Iberis amara Extract Induces Intracellular Formation of Reactive Oxygen Species and Inhibits Colon Cancer

Massively increasing global incidences of colorectal cancer require efficient treatment and prevention strategies. Here, we report unexpected anticancerogenic effects of hydroethanolic Iberis amara extract (IAE), which is known as a widely used phytomedical product for treating gastrointestinal complaints. IAE significantly inhibited the proliferation of HT-29 and T84 colon carcinoma cells with an inhibitory concentration (IC₅₀) of 6 and 9 μg/ml, respectively, and further generated inhibitory effects in PC-3 prostate and MCF7 breast cancer cells. Inhibition of proliferation in HT-29 cells was associated with a G2/M phase cell cycle arrest including reduced expression of various regulatory marker proteins. Notably, in HT-29 cells IAE further induced apoptosis by intracellular formation of reactive oxygen species (ROS). Consistent with predictions derived from our in vitro experiments, bidaily oral gavage of 50 mg/kg of IAE over 4 weeks resulted in significant inhibition of tumor growth in a mouse HT-29 tumor xenograft model. Taken together, Iberis amara extracts could become useful alternatives for preventing and treating the progression of colon cancer.     

Spermine Induces Autophagy in Plants: Possible Role of NO and Reactive Oxygen Species

This is the first study to show that polyamine spermine, a low-molecular-weight nitrogen-containing compound, can induce autophagy in plants. This process is accompanied by an increased generation of reactive oxygen species and nitric oxide, which play a signal role and are required for triggering autophagy.     

Reactive Oxygen Species: Beyond Their Reactive Behavior

Cellular homeostasis plays a critical role in how an organism will develop and age. Disruption of this fragile equilibrium is often associated with health degradation and ultimately, death. Reactive oxygen species (ROS) have been closely associated with health decline and neurological disorders, such as Alzheimer’s disease or Parkinson’s disease. ROS were first identified as by-products of the cellular activity, mainly mitochondrial respiration, and their high reactivity is linked to a disruption of macromolecules such as proteins, lipids and DNA. More recent research suggests more complex function of ROS, reaching far beyond the cellular dysfunction. ROS are active actors in most of the signaling cascades involved in cell development, proliferation and survival, constituting important second messengers. In the brain, their impact on neurons and astrocytes has been associated with synaptic plasticity and neuron survival. This review provides an overview of ROS function in cell signaling in the context of aging and degeneration in the brain and guarding the fragile balance between health and disease.

     

Neuronal Cell Death and Reactive Oxygen Species

1. We have investigated the role of reactive oxygen species (ROS) in cell death induced by ischemia or application of the excitatory amino acid agonist, N-methyl-D-aspartate (NMDA) or kainate (KA), in acutely isolated rat cerebellar granule cell neurons, studied by flow cytometry. Various fluorescent dyes were used to monitor intracellular calcium concentration, ROS concentration, membrane potential, and viability in acutely dissociated neurons subjected to ischemia and reoxygenation alone, NMDA or kainate alone, and ischemia and reoxygenation plus NMDA or kainate.2. With ischemia followed by reoxygenation, ROS concentrations rose slightly and there was only a modest increase in cell death after 60 min.3. When NMDA or kainate alone was applied to the cells there was a large increase in ROS and in intracellular calcium concentration but only a small loss of cellular viability. However, when NMDA or kainate was applied during the reoxygenation period there was a large loss of viability, accompanied by membrane depolarization, but the elevations of ROS and intracellular calcium concentration were not greater than seen with the excitatory amino acids alone.4. These observations indicate that other factors beyond ROS and intracellular calcium concentration contribute to cell death in cerebellar granule cell neurons.     

Reactive Oxygen Species Enhance Insulin Sensitivity

Chronic reactive oxygen species (ROS) production by mitochondria may contribute to the development of insulin resistance, a primary feature of type 2 diabetes. In recent years it has become apparent that ROS generation in response to physiological stimuli such as insulin may also facilitate signaling by reversibly oxidizing and inhibiting protein tyrosine phosphatases (PTPs). Here we report that mice lacking one of the key enzymes involved in the elimination of physiological ROS, glutathione peroxidase 1 (Gpx1), were protected from high-fat-diet-induced insulin resistance. The increased insulin sensitivity in Gpx1^−/− mice was attributed to insulin-induced phosphatidylinositol-3-kinase/Akt signaling and glucose uptake in muscle and could be reversed by the antioxidant N-acetylcysteine. Increased insulin signaling correlated with enhanced oxidation of the PTP family member PTEN, which terminates signals generated by phosphatidylinositol-3-kinase. These studies provide causal evidence for the enhancement of insulin signaling by ROS in vivo.     

