N-acetyl cysteine enhances imatinib-induced apoptosis of Bcr-Abl+ cells by endothelial nitric oxide synthase-mediated production of nitric oxide

Introduction  Imatinib, a small-molecule inhibitor of the Bcr-Abl kinase, is a successful drug for treating chronic myeloid leukemia (CML). Bcr-Abl kinase stimulates the production of H₂O₂, which in turn activates Abl kinase. We therefore evaluated whether N-acetyl cysteine (NAC), a ROS scavenger improves imatinib efficacy. Materials and methods  Effects of imatinib and NAC either alone or in combination were assessed on Bcr-Abl⁺ cells to measure apoptosis. Role of nitric oxide (NO) in NAC-induced enhanced cytotoxicity was assessed using pharmacological inhibitors and siRNAs of nitric oxide synthase isoforms. We report that imatinib-induced apoptosis of imatinib-resistant and imatinib-sensitive Bcr-Abl⁺ CML cell lines and primary cells from CML patients is significantly enhanced by co-treatment with NAC compared to imatinib treatment alone. In contrast, another ROS scavenger glutathione reversed imatinib-mediated killing. NAC-mediated enhanced killing correlated with cleavage of caspases, PARP and up-regulation and down regulation of pro- and anti-apoptotic family of proteins, respectively. Co-treatment with NAC leads to enhanced production of nitric oxide (NO) by endothelial nitric oxide synthase (eNOS). Involvement of eNOS dependent NO in NAC-mediated enhancement of imatinib-induced cell death was confirmed by nitric oxide synthase (NOS) specific pharmacological inhibitors and siRNAs. Indeed, NO donor sodium nitroprusside (SNP) also enhanced imatinib-mediated apoptosis of Bcr-Abl⁺ cells. Conclusion  NAC enhances imatinib-induced apoptosis of Bcr-Abl⁺ cells by endothelial nitric oxide synthase-mediated production of nitric oxide.     

Effect of ghrelin on chronic liver injury and fibrogenesis in male rats: Possible role of nitric oxide

Recent studies have revealed that ghrelin may be an antioxidant and anti-inflammatory agent in many organs, however its role in chronic liver injury (CLI) remains unclear. The role of nitric oxide (NO) in CLI is controversial as evidence suggests that NO is either a primary mediator of liver cell injury or exhibits a protective effect against injurious stimuli. Recent evidence demonstrated that the therapeutic potential for ghrelin was through eNOS activation and increase in NO production. However, its role on NO production in the liver has not been previously investigated. The aim of this study was to investigate the role of ghrelin in treatment of CLI, and whether this action is mediated through NO. Forty male rats were divided into four groups: Group I: Control; Group II: chronic liver injury (CLI); Group III: CLI + Ghrelin; and Group IV: CLI + Ghrelin + l-NAME. Liver enzymes and tumor necrosis factor alpha (TNF-α), were measured to assess hepatocellular injury. Liver tissue collagen content, malondialdehyde (MDA), gene expression of Bax, Bcl-2, and eNOS were assessed to determine the mechanism of ghrelin action. Results showed that ghrelin decreased serum liver enzymes and TNF-α levels. Ghrelin also reduced liver tissue collagen, MDA, and Bax gene expression, and increased Bcl-2 and eNOS gene expression. The effects on TNF-α, collagen, MDA, Bax, and eNOS were partially reversed in Group IV, suggesting that ghrelin's action could be through modulation of NO levels. Therefore, ghrelin's hepatoprotective effect is partially mediated by NO release.     

Bax is essential for Drp1‐mediated mitochondrial fission but not for mitochondrial outer membrane permeabilization caused by photodynamic therapy

