Cysteine (C)-X-C Receptor 4 Regulates NADPH Oxidase-2 During Oxidative Stress in Prostate Cancer Cells

Alpha pyrrolidinovalerophenone (α-PVP) administration impairs spatial learning and memory in rats through brain mitochondrial dysfunction

Novel psychoactive substances (NPS) consumption has increased in recent years, thus NPS-induced cognitive decline is a current source of concern. Alpha-pyrrolidinovalerophenone (α-PVP), as a member of NPS, is consumed throughout regions like Washington, D.C., Eastern Europe, and Central Asia. Mitochondrial dysfunction plays an essential role in NPS-induced cognitive impairment. Meanwhile, no investigations have been conducted regarding the α-PVP impact on spatial learning/memory and associated mechanisms. Consequently, our study investigated the α-PVP effect on spatial learning/memory and brain mitochondrial function. Wistar rats received different α-PVP doses (5, 10, and 20 mg/kg) intraperitoneally for 10 sequential days; 24 h after the last dose, spatial learning/memory was evaluated by the Morris Water Maze (MWM). Furthermore, brain mitochondrial protein yield and function variables (Mitochondrial swelling, succinate dehydrogenase (SDH) activity, lipid peroxidation, Mitochondrial Membrane Potential (MMP), Reactive oxygen species (ROS) level, brain ADP/ATP proportion, cytochrome c release, Mitochondrial Outer Membrane (MOM) damage) were examined. α-PVP higher dose (20 mg/kg) significantly impaired spatial learning/memory, mitochondrial protein yield, and brain mitochondrial function (caused reduced SDH activity, increased mitochondrial swelling, elevated ROS generation, increased lipid peroxidation, collapsed MMP, increased cytochrome c release, and brain ADP/ATP proportion, and MOM damage). Moreover, the lower dose of α-PVP (5 mg/kg) did not alter spatial learning/memory and brain mitochondrial function. These findings provide the first evidence regarding impaired spatial learning and memory following repeated administration of α-PVP and the possible role of brain mitochondrial dysfunction in these cognitive impairments.

Protective Effect of CXCR4 Antagonist DBPR807 against Ischemia-Reperfusion Injury in a Rat and Porcine Model of Myocardial Infarction: Potential Adjunctive Therapy for Percutaneous Coronary Intervention

CXCR4 antagonists have been claimed to reduce mortality after myocardial infarction in myocardial infarction (MI) animals, presumably due to suppressing inflammatory responses caused by myocardial ischemia-reperfusion injury, thus, subsequently facilitating tissue repair and cardiac function recovery. This study aims to determine whether a newly designed CXCR4 antagonist DBPR807 could exert better vascular-protective effects than other clinical counterparts (e.g., AMD3100) to alleviate cardiac damage further exacerbated by reperfusion. Consequently, we find that instead of traditional continuous treatment or multiple-dose treatment at different intervals of time, a single-dose treatment of DBPR807 before reperfusion in MI animals could attenuate inflammation via protecting oxidative stress damage and preserve vascular/capillary density and integrity via mobilizing endothelial progenitor cells, leading to a desirable fibrosis reduction and recovery of cardiac function, as evaluated with the LVEF (left ventricular ejection fraction) in infarcted hearts in rats and mini-pigs, respectively. Thus, it is highly suggested that CXCR4 antagonists should be given at a single high dose prior to reperfusion to provide the maximal cardiac functional improvement. Based on its favorable efficacy and safety profiles indicated in tested animals, DBPR807 has a great potential to serve as an adjunctive medicine for percutaneous coronary intervention (PCI) therapies in acute MI patients.