气孔运动中的活性氧信号

大量研究证明活性氧(ROS)在气孔运动中起信号分子的作用。保卫细胞中ROS的产生依赖于特定的酶,其中NADPH氧化酶组分RBOH已得到深入研究,并已证实其参与生物与非生物胁迫反应。植物激素包括脱落酸(ABA)、水杨酸(SA)、乙烯、生长素及细胞分裂素等,它们均通过ROS的介导来调控气孔运动。生物胁迫(如毒性细菌和真菌)也会调控气孔运动。ROS参与这些调控过程。保卫细胞中存在多层次对ROS产生及其作用的调节,抗氧化活性物质和ROS敏感蛋白(如蛋白激酶和磷酸酶)均可传递ROS信号并调节气孔运动。ROS对离子通道调节的证据也越来越多。保卫细胞由于可通过ROS整合复杂的信号途径,已成为研究植物ROS信号转导过程的良好模式系统。     

Dopamine Induces Ca2+ Signaling in Astrocytes through Reactive Oxygen Species Generated by Monoamine Oxidase

Dopamine is a neurotransmitter that plays a major role in a variety of brain functions, as well as in disorders such as Parkinson disease and schizophrenia. In cultured astrocytes, we have found that dopamine induces sporadic cytoplasmic calcium ([Ca²⁺]_c) signals. Importantly, we show that the dopamine-induced calcium signaling is receptor-independent in midbrain, cortical, and hippocampal astrocytes. We demonstrate that the calcium signal is initiated by the metabolism of dopamine by monoamine oxidase, which produces reactive oxygen species and induces lipid peroxidation. This stimulates the activation of phospholipase C and subsequent release of calcium from the endoplasmic reticulum via the inositol 1,4,5-trisphosphate receptor mechanism. These findings have major implications on the function of astrocytes that are exposed to dopamine and may contribute to understanding the physiological role of dopamine.     

NADPH Oxidase-Dependent Production of Reactive Oxygen Species Induces Endoplasmatic Reticulum Stress in Neutrophil-Like HL60 Cells

Reactive oxygen species (ROS) primarily produced via NADPH oxidase play an important role for killing microorganisms in neutrophils. In this study we examined if ROS production in Human promyelocytic leukemia cells (HL60) differentiated into neutrophil-like cells (dHL60) induces ER stress and activates the unfolded protein response (UPR). To cause ROS production cells were treated with PMA or by chronic hyperglycemia. Chronic hyperglycemia failed to induce ROS production and did not cause activation of the UPR in dHL60 cells. PMA, a pharmacologic NADPH oxidase activator, induced ER stress in dHL60 cells as monitored by IRE-1 and PERK pathway activation, and this was independent of calcium signaling. The NADPH oxidase inhibitor, DPI, abolished both ROS production and UPR activation. These results show that ROS produced by NADPH oxidase induces ER stress and suggests a close association between the redox state of the cell and the activation of the UPR in neutrophil-like HL60 cells.     

ROS在植物激素信号转导中的作用（综述）

植物能感受外界环境信息的刺激,并通过复杂的信号转导体系调节植物特定基因的表达,引起相应的生理生化反应,以适应不断变化的环境条件.研究表明,活性氧作为第二信使参与了植物激素信号转导,本文对其在植物激素信号转导中的作用进行综述.     

Reactive Oxygen Species and Human Inflammatory Periodontal Diseases

Reactive oxygen species (ROS) have emerged as important signaling molecules in the regulation of various cellular processes. They can be generated by the mitochondrial electron transport chain in mitochondria and activation of polymorphonuclear leukocytes (PMN) during inflammatory conditions. Excessive generation of ROS may result in attack of and damage to most intracellular and extracellular components in a living organism. Moreover, ROS can directly induce and/or regulate apoptotic and necrotic cell death. Periodontal pathologies are inflammatory and degenerative diseases. Several forms of periodontal diseases are associated with activated PMN. Damage of tissues in inflammatory periodontal pathologies can be mediated by ROS resulting from the physiological activity of PMN during the phagocytosis of periodontopathic bacteria.__________Translated from Biokhimiya, Vol. 70, No. 6, 2005, pp. 751–761.Original Russian Text Copyright © 2005 by Canakci, Cicek, Canakci.     

