The role of mitochondria in pharmacotoxicology: a reevaluation of an old, newly emerging topic

Evaluation of in vitro effects of ifosfamide drug on mitochondrial functions using isolated mitochondria obtained from vital organs

Mitochondrial toxicity has been shown to contribute to a variety of organ toxicities such as, brain, heart, kidney, and liver. Ifosfamide (IFO) as an anticancer drug, is associated with increased risk of neurotoxicity, cardiotoxicity nephrotoxicity, hepatotoxicity, and hemorrhagic cystitis. The aim of this study was to evaluate the direct effect of IFO on isolated mitochondria obtained from the rat brain, heart, kidney, and liver. Mitochondria were isolated with mechanical lysis and differential centrifugation from different organs and treated with various concentrations of IFO. Using biochemical and flowcytometry assays, we evaluated mitochondrial succinate dehydrogenase (SDH) activity, mitochondrial swelling, lipid peroxidation, reactive oxygen species (ROS) production, and mitochondrial membrane potential (MMP). Our data showed that IFO did not cause deleterious alterations in mitochondrial functions, mitochondrial swelling, lipid peroxidation ROS formation, and MMP collapse in mitochondria isolated from brain, heart, kidney, and liver. Altogether, the data showed that IFO is not directly toxic in mitochondria isolated from brain, heart, kidney, and liver. This study proved that mitochondria alone does not play the main role in the toxicity of IFO, and suggests to reduce the toxicity of this drug, other pathways resulting in the production of toxic metabolites should be considered.

Multimarker Responses of Zebrafish to the Effect of Ibuprofen and Gemfibrozil in Environmentally Relevant Concentrations

Pharmaceutical pollution of water bodies is among the top-notch environmental health risks all over the world. The aim of the present study was to investigate the effects of two common pharmaceuticals namely ibuprofen and gemfibrozil on zebrafish at environmentally relevant concentrations. In zebrafish liver, gemfibrozil caused a decrease in glutathione and glutathione transferase and an increase in catalase but had no effect on lipid peroxidation and protein carbonylation. Ibuprofen altered the antioxidant defense system, promoted protein carbonylation in zebrafish liver, and increased vitellogenin-like protein in the blood. Ibuprofen and particularly gemfibrozil induced lysosomes biogenesis. Lactate dehydrogenase in the blood was also found to be higher in the studied groups. Studied pharmaceuticals did not affect complex II of the electron respiratory chain. Ibuprofen affects zebrafish health status more profoundly than gemfibrozil. Our results showed that pharmaceuticals even in low, environmentally realistic concentrations, induced profound changes in the stress-responsive systems of zebrafish.

Agomelatine, Ketamine and Vortioxetine Attenuate Energy Cell Metabolism-In Vitro Study

This determination of the mitochondrial effect of pharmacologically different antidepressants (agomelatine, ketamine and vortioxetine) was evaluated and quantified in vitro in pig brain-isolated mitochondria. We measured the activity of mitochondrial complexes, citrate synthase, malate dehydrogenase and monoamine oxidase, and the mitochondrial respiratory rate. Total hydrogen peroxide production and ATP production were assayed. The most potent inhibitor of all mitochondrial complexes and complex I-linked respiration was vortioxetine. Agomelatine and ketamine inhibited only complex IV activity. None of the drugs affected complex II-linked respiration, citrate synthase or malate dehydrogenase activity. Hydrogen peroxide production was mildly increased by agomelatine, which might contribute to increased oxidative damage and adverse effects at high drug concentrations. Vortioxetine significantly reduced hydrogen peroxide concentrations, which might suggest antioxidant mechanism activation. All tested antidepressants were partial MAO-A inhibitors, which might contribute to their antidepressant effect. We observed vortioxetine-induced MAO-B inhibition, which might be linked to decreased hydrogen peroxide formation and contribute to its procognitive and neuroprotective effects. Mitochondrial dysfunction could be linked to the adverse effects of vortioxetine, as vortioxetine is the most potent inhibitor of mitochondrial complexes and complex I-linked respiration. Clarifying the molecular interaction between drugs and mitochondria is important to fully understand their mechanism of action and the connection between their mechanisms and their therapeutic and/or adverse effects.

Mitochondrial Respiratory Complexes as Targets of Drugs: The PPAR Agonist Example

Mitochondrial bioenergetics are progressively acquiring significant pathophysiological roles. Specifically, mitochondria in general and Electron Respiratory Chain in particular are gaining importance as unintentional targets of different drugs. The so-called PPAR ligands are a class of drugs which not only link and activate Peroxisome Proliferator-Activated Receptors but also show a myriad of extrareceptorial activities as well. In particular, they were shown to inhibit NADH coenzyme Q reductase. However, the molecular picture of this intriguing bioenergetic derangement has not yet been well defined. Using high resolution respirometry, both in permeabilized and intact HepG2 cells, and a proteomic approach, the mitochondrial bioenergetic damage induced by various PPAR ligands was evaluated. Results show a derangement of mitochondrial oxidative metabolism more complex than one related to a simple perturbation of complex I. In fact, a partial inhibition of mitochondrial NADH oxidation seems to be associated not only with hampered ATP synthesis but also with a significant reduction in respiratory control ratio, spare respiratory capacity, coupling efficiency and, last but not least, serious oxidative stress and structural damage to mitochondria.

Genomic organization, evolution and functional characterization of caspase-2 and caspase-8 in miiuy croaker (Miichthys miiuy)

As the central link and executor of cell apoptosis, the caspase protease family has received extensive attention in recent years. However, the genetic characteristics and immune functions of some caspases are still unknown in fish. In our study, we cloned the full-length caspase-2 (mmCasp2) and caspase-8 (mmCasp2) of miiuy croaker, then we analyzed characteristics and functions of these two genes which are upstream of the apoptosis cascade reaction. Mmcasp2 and mmCasp8 exhibited a conserved domain (CASc), and the different part is that the mmCasp2 has a CARD domain, while mmCasp8 have two DED domains. Sequence and evolution analysis results showed that caspase-2 is more conservative than caspae-8 in the process of evolution. Cellular localization analysis showed that the distribution of mmCasp2 and mmCasp2 was in cytoplasm. The real-time PCR analysis showed that these two caspases are constitutively expressed in different tissues, and the expression of mmCasp2 and mmCasp8 were up-regulated in the liver, spleen, and kidney after infection with V. anguillarum. Lastly, qRT-PCR and Luciferase assays analysis showed that mmCasp2 and mmCasp8 can inhibit the NF-кB pathway. In general, we systematically analyzed the structure, evolution and related functional experiments of the caspase-2 and caspase-8 in miiuy croaker, which will help further understand the role caspase family plays in the apoptosis and immune response.

Research progress of non-steroidal anti-inflammatory drug-induced small intestinal injury

Non-steroidal anti-inflammatory drugs (NSAIDs) are used widely around the world because of their anti-inflammatory, analgesic, and antiplatelet activity. However, long-term application of NSAIDs can lead to complications. Previously, the clinical attention was dedicated to the NSAID-induced upper gastrointestinal complications. Recently, the detection rate of small intestinal damage related to NSAIDs has increased due to the wide use of endoscopes such as capsule endoscopy and double-balloon colonoscopy. Although the majority of patients have no significant symptoms, there are still a small percentage of patients who develop obvious symptoms or complicated ulcers that require therapeutic intervention. Despite significant advances in our understanding of NSAIDs, the treatment modality and regimen for NSAID-induced small intestinal damage have remained relatively unclear. This article will provide a comprehensive overview of NSAID-induced small intestinal damage with regard to the epidemiology, clinical manifestations, diagnosis, risk factors, pathogenesis, and treatment, in order to provide informative evidence for clinical practice.

