Role of mitochondrial membrane permeabilization in apoptosis and cancer

Cerium oxide nanoparticles: Chemical properties, biological effects and potential therapeutic opportunities (Review)

The chemistry of pure cerium oxide (CeO2-x) nanoparticles has been widely studied since the 1970s, especially for chemical catalysis. CeO2-x nanoparticles have been included in an important class of industrial metal oxide nanoparticles and have been attributed a range of wide applications, such as ultraviolet absorbers, gas sensors, polishing agents, cosmetics, consumer products, high-tech devices and fuel cell conductors. Despite these early applications in the field of chemistry, the biological effects of CeO2-x nanoparticles were only explored in the 2000s. Since then, CeO2-x nanoparticles have gained a spot in research related to various diseases, especially the ones in which oxidative stress plays a part. Due to an innate oxidation state variation on their surface, CeO2-x nanoparticles have exhibited redox activities in diseases, such as cancer, acting either as an oxidizing agent, or as an antioxidant. In biological models, CeO2-x nanoparticles have been shown to modulate cancer cell viability and, more recently, cell death pathways. However, a deeper understanding on how the chemical structure of CeO2-x nanoparticles (including nanoparticle size, shape, suspension, agglomeration in the medium used, pH of the medium, type of synthesis and crystallite size) influences the cellular effects observed remains to be elucidated. In the present review, the chemistry of CeO2-x nanoparticles and their impact on biological models and modulation of cell signalling, particularly focusing on oxidative and cell death pathways, were investigated. The deeper understanding of the chemical activity of CeO2-x nanoparticles may provide the rationale for further biomedical applications towards disease treatment and drug delivery purposes.

Blue light photobiomodulation induced apoptosis by increasing ROS level and regulating SOCS3 and PTEN/PI3K/AKT pathway in osteosarcoma cells

Blue light photobiomodulation (PBM) has attracted great attention in diminishing proliferation and inducing death of cancer cells recently. Osteosarcoma (OS) primarily occurring in children and adolescents, the limitations of drug resistance and limb salvage make it urgent to develop and identify new adjuvant therapeutic strategies. In this work, we attempted to research the anticancer effects and biological mechanisms of blue light PBM in human OS MG63 cells. The effects of various blue light parameters on MG63 cells indicated that suppressed cell proliferation and cell migration, induced cell apoptosis which are experimentally assessed using multiple assays including CCK, LDH, wound healing assay and Hoechst staining. Concurrently, the increases of ROS level and the inhibition of PI3K and AKT expression were identified under high-dose blue light PBM in MG63 cells. Meanwhile, SOCS3 is a major inducible anti-tumor molecule, we also found that blue light LED substantially promoted its expression. Thus, this study proposed that bule light PBM may be a hopeful therapeutic approach in OS clinical treatment in the future.

In Response to Precision Medicine: Current Subcellular Targeting Strategies for Cancer Therapy

Emerging as a potent anticancer treatment, subcellular targeted cancer therapy has drawn increasing attention, bringing great opportunities for clinical application. Here, two targeting strategies for four main subcellular organelles (mitochondria, lysosome, endoplasmic reticulum, and nucleus), including molecule- and nanomaterial (inorganic nanoparticles, micelles, organic polymers, and others)-based targeted delivery or therapeutic strategies, are summarized. Phototherapy, chemotherapy, radiotherapy, immunotherapy, and "all-in-one" combination therapy are among the strategies covered in detail. Such materials are constructed based on the specific properties and relevant mechanisms of organelles, enabling the elimination of tumors by inducing dysfunction in the corresponding organelles or destroying specific structures. The challenges faced by organelle-targeting cancer therapies are also summarized. Looking forward, a paradigm for organelle-targeting therapy with enhanced therapeutic efficacy compared to current clinical approaches is envisioned.

Evaluation Expression of the Caspase-3 and Caspase-9 Apoptotic Genes in Schizophrenia Patients

Objective

Apoptosis is programmed cell death that occurs by several pathways. Caspase-3 is induced by active caspase-9 via the intrinsic pathway. The aim of this research was to explore the expression of caspase-3 and caspase-9 in schizophrenia patients and healthy samples.

