Bcl-2 and Bax regulate the channel activity of the mitochondrial adenine nucleotide translocator

RhoA-ROCK2 signaling possesses complex pathophysiological functions in cancer progression and shows promising therapeutic potential

The Rho GTPase signaling pathway is responsible for cell-specific processes, including actin cytoskeleton organization, cell motility, cell division, and the transcription of specific genes. The implications of RhoA and the downstream effector ROCK2 in cancer epithelial-mesenchymal transition, migration, invasion, and therapy resistance associated with stem cells highlight the potential of targeting RhoA/ROCK2 signaling in therapy. Tumor relapse can occur due to cancer cells that do not fully respond to adjuvant chemoradiotherapy, targeted therapy, or immunotherapy. Rho signaling-mediated mitotic defects and cytokinesis failure lead to asymmetric cell division, allowing cells to form polyploids to escape cytotoxicity and promote tumor recurrence and metastasis. In this review, we elucidate the significance of RhoA/ROCK2 in the mechanisms of cancer progression and summarize their inhibitors that may improve treatment strategies.

Permeabilization of the outer mitochondrial membrane: Mechanisms and consequences

Permeabilization of the outer mitochondrial membrane is а physiological process that can allow certain molecules to pass through it, such as low molecular weight solutes required for cellular respiration. This process is also important for the development of various modes of cell death. Depending on the severity of this process, cells can die by autophagy, apoptosis, or necrosis/necroptosis. Distinct types of pores can be opened at the outer mitochondrial membrane depending on physiological or pathological stimuli, and different mechanisms can be activated in order to open these pores. In this comprehensive review, all these types of permeabilization, the mechanisms of their activation, and their role in various diseases are discussed.

Exploring the multifaceted role of adenosine nucleotide translocase 2 in cellular and disease processes: A comprehensive review

Adenosine nucleotide translocases (ANTs) are a family of proteins abundant in the inner mitochondrial membrane, primarily responsible for shuttling ADP and ATP across the mitochondrial membrane. Additionally, ANTs are key players in balancing mitochondrial energy metabolism and regulating cell death. ANT2 isoform, highly expressed in undifferentiated and proliferating cells, is implicated in the development and drug resistance of various tumors. We conduct a detailed analysis of the potential mechanisms by which ANT2 may influence tumorigenesis and drug resistance. Notably, the significance of ANT2 extends beyond oncology, with roles in non-tumor cell processes including blood cell development, gastrointestinal motility, airway hydration, nonalcoholic fatty liver disease, obesity, chronic kidney disease, and myocardial development, making it a promising therapeutic target for multiple pathologies. To better understand the molecular mechanisms of ANT2, this review summarizes the structural properties, expression patterns, and basic functions of the ANT2 protein. In particular, we review and analyze the controversy surrounding ANT2, focusing on its role in transporting ADP/ATP across the inner mitochondrial membrane, its involvement in the composition of the mitochondrial permeability transition pore, and its participation in apoptosis.

Orexins in apoptosis: a dual regulatory role

The orexins, also referred to as hypocretins, are neuropeptides that originate from the lateral hypothalamus (LH) region of the brain. They are composed of two small peptides, orexin-A, and orexin-B, which are broadly distributed throughout the central and peripheral nervous systems. Orexins are recognized to regulate diverse functions, involving energy homeostasis, the sleep-wake cycle, stress responses, and reward-seeking behaviors. Additionally, it is suggested that orexin-A deficiency is linked to sleepiness and narcolepsy. The orexins bind to their respective receptors, the orexin receptor type 1 (OX1R) and type 2 (OX2R), and activate different signaling pathways, which results in the mediation of various physiological functions. Orexin receptors are widely expressed in different parts of the body, including the skin, muscles, lungs, and bone marrow. The expression levels of orexins and their receptors play a crucial role in apoptosis, which makes them a potential target for clinical treatment of various disorders. This article delves into the significance of orexins and orexin receptors in the process of apoptosis, highlighting their expression levels and their potential contributions to different diseases. The article offers an overview of the existing understanding of the orexin/receptor system and how it influences the regulation of apoptosis.

N-nitrosodimethylamine exposure to zebrafish embryos/larvae causes cardiac and spinal developmental toxicity

N-nitrosodimethylamine (NDMA), one of the new nitrogen-containing disinfection by-products, is potentially cytotoxic, genotoxic, and carcinogenic. Its potential toxicological effects have attracted a wide range of attention, but the mechanism is still not sufficiently understood. To better understand the toxicological mechanisms of NDMA, zebrafish embryos were exposed to NDMA from 3 h post-fertilization (hpf) to 120hpf. Mortality and malformation were significantly increased, and hatching rate, heart rate, and swimming behavior were decreased in the exposure groups. The result indicated that NDMA exposure causes cardiac and spinal developmental toxicity. mRNA levels of genes involved in the apoptotic pathway, including p53, bax, and bcl-2 were significantly affected by NDMA exposure. Moreover, the genes associated with spinal and cardiac development (myh6, myh7, nkx2.5, eph, bmp2b, bmp4, bmp9, run2a, and run2b) were significantly downregulated after treatment with NDMA. Wnt and TGF-β signaling pathways, crucial for the development of diverse tissues and organs in the embryo and the establishment of the larval spine, were also significantly disturbed by NDMA treatment. In summary, the disinfection by-product, NDMA, exhibits spinal and cardiac developmental toxicity in zebrafish embryos, providing helpful information for comprehensive analyses and a better understanding the mechanism of its toxicity.

A review for cancer treatment with mushroom metabolites through targeting mitochondrial signaling pathway: In vitro and in vivo evaluations, clinical studies and future prospects for mycomedicine

Resistance to apoptosis stands as a roadblock to the successful pharmacological execution of anticancer drug effect. A comprehensive insight into apoptotic signaling pathways and an understanding of the mechanisms of apoptosis resistance are crucial to unveil new drug targets. At this juncture, researchers are heading towards natural sources in particular, mushroom as their potential drugs leads to being the reliable source of potent bioactive compounds. Given the continuous increase in cancer cases, the potent anticancer efficacy of mushrooms has inevitably become a fascinating object to researchers due to their higher safety margin and multitarget. This review aimed to collect and summarize all the available scientific data on mushrooms from their extracts to bioactive molecules in order to suggest their anticancer attributes via a mitochondrion -mediated intrinsic signaling mechanism. Compiled data revealed that bioactive components of mushrooms including polysaccharides, sterols and terpenoids as well as extracts prepared using 15 different solvents from 53 species could be effective in the supportive treatment of 20 various cancers. The underlying therapeutic mechanisms of the studied mushrooms are explored in this review through diverse and complementary investigations: in vitro assays, pre-clinical studies and clinical randomized controlled trials. The processes mainly involved were ROS production, mitochondrial membrane dysfunction, and action of caspase 3, caspase 9, XIAP, cIAP, p53, Bax, and Bcl-2. In summary, the study provides facts pertaining to the potential beneficial effect of mushroom extracts and their active compounds against various types of cancer and is shedding light on the underlying targeted signaling pathways.

