Bcl-xL prevents cell death following growth factor withdrawal by facilitating mitochondrial ATP/ADP exchange

Venetoclax resistance in acute myeloid leukaemia-Clinical and biological insights

Venetoclax, an oral BCL-2 inhibitor, has been widely incorporated in the treatment of acute myeloid leukaemia. The combination of hypomethylating agents and venetoclax is the current standard of care for elderly and patient's ineligible for aggressive therapies. However, venetoclax is being increasingly used with aggressive chemotherapy regimens both in the front line and in the relapse setting. Our growing experience and intensive research demonstrate that certain genetic abnormalities are associated with venetoclax sensitivity, while others with resistance, and that resistance can emerge during treatment leading to disease relapse. In the current review, we provide a summary of the known mechanisms of venetoclax cytotoxicity, both regarding the inhibition of BCL-2-mediated apoptosis and its effect on cell metabolism. We describe how these pathways are linked to venetoclax resistance and are associated with specific mutations. Finally, we provide the rationale for novel drug combinations in current and future clinical trials.

Exploring the Bioactive Potential of Calostoma insigne, an Endangered Culinary Puffball Mushroom, from Northeastern Thailand

Calostoma insigne puffball mushrooms are only found in forests with rich biodiversity in very few countries including Thailand, and their biofunctions remain largely unexplored. This study used the agar disk diffusion assay, the anti-glucosidase assay, and the 3, 4, 5-dimethylthiazol-2-yl-2-5-diphenyltetrazolium bromide (MTT) assay to evaluate the bioactive potential of these endangered puffball mushrooms. Internal transcribed spacer (ITS) gene analysis identified C. insigne, a puffball mushroom with green, globose, and spiny spores. Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the polysaccharide structure while scanning electron microscopy (SEM) revealed a fiber-like network. The ethanolic gelatinous fruiting body extract exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH)-scavenging capacity (57.96%), a ferric ion-reducing antioxidant power (FRAP) value of 1.73 mg FeSO4/g, and α-glucosidase inhibition (73.18%). C. insigne cytotoxicity was effective towards HT-29 colon cancer cells using the MTT assay (IC50 of 770.6 µg/mL at 72 h) and also showed antiproliferative capacity (IC50 of 297.1 µg/mL). This puffball mushroom stimulated apoptotic genes and proteins (caspase-3, Bax, and p21) via an intrinsic apoptotic pathway in HT-29 cells. In the laboratory, the medium formula consisting of 20% potato, 2% sucrose, and 0.2% peptone was optimal to increase fungal mycelial biomass (2.74 g DW/100 mL), with propagation at pH 5.0 and 30 °C. Puffball mushrooms are consumed as local foods and also confer several potential health benefits, making them worthy of conservation for sustainable utilization.

ΔNp63 Regulates Radioresistance in Human Head and Neck Squamous Carcinoma Cells

Radiation therapy is commonly used to treat head and neck squamous cell carcinoma (HNSCC); however, recurrence results from the development of radioresistant cancer cells. Therefore, it is necessary to identify the underlying mechanisms of radioresistance in HNSCC. Previously, we showed that the inhibition of karyopherin-β1 (KPNB1), a factor in the nuclear transport system, enhances radiation-induced cytotoxicity, specifically in HNSCC cells, and decreases the localization of SCC-specific transcription factor ΔNp63. This suggests that ΔNp63 may be a KPNB1-carrying nucleoprotein that regulates radioresistance in HNSCC. Here, we determined whether ΔNp63 is involved in the radioresistance of HNSCC cells. Cell survival was measured by a colony formation assay. Apoptosis was assessed by annexin V staining and cleaved caspase-3 expression. The results indicate that ΔNp63 knockdown decreased the survival of irradiated HNSCC cells, increased radiation-induced annexin V+ cells, and cleaved caspase-3 expression. These results show that ΔNp63 is involved in the radioresistance of HNSCC cells. We further investigated which specific karyopherin-α (KPNA) molecules, partners of KPNB1 for nuclear transport, are involved in nuclear ΔNp63 expression. The analysis of nuclear ΔNp63 protein expression suggests that KPNA1 is involved in nuclear ΔNp63 expression. Taken together, our results suggest that ΔNp63 is a KPNB1-carrying nucleoprotein that regulates radioresistance in HNSCC.

Glaucomatous optic neuropathy: Mitochondrial dynamics, dysfunction and protection in retinal ganglion cells

Glaucoma is a leading cause of irreversible blindness worldwide and is characterized by a slow, progressive, and multifactorial degeneration of retinal ganglion cells (RGCs) and their axons, resulting in vision loss. Despite its high prevalence in individuals 60 years of age and older, the causing factors contributing to glaucoma progression are currently not well characterized. Intraocular pressure (IOP) is the only proven treatable risk factor. However, lowering IOP is insufficient for preventing disease progression. One of the significant interests in glaucoma pathogenesis is understanding the structural and functional impairment of mitochondria in RGCs and their axons and synapses. Glaucomatous risk factors such as IOP elevation, aging, genetic variation, neuroinflammation, neurotrophic factor deprivation, and vascular dysregulation, are potential inducers for mitochondrial dysfunction in glaucoma. Because oxidative phosphorylation stress-mediated mitochondrial dysfunction is associated with structural and functional impairment of mitochondria in glaucomatous RGCs, understanding the underlying mechanisms and relationship between structural and functional alterations in mitochondria would be beneficial to developing mitochondria-related neuroprotection in RGCs and their axons and synapses against glaucomatous neurodegeneration. Here, we review the current studies focusing on mitochondrial dynamics-based structural and functional alterations in the mitochondria of glaucomatous RGCs and therapeutic strategies to protect RGCs against glaucomatous neurodegeneration.

The effects of non-functionalized polystyrene nanoparticles of different diameters on the induction of apoptosis and mTOR level in human peripheral blood mononuclear cells

Particles of various types of plastics, including polystyrene nanoparticles (PS-NPs), have been determined in human blood, placenta, and lungs. These findings suggest a potential detrimental effect of PS-NPs on bloodstream cells. The purpose of this study was to assess the mechanism underlying PS-NPs-induced apoptosis in human peripheral blood mononuclear cells (PBMCs). Non-functionalized PS-NPs of three diameters: 29 nm, 44 nm, and 72 nm were studied used in this research. PBMCs were isolated from human leukocyte-platelet buffy coat and treated with PS-NPs at concentrations ranging from 0.001 to 200 μg/mL for 24 h. Apoptotic mechanism of action was evaluated by determining the level of cytosolic calcium ions, as well as mitochondrial transmembrane potential, and ATP levels. Furthermore, detection of caspase-8, -9, and -3 activation, as well as mTOR level was conducted. The presence of apoptotic PBMCs was confirmed by the method of double staining of the cells with propidium iodide and FITC-conjugated Annexin V. We found that all tested NPs increased calcium ion and depleted mitochondrial transmembrane potential levels. The tested NPs also activated caspase-9 and caspase-3, and the smallest NPs of 29 nm of diameter also activated caspase-8. The results clearly showed that apoptotic changes and an increase of mTOR level depended on the size of the tested NPs, while the smallest particles caused the greatest alterations. PS-NPs of 26 nm of diameter activated the extrinsic pathway (increased caspase-8 activity), as well as intrinsic (mitochondrial) pathway (increased caspase-9 activity, raised calcium ion level, and decreased transmembrane mitochondrial potential) of apoptosis. All PS-NPs increased mTOR level at the concentrations smaller than those that induced apoptosis and its level returned to control value when the process of apoptosis escalated.

ANP32B promotes lung cancer progression by regulating VDAC1

It has been reported before that acidic leucine-rich nuclear phosphoprotein 32 family member B (ANP32B) plays roles in many cancers, yet no report of its role in lung cancer exists. In this study, we documented an elevation of ANP32B within lung cancer tissues and cells. Knockdown of ANP32B hindered the proliferation as well as migration of lung cancer cells, whereas overexpression of ANP32B helps to promote the malignant progression of lung cancer. ANP32B also regulates lung cancer cells' apoptosis and cell cycling. In addition, voltage-dependent anion channel 1 (VDAC1) has been found to be a downstream targeted gene of ANP32B and is positively regulated by ANP32B in lung cancer cells. According to our research, the expression of VDAC1 was positively associated with ANP32B expression in lung adenocarcinoma (r = 0.61, P < 0.001) samples by Pearson's correlation coefficient analysis. Furthermore, rescue experiments demonstrated that VDAC1 could rescue the effect of ANP32B expression on lung cancer cell proliferation and migration. Our results suggest that ANP32B overexpression facilitates lung cancer progression by increasing the expression of VDAC1. As such, we have revealed a novel mechanism regulating the connection between ANP32B and VDAC1 and a potential role of ANP32B as an oncogene and a clinical therapeutic target in lung cancer.