Quality Matters? The Involvement of Mitochondrial Quality Control in Cardiovascular Disease

Cardiovascular diseases are one of the leading causes of death and global health problems worldwide. Multiple factors are known to affect the cardiovascular system from lifestyles, genes, underlying comorbidities, and age. Requiring high workload, metabolism of the heart is largely dependent on continuous power supply via mitochondria through effective oxidative respiration. Mitochondria not only serve as cellular power plants, but are also involved in many critical cellular processes, including the generation of intracellular reactive oxygen species (ROS) and regulating cellular survival. To cope with environmental stress, mitochondrial function has been suggested to be essential during bioenergetics adaptation resulting in cardiac pathological remodeling. Thus, mitochondrial dysfunction has been advocated in various aspects of cardiovascular pathology including the response to ischemia/reperfusion (I/R) injury, hypertension (HTN), and cardiovascular complications related to type 2 diabetes mellitus (DM). Therefore, mitochondrial homeostasis through mitochondrial dynamics and quality control is pivotal in the maintenance of cardiac health. Impairment of the segregation of damaged components and degradation of unhealthy mitochondria through autophagic mechanisms may play a crucial role in the pathogenesis of various cardiac disorders. This article provides in-depth understanding of the current literature regarding mitochondrial remodeling and dynamics in cardiovascular diseases.

Direct Antiviral Treatments for Hepatitis C Virus Have Off-Target Effects of Oncologic Relevance in Hepatocellular Carcinoma

Simple Summary

Hepatitis C virus (HCV) eradication by direct-acting antiviral agents (DAAs) reduces de novo hepatocellular carcinoma incidence in cirrhosis; however, contrasting evidence on higher incidence of hepatocellular carcinoma (HCC) was reported in patients previously treated for HCC. Here, we showed that sofosbuvir and daclatasvir can modulate cell proliferation, invasion capability and gene expression in HCC-derived cell lines, suggesting that off-target effects of these drugs might be responsible for both the increase and reduction of cell proliferation and migration capability. Off-target gene modulation, mainly affecting mitochondrial functions, ribosomal genes and histones, was consistent with matched phenotypic changes and might account either for pro-oncogenic or tumor-suppressive functions of DAAs, that seemed to be dictated by the molecular background.

Abstract

Background and Aims: HCV eradication by direct-acting antiviral agents (DAAs) reduces de novo hepatocellular carcinoma (HCC) incidence in cirrhosis; however, contrasting evidence about beneficial or detrimental effects still exists in patients who have already developed HCC. Methods: we investigated whether sofosbuvir and daclatasvir modulate cell proliferation, invasion capability and gene expression (RNA-seq) in HCC-derived cell lines, hypothesizing possible off-target effects of these drugs. Results observed in HCC cell lines were validated in non-HCC cancer-derived cell lines and a preliminary series of human HCC tissues by qPCR and IHC. Results: DAAs can affect HCC cell proliferation and migration capability by either increasing or reducing them, showing transcriptomic changes consistent with some unexpected drug-associated effects. Off-target gene modulation, mainly affecting ribosomal genes, mitochondrial functions and histones, points to epigenetics and proliferation as relevant events, consistent with matched phenotypic changes. A preliminary validation of in vitro findings was performed in a restricted cohort of HCC patients previously treated with DAAs, with immunohistochemical correlations suggesting DAA-treated HCCs to be more aggressive in terms of migration and epidermal-to-mesenchymal transition. Conclusions: Our findings suggested the possible occurrence of off-target effects ultimately modulating cell proliferation and/or migration and potentially justified previous findings showing some instances of particularly aggressive HCC recurrence as well as reduced incidence of recurrence of HCC following treatment with DAAs.

Current knowledge on non-steroidal anti-inflammatory drug-induced small-bowel damage: a comprehensive review

Recent advances in small-bowel endoscopy such as capsule endoscopy have shown that non-steroidal anti-inflammatory drugs (NSAIDs) frequently damage the small intestine, with the prevalence rate of mucosal breaks of around 50% in chronic users. A significant proportion of patients with NSAIDs-induced enteropathy are asymptomatic, but some patients develop symptomatic or complicated ulcers that need therapeutic intervention. Both inhibition of prostaglandins due to the inhibition of cyclooxygenases and mitochondrial dysfunction secondary to the topical effect of NSAIDs play a crucial role in the early process of injury. As a result, the intestinal barrier function is impaired, which allows enterobacteria to invade the mucosa. Gram-negative bacteria and endogenous molecules coordinate to trigger inflammatory cascades via Toll-like receptor 4 to induce excessive expression of cytokines such as tumor necrosis factor-α and to activate NLRP3 inflammasome, a multiprotein complex that processes pro-interleukin-1β into its mature form. Finally, neutrophils accumulate in the mucosa, resulting in intestinal ulceration. Currently, misoprostol is the only drug that has a proven beneficial effect on bleeding small intestinal ulcers induced by NSAIDs or low-dose aspirin, but its protection is insufficient. Therefore, the efficacy of the combination of misoprostol with other drugs, especially those targeting the innate immune system, should be assessed in the next step.

Network Pharmacology Approach Reveals the Potential Immune Function Activation and Tumor Cell Apoptosis Promotion of Xia Qi Decoction in Lung Cancer

As the leading cause of cancer death worldwide, lung cancer (LC) has seriously affected human health and longevity. Chinese medicine is a complex system guided by traditional Chinese medicine theories (TCM). Nowadays, the clinical application of TCM for LC patients has become the focus for its effectiveness and security. In this paper, we will analyze and study the mechanism of Xia Qi Decoction (XQD) in the treatment of LC. The results collectively show that XQD could act on 41 therapeutic targets of LC. At the same time, 8 of 41 targets were significantly expressed in immune tissues and cells by activating CD8+T cells to promote apoptosis of cancer cells. It reveals the molecular mechanism of XQD in the treatment of LC from the perspective of network pharmacology. In addition, in the treatment of LC, XQD can activate (up-regulate) the function of immune cells, promote the apoptosis of tumor cells, and have an active anti-tumor immune effect. In conclusion, this study reveals the unique advantages of traditional Chinese medicine in the treatment of cancer, in reinforcing the healthy qi and eliminating the pathogenic factors. More research, however, is needed to verify the potential mechanisms.

Research progress on the relationship between lung cancer drug-resistance and microRNAs

Lung cancer, a malignant tumor with the highest death rate of cancer, seriously endangers human health. And its pathogenesis and mechanism of drug resistance has been partially clarified, especially for the signal pathway of epidermal growth factor receptor (EGFR). The targeting therapy of EGFR signaling pathway in non-small cell lung cancer (NSCLC) has achieved a certain effect, but the two mutation of EGFR and other mechanisms of lung cancer resistance still greatly reduce the therapeutic effect of chemotherapy on it. MicroRNA is an endogenous non coding RNA, which has a regulatory function after transcriptional level. Recent studies on the mechanism of lung cancer resistance have found that a variety of microRNAs are related to the mechanism of lung cancer drug-resistance. They can regulate lung cancer resistance by participating in signal pathways, drug resistance genes and cell apoptosis, thus affecting the sensitivity of cancer cells to drugs. Therefore, microRNAs can be used as a specific target for the treatment of lung cancer and plays a vital role in the early diagnosis, prognosis and treatment of lung cancer. This article reviews the mechanisms of lung cancer resistance and its relationship with microRNAs.