Ferroptosis: A new insight for treatment of acute kidney injury

Acute kidney injury (AKI), one of the most prevalent clinical diseases with a high incidence rate worldwide, is characterized by a rapid deterioration of renal function and further triggers the accumulation of metabolic waste and toxins, leading to complications and dysfunction of other organs. Multiple pathogenic factors, such as rhabdomyolysis, infection, nephrotoxic medications, and ischemia-reperfusion injury, contribute to the onset and progression of AKI. However, the detailed mechanism remains unclear. Ferroptosis, a recently identified mechanism of nonapoptotic cell death, is iron-dependent and caused by lipid peroxide accumulation in cells. A variety of studies have demonstrated that ferroptosis plays a significant role in AKI development, in contrast to other forms of cell death, such as apoptosis, necroptosis, and pyroptosis. In this review, we systemically summarized the definition, primary biochemical mechanisms, key regulators and associated pharmacological research progress of ferroptosis in AKI. We further discussed its therapeutic potential for the prevention of AKI, in the hope of providing a useful reference for further basic and clinical studies.

An Update to Hallmarks of Cancer

In the last decade, there has been remarkable progress in research toward understanding and refining the hallmarks of cancer. In this review, we propose a new hallmark - "pro-survival autophagy." The importance of pro-survival autophagy is well established in tumorigenesis, as it is related to multiple steps in cancer progression and vital for some cancers. Autophagy is a potential anti-cancer therapeutic target. For this reason, autophagy is a good candidate as a new hallmark of cancer. We describe two enabling characteristics that play a major role in enabling cells to acquire the hallmarks of cancer - "tumor-promoting microenvironment and macroenvironment" and "cancer epigenetics, genome instability and mutation." We also discuss the recent updates, therapeutic and prognostic implications of the eight hallmarks of cancer described by Hanahan et al. in 2011. Understanding these hallmarks and enabling characteristics is key not only to developing new ways to treat cancer efficiently but also to exploring options to overcome cancer resistance to treatment.

Effects of acute hypoxia and reoxygenation on oxygen sensors, respiratory metabolism, oxidative stress, and apoptosis in hybrid yellow catfish "Huangyou-1"

The regulation mechanism of the hybrid yellow catfish "Huangyou-1" was assessed under conditions of hypoxia and reoxygenation by examination of oxygen sensors and by monitoring respiratory metabolism, oxidative stress, and apoptosis. The expressions of genes related to oxygen sensors (HIF-1α, HIF-2α, VHL, HIF-1β, PHD2, and FIH-1) were upregulated in the brain and liver during hypoxia, and recovered compared with control upon reoxygenation. The expressions of genes related to glycolysis (HK1, PGK1, PGAM2, PFK, and LDH) were increased during hypoxia and then recovered compared with control upon reoxygenation. The mRNA levels of CS did not change during hypoxia in the brain and liver, but increased during reoxygenation. The mRNA levels of SDH decreased significantly only in the liver during hypoxia, but later increased compared with control upon reoxygenation in both tissues. Under hypoxic conditions, the expressions of genes related to oxidative stress (SOD1, SOD2, GSH-Px, and CAT) and the activity of antioxidant enzymes (SOD, CAT, and GSH-Px) and MDA were upregulated compared with control. The expressions of genes related to apoptosis (Apaf-1, Bax, Caspase 3, Caspase 9, and p53) were higher than those in control during hypoxic exposure, while the expressions of Bcl-2 and Cyt C were decreased. The findings of the transcriptional analyses will provide insights into the molecular mechanisms of hybrid yellow catfish "Huangyou-1" under conditions of hypoxia and reoxygenation. Overall, these findings showed that oxygen sensors of "Huangyou-1" are potentially useful biomarkers of environmental hypoxic exposure. Together with genes related to respiratory metabolism, oxidative stress and apoptosis occupy a quite high position in enhancing hypoxia tolerance. Our findings provided new insights into the molecular regulatory mechanism of hypoxia in "Huangyou-1."

Role of reactive oxygen species in tumors based on the 'seed and soil' theory: A complex interaction (Review)

Tumor microenvironment (TME) can serve as the 'soil' for the growth and survival of tumor cells and function synergically with tumor cells to mediate tumor progression and therapeutic resistance. Reactive oxygen species (ROS) is somewhat of a double‑edged sword for tumors. Accumulating evidence has reported that regulating ROS levels can serve an anti‑tumor role in the TME, including the promotion of cancer cell apoptosis, inhibition of angiogenesis, preventing immune escape, manipulating tumor metabolic reorganization and improving drug resistance. In the present review, the potential role of ROS in anti‑tumor therapy was summarized, including the possibility of directly or indirectly targeting the TME.

The mitochondrial permeability transition pore: an evolving concept critical for cell life and death

In this review, we summarize current knowledge of perhaps one of the most intriguing phenomena in cell biology: the mitochondrial permeability transition pore (mPTP). This phenomenon, which was initially observed as a sudden loss of inner mitochondrial membrane impermeability caused by excessive calcium, has been studied for almost 50 years, and still no definitive answer has been provided regarding its mechanisms. From its initial consideration as an in vitro artifact to the current notion that the mPTP is a phenomenon with physiological and pathological implications, a long road has been travelled. We here summarize the role of mitochondria in cytosolic calcium control and the evolving concepts regarding the mitochondrial permeability transition (mPT) and the mPTP. We show how the evolving mPTP models and mechanisms, which involve many proposed mitochondrial protein components, have arisen from methodological advances and more complex biological models. We describe how scientific progress and methodological advances have allowed milestone discoveries on mPTP regulation and composition and its recognition as a valid target for drug development and a critical component of mitochondrial biology.

Cinnamon Extract and Probiotic Supplementation Alleviate Copper-Induced Nephrotoxicity via Modulating Oxidative Stress, Inflammation, and Apoptosis in Broiler Chickens

The present study aimed to assess the potential protective effects of cinnamon (Cinnamomum zeylanicum, Cin) and probiotic against CuSO4-induced nephrotoxicity in broiler chickens. One-day-old Cobb chicks were assigned into seven groups (15 birds/group): control group, fed basal diet; Cin group, fed the basal diet mixed with Cin (200 mg/kg); PR group, receiving PR (1 g/4 L water); Cu group, fed the basal diets mixed with CuSO4 (300 mg/kg); Cu + Cin group; Cu + PR group; and Cu + Cin + PR group. All treatments were given daily for 6 weeks. Treatment of Cu-intoxicated chickens with Cin and/or PR reduced (p < 0.05) Cu contents in renal tissues and serum levels of urea, creatinine, and uric acid compared to the Cu group. Moreover, Cin and PR treatment decreased lipid peroxidation and increased antioxidant enzyme activities in chickens' kidney. Additionally, significant reduction (p < 0.05) in the mRNA expression of tumor necrosis factor alpha (TNF-α), interleukin (IL-2) and Bax, and in cyclooxygenase (COX-II) enzyme expression, and significant elevation (p < 0.05) in mRNA expression of IL-10 and Bcl-2 were observed in kidneys of Cu + Cin, Cu + PR, and Cu + Cin + PR groups compared to Cu group. Conclusively, Cin and/or PR afford considerable renal protection against Cu-induced nephrotoxicity in chickens.

