Nonylphenol and octylphenol differently affect cell redox balance by modulating the nitric oxide signaling

Nonylphenol (NP) and octylphenol (OP) are pervasive environmental contaminants belonging to the broader class of compounds known as alkylphenols, with potential human toxic effects. Classified as "xenoestrogens," NP and OP are able to interfere with the cell endocrine physiology via a direct interaction with the estrogen receptors. Here, using HepG2 cells in culture, the changes of the cell redox balance and mitochondrial activity induced by OP and NP have been investigated at mu M concentrations, largely below those provoking acute toxicity, as those typical of environmental contaminants. Following 24 h cell exposure to both OP and NP, ROS production appeared significantly increased (p <= 0.01), together with the production of higher NO oxides (p = 0.003) and peroxynitrated protein-derivatives (NP versus CTR, p = 0.003). The mitochondrial proton electrochemical potential gradient instead was decreased (p <= 0.05), as the oxygen consumption by complex IV, particularly following incubation with NP (NP versus CTR, p = 0.017). Consistently, the RT-PCR and Western blot analyses proved that the OP and NP can modulate to a different extent the expression of the inducible NOS (NP versus CTR, p <= 0.01) and the endothelial NOS (OP versus CTR, p <= 0.05), with a significant variation of the coupling efficiency of the latter (NP versus CTR, p <= 0.05), a finding that may provide a novel clue to understand the specific xenoestrogenic properties of OP and NP

Administration of the antioxidant n-acetyl-cysteine in pregnant mice has long-term positive effects on metabolic and behavioral endpoints of male and female offspring prenatally exposed to a high-fat diet

A growing body of evidence suggests the consumption of high-fat diet (HFD) during pregnancy to model maternal obesity and the associated increase in oxidative stress (OS), might act as powerful prenatal stressors, leading to adult stress-related metabolic or behavioral disorders. We hypothesized that administration of antioxidants throughout gestation might counteract the negative effects of prenatal exposure to metabolic challenges (maternal HFD feeding during pregnancy) on the developing fetus. In this study, female C57BL/6J mice were fed HFD for 13 weeks (from 5-weeks of age until delivery) and were exposed to the N-acetyl-cysteine (NAC) antioxidant from 10-weeks of age until right before delivery. Body weight of the offspring was assessed following birth, up to weaning and at adulthood. The metabolic, neuroendocrine and emotional profile of the adult offspring was tested at 3-months of age. Prenatal HFD increased mother’s body weight and offspring’s weight at the time of weaning, when administered in conjunction with NAC. In females, NAC administration reduced high levels of leptin resulting from prenatal HFD. Prenatal NAC administration also resulted in greater glucose tolerance and insulin sensitivity while increasing adiponectin levels, as well as increasing exploratory behavior, an effect accompanied by reduced plasma corticosterone levels in response to restraint stress. Analysis of glutathione levels in the hypothalamus and in brown adipose tissue indicates that, while HFD administration to pregnant dams led to reduced levels of glutathione in the offspring, as in the male hypothalamus, NAC was able to revert this effect and to increase glutathione levels both in the periphery (Brown Adipose Tissue, both males and females) and in the central nervous system (males). Overall, results from this study indicate that the body redox milieu should be tightly regulated during fetal life and that buffering OS during pregnancy can have important long-term consequences on metabolic and behavioral endpoints

Antioxidant intervention against male infertility: time to design novel strategies

Infertility is a highly prevalent condition, affecting 9–20% of couples worldwide. Among the identifiable causes, the male factor stands out in about half of infertile couples, representing a growing problem. Accordingly, there has been a decline in both global fertility rates and sperm counts in recent years. Remarkably, nearly 80% of cases of male infertility (MI) have no clinically identifiable aetiology. Among the mechanisms likely plausible to account for idiopathic cases, oxidative stress (OS) has currently been increasingly recognized as a key factor in MI, through phenomena such as mitochondrial dysfunction, lipid peroxidation, DNA damage and fragmentation and finally, sperm apoptosis. In addition, elevated reactive oxygen species (ROS) levels in semen are associated with worse reproductive outcomes. However, despite an increasing understanding on the role of OS in the pathophysiology of MI, therapeutic interventions based on antioxidants have not yet provided a consistent benefit for MI, and there is currently no clear consensus on the optimal antioxidant constituents or regimen. Therefore, there is currently no applicable antioxidant treatment against this problem. This review presents an approach aimed at designing an antioxidant strategy based on the particular biological properties of sperm and their relationships with OS