Apparent "mild depolarization of the inner mitochondrial membrane" as a result of a possible generation of the outer membrane potential

Recently reported kinase-linked mild depolarization of mitochondria, which prevents the generation of the reactive oxygen species (ROS) and disappears in various organs of the old mice, has been assumed to represent a crucial component of the mitochondrial anti-aging program. To measure mitochondrial inner membrane potential (IMP), the authors used fluorescent probe safranin O⁺. It is widely accepted that the accumulation of such cationic probes in the mitochondrial matrix depends exclusively on IMP, thus completely ignoring the possibility of the outer membrane potential (OMP) generation. However, computational analysis performed in the presented work suggests that the kinase-linked generation of the positive OMP might take place under the described conditions, because the measured potential includes the algebraic sum of both IMP and OMP. Alternatively to the suggested mild depolarization of mitochondria, the reported experimental data might reflect mainly a change of the positive OMP generated by the VDAC-kinase complexes. We also demonstrate that the reported in the literature mitochondrial hyperpolarization induced by erastin (known to prevent VDAC-tubulin interactions) and the depolarization caused by the mitochondrial VDAC knockdowns in the cancer cells might actually represent a decrease or increase, respectively, of the magnitude of the kinase-linked positive OMP. This is consistent with our hypothesis that VDAC voltage gating by the kinase-linked metabolically-dependent OMP plays a very important physiological role in regulating the cell energy metabolism under normal and pathological conditions, in the maintenance of the cell death resistance and even in the genetic aging program.

Modulation of Ca2+ signaling by antiapoptotic Bcl-2 versus Bcl-xL: From molecular mechanisms to relevance for cancer cell survival

Members of the Bcl-2-protein family are key controllers of apoptotic cell death. The family is divided into antiapoptotic (including Bcl-2 itself, Bcl-xL, Mcl-1, etc.) and proapoptotic members (Bax, Bak, Bim, Bim, Puma, Noxa, Bad, etc.). These proteins are well known for their canonical role in the mitochondria, where they control mitochondrial outer membrane permeabilization and subsequent apoptosis. However, several proteins are recognized as modulators of intracellular Ca²⁺ signals that originate from the endoplasmic reticulum (ER), the major intracellular Ca²⁺-storage organelle. More than 25 years ago, Bcl-2, the founding member of the family, was reported to control apoptosis through Ca²⁺ signaling. Further work elucidated that Bcl-2 directly targets and inhibits inositol 1,4,5-trisphosphate receptors (IP₃Rs), thereby suppressing proapoptotic Ca²⁺ signaling. In addition to Bcl-2, Bcl-xL was also shown to impact cell survival by sensitizing IP₃R function, thereby promoting prosurvival oscillatory Ca²⁺ release. However, new work challenges this model and demonstrates that Bcl-2 and Bcl-xL can both function as inhibitors of IP₃Rs. This suggests that, depending on the cell context, Bcl-xL could support very distinct Ca²⁺ patterns. This not only raises several questions but also opens new possibilities for the treatment of Bcl-xL-dependent cancers. In this review, we will discuss the similarities and divergences between Bcl-2 and Bcl-xL regarding Ca²⁺ homeostasis and IP₃R modulation from both a molecular and a functional point of view, with particular emphasis on cancer cell death resistance mechanisms.

MYC sensitises cells to apoptosis by driving energetic demand

The MYC oncogene is a potent driver of growth and proliferation but also sensitises cells to apoptosis, which limits its oncogenic potential. MYC induces several biosynthetic programmes and primary cells overexpressing MYC are highly sensitive to glutamine withdrawal suggesting that MYC-induced sensitisation to apoptosis may be due to imbalance of metabolic/energetic supply and demand. Here we show that MYC elevates global transcription and translation, even in the absence of glutamine, revealing metabolic demand without corresponding supply. Glutamine withdrawal from MRC-5 fibroblasts depletes key tricarboxylic acid (TCA) cycle metabolites and, in combination with MYC activation, leads to AMP accumulation and nucleotide catabolism indicative of energetic stress. Further analyses reveal that glutamine supports viability through TCA cycle energetics rather than asparagine biosynthesis and that TCA cycle inhibition confers tumour suppression on MYC-driven lymphoma in vivo. In summary, glutamine supports the viability of MYC-overexpressing cells through an energetic rather than a biosynthetic mechanism.

Notch1 Modulation of Cellular Calcium Regulates Mitochondrial Metabolism and Anti-Apoptotic Activity in T-Regulatory Cells

As the major hub of metabolic activity and an organelle sequestering pro-apoptogenic intermediates, mitochondria lie at the crossroads of cellular decisions of death and survival. Intracellular calcium is a key regulator of these outcomes with rapid, uncontrolled uptake into mitochondria, activating pro-apoptotic cascades that trigger cell death. Here, we show that calcium uptake and mitochondrial metabolism in murine T-regulatory cells (Tregs) is tuned by Notch1 activity. Based on analysis of Tregs and the HEK cell line, we present evidence that modulation of cellular calcium dynamics underpins Notch1 regulation of mitochondrial homeostasis and consequently anti-apoptotic activity. Targeted siRNA-mediated ablations reveal dependency on molecules controlling calcium release from the endoplasmic reticulum (ER) and the chaperone, glucose-regulated protein 75 (Grp75), the associated protein Voltage Dependent Anion Channel (VDAC)1 and the Mitochondrial Calcium Uniporter (MCU), which together facilitate ER calcium transfer and uptake into the mitochondria. Endogenous Notch1 is detected in immune-complexes with Grp75 and VDAC1. Deficits in mitochondrial oxidative and survival in Notch1 deficient Tregs, were corrected by the expression of recombinant Notch1 intracellular domain, and in part by recombinant Grp75. Thus, the modulation of calcium dynamics and consequently mitochondrial metabolism underlies Treg survival in conditions of nutrient stress. This work positions a key role for Notch1 activity in these outcomes.

Nephroprotective potential of Panduratin A against colistin-induced renal injury via attenuating mitochondrial dysfunction and cell apoptosis

Colistin is a last-resort polypeptide antibiotic widely used to treat against multidrug-resistant Gram-negative bacterial infections. However, this treatment is associated with nephrotoxicity. The aim of this study was to examine the potential protective effect of panduratin A, a bioactive compound of Boesenbergia rotunda, on colistin-induced nephrotoxicity in both in vivo and in vitro models. Intraperitoneal injection of 15 mg/kg colistin for 7 days markedly promoted renal tubular degeneration, increased blood urea nitrogen (BUN) levels, and upregulated the expression of renal injury biomarker and apoptosis proteins. In addition, treatment with colistin increased oxidative stress and apoptosis in mice kidney tissues. Interestingly, these defects were attenuated when co-administered of colistin with panduratin A (2.5 or 25 mg/kg). The underlying mechanisms of panduratin A attenuating colistin toxicity was investigated in human renal proximal tubular cells (RPTEC/TERT1). The mechanisms by which colistin-triggered cytotoxicity was determined by analysis of cell death, reactive oxygen species (ROS) levels, mitochondria function as well as the expression of proteins related to apoptosis pathway. Colistin treatment (200 µg/ml) significantly increased cell apoptosis, elevated ROS production, reduced mitochondrial membrane potential, and decreased anti-apoptotic protein (Bcl-2) expression. These effects were notably suppressed by co-treatment with panduratin A (5 μM). Collectively, panduratin A exerts as a novel nephroprotective agent to protect against colistin-induced renal injury by attenuating mitochondrial damage and renal cell apoptosis.