Bcl‐2 family proteins are critical for the regulation of apoptosis, with the pro‐apoptotic members Bax essential for the release of cytochrome c from mitochondria in many instances. However, we found that Bax was activated after mitochondrial depolarization and the completion of cytochrome c release induced by photodynamic therapy (PDT) with the photosensitizer Photofrin in human lung adenocarcinoma cells (ASTC‐a‐1). Besides, knockdown of Bax expression by gene silencing had no effect on mitochondrial depolarization and cytochrome c release, indicating that Bax makes no contribution to mitochondrial outer membrane permeabilization (MOMP) following PDT. Further study revealed that Bax knockdown only slowed down the speed of cell death induced by PDT, indicating that Bax is not essential for PDT‐induced apoptosis. The fact that Bax knockdown totally inhibited the mitochondrial accumulation of dynamin‐related protein (Drp1) and Drp1 knockdown attenuated cell apoptosis suggest that Bax can promote PDT‐induced apoptosis through promoting Drp1 activation. Besides, Drp1 knockdown also failed to inhibit PDT‐induced cell death finally, indicating that Bax‐mediated Drp1's mitochondrial translocation is not essential for PDT‐induced cell apoptosis. On the other hand, we found that protein kinase Cδ (PKCδ), Bim L and glycogen synthase kinase 3β (GSK3β) were activated upon PDT treatment and might contribute to the activation of Bax under the condition. Taken together, Bax activation is not essential for MOMP but essential for Drp1‐mediated mitochondrial fission during the apoptosis caused by Photofrin‐PDT. J. Cell. Physiol. 226: 530–541, 2011. © 2010 Wiley‐Liss, Inc.     

MIM through MOM: the awakening of Bax and Bak pores

The mechanism whereby mitochondrial DNA (mtDNA) is released into the cytosol and activates the cGAS/STING inflammatory pathway during Bax/Bax‐mediated apoptosis is unknown. In this issue, Riley et al ( 2018 ) report that widening of Bax and Bak pores on the mitochondrial outer membrane (MOM) during apoptosis allows the extrusion of the mitochondrial inner membrane (MIM) into the cytosol and its permeabilization to release mtDNA independently of caspases. In this scenario, Bax and Bak emerge as key modulators of the apoptotic immunogenic response.     

Estradiol-induced protection against ischemia-induced heart mitochondrial damage and caspase activation is mediated by protein kinase G

We have previously reported that estradiol can protect heart mitochondria from the ischemia-induced mitochondrial permeability transition pore-related release of cytochrome c and subsequent apoptosis. In this study we investigated whether the effect of 17-beta-estradiol on ischemia-induced mitochondrial dysfunctions and apoptosis is mediated by activation of signaling protein kinases in a Langendorff-perfused rat heart model of stop-flow ischemia. We found that pre-perfusion of non-ischemic hearts with 100 nM estradiol increased the resistance of subsequently isolated mitochondria to the calcium-induced opening of mitochondrial permeability transition pore and this was mediated by protein kinase G. Loading of the hearts with estradiol prevented ischemia-induced loss of cytochrome c from mitochondria and respiratory inhibition and these effects were reversed in the presence of the inhibitor of Akt kinase, NO synthase inhibitor L-NAME, guanylyl cyclase inhibitor ODQ and protein kinase G inhibitor KT5823. Estradiol prevented ischemia-induced activation of caspases and this was also reversed by KT5823. These findings suggest that estradiol may protect the heart against ischemia-induced injury activating the signaling cascade which involves Akt kinase, NO synthase, guanylyl cyclase and protein kinase G, and results in blockage of mitochondrial permeability transition pore-induced release of cytochrome c from mitochondria, respiratory inhibition and activation of caspases.     

Neuroprotective effect of aspirin combined with ginkgolide injection on cerebral ischemic stroke rats and its effect on ERK12 signal pathway

The main aim of this study was to evaluate the neuroprotective effect of aspirin combined with ginkgolide injection on cerebral ischemic stroke model rats and its effect on extracellular regulated protein kinase 1/2 (REK1/2) signaling pathway, and to clarify the possible mechanism of aspirin combined with ginkgolide injection on neuroprotective mechanism. Experimental rats were randomly divided into sham group, model group, aspirin group, ginkgolide group and combination group (aspirin + ginkgolide injection) (n = 20). The results revealed scores of neurological dysfunction and infarct volume in aspirin group, ginkgolide group and combination group rats were lower than those in model group (P < 0.05). Score of neurological dysfunction and the volume of cerebral infarction in combination group rats were lower than those in aspirin group and ginkgolide group (P < 0.05). Combination of aspirin and ginkgolide injection could better reduce brain water content, reduce apoptosis rate of cortical cells P < 0.05, reduce expression levels of caspase-3, Bax and p-REK1/2 proteins in ischemic brain tissue P < 0.05, and increase expression level of Bcl-2 protein than aspirin and ginkgolide injection alone P < 0.05). In conclusion, the synergistic neuroprotective effect of aspirin and ginkgolide injection on cerebral ischemic stroke rats is better than that of aspirin and ginkgolide injection alone. The mechanism of action may be that the two compounds can play a synergistic role and inhibit the activation of REK1/2 signaling pathway, thus inhibiting apoptosis of nerve cells and exerting neuroprotective effect.     

