Reactive Oxygen Species and Mitochondrial Dynamics: The Yin and Yang of Mitochondrial Dysfunction and Cancer Progression

Phenoxythiophene sulfonamide compound B355252 protects neuronal cells against glutamate-induced excitotoxicity by attenuating mitochondrial fission and the nuclear translocation of AIF

Glutamate neurotoxicity has been implicated in the initiation and progression of various neurological and neurodegenerative disorders. Therefore, it is necessary to develop therapeutics for the treatment of patients with these devastating diseases. Mitochondrial fission plays an import role in the mediation of cell death and survival. The objective of the present study was to determine whether B355252, a phenoxythiophene sulfonamide derivative, reduces glutamate-induced cell death by inhibiting mitochondrial fission and the nuclear translocation of apoptosis-inducing factor (AIF) in glutamate-challenged HT22 neuronal cells. The results revealed that glutamate treatment led to large increases in the mitochondrial levels of the major fission proteins dynamin-related protein 1 (Drp1) and mitochondrial fission 1 protein (Fis1), but only small elevations in the fusion proteins mitofusin 1 and 2 (Mfn1/2) and optic atrophy 1 (Opa1). In addition, glutamate toxicity disrupted mitochondrial reticular networks and increased the translocation of AIF to the nucleus. Pretreatment with B35525 reduced glutamate-induced cell death and prevented the increases in the protein levels of Drp1, Fis1, Mfn1/2 and Opa1 in the mitochondrial fraction. More importantly, the architecture of the mitochondria was protected and nuclear translocation of AIF was completely inhibited by B35525. These findings suggest that the regulation of mitochondrial dynamics is central to the neuroprotective properties of B355252, and presents an attractive opportunity for potential development as a therapy for neurodegenerative disorders associated with mitochondria dysfunction.

Dynamic Changes of Mitochondrial DNA Copy Number in Gastrointestinal Tract Cancers: A Systematic Review and Meta-Analysis

We have performed a systematic review and meta-analysis for evaluation of mitochondrial DNA copy number (mtDNA-CN) alterations in peripheral blood leukocytes (PBL), and tumor tissues of gastrointestinal tract (GIT) cancers. Analysis of the PBL demonstrated a significant decrease [OR: 0.6 (0.5, 0.8)] and increase [OR: 1.4 (1.1, 1.9)] prior to and following GIT cancer development, respectively. This trend was more evident in CRC, and GC subgroups. Analysis of tissue yielded high levels of heterogeneity. However, the mean difference for the CRC subgroup was statistically significant [1.5 (1.0, 2.2)]. Our analysis suggests mtDNA-CN deserves further investigations as a GIT-cancer screening tool.

Antioxidative Effects of Chrysoeriol via Activation of the Nrf2 Signaling Pathway and Modulation of Mitochondrial Function

Retinal pigment epithelium (RPE) cell dysfunction caused by excessive oxidative damage is partly involved in age-related macular degeneration, which is among the leading causes of visual impairment in elderly people. Here, we investigated the protective role of chrysoeriol against hydrogen peroxide (H₂O₂)-induced oxidative stress in RPE cells. The cellular viability, reactive oxygen species (ROS) generation, and mitochondrial function of retinal ARPE-19 cells were monitored under oxidative stress or pre-treatment with chrysoeriol. The expression levels of mitochondrial-related genes and associated transcription factors were assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Moreover, the protein expression of antioxidant signal molecules was characterized by Western blot analysis. Chrysoeriol significantly increased cell viability, reduced ROS generation, and increased the occurrence of antioxidant molecules in H₂O₂-treated ARPE-19 cells. Additionally, mitochondrial dysfunction caused by H₂O₂-induced oxidative stress was also considerably diminished by chrysoeriol treatment, which reduced the mitochondrial membrane potential (MMP) and upregulated mitochondrial-associated genes and proteins. Chrysoeriol also markedly enhanced key transcription factors (Nrf2) and antioxidant-associated genes (particularly HO-1 and NQO-1). Therefore, our study confirms the protective effect of chrysoeriol against H₂O₂-induced oxidative stress in RPE cells, thus confirming that it may prevent mitochondrial dysfunction by upregulating antioxidant-related molecules.

The Impact of Mitochondrial Fission-Stimulated ROS Production on Pro-Apoptotic Chemotherapy

Cancer is one of the world's deadliest afflictions. Despite recent advances in diagnostic and surgical technologies, as well as improved treatments of some individual tumor types, there is currently no universal cure to prevent or impede the uncontrolled proliferation of malignant cells. Targeting tumors by inducing apoptosis is one of the pillars of cancer treatment. Changes in mitochondrial morphology precede intrinsic apoptosis, but mitochondrial dynamics has only recently been recognized as a viable pharmacological target. In many cancers, oncogenic transformation is accompanied by accumulation of elevated cellular levels of ROS leading to redox imbalance. Hence, a common chemotherapeutic strategy against such tumor types involves deploying pro-oxidant agents to increase ROS levels above an apoptotic death-inducing threshold. The aim of this chapter is to investigate the benefit of stimulating mitochondrial fission-dependent production of ROS for enhanced killing of solid tumors. The main question to be addressed is whether a sudden and abrupt change in mitochondrial shape toward the fragmented phenotype can be pharmacologically harnessed to trigger a burst of mitochondrial ROS sufficient to initiate apoptosis specifically in cancer cells but not in non-transformed healthy tissues.

Downregulation of dihydrolipoyl dehydrogenase by UVA suppresses melanoma progression via triggering oxidative stress and altering energy metabolism

Melanoma, the most severe form of skin cancer, has poor prognosis and is resistant to chemotherapy. Targeting cancer metabolism is a promising approach in cancer therapeutics. Dihydrolipoyl dehydrogenase (DLD) is a mitochondrial enzyme with diaphorase activity. Here we report a pivotal role of DLD in melanoma cell progression and proliferation. Suppression DLD expression by low intensity UVA (125 mJ/cm²) increased intracellular ROS production and decreased mitochondrial membrane potential thereby inducing autophagy cell death which were confirmed by increased LC3BII and decreased p62 expression in melanoma cells. Knockdown of DLD in melanoma cells also showed similar results. More so, suppression of DLD significantly inhibits in vivo melanoma growth and tumor proliferation. In addition, suppression of DLD increased the NAD+/NADH ratio in melanoma cells and also inhibits TCA cycle related metabolites. DLD downregulation markedly increased α-ketoglutarate and decreased succinic acid suggesting that DLD suppression may have decreased TCA cycle downstream metabolites, resulting in the alteration of mitochondrial energy metabolism Thus the downregulation of DLD induced autophagic cell death in melanoma cells and inhibits in vivo tumor growth and proliferation by increasing ROS production and altering energy metabolism. Our findings suggest that DLD plays a pivotal role in melanoma progression and proliferation.

Mouse liver is more resistant than skeletal muscle to heat-induced apoptosis

During passive heat stress, shifting of blood flow from the hepato-splanchnic to peripheral regions produces less favorable physiological conditions in the liver than in the skeletal muscle. We were wondering if the two organs differ in susceptibility to heat injury and thus examined the effects of heat shock exposure on apoptotic and heat stress-related markers in the gastrocnemius muscle and liver of mice. During heat exposure, mice had a peak core body temperature of 41.1 ± 0.7 °C. Heat-exposed mice showed higher levels of reactive oxygen species (ROS), cleaved caspases, fragmented DNA, and Drp1 protein expression in the gastrocnemius muscles than control mice. These changes were not observed in the livers of heat-exposed mice. Furthermore, the levels of glucocorticoid receptor, HSP70, and HSF1 proteins were significantly elevated in the gastrocnemius muscles of heat-exposed mice compared with that of control mice. The livers of heat-exposed mice also revealed increased expression of HSP70 but no changes in the other proteins. These results demonstrate that heat exposure induces significantly lower levels of the stress response and apoptosis in the liver than in the skeletal muscle of mice. The liver tissue resistance against heat stress is associated with low levels of heat-induced ROS production and mitochondrial fission protein expression.

