Therapeutic strategies by modulating oxygen stress in cancer and inflammation

Vitamin K and its analogs: Potential avenues for prostate cancer management

Epidemiological studies have demonstrated a relationship between cancer incidence and dietary habits. Especially intake of certain essential nutrients like vitamins has been shown to be beneficial in experimental studies and some clinical trials. Vitamin K (VK) is an essential nutrient involved in the blood clotting cascade, and there are considerable experimental data demonstrating its potential anticancer activity in several cancer types including prostate cancer. Previous in vitro and in vivo studies have focused mainly on anti-oxidative effects as the underlying anticancer mechanism of VK. However, recent studies reveal that VK inhibits the growth of cancer cells through other mechanisms, including apoptosis, cell cycle arrest, autophagy, and modulation of various transcription factors such as Myc and Fos. In the present review, we focus on the anticancer effect of dietary VK and its analogs on prostate cancer, with an emphasis on the signaling pathways that are activated following exposure to these compounds. This review also highlights the potential of VK and its derivatives as an adjuvant treatment in combination with other vitamins or with chemotherapeutic drugs. Based on our recent results and a review of the existing literature, we present evidence that VK and its derivatives can potentially be explored as cancer therapy, especially for prostate cancer.

Chaetocin induces apoptosis in human melanoma cells through the generation of reactive oxygen species and the intrinsic mitochondrial pathway, and exerts its anti-tumor activity in vivo

Chaetocin is a small-molecule natural product produced by Chaetomium species fungi, and it has a potent anti-proliferative pharmacological activity on various cancer cells. However, the effect of chaetocin on anti-melanoma pharmacological role has not been investigated. Therefore, in this study, we explored the effect of chaetocin on cell proliferation in the human melanoma Sk-Mel-28 and A375 cells and the growth of tumor xenografts in nude mice. The results indicated that chaetocin treatment significantly suppressed cell proliferation and induced apoptosis in the Sk-Mel-28 and A375 cells in a dose- and time-dependent manner. Furthermore, chaetocin treatment resulted in an increased level of cellular reactive oxygen species (ROS), and pre-incubation of cells with N-acetylcysteine (NAC) significantly abrogated chaetocin-induced apoptosis in the melanoma cells. A significant reduction of mitochondrial membrane potential and the release of cytochrome c were observed after chaetocin treatment. Additionally, chaetocin treatment significantly up-regulated the protein levels of Bax, cleaved caspase-9/-3, simultaneously down-regulated the protein levels of Bcl-2, procaspase-9/-3, and activated caspase-9/-3 activity in the melanoma cells. The in vivo data demonstrated that chaetocin treatment significantly inhibited the growth of melanoma tumor xenografts in nude mice, which was closely associated with apoptosis induction, a reduced level of PCNA (proliferating cell nuclear antigen) expression, and activation of capase-9/-3 in tumor xenografts. These are the first data to demonstrate that chaetocin exerts a proapoptotic activity on human melanoma cells through ROS generation and the intrinsic mitochondrial pathway. Therefore, chaetocin might represent an effective candidate for melanoma chemotherapy.

Discovery of monocarbonyl curcumin-BTP hybrids as STAT3 inhibitors for drug-sensitive and drug-resistant breast cancer therapy

Signal transducer and activator of transcription 3 (STAT3) is a well-known antitumor target. Exogenous ROS insult can lead to selective cytotoxicity against cancer cells. A combination of STAT3 inhibition and “oxidation therapy” may be a new strategy to address the multidrug-resistance issue due to their important roles in the survival and drug resistance of cancer cells. Here, a series of novel curcumin-BTP hybrids were designed and evaluated as STAT3 inhibitors with ROS production activity. Compound 6b exerted the best antitumor activity and selectivity for MCF-7 and MCF-7/DOX cells (IC₅₀ = 0.52 μM and 0.40 μM, respectively), while its IC₅₀ value for MCF-10A breast epithelial cells was 7.72 μM. Furthermore, compound 6b suppressed STAT3 phosphorylation, nuclear translocation and DNA-binding activity and the expression of STAT3 specific oncogenes. Increases in the level of IL-6-induced p-STAT3 were also inhibited by 6b without influencing IFN-γ-induced p-STAT1 expression. Additionally, 6b effectively promoted intracellular ROS accumulation, induced cancer cell apoptosis and cell cycle arrest, abolished the colony formation ability of breast cancer cells, and inhibited P-gp expression in MCF-7/DOX cells. Finally, 6b suppressed the growth of implanted human breast cancer in vivo. Our findings highlight that 6b may be a promising therapeutic agent for drug-sensitive and drug-resistant breast cancers.

Compound Copper Chalcogenide Nanocrystals

This review captures the synthesis, assembly, properties, and applications of copper chalcogenide NCs, which have achieved significant research interest in the last decade due to their compositional and structural versatility. The outstanding functional properties of these materials stems from the relationship between their band structure and defect concentration, including charge carrier concentration and electronic conductivity character, which consequently affects their optoelectronic, optical, and plasmonic properties. This, combined with several metastable crystal phases and stoichiometries and the low energy of formation of defects, makes the reproducible synthesis of these materials, with tunable parameters, remarkable. Further to this, the review captures the progress of the hierarchical assembly of these NCs, which bridges the link between their discrete and collective properties. Their ubiquitous application set has cross-cut energy conversion (photovoltaics, photocatalysis, thermoelectrics), energy storage (lithium-ion batteries, hydrogen generation), emissive materials (plasmonics, LEDs, biolabelling), sensors (electrochemical, biochemical), biomedical devices (magnetic resonance imaging, X-ray computer tomography), and medical therapies (photochemothermal therapies, immunotherapy, radiotherapy, and drug delivery). The confluence of advances in the synthesis, assembly, and application of these NCs in the past decade has the potential to significantly impact society, both economically and environmentally.