活性氧簇对蛋白尿的影响

蛋白尿不仅反映肾小球损伤,而且是一个独立的导致肾脏病变进展的主要因素,任何能够使蛋白尿减少的治疗干预都有利于减慢肾脏疾病的进展,遗传性蛋白尿性肾病是由于基因突变所致,获得性肾病大量蛋白尿成因目前尚未阐明。免疫异常,炎症介质及氧化应激反应均可导致肾损伤。氧自由基是肾损伤的主要介质,它作为强氧化剂是造成蛋白尿的重要原因之一。活性氧分子(ROS)可以通过降解肾小球乙酰肝素硫酸盐、肾小球基底膜Ⅳ型胶原富含赖氨酸的NCl区域发生交联、损伤足细胞破坏肾小球滤过屏障及与其他活性因子作用增强血清蛋白的渗透性等作用,造成蛋白尿。本文就近年来人们对活性氧造成蛋白尿的机制的研究做一综述,便于帮助医务工作者更好的了解和治疗蛋白尿性肾病。     

植物中活性氧的检测方法

主要对超氧阴离子自由基(O2-·)、过氧化氢(H2O2)等活性氧的检测方法,包括化学发光法、分光光度法、荧光染色法,EPR波谱学方法、DAB组织染色法和电子显微技术检测法等进行了综述,并简单介绍了最近发展起来的一些新技术。     

Mobile Phone Radiation Induces Reactive Oxygen Species Production and DNA Damage in Human Spermatozoa In Vitro

Background

In recent times there has been some controversy over the impact of electromagnetic radiation on human health. The significance of mobile phone radiation on male reproduction is a key element of this debate since several studies have suggested a relationship between mobile phone use and semen quality. The potential mechanisms involved have not been established, however, human spermatozoa are known to be particularly vulnerable to oxidative stress by virtue of the abundant availability of substrates for free radical attack and the lack of cytoplasmic space to accommodate antioxidant enzymes. Moreover, the induction of oxidative stress in these cells not only perturbs their capacity for fertilization but also contributes to sperm DNA damage. The latter has, in turn, been linked with poor fertility, an increased incidence of miscarriage and morbidity in the offspring, including childhood cancer. In light of these associations, we have analyzed the influence of RF-EMR on the cell biology of human spermatozoa in vitro.

Principal Findings

Purified human spermatozoa were exposed to radio-frequency electromagnetic radiation (RF-EMR) tuned to 1.8 GHz and covering a range of specific absorption rates (SAR) from 0.4 W/kg to 27.5 W/kg. In step with increasing SAR, motility and vitality were significantly reduced after RF-EMR exposure, while the mitochondrial generation of reactive oxygen species and DNA fragmentation were significantly elevated (P<0.001). Furthermore, we also observed highly significant relationships between SAR, the oxidative DNA damage bio-marker, 8-OH-dG, and DNA fragmentation after RF-EMR exposure.

Conclusions

RF-EMR in both the power density and frequency range of mobile phones enhances mitochondrial reactive oxygen species generation by human spermatozoa, decreasing the motility and vitality of these cells while stimulating DNA base adduct formation and, ultimately DNA fragmentation. These findings have clear implications for the safety of extensive mobile phone use by males of reproductive age, potentially affecting both their fertility and the health and wellbeing of their offspring.     