The Antileukemic and Anti-Prostatic Effect of Aeroplysinin-1 Is Mediated through ROS-Induced Apoptosis via NOX Activation and Inhibition of HIF-1a Activity

Aeroplysinin-1 is a brominated isoxazoline alkaloid that has exhibited a potent antitumor cell effect in previous reports. We evaluated the cytotoxicity of aeroplysinin-1 against leukemia and prostate cancer cells in vitro. This marine alkaloid inhibited the cell proliferation of leukemia Molt-4, K562 cells, and prostate cancer cells Du145 and PC-3 with IC₅₀ values of 0.12 ± 0.002, 0.54 ± 0.085, 0.58 ± 0.109 and 0.33 ± 0.042 µM, respectively, as shown by the MTT assay. Furthermore, in the non-malignant cells, CCD966SK and NR8383, its IC₅₀ values were 1.54 ± 0.138 and 6.77 ± 0.190 μM, respectively. In a cell-free system, the thermal shift assay and Western blot assay verified the binding affinity of aeroplysinin-1 to Hsp90 and Topo IIα, which inhibited their activity. Flow cytometry analysis showed that the cytotoxic effect of aeroplysinin-1 is mediated through mitochondria-dependent apoptosis induced by reactive oxygen species (ROS). ROS interrupted the cellular oxidative balance by activating NOX and inhibiting HIF-1α and HO-1 expression. Pretreatment with N-acetylcysteine (NAC) reduced Apl-1-induced mitochondria-dependent apoptosis and preserved the expression of NOX, HO-1, and HIF-1a. Our findings indicated that aeroplysinin-1 targeted leukemia and prostate cancer cells through multiple pathways, suggesting its potential application as an anti-leukemia and prostate cancer drug lead.

Oxidative Stress and Redox-Dependent Signaling in Prostate Cancer

Tumor emergence and progression is complicated by the dual role of reactive oxygen species (ROS). Low concentrations of ROS are essential for many intracellular metabolic processes and cell proliferation, while excessive ROS generation disrupts the mechanisms of cancer suppression, leading to the cell damage and death. A long-term imbalance in the ROS/antioxidant ratio and upregulation of the ROS generation due to the reduced efficacy of the antioxidant defense system cause chronic oxidative stress resulting in the damage of proteins, lipid, and DNA molecules and cancer development. Numerous data demonstrate that prostate cancer (the most common cancer in males) is associated with the development of oxidative stress. However, the reasons for the emergence of prostate cancer, as well as changes in the redox signaling and cellular redox homeostasis in this disease, are still poorly understood. The review examines the role of prooxidant and antioxidant enzyme systems, the imbalance in their activity leading to the oxidative stress development, changes in the key components of redox signaling, and the role of microRNAs in the modulation of redox status of cancer cells in prostate cancer.

Serum deprivation initiates adaptation and survival to oxidative stress in prostate cancer cells

Inadequate nutrient intake leads to oxidative stress disrupting homeostasis, activating signaling, and altering metabolism. Oxidative stress serves as a hallmark in developing prostate lesions, and an aggressive cancer phenotype activating mechanisms allowing cancer cells to adapt and survive. It is unclear how adaptation and survival are facilitated; however, literature across several organisms demonstrates that a reversible cellular growth arrest and the transcription factor, nuclear factor-kappaB (NF-κB), contribute to cancer cell survival and therapeutic resistance under oxidative stress. We examined adaptability and survival to oxidative stress following nutrient deprivation in three prostate cancer models displaying varying degrees of tumorigenicity. We observed that reducing serum (starved) induced reactive oxygen species which provided an early oxidative stress environment and allowed cells to confer adaptability to increased oxidative stress (H₂O₂). Measurement of cell viability demonstrated a low death profile in stressed cells (starved + H₂O₂), while cell proliferation was stagnant. Quantitative measurement of apoptosis showed no significant cell death in stressed cells suggesting an adaptive mechanism to tolerate oxidative stress. Stressed cells also presented a quiescent phenotype, correlating with NF-κB nuclear translocation, suggesting a mechanism of tolerance. Our data suggests that nutrient deprivation primes prostate cancer cells for adaptability to oxidative stress and/or a general survival mechanism to anti-tumorigenic agents.