Progressive study of effects of erianin on anticancer activity

Erianin is the major bisbenzyl compound extracted from the traditional Chinese medicine Dendrohium chrysotoxum Lindl. Erianin possesses many biological properties relevant to cancer prevention and therapy. The previous studies confirmed that antitumor effects of erianin are regulated with multiple signaling pathways. The mechanisms of erianin are numerous, and most of them induce cancer cell apoptosis that may be intrinsic or extrinsic and modulate the ROS/JNK signaling pathways. Invasion, migration, and angiogenesis represent emerging targets of erianin and support its anticancer properties. This review aimed to summarize the recent advances in the antitumor activity of erianin and to provide a rationale for further exploring the potential application of erianin in overcoming cancer in the future.

Control of invasive sea lampreys using the piscicides TFM and niclosamide: Toxicology, successes & future prospects

The invasion of the Laurentian Great Lakes of North America by sea lampreys (Petromyzon marinus) in the early 20th century contributed to the depletion of commercial, recreational and culturally important fish populations, devastating the economies of communities that relied on the fishery. Sea lamprey populations were subsequently controlled using an aggressive integrated pest-management program which employed barriers and traps to prevent sea lamprey from migrating to their spawning grounds and the use of the piscicides (lampricides) 3-trifluoromethyl-4-nitrophenol (TFM) and niclosamide to eliminate larval sea lampreys from their nursery streams. Although sea lampreys have not been eradicated from the Great Lakes, populations have been suppressed to less than 10% of their peak numbers in the mid-1900s. The ongoing use of lampricides provides the foundation for sea lamprey control in the Great Lakes, one of the most successful invasive species control programs in the world. Yet, significant gaps remain in our understanding of how lampricides are taken-up and handled by sea lampreys, how lampricides exert their toxic effects, and how they adversely affect non-target invertebrate and vertebrates species. In this review we examine what has been learned about the uptake, handling and elimination, and the mode of TFM and niclosamide toxicity in lampreys and in non-target animals, particularly in the last 10 years. It is now clear that the mode of TFM toxicity is the same in non-target fishes and lampreys, in which TFM interferes with oxidative phosphorylation by the mitochondria leading to decreased ATP production. Vulnerability to TFM is related to abiotic factors such as water pH and alkalinity, which we propose changes the relative amounts of the bioavailable un-ionized form of TFM in the gill microenvironment. Niclosamide, which is also a molluscicide used to control snails in areas prone to schistosomiasis infections of humans, also likely works by uncoupling oxidative phosphorylation, but less is known about other aspects of its toxicology. The effects of TFM include reductions in energy stores, particularly glycogen and high energy phosphagens. However, non-target fishes readily recover from sub-lethal TFM exposure as demonstrated by the rapid restoration of energy stores and clearance of TFM. Although both TFM and niclosamide are non-persistent in the environment and critical for sea lamprey control, increasing public and institutional concerns about pesticides in the environment makes it imperative to explore other means of sea lamprey control. Accordingly, we also address possible "next-generation" strategies of sea lamprey control including genetic tools such as RNA interference and CRISPR-Cas9 to impair critical physiological processes (e.g. reproduction, digestion, metamorphosis) in lamprey, and the use of green chemistry to develop more environmentally benign chemical methods of sea lamprey control.

In vitro effects of antipsychotics on mitochondrial respiration

Assessment of drug-induced mitochondrial dysfunctions is important in drug development as well as in the understanding of molecular mechanism of therapeutic or adverse effects of drugs. The aim of this study was to investigate the effects of three typical antipsychotics (APs) and seven atypical APs on mitochondrial bioenergetics. The effects of selected APs on citrate synthase, electron transport chain complexes (ETC), and mitochondrial complex I- or complex II-linked respiratory rate were measured using mitochondria isolated from pig brain. Complex I activity was decreased by chlorpromazine, haloperidol, zotepine, aripiprazole, quetiapine, risperidone, and clozapine. Complex II + III was significantly inhibited by zotepine, aripiprazole, quetiapine, and risperidone. Complex IV was inhibited by zotepine, chlorpromazine, and levomepromazine. Mitochondrial respiratory rate was significantly inhibited by all tested APs, except for olanzapine. Typical APs did not exhibit greater efficacy in altering mitochondrial function compared to atypical APs except for complex I inhibition by chlorpromazine and haloperidol. A comparison of the effects of APs on individual respiratory complexes and on the overall mitochondrial respiration has shown that mitochondrial functions may not fully reflect the disruption of complexes of ETC, which indicates AP-induced modulation of other mitochondrial proteins. Due to the complicated processes associated with mitochondrial activity, it is necessary to measure not only the effect of the drug on individual mitochondrial enzymes but also the respiration rate of the mitochondria or a similar complex process. The experimental approach used in the study can be applied to mitochondrial toxicity testing of newly developed drugs.

Effect of Chronic Exposure to Methomyl on Tissue Damage and Apoptosis in Testis of Tilapia (Oreochromis niloticus) and Recovery Pattern

Tilapia were exposed to 0, 0.2, 2, 20, 200 µg/L methomyl for 30 days, and then transferred to methomyl-free water for 18 days. Caspase-8 in serum, apoptosis rate, microstructure and ultra-microstructure of testis were checked after methomyl exposure and at 18 days after transferring to methomyl-free water. There were no significant changes in Caspase-8 activity, apoptosis rate, and tissue structure in testis exposed to 0.2 and 2 µg/L compared with control. However, when tilapia exposed to 20 and 200 µg/L, the Caspase-8 activity and apoptosis rate were induced significantly, and tissue damage happened compared with the control. Thus it would appear 2 µg/L methomyl might be considered as the no observed adverse effect level. Recovery data showed that the effects produced by lower concentration of 20 µg/L were reversible but not at the higher 200 µg/L concentration.

Theaflavins attenuate ethanol‑induced oxidative stress and cell apoptosis in gastric mucosa epithelial cells via downregulation of the mitogen‑activated protein kinase pathway

Ethanol‑induced diseases of the gastric mucosa are the most common and refractory diseases of gastrointestinal system in clinic, and are mediated by oxidative stress and apoptosis pathways. Theaflavins (TFs) are considered to be antioxidants. The present study aimed to determine the molecular mechanism underlying the ability of TFs to attenuate ethanol‑induced oxidative stress and apoptosis in GES‑1 gastric mucosa epithelial cells. A Cell Counting Kit‑8 (CCK‑8) assay was performed to investigate the cell viability of GES‑1 cells following administration of ethanol (0.5 mol/l) and subsequent treatment with TFs (20, 40 and 80 µg/ml) for specific time intervals. A carboxyfluorescein diacetate succinimidyl ester assay was used to measure proliferation and further investigate the results of the CCK‑8 assay. Flow cytometry was performed to measure reactive oxygen species (ROS) levels and the apoptosis rates of GES‑1 cells. Furthermore, levels of oxidative stress‑associated factors, including malondialdehyde, superoxide dismutase and glutathione, were investigated using commercial kits. Reverse transcription‑quantitative polymerase chain reaction and western blot assays were performed to determine the expression levels of apoptosis‑associated factors, as well as the phosphorylation levels of extracellular signal‑regulated kinase (ERK), c‑Jun N‑terminal kinase (JNK) and p38 kinase (p38). The results of the present study demonstrated that treatment with ethanol inhibited GES‑1 cell proliferation, and enhanced ROS levels and apoptosis rates, potentially via downregulation of B‑cell lymphoma‑2 (Bcl‑2) expression and upregulation of Bcl‑2‑associated X and caspase‑3 expression levels, as well as enhancing the phosphorylation levels of ERK, JNK and p38. However, treatment with TFs was revealed to attenuate the effects of ethanol administration on GES‑1 cells in a dose‑dependent manner. In conclusion, TFs may attenuate ethanol‑induced oxidative stress and apoptosis in gastric mucosa epithelial cells via downregulation of various mitogen‑activated protein kinase pathways.