Exposure to benzo(a)pyrene suppresses mitophagy via ANT1-PINK1-Parkin pathway in ovarian corpus luteum during early pregnancy

Exposure to benzo (a)pyrene (BaP) has been confirmed to interfere with embryo implantation. As the primary organ of progesterone synthesis during early pregnancy, the ovarian corpus luteum (CL) is essential for embryo implantation and pregnancy maintenance. We previously demonstrated that BaP impaired luteal function, but the molecular mechanism remains unclear. In CL cells, mitochondria are the main sites of progesterone synthesis. Mitophagy, a particular type of autophagy, regulates mitochondrial quality by degrading damaged mitochondria and ensuring the homeostasis of cell physiology. Therefore, the present study investigated the effects and the potential molecular mechanisms of BaP on ovarian mitophagy during early pregnancy. We found that BaP and its metabolite, BPDE, inhibited autophagy and PINK1/Parkin-mediated mitophagy in the pregnant ovaries and luteinized granulosa cell, KGN. Notably, adenine nucleotide translocator 1 (ANT1), a crucial mediator of PINK1-dependent mitophagy, was suppressed by BaP and BPDE both in vivo and in vitro. The inhibition of ANT1 leads to the decrease in the PINK1 bound to the outer membrane of mitochondria and consequently reduces recruitment of Parkin to the mitochondria, which is required for the subsequent clearance of mitochondria. Meanwhile, exposure to BPDE also damaged mitochondrial function, causing the reduction in mitochondrial potential and ATP production. Overexpression of ANT1 in KGN cells partially relieved the inhibition of mitophagy caused by BPDE, restored mitochondrial function and expression of hormone synthesis-associated genes. Collectively, our study firstly clarified that BaP and BPDE suppress mitophagy of CL cells via the ANT1-PINK1-Parkin pathway, which provides a new insight to explore the detailed mechanism of the BaP-induced ovarian toxicity.

Whole and Purified Aqueous Extracts of Nigella sativa L. Seeds Attenuate Apoptosis and the Overproduction of Reactive Oxygen Species Triggered by p53 Over-Expression in the Yeast Saccharomyces cerevisiae

Plants are an important source of pharmacologically active compounds. In the present work, we characterize the impact of black cumin (Nigella sativa L.) aqueous extracts on a yeast model of p53-dependent apoptosis. To this end, the Saccharomyces cerevisiae recombinant strain over-expressing p53 was used. The over-expression of p53 triggers the expression of apoptotic markers: the externalization of phosphatidylserine, mitochondrial defect associated with cytochrome-c release and the induction of DNA strand breaks. These different effects were attenuated by Nigella sativa L. aqueous extracts, whereas these extracts have no effect on the level of p53 expression. Thus, we focus on the anti-apoptotic molecules present in the aqueous extract of Nigella sativa L. These extracts were purified and characterized by complementary chromatographic methods. Specific fluorescent probes were used to determine the effect of the extracts on yeast apoptosis. Yeast cells over-expressing p53 decrease in relative size and have lower mitochondrial content. The decrease in cell size was proportional to the decrease in mitochondrial content and of mitochondrial membrane potential (ΔΨm). These effects were prevented by the purified aqueous fraction obtained by fractionation with different columns, named C4 fraction. Yeast cell death was also characterized by reactive oxygen species (ROS) overproduction. In the presence of the C4 fraction, ROS overproduction was strongly reduced. We also noted that the C4 fraction promotes the cell growth of control yeast cells, which do not express p53, supporting the fact that this purified extract acts on cellular mediators activating cell proliferation independently of p53. Altogether, our data obtained on yeast cells over-expressing p53 demonstrate that anti-apoptotic molecules targeting p53-induced apoptosis associated with mitochondrial dysfunction and ROS overproduction are present in the aqueous extracts of Nigella seeds and in the purified aqueous C4 fraction.

Activation of RAS/MAPK pathway confers MCL-1 mediated acquired resistance to BCL-2 inhibitor venetoclax in acute myeloid leukemia

Despite high initial response rates, acute myeloid leukemia (AML) treated with the BCL-2-selective inhibitor venetoclax (VEN) alone or in combinations commonly acquires resistance. We performed gene/protein expression, metabolomic and methylation analyses of isogenic AML cell lines sensitive or resistant to VEN, and identified the activation of RAS/MAPK pathway, leading to increased stability and higher levels of MCL-1 protein, as a major acquired mechanism of VEN resistance. MCL-1 sustained survival and maintained mitochondrial respiration in VEN-RE cells, which had impaired electron transport chain (ETC) complex II activity, and MCL-1 silencing or pharmacologic inhibition restored VEN sensitivity. In support of the importance of RAS/MAPK activation, we found by single-cell DNA sequencing rapid clonal selection of RAS-mutated clones in AML patients treated with VEN-containing regimens. In summary, these findings establish RAS/MAPK/MCL-1 and mitochondrial fitness as key survival mechanisms of VEN-RE AML and provide the rationale for combinatorial strategies effectively targeting these pathways.

A Note of Caution: Gramicidin Affects Signaling Pathways Independently of Its Effects on Plasma Membrane Conductance

Gramicidin is a thoroughly studied cation ionophore widely used to experimentally manipulate the plasma membrane potential (PMP). In addition, it has been established that the drug, due to its hydrophobic nature, is capable of affecting the organization of membrane lipids. We have previously shown that modifications in the plasma membrane potential of epithelial cells in culture determine reorganizations of the cytoskeleton. To elucidate the molecular mechanisms involved, we explored the effects of PMP depolarization on some putative signaling intermediates. In the course of these studies, we came across some results that could not be interpreted in terms of the properties of gramicidin as an ionic channel. The purpose of the present work is to communicate these results and, in general, to draw attention to the fact that gramicidin effects can be misleadingly attributed to its ionic or electrical properties. In addition, this work also contributes with some novel findings of the modifications provoked on the signaling intermediates by PMP depolarization and hyperpolarization.

Monitoring Mitochondrial Function in Aedes albopictus C6/36 Cell Line during Dengue Virus Infection

Simple Summary

Dengue is an important and growing public health problem. To date, no specific therapeutic or effective prophylactic measures exist. Therefore, vector control remains the primary approach to prevent dengue virus (DENV) infection in humans. Recent findings highlight that viruses regulate mitochondrial function and dynamics to facilitate viral proliferation. In this study, we report that DENV infection modulates mitochondrial physiology in C6/36 mosquito cells. Our results revealed that DENV alters redox metabolism and mitochondrial membrane potential without any significant change in cellular ATP pool or viability. In addition, we observed preservation of the respiratory control ratio and translocation of mitofusins to mitochondria. These results suggest that mitochondrial fusion could be required for the maintenance of mitochondrial function in C6/36 mosquito cells infected with DENV.

Abstract

Aedes aegypti and Aedes albopictus mosquitoes are responsible for dengue virus (DENV) transmission in tropical and subtropical areas worldwide, where an estimated 3 billion people live at risk of DENV exposure. DENV-infected individuals show symptoms ranging from sub-clinical or mild to hemorrhagic fever. Infected mosquitoes do not show detectable signs of disease, even though the virus maintains a lifelong persistent infection. The interactions between viruses and host mitochondria are crucial for virus replication and pathogenicity. DENV infection in vertebrate cells modulates mitochondrial function and dynamics to facilitate viral proliferation. Here, we describe that DENV also regulates mitochondrial function and morphology in infected C6/36 mosquito cells (derived from Aedes albopictus). Our results showed that DENV infection increased ROS (reactive oxygen species) production, modulated mitochondrial transmembrane potential and induced changes in mitochondrial respiration. Furthermore, we offer the first evidence that DENV causes translocation of mitofusins to mitochondria in the C6/36 mosquito cell line. Another protein Drp-1 (Dynamin-related protein 1) did not localize to mitochondria in DENV-infected cells. This observation therefore ruled out the possibility that the abovementioned alterations in mitochondrial function are associated with mitochondrial fission. In summary, this report provides some key insights into the virus–mitochondria crosstalk in DENV infected mosquito cells.

Perfluorodecanoic acid induces meiotic defects and deterioration of mice oocytes in vitro

Perfluorodecanoic acid (PFDA) is a member of the perfluoroalkyl substances, which are toxic to organic functions. Recently, it has been found in follicular fluid, seriously interfering with reproduction. Follicular fluid provides the oocyte with necessary resources during the process of oocytes maturation. However, the effects of PFDA on the oocyte need investigation. Our study evaluated the impacts of PFDA on the meiosis and development potential of mouse oocytes by exposing oocytes to PFDA in vitro at 350, 400, and 450 μM concentrations. The results showed that exposure to PFDA resulted in the first meiotic prophase arrest by obstructing the function of the maturation-promoting factor. It also induced the dysfunction of the spindle assembly checkpoint, expedited the progression of the first meiotic process, and increased the risk of aneuploidy. The oocytes treated with PFDA had a broken cytoskeleton which also contributed to meiotic maturation failure. Besides, PFDA exposure caused mitochondria defections, increased the reactive oxygen species level in oocytes, and consequently induced oocyte apoptosis. Moreover, PFDA produced epigenetic modifications in oocytes and increased the frequency of mature oocytes with declined development potential. In summary, our data indicated that PFDA disturbs the meiotic process and induces oocyte quality deterioration.