Induction of mitochondrial biogenesis protects against caspase-dependent and caspase-independent apoptosis in L6 myoblasts

Apoptotic signaling plays an important role in skeletal muscle degradation, atrophy, and dysfunction. Mitochondria are central executers of apoptosis by directly participating in caspase-dependent and caspase-independent cell death signaling. Given the important apoptotic role of mitochondria, altering mitochondrial content could influence apoptosis. Therefore, we examined the direct effect of modest, but physiological increases in mitochondrial biogenesis and content on skeletal muscle apoptosis using a cell culture approach. Treatment of L6 myoblasts with SNAP or AICAR (5 h/day for 5 days) significantly increased PGC-1, AIF, cytochrome c, and MnSOD protein content as well as MitoTracker staining. Following induction of mitochondrial biogenesis, L6 myoblasts displayed decreased sensitivity to apoptotic cell death as well as reduced caspase-3 and caspase-9 activation following exposure to staurosporine (STS) and C2-ceramide. L6 myoblasts with higher mitochondrial content also exhibited reduced apoptosis and AIF release following exposure to hydrogen peroxide (H₂O₂). Analysis of several key apoptosis regulatory proteins (ARC, Bax, Bcl-2, XIAP), antioxidant proteins (catalase, MnSOD, CuZnSOD), and reactive oxygen species (ROS) measures (DCF and MitoSOX fluorescence) revealed that these mechanisms were not responsible for the observed cellular protection. However, myoblasts with higher mitochondrial content were less sensitive to Ca^2 +-induced mitochondrial permeability transition pore formation (mPTP) and mitochondrial membrane depolarization. Collectively, these data demonstrate that increased mitochondrial content at physiological levels provides protection against apoptotic cell death by decreasing caspase-dependent and caspase-independent signaling through influencing mitochondrial Ca^2 +-mediated apoptotic events. Therefore, increasing mitochondrial biogenesis/content may represent a potential therapeutic approach in skeletal muscle disorders displaying increased apoptosis.     

Necrostatin-1 reverts shikonin-induced necroptosis to apoptosis

Degterev et al. previously demonstrated that death receptor mediated apoptosis could be diverted to necroptosis when apoptosis signaling was blocked, suggesting that necroptosis may function as a backup mechanism to insure the elimination of damaged cells under certain conditions when apoptosis was inhibited. Here, we show that shikonin-induced necroptosis can be reverted to apoptosis in the presence of necrostatin-1 (Nec-1), a specific necroptosis inhibitor and that the death mode switch is at least partially due to the conversion from mitochondrial inner membrane permeability to mitochondrial outer membrane permeability, which is associated with Bax translocation. The data combined with the previous reports support a notion that apoptosis and necroptosis may function as reciprocal backup mechanisms of cellular demise. To the best of our knowledge, this is the first study to document a conversion from necroptosis to apoptosis. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

LPS/IFN-γ-Induced RAW 264.7 Apoptosis is Regulated by Both Nitric Oxide–Dependent and –Independent Pathways Involving JNK and the Bcl-2 Family

Lipopolysaccharide (LPS) and interferon-gamma (IFN-γ) stimulate macrophages to produce nitric oxide (NO) via inducible nitric oxide synthase (iNOS) and activate stress signaling cascades including the c-jun-N-terminal kinase (JNK) pathway. These events trigger an apoptotic cascade that ultimately results in death. Since JNK regulates pro-apoptotic and anti-apoptotic Bcl-2 family members, the role of NO in LPS/IFN-γ-induced activation of JNK and its effects on the Bcl-2 family was examined in RAW 264.7 macrophage-like cells. Inhibition of JNK by siRNA verified a role for JNK in LPS/IFN-γ-induced apoptosis. Suppression of NO production by a pharmacologic agent, i.e. iNOS inhibitor L-NIL, altered the kinetics of JNK activation by LPS/IFN-γ. Examination of mitochondrial and nuclear compartments of RAW 264.7 cells demonstrated NO-dependent activation of mitochondrial JNK by LPS/IFN-γ, but NO-independent, cytokine-induced phosphorylation of Bim. NO did not affect phosphorylation, but did inhibit Bax phosphorylation. These results suggest a novel mechanism of LPS/IFN-γ-induced apoptosis in macrophages involving NO-independent phosphorylation of Bim and NO-dependent dephosphorylation of Bax.     