Mechanistic effect of the human GJB6 gene and its mutations in HaCaT cell proliferation and apoptosis

We constructed lentiviral vectors containing the human wild-type GJB6 gene and the mutant variants A88V and G11R. The three proteins were stably expressed by the Tet-on system in the HaCaT cell line and used to study the functional effect of the variants. The CCK-8 assay and flow cytometric analyses were used to determine the levels of cell proliferation and apoptosis. Western blot analyses were performed to analyze the relevant clinical indicators of hidrotic ectodermal dysplasia and markers of apoptosis in transfected HaCaT cells. The CCK8 assay and the flow cytometry results showed a significant increase (P<0.05) in the apoptosis of HaCaT cells expressing the A88V and G11R mutants. In addition, we demonstrated that the A88V and G11R mutants induced the apoptosis of transfected HaCaT cells via the activation of caspase-3, -8, -9, and PARA. No change was observed in the activity of BAX compared with the control. This study provides further clarification on the mechanisms underlying the effect of the mutant variants A88V and G11R of the GJB6 gene on the induction of HaCaT cell apoptosis.

High expression of active ATF6 aggravates endoplasmic reticulum stress‑induced vascular endothelial cell apoptosis through the mitochondrial apoptotic pathway

Activating transcription factor 6 (ATF6), one of three sensor proteins in the endoplasmic reticulum (ER), is an important regulatory factor in the ER stress‑induced apoptosis pathway. Although recent studies have made some progress in elucidating the regulation mechanism of ATF6, the specific regulatory mechanism of ER stress‑induced vascular endothelial cell (VEC) apoptosis is still unclear. The present study was designed to investigate the role of ATF6 in VECs under thapsigargin (TG)‑induced ER stress. ATF6 (1‑366aa; ATF6 high‑expressed plasmid) and ATF6 (151‑366aa; plasmid without transcriptional activity) were transfected into VECs to yield an ATF6 high‑expression model and a positive control model, respectively. High expression of ATF6 decreased viability and aggravated ER stress‑induced apoptosis in VECs. Increased expression of apoptosis‑related genes, including those encoding caspase‑3, caspase‑9, C/EBP homologous protein (CHOP), cytochrome c and B‑cell lymphoma‑associated protein X (Bax)/B‑cell lymphoma (Bcl‑)2, was detected by polymerase chain reaction and western blotting in the ATF6 (1‑366aa) + TG group. No significant effect of TG treatment and high ATF6 expression was indicated on the expression of death receptor‑related genes, including those encoding caspase‑8 and Fas. The results demonstrated that high expression of activated ATF6 aggravates ER stress‑induced VEC apoptosis through the mitochondrial apoptotic pathway. Furthermore, in response to ER stress, ATF6 upregulates the expression of caspase‑3, caspase‑9, CHOP, cytochrome c and Bax/Bcl‑2.

Decrypting Strong and Weak Single-Walled Carbon Nanotubes Interactions with Mitochondrial Voltage-Dependent Anion Channels Using Molecular Docking and Perturbation Theory

The current molecular docking study provided the Free Energy of Binding (FEB) for the interaction (nanotoxicity) between VDAC mitochondrial channels of three species (VDAC1-Mus musculus, VDAC1-Homo sapiens, VDAC2-Danio rerio) with SWCNT-H, SWCNT-OH, SWCNT-COOH carbon nanotubes. The general results showed that the FEB values were statistically more negative (p < 0.05) in the following order: (SWCNT-VDAC2-Danio rerio) > (SWCNT-VDAC1-Mus musculus) > (SWCNT-VDAC1-Homo sapiens) > (ATP-VDAC). More negative FEB values for SWCNT-COOH and OH were found in VDAC2-Danio rerio when compared with VDAC1-Mus musculus and VDAC1-Homo sapiens (p < 0.05). In addition, a significant correlation (0.66 > r² > 0.97) was observed between n-Hamada index and VDAC nanotoxicity (or FEB) for the zigzag topologies of SWCNT-COOH and SWCNT-OH. Predictive Nanoparticles-Quantitative-Structure Binding-Relationship models (nano-QSBR) for strong and weak SWCNT-VDAC docking interactions were performed using Perturbation Theory, regression and classification models. Thus, 405 SWCNT-VDAC interactions were predicted using a nano-PT-QSBR classifications model with high accuracy, specificity, and sensitivity (73–98%) in training and validation series, and a maximum AUROC value of 0.978. In addition, the best regression model was obtained with Random Forest (R² of 0.833, RMSE of 0.0844), suggesting an excellent potential to predict SWCNT-VDAC channel nanotoxicity. All study data are available at https://doi.org/10.6084/m9.figshare.4802320.v2.

Mitochondria sustain store-operated currents in colon cancer cells but not in normal colonic cells: reversal by non-steroidal anti-inflammatory drugs

Tumor cells undergo a critical remodeling of intracellular Ca²⁺ homeostasis that contribute to important cancer hallmarks. Store-operated Ca²⁺ entry (SOCE), a Ca²⁺ entry pathway modulated by mitochondria, is dramatically enhanced in colon cancer cells. In addition, most cancer cells display the Warburg effect, a metabolic switch from mitochondrial metabolism to glycolysis that provides survival advantages. Accordingly, we investigated mitochondria control of store-operated currents (SOCs) in two cell lines previously selected for representing human normal colonic cells and colon cancer cells. We found that, in normal cells, mitochondria are important for SOCs activity but they are unable to prevent current inactivation. In contrast, in colon cancer cells, mitochondria are dispensable for SOCs activation but are able to prevent the slow, Ca²⁺-dependent inactivation of SOCs. This effect is associated to increased ability of tumor cell mitochondria to take up Ca²⁺ due to increased mitochondrial potential (ΔΨ) linked to the Warburg effect. Consistently with this view, selected non-steroidal anti-inflammatory drugs (NSAIDs) depolarize mitochondria, inhibit mitochondrial Ca²⁺ uptake and promote SOC inactivation, leading to inhibition of both SOCE and cancer cell proliferation. Thus, mitochondria sustain store-operated currents in colon cancer cells but not in normal colonic cells and this effect is counteracted by selected NSAIDs providing a mechanism for cancer chemoprevention.