Methods

RNA was isolated from the peripheral blood of 39 schizophrenia patients' and healthy samples. After cDNA synthesis, real time PCR (RT-PCR) was used to analyse caspase-3 and caspase-9 gene expression. The severity of psychopathological symptoms of schizophrenia was evaluated using the Positive and Negative Symptoms Scale for schizophrenia (PANSS) and Clinical Global Impressions (CGI).

Results

The expression of caspase-3 and caspase-9 genes was higher in schizophrenia patients than in healthy samples (p = 0.012, p = 0.002, respectively). The increase in caspase-3 gene expression was significant with being male, smoking and with a duration of less than 6 years (p = 0.047, p = 0.049, p = 0.034, respectively). On the other hand, the increase in caspase-9 gene expression was significant in patients who is smoke, have children, and are under 33 years old (p = 0.040, p = 0.043, p = 0.045, respectively). A significant positive correlation was detected between the caspase-3 and caspase-9 gene expression (r = 0.3218, p = 0.049).

Conclusion

Our findings indicate that caspase-3 and caspase-9 gene expression may activate cell death mechanisms by intrinsic apoptotic genes. Furthermore, caspase-3 and caspase-9 may play essential roles in different ways in schizophrenia. Hence there is a need to further study the apoptotic mechanism with expanded patient populations.

The Pt(S-pr-thiosal)2 and BCL1 Leukemia Lymphoma: Antitumor Activity In Vitro and In Vivo

B cell malignancies are, despite the development of targeted therapy in a certain percentage of the patients still a chronic disease with relapses, requiring multiple lines of therapy. Regimens that include platinum-based drugs provide high response rates in different B cell lymphomas, high-risk chronic lymphocytic leukemia (CLL), and devastating complication of CLL, Richter’s syndrome. The aim of this study was to explore the potential antitumor activity of previously synthetized platinum(IV) complex with alkyl derivatives of thyosalicilc acid, PtCl2(S-pr-thiosal)2, toward murine BCL1 cells and to delineate possible mechanisms of action. The PtCl2(S-pr-thiosal)2 reduced the viability of BCL1 cells in vitro but also reduced the growth of metastases in the leukemia lymphoma model in BALB/c mice. PtCl2(S-pr-thiosal)2 induced apoptosis, inhibited proliferation of BCL1 cells, and induced cell cycle disturbance. Treatment of BCL1 cells with PtCl2(S-pr-thiosal)2 inhibited expression of cyclin D3 and cyclin E and enhanced expression of cyclin-dependent kinase inhibitors p16, p21, and p27 resulting in cell cycle arrest in the G1 phase, reduced the percentage of BCL1 cells in the S phase, and decreased expression of Ki-67. PtCl2(S-pr-thiosal)2 treatment reduced expression of phosphorylated STAT3 and downstream-regulated molecules associated with cancer stemness and proliferation, NANOG, cyclin D3, and c-Myc, and expression of phosphorylated NFκB in vitro and in vivo. In conclusion, PtCl2(S-pr-thiosal)2 reduces STAT3 and NFκB phosphorylation resulting in inhibition of BCL1 cell proliferation and the triggering of apoptotic cell death.

1,4-Naphthoquinone (CNN1) Induces Apoptosis through DNA Damage and Promotes Upregulation of H2AFX in Leukemia Multidrug Resistant Cell Line