Sustained nitric oxide delivery delays nitric oxide-dependent apoptosis in macrophages: contribution to the physiological function of activated macrophages

Treatment of the macrophage cell line RAW 264.7 with the short-lived NO donor S-nitrosoglutathione triggers apoptosis through the release of mitochondrial mediators. However, continuous supply of NO by long-lived NO donors protected cells from apoptosis through mechanisms that involved the maintenance or an increase in the levels of the inhibitor of apoptosis proteins (IAPs) cIAP-1, cIAP-2, and xIAP and decreases in the accumulation of p53 and in the levels and targeting of Bax to the mitochondria. As a result of these changes, the activation of caspases 9 and 3 was notably delayed, expanding the time of viability of the macrophages. Moreover, inhibition of NO synthase 2 activity after 8 h of stimulation of RAW 264.7 cells with LPS and IFN-gamma accelerated apoptosis via an increase in the processing and activation of caspases. These data suggest that NO exerts an important role in the autoregulation of apoptosis in macrophages.     

Activation of prolyl hydroxylase‐2 for stabilization of mitochondrial stress along with simultaneous downregulation of HIF‐1α/FASN in ER + breast cancer subtype

The present study was undertaken to inquest the chemical activation of prolyl hydroxylase‐2 for the curtailment of hypoxia‐inducible factor‐1α and fatty acid synthase. It was well documented that hypoxia‐inducible factor‐1α and fatty acid synthase were overexpressed in mammary gland carcinomas. After screening a battery of compounds, BBAP‐2 was retrieved as a potential prolyl hydroxylase‐2 activator and validates its activity using ER + MCF‐7 cell line and n‐methyl‐n‐nitrosourea‐induced rat in vivo model, respectively. BBAP‐2 was palpable for the morphological characteristics of apoptosis along with changes in the mitochondrial intergrity as visualized by acridine orange/ethidium bromide and JC‐1 staining against ER + MCF‐7 cells. BBAP‐2 also arrest the cell cycle of ER + MCF‐7 cells at G2/M phase. Afterward, BBAP‐2 has scrutinized against n‐methyl‐n‐nitrosourea‐induced mammary gland carcinoma in albino Wistar rats. BBAP‐2 restored the morphological architecture when screened through carmine staining, haematoxylin and eosin staining, and scanning electron microscopy. BBAP‐2 also delineated the markers of oxidative stress favourably. The immunoblotting and mRNA expression analysis validated that BBAP‐2 has a potentialty activate the prolyl hydroxylase‐2 with sequential downregulating effect on hypoxia‐inducible factor‐1α and its downstream checkpoint. BBAP‐2 also fostered apoptosis through mitochondrial‐mediated death pathway. The present study elaborates the chemical activation of prolyl hydroxylase‐2 by which the increased expression of HIF‐1α and FASN can be reduced in mammary gland carcinoma.     

T cell activation-induced mitochondrial hyperpolarization is mediated by Ca2+- and redox-dependent production of nitric oxide