C-Glycosyl Flavonoids from Beta vulgaris Cicla and Betalains from Beta vulgaris rubra: Antioxidant, Anticancer and Antiinflammatory Activities-A Review

The green beet (Beta vulgaris var. cicla L.) and red beetroot (B. vulgaris var. rubra L.) contain phytochemicals that have beneficial effects on human health. Specifically, the green beet contains apigenin, vitexin, vitexin-2-O-xyloside and vitexin-2-O-rhamnoside, while the red beetroot is a source of betaxanthins and betacyanins. These phytochemicals show considerable antioxidant activity, as well as antiinflammatory and antiproliferative activities. Vitexin-2-O-xyloside, in combination with betaxanthins and betacyanins, exerts antiproliferative activity in breast, liver, colon and bladder cancer cell lines, through the induction of both intrinsic and extrinsic apoptotic pathways. A significant body of evidence also points to the role of these phytochemicals in the downregulation of the pro-survival genes, baculoviral inhibitor of apoptosis repeat-containing 5 and catenin beta-1, as well as the genes controlling angiogenesis, hypoxia inducible factor 1A and vascular endothelial growth factor A. The multi-target action of these phytochemicals enhances their anticancer activity. Vitexin-2-O-xyloside, betaxanthins and betacyanins can be used in combination with conventional anticancer drugs to reduce their toxicity and overcome the multidrug resistance of cancer cells. In this review, we describe the molecular mechanisms that enable these dietary phytochemicals to block the proliferation of tumor cells and inhibit their pro-survival pathways. Copyright © 2017 John Wiley & Sons, Ltd.

Organ-specific effects of low-dose zinc pre-exposure on high-dose zinc induced mitochondrial dysfunction in large yellow croaker Pseudosciaena crocea

The study was carried out to evaluate the effects of low-dose zinc (Zn) pre-exposure on survival rate, new Zn accumulation, and mitochondrial bioenergetics in the liver and spleen of large yellow croaker exposed to high-dose Zn. To the end, fish were pre-exposed to 0 and 2 mg L^-1 Zn for 48 h and post-exposed to 0 and 12 mg L^-1 Zn for 48 h. Twelve milligrams Zn per liter exposure alone reduced survival rate, but the effect did not appear in the 2 mg L^-1 Zn pre-exposure groups. Two milligrams per liter Zn pre-exposure also ameliorated 12 mg Zn L^-1 induced new Zn accumulation, reactive oxygen species (ROS) levels, and mitochondrial swelling in the liver. However, these effects did not appear in the spleen. In the liver, 2 mg L^-1 Zn pre-exposure apparently relieved 12 mg L^-1 Zn induced down-regulation of activities of ATP synthase (F-ATPase), succinate dehydrogenase (SDH), and malate dehydrogenase (MDH). The mRNA levels of these genes remained relatively stable in fish exposed to 12 mg L^-1 Zn alone, but increased in fish exposed to 12 mg L^-1 Zn with 2 mg L^-1 Zn pre-treatment. In the spleen, 2 mg Zn L^-1 pre-exposure did not mitigate the down-regulation of mRNA levels of genes and activities of relative enzymes induced by 12 mg L^-1 Zn. In conclusion, our study demonstrated low-dose zinc pre-exposure ameliorated high-dose zinc induced mitochondrial dysfunction in the liver but not in the spleen of large yellow croaker, indicating an organ-specific effect.

DNMT1 modulation in chronic hepatitis B patients and hypothetic influence on mitochondrial DNA methylation status during long-term nucleo(t)side analogs therapy

Inhibition of viral replication is the most important goal in patients with Hepatitis B virus chronic infection (CHB). Currently, five oral nucleo(t)side analogs (NAs), including Lamivudine, Adefovir, Telbivudine, Entecavir, and Tenofovir, have been approved for treatment. The widespread use of NAs has also been linked with a progressive growth of unlikely anomaly attributable to mitochondrial dysfunctions, not previously recognized. Here, we explore the hypothesis that NAs may cause persistent epigenetic changes during prolonged NAs therapy in CHB patients. We obtained peripheral blood mononuclear cells (PBMC) from whole blood samples of consecutive patients with chronic HBV infection, 18 receiving NAs and 20 untreated patients. All patients were Caucasian and Italians. Epigenetic analysis was performed by Bisulphite sequencing PCR to search the existence of methylated cytosine residues in the Light (L)-strands of mitochondrial DNA control region (D-loop). Gene expression analysis of DNA methyltransferases 1 was performed by a quantitative relative Real-Time Polymerase Chain Reaction (PCR). DNMT1 expression was significantly (P < 000001) higher in NA treated patients (4.09, IQR 3.52-5.15) when compared with HBV naives (0.61, IQR 0.34-0.82). Besides, DNMT1 expression was significantly correlated with NA therapy duration (Spearman Rho = 0.67; P < 0.05). Furthermore, NA therapy duration was the only significant predictor of DNMT1 expression at multivariate analysis (Beta = 0.95, P < 0.0000001). Bisulphite PCR sequencing showed that methylation of cytosine residues occurred in a higher percentage in patients treated with NAs in comparison with untreated patients and healthy controls. Our data showed a DNMT1 overexpression significantly correlated to NA therapy duration and an higher regional mtDNA hypermethylation. This might suggest an epigenetic alteration that could be involved in one of the possible mechanisms of mitochondrial gene regulation during NAs therapy.

Hepatic Lipodystrophy in Galloway Calves

Hepatic lipodystrophy in Galloway calves is a fatal liver disease affecting a small proportion of the Galloway breed described in different parts of Europe and North America during the past decades. The clinical findings include a diversity of neurological signs. Clinical pathology findings frequently indicate hepatobiliary disease. Postmortem examination reveals an enlarged, pale yellow, and firm liver. Histologic lesions include hepatic fibrosis, hepatic lipidosis, and bile duct hyperplasia. To date, the etiopathogenesis remains obscure. Infectious causes, intoxications, and a hereditary origin have been considered. We describe hepatic lipodystrophy in Galloway calves from an extensively farmed cow-calf operation in southern Germany. Main clinical findings in 6 calves were consistent with hepatic encephalopathy. Clinical pathology findings in 5 of 6 tested animals revealed increased concentration of total bilirubin (maximum value [MV], 54 μmol/l; reference range [RR], <8.5 μmol/l), direct bilirubin (MV, 20 μmol/l; RR, <3.4 μmol/l), increased activity of gamma glutamyl transferase (MV, 162 U/l; RR, <36 U/l) and glutamate dehydrogenase (MV, 420 U/l; RR, <16 U/l). In addition, activity of glutathione peroxidase was decreased in all tested ( n = 5) animals (MV, 61 U/g hemoglobin [Hb]; RR, >250 U/g Hb). Postmortem examination in 6 calves revealed a firm, diffusely enlarged yellow liver with a finely nodular surface. Histologic lesions included hepatic fibrosis, hepatic lipidosis, and bile duct hyperplasia. Our findings add to the existing data on hepatic lipodystrophy in the Galloway breed and outline a protocol to aid in the diagnosis of this disorder.

Mitochondrial Disorder Aggravated by Metoprolol

Beta-adrenergic blocking agents or beta-blockers are a class of medications used to treat cardiac arrhythmias and systemic hypertension. In therapeutic dosages, they have known adverse outcomes that can include muscular fatigue and cramping, dizziness, and dyspnea. In patients with mitochondrial disease, these effects can be amplified. Previous case reports have been published in the adult population; however, their impact in pediatric patients has not been reported. We describe a pediatric patient with a mitochondrial disorder who developed respiratory distress after metoprolol was prescribed for hypertension. As the patient improved with discontinuation of medication and no alternative etiology was found for symptoms, we surmise that administration of metoprolol aggravated his mitochondrial dysfunction, thus worsening underlying chest wall weakness.