Bioenergetic and inflammatory systemic phenotypes in Alzheimer's disease APOE ε4-carriers

We examined the impact of an APOE ε4 genotype on Alzheimer's disease (AD) subject platelet and lymphocyte metabolism. Mean platelet mitochondrial cytochrome oxidase Vmax activity was lower in APOE ε4 carriers and lymphocyte Annexin V, a marker of apoptosis, was significantly higher. Proteins that mediate mitophagy and energy sensing were higher in APOE ε4 lymphocytes which could represent compensatory changes and recapitulate phenomena observed in post‐mortem AD brains. Analysis of the lipid synthesis pathway found higher AceCSI, ATP CL, and phosphorylated ACC levels in APOE ε4 lymphocytes. Lymphocyte ACC changes were also observed in post‐mortem brain tissue. Lymphocyte RNAseq showed lower APOE ε4 carrier sphingolipid Transporter 3 (SPNS3) and integrin Subunit Alpha 1 (ITGA1) expression. RNAseq pathway analysis revealed APOE ε4 alleles activated inflammatory pathways and modulated bioenergetic signaling. These findings support a relationship between APOE genotype and bioenergetic pathways and indicate platelets and lymphocytes from APOE ε4 carriers exist in a state of bioenergetic stress. Neither medication use nor brain‐localized AD histopathology can account for these findings, which define an APOE ε4‐determined molecular and systemic phenotype that informs AD etiology.

Bcl-2 Family of Proteins in the Control of Mitochondrial Calcium Signalling: An Old Chap with New Roles

Bcl-2 family proteins are considered as one of the major regulators of apoptosis. Indeed, this family is known to control the mitochondrial outer membrane permeabilization (MOMP): a central step in the mitochondrial pathway of apoptosis. However, in recent years Bcl-2 family members began to emerge as a new class of intracellular calcium (Ca²⁺) regulators. At mitochondria-ER contacts (MERCs) these proteins are able to interact with major Ca²⁺ transporters, thus controlling mitochondrial Ca²⁺ homeostasis and downstream Ca²⁺ signalling pathways. Beyond the regulation of cell survival, this Bcl-2-dependent control over the mitochondrial Ca²⁺ dynamics has far-reaching consequences on the physiology of the cell. Here, we review how the Bcl-2 family of proteins mechanistically regulate mitochondrial Ca²⁺ homeostasis and how this regulation orchestrates cell death/survival decisions as well as the non-apoptotic process of cell migration.

Therapeutic Potential of Pharmacological Targeting NLRP3 Inflammasome Complex in Cancer

Introduction

Dysregulation of NLRP3 inflammasome complex formation can promote chronic inflammation by increased release of IL-1β. However, the effect of NLRP3 complex formation on tumor progression remains controversial. Therefore, we sought to determine the effect of NLRP3 modulation on the growth of the different types of cancer cells, derived from lung, breast, and prostate cancers as well as neuroblastoma and glioblastoma in-vitro.

Method

The effect of Caspase 1 inhibitor (VX765) and combination of LPS/Nigericin on NLRP3 inflammasome activity was analyzed in A549 (lung cancer), MCF-7 (breast cancer), PC3 (prostate cancer), SH-SY5Y (neuroblastoma), and U138MG (glioblastoma) cells. Human fibroblasts were used as control cells. The effect of VX765 and LPS/Nigericin on NLRP3 expression was analyzed using western blot, while IL-1β and IL-18 secretion was detected by ELISA. Tumor cell viability and progression were determined using Annexin V, cell proliferation assay, LDH assay, sphere formation assay, transmission electron microscopy, and a multiplex cytokine assay. Also, angiogenesis was investigated by a tube formation assay. VEGF and MMPs secretion were detected by ELISA and a multiplex assay, respectively. Statistical analysis was done using one-way ANOVA with Tukey’s analyses and Kruskal–Wallis one-way analysis of variance.

Results

LPS/Nigericin increased NRLP3 protein expression as well as IL-1β and IL-18 secretion in PC3 and U138MG cells compared to A549, MCF7, SH-SY5Y cells, and fibroblasts. In contrast, MIF expression was commonly found upregulated in A549, PC3, SH-SY5Y, and U138MG cells and fibroblasts after Nigericin treatment. Nigericin and a combination of LPS/Nigericin decreased the cell viability and proliferation. Also, LPS/Nigericin significantly increased tumorsphere size in PC3 and U138MG cells. In contrast, the sphere size was reduced in MCF7 and SH-SY5Y cells treated with LPS/Nigericin, while no effect was detected in A549 cells. VX765 increased secretion of CCL24 in A549, MCF7, PC3, and fibroblasts as well as CCL11 and CCL26 in SH-SY5Y cells. Also, VX765 significantly increased the production of VEGF and MMPs and stimulated angiogenesis in all tumor cell lines.

Discussion

Our data suggest that NLRP3 activation using Nigericin could be a novel therapeutic approach to control the growth of tumors producing a low level of IL-1β and IL-18.

Altered VDAC-HK association and apoptosis in mouse peripheral blood lymphocytes exposed to diabetic condition: an in vitro and in vivo study

Increased apoptotic lymphocytes have been correlated to a high incidence of infection in poorly controlled diabetes. This study aimed to determine whether altered voltage-dependent anion channel (VDAC)-hexokinase (HK) association contributes to the increase in apoptosis. Mouse peripheral blood lymphocytes (PBL) exposed to high glucose (Glc)/palmitic acid (PA) were used as the in vitro model, which was compared with PBL isolated from alloxan-induced diabetic mice (in vivo model). Our results showed a significant increase in apoptosis as indicated by the apoptotic index, caspase-3 activity, mitochondrial membrane potential and ultrastructural study. HK and glucose-6-phosphate dehydrogenase (G6PDH) activities were markedly reduced with a profound increase in glucose-6-phosphate level. Co-immunoprecipitation confirms HK interaction with VDAC, an outer mitochondrial membrane protein. Inhibited glycolytic enzyme, i.e. HK and reduced HK-VDAC interaction in our study could contribute to increased apoptosis in lymphocytes exposed to high Glc/PA. Targeting HK-VDAC interaction may therefore provide therapeutic potential for the treatment of diabetes-associated infection.

Increased demand for NAD+ relative to ATP drives aerobic glycolysis

Aerobic glycolysis, or preferential fermentation of glucose-derived pyruvate to lactate despite available oxygen, is associated with proliferation across many organisms and conditions. To better understand that association, we examined the metabolic consequence of activating the pyruvate dehydrogenase complex (PDH) to increase pyruvate oxidation at the expense of fermentation. We find that increasing PDH activity impairs cell proliferation by reducing the NAD⁺/NADH ratio. This change in NAD⁺/NADH is caused by increased mitochondrial membrane potential that impairs mitochondrial electron transport and NAD⁺ regeneration. Uncoupling respiration from ATP synthesis or increasing ATP hydrolysis restores NAD⁺/NADH homeostasis and proliferation even when glucose oxidation is increased. These data suggest that when demand for NAD⁺ to support oxidation reactions exceeds the rate of ATP turnover in cells, NAD⁺ regeneration by mitochondrial respiration becomes constrained, promoting fermentation, despite available oxygen. This argues that cells engage in aerobic glycolysis when the demand for NAD⁺ is in excess of the demand for ATP.

Evidences of a Direct Relationship between Cellular Fuel Supply and Ciliogenesis Regulated by Hypoxic VDAC1-ΔC

Metabolic flexibility is the ability of a cell to adapt its metabolism to changes in its surrounding environment. Such adaptability, combined with apoptosis resistance provides cancer cells with a survival advantage. Mitochondrial voltage-dependent anion channel 1 (VDAC1) has been defined as a metabolic checkpoint at the crossroad of these two processes. Here, we show that the hypoxia-induced cleaved form of VDAC1 (VDAC1-ΔC) is implicated in both the up-regulation of glycolysis and the mitochondrial respiration. We demonstrate that VDAC1-ΔC, due to the loss of the putative phosphorylation site at serine 215, concomitantly with the loss of interaction with tubulin and microtubules, reprograms the cell to utilize more metabolites, favoring cell growth in hypoxic microenvironment. We further found that VDAC1-ΔC represses ciliogenesis and thus participates in ciliopathy, a group of genetic disorders involving dysfunctional primary cilium. Cancer, although not representing a ciliopathy, is tightly linked to cilia. Moreover, we highlight, for the first time, a direct relationship between the cilium and cancer cell metabolism. Our study provides the first new comprehensive molecular-level model centered on VDAC1-ΔC integrating metabolic flexibility, ciliogenesis, and enhanced survival in a hypoxic microenvironment.