Diosmin Modulates the NF-kB Signal Transduction Pathways and Downregulation of Various Oxidative Stress Markers in Alloxan-Induced Diabetic Nephropathy

Hyperglycaemia-mediated oxidative stress plays an imperative role in the progression of diabetic nephropathy. NF-kB is an important transcription factor in eukaryotes which regulates a diverse array of cellular process, including inflammation, immunological response, apoptosis, growth and development. Increased expression of NF-kB plays a vital role in the pathogenesis of many inflammatory diseases including diabetic nephropathy. Hence, the present study was designed to explore the nephroprotective nature of diosmin by assessing the various biochemical parameters, markers of oxidative stress and proinflammatory cytokine levels in alloxan-induced diabetic Wistar rats. Type 2 diabetes was induced in Wistar rats by single intraperitoneal injection of alloxan (120 mg/kg body weight). Seventy-two hours after the conformation of diabetes (blood glucose level ≥ 250 mg/dl), the rats were segregated into four groups, each group having six animals. Diabetic rats were treated with diosmin at a dose of 50 mg and 100 mg/kg body weight respectively. After the 28th day of treatment, rats were sacrificed, blood serum, plasma and kidney tissue were collected for various biochemical analysis. Inflammatory cytokine levels were measured through ELISA kit. Diosmin treatment produces significant reduction in the blood glucose and plasma insulin level and increases the body weight when compared with diabetic rats. Elevated level of malondialdehyde (MDA) and decrease levels of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and nitric oxide (NO) were significantly restored after 28 days of diosmin treatment. Diosmin treatment group also restores the normal architecture of the kidney tissue which was confirmed by histopathological examination. Moreover, oral administration of diosmin shows a significant normalization in the level of NF-kB, proving its pivotal role in maintaining renal function. The above ameliorative effects were more pronounced with diosmin at a dose of 100 mg/kg body weight. The above results permit us to conclude that treatment with diosmin halts hyperglycaemia-mediated oxidative stress and decline in pro-inflammatory cytokines and thus has beneficial anti-diabetic activity.

Diverse Applications of Nanomedicine

The design and use of materials in the nanoscale size range for addressing medical and health-related issues continues to receive increasing interest. Research in nanomedicine spans a multitude of areas, including drug delivery, vaccine development, antibacterial, diagnosis and imaging tools, wearable devices, implants, high-throughput screening platforms, etc. using biological, nonbiological, biomimetic, or hybrid materials. Many of these developments are starting to be translated into viable clinical products. Here, we provide an overview of recent developments in nanomedicine and highlight the current challenges and upcoming opportunities for the field and translation to the clinic.

Ayurvedic concept of Shatkriyakala: a traditional knowledge of cancer pathogenesis and therapy

The term Kriyakala refers to the recognition of the stage of a disease's progress, which helps to determine appropriate measure to correct the imbalance in Doshas (biological factors). It is a compound expression, comprised of Kriya and Kala, where Kriya means the choice to treatment (medicine, food and daily-routine) used to improve the disturbance in Doshas, and Kala refers to the stage of progress of a disease. Sushruta, an ancient Indian surgeon, has described the concept of Kriyakala in Varnaprashnadhyaya, an ancient Vedic Sanskrit text, which seeks to explain the incidence of Varnas in terms of Doshic disturbances. Varna, in modern parlance, may be described as an inflammatory process that may lead ulceration and chronic inflammation, promoting all stages of carcinogenesis. Abnormal interactions between Prakriti (genotype) and environmental factors vitiate the Doshas and impair immunity, which can lead to aberrant cell growth and cancer. Moreover, the interaction between vitiated Doshas and weak Dhatus (body tissues) manifests as cancers of a specific organ. Shatkriyakala (six stages of progress of a disease), on the other hand, provides a framework to assess the cancer and its pathogenesis in different stages. According to Ayurvedic concepts, all cancer therapies treat the affected tissues indirectly by eliminating vitiated Doshas, rejuvenating Dhatus and restoring immunity in cancer patients. The present review describes the six stages of Shatkriyakala in detail, with an emphasis on research areas to validate the concept of Shatkriyakala. This traditional knowledge can be utilized with modern technologies to detect predisposition for cancer or diagnose cancer in its early stages.

Avaliação da ingestão de nutrientes antioxidantes pela população brasileira e sua relação com o estado nutricional

RESUMO: Introdução: O estudo dos antioxidantes dietéticos tem ganhado destaque em função da elucidação dos efeitos deletérios do estresse oxidativo ao organismo. Objetivo: Avaliar a ingestão de nutrientes antioxidantes pela população brasileira e sua relação com o estado nutricional. Métodos: Realizou-se um estudo transversal com coleta de dados secundários do consumo alimentar de 33.459 indivíduos de ambos os sexos, de 10 ou mais anos, de todas as regiões do Brasil, a partir dos microdados da Pesquisa de Orçamentos Familiares (2008 - 2009), Inquérito Nacional de Alimentação. Foram analisados os teores das vitaminas E, A e C, zinco, manganês, cobre e selênio de 188 itens alimentares, divididos em 12 grupos, conforme a forma habitual de consumo. As médias de ingestão dos nutrientes antioxidantes de acordo com o estado nutricional foram comparadas por meio do teste t de Bonferroni. Resultados: Foram observados maiores percentuais de ingestão insuficiente para as vitaminas do que para os minerais antioxidantes. Notou-se diferença significativa na ingestão da vitamina E em relação ao estado nutricional, sendo que a ingestão por indivíduos com excesso de peso foi inferior em relação aos com peso adequado. Verificou-se que os indivíduos com baixo peso apresentaram menor ingestão de quase todos os minerais antioxidantes, exceto o cobre, em que a ingestão por indivíduos com baixo peso foi igual à ingestão por aqueles com peso adequado. Conclusão: Elevados percentuais de ingestão insuficiente de nutrientes antioxidantes foram observados na população estudada, especialmente para as vitaminas. Além disso, a ingestão de nutrientes antioxidantes variou conforme o estado nutricional, o sexo e o estágio de vida.

Iron accumulation, glutathione depletion, and lipid peroxidation must occur simultaneously during ferroptosis and are mutually amplifying events

Ferroptosis is a recently discovered form of regulated necrosis that involves iron-dependent lipid peroxidation. How cells die once ferroptosis is triggered remains unclear. Ferroptosis is hypothesized to require three critical events: (1) accumulation of redox-active iron, (2) glutathione depletion, and (3) lipid peroxidation. It is proposed that these three events must unfold simultaneously because stopping any critical event also stops ferroptosis. These events are hypothesized to amplify in severity through positive feedback loops. The cause of death in ferroptosis is therefore the synergistic combination of antioxidant depletion, iron toxicity, and membrane denaturation. The relevance of these feedback loops for cancer and neurodegenerative therapies is discussed.