A high-throughput screen for mitochondrial function reveals known and novel mitochondrial toxicants in a library of environmental agents

Mitochondrial toxicity is emerging as a major mechanism underlying serious human health consequences. This work performs a high-throughput screen (HTS) of 176 environmental chemicals for mitochondrial toxicity utilizing a previously reported biosensor platform. This established HTS confirmed known mitochondrial toxins and identified novel mitotochondrial uncouplers such as 2, 2'-Methylenebis(4-chlorophenol) and pentachlorophenol. It also identified a mitochondrial 'structure activity relationship' (SAR) in the sense that multiple environmental chlorophenols are mitochondrial inhibitors and uncouplers. This study demonstrates proof-of-concept that a mitochondrial HTS assay detects known and novel environmental mitotoxicants, and could be used to quickly evaluate human health risks from mitotoxicants in the environment.

Possible role of mitochondrial injury in Caulis Aristolochia manshuriensis-induced chronic aristolochic acid nephropathy

CONTEXT

The proximal tubular epithelial cells (PTECs) are the primary target of aristolochic acids and especially vulnerable to mitochondrial injury from insults of toxic xenobiotics.

OBJECTIVES

This study aimed to investigate the possible role of mitochondrial injury in Caulis Aristolochia manshuriensis (CAM)-induced aristolochic acid nephropathy (AAN).

MATERIALS AND METHODS

Male Sprague-Dawley rats were gavaged with CAM extract every other week for 1, 4, 8 and 12 weeks, respectively.

RESULTS

The rats in the model group showed chronic AAN as evidenced by worsening kidney function evaluated by blood urea nitrogen, creatinine and proteinuria levels, and severe tubulointerstitial injury marked by massive tubular atrophy and interstitial fibrosis in kidney tissues. Moreover, overt apoptosis and impaired regeneration of PTECs were observed in AAN rats. Furthermore, the study revealed that mitochondria in PTECs were fragmented into small, punctuate suborganelles in AAN rats. Two mitochondrial respiratory chain proteins, mitochondrial DNA (mtDNA)-encoded cytochrome c oxidase subunit І (COX-І) and nuclear DNA-encoded nicotinamide adenine dinucleotide dehydrogenase (ubiquinone)-1β subcomplex 8 (NDUFβ8), were both down-regulated after one week of CAM treatment. However, with AAN progression, NDUFβ8 level restored, while COX-І level maintained low. Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), master regulator of mitochondrial biogenesis, was significantly down-regulated at week 4 and week 8, but significantly up-regulated at week 12. In addition, mtDNA copy number reduced markedly along with AAN progression.

DISCUSSION AND CONCLUSION

A rat model of chronic AAN was successfully reproduced by gavage with CAM extract. Dynamic changes of mitochondrial injury induced by CAM might contribute to the AAN progression.

Peroxisome Proliferator-Activated Receptor Ligands and Their Role in Chronic Myeloid Leukemia: Therapeutic Strategies

Imatinib therapy remains the gold standard for treatment of chronic myeloid leukemia; however, the acquired resistance to this therapeutic agent in patients has urged the scientists to devise modalities for overcoming this chemoresistance. For this purpose, initially therapeutic agents with higher tyrosine kinase activity were introduced, which had the potential for inhibiting even mutant forms of Bcr-Abl. Furthermore, coupling imatinib with peroxisome proliferator-activated receptor ligands also showed beneficial effects in chronic myeloid leukemia cell proliferation. These combination protocols inhibited cell growth and induced apoptosis as well as differentiation in chronic myeloid leukemia cell lines. In addition, peroxisome proliferator-activated receptors ligands increased imatinib uptake by upregulating the expression of human organic cation transporter 1. Taken together, peroxisome proliferator-activated receptors ligands are currently being considered as novel promising therapeutic candidates for chronic myeloid leukemia treatment, because they can synergistically enhance the efficacy of imatinib. In this article, we reviewed the potential of peroxisome proliferator-activated receptors ligands for use in chronic myeloid leukemia treatment. The mechanism of action of these therapeutics modalities are also presented in detail.

Inhibitory Effect of Bridged Nucleosides on Thermus aquaticus DNA Polymerase and Insight into the Binding Interactions

Modified nucleosides have the potential to inhibit DNA polymerases for the treatment of viral infections and cancer. With the hope of developing potent drug candidates by the modification of the 2’,4’-position of the ribose with the inclusion of a bridge, efforts were focused on the inhibition of Taq DNA polymerase using quantitative real time PCR, and the results revealed the significant inhibitory effects of 2’,4’-bridged thymidine nucleoside on the polymerase. Study on the mode of inhibition revealed the competitive mechanism with which the 2’,4’-bridged thymidine operates. With a K_i value of 9.7 ± 1.1 μM, the 2’,4’-bridged thymidine proved to be a very promising inhibitor. Additionally, docking analysis showed that all the nucleosides including 2’,4’-bridged thymidine were able to dock in the active site, indicating that the substrate analogs reflect a structural complementarity to the enzyme active site. The analysis also provided evidence that Asp610 was a key binding site for 2’,4’-bridged thymidine. Molecular dynamics (MD) simulations were performed to further understand the conformational variations of the binding. The root-mean-square deviation (RMSD) values for the peptide backbone of the enzyme and the nitrogenous base of the inhibitor stabilized within 0.8 and 0.2 ns, respectively. Furthermore, the MD analysis indicates substantial conformational change in the ligand (inhibitor) as the nitrogenous base rotated anticlockwise with respect to the sugar moiety, complemented by the formation of several new hydrogen bonds where Arg587 served as a pivot axis for binding formation. In conclusion, the active site inhibition of Taq DNA polymerase by 2’,4’-bridged thymidine suggests the potential of bridged nucleosides as drug candidates.

Alpinetin inhibits lung cancer progression and elevates sensitization drug-resistant lung cancer cells to cis-diammined dichloridoplatium

OBJECTIVE

Alpinetin is a novel flavonoid that has demonstrated potent antitumor activity in previous studies. However, the efficacy and mechanism of alpinetin in treating lung cancer have not been determined.

METHODS

We evaluated the impact of different doses and durations of alpinetin treatment on the cell proliferation, the apoptosis of lung cancer cells, as well as the drug-resistant lung cancer cells.

RESULTS

This study showed that the alpinetin inhibited the cell proliferation, enhanced the apoptosis, and inhibited the PI3K/Akt signaling in lung cancer cells. Moreover, alpinetin significantly increased the sensitivity of drug-resistant lung cancer cells to the chemotherapeutic effect of cis-diammined dichloridoplatium. Taken together, this study demonstrated that alpinetin significantly suppressed the development of human lung cancer possibly by influencing mitochondria and the PI3K/Akt signaling pathway and sensitized drug-resistant lung cancer cells.

CONCLUSION

Alpinetin may be used as a potential compound for combinatorial therapy or as a complement to other chemotherapeutic agents when multiple lines of treatments have failed to reduce lung cancer.

Effects of mid-respiratory chain inhibition on mitochondrial function in vitro and in vivo

Schematic showing the toxicological and adaptive effects of drug-induced respiratory chain inhibition in vivo; also highlighting unanticipated differences from observations made in vitro (in red).

