNp63, the N-terminal truncated isoform of p63, has been found to be overexpressed in several human epithelial cancers, including nasopharyngeal carcinomas (NPCs), suggesting a function in carcinogenesis. Trans-resveratrol (RSV) has been shown to exert proapoptotic activities through a p53-dependent or p53-independent pathway in various cancer cells. However, the effects of RSV on NPC are still unexplored. In this study, we investigated the apoptotic effects of RSV on ΔNp63-overexpressing NPC cell lines. We showed that RSV (12-100 μ) induced dose-dependent growth suppression, cell-cycle arrest in the S phase and caspase-dependent apoptosis in NPC-TW076 and NPC-TW039 cells. The RSV effect was accompanied by the downregulation of ΔNp63 and the upregulation of p53 protein in a dose-dependent manner. By using small-interfering RNA (siRNA) technology, we found that the targeted silencing of ΔNp63 induced apoptosis and sensitized the NPC cells to RSV-induced apoptosis through caspase-3 activation, whereas suppression of p53 by siRNA did not inhibit RSV-induced apoptosis. Furthermore, transfection with p53 siRNA or pretreatment with caspase inhibitors (Z-VAD-fmk or Z-DEVD-fmk) had no influence on the RSV downregulation of ΔNp63. Interestingly, ecoptic expression of ΔNp63 did not significantly block RSV-induced cell death and was also downregulated after RSV treatment. Downregulation of ΔNp63 by RSV was shown to occur at the mRNA transcript and post-translational levels. Importantly, RSV enhanced chemotheraptic drug-induced apoptosis in NPC and two human carcinoma cell lines, HT1376 and Hep3B cells. These results suggested that ΔNp63, but not p53, is a molecular target of RSV-induced apoptosis and the regulation of ΔNp63 expression by RSV may provide a therapeutic effect of RSV in human NPC.

The Roles of Reactive Oxygen Species Produced by Contact Allergens and Irritants in Monocyte-derived Dendritic Cells

BACKGROUND

Although reactive oxygen species (ROS) have been produced in both mouse bone marrow-derived dendritic cells (DCs) and XS-106 DCs by contact sensitizers and irritants in previous studies, the generation of ROS in human monocyte-derived DCs (MoDCs) and their role in contact hypersensitivity (CHS) has yet to be elucidated.

OBJECTIVE

The purpose of this study was to determine whether contact allergens and irritants induce ROS in MoDCs and, if so, to evaluate the role of contact allergen and irritant induced-ROS in MoDCs in CHS.

METHODS

Production of ROS was measured by 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-H(2)DCFDA) assay. Surface CD86 and HLA-DR molecules were detected by flow cytometry. Protein carbonylation was detected by Western blotting.

RESULTS

ROS were produced by contact allergens such as dinitrochlorobenzene (DNCB) and thimerosal and the irritant benzalkonium chloride (BKC). DNCB-induced, but not BKC-induced, ROS increased surface CD86 and HLA-DR molecules on MoDCs and induced protein carbonylation. These changes were reduced in the presence of antioxidant N-acetyl cysteine.

CONCLUSION

Our results suggest that DNCB-induced ROS may be different from those induced by irritant BKC. The DNCB-induced ROS may be associated with the CHS response, because they activate surface molecules on DCs that are important for generating immune reactions.