HIV TAT-mediated microglial senescence: Role of SIRT3-dependent mitochondrial oxidative stress

The advent of combined antiretroviral treatment (cART) as a treatment for HIV-1 infection has not only resulted in a dramatic decrease in the peripheral viral load but has also led to increased life expectancy of the infected individuals. Paradoxically, increased lifespan is accompanied with higher prevalence of age-related comorbidities, including HIV-associated neurocognitive disorders (HAND). Present study was aimed at exploring the role of HIV TAT protein in mediating microglial mitochondrial oxidative stress, ultimately resulting in neuroinflammation and microglial senescence. Our findings demonstrated that exposure of mouse primary microglial cells (mPMs) to HIV TAT protein resulted in a senescence-like phenotype, that was characterized by elevated expression of both p16 and p21 proteins, increased numbers of senescence-associated-β-galactosidase positive cells, augmented cell-cycle arrest, increased release of proinflammatory cytokines and decreased telomerase activity. Additionally, exposure of mPMs to HIV TAT also resulted downregulation of SIRT3 with a concomitant increase in mitochondrial oxidative stress. Dual luciferase reporter assay identified miR-505 as a novel target of SIRT3, which was upregulated in mPMs exposed to HIV TAT. Furthermore, transient transfection of mPMs with either the SIRT3 plasmid or miRNA-505 inhibitor upregulated the expression of SIRT3 and mitochondrial antioxidant enzymes, with a concomitant decrease in microglial senescence. These in vitro findings were also validated in the prefrontal cortices and striatum of HIV transgenic rats as well as cART-treated HIV-infected individuals. In summary, this study underscores a yet undiscovered novel mechanism(s) underlying HIV TAT-mediated induction of senescence phenotype in microglia, involving the miR-505-SIRT3 axis-mediated induction of mitochondrial oxidative stress.

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HIV TAT induces senescence-like phenotype in microglia.

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HIV TAT decreases SIRT3 with concomitant increase of mitochondrial ROS.

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Overexpression of SIRT3 attenuated HIV TAT-mediated microglial senescence.

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miR-505 negatively regulate SIRT3 expression.

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miR-505 inhibition prevents SIRT3-mediated mitochondria stress and glial senescence.

Empagliflozin restores chronic kidney disease-induced impairment of endothelial regulation of cardiomyocyte relaxation and contraction

Chronic kidney disease (CKD) promotes development of cardiac abnormalities and is highly prevalent in patients with heart failure, particularly in those with preserved ejection fraction. CKD is associated with endothelial dysfunction, however, whether CKD can induce impairment of endothelium-to-cardiomyocyte crosstalk leading to impairment of cardiomyocyte function is not known. The sodium-glucose co-transporter 2 inhibitor, empagliflozin, reduced cardiovascular events in diabetic patients with or without CKD, suggesting its potential as a new treatment for heart failure with preserved ejection fraction. We hypothesized that uremic serum from patients with CKD would impair endothelial control of cardiomyocyte relaxation and contraction, and that empagliflozin would protect against this effect. Using a co-culture system of human cardiac microvascular endothelial cells with adult rat ventricular cardiomyocytes to measure cardiomyocyte relaxation and contraction, we showed that serum from patients with CKD impaired endothelial enhancement of cardiomyocyte function which was rescued by empagliflozin. Exposure to uremic serum reduced human cardiac microvascular endothelial cell nitric oxide bioavailability, and increased mitochondrial reactive oxygen species and 3-nitrotyrosine levels, indicating nitric oxide scavenging by reactive oxygen species. Empagliflozin attenuated uremic serum-induced generation of endothelial mitochondrial reactive oxygen species, leading to restoration of nitric oxide production and endothelium-mediated enhancement of nitric oxide levels in cardiomyocytes, an effect largely independent of sodium-hydrogen exchanger-1. Thus, empagliflozin restores the beneficial effect of cardiac microvascular endothelial cells on cardiomyocyte function by reducing mitochondrial oxidative damage, leading to reduced reactive oxygen species accumulation and increased endothelial nitric oxide bioavailability.

Distinctive Cellular and Metabolic Reprogramming in Porcine Lung Mononuclear Phagocytes Infected With Type 1 PRRSV Strains

Porcine reproductive and respiratory syndrome (PRRS) has an extensive impact on pig production. The causative virus (PRRSV) is divided into two species, PRRSV-1 (European origin) and PRRSV-2 (North American origin). Within PRRSV-1, PRRSV-1.3 strains, such as Lena, are more pathogenic than PRRSV-1.1 strains, such as Flanders 13 (FL13). To date, the molecular interactions of PRRSV with primary lung mononuclear phagocyte (MNP) subtypes, including conventional dendritic cells types 1 (cDC1) and 2 (cDC2), monocyte-derived DCs (moDC), and pulmonary intravascular macrophages (PIM), have not been thoroughly investigated. Here, we analyze the transcriptome profiles of in vivo FL13-infected parenchymal MNP subpopulations and of in vitro FL13- and Lena-infected parenchymal MNP. The cell-specific expression profiles of in vivo sorted cells correlated with their murine counterparts (AM, cDC1, cDC2, moDC) with the exception of PIM. Both in vivo and in vitro, FL13 infection altered the expression of a low number of host genes, and in vitro infection with Lena confirmed the higher ability of this strain to modulate host response. Machine learning (ML) and gene set enrichment analysis (GSEA) unraveled additional relevant genes and pathways modulated by FL13 infection that were not identified by conventional analyses. GSEA increased the cellular pathways enriched in the FL13 data set, but ML allowed a more complete comprehension of functional profiles during FL13 in vitro infection. Data indicates that cellular reprogramming differs upon Lena and FL13 infection and that the latter might keep antiviral and inflammatory macrophage/DC functions silent. Although the slow replication kinetics of FL13 likely contribute to differences in cellular gene expression, the data suggest distinct mechanisms of interaction of the two viruses with the innate immune system during early infection.

The Calcilytic Drug Calhex-231 Ameliorates Vascular Hyporesponsiveness in Traumatic Hemorrhagic Shock by Inhibiting Oxidative Stress and miR-208a-Mediated Mitochondrial Fission

Background

The calcium-sensing receptor (CaSR) plays a fundamental role in extracellular calcium homeostasis in humans. Surprisingly, CaSR is also expressed in nonhomeostatic tissues and is involved in regulating diverse cellular functions. The objective of this study was to determine if Calhex-231 (Cal), a negative modulator of CaSR, may be beneficial in the treatment of traumatic hemorrhagic shock (THS) by improving cardiovascular function and investigated the mechanisms.

Methods

Rats that had been subjected to THS and hypoxia-treated vascular smooth muscle cells (VSMCs) were used in this study. The effects of Cal on cardiovascular function, animal survival, hemodynamics, and vital organ function in THS rats and the relationship to oxidative stress, mitochondrial fusion-fission, and microRNA (miR-208a) were investigated.

Results

Cal significantly improved hemodynamics, elevated blood pressure, increased vital organ blood perfusion and local oxygen supply, and markedly improved the survival outcomes of THS rats. Furthermore, Cal significantly improved vascular reactivity after THS in vivo and in vitro. Cal also restored the THS-induced decrease in myosin light chain (MLC) phosphorylation (the key element for VSMC contraction). Inhibition of MLC phosphorylation antagonized the Cal-induced restoration of vascular reactivity following THS. Cal suppressed oxidative stress in THS rats and hypoxic-VSMCs. Meanwhile, THS induced expression of mitochondrial fission proteins Drp1 and Fis1 and decreased expression of mitochondrial fusion protein Mfn1 in vascular tissues. Cal reduced expression of Drp1 and Fis1. In hypoxic-VSMCs, Cal inhibited mitochondrial fragmentation and preserved mitochondrial morphology. In addition, miR-208a mimic decreased Fis1 expression, and miR-208a inhibitor prevented Cal-induced Fis1 downregulation in hypoxic-VSMCs.

Conclusion

Calhex-231 exhibits outstanding potential for effective therapy of traumatic hemorrhagic shock, and the beneficial effects result from its protection of vascular function via inhibition of oxidative stress and miR-208a-mediated mitochondrial fission.

2'-Hydroxyflavanone prevents LPS-induced inflammatory response and cytotoxicity in murine macrophages

2'-Hydroxyflavanone (2-HF) is a natural flavonoid isolated from citrus fruits. Multiple studies have demonstrated that 2-HF with its anti-proliferative and pro-apoptotic effects prevent the growth of various cancers. Although 2-HF is a well known anti-oxidative and chemopreventive agent, its role as an anti-inflammatory agent is not well established. In this study, we examined the effect of 2-HF on LPS-induced cytotoxicity and inflammatory response in murine RAW 264.7 macrophages. Flow cytometry analysis showed that pre-treatment of RAW 264.7 macrophages with 2-HF significantly prevented LPS-induced macrophage apoptosis. 2-HF also prevented LPS-induced reactive oxygen species (ROS) and nitric oxide (NO) production, lipid peroxidation, and loss of mitochondrial membrane potential in murine macrophages. Most importantly, the release of multiple inflammatory cytokines and chemokines such as eotaxin, IL-2, IL-10, IL-12p40, LIX, IL-15, IL-17, MCP-1, and TNF-α induced by LPS in the macrophages was inhibited by 2-HF. 2-HF also prevented LPS-induced activation of protein kinases p38MAPK and SAPK/JNK. Apart from this, LPS-induced phosphorylation, nuclear translocation, and DNA-binding of the redox transcription factor, NF-κB, was prevented by 2-HF. Our results demonstrate that 2-HF by regulating ROS/MAPK/NF-κB prevents LPS-induced inflammatory response and cytotoxicity in murine macrophages suggesting that the need of potential development of 2-HF as an anti-inflammatory agent to ameliorate various inflammatory complications.