Relating the in vitro mitochondrial effects of drug candidates to likely in vivo outcomes remains challenging. Better understanding of this relationship, alongside improved methods to assess mitochondrial dysfunction in vivo, would both guide safer drug candidate selection and better support discovery programmes targeting mitochondria for pharmacological intervention. The aim of this study was to profile the in vivo effects of a compound with suspected complex III electron transport chain (ETC) inhibitory activity (GSK932121A) at doses associated with clinical signs, and relate findings back to in vitro data with the same compound. Control liver mitochondria or HepG2 cells were treated in vitro with GSK932121A to assess mitochondrial effects on both calcium retention capacity (CRC) and oxygen consumption rate (OCR) respectively. The same assessments were then performed on liver mitochondria isolated from Crl:CD(SD) rats, 5 hours following intraperitoneal (IP) administration of GSK932121A. Lactate/pyruvate assessment, hepatic microscopy, blood gas analysis, glutathione profiling and transcriptomics were used to characterise the acute toxicity. In vivo, GSK932121A caused hypothermia, increased levels of hepatocellular oxidative stress and a metabolic shift in energy production, resulting in an increased lactate/pyruvate ratio, liver steatosis and glycogen depletion, together with gene expression changes indicative of a fasted state. As would be expected of an ETC inhibitor, GSK932121A reduced the CRC of liver mitochondria isolated from naive control animals and the OCR of HepG2 cells when treated directly in vitro. In contrast, mitochondria isolated from animals treated with GSK932121A in vivo unexpectedly showed an increase in CRC and basal OCR. Whilst seemingly contradictory, these differences likely reflect an adapted state in vivo resulting from the initial insult in combination with compensatory changes made by the tissue to maintain energy production. Only the initial, unconfounded, response is observable in vitro. These findings improve current understanding of the toxicological and molecular consequences of ETC inhibition. Furthermore, this work highlights key differences in the way that mitochondrial perturbation is manifest in vivo versus in vitro in terms of functional endpoints and helps guide endpoint selection for future studies with potential mitochondrial toxicants or drugs designed to modulate mitochondrial function for therapeutic benefit.

The Aging Heart

Aging results in progressive deteriorations in the structure and function of the heart and is a dominant risk factor for cardiovascular diseases, the leading cause of death in Western populations. Although the phenotypes of cardiac aging have been well characterized, the molecular mechanisms of cardiac aging are just beginning to be revealed. With the continuously growing elderly population, there is a great need for interventions in cardiac aging. This article will provide an overview of the phenotypic changes of cardiac aging, the molecular mechanisms underlying these changes, and will present some of the recent advances in the development of interventions to delay or reverse cardiac aging.

Mitochondria as targets of drug toxicity: Lessons from the R118 phase I experience

Low Wang et al. report the results of the phase I program for R118 in this issue.(2) R118 was designed as an activator of adenosine monophosphate activated protein kinase (AMPK) to treat claudication. The single ascending dose study in healthy subjects was characterized by an unacceptable number of serious adverse events and substantial risk to the participants. The probable mitochondrial mechanism underlying these adverse events suggests important lessons for future drug development.

Design and synthesis of a mitochondria-targeting carrier for small molecule drugs

A novel mitochondria-targeting carrier QCy7HA was developed. QCy7HA transported the covalently attached doxorubicin (DOX) to mitochondria specifically. The conjugate limited the effects of P-glycoprotein (Pgp) efflux pumps of multidrug-resistant cells on DOX, indicating that diverting drugs to mitochondria is a potential promising method for treatment of drug-resistant cancers.

K(ATP) channels and MPTP are involved in the cardioprotection bestowed by chronic intermittent hypobaric hypoxia in the developing rat

The aim of this study was to explore the mechanism underlying the cardioprotection bestowed by chronic intermittent hypobaric hypoxia (CIHH) against ischemia/reperfusion (I/R) injury in developing rats. Neonatal male rats were subjected to CIHH treatments that simulated an altitude of 3000 m a.s.l. for 28 days (CIHH28) and 42 days (CIHH42), respectively, or no treatment (control). The left ventricular function of isolated hearts was evaluated. The ultra-microstructure, superoxide dismutase (SOD) activity and total anti-oxidation capacity (TAC) of the myocardium were determined. The basic left ventricular function remained unchanged in CIHH rats, except for an increased coronary flow. The recovery of cardiac function from I/R, however, was much better in CIHH rats than in control rats. Compared to control rats, CIHH rats had much higher SOD levels and TAC, and the ultra-microstructure damage to mitochondria was considerably less. The cardiac protection of CIHH was canceled out by glibenclamide, an inhibitor of the ATP-sensitive potassium (K(ATP)) channel, 5-hydroxydecanoate, an inhibitor of mitochondrial K(ATP) (mitoKATP), and atractyloside, an opener of the mitochondrial permeability transition pore (MPTP). To the contrary, diazoxide, an opener of mitoKATP, and cyclosporin A, a blocker of MPTP opening, induced cardioprotection in control rats. These results suggest that CIHH protects the heart against I/R injury in developing rats through opening of the K(ATP) channel and inhibiting of opening of the MPTP.

Effects of Mood Stabilizers on Brain Energy Metabolism in Mice Submitted to an Animal Model of Mania Induced by Paradoxical Sleep Deprivation

There is a body of evidence suggesting that mitochondrial dysfunction is involved in bipolar disorder (BD) pathogenesis. Studies suggest that abnormalities in circadian cycles are involved in the pathophysiology of affective disorders; paradoxical sleep deprivation (PSD) induces hyperlocomotion in mice. Thus, the present study aims to investigate the effects of lithium (Li) and valproate (VPA) in an animal model of mania induced by PSD for 96 h. PSD increased exploratory activity, and mood stabilizers prevented PSD-induced behavioral effects. PSD also induced a significant decrease in the activity of complex II-III in hippocampus and striatum; complex IV activity was decreased in prefrontal cortex, cerebellum, hippocampus, striatum and cerebral cortex. Additionally, VPA administration was able to prevent PSD-induced inhibition of complex II-III and IV activities in prefrontal cortex, cerebellum, hippocampus, striatum and cerebral cortex, whereas Li administration prevented PSD-induced inhibition only in prefrontal cortex and hippocampus. Regarding the enzymes of Krebs cycle, only citrate synthase activity was increased by PSD in prefrontal cortex. We also found a similar effect in creatine kinase, an important enzyme that acts in the buffering of ATP levels in brain; its activity was increased in prefrontal cortex, hippocampus and cerebral cortex. These results are consistent with the connection of mitochondrial dysfunction and hyperactivity in BD and suggest that the present model fulfills adequate face, construct and predictive validity as an animal model of mania.

Hepatotoxicity of piperazine designer drugs: Comparison of different in vitro models

Piperazine derived drugs emerged on the drug market in the last decade. The aim of this study was to investigate in vitro the potential hepatotoxicity of the designer drugs N-benzylpiperazine (BZP), 1-(3-trifluoromethylphenyl)piperazine (TFMPP), 1-(4-methoxyphenyl)piperazine (MeOPP) and 1-(3,4-methylenedioxybenzyl)piperazine (MDBP) in two human hepatic cell lines (HepaRG and HepG2) and in primary rat hepatocytes. Cell death was evaluated by the MTT assay, after 24 h-incubations. Among the tested drugs, TFMPP was the most cytotoxic. HepaRG cells and primary hepatocytes revealed to be the most and the least resistant cellular models, respectively. To ascertain whether the CYP450 metabolism could explain their higher susceptibility, primary hepatocytes were co-incubated with the piperazines and the CYP450 inhibitors metyrapone and quinidine, showing that CYP450-mediated metabolism contributes to the detoxification of these drugs. Additionally, the intracellular contents of reactive species, ATP, reduced (GSH) and oxidized (GSSG) glutathione, changes in mitochondrial membrane potential (Δψm) and caspase-3 activation were further evaluated in primary cells. Overall, an increase in reactive species formation, followed by intracellular GSH and ATP depletion, loss of Δψm and caspase-3 activation was observed for all piperazines, in a concentration-dependent manner. In conclusion, piperazine designer drugs produce hepatic detrimental effects that can vary in magnitude among the different analogues.