The role of reactive oxygen species in angiogenesis and preventing tissue injury after brain ischemia

Oxidative stress, which is defined as an imbalance between proxidant and antioxidant systems, is the essential mechanism involving in the ischemic process. During the early stage of brain ischemia, reactive oxygen species (ROS) are increased. Increased ROS are thought of a consequence of brain ischemia and exacerbating disease due to inducing cell death, apoptosis and senescence by oxidative stress. During brain tissue repair, ROS are act as signaling molecules and may be benefical for regulating angiogenesis and preventing tissue injury. New blood vessel formation is essentially required for rescuing tissue from brain ischemia. In ischemic conditions, ROS promotes angiogenesis, either directly or via the generation of active oxidation products. ROS-induced angiogenesis involves several signaling pathways. This paper reviewed current understanding of the role of ROS as a mediator and modulator of angiogenesis in brain ischemia.

Inhibition of NADPH oxidase 2 induces apoptosis in osteosarcoma: The role of reactive oxygen species in cell proliferation

Osteosarcomas (OS) are aggressive tumors that are characterized by dysregulated growth and resistance to apoptosis. Reactive oxygen species (ROS) are thought to be important signal transduction molecules in the regulation of cell growth. ROS-generating nicotinamide adenine dinucleotide phosphate oxidase (NOX) family enzymes have previously been suggested to be involved in neoplastic proliferation. To examine whether NOX-mediated generation of intracellular ROS confers anti-apoptotic activity, and thus a growth advantage, the current study first analyzed the mRNA expression of NOX family members by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in five human OS cell lines. RT-PCR analysis revealed that NOX2 and NOX4 mRNAs were expressed in all the OS cell lines examined, whereas little or no NOX1 and NOX3 mRNAs were detected. By RT-qPCR, NOX2 mRNA expression levels were demonstrated to be higher than NOX4 mRNA expression levels. The viability of OS cells decreased in a dose-dependent manner with treatment of diphenylene iodonium (DPI), an inhibitor of flavoprotein-dependent oxidase. DPI treatment was observed to reduce intracellular ROS levels by ~50%, and increase the frequency of apoptosis by 30%. Notably, small interfering RNAs (siRNAs) targeting NOX2 significantly suppressed ROS generation; ROS depletion by DPI or NOX2 siRNAs induced apoptosis in OS cells. Together, the results of the present study indicate that NOX2-mediated ROS generation promotes cell survival and ROS depletion leads to apoptosis, thus highlighting the NOX2-ROS signaling pathway as a potential therapeutic target for OS treatment.

Oxidative stress and prostatic diseases

Prostatic diseases are a common health problem among males in Western countries, and include chronic prostatic diseases, which have an unclear pathogenesis and few treatment options. In vitro and in vivo studies describe oxidative stress as a major pathway involved in the occurrence of benign prostatic hyperplasia, prostatic cancer and chronic prostatitis. Thus, the oxidative stress cascade is a potential target for the treatment of prostatic diseases. This paper presents a systematic review of the available data concerning the association between oxidative stress and the most common chronic prostatic diseases, and describes the available treatment options that act upon this pathway.

Oxidative stress in prostate hyperplasia and carcinogenesis

Prostatic hyperplasia (PH) is a common urologic disease that affects mostly elderly men. PH can be classified as benign prostatic hyperplasia (BPH), or prostate cancer (PCa) based on its severity. Oxidative stress (OS) is known to influence the activities of inflammatory mediators and other cellular processes involved in the initiation, promotion and progression of human neoplasms including prostate cancer. Scientific evidence also suggests that micronutrient supplementation may restore the antioxidant status and hence improve the clinical outcomes for patients with BPH and PCa. This review highlights the recent studies on prostate hyperplasia and carcinogenesis, and examines the role of OS on the molecular pathology of prostate cancer progression and treatment.