Development and progression of cancer cachexia: Perspectives from bench to bedside

Cancer cachexia (CC) is a devastating syndrome characterized by weight loss, reduced fat mass and muscle mass that affects approximately 80% of cancer patients and is responsible for 22%-30% of cancer-associated deaths. Understanding underlying mechanisms for the development of CC are crucial to advance therapies to treat CC and improve cancer outcomes. CC is a multi-organ syndrome that results in extensive skeletal muscle and adipose tissue wasting; however, CC can impair other organs such as the liver, heart, brain, and bone as well. A considerable amount of CC research focuses on changes that occur within the muscle, but cancer-related impairments in other organ systems are understudied. Furthermore, metabolic changes in organ systems other than muscle may contribute to CC. Therefore, the purpose of this review is to address degenerative mechanisms which occur during CC from a whole-body perspective. Outlining the information known about metabolic changes that occur in response to cancer is necessary to develop and enhance therapies to treat CC. As much of the current evidences in CC are from pre-clinical models we should note the majority of the data reviewed here are from preclinical models.

Oxidative stress and mitochondrial transfer: A new dimension towards ocular diseases

Ocular cells like, retinal pigment epithelium (RPE) is a highly specialized pigmented monolayer of post-mitotic cells, which is located in the posterior segment of the eye between neuro sensory retina and vascular choroid. It functions as a selective barrier and nourishes retinal visual cells. As a result of high-level oxygen consumption of retinal cells, RPE cells are vulnerable to chronic oxidative stress and an increased level of reactive oxygen species (ROS) generated from mitochondria. These oxidative stress and ROS generation in retinal cells lead to RPE degeneration. Various sources including mtDNA damage could be an important factor of oxidative stress in RPE. Gene therapy and mitochondrial transfer studies are emerging fields in ocular disease research. For retinal degenerative diseases stem cell-based transplantation methods are developed from basic research to preclinical and clinical trials. Translational research contributions of gene and cell therapy would be a new strategy to prevent, treat and cure various ocular diseases. This review focuses on the effect of oxidative stress in ocular cell degeneration and recent translational researches on retinal degenerative diseases to cure blindness.

Manoeuvrability and biocompatibility of endodontic tricalcium silicate-based putties

OBJECTIVES

The present study evaluated the indentation depth, storage modulus and biocompatibility of an experimental endodontic putty designed for endodontic perforation repair and direct pulp-capping (NeoPutty). The results were compared with the properties associated with the commercially available EndoSequence BC RRM Putty (ES Putty).

METHODS

Indentation depth was measured by a profilometer following indentation with the 1/4 lb Gilmore needle. Elastic modulus was evaluated using a strain-controlled rheometer. The effects of eluents derived from these two putties were examined on the viability and proliferation of human dental pulp stem cells (hDPSCs) and human periodontal ligament fibroblasts (hPDLFs), before (1 st testing cycle) and after complete setting (2nd testing cycle).

RESULTS

The ES Putty became more difficult to ident and acquired a larger storage modulus after exposure to atmospheric moisture. Biocompatibility results indicated that both putties were relatively more cytotoxic than the bioinert Teflon negative control, but much less cytotoxic than the zinc oxide-eugenol cement negative control. NeoPutty was less cytotoxic than ES putty in the 1st testing cycle, particularly with hDPSCs. Both putties exhibited more favourable cytotoxicity profiles after complete setting.

CONCLUSIONS

NeoPutty has a better window of maneuverability after exposure to atmospheric moisture. From an in vitro cytotoxicity perspective, the NeoPutty may be considered more biocompatible than ES putty.

CLINICAL SIGNIFICANCE

The experimental NeoPutty is biocompatible and is capable of reducing the frustration of shortened shelf life when jar-stored endodontic putties are exposed to atmospheric moisture during repeated opening of the lid for clinical retrieval.

Isoliquiritigenin Reduces LPS-Induced Inflammation by Preventing Mitochondrial Fission in BV-2 Microglial Cells

Excessive microglial cell activation in the brain can lead to the production of various neurotoxic factors (e.g., pro-inflammatory cytokines, nitric oxide) which can, in turn, initiate neurodegenerative processes. Recent research has been reported that mitochondrial dynamics regulate the inflammatory response of lipopolysaccharide (LPS). Isoliquiritigenin (ISL) is a compound found in Glycyrrhizae radix with anti-inflammatory and antioxidant properties. In this study, we investigated the function of ISL on the LPS-induced pro-inflammatory response in BV-2 microglial cells. We showed that ISL reduced the LPS-induced increase in pro-inflammatory mediators (e.g., nitric oxide and pro-inflammatory cytokines) via the inhibition of ERK/p38/NF-κB activation and the generation of reactive oxygen species (ROS). Furthermore, ISL inhibited the excessive mitochondrial fission induced by LPS, regulating mitochondrial ROS generation and pro-inflammatory response by suppressing the calcium/calcineurin pathway to dephosphorylate Drp1 at the serine 637 residue. Interestingly, the ISL pretreatment reduced the number of apoptotic cells and levels of cleaved caspase3/PARP, compared to LPS-treated cells. Our findings suggested that ISL ameliorated the pro-inflammatory response of microglia by inhibiting dephosphorylation of Drp1 (Ser637)-dependent mitochondrial fission. This study provides the first evidence for the effects of ISL against LPS-induced inflammatory response related and its link to mitochondrial fission and the calcium/calcineurin pathway. Consequently, we also identified the protective effects of ISL against LPS-induced microglial apoptosis, highlighting the pharmacological role of ISL in microglial inflammation-mediated neurodegeneration.

Icariin-induced inhibition of SIRT6/NF-κB triggers redox mediated apoptosis and enhances anti-tumor immunity in triple-negative breast cancer

Abnormal activation of the nuclear factor-kappa B (NF-κB) signaling pathway is closely implicated in triple-negative breast cancer growth, metastasis, and tumor immune escape. In this study, the anti-cancer effects of icariin, a natural flavonol glycoside, toward breast cancer cells and the underlying mechanisms were investigated. This investigation showed that icariin selectively inhibited proliferation and triggered apoptosis in breast cancer cells in a concentration- and time-dependent manner, but exhibited little cytotoxicity in normal breast cells. Moreover, icariin induced cell apoptosis via a mitochondria-mediated pathway, as indicated by the upregulated ratio of Bax/Bcl-2 and reactive oxygen species induction. Importantly, icariin impaired the activation of the NF-κB/EMT pathway, as evidenced by upregulation of SIRT6, resulting in inhibition of migration and invasion of breast cancer cells. Additionally, oss-128167, an inhibitor of SIRT6, dramatically attenuated anti-migration and anti-invasion effects of icariin. Transcriptomic analysis verified that impairment of NF-κB led to the selective function of icariin in breast cancer cells. Notably, icariin exhibited a significant tumor growth inhibition and anti-pulmonary metastasis effect in a tumor mouse model of MDA-MB-231 and 4T1 cells by regulating the tumor immunosuppressive microenvironment. Together, these results showed that icariin could effectively trigger apoptosis and inhibit the migration of breast cancer cells via the SIRT6/NF-κB signaling pathway, suggesting that icariin might serve as a potential candidate drug for the treatment of breast cancer.

Endothelial dysfunction in neuroprogressive disorders-causes and suggested treatments

BACKGROUND

Potential routes whereby systemic inflammation, oxidative stress and mitochondrial dysfunction may drive the development of endothelial dysfunction and atherosclerosis, even in an environment of low cholesterol, are examined.