Regulation of Cell Death by Mitochondrial Transport Systems of Calcium and Bcl-2 Proteins

Mitochondria represent the fundamental system for cellular energy metabolism, by not only supplying energy in the form of ATP, but also by affecting physiology and cell death via the regulation of calcium homeostasis and the activity of Bcl-2 proteins. A lot of research has recently been devoted to understanding the interplay between Bcl-2 proteins, the regulation of these interactions within the cell, and how these interactions lead to the changes in calcium homeostasis. However, the role of Bcl-2 proteins in the mediation of mitochondrial calcium homeostasis, and therefore the induction of cell death pathways, remain underestimated and are still not well understood. In this review, we first summarize our knowledge about calcium transport systems in mitochondria, which, when miss-regulated, can induce necrosis. We continue by reviewing and analyzing the functions of Bcl-2 proteins in apoptosis. Finally, we link these two regulatory mechanisms together, exploring the interactions between the mitochondrial Ca2+ transport systems and Bcl-2 proteins, both capable of inducing cell death, with the potential to determine the cell death pathway-either the apoptotic or the necrotic one.

Physiopathology of the Permeability Transition Pore: Molecular Mechanisms in Human Pathology

Mitochondrial permeability transition (MPT) is the sudden loss in the permeability of the inner mitochondrial membrane (IMM) to low-molecular-weight solutes. Due to osmotic forces, MPT is paralleled by a massive influx of water into the mitochondrial matrix, eventually leading to the structural collapse of the organelle. Thus, MPT can initiate outer-mitochondrial-membrane permeabilization (MOMP), promoting the activation of the apoptotic caspase cascade and caspase-independent cell-death mechanisms. The induction of MPT is mostly dependent on mitochondrial reactive oxygen species (ROS) and Ca²⁺, but is also dependent on the metabolic stage of the affected cell and signaling events. Therefore, since its discovery in the late 1970s, the role of MPT in human pathology has been heavily investigated. Here, we summarize the most significant findings corroborating a role for MPT in the etiology of a spectrum of human diseases, including diseases characterized by acute or chronic loss of adult cells and those characterized by neoplastic initiation.

Double agents of cell death: novel emerging functions of apoptotic regulators

Apoptosis is a highly regulated form of cell death that is required for many homeostatic and pathological processes. Recently, alternative cell death pathways have emerged whose regulation is dependent on proteins with canonical functions in apoptosis. Dysregulation of apoptotic signaling frequently underlies the pathogenesis of many cancers, reinforcing the need to develop therapies that initiate alternative cell death processes. This review outlines the convergence points between apoptosis and other death pathways with the purpose of identifying novel strategies for the treatment of apoptosis-refractory cancers. Apoptosis proteins can play key roles in the initiation, regulation, and execution of nonapoptotic death processes that include necroptosis, autophagy, pyroptosis, mPTP-mediated necrosis, and ferroptosis. Notably, recent evidence illustrates that dying cells can exhibit biochemical and molecular characteristics of more than one different type of regulated cell death. Thus, this review highlights the amazing complexity and interconnectivity of cell death processes and also raises the idea that a top-to-bottom approach to describing cell death mechanisms may be inadequate for fully understanding the means by which cells die.

The apoptosis inhibitor Bcl-xL controls breast cancer cell migration through mitochondria-dependent reactive oxygen species production

The Bcl-xL apoptosis inhibitor plays a major role in vertebrate development. In addition to its effect on apoptosis, Bcl-xL is also involved in cell migration and mitochondrial metabolism. These effects may favour the onset and dissemination of metastasis. However, the underlying molecular mechanisms remain to be fully understood. Here we focus on the control of cell migration by Bcl-xL in the context of breast cancer cells. We show that Bcl-xL silencing led to migration defects in Hs578T and MDA-MB231 cells. These defects were rescued by re-expressing mitochondria-addressed, but not endoplasmic reticulum-addressed, Bcl-xL. The use of BH3 mimetics, such as ABT-737 and WEHI-539 confirmed that the effect of Bcl-xL on migration did not depend on interactions with BH3-containing death accelerators such as Bax or BH3-only proteins. In contrast, the use of a BH4 peptide that disrupts the Bcl-xL/VDAC1 complex supports that Bcl-xL by acting on VDAC1 permeability contributes to cell migration through the promotion of reactive oxygen species production by the electron transport chain. Collectively our data highlight the key role of Bcl-xL at the interface between cell metabolism, cell death, and cell migration, thus exposing the VDAC1/Bcl-xL interaction as a promising target for anti-tumour therapy in the context of metastatic breast cancer.

Neurotoxicity and apoptosis induced by pyrroloquinoline quinone and its ester derivative on primary cortical neurons

Pyrroloquinoline quinone (PQQ) and its esterified derivative, PQQ ester (PQQE), have potential to treat or diagnose neurological and psychological disorders. However, their neurotoxicity remains unclear. To provide reference data for the brain targeting drug delivery techniques, the cytotoxic effects of PQQ and PQQE were examined in primary mouse cortical neurons. The results indicated that both PQQ and PQQE decreased neuron viability, reduced intracellular ATP level and disrupted the mitochondrial membrane potential in a concentration- and time-dependent manner, while PQQ was less potent than PQQE. PQQ and PQQE induced apoptosis involving increase of Bax, decrease of Bcl-2, release of mitochondrial cytochrome C into the cytosol, activation of caspase-3 and cleavage of PARP. A single mouse intracephalic injection of PQQ or PQQE showed similar results. Based on these findings, high-concentration PQQ or PQQE treatment could induce a wide range of neurotoxicity and apoptosis. The lowest observed adverse effect levels (LOAELs) of PQQ and PQQE were 10 μM and 2 μM respectively and the no observed adverse effect levels (NOAELs) were 5 μM and 1 μM respectively in mice cortical neurons.

Identification of a new aggressive axis driven by ciliogenesis and absence of VDAC1-ΔC in clear cell Renal Cell Carcinoma patients

Rationale: Renal cell carcinoma (RCC) accounts for about 2% of all adult cancers, and clear cell RCC (ccRCC) is the most common RCC histologic subtype. A hallmark of ccRCC is the loss of the primary cilium, a cellular antenna that senses a wide variety of signals. Loss of this key organelle in ccRCC is associated with the loss of the von Hippel-Lindau protein (VHL). However, not all mechanisms of ciliopathy have been clearly elucidated. Methods: By using RCC4 renal cancer cells and patient samples, we examined the regulation of ciliogenesis via the presence or absence of the hypoxic form of the voltage-dependent anion channel (VDAC1-ΔC) and its impact on tumor aggressiveness. Three independent cohorts were analyzed. Cohort A was from PREDIR and included 12 patients with hereditary pVHL mutations and 22 sporadic patients presenting tumors with wild-type pVHL or mutated pVHL; Cohort B included tissue samples from 43 patients with non-metastatic ccRCC who had undergone surgery; and Cohort C was composed of 375 non-metastatic ccRCC tumor samples from The Cancer Genome Atlas (TCGA) and was used for validation. The presence of VDAC1-ΔC and legumain was determined by immunoblot. Transcriptional regulation of IFT20/GLI1 expression was evaluated by qPCR. Ciliogenesis was detected using both mouse anti-acetylated α-tubulin and rabbit polyclonal ARL13B antibodies for immunofluorescence. Results: Our study defines, for the first time, a group of ccRCC patients in which the hypoxia-cleaved form of VDAC1 (VDAC1-ΔC) induces resorption of the primary cilium in a Hypoxia-Inducible Factor-1 (HIF-1)-dependent manner. An additional novel group, in which the primary cilium is re-expressed or maintained, lacked VDAC1-ΔC yet maintained glycolysis, a signature of epithelial-mesenchymal transition (EMT) and more aggressive tumor progression, but was independent to VHL. Moreover, these patients were less sensitive to sunitinib, the first-line treatment for ccRCC, but were potentially suitable for immunotherapy, as indicated by the immunophenoscore and the presence of PDL1 expression. Conclusion: This study provides a new way to classify ccRCC patients and proposes potential therapeutic targets linked to metabolism and immunotherapy.

Role of the RAB7 Protein in Tumor Progression and Cisplatin Chemoresistance

RAB7 is a small guanosine triphosphatase (GTPase) extensively studied as regulator of vesicular trafficking. Indeed, its role is fundamental in several steps of the late endocytic pathway, including endosome maturation, transport from early endosomes to late endosomes and lysosomes, clustering and fusion of late endosomes and lysosomes in the perinuclear region and lysosomal biogenesis. Besides endocytosis, RAB7 is important for a number of other cellular processes among which, autophagy, apoptosis, signaling, and cell migration. Given the importance of RAB7 in these cellular processes, the interest to study the role of RAB7 in cancer progression is widely grown. Here, we describe the current understanding of oncogenic and oncosuppressor functions of RAB7 analyzing cellular context and other environmental factors in which it elicits pro and/or antitumorigenic effects. We also discuss the role of RAB7 in cisplatin resistance associated with its ability to regulate the late endosomal pathway, lysosomal biogenesis and extracellular vesicle secretion. Finally, we examined the potential cancer therapeutic strategies targeting the different molecular events in which RAB7 is involved.