BCL(X)L and BCL2 increase the metabolic fitness of breast cancer cells: a single-cell imaging study

The BCL2 family of proteins regulate apoptosis by controlling mitochondrial outer membrane permeability. However, the effects on mitochondrial structure and bioenergetics have also been reported. Here we comprehensively characterized the effects of BCL2 and BCL(X)L on cellular energetics in MCF7 breast cancer cells using time-lapse confocal single-cell imaging and mitochondrial and cytosolic FRET reporters. We found that BCL2 and BCL(X)L increase the metabolic robustness of MCF7 cells, and that this was associated with increased mitochondrial NAD(P)H and ATP levels. Experiments with the F₁F₀ synthase inhibitor oligomycin demonstrated that BCL2 and in particular BCL(X)L, while not affecting ATP synthase activity, more efficiently coupled the mitochondrial proton motive force with ATP production. This metabolic advantage was associated with an increased resistance to nutrient deprivation and enhanced clonogenic survival in response to metabolic stress, in the absence of profound effects on cell death. Our data suggest that a primary function of BCL(X)L and BCL2 overexpression in tumor cells is to increase their resistance to metabolic stress in the tumor microenvironment, independent of cell death signaling.

The molecular mechanism of a novel derivative of BTO-956 induced apoptosis in human myelomonocytic lymphoma cells

Acute myeloid leukemia (AML) is a malignant cancer of the hematopoietic system. Although the effectiveness of arsenic compounds has been recognized and applied clinically, some patients are still found resistant to this chemotherapy. In this study, we investigated that a synthetic thyroid hormone analog (TA), 2-iodo-4-nitro-1-(o-tolyloxy) benzene, had a strong apoptosis effect on U937 cells. U937 cells were treated with TA, and examinted the generation of reactive oxygen species (ROS), dysfunction of mitochondria, expression of pro-apoptosis and anti-apoptosis, and cleavage of caspase-3 and Poly (ADP-ribose) polymerase (PARP). Further, it is also evaluated that insight molecular mechanism and signaling pathways involved in the study. It is found that TA significantly induced apoptosis in U937 cells through production of ROS, dysfunction of mitochondria, and activation of caspase cascade. It was also observed that MAPK signaling pathway including ERK, JNK, and P38 signals are involved in the induction of apoptosis. Moreover, marked activation of autophagy and ER stress markers such as LC3, P62, Beclin1 and GRP78, CHOP were observed, respectively. Pretreatment with ER stress inhibitor tauroursodeoxycholic acid (TUDCA) and autophagy inhibitor 3-Methyladenine (3-MA) have successfully attenuated and aggravated TA-induced apoptosis, respectively. We further confirmed the active involvement of ER stress and autophagy signals. In conclusion, TA induced apoptosis through ER stress and activation of autophagy, and the latter is not conducive to TA-induced cell death. Our results may provide a new insight into the strategic development of novel therapy for the treatment of AML.

Recent progress in the use of mitochondrial membrane permeability transition pore in mitochondrial dysfunction-related disease therapies

Mitochondria have various cellular functions, including ATP synthesis, calcium homeostasis, cell senescence, and death. Mitochondrial dysfunction has been identified in a variety of disorders correlated with human health. Among the many underlying mechanisms of mitochondrial dysfunction, the opening up of the mitochondrial permeability transition pore (mPTP) is one that has drawn increasing interest in recent years. It plays an important role in apoptosis and necrosis; however, the molecular structure and function of the mPTP have still not been fully elucidated. In recent years, the abnormal opening up of the mPTP has been implicated in the development and pathogenesis of diverse diseases including ischemia/reperfusion injury (IRI), neurodegenerative disorders, tumors, and chronic obstructive pulmonary disease (COPD). This review provides a systematic introduction to the possible molecular makeup of the mPTP and summarizes the mitochondrial dysfunction-correlated diseases and highlights possible underlying mechanisms. Since the mPTP is an important target in mitochondrial dysfunction, this review also summarizes potential treatments, which may be used to inhibit pore opening up via the molecules composing mPTP complexes, thus suppressing the progression of mitochondrial dysfunction-related diseases.

The Role of Adenine Nucleotide Translocase in the Mitochondrial Permeability Transition

The mitochondrial permeability transition, a Ca2+-induced significant increase in permeability of the inner mitochondrial membrane, plays an important role in various pathologies. The mitochondrial permeability transition is caused by induction of the permeability transition pore (PTP). Despite significant effort, the molecular composition of the PTP is not completely clear and remains an area of hot debate. The Ca2+-modified adenine nucleotide translocase (ANT) and F0F1 ATP synthase are the major contenders for the role of pore in the PTP. This paper briefly overviews experimental results focusing on the role of ANT in the mitochondrial permeability transition and proposes that multiple molecular entities might be responsible for the conductance pathway of the PTP. Consequently, the term PTP cannot be applied to a single specific protein such as ANT or a protein complex such as F0F1 ATP synthase, but rather should comprise a variety of potential contributors to increased permeability of the inner mitochondrial membrane.

ANTs and cancer: Emerging pathogenesis, mechanisms, and perspectives

Adenine nucleotide translocases (ANTs) are a class of transporters located in the inner mitochondrial membrane that not only couple processes of cellular productivity and energy expenditure, but are also involved in the composition of the mitochondrial membrane permeability transition pore (mPTP). The function of ANTs has been found to be most closely related to their own conformational changes. Notably, as multifunctional proteins, ANTs play a key role in oncogenesis, which provides building blocks for tumor anabolism, control oxidative phosphorylation and glycolysis homeostasis, and govern cell death. Thus, ANTs constitute promising targets for the development of novel anticancer agents. Here, we review the recent findings regarding ANTs and their important mechanisms in cancer, with a focus on the therapeutic potential of targeting ANTs for cancer therapy.

Oxidative stress-mediated mitochondrial pathway-dependent apoptosis is induced by silica nanoparticles in H9c2 cardiomyocytes

The use of silica nanoparticles (SiNPs) is increasing in popularity; however, the emissions released during manufacturing, use and during the disposal stages potentially harm the environment. SiNPs can enter the body and cause cardiac toxicity indirectly or directly. However, toxicological data on SiNPs in cardiac cells in vitro, and the detailed molecular mechanisms by which damage is caused remain unclear. In the present study, oxidative stress-mediated apoptosis and cytotoxicity induced by SiNPs in H9c2 cells were examined. H9c2 cells were used to explore the mechanisms of toxicity by treating cells with 0, 25, 50, 100, and 200 µg/ml SiNPs, with and without 3 mM of the reactive oxygen species (ROS) scavenger, N-acetyl-l-cysteine (NAC), for 24 h. The results showed that SiNPs decreased cell viability and proliferation by increasing the release of lactate dehydrogenase (LDH) and inducing apoptosis in H9c2 cells. ROS levels were significantly increased in a dose-dependent manner. Additionally, the levels of superoxide dismutase (SOD), glutathione (GSH), and GSH-peroxidase (Px) were significantly decreased following exposure to SiNPs. Treatment with NAC attenuated LDH release; the levels of ROS, SOD, GSH, and GSH-Px production were increased, and SiNPs-induced mitochondrial pathway-dependent apoptosis was reduced. These results demonstrate that apoptosis and cytotoxicity induced by SiNPs in H9c2 cells are a result of ROS-mediated oxidative stress. These data suggest that exposure to SiNPs is a potential risk factor for cardiovascular disease.