The multidrug resistance (MDR) phenotype is one of the major obstacles in the treatment of chronic myeloid leukemia (CML) in advantage stages such as blast crisis. In this scenario, more patients develop resistance mechanisms during the course of the disease, making tyrosine kinase inhibitors (TKIs) target therapies ineffective. Therefore, the aim of the study was to examine the pharmacological role of CNN1, a para-naphthoquinone, in a leukemia multidrug resistant cell line. First, the in vitro cytotoxic activity of Imatinib Mesylate (IM) in K-562 and FEPS cell lines was evaluated. Subsequently, membrane integrity and mitochondrial membrane potential assays were performed to assess the cytotoxic effects of CNN1 in K-562 and FEPS cell lines, followed by cell cycle, alkaline comet assay and annexin V-Alexa Fluor® 488/propidium iodide assays (Annexin/PI) using flow cytometry. RT-qPCR was used to evaluate the H2AFX gene expression. The results demonstrate that CNN1 was able to induce apoptosis, cell membrane rupture and mitochondrial membrane depolarization in leukemia cell lines. In addition, CNN1 also induced genotoxic effects and caused DNA fragmentation, cell cycle arrest at the G2/M phase in leukemia cells. No genotoxicity was observed on peripheral blood mononuclear cells (PBMC). Additionally, CNN1 increased mRNA levels of H2AFX. Therefore, CNN1 presented anticancer properties against leukemia multidrug resistant cell line being a potential anticancer agent for the treatment of resistant CML.

Usnic acid induced changes in biomolecules and their association with apoptosis in squamous carcinoma (A-431) cells: A flow cytometry, FTIR and DLS spectroscopic study

Many natural products induce apoptotic cell death in cancer cells, though studies on their interactions with macromolecules are limited. For the first time, this study demonstrated the cytotoxic potential of usnic acid (UA) against squamous carcinoma (A-431) cells and the associated changes in cell surface proteins, lipids and DNA by attenuated total reflection- fourier transform infrared spectroscopy (ATR-FTIR) and dynamic light scattering (DLS) spectroscopic studies. The IC₅₀ for UA was 98.9 µM after treatment of A-431 cells for 48 h, while the IC₅₀ reduced to 39.2 µM after 72 h of incubation time. UA induced oxidative stress in treated cells as confirmed by DCFHDA flow cytometry assay, depletion in reduced glutathione and increase in lipid peroxidation. The oxidative stress resulted in conformation change in amide I, amide II protein bands and DNA as observed by ATR-FTIR in UA treated A-431 cells. Shift in secondary structures of proteins from α helix to β sheets and structural changes in DNA was observed in UA treated A-431 cells. An increase in the band intensity of phospholipids, increased distribution of lipid and change in membrane potential was noted in UA treated cells, which was confirmed by externalization of phosphatidylserine to the outer membrane by annexin V-FITC/PI assay. Increase in mitochondrial membrane potential, cell cycle arrest at G0/G1 phase by flow cytometry and activation of caspase-3/7 dependent proteins confirmed the UA induced apoptosis in treated A-431 cells. FTIR and DLS spectroscopy confirmed the changes in biomolecules after UA treatment, which were associated with apoptosis, as observed by flow cytometry.

Probing the Link between Pancratistatin and Mitochondrial Apoptosis through Changes in the Membrane Dynamics on the Nanoscale

Pancratistatin (PST) is a natural antiviral alkaloid that has demonstrated specificity toward cancerous cells and explicitly targets the mitochondria. PST initiates apoptosis while leaving healthy, noncancerous cells unscathed. However, the manner by which PST induces apoptosis remains elusive and impedes the advancement of PST as a natural anticancer therapeutic agent. Herein, we use neutron spin-echo (NSE) spectroscopy, molecular dynamics (MD) simulations, and supporting small angle scattering techniques to study PST's effect on membrane dynamics using biologically representative model membranes. Our data suggests that PST stiffens the inner mitochondrial membrane (IMM) by being preferentially associated with cardiolipin, which would lead to the relocation and release of cytochrome c. Second, PST has an ordering effect on the lipids and disrupts their distribution within the IMM, which would interfere with the maintenance and functionality of the active forms of proteins in the electron transport chain. These previously unreported findings implicate PST's effect on mitochondrial apoptosis.