Activation, proliferation, or programmed cell death of T lymphocytes is regulated by the mitochondrial transmembrane potential (Deltapsi(m)) through controlling ATP synthesis, production of reactive oxygen intermediates (ROI), and release of cell death-inducing factors. Elevation of Deltapsi(m) or mitochondrial hyperpolarization is an early and reversible event associated with both T cell activation and apoptosis. In the present study, T cell activation signals leading to mitochondrial hyperpolarization were investigated. CD3/CD28 costimulation of human PBL elevated cytoplasmic and mitochondrial Ca(2+) levels, ROI production, and NO production, and elicited mitochondrial hyperpolarization. Although T cell activation-induced Ca(2+) release, ROI levels, and NO production were diminished by inositol 1,4,5-triphosphate receptor antagonist 2-aminoethoxydiphenyl borane, superoxide dismutase mimic manganese (III) tetrakis (4-benzoic acid) porphyrin chloride, spin trap 5-diisopropoxyphosphoryl-5-methyl-1-pyrroline-N-oxide, and NO chelator carboxy-2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide, mitochondrial hyperpolarization was selectively inhibited by carboxy-2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (-85.0 +/- 10.0%; p = 0.008) and, to a lesser extent, by 2-aminoethoxydiphenyl borane. Moreover, NO precursor (Z)-1-[2-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate diethylenetriamine elicited NO and ROI production, Ca(2+) release, transient ATP depletion, and robust mitochondrial hyperpolarization (3.5 +/- 0.8-fold; p = 0.002). Western blot analysis revealed expression of Ca-dependent endothelial NO synthase and neuronal NO synthase isoforms and absence of Ca-independent inducible NO synthase in PBL. CD3/CD28 costimulation or H(2)O(2) elicited severalfold elevations of endothelial NO synthase and neuronal NO synthase expression, as compared with beta-actin. H(2)O(2) also led to moderate mitochondrial hyperpolarization; however, Ca(2+) influx by ionomycin or Ca(2+) release from intracellular stores by thapsigargin alone failed to induce NO synthase expression, NO production, or Deltapsi(m) elevation. The results suggest that T cell activation-induced mitochondrial hyperpolarization is mediated by ROI- and Ca(2+)-dependent NO production.     

Enzymic coupling of acylhydrolase and prostaglandin synthase activities in subcellular fractions from rabbit renal medulla

We have recently shown that mitochondrial and plasma-membrane fractions from kidney medulla possess Ca²⁺-stimulated acylhydrolase and prostaglandin synthase activities. The nature of the enzymic coupling between the Ca²⁺-stimulated arachidonic acid release and its subsequent conversion into prostaglandins was investigated in subcellular fractions from rabbit kidney medulla. Plasma-membrane, mitochondrial and microsomal fractions were found to have similar apparent K_m values for conversion of added exogenous arachidonate into prostaglandins. The rate of prostaglandin biosynthesis (V_max.) from added arachidonic acid in the microsomal fraction was approx. 2-fold higher than in the other subcellular fractions. In contrast, prostaglandin E₂ synthesis from endogenous arachidonate in plasma-membrane and mitochondrial fractions was 3–4-fold higher than in microsomes. Furthermore, Ca²⁺ stimulated endogenous arachidonate deacylation and prostaglandin E₂ generation in the former two fractions but not in microsomes. In mitochondrial or crude plasma-membrane fractions, in which prostaglandin biosynthesis was inhibited with aspirin, arachidonate released from these fractions was converted into prostaglandins by the microsomal prostaglandin synthase. Thus an intracellular prostaglandin generation process that involves inter-fraction transfer of arachidonic acid can operate. Prostaglandin generation by such an inter-fraction process is, however, less efficient than by an intra-fraction process, where arachidonic acid released by mitochondria or crude plasma membranes is converted into prostaglandins by prostaglandin synthase present in the same fraction. This demonstrates the presence of a tight intra-fraction enzymic coupling between Ca²⁺-stimulated acylhydrolase and prostaglandin synthase enzyme systems in both mitochondrial and plasma-membrane fractions.     

Inflammatory neurodegeneration mediated by nitric oxide,glutamate, and mitochondria