Alpha-lipoic acid ameliorates H2O2-induced human vein endothelial cells injury via suppression of inflammation and oxidative stress

The study was aimed to investigate the effect of alpha-lipoic acid (ALA) on human umbilical vein endothelial cells (HUVECs) injury induced by hydrogen peroxide (H₂O₂) and to explore its possible mechanisms. We established the H₂O₂-induced HUVECs injury model and the ALA treatment groups in which HUVECs were co-incubated with H₂O₂ (250 μmol/L) and different final concentrations of ALA (100,200,400 μmol/L) for 48 h. Cell survival rate assay and LDH activity assay were carried out. The levels of related proteins were performed by Western Blot. We observed that H₂O₂ administration resulted in an increase in the LDH activity and a decrease in cell survival rate. The expression levels of Nox4, Bax, NF-κB p65, Caspase-9, Caspase-3, iNOS, VCAM-1 and ICAM-1 were up-regulated, while the expression level of Bcl-2 was down-regulated. All these factors were significantly improved by ALA treatment. In brief, ALA treatment ameliorates H₂O₂-induced HUVECs damage by inhibiting inflammation and oxidative stress.

A 20/20 view of ANT function in mitochondrial biology and necrotic cell death

The adenosine nucleotide translocase (ANT) family of proteins are inner mitochondrial membrane proteins involved in energy homeostasis and cell death. The primary function of ANT proteins is to exchange cytosolic ADP with matrix ATP, facilitating the export of newly synthesized ATP to the cell while providing new ADP substrate to the mitochondria. As such, the ANT proteins are central to maintaining energy homeostasis in all eukaryotic cells. Evidence also suggests that the ANTs constitute a pore-forming component of the mitochondrial permeability transition pore (MPTP), a structure that forms in the inner mitochondrial membrane that is thought to underlie regulated necrotic cell death. Additionally, emerging studies suggest that ANT proteins are also critical for mitochondrial uncoupling and for promoting mitophagy. Thus, the ANTs are multifunctional proteins that are poised to participate in several aspects of mitochondrial biology and the greater regulation of cell death, which will be discussed here.

The mystery of mitochondria-ER contact sites in physiology and pathology: A cancer perspective

Mitochondria-associated membranes (MAM), physical platforms that enable communication between mitochondria and the endoplasmic reticulum (ER), are enriched with many proteins and enzymes involved in several crucial cellular processes, such as calcium (Ca²⁺) homeostasis, lipid synthesis and trafficking, autophagy and reactive oxygen species (ROS) production. Accumulating studies indicate that tumor suppressors and oncogenes are present at these intimate contacts between mitochondria and the ER, where they influence Ca²⁺ flux between mitochondria and the ER or affect lipid homeostasis at MAM, consequently impacting cell metabolism and cell fate. Understanding these fundamental roles of mitochondria-ER contact sites as important domains for tumor suppressors and oncogenes can support the search for new and more precise anticancer therapies. In the present review, we summarize the current understanding of basic MAM biology, composition and function and discuss the possible role of MAM-resident oncogenes and tumor suppressors.

Nodularin induced oxidative stress contributes to developmental toxicity in zebrafish embryos

Nodularin (NOD) is a kind of cyanobacterial toxins. It is of concern due to elicit severe genotoxicity in humans and animals. The comprehensive evaluation of NOD-induced adverse effects in living organisms is urgently needed. This study is aimed to report the developmental toxicity and molecular mechanism using zebrafish embryos exposed to NOD. The embryonic toxicity induced by NOD is demonstrated by inhibition of embryo hatching, increase in mortality rate, abnormal heart rate, embryonic malformation as well as defects in angiogenesis and common cardinal vein remodeling. NOD triggered a decreased rate of angiogenesis through inhibiting endothelial cells migration. NOD induced embryonic cell apoptosis and DNA damage, which can be alleviated by antioxidant N-acetyl-L-cysteine. NOD significantly caused oxidative damage as indicated by changes in reactive oxygen species, superoxide dismutase, catalase, glutathione and malondialdehyde. NOD also altered the expression of vascular development-genes (DLL4, CDH5, VEGFA, VEGFC) and apoptosis-related genes (BAX, BCL-2, P53, CASPASE 3). Taken together, NOD induced adverse effect on zebrafish embryos development, which may be associated with oxidative stress and apoptosis through the activation of P53-BAX/BCL-2-CASPASE 3-mediated pathway.

Advances in Characterizing Recently-Identified Molecular Actions of Melatonin: Clinical Implications

Melatonin, N-acetyl-5-methoxy-tryptamine, was discovered to be a product of serotonin metabolism in the mammalian pineal gland where its synthesis is under control of the light:dark cycle. Besides its regulatory pathway involving ganglion cells in the retina, the neural connections between the eyes and the pineal gland include the master circadian clock, the suprachiasmatic nuclei, and the central and peripheral nervous systems. Since pineal melatonin is released into the blood and into the cerebrospinal fluid, it has access to every cell in an organism and it mediates system-wide effects. Subsequently, melatonin was found in several extrapineal organs and, more recently, perhaps in every cell of every organ. In contrast to the pinealocytes, non-pineal cells do not discharge melatonin into the blood; rather it is used locally in an intracrine, autocrine, or paracrine manner. Melatonin levels in non-pineal cells do not exhibit a circadian rhythm and do not depend on circulating melatonin concentrations although when animals are treated with exogenous melatonin it is taken up by presumably all cells. Mitochondria are the presumed site of melatonin synthesis in all cells; the enzymatic machinery for melatonin synthesis has been identified in mitochondria. The association of melatonin with mitochondria, because of its ability to inhibit oxidative stress, is very fortuitous since these organelles are a major site of damaging reactive oxygen species generation. In this review, some of the actions of non-pineal-derived melatonin are discussed in terms of cellular and subcellular physiology.