Reactive Oxygen Species Tune Root Tropic Responses

The default growth pattern of primary roots of land plants is directed by gravity. However, roots possess the ability to sense and respond directionally to other chemical and physical stimuli, separately and in combination. Therefore, these root tropic responses must be antagonistic to gravitropism. The role of reactive oxygen species (ROS) in gravitropism of maize and Arabidopsis (Arabidopsis thaliana) roots has been previously described. However, which cellular signals underlie the integration of the different environmental stimuli, which lead to an appropriate root tropic response, is currently unknown. In gravity-responding roots, we observed, by applying the ROS-sensitive fluorescent dye dihydrorhodamine-123 and confocal microscopy, a transient asymmetric ROS distribution, higher at the concave side of the root. The asymmetry, detected at the distal elongation zone, was built in the first 2 h of the gravitropic response and dissipated after another 2 h. In contrast, hydrotropically responding roots show no transient asymmetric distribution of ROS. Decreasing ROS levels by applying the antioxidant ascorbate, or the ROS-generation inhibitor diphenylene iodonium attenuated gravitropism while enhancing hydrotropism. Arabidopsis mutants deficient in Ascorbate Peroxidase 1 showed attenuated hydrotropic root bending. Mutants of the root-expressed NADPH oxidase RBOH C, but not rbohD, showed enhanced hydrotropism and less ROS in their roots apices (tested in tissue extracts with Amplex Red). Finally, hydrostimulation prior to gravistimulation attenuated the gravistimulated asymmetric ROS and auxin signals that are required for gravity-directed curvature. We suggest that ROS, presumably H₂O₂, function in tuning root tropic responses by promoting gravitropism and negatively regulating hydrotropism.Plants evolved the ability to sense and respond to various environmental stimuli in an integrated fashion. Due to their sessile nature, they respond to directional stimuli such as light, gravity, touch, and moisture by directional organ growth (curvature), a phenomenon termed tropism. Experiments on coleoptiles conducted by Darwin in the 1880s revealed that in phototropism, the light stimulus is perceived by the tip, from which a signal is transmitted to the growing part (Darwin and Darwin, 1880). Darwin postulated that in a similar manner, the root tip perceives stimuli from the environment, including gravity and moisture, processes them, and directs the growth movement, acting like “the brain of one of the lower animals” (Darwin and Darwin, 1880). The transmitted signal in phototropism and gravitropism was later found to be a phytohormone, and its redistribution on opposite sides of the root or shoot was hypothesized to promote differential growth and bending of the organ (Went, 1926; Cholodny, 1927). Over the years, the phytohormone was characterized as indole-3-acetic acid (IAA, auxin; Kögl et al., 1934; Thimann, 1935), and the ‘Cholodny-Went’ theory was demonstrated for gravitropism and phototropism (Rashotte et al., 2000; Friml et al., 2002). In addition to auxin, second messengers such as Ca²⁺, pH oscillations, reactive oxygen species (ROS) and abscisic acid (ABA) were shown to play an essential role in gravitropism (Young and Evans, 1994; Fasano et al., 2001; Joo et al., 2001; Ponce et al., 2008). Auxin was shown to induce ROS accumulation during root gravitropism, where the gravitropic bending is ROS dependent (Joo et al., 2001; Peer et al., 2013).ROS such as superoxide and hydrogen peroxide were initially considered toxic byproducts of aerobic respiration but currently are known also for their essential role in myriad cellular and physiological processes in animals and plants (Mittler et al., 2011). ROS and antioxidants are essential components of plant cell growth (Foreman et al., 2003), cell cycle control, and shoot apical meristem maintenance (Schippers et al., 2016) and play a crucial role in protein modification and cellular redox homeostasis (Foyer and Noctor, 2005). ROS function as signal molecules by mediating both biotic- (Sagi and Fluhr, 2006; Miller et al., 2009) and abiotic- (Kwak et al., 2003; Sharma and Dietz, 2009) stress responses. Joo et al. (2001) reported a transient increase in intracellular ROS concentrations early in the gravitropic response, at the concave side of maize roots, where auxin concentrations are higher. Indeed, this asymmetric ROS distribution is required for gravitropic bending, since maize roots treated with antioxidants, which act as ROS scavengers, showed reduced gravitropic root bending (Joo et al., 2001). The link between auxin and ROS production was later shown to involve the activation of NADPH oxidase, a major membrane-bound ROS generator, via a PI3K-dependent pathway (Brightman et al., 1988; Joo et al., 2005; Peer et al., 2013). Peer et al. (2013) suggested that in gravitropism, ROS buffer auxin signaling by oxidizing the active auxin IAA to the nonactive and nontransported form, oxIAA.Gravitropic-oriented growth is the default growth program of the plant, with shoots growing upwards and roots downward. However, upon exposure to specific external stimuli, the plant overcomes its gravitropic growth program and bends toward or away from the source of the stimulus. For example, as roots respond to physical obstacles or water deficiency. The ability of roots to direct their growth toward environments of higher water potential was described by Darwin and even earlier and was later defined as hydrotropism (Von Sachs, 1887; Jaffe et al., 1985; Eapen et al., 2005).In Arabidopsis (Arabidopsis thaliana), wild-type seedlings respond to moisture gradients (hydrostimulation) by bending their primary roots toward higher water potential. Upon hydrostimulation, amyloplasts, the starch-containing plastids in root-cap columella cells, which function as part of the gravity sensing system, are degraded within hours and recover upon water replenishment (Takahashi et al., 2003; Ponce et al., 2008; Nakayama et al., 2012). Moreover, mutants with a reduced response to gravity (pgm1) and to auxin (axr1 and axr2) exhibit higher responsiveness to hydrostimulation, manifested as accelerated bending compared to wild-type roots (Takahashi et al., 2002, 2003). Recently, we have shown that hydrotropic root bending does not require auxin redistribution and is accelerated in the presence of auxin polar transport inhibitors and auxin-signaling antagonists (Shkolnik et al., 2016). These results reflect the competition, or interference, between root gravitropism and hydrotropism (Takahashi et al., 2009). However, which cellular signals participate in the integration of the different environmental stimuli that direct root tropic curvature is still poorly understood. Here we sought to assess the potential role of ROS in regulating hydrotropism and gravitropism in Arabidopsis roots.