A NOX2/Egr-1/Fyn pathway delineates new targets for TKI-resistant malignancies

Tyrosine kinase inhibitors (TKI) have improved CML response rates, and some are effective against resistance-promoting point mutations in BCR-ABL1. However, in the absence of point mutations, resistance still occurs. Here, we identify a novel pathway mediating resistance which connects p47phox, the organizer subunit of NADPH oxidase-2 (NOX2), with early growth response-1 (Egr-1) and the Src family kinase Fyn. We found up-regulation of p47phox, Egr-1, and Fyn mRNA and protein using paired isogenic CML cell lines and mined data. Isolation of CD34⁺ cells and tissue microarray staining from blast crisis CML patients confirmed in vivo over-expression of components of this pathway. Knockdown studies revealed that p47phox modulated reactive oxygen species and Egr-1 expression, which, in turn, controlled Fyn expression. Interestingly, Fyn knockdown sensitized TKI-resistant cells to dasatinib, a dual BCR-ABL1/Src inhibitor. Egr-1 knockdown had similar effects, indicating the utility of targeting Fyn expression over activation. Pointedly, p47phox knockdown also restored TKI-sensitivity, indicating that targeting the NOX2 complex can overcome resistance. The NOX2/Egr-1/Fyn pathway was also conserved within TKI-resistant EGFRΔIII-expressing glioblastoma and patient-derived glioblastoma stem cells. Thus, our findings suggest that targeting the NOX2/Egr-1/Fyn pathway may have clinical implications within multiple cancer types; particularly where efficacy of TKI is compromised.

Oxidative stress in benign prostatic hyperplasia: a systematic review

BACKGROUND

Several parameters including inflammatory mediators, hormones, dietary factors, inflammatory genes, and oxidative stress (OS) have been considered to play a role in the development of benign prostatic hyperplasia (BPH). Prostate tissue damage and OS may lead to compensatory cellular proliferation with resulting hyperplastic growth.

METHODS

We searched MEDLINE for articles in English published up to March 2014 using the key words 'oxidative stress', 'antioxidants' and 'benign prostatic hyperplasia'.

RESULTS

Prostatic inflammation can cause the generation of free radicals. The extent of oxidative damage can be exacerbated by a decreased efficiency of antioxidant defense mechanisms. The balance between OS and the antioxidant component also has a role in developing prostate disease. Several works show the role of oxidant products and of depletion of antioxidant substances in BPH patients. It is accepted that free radicals play a role in carcinogenesis and that BPH should be considered a premalignant condition which may evolve into prostate cancer. High OS parameters and low antioxidant activity are more prominent in prostate cancer patients compared with BPH and controls.

CONCLUSIONS

Further studies are needed to clarify the potential role of antioxidants in BPH also in view of preventing the progression to prostate cancer.

The redox biology network in cancer pathophysiology and therapeutics

The review pinpoints operational concepts related to the redox biology network applied to the pathophysiology and therapeutics of solid tumors. A sophisticated network of intrinsic and extrinsic cues, integrated in the tumor niche, drives tumorigenesis and tumor progression. Critical mutations and distorted redox signaling pathways orchestrate pathologic events inside cancer cells, resulting in resistance to stress and death signals, aberrant proliferation and efficient repair mechanisms. Additionally, the complex inter-cellular crosstalk within the tumor niche, mediated by cytokines, redox-sensitive danger signals (HMGB1) and exosomes, under the pressure of multiple stresses (oxidative, inflammatory, metabolic), greatly contributes to the malignant phenotype. The tumor-associated inflammatory stress and its suppressive action on the anti-tumor immune response are highlighted. We further emphasize that ROS may act either as supporter or enemy of cancer cells, depending on the context. Oxidative stress-based therapies, such as radiotherapy and photodynamic therapy, take advantage of the cytotoxic face of ROS for killing tumor cells by a non-physiologically sudden, localized and intense oxidative burst. The type of tumor cell death elicited by these therapies is discussed. Therapy outcome depends on the differential sensitivity to oxidative stress of particular tumor cells, such as cancer stem cells, and therefore co-therapies that transiently down-regulate their intrinsic antioxidant system hold great promise. We draw attention on the consequences of the damage signals delivered by oxidative stress-injured cells to neighboring and distant cells, and emphasize the benefits of therapeutically triggered immunologic cell death in metastatic cancer. An integrative approach should be applied when designing therapeutic strategies in cancer, taking into consideration the mutational, metabolic, inflammatory and oxidative status of tumor cells, cellular heterogeneity and the hypoxia map in the tumor niche, along with the adjoining and systemic effects of oxidative stress-based therapies.