Mechanism of cell death induced by silica nanoparticles in hepatocyte cells is by apoptosis

Silicon is one of the most widely used chemical materials, and the increasing use of silica nanoparticles (SNs) highlights the requirement for safety and biological toxicity studies. The damaging and adverse effects of SNs on human hepatocytes remain largely unknown, as do the mechanisms involved. In the present study, the mechanisms underlying SN‑induced toxicity in the human hepatocyte cell line HL‑7702 were investigated. An MTT assay revealed that following exposure to SNs in the concentration range of 25‑200 µg/ml, the viability of HL‑7702 cells decreased, and the viability decreased further with increasing exposure time. SNs induced a delay in the S and G2/M phases of the cell cycle, and also induced DNA damage in these cells. Western blot and flow cytometry analyses revealed that cell death was mediated by mitochondrial damage and the upregulated expression of a number of pro‑apoptotic proteins. In conclusion, exposure to SNs led to mitochondrial and DNA damage, resulting in apoptosis‑mediated HL‑7702 cell death. The study provided evidence for the cellular toxicity of SNs, and added to the growing body of evidence regarding the potential damaging effects of nanoparticles, indicating that caution should be exercised in their widespread usage.

Hepatorenal protective effects of taurine and N-acetylcysteine against fipronil-induced injuries: The antioxidant status and apoptotic markers expression in rats

Fipronil (FPN), a commonly used phenylpyrazole pesticide can induce oxidative tissue damage following hazard usage. Due to the extensive household and commercial usage of FPN, its toxic effects on mammals received considerable attention. Finding the proper antioxidant that can overcome FPN-induced damage is essential. Therefore, the present study aimed to assess the hepatorenal ameliorative outcomes of N-acetyl cysteine (NAC) and taurine (TAU) against hepatorenal damage induced by FPN in male Wistar rats. Compared to control rats, oral FPN (at a dose of 19.4 mg kg-1 BW for five successive days) significantly increased serum activities (p ≤ 0.05) of alkaline phosphatase, lactate dehydrogenase and transaminases, in addition to total cholesterol, urea and creatinine levels. Moreover, FPN provoked oxidative damage indicated by increased malondialdehyde and nitric oxide formation and decreased glutathione concentration and activities of enzymatic antioxidants (superoxide dismutase, glutathione peroxidase and catalase) in the hepatic and renal tissues. Furthermore, FPN administration induced overexpression of the proapoptotic (Bax), while it downregulated the expression of the anti-apoptotic (Bcl-2) protein. Interestingly, oral administration of TAU (50 mg Kg-1 BW) and NAC (50 mg Kg-1 BW), alone or in combination, five days prior to and five days along with FPN administration, significantly ameliorated (p ≤ 0.05) and normalized the harmful effects of FPN on serum biomarkers of hepatorenal injury, lipid peroxidation and tissue antioxidants. In conclusion, TAU and NAC, alone or in combination, provided significant hepatorenal protection against oxidative stress and apoptosis induced by FPN.

Azilsartan and its Zn(II) complex. Synthesis, anticancer mechanisms of action and binding to bovine serum albumin

Azilsartan is the eighth approved member of angiotensin II receptor blockers for hypertension treatment. Considering that some drugs have additional effects when administered, we studied its effects and mechanisms of action on a human lung cancer cell line A549. We have also modified the structure of the drug by complexation with Zn(II) cation and assayed the anticancer effect. The crystal structure of the new binuclear Zn(II) complex, for short [Zn₂(azil)₂(H₂O)₄]·2H₂O (ZnAzil), was determined by X-ray diffraction methods. The zinc ions are bridged by azilsartan ligands through their carboxylate oxygen and oxadiazol nitrogen atoms. The compounds were examined for their cytotoxic effects against human lung fibroblast (MRC5) and human lung cancer (A549) cell lines. Azilsartan displayed low cytotoxic effects at 150 μM concentrations in A549 human lung cancer cells but the higher effect measured for the Zn complex suggested that this compound may act as an anticancer agent. An apoptotic oxidative stress mechanism of action via the mitochondrial-dependent intrinsic pathway has been determined. Besides, the compounds exerted weak cytotoxic effects in the normal lung related cell line MRC5. Binding constants of the complex formed between each compound and bovine serum albumin (BSA) are in the intermediate range, hence suggesting that azilsartan and ZnAzil could be bonded and transported by BSA.

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.

RhoA regulates resistance to irinotecan by regulating membrane transporter and apoptosis signaling in colorectal cancer

Colorectal cancer (CRC) is a major cause of mortality and morbidity worldwide. While surgery remains the mainstay of treatment in early stage CRC, chemotherapy is usually given to prolong the overall survival and improve the quality of life for metastatic colorectal cancer (mCRC). But drug resistance is one of the major hurdles of mCRC treatment, and the underlying mechanisms are still largely unknown. In this study, we show that, compared with parental cells, RhoA is up-regulated in irinotecan (CPT-11)-resistant CRC cells. Furthermore, inhibition of RhoA in drug resistant cells, at least partially, rescues the resistance against irinotecan and increases the sensitivity to other chemotherapeutic drug by inhibiting expression of MDR1, MRP1and GSTP1, promotes apoptosis by suppressing the expression of BCL-XL and Bcl-2 and increasing Bax expression, and significantly decreases side population cells. Our results suggest that, in addition to survival, proliferation, migration, adhesion, cell cycle and gene transcription, RhoA is also involved in chemoresistance by regulating the expression of membrane transporter and apoptosis protein in colorectal cancer. They raise an interesting possibility that the expression of RhoA may indicate a poor prognosis due to the high probability to therapy resistance and, on the other hand, inhibition of RhoA activity and function may overcome chemoresistance and improve the effectiveness of clinical treatment of CRC.

Effect of ATP and Bax on the apoptosis of Eimeria tenella host cells

Background

Eimeria tenella (E. tenella) is a species of Eimeria that causes haemorrhagic caecal coccidiosis, resulting in major economic losses in the global poultry industry. After E. tenella infection, the amount of ATP and Bax in host cells showed highly significant changes. Therefore, it is necessary to investigate the effects of ATP and Bax on the apoptosis of E. tenella host cells.

Results

The ATP-treated group and the V5-treated group had higher E. tenella infection rates than the untreated group at 24, 48, 72, 96, and 120 h after infection with E. tenella. The results of flow cytometry showed that compared with the control group, the mitochondrial permeability transition pore (MPTP) opening in the untreated group was highly significantly increased (P < 0.01) at 4, 24, 48, 72, 96, and 120 h. Moreover, results from Hoechst-Annexin V-PI staining and flow cytometry showed that the rates of early apoptosis, late apoptosis, and necrosis in the untreated group were significantly lower (P < 0.05) or highly significantly lower (P < 0.01) than those of the control group at 4 h, while the rates of early apoptosis, late apoptosis, and necrosis in the untreated group were higher at varying degrees than those in the control group at 24–120 h (P < 0.05 or P < 0.01). After treatment with ATP and Bax inhibitors, the rates of early apoptosis, late apoptosis, and necrosis, in addition to the MPTP opening in both the ATP-treated and V5-treated groups, were significantly lower (P < 0.05) or highly significantly lower (P < 0.01) than those in the untreated group.

Conclusions

ATP and Bax play important roles in regulating the apoptosis of E. tenella host cells.

Electronic supplementary material

The online version of this article (10.1186/s12917-017-1313-z) contains supplementary material, which is available to authorized users.