NRF2: A crucial regulator for mitochondrial metabolic shift and prostate cancer progression

Metabolic alterations are a common survival mechanism for prostate cancer progression and therapy resistance. Oxidative stress in the cellular and tumor microenvironment dictates metabolic switching in the cancer cells to adopt, prosper and escape therapeutic stress. Therefore, regulation of oxidative stress in tumor cells and in the tumor-microenvironment may enhance the action of conventional anticancer therapies. NRF2 is the master regulator for oxidative stress management. However, the overall oxidative stress varies with PCa clinical stage, metabolic state and therapy used for the cancer. In agreement, the blanket use of NRF2 inducers or inhibitors along with anticancer therapies cause adverse effects in some preclinical cancer models. In this review, we have summarized the levels of oxidative stress, metabolic preferences and NRF2 activity in the different stages of prostate cancer. We also propose condition specific ways to use NRF2 inducers or inhibitors along with conventional prostate cancer therapies. The significance of this review is not only to provide a detailed understanding of the mechanism of action of NRF2 to regulate oxidative stress-mediated metabolic switching by prostate cancer cells to escape the radiation, chemo, or hormonal therapies, and to grow aggressively, but also to provide a potential therapeutic method to control aggressive prostate cancer growth by stage specific proper use of NRF2 regulators

Cardiovascular mitochondrial dysfunction induced by cocaine: biomarkers and possible beneficial effects of modulators of oxidative stress

Cocaine abuse has long been known to cause morbidity and mortality due to its cardiovascular toxic effects. The pathogenesis of the cardiovascular toxicity of cocaine use has been largely reviewed, and the most recent data indicate a fundamental role of oxidative stress in cocaine-induced cardiovascular toxicity, indicating that mitochondrial dysfunction is involved in the mechanisms of oxidative stress. The comprehension of the mechanisms involving mitochondrial dysfunction could help in selecting the most appropriate mitochondria injury biological marker, such as superoxide dismutase-2 activity and glutathionylated hemoglobin. The potential use of modulators of oxidative stress (mitoubiquinone, the short-chain quinone idebenone, and allopurinol) in the treatment of cocaine cardiotoxic effects is also suggested to promote further investigations on these potential mitochondria-targeted antioxidant strategies

Nrf2 modulation in breast cancer

Reactive oxygen species (ROS) are identified to control the expression and activity of various essential signaling intermediates involved in cellular proliferation, apoptosis, and differentiation. Indeed, ROS represents a double-edged sword in supporting cell survival and death. Many common pathological processes, including various cancer types and neurodegenerative diseases, are inflammation and oxidative stress triggers, or even initiate them. Keap1-Nrf2 is a master antioxidant pathway in cytoprotective mechanisms through Nrf2 target gene expression. Activation of the Nfr2 pathway benefits cells in the early stages and reduces the level of ROS. In contrast, hyperactivation of Keap1-Nrf2 creates a context that supports the survival of both healthy and cancerous cells, defending them against oxidative stress, chemotherapeutic drugs, and radiotherapy. Considering the dual role of Nrf2 in suppressing or expanding cancer cells, determining its inhibitory/stimulatory position and targeting can represent an impressive role in cancer treatment. This review focused on Nrf2 modulators and their roles in sensitizing breast cancer cells to chemo/radiotherapy agents

Evidence for detrimental cross interactions between reactive oxygen and nitrogen species in Leber's hereditary optic neuropathy cells