Roles of calpain in the apoptosis of Eimeria tenella host cells at the middle and late developmental stages

This study investigated the role of calpain in Eimeria tenella-induced host cell apoptosis. Chick embryo cecal epithelial cell culture technology, flow cytometry, enzyme-linked immunosorbent assays, and fluorescence quantitative PCR were used to detect the E. tenella host cell apoptotic rate, Bax and Bid expression levels, and calpain activity. The results demonstrated that Bax, Bid, and calpain levels were upregulated and apoptosis was increased following E. tenella infection at 24-120 h. Calpain levels were reduced by pharmacological inhibition of calpain using SJA6017 or by blocking Ca²⁺ entry into the cell using BAPTA/AM at 24-120 h. The mRNA and protein levels of Bax and Bid, the E. tenella infection rate, and the early apoptotic and late apoptotic (necrosis) rates were decreased by using SJA6017 at 24-120 h. These results indicated that E. tenella-promoted host cell apoptosis is regulated by calpain via Bid and Bax at 24-120 h. Thus, manipulation of calpain levels could be used to manage E. tenella infection in chickens in the middle and late developmental stages.

GPR17 signaling activation by CHBC agonist induced cell death via modulation of MAPK pathway in glioblastoma

AIM

Glioblastoma multiforme (GBM) is the most common and aggressive primary adult brain tumor. GBM is characterized by a heterogeneous population of cells that are resistant to chemotherapy. Recently, we have synthesized CHBC, a novel indole derivative targeted to GBM biomarker G-protein-coupled receptor 17 and inhibitor of GBM cells. In this study, CHBC was further investigated to characterize the efficiency of this agonist at the molecular level and its underlying mechanism in GBM cell death induction.

MATERIALS AND METHODS

The effect of CHBC and TMZ was determined using time dependent inhibitor assay in glioblastoma cells, LN229 and SNB19. Drug induced cell cycle arrest was measured using PI staining followed by image analysis. The induction of apoptosis and mechanism of action of CHBC was studied using apoptosis, caspase 3/7 and mitochondrial membrane permeability assays. Modulation of the key genes involved in MAPK signaling pathway was also measured using immunoblotting array.

KEY FINDINGS

The inhibitory kinetic study has revealed that CHBC inhibited SNB19 and LN229 cell growth in a time-dependent manner. Furthermore, CHBC with the IC50 of 85 μM, mediated cell death through an apoptosis mechanism in both studied cell lines. The study also has revealed that CHBC targets GPR17 leading to the induction of apoptosis via the activation of Caspase 3/7 and dysfunction of mitochondrial membrane potential. In addition, CHBC treatment led to marked G2/M cell cycle arrest. The protein array has confirmed the anticancer effect of CHBC by the disruption of the mitogen-activated protein kinase pathway (MAPK).

SIGNIFICANCE

Taken together, these results demonstrated that CHBC induced G2/M cell cycle arrest and apoptosis by disrupting MAPK signaling in human glioblastoma cells. This study concludes that CHBC represent a class of compounds for treating glioblastoma.

Palmitate Enhances the Efficacy of Cisplatin and Doxorubicin against Human Endometrial Carcinoma Cells

Endometrial cancer is the most common gynecological cancer worldwide. At present there is no effective screening test for its early detection and no curative treatment for women with advanced-stage or recurrent disease. Overexpression of fatty acid synthase is a common molecular feature of a subgroup of sex steroid-related cancers associated with poor prognoses, including endometrial cancers. Disruption of this fatty acid synthesis leads to cell apoptosis, making it a potential therapeutic target. The saturated fatty acid palmitate reportedly induces lipotoxicity and cell death by inducing oxidative stress in many cell types. Here, we explored the effects of palmitate combined with doxorubicin or cisplatin in the HEC-1-A and RL95-2 human endometrial cancer cell lines. The results showed that physiological concentrations of exogenous palmitate significantly increased cell cycle arrest, DNA damage, autophagy, and apoptosis in both RL95-2 and HEC-1-A cells. It also increased the chemosensitivity of both cell types. Notably, we did not observe that palmitate lipotoxicity reflected increased levels of reactive oxygen species, suggesting palmitate acts via a different mechanism in endometrial cancer. This study thus provides a potential therapeutic strategy in which palmitate is used as an adjuvant in the treatment of endometrial cancer.