Association of down-regulation of calcitonin gene-related peptide and substance P with increase of myocardial vulnerability in diabetic neuropathic rats

Diabetic patients present high co-morbidities of neuropathy and severer consequences of coronary heart disease. But the pathological mechanism is still unclear. Here we investigated a potential association of diabetic impairment of sensory nerves with increase of vulnerability of myocardium in acute myocardial ischemia/reperfusion. A rat model of diabetes mellitus was induced by high fat and sugar diet plus a small dose of streptozotocin. Impairment of sensory nerves was evaluated by measurement of changes in tail flick latency to noxious thermal stimulation and calcitonin gene-related peptide (CGRP) and substance P (SP) in the dorsal root ganglia (DRG) and the myocardium of the heart were examined. The myocardial injury was examined by infarct size, apoptosis ratio of cardiomyocytes and cardiac troponin I in the animals underwent acute myocardial ischemia (for 30min) and reperfusion (for 120min). The effects of CGRP and SP on cardiomyocyte injury induced by high glucose and hypoxia/reoxygenation were tested in cultured myocytes. The diabetic animals presented significant elevation of noxious thermal threshold with obvious reduction of the contents of CGRP and SP in the DRG and the myocardium. Importantly, the diabetic animals showed significant increases of infarct size, myocyte apoptosis and serum cardiac troponin I after acute myocardial ischemia/reperfusion, compared to the non-diabetic control. Furthermore, exogenously administered CGRP and SP attenuated the myocyte injury induced by the high concentration of glucose and hypoxia/reoxygenation. These findings suggested that impairment of sensory nerves with significant reduction of CGRP and SP in DRG, ventricular myocardium and serum may be associated with increase of myocardial vulnerability in acute myocardial ischemia/reperfusion in streptozotocin-induced diabetic rats.

The regulator of calcineurin 1 increases adenine nucleotide translocator 1 and leads to mitochondrial dysfunctions

The over‐expression of regulator of calcineurin 1 isoform 1 (RCAN1.1) has been implicated in mitochondrial dysfunctions of Alzheimer's disease; however, the mechanism linking RCAN1.1 over‐expression and the mitochondrial dysfunctions remains unknown. In this study, we use human neuroblastoma SH‐SY5Y cells stably expressing RCAN1.1S and rat primary neurons infected with RCAN1.1S expression lentivirus to study the association of RCAN1 with mitochondrial functions. Our study here showed that the over‐expression of RCAN1.1S remarkably up‐regulates the expression of adenine nucleotide translocator (ANT1) by stabilizing ANT1 mRNA. The increased ANT1 level leads to accelerated ATP–ADP exchange rate, more Ca²⁺‐induced mitochondrial permeability transition pore opening, increased cytochrome c release, and eventually cell apoptosis. Furthermore, knockdown of ANT1 expression brings these mitochondria perturbations caused by RCAN1.1S back to normal. The effect of RCAN1.1S on ANT1 was independent of its inhibition on calcineurin. This study elucidated a novel function of RCAN1 in mitochondria and provides a molecular basis for the RCAN1.1S over‐expression‐induced mitochondrial dysfunctions and neuronal apoptosis.

Mitochondrial involvement in myocyte death and heart failure

As the heart is an energy-demanding organ, impaired cardiac energy metabolism and mitochondrial function have been inexorably linked to cardiac dysfunction. There is a growing recognition that mitochondrial dysfunction contributes to impaired myocardial energetics and increased oxidative stress in cardiomyopathies, cardiac ischemic damage and heart failure (HF), and mitochondrial permeability transition pore opening has been reported a critical trigger of myocyte death and myocardial remodeling. It is well established that mitochondria play pivotal roles in intracellular signaling in both cell death as well as in cardioprotective pathways. Moreover, recent studies have shown that defects in mitochondrial dynamics affecting biogenesis and turnover are linked to cardiac senescence and HF. Accordingly, there has been an increasing interest in targeting mitochondria for HF therapy. This article reviews the background and recent evidence of mitochondrial involvement in several types of cell death (apoptosis, necrosis and autophagy) occurring in HF. In addition, potential strategies for targeting mitochondria are examined, and their utility in HF therapy considered.

Alleviation of Lead-Induced Apoptosis by Puerarin via Inhibiting Mitochondrial Permeability Transition Pore Opening in Primary Cultures of Rat Proximal Tubular Cells

Previous study has demonstrated that mitochondrial-dependent apoptotic pathway is involved in the nephroprotective effect of puerarin (PU) against lead-induced cytotoxicity in primary cultures of rat proximal tubular (rPT) cells. To further clarify how PU exerts its antiapoptotic effects, this study was designed to investigate the role of mitochondrial permeability transition (MPT) and subsequent apoptotic events in the process of PU against Pb-induced cytotoxicity in rPT cells. The results showed that Pb-mediated mitochondrial permeability transition pore (MPTP) opening together with mitochondrial cytochrome c release, activations of caspase-9 and caspase-3, and subsequent poly-ADP-ribose polymerase (PARP) cleavage can be effectively blocked by the addition of PU. Simultaneously, upregulation and downregulation of Bcl-2 and Bax with increased Bcl-2/Bax ratio due to PU administration further alleviated Pb-induced mitochondrial apoptosis. Moreover, PU can reverse Pb-induced ATP depletion by restoring mitochondrial fragmentation to affect ATP production and by regulating expression levels of ANT-1 and ANT-2 to improve ATP transport. In summary, PU produced a significant protection against Pb-induced mitochondrial apoptosis in rPT cells by inhibiting MPTP opening to ameliorate the mitochondrial dysfunction.

The PI3K/AKT/mTOR pathway is a potential predictor of distinct invasive and migratory capacities in human ovarian cancer cell lines

Objectives

To explore the genetic and molecular events that control subclones exhibiting distinct invasive/migratory capacities derived from human epithelial ovarian cancer (EOC) cell line A2780 and SKOV3.

Methods

Single-cell subclones were isolated and established that were derived from the SKOV3 and A2780 cell lines through limiting dilution methodology. Transwell insert assays and MTT assays were performed to screen and identify the subclones exhibiting the highest and the lowest invasive/migratory capacities, and the selected subclones were renamed as A-H (A2780 high), A-L (A2780 low), S-H (SKOV3 high), and S-L (SKOV3 low). Their biological characteristics were evaluated. RNA-Seq was conducted on the targeted subclones.

Results

Compared with their corresponding counterparts, A-H/S-H cells exhibited significantly higher invasive/migratory capacities (P < 0.001 and = 0.001, respectively). A-H/S-H cells displayed a clear reduction in doubling time (P = 0.004 and 0.001, respectively), and a significant increase in the percentage of cells in S phase (P = 0.004 and 0.022, respectively). Additionally, the apoptotic rates of A-H/S-H cells were significantly lower than those of A-L/S-L cells (P = 0.002 and 0.026, respectively). At both mRNA and protein levels, caspase-3 and caspase-7 expression were reduced but Bcl-2 expression was increased in A-H/S-H cells. The TrkB (anoikis-related) and Beclin1 (autophagy-related) levels were consistently high and low, respectively, in both A-H/S-H cells. Resistance to chemotherapy in vitro and higher capacities on tumor formation in vivo was presented in both A-H/S-H cells. PI3K/AKT/mTOR pathway components, PIK3CA, PIK3CD, AKT3, ECM1, GPCR, mTOR and PRKCB were increased but that the Nur77 and PTEN were decreased in A-H/S-H cells, identified by RNA-Seq and consistently confirmed by RT-PCR and Western blot analyses.