Nanoparticle-based hyperthermia distinctly impacts production of ROS, expression of Ki-67, TOP2A, and TPX2, and induction of apoptosis in pancreatic cancer

So far, the therapeutic outcome of hyperthermia has shown heterogeneous responses depending on how thermal stress is applied. We studied whether extrinsic heating (EH, hot air) and intrinsic heating (magnetic heating [MH] mediated by nanoparticles) induce distinct effects on pancreatic cancer cells (PANC-1 and BxPC-3 cells). The impact of MH (100 µg magnetic nanoparticles [MNP]/mL; H=23.9 kA/m; f=410 kHz) was always superior to that of EH. The thermal effects were confirmed by the following observations: 1) decreased number of vital cells, 2) altered expression of pro-caspases, and 3) production of reactive oxygen species, and 4) altered mRNA expression of Ki-67, TOP2A, and TPX2. The MH treatment of tumor xenografts significantly (P≤0.05) reduced tumor volumes. This means that different therapeutic outcomes of hyperthermia are related to the different responses cells exert to thermal stress. In particular, intratumoral MH is a valuable tool for the treatment of pancreatic cancers.

Protective effects of molecular hydrogen on steroid-induced osteonecrosis in rabbits via reducing oxidative stress and apoptosis

Background

The objective of this study was to investigate the protective effects of molecular hydrogen, a novel and selective antioxidant, on steroid-induced osteonecrosis (ON) in a rabbit model.

Methods

Sixty rabbits were randomly divided into two groups (model group and hydrogen group). Osteonecrosis was induced according to an established protocol of steroid-induced ON. Rabbits in the hydrogen group were treated with intraperitoneal injections of molecular hydrogen at 10 ml/kg body weight for seven consecutive days. Plasma levels of total cholesterol, triglycerides, soluble thrombomodulin(sTM), glutathione(GSH) and malondialdehyde(MDA) were measured before and after steroid administration. The presence or absence of ON was examined histopathologically. Oxidative injury and vascular injury were assessed in vivo by immunohistochemical staining of 8-hydoxy-2-deoxyguanosine(8-OHdG) and MDA, and ink artery infusion angiography. The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assays were performed to measure apoptosis.

Results

The incidence of steroid-induced ON was significantly lower in hydrogen group (28.6%) than that in model group (68.0%). No statistically differences were observed on the levels of total cholesterol and triglycerides. Oxidative injury, vascular injury and apoptosis were attenuated in the hydrogen group compared with those in the model group in vivo.

Conclusions

These results suggested that molecular hydrogen prevents steroid-induced osteonecrosis in rabbits by suppressing oxidative injury, vascular injury and apoptosis.

Chaetocin reactivates the lytic replication of Epstein-Barr virus from latency via reactive oxygen species

Oxidative stress, regarded as a negative effect of free radicals in vivo, takes place when organisms suffer from harmful stimuli. Some viruses can induce the release of reactive oxygen species (ROS) in infected cells, which may be closely related with their pathogenicity. In this report, chaetocin, a fungal metabolite reported to have antimicrobial and cytostatic activity, was studied for its effect on the activation of latent Epstein-Barr virus (EBV) in B95-8 cells. We found that chaetocin remarkably up-regulated EBV lytic transcription and DNA replication at a low concentration (50 nmol L^-1). The activation of latent EBV was accompanied by an increased cellular ROS level. N-acetyl-L-cysteine (NAC), an ROS inhibitor, suppressed chaetocin-induced EBV activation. Chaetocin had little effect on histone H3K9 methylation, while NAC also significantly reduced H3K9 methylation. These results suggested that chaetocin reactivates latent EBV primarily via ROS pathways.

Flavonoid-surfactant interactions: A detailed physicochemical study

The aim of this article is to study the interactions between flavonoids and surfactants with attention of finding the probable location of flavonoids in micellar media that can be used for controlling their antioxidant behavior. In present study, the micellar and interfacial behavior of twin tailed anionic surfactants viz. sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium bis(2-ethylhexyl)phosphate (NaDEHP) in the presence of two flavonoids, namely quercetin (QUE) and kaempferol (KFL) have been studied by surface tension measurements. UV-visible, fluorescence and differential pulse voltammetric (DPV) measurements have been employed to predict the probable location of flavonoids (QUE/KFL) within surfactant (AOT/NaDEHP) aggregates. Dynamic light scattering (DLS) measurements further confirmed the solubilization of QUE/KFL in AOT/NaDEHP aggregates deduced from increased hydrodynamic diameter (Dh) of aggregates in the presence of flavonoids. Both radical scavenging activity (RSA) and degradation rate constant (k) of flavonoids are found to be higher in NaDEHP micelles as compared to AOT micelles.

A novel H2O2responsive supramolecular hydrogel for controllable drug release

We reported a peptide-based supramolecular hydrogel possessing a gel–sol phase transition triggered by H₂O₂.

Leveraging Physiology for Precision Drug Delivery

Physiological characteristics of diseases bring about both challenges and opportunities for targeted drug delivery. Various drug delivery platforms have been devised ranging from macro- to micro- and further into the nanoscopic scale in the past decades. Recently, the favorable physicochemical properties of nanomaterials, including long circulation, robust tissue and cell penetration attract broad interest, leading to extensive studies for therapeutic benefits. Accumulated knowledge about the physiological barriers that affect the in vivo fate of nanomedicine has led to more rational guidelines for tailoring the nanocarriers, such as size, shape, charge, and surface ligands. Meanwhile, progresses in material chemistry and molecular pharmaceutics generate a panel of physiological stimuli-responsive modules that are equipped into the formulations to prepare “smart” drug delivery systems. The capability of harnessing physiological traits of diseased tissues to control the accumulation of or drug release from nanomedicine has further improved the controlled drug release profiles with a precise manner. Successful clinical translation of a few nano-formulations has excited the collaborative efforts from the research community, pharmaceutical industry, and the public towards a promising future of smart drug delivery.

Controlled synthesis of upconverting nanoparticles/CuS yolk–shell nanoparticles for in vitro synergistic photothermal and photodynamic therapy of cancer cells

A chemical solution method involving multistep process has been developed to fabricate UCNPs@CuS yolk–shell nanoparticles for synergistic photothermal and photodynamic therapy of cancer cells.

Modulating Effect of Hypnea musciformis (Red Seaweed) on Lipid Peroxidation, Antioxidants and Biotransforming Enzymes in 7,12-Dimethylbenz (a) Anthracene Induced Mammary Carcinogenesis in Experimental Animals

Background:

Breast cancer is the second most widespread diagnosed cancer and second leading cause of cancer death in women.

Objective:

The present work was carried out to evaluate the chemo preventive potential of Hypnea musciformis (ethanol extract) seaweed on oxidative stress markers, bio transforming enzymes, incidence of tumors, and pathological observation in 7,12-dimethylbenzanthracene (DMBA) exposed experimental mammary carcinogenesis.