MAIN TEXT

Key molecular players involved in the regulation of endothelial cell function are described, including PECAM-1, VE-cadherin, VEGFRs, SFK, Rho GEF TRIO, RAC-1, ITAM, SHP-2, MAPK/ERK, STAT-3, NF-κB, PI3K/AKT, eNOS, nitric oxide, miRNAs, KLF-4 and KLF-2. The key roles of platelet activation, xanthene oxidase and myeloperoxidase in the genesis of endothelial cell dysfunction and activation are detailed. The following roles of circulating reactive oxygen species (ROS), reactive nitrogen species and pro-inflammatory cytokines in the development of endothelial cell dysfunction are then described: paracrine signalling by circulating hydrogen peroxide, inhibition of eNOS and increased levels of mitochondrial ROS, including compromised mitochondrial dynamics, loss of calcium ion homeostasis and inactivation of SIRT-1-mediated signalling pathways. Next, loss of cellular redox homeostasis is considered, including further aspects of the roles of hydrogen peroxide signalling, the pathological consequences of elevated NF-κB, compromised S-nitrosylation and the development of hypernitrosylation and increased transcription of atherogenic miRNAs. These molecular aspects are then applied to neuroprogressive disorders by considering the following potential generators of endothelial dysfunction and activation in major depressive disorder, bipolar disorder and schizophrenia: NF-κB; platelet activation; atherogenic miRs; myeloperoxidase; xanthene oxidase and uric acid; and inflammation, oxidative stress, nitrosative stress and mitochondrial dysfunction.

CONCLUSIONS

Finally, on the basis of the above molecular mechanisms, details are given of potential treatment options for mitigating endothelial cell dysfunction and activation in neuroprogressive disorders.

Mitochondrial Dynamics: Fission and Fusion in Fate Determination of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are pivotal to tissue homeostasis, repair, and regeneration due to their potential for self-renewal, multilineage differentiation, and immune modulation. Mitochondria are highly dynamic organelles that maintain their morphology via continuous fission and fusion, also known as mitochondrial dynamics. MSCs undergo specific mitochondrial dynamics during proliferation, migration, differentiation, apoptosis, or aging. Emerging evidence suggests that mitochondrial dynamics are key contributors to stem cell fate determination. The coordination of mitochondrial fission and fusion is crucial for cellular function and stress responses, while abnormal fission and/or fusion causes MSC dysfunction. This review focuses on the role of mitochondrial dynamics in MSC commitment under physiological and stress conditions. We highlight mechanistic insights into modulating mitochondrial dynamics and mitochondrial strategies for stem cell-based regenerative medicine. These findings shed light on the contribution of mitochondrial dynamics to MSC fate and MSC-based tissue repair.

A Translational Study of a Silicon Phthalocyanine Substituted with a Histone Deacetylase Inhibitor for Photodynamic Therapy

In this study, we synthesized and characterized a silicon phthalocyanine substituted with 3-hydroxypyridin-2-thione (SiPc-HDACi), designed to be a chemophotodynamic therapy agent acting as a histone deacetylase inhibitor, and we determined its photophysical, photochemical, and photobiological properties. Next, we evaluated its anticancer efficacy on MCF-7, double positive and MDA-MB-231, triple negative breast cancer cell lines, as well as on a healthy human endothelial cell line (HUVEC). Our results indicate that SiPc-HDACi can target nucleoli of cells, effectively inducing apoptosis while promoting cell cycle arrest thanks to its high singlet oxygen yield and its histone deacetylase downregulating properties, suggesting a powerful anticancer effect on breast cancer in vitro. Our further studies will be conducted with primary breast cancer cell culture to give a better insight into the anticancer mechanism of the compound.

Silver Nanotriangles and Chemotherapeutics Synergistically Induce Apoptosis in Glioma Cells via a ROS-Dependent Mitochondrial Pathway

Background

The synergistic effect of nanomaterials and chemotherapeutics provides a novel strategy for the treatment of tumors. Silver nanotriangles (AgNTs) exhibited some unique properties in nanomedicine. Studies on the synergy of silver-based nanomaterials and anti-tumor drugs against gliomas are rare.

Materials and Methods

Chitosan-coated AgNTs were prepared, followed by characterization using transmission electron microscopy, ultraviolet-visible spectroscopy and X-ray diffraction. The anti-glioma effect of cyclophosphamide (CTX), 5-fluorouracil (5-FU), oxaliplatin (OXA), doxorubicin (DOX) or gemcitabine (GEM) combined with AgNTs in different glioma cell lines (U87, U251 and C6) was assessed by the MTT assay to screen out a drug with the most broad-spectrum and strongest synergistic anti-glioma activity. The intracellular reactive oxygen species (ROS) level, mitochondrial membrane potential (MMP) and cell apoptosis were detected by flow cytometry. The possible underlying mechanisms of the synergy were further investigated with ROS scavenger and specific inhibitors of C-jun N-terminal kinase (JNK), p38 and extracellular signal-regulated kinase 1/2 pathways.

Results

The synthesized AgNTs were mainly triangular and truncated triangular with an average edge length of 125 nm. A synergistic anti-glioma effect of AgNTs combined with CTX was not observed, and the synergism between AgNTs and 5-FU was cell type-specific. AgNTs combined with OXA, DOX or GEM displayed synergistic effects in various glioma cell lines, and the combination of AgNTs and GEM showed the strongest synergistic activity. A decrease in cell viability, loss of the MMP and an increase in apoptosis rate induced by this synergy could be significantly attenuated by the ROS scavenger N-acetylcysteine and JNK inhibitor SP600125.

Conclusion

Our results suggested that the combination of AgNTs and GEM possessed broad-spectrum and potent synergistic anti-glioma activity, resulting from cell apoptosis mediated by a ROS-dependent mitochondrial pathway in which JNK might be involved.

Monitoring the Redox Status in Multiple Sclerosis

Worldwide, over 2.2 million people suffer from multiple sclerosis (MS), a multifactorial demyelinating disease of the central nervous system. MS is characterized by a wide range of motor, autonomic, and psychobehavioral symptoms, including depression, anxiety, and dementia. The blood, cerebrospinal fluid, and postmortem brain samples of MS patients provide evidence on the disturbance of reduction-oxidation (redox) homeostasis, such as the alterations of oxidative and antioxidative enzyme activities and the presence of degradation products. This review article discusses the components of redox homeostasis, including reactive chemical species, oxidative enzymes, antioxidative enzymes, and degradation products. The reactive chemical species cover frequently discussed reactive oxygen/nitrogen species, infrequently featured reactive chemicals such as sulfur, carbonyl, halogen, selenium, and nucleophilic species that potentially act as reductive, as well as pro-oxidative stressors. The antioxidative enzyme systems cover the nuclear factor erythroid-2-related factor 2 (NRF2)-Kelch-like ECH-associated protein 1 (KEAP1) signaling pathway. The NRF2 and other transcriptional factors potentially become a biomarker sensitive to the initial phase of oxidative stress. Altered components of the redox homeostasis in MS were discussed in search of a diagnostic, prognostic, predictive, and/or therapeutic biomarker. Finally, monitoring the battery of reactive chemical species, oxidative enzymes, antioxidative enzymes, and degradation products helps to evaluate the redox status of MS patients to expedite the building of personalized treatment plans for the sake of a better quality of life.

Hydrogen peroxide assisted photorelease of an anthraquinone-based ligand from [Ru(2,2'-bipyridine)2(9,10-dioxo-9,10-dihydroanthracen-1-olate)]Cl in aqueous solution

A new class of light-activated ruthenium(ii) complex was designed as a potential blocker of biological functioning, especially for targeting redox reactions within mitochondria under light activation. Based on our concepts the complex [Ru(bipy)2(1-hydroxyanthra-9,10 quinone)]Cl (RU1) was prepared and studied to understand the preliminary reaction mechanisms and its excited state behaviour through a series of stability tests, electrochemistry, UV-Visible kinetics and femtosecond transient absorption spectroscopy experiments. Under white light in the presence of H2O2 two different reactions (fast and slow) appear to take place. The complex loses the quinone-based ligand and a resulting Ru(iii) or Ru(v) species is produced. The complex RU1 shows potential to consume H2O2 from the one carbon metabolism in mitochondria, and hence may cut the energy cycle pathway of tumor cells.

Mitochondrial unfolded protein response, mitophagy and other mitochondrial quality control mechanisms in heart disease and aged heart

Mitochondria are involved in crucial homeostatic processes in the cell: the production of adenosine triphosphate and reactive oxygen species, and the release of pro-apoptotic molecules. Thus, cell survival depends on the maintenance of proper mitochondrial function by mitochondrial quality control. The most important mitochondrial quality control mechanisms are mitochondrial unfolded protein response, mitophagy, biogenesis, and fusion-fission dynamics. This review deals with mitochondrial quality control in heart diseases, especially myocardial infarction and heart failure. Some previous studies have demonstrated that the activation of mitochondrial quality control mechanisms may be beneficial for the heart, while others have shown that it may lead to heart damage. Our aim was to describe the mechanisms by which mitochondrial quality control contributes to heart protection or damage and to provide evidence that may resolve the seemingly contradictory results from the previous studies.