In inflammatory, infectious, ischemic, and neurodegenerative pathologies of th central nervous system (CNS) glia become “activated” by inflammatory mediators, and express new proteins such as the inducible isoform of nitric oxide synthase (iNOS). Although these activated glia have beneficial roles, in vitro they potently kill cocultured neurons, and there is increasing evidence that they contribute to pathology in vivo. Nitric oxide (NO) from iNOS appears to be a key mediator of such glial-induced neuronal death. The high sensitivity of neurons to NO is partly due to NO causing inhibition of respiration, rapid glutamate release from both astrocytes and neurons, and subsequent excitotoxic death of the neurons. NO is a potent inhibitor of mitochondrial respiration, due to reversible binding of NO to cytochrome oxidase in competition with oxygen, resulting in inhibition of energy production and sensitization to hypoxia. Activated astrocytes or microglia cause a potent inhibition of respiration in cocultured neurons due to glial NO inhibiting cytochrome oxidase within the neurons, resulting in ATP depletion and glutamate release. In some conditions, glutamate-induced neuronal death can itself be mediated by N-methyl-d-aspartate (NMDA)-receptor activation of the neuronal isoform of NO synthase (nNOS) causing mitochondrial damage. In addition NO can be converted to a number of reactive derivatives such as peroxynitrite, NO₂, N₂O₃, and S-nitrosothiols that can kill cells in part by inhibiting mitochondrial respiration or activation of mitochondrial permeability transition, triggering neuronal apoptosis or necrosis.     

Potent proapoptotic actions of dihydroartemisinin in gemcitabine-resistant A549 cells

Our recent studies have demonstrated the key roles of reactive oxygen species (ROS)-mediated caspase-8- and Bax-dependent apoptotic pathways in dihydroartemisinin (DHA)-induced apoptosis of A549 cells. This report is designed to investigate the proapoptotic mechanisms of DHA in gemcitabine (Gem)-resistant A549 (A549GR) cells. A549GR cells exhibited lower basal antioxidant capacity, higher level of basal ROS and intracellular Fe^2 + than Gem-sensitive A549 (A549) cells. In contrast to the sluggish ROS generation induced by Gem, DHA induced a rapid ROS generation within 30 min. Moreover, Gem induced similar ROS generation in both cell lines, while DHA induced more ROS generation in A549GR cells than in A549 cells. More importantly, after treatment with DHA, A549GR cells showed more potent induction in Bax activation, loss of mitochondrial membrane potential (ΔΨm), caspase activation and apoptosis than A549 cells. Furthermore, NAC pretreatment potently prevented DHA-induced ROS generation and loss of ΔΨm as well as apoptosis, and silencing Bax by shRNA or inhibition of one of caspase-3, -8 and -9 also significantly prevented DHA-induced apoptosis in both cell lines, indicating the key roles of ROS and Bax as well as the caspases. Collectively, DHA presents more potent proapoptotic actions in A549GR cells preferentially over normal A549 cells via ROS-dependent apoptotic pathway, in which Bax and caspases are involved.     

Impact of Swimming Exercise Training on the Effects of Modulation of Mitochondrial Permeability Transition and NOS-1 Activation in Medullary Cardiovascular Neurons of Rats

Physical inactivity can be considered one of the major risk factors related to cardiovascular diseases. There are reasons to believe that the positive effect of exercise training is, to a large extent, mediated by modulation of the nervous control of the circulation system. In our previous studies, we showed that modulation of mitochondrial permeability transition in medullary cardiovascular neurons significantly contributes to the hemodynamic reactions in both the norm and a number of pathological states. In this study, we examined in acute experiments on urethane-anesthetized rats the hemodynamic effects mediated by either modulation of mitochondrial permeability transition in medullary neurons, or activation of neuronal NO synthase (NOS-1) in these neuronal populations after preliminary moderate exercise training (everyday swimming sessions of increased duration carried out for four weeks). It was shown that, after exercise training had been completed, the effects of injections of an inductor of mitochondrial permeability transition pore (MPTP) opening, phenylarsine oxide (PAO, 0.5 to 1.5 nmol), into populations of cardiovascular neurons in the medullary autonomic nuclei (nucl. tractus solitarius and paramedian and lateral reticular nuclei) were less expressed, as compared with those in control (untrained) animals. The data obtained suggest that exercise training can exert a protective action on functional activity of medullary neurons due to the decreased sensitivity of MPTPs to their opening. Injections of an inhibitor of MPTP opening, melatonin (0.7 to 2.1 nmol), into populations of medullary neurons under study in trained rats induced a decrease in the systemic arterial pressure (SAP), in contrast to untrained animals demonstrating mostly hypertensive responses following injections of melatonin into the above nuclei. Injections of an activator of neuronal NO synthase (NOS-1), L-arginine, into the medullary nuclei of swimming-trained rats resulted in more expressed hemodynamic shifts than in control animals, which suggests an increase in the activity of neuronal NO synthase in medullary neurons of such animals.     