Materials and Methods:

Female Sprague–Dawley rats were randomly divided into four groups. Rats in the group 1 served as control. Rats in the group 2 and 3 received a single subcutaneous injection of DMBA (25 mg/kg body weight (b.w)) in the mammary gland to develop mammary carcinoma. In addition, group 3 rats were orally administrated with 200 mg/kg between of H. musciformis along with DMBA injection and group 4 rats received ethanolic extract of H. musciformis every day orally (200 mg/kg b.w) throughout the experimental period of 16 weeks.

Results:

Our results revealed that treatment with H. musciformis ethanolic extract to DMBA treated rats significantly reduced the incidence of tumor and tumor volume as compared to DMBA alone treated rats. Moreover, our results showed imbalance in the activities/levels of lipid peroxidation by products, antioxidant enzymes, and bio transforming phase I and II enzymes in the circulation, liver and mammary tissues of DMBA treated rats which were significantly modulated to near normal on treatment with ethanolic extract of H. musciformis. All these alterations were supported by histochemical findings.

Conclusion:

The results obtained from this study suggest that chemo preventive potential of H. musciformis ethanol extract is probably due to their free radicals quenching effect and modulating potential of bio transforming enzymes during DMBA exposed experimental mammary carcinogenesis.

SUMMARY

DMBA is a source of well-established site specific carcinogen

Hypnea musciformis act as a free radical quencher

Hypnea musciformis has a definite chemo preventive efficacy in experimental rats

H. musciformis is a resource of prooxidant/antioxidant balance and also its anti-proliferative effects

H. musciformis has a detoxificant in the mammary carcinoma.

Abbreviations Used: BRCA1: Breast Cancer Gene 1; BRCA2: Breast Cancer Gene 1; CYP: Cytochrome P450; DMBA: 7,12-Dimethylbenzanthracene; DMSO: Dimethyl sulfoxide; H2O2: Hydrogen peroxides; LPO: Lipid peroxidation; PAH: Polycyclic aromatic hydrocarbon; ROS: Reactive oxygen species; TBARS: Thiobarbituric acid reactive substances; GSSG: Oxidized glutathione.

Lupane-type triterpenes and their anti-cancer activities against most common malignant tumors: A review

In recent times, a great deal of interest has been motivated on plant derived compounds known as nutraceuticals. These compounds exert important beneficial activities that improve people's health status when are consumed regularly, and now they appear as a viable option to explore their possible therapeutic effects against diseases like cancer. Particularly, lupane-type triterpenes have shown great ability to modulate multiple cancer-related signaling pathways and processes, including NF-κB, Wnt/β-catenin, PI3K/Akt, apoptosis, and many other routes related to proliferation or cell death, which are uncontrolled in malignant tumors. These investigations have promoted in vitro and in vivo studies, searching their mechanisms of action; although more research is still needed to prove its potential in human clinical trials. This review focuses on the ability of betulin, betulinic acid and lupeol to show benefits against the most common types of malignant tumors, which are considered a major global threat for public health.

Targeting Cancer Cells using 3-bromopyruvate for Selective Cancer Treatment

Cancer treatment deserves more research efforts despite intensive conventional treatment modalities for many types of malignancies. Metastasis and resistance to chemotherapy and radiotherapy receive a lot of global research efforts. The current advances in cancer biology may improve targeting the critical metabolic differences that distinguish cancer cells from normal cells. Cancer cells are highly glycolytic for energy production, exhibit the Warburg effect, establish aggressive acidic microenvironment, maintain cancer stem cells, exhibit resistance to chemotherapy, have low antioxidant systems but different ΔΨm (delta psi, mitochondrial transmembrane potential), express P-glycoprotein for multidrug resistance, upregulate glucose transporters and monocarboxylate transporters and are under high steady-state reactive oxygen species conditions. Normal cells differ in all these aspects. Lactate produced through the Warburg effect helps cancer metastasis. Targeting glycolysis reactions for energy production in cancer cells seems promising in decreasing the proliferation and metastasis of cancer cells. 3-bromopyruvate makes use of cancer biology in treating cancer cells, cancer stem cells and preventing metastasis in human cancer as discussed in this review. Updated advances are analyzed here, which include research analysis of background, experience, readings in the field of cancer biology, oncology and biochemistry.

The Glutaminase-1 Inhibitor 968 Enhances Dihydroartemisinin-Mediated Antitumor Efficacy in Hepatocellular Carcinoma Cells

Reprogrammed metabolism and redox homeostasis are potential targets of cancer therapy. Our previous study demonstrated that the kidney form of glutaminase (GLS1) is highly expressed in hepatocellular carcinoma (HCC) cells and can be used as a target for effective anticancer therapy. Dihydroartemisinin (DHA) increases intracellular reactive oxygen species (ROS) levels leading to cytotoxicity in cancer cells. However, the heterogeneity of cancer cells often leads to differing responses to oxidative lesions. For instance, cancer cells with high ratio of GSH/GSSG, a critical ROS scavenger, are resistant to ROS-induced cytotoxicity. We postulate that a combinatorial strategy firstly disrupting redox homeostasis followed by DHA might yield a profound antitumor efficacy. In this study, when HCC cells were treated with a GLS1 inhibitor 968, the ROS elimination capacity was significantly reduced in HCC cells, which rendered HCC cells but not normal endothelial cells more sensitive to DHA-mediated cytotoxicity. We further confirmed that this synergistic antitumor efficacy was mediated by excessive ROS generation in HCC cells. NAC, a ROS inhibitor, partly rescued the combinatorial cytotoxic effect of 968 and DHA. Given that GLS1 is a potential antitumor target and DHA has been safely used in clinic, our findings provide new insight into liver cancer therapy targeting glutamine metabolism combined with the ROS generator DHA, which can be readily translated into cancer clinical trials.

Insights into the role of reactive sulfhydryl groups of Carbonic Anhydrase III and VII during oxidative damage

Carbonic anhydrases (CAs) III and VII are two cytosolic isoforms of the α-CA family which catalyze the physiological reaction of carbon dioxide hydration to bicarbonate and proton. Despite these two enzymes share a 49% sequence identity and present a very similar three-dimensional structure, they show profound differences when comparing the specific activity for CO₂ hydration reaction, with CA VII being much more active than CA III. Recently, CA III and CA VII have been proposed to play a new role as scavenger enzymes in cells where oxidative damage occurs. Here, we will examine functional and structural features of these two isoforms giving insights into their newly proposed protective role against oxidative stress.