Donepezil provides neuroprotective effects against brain injury and Alzheimer's pathology under conditions of cardiac ischemia/reperfusion injury

Cardiac ischemia/reperfusion (I/R) injury induces brain pathology. Donepezil, a well-known acetylcholine esterase (AChE) inhibitor, has been proven to exert neuroprotective effects against several neurodegenerative diseases. However, the comprehensive mechanism regarding the therapeutic potential of donepezil on the brain under cardiac I/R injury remains obscure. Here, we hypothesized that treatment with donepezil ameliorates brain pathology following cardiac I/R injury by decreasing blood brain barrier (BBB) breakdown, oxidative stress, neuroinflammation, mitochondrial dysfunction, mitochondrial dynamics imbalance, microglial activation, amyloid-beta (Aβ) accumulation, neuronal apoptosis, and dendritic spine loss. Forty-eight adult male Wistar rats were subjected to surgery for cardiac I/R injury. Then, rats were randomly divided into four groups to receive either (1) saline (vehicle group), donepezil 3 mg/kg via intravenously administered (2) before ischemia (pretreatment group), (3) during ischemia (ischemia group), or (4) at the onset of reperfusion (reperfusion group). At the end of cardiac I/R paradigm, the brains were evaluated for BBB breakdown, brain inflammation, oxidative stress, mitochondrial function, mitochondrial dynamics, microglial morphology, Aβ production, neuronal apoptosis, and dendritic spine density. Administration of donepezil at all time points equally showed an attenuation of brain damage in response to cardiac I/R injury, as indicated by increased expression of BBB junction protein, reduced brain inflammation and oxidative stress, improved mitochondrial function and mitochondrial dynamics, and alleviated Aβ accumulation and microglial activation, resulting in protection of neuronal apoptosis and preservation of dendritic spine number. These findings suggest that donepezil potentially protects brain pathology caused by cardiac I/R injury regardless the timing of treatment.

NIX-Mediated Mitophagy Promotes Effector Memory Formation in Antigen-Specific CD8+ T Cells

Autophagy plays a critical role in the maintenance of immunological memory. However, the molecular mechanisms involved in autophagy-regulated effector memory formation in CD8⁺ T cells remain unclear. Here we show that deficiency in NIX-dependent mitophagy leads to metabolic defects in effector memory T cells. Deletion of NIX caused HIF1α accumulation and altered cellular metabolism from long-chain fatty acid to short/branched-chain fatty acid oxidation, thereby compromising ATP synthesis during effector memory formation. Preventing HIF1α accumulation restored long-chain fatty acid metabolism and effector memory formation in antigen-specific CD8⁺ T cells. Our study suggests that NIX-mediated mitophagy is critical for effector memory formation in T cells.

Gupta et al. demonstrate that mitophagy mediated by NIX, a mitochondrial outer membrane protein, plays a critical role in CD8⁺ T cell effector memory formation by regulating mitochondrial superoxide-dependent HIF1α protein accumulation and fatty acid metabolism. These findings elucidate the molecular mechanisms regulating T cell effector memory formation against viruses.

Alpha-Synuclein Aggregates Associated with Mitochondria in Tunnelling Nanotubes

The interaction of α-synuclein with mitochondria in both typical and atypical Parkinson's disease is a critical component of degeneration. The mechanism of cell-to-cell propagation of pathological α-synuclein in synucleinopathies is unclear. Intercellular exchange of mitochondria along tunnelling nanotubes has been described in other diseases, such as cancer; however, its role in synucleinopathies is unknown. Pathological α-synuclein species have been demonstrated previously to move from cell to cell via tunnelling nanotubes. This process was further explored using co-culture and monoculture systems to determine if α-synuclein binds to migrating mitochondria within tunnelling nanotubes. Super-resolution analysis via stimulated emission depletion microscopy showed interaction between α-synuclein with the mitochondrial outer membrane and the presence of alpha-synuclein associated with mitochondria in tunnelling nanotubes between 1321N1, differentiated THP-1 and SH-SY5Y cell types. siRNA knockdown of Miro1, a critical protein-bridging mitochondria to the motor adaptor complex, had no effect on mitochondrial density or α-synuclein association with mitochondria in tunnelling nanotubes. The results show that α-synuclein aggregates associate with mitochondria in intercellular tunnelling nanotubes, suggesting that mitochondria-mediated α-synuclein transfer between cells may contribute to cell-to-cell spread of α-synuclein aggregates and disease propagation.

Epigenetic regulation of miR-29a/miR-30c/DNMT3A axis controls SOD2 and mitochondrial oxidative stress in human mesenchymal stem cells

The use of human mesenchymal stem cells (hMSCs) in clinical applications requires large-scale cell expansion prior to administration. However, the prolonged culture of hMSCs results in cellular senescence, impairing their proliferation and therapeutic potentials. To understand the role of microRNAs (miRNAs) in regulating cellular senescence in hMSCs, we globally depleted miRNAs by silencing the DiGeorge syndrome critical region 8 (DGCR8) gene, an essential component of miRNA biogenesis. DGCR8 knockdown hMSCs exhibited severe proliferation defects and senescence-associated alterations, including increased levels of reactive oxygen species (ROS). Transcriptomic analysis revealed that the antioxidant gene superoxide dismutase 2 (SOD2) was significantly downregulated in DGCR8 knockdown hMSCs. Moreover, we found that DGCR8 silencing in hMSCs resulted in hypermethylation in CpG islands upstream of SOD2. 5-aza-2'-deoxycytidine treatment restored SOD2 expression and ROS levels. We also found that these effects were dependent on the epigenetic regulator DNA methyltransferase 3 alpha (DNMT3A). Using computational and experimental approaches, we demonstrated that DNMT3A expression was regulated by miR-29a-3p and miR-30c-5p. Overexpression of miR-29a-3p and/or miR-30c-5p reduced ROS levels in DGCR8 knockdown hMSCs and rescued proliferation defects, mitochondrial dysfunction, and premature senescence. Our findings provide novel insights into hMSCs senescence regulation by the miR-29a-3p/miR-30c-5p/DNMT3A/SOD2 axis.

Super-efficient in Vivo Two-Photon Photodynamic Therapy with a Gold Nanocluster as a Type I Photosensitizer

Photodynamic therapy (PDT) is a clinically approved, minimally invasive therapeutic technique that can induce the regression of targeted lesions via generating excess cytotoxic reactive oxygen species. However, due to the limited penetration depth of visible excitation light and the intrinsic hypoxia microenvironment of solid tumors, the efficacy of PDT in the treatment of cancer, especially deep-seated or large tumors, is unsatisfactory. Herein, we developed an efficient in vivo PDT system based on a nanomaterial, dihydrolipoic acid coated gold nanocluster (AuNC@DHLA), that combined the advantages of large penetration depth in tissue, extremely high two-photon (TP) absorption cross section (σ₂ ∼ 10⁶ GM), efficient ROS generation, a type I photochemical mechanism, and negligible in vivo toxicity. With AuNC@DHLA as the photosensitizer, highly efficient in vivo TP-PDT has been achieved.

Mitochondrial Dysfunction in Diabetic Cardiomyopathy: The Possible Therapeutic Roles of Phenolic Acids

As the powerhouse of the cells, mitochondria play a very important role in ensuring that cells continue to function. Mitochondrial dysfunction is one of the main factors contributing to the development of cardiomyopathy in diabetes mellitus. In early development of diabetic cardiomyopathy (DCM), patients present with myocardial fibrosis, dysfunctional remodeling and diastolic dysfunction, which later develop into systolic dysfunction and eventually heart failure. Cardiac mitochondrial dysfunction has been implicated in the development and progression of DCM. Thus, it is important to develop novel therapeutics in order to prevent the progression of DCM, especially by targeting mitochondrial dysfunction. To date, a number of studies have reported the potential of phenolic acids in exerting the cardioprotective effect by combating mitochondrial dysfunction, implicating its potential to be adopted in DCM therapies. Therefore, the aim of this review is to provide a concise overview of mitochondrial dysfunction in the development of DCM and the potential role of phenolic acids in combating cardiac mitochondrial dysfunction. Such information can be used for future development of phenolic acids as means of treating DCM by alleviating the cardiac mitochondrial dysfunction.