Naringin abates adverse effects of cadmium‐mediated hepatotoxicity: An experimental study using HepG2 cells

This study investigated the protective potential of Naringin (NIN) against cadmium chloride (CdCl₂) mediated hepatotoxicity using human hepatocellular carcinoma (HepG2) cells. An optimal concentration of NIN (5 μM) was potent enough to confer cytoprotection against CdCl₂ (50 μM) as was observed by MTT assay. Preconditioning with NIN maintained redox homeostasis, mitochondrial membrane potential, and reduced apoptosis as marked by decrease in the percentage sub‐G₀/G₁ and Annexin V‐FITC/propidium iodide positive cells (apoptotic). NIN pretreatment maintained the levels of protein thiol along with endogenous activities of Superoxide dismutase, Glutathione S‐transferase, and Catalase and lowered lipid peroxidation. Decreased Bax/Bcl2 ratio along with reduced Caspase 3 cleavage and Cytochrome c release indicated that NIN conditioning blocked mitochondrial‐mediated apoptosis. Increased Nrf2 and metallothionein (MT) acted as adaptive response in the presence of cadmium. Thus, the protective mechanism of NIN is attributed to its antioxidant potential which aids in redox homeostasis and prevents CdCl₂ mediated cytotoxicity.     

Adlay hull extracts attenuate β-amyloid-induced neurotoxicity and oxidative stress in PC12 cells through antioxidative,anti-inflammatory,and antiapoptotic activities

Alzheimer's disease (AD) is characterized by accumulation of β-amyloid (Aβ) in senile plaques, contributing to oxidative stress, mitochondrial diseases, and synaptic atrophy, consequently leading to the deterioration of brain function. Adlay (Coix lacryma-jobi L.) is an annual botanical. Here, a 95% ethanol extract of adlay hull (AHEE) was partitioned by ethyl acetate (AHEAE), n-butanol (AHBUE), and water (AHWE), and the effects of these extracts on lipopolysaccharide (LPS)-induced RAW264.7 cells and Aβ-induced PC12 cells, as experimental models of neurotoxicity, were evaluated. The expression of anti-inflammatory and antiapoptosis-related proteins was investigated and AHEE, AHEAE, and AHWE were found to exert anti-inflammatory effects. AHWE exhibited antiapoptotic effects and inhibited inducible nitric oxide synthase expression and nitric oxide production. We investigated the protective effects of AHWE against Aβ-induced neurotoxicity in dPC12 cells and explored the underlying mechanism. Pretreatment with AHWE significantly attenuated cell death and Aβ-mediated increase in B cell lymphoma (Bcl)-2/Bax ratio. AHWE significantly inhibited Aβ and enhanced protein kinase B (Akt) level in dPC12 cells, suggesting that its protective effect against Aβ-induced apoptosis in dPC12 cells was mediated through upregulation of the phosphoinositide 3-kinases (PI3K)/Akt signaling pathway. These extracts and its bioactive compound K36–21 may be potentially useful to treat neurodegenerative disorders.     

Abamectin induces apoptosis and autophagy by inhibiting reactive oxygen species‐mediated PI3K/AKT signaling in MGC803 cells

Abamectin (ABA) is one of the most widely used compounds in agriculture and veterinary medicine. However, the cytotoxicity of ABA in human gastric cells is utterly unknown. In this study, ABA suppressed the proliferation of MGC803 cells by arresting the cell cycle at the G0/G1‐phase. Moreover, ABA induced mitochondrial‐mediated apoptosis by inducing the loss of mitochondrial membrane potential, upregulation of Bax/Bcl‐2, and activation of caspase‐3. ABA significantly improved the LC3‐II/LC3‐I ratio and reduced P62 protein expression in a dose‐dependent manner. Through detection of the reactive oxygen species (ROS) levels, we found ABA induced the accumulation of intracellular ROS and then reduced PI3K/AKT signaling activation related to MGC803 cell apoptosis and autophagy. Our results indicate that ABA exerts cytotoxic effects on human MGC803 cells through apoptosis and autophagy by inhibiting ROS‐mediated PI3K/AKT signaling. Furthermore, ABA may be a potential risk to human gastric health.