Role of coenzymes in cancer metabolism

Cancer is a heterogeneous set of diseases characterized by the rewiring of cellular signaling and the reprogramming of metabolic pathways to sustain growth and proliferation. In past decades, studies were focused primarily on the genetic complexity of cancer. Recently, increasing number of studies have discovered several mutations among metabolic enzymes in different tumor cells. Most of the enzymes are regulated by coenzymes, organic cofactors, that function as intermediate carrier of electrons or functional groups that are transferred during the reaction. However, the precise role of cofactors is not well elucidated. In this review, we discuss several metabolic enzymes associated to cancer metabolism rewiring, whose inhibition may represent a therapeutic target. Such enzymes, upon expression or inhibition, may impact also the coenzymes levels, but only in few cases, it was possible to direct correlate coenzymes changes with a specific enzyme. In addition, we also summarize an up-to-date information on biological role of some coenzymes, preclinical and clinical studies, that have been carried out in various cancers and their outputs.

BCL2 and BCL(X)L selective inhibitors decrease mitochondrial ATP production in breast cancer cells and are synthetically lethal when combined with 2-deoxy-D-glucose

Cancer cells display differences regarding their engagement of glycolytic vs. mitochondrial oxidative phosphorylation (OXPHOS) pathway. Triple negative breast cancer, an aggressive form of breast cancer, is characterized by elevated glycolysis, while estrogen receptor positive breast cancer cells rely predominantly on OXPHOS. BCL2 proteins control the process of mitochondrial outer membrane permeabilization during apoptosis, but also regulate cellular bioenergetics. Because BCL2 proteins are overexpressed in breast cancer and targetable by selective antagonists, we here analysed the effect of BCL2 and BCL(X)L selective inhibitors, Venetoclax and WEHI-539, on mitochondrial bioenergetics and cell death. Employing single cell imaging using a FRET-based mitochondrial ATP sensor, we found that MCF7 breast cancer cells supplied with mitochondrial substrates reduced their mitochondrial ATP production when treated with Venetoclax or WEHI-539 at concentrations that per se did not induce cell death. Treatments with lower concentrations of both inhibitors also reduced the length of the mitochondrial network and the dynamics, as evaluated by quantitative confocal microscopy. We next tested the hypothesis that mitochondrial ATP production inhibition with BCL2 or BCL(X)L antagonists was synthetically lethal when combined with glycolysis inhibition. Treatment with 2-deoxy-D-glucose in combination with Venetoclax or WEHI-539 synergistically reduced the cellular bioenergetics of ER+ and TNBC breast cancer cells and abolished their clonogenic potential. Synthetic lethality was also observed when cultures were grown in 3D spheres. Our findings demonstrate that BCL2 antagonists exert potent effects on cancer metabolism independent of cell death-inducing effects, and demonstrate a synthetic lethality when these are applied in combination with glycolysis inhibitors.

VDAC1 as Pharmacological Target in Cancer and Neurodegeneration: Focus on Its Role in Apoptosis

Cancer and neurodegeneration are different classes of diseases that share the involvement of mitochondria in their pathogenesis. Whereas the high glycolytic rate (the so-called Warburg metabolism) and the suppression of apoptosis are key elements for the establishment and maintenance of cancer cells, mitochondrial dysfunction and increased cell death mark neurodegeneration. As a main actor in the regulation of cell metabolism and apoptosis, VDAC may represent the common point between these two broad families of pathologies. Located in the outer mitochondrial membrane, VDAC forms channels that control the flux of ions and metabolites across the mitochondrion thus mediating the organelle's cross-talk with the rest of the cell. Furthermore, the interaction with both pro-apoptotic and anti-apoptotic factors makes VDAC a gatekeeper for mitochondria-mediated cell death and survival signaling pathways. Unfortunately, the lack of an evident druggability of this protein, since it has no defined binding or active sites, makes the quest for VDAC interacting molecules a difficult tale. Pharmacologically active molecules of different classes have been proposed to hit cancer and neurodegeneration. In this work, we provide an exhaustive and detailed survey of all the molecules, peptides, and microRNAs that exploit VDAC in the treatment of the two examined classes of pathologies. The mechanism of action and the potential or effectiveness of each compound are discussed.

Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018

Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field.

Sodium citrate inhibits the proliferation of human gastric adenocarcinoma epithelia cells

The objective of the present study was to investigate the cytotoxic effects of sodium citrate on human gastric adenocarcinoma epithelia AGS cells. Numerous cytotoxicity-associated sodium citrate-induced effects were assessed, including cell viability and proliferation, cytokine expression and caspase activity. In vitro studies demonstrated that incubation with sodium citrate (>3.125 mM) inhibited AGS cell viability and proliferation in a dose-dependent manner. Incubation with sodium citrate for 24 h revealed that the levels of interleukin-1β (IL-1β), IL-8 and tumor necrosis factor increased with an increasing of dose of sodium citrate, whereas the IL-6 levels exhibited only a slight alteration. In addition, increases in caspase-3 and -9 activities were associated with increased duration of treatment and dosage of sodium citrate. Collectively, the results of the present study demonstrated that treatment with sodium citrate at higher concentrations or for longer durations exerts a cytotoxic effect on AGS cells via the induction of the intrinsic apoptosis pathway and the alteration in the levels of certain cytokines.

Decreased expression of microRNA-320a promotes proliferation and invasion of non-small cell lung cancer cells by increasing VDAC1 expression

Accumulating evidence indicates that Voltage Dependent Anion Channel 1 (VDAC1) correlates with the initiation and progression of non-small cell lung cancer (NSCLC). However, the regulatory mechanism of VDAC1 in NSCLC remains unclear. Previous studies have reported that expression of miR-320a was decreased in human primary squamous cell lung carcinoma, which prompted us to investigate whether there is a functional link between decreased miR-320a and a high expression of VDAC1. In the present report, using computational analysis, we first show that miR-320a has a potential binding site on VDAC1 mRNA, and expression of miR-320a was decreased in NSCLC cell lines. Using gain-of-function and rescue experiments, we demonstrate that VDAC1 is a direct target of miR-320a in NSCLC cells, and miR-320a inhibits VDAC1 expression in NSCLC cells. Further we show that MiR-320a was significantly decreased in NSCLC tissues compared with adjacent non-tumor tissues, and MiR-320a level is negatively correlated with VDAC1 in NSCLC tissues by Pearson's correlation coefficient analysis. Moreover, using cellular ATP assay, we found that suppression of VDAC1 expression may inhibit cell proliferation and invasion of NSCLC by decreasing cell energy and metabolism. Importantly, we showed that ectopic overexpression of miR-320a blocked tumor cell proliferation and invasion, both in vitro and in vivo, through inhibiting VDAC1. Our results suggest that reduced expression of miR-320a facilitates the development of NSCLCs by increasing VDAC1 expression. We identified a novel regulatory mechanism between miR-320a and VDAC1, and miR-320a may serve as a tumor suppressor gene and a promising therapeutic target of NSCLCs.

Carbon monoxide (CO) modulates hydrogen peroxide (H2O2)-mediated cellular dysfunction by targeting mitochondria in rabbit lens epithelial cells

Mitochondrial components are of great importance for the maintenance of lens transparency. In our previous work, we confirmed that carbon monoxide (CO) can protect human and rabbit lens epithelial cells (LECs) from hydrogen peroxide (H₂O₂)-mediated apoptosis, while the mechanism remains undefined. Because CO can bind to mitochondrial cytochrome c oxidase (COX), we evaluated the effect of CO on the regulation of mitochondrial biogenesis and function in H₂O₂-treated rabbit LECs. To evaluate mitochondrial biogenesis, several mitochondrial transcription factors (PGC-1α, NRF-1, and mtTFA) were detected by western blot analysis. To assess cellular metabolism, adenosine triphosphate (ATP) levels and COX enzymatic activity were measured. In addition, mitochondrial permeability transition pores (mPTP) opening, dissipation of mitochondrial membrane potential (ΔΨm), cytochrome c mitochondrial translocation, and apoptotic molecules were also detected to evaluate mitochondrial apoptosis pathway. Furthermore, the interaction of Bcl-2 and COX was assessed by co-immunoprecipitation. Finally, CO-mediated regulation of cellular function was detected in Bcl-2-knockdown cells. Our results confirmed that CO pretreatment restored H₂O₂-induced down-regulation of mitochondrial transcription factors expression, COX activity and ATP production. Moreover, CO pretreatment attenuated mPTP opening, ΔΨm loss, cytochrome c mitochondrial translocation, and activation of apoptotic molecules. Bcl-2 was identified to bind to COX, and silence of Bcl-2 expression prevented CO-regulated cellular metabolism and cytoprotection. These data suggest that CO modulates H₂O₂-induced cellular dysfunction by increasing mitochondrial biogenesis, enhancing cellular metabolism, and attenuating mitochondrial apoptosis cascade. Moreover, Bcl-2 expression was vital for CO to regulate cellular metabolism and cytoprotection in LECs.