Tubulin- and ROS-dependent antiproliferative mechanism of a potent analogue of noscapine, N-propargyl noscapine

AIM

To rationally-design, synthesize, characterize, biologically evaluate, and to elucidate the anticancer mechanism of action of a novel analogue of noscapine, N-propargyl noscapine (NPN), as a potential drug candidate against triple-negative breast cancer (TNBC).

MATERIALS AND METHODS

After the synthesis and IR, ¹H, ¹³C NMR and mass spectral characterization of NPN, its antiproliferative efficacy against different cancer cell lines was investigated using Sulforhodamine B assay. Cell cycle progression was analysed using flow cytometry. The drug-tubulin interactions were studied using tryptophan-quenching assay, ANS-binding assay, and colchicine-binding assay. Immunofluorescence imaging was used to examine the effect of NPN on cellular microtubules. Levels of reactive oxygen species (ROS), loss of mitochondrial membrane potential (MMP), and cell death were studied by staining the cells with DCFDA, Rhodamine 123, and acridine orange/ethidium bromide, respectively.

KEY FINDINGS

NPN strongly inhibited the viability (IC₅₀, 1.35 ± 0.2 μM) and clonogenicity (IC₅₀, 0.56 ± 0.06 μM) of the TNBC cell line, MDA-MB-231, with robust G₂/M arrest. In vitro, the drug bound to tubulin and disrupted the latter's structural integrity and promoted colchicine binding to tubulin. NPN triggered an unusual form of microtubule disruption in cells, repressed recovery of cold-depolymerized cellular microtubules and suppressed their dynamicity. These effects on microtubules were facilitated by elevated levels of ROS and loss of MMP.

SIGNIFICANCE

NPN can be explored further as a chemotherapeutic agent against TNBC.

The Venom of Philippine Tarantula (Theraphosidae) Contains Peptides with Pro-Oxidative and Nitrosative-Dependent Cytotoxic Activities against Breast Cancer Cells (MCF-7) In Vitro

Background:

Breast cancer is a multifactorial disease that affects women worldwide. Its progression is likely to be executed by oxidative stress wherein elevated levels of reactive oxygen and nitrogen species drive several breast cancer pathologies. Spider venom contains various pharmacological peptides which exhibit selective activity to abnormal expression of ion channels on cancer cell surface which can confer potent anti-cancer activities against this disease.

Methods:

Venom was extracted from a Philippine tarantula by electrostimulation and fractionated by reverse phase-high performance liquid chromatography (RP-HPLC). Venom fractions were collected and used for in vitro analyses such as cellular toxicity, morphological assessment, and oxidative stress levels.

Results:

The fractionation of crude spider venom generated several peaks which were predominantly detected spectrophotometrically and colorimetrically as peptides. Treatment of MCF-7 cell line of selected spider venom peptides induced production of several endogenous radicals such as hydroxyl radicals (•OH), nitric oxide radicals (•NO), superoxide anion radicals (•O²⁻) and lipid peroxides via malondialdehyde (MDA) reaction, which is comparable with the scavenging effects afforded by 400 µg/mL vitamin E and L-cysteine (p<0.05). Concomitantly, the free radicals produced decrease the mitochondrial membrane potential and metabolic activity as detected by rhodamine 123 and tetrazolium dye respectively (p>0.05). This is manifested by cytotoxicity in MCF-7 cells as seen by increase in membrane blebbing, cellular detachment, caspase activity and nuclear fragmentation.

Conclusion:

These data suggest that the Philippine tarantula venom contains peptide constituents exhibiting pro-oxidative and nitrosative-dependent cytotoxic activities against MCF-7 cells and can indicate mechanistic insights to further explore its potential application as prooxidants in cancer therapy.

Reactive oxygen species (ROS) production in HepG2 cancer cell line through the application of localized alternating magnetic field

Recent studies have shown the potential of magnetic hyperthermia in cancer treatments. However, the underlying mechanisms involved have not been yet fully described. In particular, the cell death related to magnetic hyperthermia observed in cultures incubated with low concentration of magnetic nanoparticles and under a low intensity alternating magnetic field, in which a macroscopic temperature rise is not observed, is still not understood. In the present study, we investigate the production of intracellular Reactive Oxygen Species (ROS) as a mechanism to induce cell death under these conditions. In this study, the production and influence of ROS on the viability of HepG2 human hepatoma cells (used as a model cell line) are analyzed under the application of variable magnetic fields using hyperthermia agents, such as biomimetic magnetic nanoparticles (BMNPs) mediated by magnetosome MamC protein from Magnetococcus marinus MC-1. The results show that intracellular ROS production increases up to ∼90% following upon the exposure of AMF to HepG2 cells containing BMNPs, which could determine the loss of cell viability (up to ∼40% reduction) without a significant rise in temperature. Such ROS production is linked to mitochondrial dysfunction caused by the application of AMF to cells containing BMNPs.

Heme Synthesis Inhibition Blocks Angiogenesis via Mitochondrial Dysfunction

The relationship between heme metabolism and angiogenesis is poorly understood. The final synthesis of heme occurs in mitochondria, where ferrochelatase (FECH) inserts Fe²⁺ into protoporphyrin IX to produce proto-heme IX. We previously showed that FECH inhibition is antiangiogenic in human retinal microvascular endothelial cells (HRECs) and in animal models of ocular neovascularization. In the present study, we sought to understand the mechanism of how FECH and thus heme is involved in endothelial cell function. Mitochondria in endothelial cells had several defects in function after heme inhibition. FECH loss changed the shape and mass of mitochondria and led to significant oxidative stress. Oxidative phosphorylation and mitochondrial Complex IV were decreased in HRECs and in murine retina ex vivo after heme depletion. Supplementation with heme partially rescued phenotypes of FECH blockade. These findings provide an unexpected link between mitochondrial heme metabolism and angiogenesis.

•

Heme synthesis inhibition changes mitochondrial morphology in endothelial cells

•

Loss of heme causes buildup of mitochondrial ROS and depolarized membrane potential

•

Endothelial cells have damaged oxidative phosphorylation and glycolysis on heme loss

•

Damage is due to loss of heme-containing Complex IV, restored by exogenous heme

TGF-β mediates aortic smooth muscle cell senescence in Marfan syndrome

Formation of aortic aneurysms as a consequence of augmented transforming growth factor β (TGF-β) signaling and vascular smooth muscle cell (VSMC) dysfunction is a potentially lethal complication of Marfan syndrome (MFS). Here, we examined VSMC senescence in patients with MFS and explored the potential mechanisms that link VSMC senescence and TGF-β. Tissue was harvested from the ascending aorta of control donors and MFS patients, and VSMCs were isolated. Senescence-associated β-galactosidase (SA-β-gal) activity and expression of senescence-related proteins (p53, p21) were significantly higher in aneurysmal tissue from MFS patients than in healthy aortic tissue from control donors. Compared to control-VSMCs, MFS-VSMCs were larger with higher levels of both SA-β-gal activity and mitochondrial reactive oxygen species (ROS). In addition, TGF-β1 levels were much higher in MFS- than control-VSMCs. TGF-β1 induced VSMC senescence through excessive ROS generation. This effect was suppressed by Mito-tempo, a mitochondria-targeted antioxidant, or SC-514, a NF-κB inhibitor. This suggests TGF-β1 induces VSMC senescence through ROS-mediated activation of NF-κB signaling. It thus appears that a TGF-β1/ROS/NF-κB axis may mediate VSMC senescence and aneurysm formation in MFS patients. This finding could serve as the basis for a novel strategy for treating aortic aneurysm in MFS.

Baicalin, a Potent Inhibitor of NF-κB Signaling Pathway, Enhances Chemosensitivity of Breast Cancer Cells to Docetaxel and Inhibits Tumor Growth and Metastasis Both In Vitro and In Vivo

Objective

The aim of this study is to investigate the anti-cancer activity and sensibilization of baicalin (BA) against breast cancer (BC) cells.

Methods

The anti-proliferation of BA in BC cell lines was evaluated by MTT and colony formation assays. Apoptotic induction of BA was measured by flow cytometry. Wound-healing and transwell assays were exploited to assess migrated and invasive inhibition of BA. Western-blot and immunofluorescence were used to study mechanisms of anti-migration and sensibilization of BA. Anti-tumor and anti-metastasis effects of BA were evaluated in subcutaneous and pulmonary metastasis mouse model of BC cells.