Self-Assembled Redox Dual-Responsive Prodrug-Nanosystem Formed by Single Thioether-Bridged Paclitaxel-Fatty Acid Conjugate for Cancer Chemotherapy

Chemotherapeutic efficacy can be greatly improved by developing nanoparticulate drug delivery systems (nano-DDS) with high drug loading capacity and smart stimulus-triggered drug release in tumor cells. Herein, we report a novel redox dual-responsive prodrug-nanosystem self-assembled by hydrophobic small-molecule conjugates of paclitaxel (PTX) and oleic acid (OA). Thioether linked conjugates (PTX-S-OA) and dithioether inserted conjugates (PTX-2S-OA) are designed to respond to the redox-heterogeneity in tumor. Dithioether has been reported to show redox dual-responsiveness, but we find that PTX-S-OA exhibits superior redox sensitivity over PTX-2S-OA, achieving more rapid and selective release of free PTX from the prodrug nanoassemblies triggered by redox stimuli. PEGylated PTX-S-OA nanoassemblies, with impressively high drug loading (57.4%), exhibit potent antitumor activity in a human epidermoid carcinoma xenograft. This novel prodrug-nanosystem addresses concerns related to the low drug loading and inefficient drug release from hydrophobic prodrugs of PTX, and provides possibilities for the development of redox dual-sensitive conjugates or polymers for efficient anticancer drug delivery.

Stimuli-Responsive Block Copolymer-Based Assemblies for Cargo Delivery and Theranostic Applications

Although a number of tactics towards the fabrication and biomedical exploration of stimuli-responsive polymeric assemblies being responsive and adaptive to various factors have appeared, the controlled preparation of assemblies with well-defined physicochemical properties and tailor-made functions are still challenges. These responsive polymeric assemblies, which are triggered by stimuli, always exhibited reversible or irreversible changes in chemical structures and physical properties. However, simple drug/polymer nanocomplexes cannot deliver or release drugs into the diseased sites and cells on-demand due to the inevitable biological barriers. Hence, utilizing therapeutic or imaging agents-loaded stimuli-responsive block copolymer assemblies that are responsive to tumor internal microenvironments (pH, redox, enzyme, and temperature, etc.) or external stimuli (light and electromagnetic field, etc.) have emerged to be an important solution to improve therapeutic efficacy and imaging sensitivity through rationally designing as well as self-assembling approaches. In this review, we summarize a portion of recent progress in tumor and intracellular microenvironment responsive block copolymer assemblies and their applications in anticancer drug delivery and triggered release and enhanced imaging sensitivity. The outlook on future developments is also discussed. We hope that this review can stimulate more revolutionary ideas and novel concepts and meet the significant interest to diverse readers.

ROS and Brain Gliomas: An Overview of Potential and Innovative Therapeutic Strategies

Reactive oxygen species (ROS) represent reactive products belonging to the partial reduction of oxygen. It has been reported that ROS are involved in different signaling pathways to control cellular stability. Under normal conditions, the correct function of redox systems leads to the prevention of cell oxidative damage. When ROS exceed the antioxidant defense system, cellular stress occurs. The cellular redox impairment is strictly related to tumorigenesis. Tumor cells, through the generation of hydrogen peroxide, tend to the alteration of cell cycle phases and, finally to cancer progression. In adults, the most common form of primary malignant brain tumors is represented by gliomas. The gliomagenesis is characterized by numerous molecular processes all characterized by an altered production of growth factor receptors. The difficulty to treat brain cancer depends on several biological mechanisms such as failure of drug delivery through the blood-brain barrier, tumor response to chemotherapy, and intrinsic resistance of tumor cells. Understanding the mechanisms of ROS action could allow the formulation of new therapeutic protocols to treat brain gliomas.

The potential utilizations of hydrogen as a promising therapeutic strategy against ocular diseases

Hydrogen, one of the most well-known natural molecules, has been used in numerous medical applications owing to its ability to selectively neutralize cytotoxic reactive oxygen species and ameliorate hazardous inflammations. Hydrogen can exert protective effects on various reactive oxygen species-related diseases, including the transplantation-induced intestinal graft injury, chronic inflammation, ischemia–reperfusion injuries, and so on. Especially in the eye, hydrogen has been used to counteract multiple ocular pathologies in the ophthalmological models. Herein, the ophthalmological utilizations of hydrogen are systematically reviewed and the underlying mechanisms of hydrogen-induced beneficial effects are discussed. It is our hope that the protective effects of hydrogen, as evidenced by these pioneering studies, would enrich our pharmacological knowledge about this natural element and cast light into the discovery of a novel therapeutic strategy against ocular diseases.

Expression of thioredoxin-1 (TXN) and its relation with oxidative DNA damage and treatment outcome in adult AML and ALL: A comparative study

OBJECTIVE

Thioredoxin-1 (TXN) is a key element in the elimination of reactive oxygen species as well as activation of tumor suppressor genes and DNA repair enzymes. Several studies showed that TXN was over expressed in solid tumors and this was correlated to poorer prognosis. However, TXN expression has been insufficiently studied, particularly in newly diagnosed adult acute leukemia.

METHODS

This study was designed to evaluate the gene expression of TXN in acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL) adult patients and to investigate its association with oxidative DNA damage. The expression of TXN was analyzed using quantitative reverse transcriptase-polymerase chain reaction while oxidative DNA damage was evaluated by measuring serum 8-hydroxy-2-deoxyguanosine (8-OHdG) by enzyme-linked immunosorbent assay and strand breaks by the comet assay.

RESULTS

We found that TXN was under expressed in both AML and ALL groups (P < 0.001 for both) as compared to the control group. Also TXN expression level was negatively correlated with serum 8-OHdG and tail moment in both AML (P = 0.042 and 0.047, respectively) and ALL (P < 0.001 and P = 0.02, respectively) while it showed no correlation with treatment outcome in either groups.

DISCUSSION

This study suggests that TXN expression is hindered in adult acute leukemia which augments oxidative DNA damage and hence mutagenesis.

CONCLUSION

This study provides a new insight into the pathogenesis of acute leukemia and suggests TXN as a new screening test for the risk for acute leukemia.