Se-Methylselenocysteine Inhibits Apoptosis Induced by Clusterin Knockdown in Neuroblastoma N2a and SH-SY5Y Cell Lines

Apoptosis, as a programmed cell death process, is essential for the maintenance of tissue function in organisms. Alteration of this process is linked to many diseases. Over-expression of clusterin (Clu) can antagonize apoptosis in various cells. Selenium (Se) is an essential trace element for human health. Its biological function is also associated with cell apoptosis. To explore the function of Clu and the impact of Se in the process of apoptosis, several short-hairpin RNAs (shRNA) were designed for the construction of two sets of recombinant plasmids: one set for plasmid-transfection of mouse neuroblastoma N2a cells (N2a cells); and the other set for lentiviral infection of human neuroblastoma SH-SY5Y cells (SH-SY5Y cells). These shRNAs specifically and efficiently interfered with the intracellular expression of Clu at both the mRNA and protein levels. The Clu-knockdown cells showed apoptosis-related features, including down-regulation of antioxidative capacity and the Bcl-2/Bax ratio and up-regulation of caspase-8 activity. Se-methylselenocysteine (MSC) at an optimum concentration of 1 μM could reverse the alteration in antioxidative capacity, Bcl2/Bax ratio and caspase-8 activity caused by Clu-knockdown, thus inhibiting apoptosis and maintaining cell viability. The results hereby imply the potentiality of Clu and Se in neuroprotection.

3-Bromopyruvate induces apoptosis in breast cancer cells by downregulating Mcl-1 through the PI3K/Akt signaling pathway

The hexokinase inhibitor 3-bromopyruvate (3-BrPA) can inhibit glycolysis in tumor cells to reduce ATP production, resulting in apoptosis. However, as 3-BrPA is an alkylating agent, its cytotoxic action may be induced by other molecular mechanisms. The results presented here reveal that 3-BrPA-induced apoptosis is caspase independent. Further, 3-BrPA induces the generation of reactive oxygen species in MDA-MB-231 cells, leading to mitochondria-mediated apoptosis. These results suggest that caspase-independent apoptosis may be induced by the generation of reactive oxygen species. In this study, we also demonstrated that 3-BrPA induces apoptosis through the downregulation of myeloid cell leukemia-1 (Mcl-1) in MDA-MB-231 breast cancer cells. The results of Mcl-1 knockdown indicate that Mcl-1 plays an important role in 3-BrPA-induced apoptosis. Further, the upregulation of Mcl-1 expression in 3-BrPA-treated MDA-MB-231 cells significantly increases cell viability. In addition, 3-BrPA treatment resulted in the downregulation of p-Akt, suggesting that 3-BrPA may downregulate Mcl-1 through the phosphoinositide-3-kinase/Akt pathway. These findings indicate that 3-BrPA induces apoptosis in breast cancer cells by downregulating Mcl-1 through the phosphoinositide-3-kinase/Akt signaling pathway.

Effect of 7-Nitroindazole, a Neuronal Nitric Oxide Synthase Inhibitor, on Behavioral and Physiological Parameters

The role of brain derived nitric oxide in the physiology and behavior remains disputable. One of the reasons of the controversies might be systemic side effects of nitric oxide synthase inhibitors. Therefore, under nNOS inhibition by 7-nitroindazole (7-NI) we carried out recordings of blood gasses, blood pressure and spontaneous EEG in conscious adult rats. Locomotion and spontaneous behavior were assessed in an open field. In addition skilled walking and limb coordination were evaluated using a ladder rung walking test. The blood gas analysis revealed a significant increase in pCO2 180 min and 240 min after the application of 7-NI. The power and entropy decreased simultaneously with a shift of the mean frequency of the spontaneous EEG toward slow oscillations after 7-NI treatment. The thresholds of evoked potentials underwent a significant drop and a trend towards a slight increase in the I-O curve slope was observed. 7-NI significantly suppressed open field behavior expressed as distance moved, exploratory rearing and grooming. As for the ladder rung walking test the 7-NI treated animals had more errors in foot placement indicating impairment in limb coordination. Therefore our findings suggest that 7-NI increased cortical excitability and altered some physiological and behavioral parameters.

Mitochondria: the gateway for tamoxifen-induced liver injury

Tamoxifen (TAM) is routinely used in the treatment of breast carcinoma. TAM-induced liver injury remains a major concern, as TAM causes hepatic steatosis in a significant number of patients, which can progress toward steatohepatitis. Liver toxicity is generally believed to involve mitochondrial dysfunction and TAM exerts multiple deleterious effects on mitochondria, which may account for the hepatotoxicity observed in patients treated with TAM. Endoxifen (EDX), a key active metabolite of TAM that is being investigated as an alternative to TAM in breast cancer therapy, slightly affects mitochondria in comparison with TAM and this demonstration well correlates with the absence of alterations in the clinical parameters of individuals taking EDX. The steady-state plasma concentrations of TAM and its active metabolites EDX and 4-hydroxytamoxifen (OHTAM) in patients taking TAM are highly variable, reflecting genetic variants of CYP2D6 involved in TAM metabolism. Besides de genetic polymorphisms, the intake of drugs that influence the enzymatic activity of CYP2D6 compromises the therapeutic efficiency of TAM. The knowledge of the impact of the variability of TAM metabolism in the breast cancer treatment explains the discrepant outcomes observed in patients taking TAM, as well as the individual variability of idiosyncratic liver injury and other sides effects observed. Therefore, and contrarily to the clinical use of EDX, the need of therapeutic drug monitoring and a regular assessment of liver function biomarkers should be considered in patients under therapies with TAM. In this review we focus on the mitochondrial effects of TAM and its metabolites and on the role played by mitochondria in the initiating events leading to TAM-induced hepatotoxicity, as well as the clinical implications.

Dissociative Electron Attachment to Anthralin to Model Its Biochemical Reactions

The antipsoriatic drug anthralin (dithranol) is known to be extensively accumulated inside mitochondria of keratinocytes and to interact with the electron flow of the respiratory chain. Primary products of the one-electron reduction of polyphenolic anthralin observed in vivo are its dehydrogenated anions, which are formed by H-atom abstraction. The same species are mainly generated at low electron energies by dissociative electron attachment (DEA) to anthralin molecules in vacuo. A likely mechanism for the biochemical transformations of anthralin under reductive conditions in vivo is hypothesized on the basis of its DEA properties. The involvement of excited electronic states generated by ultraviolet irradiation of skin is discussed.

High-throughput screening of FDA-approved drugs using oxygen biosensor plates reveals secondary mitofunctional effects

Repurposing of FDA-approved drugs with effects on mitochondrial function might shorten the critical path to mitochondrial disease drug development. We improved a biosensor-based assay of mitochondrial O2 consumption, and identified mitofunctional defects in cell models of LHON and FXTAS. Using this platform, we screened a 1600-compound library of clinically used drugs. The assay identified drugs known to affect mitochondrial function, such as metformin and decoquinate. We also identified several drugs not previously known to affect mitochondrial respiration including acarbose, metaraminol, gallamine triethiodide, and acamprosate. These previously unknown 'mitoactives' represent novel links to targets for mitochondrial regulation and potentially therapy, for mitochondrial disease.