Results

BA significantly suppressed proliferation and induced apoptosis of BC cells in a concentration- and time-dependent manner. Additionally, BA induced cell apoptosis via the mitochondria-mediated pathway, as evidenced by cellular induction of reactive oxygen species and upregulated expression of the Bax/Bcl-2 ratio. The overall expression and nuclear translocation of NF-κB signaling pathway in BC cells were dramatically inhibited by treatment with BA. BA significantly suppressed abilities of migration and invasion in BC cells. Notably, BA sensitized BC cells to docetaxel (DXL) by suppressing the expression of survivin/Bcl-2. BA also retarded tumor growth and triggered apoptosis of tumor cells in a tumor mouse model of 4T1 cells. Furthermore, pulmonary metastasis of BC cells was distinctly suppressed by BA in a tumor mouse model of 4T1 cells.

Conclusion

BA effectively triggered apoptosis, inhibited metastasis, and enhanced chemosensitivity of BC, implying that BA might serve as a promising agent for the treatment of BC.

The distinctive role of tau and amyloid beta in mitochondrial dysfunction through alteration in Mfn2 and Drp1 mRNA Levels: A comparative study in Drosophila melanogaster

Alzheimer's disease (AD) is one of the most common forms of neurodegenerative diseases. Aggregation of Aβ42 and hyperphosphorylated tau are two major hallmarks of AD. Whether different forms of tau (soluble or hyperphosphorylated) or Aβ are the main culprit in the events observed in AD is still under investigation. Here, we examined the effect of wild-type, prone to hyperphosphorylation and hyperphosphorylated tau, and also Aβ42 peptide on the brain antioxidant defense system and two mitochondrial genes, Marf (homologous to human MFN2) and Drp1 involved in mitochondrial dynamics in transgenic Drosophila melanogaster. AD is an age associated disease. Therefore, the activity of antioxidant agents, CAT, SOD, and GSH levels and the mRNA levels of Marf and Drp1 were assessed in different time points of the flies lifespan. Reduction in cognitive function and antioxidant activity was observed in all transgenic flies at any time point. The most and the least effect on the eye phenotype was exerted by hyperphosphorylated tau and Aβ42, respectively. In addition, the most remarkable alteration in Marf and Drp1 mRNA levels was observed in transgenic flies expressing hyperphosphorylated tau when pan neuronal expression of transgenes was applied. However, when the disease causing gene expression was confined to the mushroom body, Marf and Drp1 mRNA levels alteration was more prominent in tau^WT and tau^E14 transgenic flies, respectively. In conclusion, in spite of antioxidant deficiency caused by different types of tau and Aβ42, it seems that tau exerts more toxic effect on the eye phenotype and mitochondrial genes regulation (Marf and Drp1). Moreover, different mechanisms seem to be involved in mitochondrial genes dysregulation when Aβ or various forms of tau are expressed.

ROS regulation of RAS and vulva development in Caenorhabditis elegans

Reactive oxygen species (ROS) are signalling molecules whose study in intact organisms has been hampered by their potential toxicity. This has prevented a full understanding of their role in organismal processes such as development, aging and disease. In Caenorhabditis elegans, the development of the vulva is regulated by a signalling cascade that includes LET-60ras (homologue of mammalian Ras), MPK-1 (ERK1/2) and LIN-1 (an ETS transcription factor). We show that both mitochondrial and cytoplasmic ROS act on a gain-of-function (gf) mutant of the LET-60ras protein through a redox-sensitive cysteine (C118) previously identified in mammals. We show that the prooxidant paraquat as well as isp-1, nuo-6 and sod-2 mutants, which increase mitochondrial ROS, inhibit the activity of LET-60rasgf on vulval development. In contrast, the antioxidant NAC and loss of sod-1, both of which decrease cytoplasmic H202, enhance the activity of LET-60rasgf. CRISPR replacement of C118 with a non-oxidizable serine (C118S) stimulates LET-60rasgf activity, whereas replacement of C118 with aspartate (C118D), which mimics a strongly oxidised cysteine, inhibits LET-60rasgf. These data strongly suggest that C118 is oxidized by cytoplasmic H202 generated from dismutation of mitochondrial and/or cytoplasmic superoxide, and that this oxidation inhibits LET-60ras. This contrasts with results in cultured mammalian cells where it is mostly nitric oxide, which is not found in worms, that oxidizes C118 and activates Ras. Interestingly, PQ, NAC and the C118S mutation do not act on the phosphorylation of MPK-1, suggesting that oxidation of LET-60ras acts on an as yet uncharacterized MPK-1-independent pathway. We also show that elevated cytoplasmic superoxide promotes vulva formation independently of C118 of LET-60ras and downstream of LIN-1. Finally, we uncover a role for the NADPH oxidases (BLI-3 and DUOX-2) and their redox-sensitive activator CED-10rac in stimulating vulva development. Thus, there are at least three genetically separable pathways by which ROS regulates vulval development.

Immunometabolism: new insights and lessons from antigen-directed cellular immune responses

Modulation of immune responses by nutrients is an important area of study in cellular biology and clinical sciences in the context of cancer therapies and anti-pathogen-directed immune responses in health and disease. We review metabolic pathways that influence immune cell function and cellular persistence in chronic infections. We also highlight the role of nutrients in altering the tissue microenvironment with lessons from the tumor microenvironment that shapes the quality and quantity of cellular immune responses. Multiple layers of biological networks, including the nature of nutritional supplements, the genetic background, previous exposures, and gut microbiota status have impact on cellular performance and immune competence against molecularly defined targets. We discuss how immune metabolism determines the differentiation pathway of antigen-specific immune cells and how these insights can be explored to devise better strategies to strengthen anti-pathogen-directed immune responses, while curbing unwanted, non-productive inflammation.

Heat stress induces apoptosis through disruption of dynamic mitochondrial networks in dairy cow mammary epithelial cells

Heat stress-induced reductions in milk yield and the dysfunction of mammary glands are economically important challenges that face the dairy industry, especially during summer. The aim of the present study is to investigate the effects of heat stress on mitochondrial function by using dairy cow mammary epithelial cells (DCMECs) as an in vitro model. Live cell imaging shows that the mitochondria continually change shape through fission and fusion. However, heat stress induces the fragmentation of mitochondria, as well as the decreased of ATP level, membrane potential, and anti-oxidant enzyme activity and the increased of respiratory chain complex I activity. In addition, the cytosolic Ca²⁺ concentration and cytochrome c expression (Cyto-c) were increased after heat stress treatment. Both qRT-PCR and western blot analysis indicate that mitofusin1/2 (Mfn1/2) and optic atrophy protein-1 (Opa-1) are downregulated after heat stress, whereas dynamin-related protein 1 (Drp1) and fission 1 (Fis-1) are upregulated, which explains the observed defect of mitochondrial network dynamics. Accordingly, the present study indicated that heat stress induced the dysfunction of DCMEC through disruption of the normal balance of mitochondrial fission and fusion.

Inhibition of Kv10.1 Channels Sensitizes Mitochondria of Cancer Cells to Antimetabolic Agents

Reprogramming of energy metabolism constitutes one of the hallmarks of cancer and is, therefore, an emerging therapeutic target. We describe here that the potassium channel Kv10.1, which is frequently overexpressed in primary and metastatic cancer, and has been proposed a therapeutic target, participates in metabolic adaptation of cancer cells through regulation of mitochondrial dynamics. We used biochemical and cell biological techniques, live cell imaging and high-resolution microscopy, among other approaches, to study the impact of Kv10.1 on the regulation of mitochondrial stability. Inhibition of Kv10.1 expression or function led to mitochondrial fragmentation, increase in reactive oxygen species and increased autophagy. Cells with endogenous overexpression of Kv10.1 were also more sensitive to mitochondrial metabolism inhibitors than cells with low expression, indicating that they are more dependent on mitochondrial function. Consistently, a combined therapy using functional monoclonal antibodies for Kv10.1 and mitochondrial metabolism inhibitors resulted in enhanced efficacy of the inhibitors. Our data reveal a new mechanism regulated by Kv10.1 in cancer and a novel strategy to overcome drug resistance in cancers with a high expression of Kv10.1.