Conclusions

Heterogeneous cell subpopulations exhibiting distinct invasive and migratory capacities co-exist within the SKOV3 and A2780 cell lines. PI3K/AKT/mTOR pathway activation is associated with higher invasive and migratory capacities in subpopulations of human ovarian cancer cell lines. Inhibiting this pathway may be useful for the chemoprevention or treatment of EOC.

Preservation of CGRP in myocardium attenuates development of cardiac dysfunction in diabetic rats

BACKGROUND

Calcitonin gene-related peptide (CGRP) plays an important role in cardiovascular regulation, which was found reduced in serum of diabetic patients. To test the hypothesis that lack of CGRP in myocardium is associated with diabetic cardiac dysfunction, which may be improved by preservation of CGRP in diabetic rats.

METHODS AND RESULTS

Diabetes was induced in male Sprague-Dawley rats by streptozotocin (50mg/kg). Two groups of the diabetic rats, one fed with standard laboratory chew and another with the laboratory food plus hot pepper (containing 0.0174% of capsaicin), to stimulate production and release of CGRP. Cardiac functions were evaluated by measurements of intraventricular pressures after 8weeks of development of diabetes. Transient receptor potential vanilloid type 1 (TRPV1), CGRP, β1-adreneregic receptor and norepinephrine were analyzed. Significantly lower levels of TRPV1 and CGRP were detected in the thoracic dorsal root ganglia (DRG) and myocardium of the diabetic animals, along with significant decline in left ventricular systolic pressure (by 24%) and heart rate (by 25%) and increase of the end-diastolic pressure (by 83%) with obvious reduction of CGRP in the DRG, by 41%, the myocardium (by 30%) and the serum (by 20%). The cardiac performance, the TRPV1 and the CGRP in the diabetic animals fed with hot pepper were well preserved. No any significant change in β1-adreneregic receptor and norepinephrine was detected.

CONCLUSION

The findings may suggest a novel mechanism underlying diabetic cardiac dysfunctions via impairing TRPV1-CGRP pathway in myocardium. Preservation of the TRPV1-CGRP mechanism may prevent the development of cardiac dysfunction in diabetes.

Dioscin Induces Apoptosis in Human Cervical Carcinoma HeLa and SiHa Cells through ROS-Mediated DNA Damage and the Mitochondrial Signaling Pathway

Dioscin, a natural product, has activity against glioblastoma multiforme, lung cancer and colon cancer. In this study, the effects of dioscin against human cervical carcinoma HeLa and SiHa cells were further confirmed, and the possible mechanism(s) were investigated. A transmission electron microscopy (TEM) assay and DAPI staining were used to detect the cellular morphology. Flow cytometry was used to assay cell apoptosis, ROS and Ca(2+) levels. Single cell gel electrophoresis and immunofluorescence assays were used to test DNA damage and cytochrome C release. The results showed that dioscin significantly inhibited cell proliferation and caused DNA damage in HeLa and SiHa cells. The mechanistic investigation showed that dioscin caused the release of cytochrome C from mitochondria into the cytosol. In addition, dioscin significantly up-regulated the protein levels of Bak, Bax, Bid, p53, caspase-3, caspase-9, and down-regulated the protein levels of Bcl-2 and Bcl-xl. Our work thus demonstrated that dioscin notably induces apoptosis in HeLa and SiHa cells through adjusting ROS-mediated DNA damage and the mitochondrial signaling pathway.

Potent effects of dioscin against gastric cancer in vitro and in vivo

BACKGROUND

We previously reported the effect of dioscin on human gastric carcinoma SGC-7901 cells, but its effects on other gastric cancers are still unknown.

PURPOSE

The present paper aimed to demonstrate the activity of dioscin against human gastric carcinoma MGC-803 and MKN-45.

STUDY DESIGN

In our study, MGC-803 and MKN-45 cells were used to examine the effects of dioscin on human gastric carcinoma in vitro. The effects of dioscin against human gastric carcinoma in vivo were accomplished by the xenografts of MGC-803 cells in BALB/c nude mice.

METHODS

AO/EB and DAPI staining, TEM, single cell gel electrophoresis and flow cytometry assays were used in cell experiments. Then, an iTRAQ-based proteomics approach, DNA and siRNA transfection experiments were carried out for mechanism investigation.

RESULTS

In MGC-803 cells, dioscin caused DNA damage and mitochondrial change, induced ROS generation, Ca(2+) release and cell apoptosis, and blocked cell cycle at S phase. In vivo results showed that dioscin significantly suppressed the tumor growth of MGC-803 cell xenografts in nude mice. In addition, dioscin markedly inhibited cell migration, caused Cytochrome c release and adjusted mitochondrial signal pathway. Then, an iTRAQ-based proteomics approach was carried out and 121 differentially expressed proteins were found, in which five biomarkers associated with cell cycle, apoptosis and migration were evaluated. Dioscin significantly up-regulated the levels of GALR-2 and RBM-3, and down-regulated CAP-1, Tribbles-2 and CliC-3. Furthermore, overexpressed DNA transfection of CAP-1 enhanced cell migration and invasion, which was decreased by dioscin. SiRNA to Tribbles-2 affected the protein levels of Bcl-2, Bax and MAPKs, suggesting that dioscin decreased Tribbles-2 level leading to cell apoptosis.

CONCLUSION

Our works confirmed the activity of dioscin against gastric cancer. In addition, this work also provided that dioscin is a new potent candidate for treating gastric cancer in the future.

The Mitochondrial Permeability Transition Pore: Channel Formation by F-ATP Synthase, Integration in Signal Transduction, and Role in Pathophysiology

The mitochondrial permeability transition (PT) is a permeability increase of the inner mitochondrial membrane mediated by a channel, the permeability transition pore (PTP). After a brief historical introduction, we cover the key regulatory features of the PTP and provide a critical assessment of putative protein components that have been tested by genetic analysis. The discovery that under conditions of oxidative stress the F-ATP synthases of mammals, yeast, and Drosophila can be turned into Ca(2+)-dependent channels, whose electrophysiological properties match those of the corresponding PTPs, opens new perspectives to the field. We discuss structural and functional features of F-ATP synthases that may provide clues to its transition from an energy-conserving into an energy-dissipating device as well as recent advances on signal transduction to the PTP and on its role in cellular pathophysiology.