Self-Assembled ROS-Sensitive Polymer-Peptide Therapeutics Incorporating Built-in Reporters for Evaluation of Treatment Efficacy

One of the major challenges in current cancer therapy is to maximize therapeutic effect and evaluate tumor progression under the scheduled treatment protocol. To address these challenges, we synthesized the cytotoxic peptide (KLAKLAK)2 (named KLAK) conjugated amphiphilic poly(β-thioester)s copolymers (H-P-K) composed of reactive oxygen species (ROS) sensitive backbones and hydrophilic polyethylene glycol (PEG) side chains. H-P-K could self-assemble into micelle-like nanoparticles by hydrophobic interaction with copolymer backbones as cores and PEG and KLAK as shells. The assembled polymer-peptide nanoparticles remarkably improved cellular internalization and accumulation of therapeutic KLAK in cells. Compared to free KLAK peptide, the antitumor activity of H-P-K was significantly enhanced up to ∼400 times, suggesting the effectiveness of the nanoscaled polymer-peptide conjugation as biopharmaceuticals. The higher antitumor activity of nanoparticles was attributed to the efficient disruption of mitochondrial membranes and subsequent excessive ROS production in cells. To realize the ROS monitoring and treatment evaluation, we encapsulated squaraine (SQ) dyes as built-in reporters in ROS-sensitive H-P-K micelles. The overgenerated ROS around mitochondria stimulated the swelling of nanoparticles and subsequent release of SQ, which formed H-aggregates and significantly increased the photoacoustic (PA) signal. We believed that this self-assembled polymer-peptide nanotherapeutics incorporating built-in reporters has great potential for high antitumor performance and in situ treatment evaluation.

Effect of patchouli alcohol on the regulation of heat shock-induced oxidative stress in IEC-6 cells

Purpose Patchouli alcohol (PA) is used to treat gastrointestinal dysfunction. The purpose of this study was to ascertain the function of PA in the regulated process of oxidative stress in rat intestinal epithelial cells (IEC-6). Materials and methods Oxidative stress was stimulated by exposing IEC-6 cells to heat shock (42 °C for 3 h). IEC-6 cells in treatment groups were pretreated with various concentrations of PA (10, 40, and 80 ng/mL) for 3 h before heat shock. Results Heat shock caused damage to the morphology of IEC-6 cells, and increased reactive oxygen species (ROS) level and malondialdehyde (MDA) content. Moreover, mRNA and protein expression by target genes related to oxidative stress in heat shock were also altered. Specifically, the mRNA expression by HSP70, HSP90, GSH-px, NRF2 nd HO-1were all increased, and Nrf2 and Keap1 protein expression were increased after heat shock. However, pretreatment with PA weakened the level of damage to the cellular morphology, and decreased the MDA content caused by heat shock, indicating PA had cytoprotective activities. Pretreatment with PA at high dose significantly increased generation of intracellular ROS. Compared with the heat shock group alone, PA pretreatment significantly decreased the mRNA expression by HSP70, HSP90, SOD, CAT, GSH-px, KEAP1 and HO-1. Furthermore, the high dose of PA significantly increased Nrf2 protein expression, while both the intermediate and high dose of PA significantly increased HO-1 protein expression. Conclusion Heat-shock-induced oxidative stress in IEC-6 cells, and PA could alleviate the Nrf2-Keap1 cellular oxidative stress responses.

Nano-Fenton Reactors as a New Class of Oxidative Stress Amplifying Anticancer Therapeutic Agents

Cancer cells, compared to normal cells, are under oxidative stress associated with an elevated level of reactive oxygen species (ROS) and are more vulnerable to oxidative stress induced by ROS generating agents. Thus, manipulation of the ROS level provides a logical approach to kill cancer cells preferentially, without significant toxicity to normal cells, and great efforts have been dedicated to the development of strategies to induce cytotoxic oxidative stress for cancer treatment. Fenton reaction is an important biological reaction in which irons convert hydrogen peroxide (H2O2) to highly toxic hydroxyl radicals that escalate ROS stress. Here, we report Fenton reaction-performing polymer (PolyCAFe) micelles as a new class of ROS-manipulating anticancer therapeutic agents. Amphiphilic PolyCAFe incorporates H2O2-generating benzoyloxycinnamaldehyde and iron-containing compounds in its backbone and self-assembles to form micelles that serve as Nano-Fenton reactors to generate cytotoxic hydroxyl radicals, killing cancer cells preferentially. When intravenously injected, PolyCAFe micelles could accumulate in tumors preferentially to remarkably suppress tumor growth, without toxicity to normal tissues. This study demonstrates the tremendous translatable potential of Nano-Fenton reactors as a new class of anticancer drugs.

Discovery of New Monocarbonyl Ligustrazine-Curcumin Hybrids for Intervention of Drug-Sensitive and Drug-Resistant Lung Cancer

The elevation of oxidative stress preferentially in cancer cells by inhibiting thioredoxin reductase (TrxR) and/or enhancing reactive oxygen species (ROS) production has emerged as an effective strategy for selectively targeting cancer cells. In this study, we designed and synthesized 21 ligustrazine-curcumin hybrids (10a-u). Biological evaluation indicated that the most active compound 10d significantly inhibited the proliferation of drug-sensitive (A549, SPC-A-1, LTEP-G-2) and drug-resistant (A549/DDP) lung cancer cells but had little effect on nontumor lung epithelial-like cells (HBE). Furthermore, 10d suppressed the TrxR/Trx system and promoted intracellular ROS accumulation and cancer cell apoptosis. Additionally, 10d inhibited the NF-κB, AKT, and ERK signaling, P-gp-mediated efflux of rhodamine 123, P-gp ATPase activity, and P-gp expression in A549/DDP cells. Finally, 10d repressed the growth of implanted human drug-resistant lung cancer in mice. Together, 10d acts a novel TrxR inhibitor and may be a promising candidate for intervention of lung cancer.

Ultrasound-Induced Reactive Oxygen Species Mediated Therapy and Imaging Using a Fenton Reaction Activable Polymersome

Ultrasound techniques have been extensively employed for diagnostic purposes. Because of its features of low cost, easy access, and noninvasive real-time imaging, toward clinical practice it is highly anticipated to simply use diagnostic ultrasound to concurrently perform imaging and therapy. We report a H2O2-filled polymersome to display echogenic reflectivity and reactive oxygen species-mediated cancer therapy simply triggered by the microultrasound diagnostic system accompanied by MR imaging. Instead of filling common perfluorocarbons, the encapsulation of H2O2 in H2O2/Fe3O4-PLGA polymersome provides O2 as the echogenic source and (•)OH as the therapeutic element. On exposure to ultrasound, the polymersome can be easily disrupted to yield (•)OH through the Fenton reaction by reaction of H2O2 and Fe3O4. We showed that malignant tumors can be completely removed in a nonthermal process.