Biological links between traumatic brain injury and Parkinson's disease

Parkinson's Disease (PD) is a progressive neurodegenerative disorder with no cure. Clinical presentation is characterized by postural instability, resting tremors, and gait problems that result from progressive loss of A9 dopaminergic neurons in the substantia nigra pars compacta. Traumatic brain injury (TBI) has been implicated as a risk factor for several neurodegenerative diseases, but the strongest evidence is linked to development of PD. Mild TBI (mTBI), is the most common and is defined by minimal, if any, loss of consciousness and the absence of significant observable damage to the brain tissue. mTBI is responsible for a 56% higher risk of developing PD in U.S. Veterans and the risk increases with severity of injury. While the mounting evidence from human studies suggests a link between TBI and PD, fundamental questions as to whether TBI nucleates PD pathology or accelerates PD pathology in vulnerable populations remains unanswered. Several promising lines of research point to inflammation, metabolic dysregulation, and protein accumulation as potential mechanisms through which TBI can initiate or accelerate PD. Amyloid precursor protein (APP), alpha synuclein (α-syn), hyper-phosphorylated Tau, and TAR DNA-binding protein 43 (TDP-43), are some of the most frequently reported proteins upregulated following a TBI and are also closely linked to PD. Recently, upregulation of Leucine Rich Repeat Kinase 2 (LRRK2), has been found in the brain of mice following a TBI. Subset of Rab proteins were identified as biological substrates of LRRK2, a protein also extensively linked to late onset PD. Inhibition of LRRK2 was found to be neuroprotective in PD and TBI models. The goal of this review is to survey current literature concerning the mechanistic overlap between TBI and PD with a particular focus on inflammation, metabolic dysregulation, and aforementioned proteins. This review will also cover the application of rodent TBI models to further our understanding of the relationship between TBI and PD.

Structurally Strained Half-Sandwich Iridium(III) Complexes As Highly Potent Anticancer Agents

Six complexes of formula [Ir(η⁵:κ¹-C₅Me₄CH₂py)(C,N)]PF₆, where C₅Me₄CH₂py is 2-((2,3,4,5-tetramethylcyclopentadienyl)methyl)pyridine, and C,N is 2-phenylpyridine (1), 7,8-benzoquinoline (2), 1-phenylisoquinoline (3), 2-(p-tolyl)pyridine (4), 4-chloro-2-phenylquinoline (5), or 2-(2,4-difluorophenyl)pyridine (6), have been synthesized. The cyclopentadienyl ligand bears a tethered pyridine that binds to the metal center, resulting in an Ir(η⁵:κ¹-C₅Me₄CH₂pyN) tether-ring structure, as confirmed by the X-ray crystal structures of 1, 2, 4, 5, and 6. Nontether versions of 1 and 2 were synthesized to aid unambiguous correlation between structure and activity. While nontether complexes are highly potent toward MCF7 cancer cells (similar to cisplatin), complexes bearing the tether-ring structure, 1-6, are exceptionally more potent (1-2 orders of magnitude). Additionally, 1-6 disrupt mitochondrial membrane potential (ΔΨ_m) and induce oxidative stress. Internalization studies strongly correlate intracellular accumulation and anticancer activity in tether and nontether complexes. We present a new class of organo-iridium drug candidates bearing a structural feature that results in a leap in anticancer potency.

Neuroprotective Effects of Phlorotannin-Rich Extract from Brown Seaweed Ecklonia cava on Neuronal PC-12 and SH-SY5Y Cells with Oxidative Stress

Neurodegenerative disorders in the elderly are characterized by gradual loss of memory and cognitive function. Oxidative stress caused by reactive oxygen species is associated with progressive neuronal cell damage and death in Alzheimer's disease, one of the most common neurodegenerative disorders. An edible brown seaweed, Ecklonia cava, contains a variety of biologically active compounds such as phlorotannins. In this study, we comparatively evaluated the total phenolic content, antioxidant capacity, and neuroprotective effects of the phlorotannin-rich extract from E. cava (PEEC). The total phenolic content of PEEC and dieckol was 810.8 mg gallic acid equivalents (GAE)/g and 996.6 mg GAE/g, respectively. Antioxidant capacity of PEEC was 1,233.8 mg vitamin C equivalents (VCE)/g and 392.1 mg VCE/g determined using ABTS and DPPH assays, respectively, while those of dieckol were 2,238.4 mg VCE/g and 817.7 mg VCE/g. High-performance liquid chromatography results revealed 48.08 ± 0.67 mg dieckol/g of PEEC. PEEC had neuroprotective effects in pheochromocytoma (PC-12) and human neuroblastoma (SH-SY5Y) cells against H₂O₂- and AAPH-induced oxidative damage, partly due to reduced intracellular oxidative stress. PEEC treatment inhibited acetylcholinesterase and butyrylcholinesterase in a dose-dependent manner. Taken together, these findings suggest that PEEC is a good source of antioxidants and neuroprotective materials.

The Role of Hydrogen Peroxide and Peroxiredoxins throughout the Cell Cycle

Hydrogen peroxide (H₂O₂) is an oxidizing agent that induces cellular damage at inappropriate concentrations and gives rise to an arrest during cell cycle progression, causing cell death. Recent evidence indicates that H₂O₂ also acts as a promoter for cell cycle progression by oxidizing specific thiol proteins. The intracellular concentration of H₂O₂ is regulated tightly, enabling its use as a cellular signaling molecule while minimizing its potential to cause cellular damage. Peroxiredoxins (Prxs) have peroxidase activity toward H₂O₂, organic hydroperoxides, and peroxynitrite for protecting cells from oxidative stress. They are suggested to work as signaling mediators, allowing the local accumulation of H₂O₂ by inactivating their peroxidase activity uniquely compared with other antioxidant proteins such as catalase and glutathione peroxidase. Given that Prxs are highly sensitive to oxidation by H₂O₂, they act as sensors and transducers of H₂O₂ signaling via transferring their oxidation state to effector proteins. The concentrations of intracellular H₂O₂ increase as the cell cycle progresses from G₁ to mitosis. Here, we summarize the roles of Prxs with regard to the regulation of cell cycle-dependent kinase activity and anaphase-promoting complex/cyclosome in terms of changes in H₂O₂ levels. Protection of the cell from unwanted progression of the cell cycle is suggested to be a role of Prx. We discuss the possible roles of Prxs to control H₂O₂ levels.

Mitophagy in Cardiovascular Diseases

Cardiovascular diseases are one of the leading causes of death. Increasing evidence has shown that pharmacological or genetic targeting of mitochondria can ameliorate each stage of these pathologies, which are strongly associated with mitochondrial dysfunction. Removal of inefficient and dysfunctional mitochondria through the process of mitophagy has been reported to be essential for meeting the energetic requirements and maintaining the biochemical homeostasis of cells. This process is useful for counteracting the negative phenotypic changes that occur during cardiovascular diseases, and understanding the molecular players involved might be crucial for the development of potential therapies. Here, we summarize the current knowledge on mitophagy (and autophagy) mechanisms in the context of heart disease with an important focus on atherosclerosis, ischemic heart disease, cardiomyopathies, heart failure, hypertension, arrhythmia, congenital heart disease and peripheral vascular disease. We aim to provide a complete background on the mechanisms of action of this mitochondrial quality control process in cardiology and in cardiac surgery by also reviewing studies on the use of known compounds able to modulate mitophagy for cardioprotective purposes.

The role of metabolic checkpoint regulators in B cell survival and transformation

In response to mitogenic stimulation, B cells activate different pro-anabolic signaling pathways such as c-Myc- and mTORC1-dependent networks to satisfy the energetic demands of biomass synthesis and proliferation. In order to preserve viability and function, cell growth cannot progress unchecked and must be adjusted according to the availability of nutrients. Nutrient-sensing proteins such as AMPK antagonize mTORC1 activity in response to starvation. If pro-anabolic signaling pathways are aberrantly activated, B cells may lack the metabolic capacity to accommodate their energetic needs, which can lead to cell death. On the other hand, metabolic hyperactivation is a salient feature of cancer cells, suggesting that mechanisms exist, which allow B cells to cope with metabolic stress. The aim of this review is to discuss how B cells respond to a mismatch between energy supply and demand and what the consequences are of metabolic dysregulation in normal and malignant B cells.

Clinico-pathological significance of Drp1 dysregulation and its correlation to apoptosis in oral cancer patients

Dysregulation in mitochondrial dynamics has been associated with several diseases including cancer. Present study assessed the alteration in mitochondrial fission protein (Drp1) in oral epithelial cells collected from clinically confirmed pre-cancer and cancer patients and further correlates it with the cellular apoptosis signaling. Results indicate the ROS accumulation in OSCC patients is accompanied by several changes including increase in mitochondrial mass, expression of mitochondrial fission protein (Drp1) and alteration in apoptotic signaling. The positive co-relation has been observed between the expressions of anti-apoptotic Bcl-2proteinswith mitochondrial fission protein Drp1. Higher mitochondrial fission in oral cancer cells was also correlated with the increased expression of cell cycle marker CyclinD1 indicating highly proliferative stage of oral cancer cells. The clinical correlation can be extended to develop biomarker for diagram and program in oral cancer management.