Regulated necrotic cell death: the passive aggressive side of Bax and Bak

Although the molecular effectors of apoptotic cell death have been largely annotated over the past 30 years, leading to a strong biological understanding of this process and its importance in cell biology, cell death through necrosis has only recently been accepted as a similarly regulated process with definable molecular effectors. The mitochondria are important and central mediators of both apoptosis and regulated necrosis. In apoptosis, the B-cell leukemia/lymphoma 2 (Bcl-2) family members Bcl-2-associated protein x (Bax) and Bcl-2 homologues antagonist/killer (Bak) undergo oligomerization in the outer mitochondrial membrane resulting in the release of apoptosis inducing substrates and the activation of caspases and nucleases. In contrast, during necrosis the mitochondria become dysfunctional and maladaptive in conjunction with reactive oxygen species production and the loss of ATP production, in part through opening of the mitochondrial permeability transition pore. Although regulated necrosis is caspase-independent, recent evidence has shown that it still requires the apoptotic regulators Bax/Bak, which can regulate the permeability characteristics of the outer mitochondrial membrane in their nonoligomerized state. Here, we review the nonapoptotic side of Bcl-2 family, specifically the role of Bax/Bak in regulated necrotic cell death. We will also discuss how these Bcl-2 family member effectors could be part of a larger integrated network that ultimately decides the fate of a given cell somewhere within a molecular continuum between apoptosis and regulated necrosis.

Melatonin attenuates the mitochondrial translocation of mitochondrial fission proteins and Bax, cytosolic calcium overload and cell death in methamphetamine-induced toxicity in neuroblastoma SH-SY5Y cells

Methamphetamine (METH) is an addictive drug that can cause toxicity and degeneration in the brain. Several pieces of evidence have demonstrated that METH toxicity results in increases in oxidative stress that regulate an intracellular signaling cascade that leads to cell death. Recently, several studies have emphasized that the overload of cytosolic calcium levels and mitochondrial fission into a small mitochondrial structure is involved in cell death processes. In the present study, we aimed to investigate the effects of METH toxicity on cytosolic calcium overload and mitochondrial fission in neuroblastoma SH-SY5Y cells. Additionally, the protective effect of melatonin against METH-induced toxicity was also investigated. The results of the present study demonstrated that METH significantly decreases cell viability and increases the levels of mitochondrial fission (Fis1 and Drp1) proteins and pro-apoptotic protein, Bax in isolated mitochondria. The levels of Drp1 in the cytosol of METH-treated cells had no significant differences compared to the control untreated cells. METH also significantly increased the cytosolic calcium levels. Melatonin reversed the toxic effects of METH by restoring cell viability and inhibiting the increase in mitochondrial Fis1 levels and the mitochondrial translocation of Drp1 and Bax. Additionally, melatonin was able to reduce the METH-induced increase in cytosolic calcium levels and fragmented mitochondria into small globular structures in SH-SY5Y cells. The results of the present study demonstrate the potential abilities of melatonin to maintain the homeostasis of mitochondrial dynamics and cytosolic calcium levels in METH-induced toxicity in neuronal cells.

Molecular mechanisms of cell death: central implication of ATP synthase in mitochondrial permeability transition

The term mitochondrial permeability transition (MPT) is commonly used to indicate an abrupt increase in the permeability of the inner mitochondrial membrane to low molecular weight solutes. Widespread MPT has catastrophic consequences for the cell, de facto marking the boundary between cellular life and death. MPT results indeed in the structural and functional collapse of mitochondria, an event that commits cells to suicide via regulated necrosis or apoptosis. MPT has a central role in the etiology of both acute and chronic diseases characterized by the loss of post-mitotic cells. Moreover, cancer cells are often relatively insensitive to the induction of MPT, underlying their increased resistance to potentially lethal cues. Thus, intense efforts have been dedicated not only at the understanding of MPT in mechanistic terms, but also at the development of pharmacological MPT modulators. In this setting, multiple mitochondrial and extramitochondrial proteins have been suspected to critically regulate the MPT. So far, however, only peptidylprolyl isomerase F (best known as cyclophilin D) appears to constitute a key component of the so-called permeability transition pore complex (PTPC), the supramolecular entity that is believed to mediate MPT. Here, after reviewing the structural and functional features of the PTPC, we summarize recent findings suggesting that another of its core components is represented by the c subunit of mitochondrial ATP synthase.

Cancer-type-specific crosstalk between autophagy, necroptosis and apoptosis as a pharmacological target

Cell death plays an essential role in the development of organs, homeostasis, and cancer. Apoptosis and programmed necrosis are two major types of cell death, characterized by different cell morphology and pathways. Accumulating evidence shows autophagy as a new alternative target to treat tumor resistance. Besides its well-known pro-survival role, autophagy can be a physiological cell death process linking apoptosis and programmed necrosis cell death pathways, by various molecular mediators. Here, we summarize the effects of pharmacologically active compounds as modulators of different types of cancer cell death depending on the cellular context. Indeed, current findings show that both natural and synthetic compounds regulate the interplay between apoptosis, autophagy and necroptosis stimulating common molecular mediators and sharing common organelles. In response to specific stimuli, the same death signal can cause cells to switch from one cell death modality to another depending on the cellular setting. The discovery of important interconnections between the different cell death mediators and signaling pathways, regulated by pharmacologically active compounds, presents novel opportunities for the targeted treatment of cancer. The aim of this review is to highlight the potential role of these compounds for context-specific anticancer therapy.

Lipid analogues as potential drugs for the regulation of mitochondrial cell death

The mitochondrion plays an important role in the production of energy as ATP, the regulation of cell viability and apoptosis, and the biosynthesis of major structural and regulatory molecules, such as lipids. During ATP production, reactive oxygen species are generated that alter the intracellular redox state and activate apoptosis. Mitochondrial dysfunction is a well-recognized component of the pathogenesis of diseases such as cancer. Understanding mitochondrial function, and how this is dysregulated in disease, offers the opportunity for the development of drug molecules to specifically target such defects. Altered energy metabolism in cancer, in which ATP production occurs largely by glycolysis, rather than by oxidative phosphorylation, is attributable in part to the up-regulation of cell survival signalling cascades. These pathways also regulate the balance between pro- and anti-apoptotic factors that may determine the rate of cell death and proliferation. A number of anti-cancer drugs have been developed that target these factors and one of the most promising groups of agents in this regard are the lipid-based molecules that act directly or indirectly at the mitochondrion. These molecules have emerged in part from an understanding of the mitochondrial actions of naturally occurring fatty acids. Some of these agents have already entered clinical trials because they specifically target known mitochondrial defects in the cancer cell.

The mitochondrial permeability transition pore and cancer: molecular mechanisms involved in cell death

Since its discovery in the 1970s, the mitochondrial permeability transition (MPT) has been proposed to be a strategic regulator of cell death. Intense research efforts have focused on elucidating the molecular components of the MPT because this knowledge may help to better understand and treat various pathologies ranging from neurodegenerative and cardiac diseases to cancer. In the case of cancer, several studies have revealed alterations in the activity of the mitochondrial permeability transition pore (mPTP) and have determined its regulatory mechanism; these studies have also suggested that suppression of the activity of the mPTP, rather than its inactivation, commonly occurs in solid neoplasms. This review focuses on the most recent advances in understanding mPTP regulation in cancer and highlights the ability of the mPTP to impede the mechanisms of cell death.