Low nanomolar concentrations of Cucurbitacin-I induces G2/M phase arrest and apoptosis by perturbing redox homeostasis in gastric cancer cells in vitro and in vivo

Cucurbitacin-I (Cu-I, also known as Elatericin B or JSI-124) is developed to inhibit constitutive and abnormal activation of STAT3 in many cancers, demonstrating a potent anticancer activity by targeting disruption of STAT3 function. Here, we for the first time systematically studied the underlying molecular mechanisms of Cu-I-induced gastric cancer cell death both in vitro and in vivo. In our study, we show that Cu-I markedly inhibits gastric cancer cell growth by inducing G2/M phase cell cycle arrest and apoptosis at low nanomolar concentrations via a STAT3-independent mechanism. Notably, Cu-I significantly decreases intracellular GSH/GSSG ratio by inhibiting NRF2 pathway to break cellular redox homeostasis, and subsequently induces the expression of GADD45α in a p53-independent manner, and activates JNK/p38 MAPK signaling. Interestingly, Cu-I-induced GADD45α and JNK/p38 MAPK signaling form a positive feedback loop and can be reciprocally regulated by each other. Therefore, the present study provides new insights into the mechanisms of antitumor effects of Cu-I, supporting Cu-I as an attractive therapeutic drug in gastric cancer by modulating the redox balance.

Miltirone exhibits antileukemic activity by ROS-mediated endoplasmic reticulum stress and mitochondrial dysfunction pathways

In this study, we investigated the effects of miltirone in human leukemia cell lines, primary leukemia cells, and nude mice U937 xenograft. Treatment of cells with miltirone resulted in apoptosis, mitochondria membrane potential (MMP) collapses, increase of Bax/Bcl-2 ratio, and cytochrome c release. Miltirone triggered the endoplasmic reticulum (ER) stress identified through several key molecules of the unfolded protein response, including phosphorylated PERK, eIF2a, GRP78, GRP94, and caspase-12. Miltrone treatment also resulted in the release of Ca²⁺ from the ER stores and mitochondrial Ca²⁺ loading in the cells. Further research revealed that miltirone resulted in dose-dependent decrease in complex III activity and elevated reactive oxygen species (ROS) production in these cells. Miltirone-induced apoptosis, dissipation of MMP and ER stress were dramatically blocked by pretreatment with antioxidant N-acetylcysteine (NAC). In contrast, treatment with ER stress inhibitor TUDCA significantly attenuated miltirone-induced ROS and apoptosis in leukemia cells. Moreover, our in vivo findings showed that administration of miltirone markedly inhibited tumor growth and induced apoptosis in U937 xenograft model with low systemic toxicity. Taken together, these findings indicate that miltirone may exert its antileukemic activity by inducing apoptosis through a ROS-dependent destructive cycle involving ER stress and mitochondrial dysfunction.

A holistic view of cancer bioenergetics: mitochondrial function and respiration play fundamental roles in the development and progression of diverse tumors

Since Otto Warburg made the first observation that tumor cells exhibit altered metabolism and bioenergetics in the 1920s, many scientists have tried to further the understanding of tumor bioenergetics. Particularly, in the past decade, the application of the state-of the-art metabolomics and genomics technologies has revealed the remarkable plasticity of tumor metabolism and bioenergetics. Firstly, a wide array of tumor cells have been shown to be able to use not only glucose, but also glutamine for generating cellular energy, reducing power, and metabolic building blocks for biosynthesis. Secondly, many types of cancer cells generate most of their cellular energy via mitochondrial respiration and oxidative phosphorylation. Glutamine is the preferred substrate for oxidative phosphorylation in tumor cells. Thirdly, tumor cells exhibit remarkable versatility in using bioenergetics substrates. Notably, tumor cells can use metabolic substrates donated by stromal cells for cellular energy generation via oxidative phosphorylation. Further, it has been shown that mitochondrial transfer is a critical mechanism for tumor cells with defective mitochondria to restore oxidative phosphorylation. The restoration is necessary for tumor cells to gain tumorigenic and metastatic potential. It is also worth noting that heme is essential for the biogenesis and proper functioning of mitochondrial respiratory chain complexes. Hence, it is not surprising that recent experimental data showed that heme flux and function are elevated in non-small cell lung cancer (NSCLC) cells and that elevated heme function promotes intensified oxygen consumption, thereby fueling tumor cell proliferation and function. Finally, emerging evidence increasingly suggests that clonal evolution and tumor genetic heterogeneity contribute to bioenergetic versatility of tumor cells, as well as tumor recurrence and drug resistance. Although mutations are found only in several metabolic enzymes in tumors, diverse mutations in signaling pathways and networks can cause changes in the expression and activity of metabolic enzymes, which likely enable tumor cells to gain their bioenergetic versatility. A better understanding of tumor bioenergetics should provide a more holistic approach to investigate cancer biology and therapeutics. This review therefore attempts to comprehensively consider and summarize the experimental data supporting our latest view of cancer bioenergetics.

1,4-Dihydropyridine Derivatives: Dihydronicotinamide Analogues-Model Compounds Targeting Oxidative Stress

Many 1,4-dihydropyridines (DHPs) possess redox properties. In this review DHPs are surveyed as protectors against oxidative stress (OS) and related disorders, considering the DHPs as specific group of potential antioxidants with bioprotective capacities. They have several peculiarities related to antioxidant activity (AOA). Several commercially available calcium antagonist, 1,4-DHP drugs, their metabolites, and calcium agonists were shown to express AOA. Synthesis, hydrogen donor properties, AOA, and methods and approaches used to reveal biological activities of various groups of 1,4-DHPs are presented. Examples of DHPs antioxidant activities and protective effects of DHPs against OS induced damage in low density lipoproteins (LDL), mitochondria, microsomes, isolated cells, and cell cultures are highlighted. Comparison of the AOA of different DHPs and other antioxidants is also given. According to the data presented, the DHPs might be considered as bellwether among synthetic compounds targeting OS and potential pharmacological model compounds targeting oxidative stress important for medicinal chemistry.

Efficient free radical generation against cancer cells by low-dose X-ray irradiation with a functional SPC delivery nanosystem

SPC@HMSNs–PAA can provide oxygen, which induce overproduction of radicals to kill cancer cells even under low energy X-ray irradiation.

Xanthine Oxidoreductase-Derived Reactive Species: Physiological and Pathological Effects

Xanthine oxidoreductase (XOR) is the enzyme that catalyzes the oxidation of hypoxanthine to xanthine and xanthine to uric acid and is widely distributed among species. In addition to this housekeeping function, mammalian XOR is a physiological source of superoxide ion, hydrogen peroxide, and nitric oxide, which can function as second messengers in the activation of various pathways. This review intends to address the physiological and pathological roles of XOR-derived oxidant molecules. The cytocidal action of XOR products has been claimed in relation to tissue damage, in particular damage induced by hypoxia and ischemia. Attempts to exploit this activity to eliminate unwanted cells via the construction of conjugates have also been reported. Moreover, different aspects of XOR activity related to phlogosis, endothelial activation, leukocyte activation, and vascular tone regulation, have been taken into consideration. Finally, the positive and negative outcomes concerning cancer pathology have been analyzed because XOR products may induce mutagenesis, cell proliferation, and tumor progression, but they are also associated with apoptosis and cell differentiation. In conclusion, XOR activity generates free radicals and other oxidant reactive species that may result in either harmful or beneficial outcomes.