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Critical point mutations and distorted redox-sensitive signaling pathways underlie the tumorigenic phenotype.

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Inter-cellular crosstalk under stress conditions in the tumor niche drives the behavior of tumor cells.

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ROS may act as either as supporter or enemy of tumor cells, depending on the context.

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Oxidative stress-injured cells deliver danger signals to neighboring and distant cells, hence dictating the outcome of therapy in cancer.

Relationship between expression of NADPH oxidase 2 and invasion and prognosis of human gastric cancer

AIM: To assess the expression and prognostic value of nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) in gastric cancer, and its correlation with vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR).

METHODS: Tumor and adjacent tissues were obtained from 123 patients who underwent radical surgery for gastric cancer at Renmin Hospital of Wuhan University from 2008-2009. The expression of NOX2, VEGF, EGFR and CD68 in tumor tissues was detected by immunohistochemistry. The expression of NOX2 in gastric cancer and adjacent tissues was detected by Western blot analysis. Spearman^’s correlation was performed to elucidate the relationship of NOX2 with VEGF and EGFR. The Kaplan-Meier method was used to calculate survival time, and the log-rank test was used to evaluate differences in survival. Cox‘s proportional hazards regression model was applied in a stepwise manner to analyze the independent prognostic factors.

RESULTS: NOX2 exhibited positive expression in 47.2% (58/123) of the gastric cancer tissues. Western blot analysis revealed that NOX2 was up-regulated in tumor tissues compared to the adjacent tissue [39.0% (48/123)]. Immunohistochemistry staining revealed that CD68, which is a specific marker of macrophages, and NOX expression presented a similar localization and staining intensity. The expression of NOX2 was positively correlated with that of VEGF and EGFR. Comparison of the 5-year survival rates of the NOX2 positive and NOX2 negative groups showed that the NOX2 positive group presented a poor prognosis.

CONCLUSION: NOX2 positively correlates with the levels of VEGF and EGFR. NOX2 may be used as a new biomarker and a potential therapeutic target for gastric cancer.

Depolarization Controls TRAIL-Sensitization and Tumor-Selective Killing of Cancer Cells: Crosstalk with ROS

Conventional genotoxic anti-cancer drugs target the proliferative advantage of tumor cells over normal cells. This kind of approach lacks the selectivity of treatment to cancer cells, because most of the targeted pathways are essential for the survival of normal cells. As a result, traditional cancer treatments are often limited by undesirable damage to normal cells (side-effects). Ideal anti-cancer drugs are expected to be highly effective against malignant tumor cells with minimal cytotoxicity toward normal cells. Such selective killing can be achieved by targeting pathways essential for the survival of cancer cells, but not normal cells. As cancer cells are characterized by their resistance to apoptosis, selective apoptosis induction is a promising approach for selective killing of cancer cells. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising tumor-selective anti-cancer drug. However, the congenital and acquired resistance of some cancer cell types, including malignant melanoma cells, currently impedes effective TRAIL therapy, and an innovative approach that can override TRAIL resistance is urgently required. Apoptosis is characterized by cell shrinkage caused by disruption of the maintenance of the normal physiological concentrations of K(+) and Na(+) and intracellular ion homeostasis. The disrupted ion homeostasis leads to depolarization and apoptosis. Recent evidence suggests that depolarization is an early and prerequisite event during TRAIL-induced apoptosis. Moreover, diverse natural products and synthetic chemicals capable of depolarizing the cell membrane exhibit tumor-selective killing and TRAIL-sensitizing effects. Here, we discuss the role of depolarization in selective killing of cancer cells in connection with the emerging concept that oxidative stress is a critical mediator of mitochondrial and endoplasmic reticulum dysfunctions and serves as a tumor-selective target in cancer treatment.