Cytotoxicity of portoamides in human cancer cells and analysis of the molecular mechanisms of action

Portoamides are cyclic peptides produced and released by the cyanobacterial strain Phormidium sp. presumably to interfere with other organisms in their ecosystems ("allelopathy"). Portoamides were previously demonstrated to have an antiproliferative effect on human lung carcinoma cells, but the underlying mechanism of this activity has not been described. In the present work, the effects of portoamides on proliferation were examined in eight human cancer cell lines and two non-carcinogenic cell lines, and major differences in sensitivities were observed. To generate hypotheses with regard to molecular mechanisms of action, quantitative proteomics using 2D gel electrophoresis and MALDI-TOF/TOF were performed on the colon carcinoma cell line HT-29. The expression of proteins involved in energy metabolism (mitochondrial respiratory chain and pentose phosphate pathway) was found to be affected. The hypothesis of altered energy metabolism was tested in further experiments. Exposure to portoamides resulted in reduced cellular ATP content, likely due to decreased mitochondrial energy production. Mitochondrial hyperpolarization and reduced mitochondrial reductive capacity was observed in treated cells. Furthermore, alterations in the expression of peroxiredoxins (PRDX4, PRDX6) and components of proteasome subunits (PSB4, PSA6) were observed in portoamide-treated cells, but these alterations were not associated with detectable increases in oxidative stress. We conclude that the cytotoxic activity of portoamides is associated with disturbance of energy metabolism, and alterations in mitochondrial structure and function.

Melanoma Inhibition by Anthocyanins Is Associated with the Reduction of Oxidative Stress Biomarkers and Changes in Mitochondrial Membrane Potential

Anthocyanins are water soluble pigments which have been proved to exhibit health benefits. Several studies have investigated their effects on several types of cancer, but little attention has been given to melanoma. The phytochemical content of nine different berry samples was assessed by liquid chromatography followed by electrospray ionization mass spectrometry (LC-ESI⁺-MS). Twenty-six anthocyanins were identified, after a previous C₁₈ Sep-pak clean-up procedure. Chokeberry and red grape anthocyanins rich extracts (C-ARE and RG-ARE) were selected to be tested on normal and melanoma cell lines, due to their different chemical pattern. C-ARE composition consists of cyanidin aglycone glycosylated with different sugars; while RG-ARE contains glucosylated derivatives of five different aglycones. Both C-ARE and RG-ARE anthocyanins reduced proliferation, increased oxidative stress biomarkers and diminished mitochondrial membrane potential in melanoma cells, having no negative influence on normal cells. A synergistic response may be attributed to the five different aglycones present in RG-ARE, which proved to exert greater effects on melanoma cells than the mixture of cyanidin derivatives with different sugars (C-ARE). In conclusion, C-ARE and RG-ARE anthocyanins may inhibit melanoma cell proliferation and increase the level of oxidative stress, with opposite effect on normal cells. Therefore, anthocyanins might be recommended as active ingredients for cosmetic and nutraceutical industry. Graphical Abstract ᅟ.

Palmitic Acid: Physiological Role, Metabolism and Nutritional Implications

Palmitic acid (PA) has been for long time negatively depicted for its putative detrimental health effects, shadowing its multiple crucial physiological activities. PA is the most common saturated fatty acid accounting for 20–30% of total fatty acids in the human body and can be provided in the diet or synthesized endogenously via de novo lipogenesis (DNL). PA tissue content seems to be controlled around a well-defined concentration, and changes in its intake do not influence significantly its tissue concentration because the exogenous source is counterbalanced by PA endogenous biosynthesis. Particular physiopathological conditions and nutritional factors may strongly induce DNL, resulting in increased tissue content of PA and disrupted homeostatic control of its tissue concentration. The tight homeostatic control of PA tissue concentration is likely related to its fundamental physiological role to guarantee membrane physical properties but also to consent protein palmitoylation, palmitoylethanolamide (PEA) biosynthesis, and in the lung an efficient surfactant activity. In order to maintain membrane phospholipids (PL) balance may be crucial an optimal intake of PA in a certain ratio with unsaturated fatty acids, especially PUFAs of both n-6 and n-3 families. However, in presence of other factors such as positive energy balance, excessive intake of carbohydrates (in particular mono and disaccharides), and a sedentary lifestyle, the mechanisms to maintain a steady state of PA concentration may be disrupted leading to an over accumulation of tissue PA resulting in dyslipidemia, hyperglycemia, increased ectopic fat accumulation and increased inflammatory tone via toll-like receptor 4. It is therefore likely that the controversial data on the association of dietary PA with detrimental health effects, may be related to an excessive imbalance of dietary PA/PUFA ratio which, in certain physiopathological conditions, and in presence of an enhanced DNL, may further accelerate these deleterious effects.

Bcl-xL knockout attenuates mitochondrial respiration and causes oxidative stress that is compensated by pentose phosphate pathway activity

Bcl-x_L is an anti-apoptotic protein that localizes to the outer mitochondrial membrane and influences mitochondrial bioenergetics by controlling Ca²⁺ influx into mitochondria. Here, we analyzed the effect of mitochondrial Bcl-x_L on mitochondrial shape and function in knockout (KO), wild type and rescued mouse embryonic fibroblast cell lines. Mitochondria of KO cells were more fragmented, exhibited a reduced ATP concentration, and reduced oxidative phosphorylation (OXPHOS) suggesting an increased importance of ATP generation by other means. Under steady-state conditions, acidification of the growth medium as a readout for glycolysis was similar, but upon inhibition of ATP synthase with oligomycin, KO cells displayed an instant increase in glycolysis. In addition, forced energy production through OXPHOS by replacing glucose with galactose in the growth medium rendered KO cells more susceptible to mitochondrial toxins. KO cells had increased cellular reactive oxygen species and were more susceptible to oxidative stress, but had higher glutathione levels, which were however more rapidly consumed under conditions of oxidative stress. This coincided with an increased activity and protein abundance of the pentose phosphate pathway protein glucose-6-phosphate dehydrogenase, which generates NADPH necessary to regenerate reduced glutathione. KO cells were also less susceptible to pharmacological inhibition of the pentose phosphate pathway. We conclude that mitochondrial Bcl-x_L is involved in maintaining mitochondrial respiratory capacity. Its deficiency causes oxidative stress, which is associated with an increased glycolytic capacity and balanced by an increased activity of the pentose phosphate pathway.

Apoptotic Cells Induced Signaling for Immune Homeostasis in Macrophages and Dendritic Cells

Inefficient and abnormal clearance of apoptotic cells (efferocytosis) contributes to systemic autoimmune disease in humans and mice, and inefficient chromosomal DNA degradation by DNAse II leads to systemic polyarthritis and a cytokine storm. By contrast, efficient clearance allows immune homeostasis, generally leads to a non-inflammatory state for both macrophages and dendritic cells (DCs), and contributes to maintenance of peripheral tolerance. As many as 3 × 10⁸ cells undergo apoptosis every hour in our bodies, and one of the primary “eat me” signals expressed by apoptotic cells is phosphatidylserine (PtdSer). Apoptotic cells themselves are major contributors to the “anti-inflammatory” nature of the engulfment process, some by secreting thrombospondin-1 (TSP-1) or adenosine monophosphate and possibly other immune modulating “calm-down” signals that interact with macrophages and DCs. Apoptotic cells also produce “find me” and “tolerate me” signals to attract and immune modulate macrophages and DCs that express specific receptors for some of these signals. Neither macrophages nor DCs are uniform, and each cell type may variably express membrane proteins that function as receptors for PtdSer or for opsonins like complement or opsonins that bind to PtdSer, such as protein S and growth arrest-specific 6. Macrophages and DCs also express scavenger receptors, CD36, and integrins that function via bridging molecules such as TSP-1 or milk fat globule-EGF factor 8 protein and that differentially engage in various multi-ligand interactions between apoptotic cells and phagocytes. In this review, we describe the anti-inflammatory and pro-homeostatic nature of apoptotic cell interaction with the immune system. We do not review some forms of immunogenic cell death. We summarize the known apoptotic cell signaling events in macrophages and DCs that are related to toll-like receptors, nuclear factor kappa B, inflammasome, the lipid-activated nuclear receptors, Tyro3, Axl, and Mertk receptors, as well as induction of signal transducer and activator of transcription 1 and suppressor of cytokine signaling that lead to immune system silencing and DC tolerance. These properties of apoptotic cells are the mechanisms that enable their successful use as therapeutic modalities in mice and humans in various autoimmune diseases, organ transplantation, graft-versus-host disease, and sepsis.