Damage to dopaminergic neurons is mediated by proliferating cell nuclear antigen through the p53 pathway under conditions of oxidative stress in a cell model of Parkinson's disease

Oxidative stress is widely considered as a central event in the pathogenesis of Parkinson's disease (PD). The mechanisms underlying the oxidative damage-mediated loss of dopaminergic neurons in PD are not yet fully understood. Accumulating evidence has indicated that oxidative DNA damage plays a crucial role in programmed neuronal cell death, and is considered to be at least partly responsible for the degeneration of dopaminergic neurons in PD. This process involves a number of signaling cascades and molecular proteins. Proliferating cell nuclear antigen (PCNA) is a pleiotropic protein affecting a wide range of vital cellular processes, including chromatin remodelling, DNA repair and cell cycle control, by interacting with a number of enzymes and regulatory proteins. In the present study, the exposure of PC12 cells to 1-methyl-4-phenylpyridinium (MPP+) led to the loss of cell viability and decreased the expression levels of PCNA in a dose- and time-dependent manner, indicating that this protein may be involved in the neurotoxic actions of MPP+ in dopaminergic neuronal cells. In addition, a significant upregulation in p53 expression was also observed in this cellular model of PD. p53 is an upstream inducer of PCNA and it has been recognized as a key contributor responsible for dopaminergic neuronal cell death in mouse models of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD. This indicates that MPP+-induced oxidative damage is mediated by the downregulation of PCNA through the p53 pathway in a cellular model of PD. Thus, our results may provide some novel insight into the molecular mechanisms responsible for the development of PD and provide new possible therapeutic targets for the treatment of PD.

Mitochondria-derived reactive oxygen species drive GANT61-induced mesothelioma cell apoptosis

Gli transcription factors of the Hedgehog (Hh) pathway have been reported to be drivers of malignant mesothelioma (MMe) cell survival. The Gli inhibitor GANT61 induces apoptosis in various cancer cell models, and has been associated directly with Gli inhibition. However various chemotherapeutics can induce cell death through generation of reactive oxygen species (ROS) but whether ROS mediates GANT61-induced apoptosis is unknown. In this study human MMe cells were treated with GANT61 and the mechanisms regulating cell death investigated. Exposure of MMe cells to GANT61 led to G1 phase arrest and apoptosis, which involved ROS but not its purported targets, GLI1 or GLI2. GANT61 triggered ROS generation and quenching of ROS protected MMe cells from GANT61-induced apoptosis. Furthermore, we demonstrated that mitochondria are important in mediating GANT61 effects: (1) ROS production and apoptosis were blocked by mitochondrial inhibitor rotenone; (2) GANT61 promoted superoxide formation in mitochondria; and (3) mitochondrial DNA-deficient LO68 cells failed to induce superoxide, and were more resistant to apoptosis induced by GANT61 than wild-type cells. Our data demonstrate for the first time that GANT61 induces apoptosis by promoting mitochondrial superoxide generation independent of Gli inhibition, and highlights the therapeutic potential of mitochondrial ROS-mediated anticancer drugs in MMe.

Augmentation of oxidative stress-induced apoptosis in MCF7 cells by ascorbate-tamoxifen and/or ascorbate-juglone treatments

Since reactive oxygen species (ROS) play diverse roles in cancer, modulating the redox status of cancerous cells seems to be a promising therapeutic approach. Oxidant-targeted therapy appears logical for intervention with the acquired adaptive response to oxidative stress in cancer. In this study, we investigated the cytotoxic effects of juglone (J) and tamoxifen (T) and also the combination of each with ascorbate (A): tamoxifen/ascorbate (TA) and/or juglone/ascorbate (JA) on MCF7 cancerous cells. The results revealed that the growth inhibitory effects of juglone and tamoxifen were each associated with enhanced levels of ROS production and lipid peroxidation. These effects were markedly intensified in tamoxifen/ascorbate and juglone/ascorbate co-treatments. On the other hand, the intracellular anti-oxidant components such as reduced glutathione (GSH), catalase, superoxide dismutase (SOD), and glutathione peroxidase significantly declined in cells subjected to combination treatments compared to that in cells exposed solely to tamoxifen, juglone, and the untreated control cells. In addition, ascorbate association induced more apoptotic and necrotic or necrotic-like cell death than cells treated with each drug alone. These results were further confirmed by comparing the Bax/Bcl2 ratio in combination-treated cells. Additionally, ascorbate was able to potentiate the cytotoxic effects of combination therapy via activation of ROS-responsive factors including Foxo family members.

Acute exposure of ozone induced pulmonary injury and the protective role of vitamin E through the Nrf2 pathway in Balb/c mice

Ozone (O₃) in the lower atmosphere is generally derived from various sources of human activity. It has become a major air pollutant in China and has been shown to adversely affect the health of humans and animals. We undertook a study to ascertain the molecular mechanism of ozone induced lung injury in mice and tried to demonstrate the protective mechanism of vitamin E. In this study, mice were exposed to clean air and three different concentrations of ozone. Oxidative stress (reactive oxygen species and malondialdehyde) and Th cytokines in the lung, serum IgE, as well as histopathological examination and the airway hyper-responsiveness (AHR) test were used to reflect inflammation and damage to the lungs of ozone-exposed mice. We then chose an effective concentration of ozone and combined treatment with vitamin E (VE) to explore the underlying mechanism of ozone-induced lung damage. The results of immunological and inflammatory biomarkers (total-immunoglobulin (Ig) E and Th cytokines) as well as histopathological examination and AHR assessment supported the notion that high doses of ozone (>0.5 ppm) could induce inflammation and lung injury in mice and that this induction was counteracted by concurrent administration of VE. The elimination of oxidative stress, the reduced Th2 responses and Ig production, and the relief of lung damage were proposed to explain the molecular mechanism of ozone induced lung injury. We also showed that VE, an antioxidant that enhanced the expression of Nrf2 and up-regulated the antioxidant genes HO-1 and NQO1, could decrease the levels of oxidative stress and alleviate ozone-induced lung injury.