Here we have collected evidence suggesting that chronic changes in the NO homeostasis and the rise of reactive oxygen species bioavailability can contribute to cell dysfunction in Leber’s hereditary optic neuropathy (LHON) patients.We report that peripheral blood mononuclear cells (PBMCs), derived froma female LHON patient with bilateral reduced vision and carrying the pathogenic mutation 11778/ND4, display increased levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS), as revealed by flow cytometry, fluorometric measurements of nitrite/nitrate, and 3-nitrotyrosine immunodetection. Moreover, viability assays with the tetrazolium dye MTT showed that lymphoblasts from the same patient are more sensitive to prolonged NO exposure, leading to cell death. Taken together these findings suggest that oxidative and nitrosative stress cooperatively play an important role in driving LHON pathology when excess NO remains available over time in the cell environment

Nitro-oxidative stress and mitochondrial dysfunction in human cell lines exposed to the environmental contaminants PFOA and BPA

Background: Bisphenol A (BPA) and perfluorooctanoic acid (PFOA) are synthetic compounds widely utilized in industrial activities devoted to the production of daily life plastic, metal products, and packaging from which they are able to migrate to food and water. Due to their persistence in the environment, living organisms are chronically exposed to these pollutants. BPA and PFOA have adverse effects on tissues and organs. The aim of this study was to identify the molecular targets and biochemical mechanisms involved in their toxicity. Methods: HepG2 and HaCaT cells were treated with BPA or PFOA, and the trypan blue exclusion test and 3-(4,5-Dimethylthiazol-2-yl)- 2,5-Diphenyltetrazolium Bromide (MTT) assay were performed to define the conditions for subsequent investigations. We conducted quantitative PCR and western blot analysis to evaluate the expression of proteins involved in nitric oxide (NO) signaling. Cell-based assays were carried out to evaluate reactive oxygen species (ROS) production, nitrite/nitrate (NOx) accumulation, 3-nitrotyrosine (3-NT) formation, and mitochondrial membrane potential (MMP) determination in treated cells. Results: HepG2 and HaCaT cells incubated for 24 h with subtoxic concentrations of BPA or PFOA (50 and 10 μM, respectively) exhibited altered mRNA and protein expression levels of NO synthase isoforms, manganese superoxide dismutase, and cytochrome c. Treatment with PFOA led to activation of inducible NO synthase (NOS), a marker of nitrosative stress, accompanied by the increased production of ROS, NOx, and 3-NT and alterations of the MMP compared to controls. Conclusions: The results of this study indicate the major involvement of the NO signaling axis in the persistent alteration of cell redox homeostasis and mitochondrial dysfunction induced by BPA and PFOA, highlighting the specific role of PFOA in NOS regulation and induction of nitro-oxidative stress

Role of membrane potential on the control of cytochrome c oxidase over respiration in intact hepatoma HepG2 cells

Metabolic control analysis (MCA) has been largely applied to the analysis of oxidative phosphorylation, in order to investigate the control exerted by each individual reaction step on the whole pathway. Using this approach, the control exerted by the electron transport chain complexes was shown to be higher in experimental systems closer to in vivo conditions than in mitochondria. To study the effect of the mitochondrial transmembrane proton electrochemical gradient (ΔμH+) on the control of respiration by cytochrome c oxidase (CcOX) in intact cells, we applied MCA to mitochondrial respiration of HepG2 cells. Both the overall O2 consumption and specific CcOX activity of actively phosphorylating cells were progressively inhibited by cyanide titration under conditions in which the electrical (Δψ) and/or the chemical (ΔpH) component of ΔμH+ was selectively modulated by addition of ionophores. Under endogenous conditions, i.e., in the absence of ionophores, CcOX displayed a high control coefficient value, thus representing an important site of regulation of mitochondrial oxidative phosphorylation. A high CcOX control coefficient value was also measured in the presence of nigericin, when Δψ is maximal, and in the presence of nigericin and valinomycin, when ΔμH+ is abolished. On the contrary and interestingly CcOX displayed a markedly lower control coefficient in the presence valinomycin converting Δψ into ΔpH. These results show that CcOX activity and its control over oxidative phosphorylation critically depend on Δψ in actively phosphorylating cells