MYC and AMPK-Save Energy or Die!

MYC sustains non-stop proliferation by altering metabolic machinery to support growth of cell mass. As part of the metabolic transformation MYC promotes lipid, nucleotide and protein synthesis by hijacking citric acid cycle to serve biosynthetic processes, which simultaneously exhausts ATP production. This leads to the activation of cellular energy sensing protein, AMP-activated protein kinase (AMPK). Cells with normal growth control can stop cell proliferation machinery to replenish ATP reservoirs whereas MYC prevents such break by blocking the cell cycle exit. The relentless cell cycle activation, accompanied by sustained metabolic stress and AMPK activity, switches the energy-saving AMPK to pro-apoptotic AMPK. The AMPK-involving metabolic side of MYC apoptosis may provide novel avenues for therapeutic development. Here we first review the role of anabolic MYC and catabolic AMPK pathways in context of cancer and then discuss how the concomitant activity of both pathways in tumor cells may result in targetable synthetic lethal vulnerabilities.

Transcription factor NF-kappa B represses ANT1 transcription and leads to mitochondrial dysfunctions

Mitochondria are intracellular organelles involved in cell survival and death, and dysfunctions of mitochondria are related to neurodegenerative diseases. As the most abundant protein in the mitochondrial inner membrane, adenine nucleotide translocator 1 (ANT1) plays a critical role in mitochondrial function, including the exchange of adenosine triphosphate/adenosine diphosphate (ATP/ADP) in mitochondria, basal proton leak and mitochondrial permeability transition pore (mPTP). Here, we show that ANT1 transcription is regulated by transcription factor NF-kappa B (NF-κB). NF-κB is bound to two NF-κB responsive elements (NREs) located at +1 to +20 bp and +41 to +61 bp in the ANT1 promoter. An NF-κB signalling stimulator, tumour necrosis factor alpha (TNFα), suppresses ANT1 mRNA and protein expression. Activation of NF-κB by TNFα impairs ATP/ADP exchange and decreases ATP production in mitochondria. Activation of NF-κB by TNFα decreases calcium induced mPTP opening, elevates mitochondrial potential and increases reactive oxygen species (ROS) production in both T98G human glioblastoma cells and rat cortical neurons. These results demonstrate that NF-κB signalling may repress ANT1 gene transcription and impair mitochondrial functions.

Cinnamomum cassia essential oil and its major constituent cinnamaldehyde induced cell cycle arrest and apoptosis in human oral squamous cell carcinoma HSC-3 cells

Cinnamomum cassia essential oil (CC-EO) has various functional properties, such as anti-microbial, hypouricemic, anti-tyrosinase and anti-melanogenesis activities. The present study aimed to evaluate the anti-cancer activities of CC-EO and its major constituent, cinnamaldehyde, in human oral squamous cell carcinoma HSC-3 cells. Determination of the cell viability, apoptotic characteristics, DNA damage, cell cycle analysis, reactive oxygen species (ROS) production, mitochondrial membrane potential, cytosolic Ca²⁺ level and intracellular redox status were performed. Our results demonstrated that CC-EO and cinnamaldehyde significantly decreased cell viability and caused morphological changes. The cell cycle analysis revealed that CC-EO and cinnamaldehyde induced G2/M cell cycle arrest in HSC-3 cells. The apoptotic characteristics (DNA laddering and chromatin condensation) and DNA damage were observed in the CC-EO-treated and cinnamaldehyde-treated HSC-3 cells. Moreover, CC-EO and cinnamaldehyde promoted an increase in cytosolic Ca²⁺ levels, induced mitochondrial dysfunction and activated cytochrome c release. The results of ROS production and intracellular redox status demonstrated that CC-EO and cinnamaldehyde significantly increased the ROS production and thiobarbituric acid reactive substance levels, and the cellular glutathione content and glutathione peroxidase activity were significantly reduced in HSC-3 cells. Our results suggest that CC-EO and cinnamaldehyde may possess anti-oral cancer activity in HSC-3 cells. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 456-468, 2017.

Adenosine receptors: regulatory players in the preservation of mitochondrial function induced by ischemic preconditioning of rat liver

Although adenosine A₁ receptors (A1R) have been associated to ischemic preconditioning (IPC), direct evidence for their ability to preserve mitochondrial function upon hepatic preconditioning is still missing and could represent a novel strategy to boost the quality of liver transplants. We tested if the A1R antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) prevented IPC in the liver and if the A1R agonist 2-chloro-N⁶-cyclopentyladenosine (CCPA) might afford a pharmacological preconditioning. Livers underwent a 120 min of 70% warm ischemia and 16 h of reperfusion (I/R), and the IPC group underwent a 5-min ischemic episode followed by a 10-min period of reperfusion before I/R. DPCPX or CCPA was administered intraperitoneally 2 h before IPC or I/R. The control of mitochondrial function emerged as the central element affected by IPC and controlled by endogenous A1R activation. Thus, livers from IPC- or CCPA-treated rats displayed an improved oxidative phosphorylation with higher state 3 respiratory rate, higher respiratory control ratio, increased ATP content, and decreased lag phase. IPC and CCPA also prevented the I/R-induced susceptibility to calcium-induced mitochondrial permeability transition, the rate of reactive oxygen species (ROS) generation, and the decreased mitochondrial content of phospho-Ser⁹ GSK-3β. DPCPX abrogated these effects of IPC. These implicate the control of GSK-3β activity by Akt-mediated Ser⁹-GSK-3β phosphorylation preserving the efficiency of oxidative phosphorylation and ROS-mediated cell death in the ability of A1R activation to mimic IPC in the liver. In conclusion, the parallel between IPC and A1R-mediated preconditioning also paves the way to consider a putative therapeutic use of the later in liver transplants.

Why is an energy metabolic defect the common outcome in BMFS?

Inherited bone marrow failure syndromes (BMFS) are rare, distressing, inherited blood disorders of children. Although the genetic origin of these pathologies involves genes with different functions, all are associated with progressive haematopoietic impairment and an excessive risk of malignancies. Defects in energy metabolism induce oxidative stress, impaired energy production and an unbalanced ratio between ATP and AMP. This assumes an important role in self-renewal and differentiation in haematopoietic stem cells (HSC) and can play an important role in bone marrow failure. Defects in energetic/respiratory metabolism, in particular in FA and SDS cells, have been described recently and seem to be a pertinent argument in the discussion of the haematopoietic defect in BMFS, as an alternative to the hypotheses already established on this subject, which may shed new light on the evolution of these diseases.

Biophysical changes reduce energetic demand in growth factor-deprived lymphocytes

Changes to the biophysical properties of lymphocytes are identified as an adaptive response to acute nutrient stress that occurs before the induction of autophagy.

Cytokine regulation of lymphocyte growth and proliferation is essential for matching nutrient consumption with cell state. Here, we examine how cellular biophysical changes that occur immediately after growth factor depletion promote adaptation to reduced nutrient uptake. After growth factor withdrawal, nutrient uptake decreases, leading to apoptosis. Bcl-x_L expression prevents cell death, with autophagy facilitating long-term cell survival. However, autophagy induction is slow relative to the reduction of nutrient uptake, suggesting that cells must engage additional adaptive mechanisms to respond initially to growth factor depletion. We describe an acute biophysical response to growth factor withdrawal, characterized by a simultaneous decrease in cell volume and increase in cell density, which occurs before autophagy initiation and is observed in both FL5.12 Bcl-x_L cells depleted of IL-3 and primary CD8⁺ T cells depleted of IL-2 that are differentiating toward memory cells. The response reduces cell surface area to minimize energy expenditure while conserving biomass, suggesting that the biophysical properties of cells can be regulated to promote survival under conditions of nutrient stress.