Membrane-Activated Fluorescent Probe for High-Fidelity Imaging of Mitochondrial Membrane Potential

Mitochondrial membrane potential (ΔΨ_m) is a key indicator of cell health or injury due to its vital roles in adenosine 5'-triphosphate synthesis. Thus, monitoring ΔΨ_m is of great significance for the assessment of cell status, diagnosis of diseases, and medicament screening. Cationic fluorescent probes suffer from severe photobleaching or false positive signals due to the luminescence of the probe on non-mitochondria. Herein, we report a lipophilic cationic fluorescent probe [1-methyl-2-(4-(1,2,2-triphenylvinyl)styryl)-β-naphthothiazol-1-ium trifluoromethanesulfonate (TPE-NT)] with the features of aggregation-induced emission and intramolecular charge transfer for imaging ΔΨ_m in live cells. TPE-NT is enriched on the surface of the mitochondrial inner membrane due to the negative ΔΨ_m, and its fluorescence is activated in the high-viscosity microenvironment. The false positive signals of emission from TPE-NT on non-mitochondria are therefore effectively eliminated. Moreover, TPE-NT exhibits a Stokes shift of >200 nm, near-infrared (∼675 nm) emission, excellent photostability, and low cytotoxicity, which facilitate real-time imaging in live cells. Cell imaging confirmed that the probe can rapidly and reliably report mitochondrial depolarization (decrement of ΔΨ_m) during cell damage caused by CCCP and H₂O₂ as well as mitochondrial polarization (increment of ΔΨ_m) by oligomycin. Furthermore, the probe successfully detected the reduction of ΔΨ_m in these cell models of hypoxia, heat damage, acidification, aging, inflammation, mitophagy, and apoptosis caused by hypoxia, heatstroke, lactate/pyruvate, doxorubicin, lipopolysaccharide, rapamycin, monensin, and nystatin, respectively.

Epigenetic Deregulation of Apoptosis in Cancers

Cancer cells possess the ability to evade apoptosis. Genetic alterations through mutations in key genes of the apoptotic signaling pathway represent a major adaptive mechanism of apoptosis evasion. In parallel, epigenetic changes via aberrant modifications of DNA and histones to regulate the expression of pro- and antiapoptotic signal mediators represent a major complementary mechanism in apoptosis regulation and therapy response. Most epigenetic changes are governed by the activity of chromatin modifying enzymes that add, remove, or recognize different marks on histones and DNA. Here, we discuss how apoptosis signaling components are deregulated at epigenetic levels, particularly focusing on the roles of chromatin-modifying enzymes in this process. We also review the advances in cancer therapies with epigenetic drugs such as DNMT, HMT, HDAC, and BET inhibitors, as well as their effects on apoptosis modulation in cancer cells. Rewiring the epigenome by drug interventions can provide therapeutic advantage for various cancers by reverting therapy resistance and leading cancer cells to undergo apoptotic cell death.

Cell death modulation by transient receptor potential melastatin channels TRPM2 and TRPM7 and their underlying molecular mechanisms

Transient receptor potential melastatin (TRPM) channels are members of the transient receptor potential (TRP) channels, a family of evolutionarily conserved integral membrane proteins. TRPM channels are nonselective cation channels, mediating the influx of various ions including Ca²⁺, Na⁺ and Zn²⁺. The function of TRPM channels is vital for cell proliferation, cell development and cell death. Cell death is a key procedure during embryonic development, organism homeostasis, aging and disease. The category of cell death modalities, beyond the traditionally defined concepts of necrosis, autophagy, and apoptosis, were extended with the discovery of pyroptosis, necroptosis and ferroptosis. As upstream signaling regulators of cell death, TRPM channels have been involved inrelevant pathologies. In this review, we introduced several cell death modalities, then summarized the contribution of TRPM channels (especially TRPM2 and TRPM7) to different cell death modalities and discussed the underlying regulatory mechanisms. Our work highlighted the possibility of TRPM channels as potential therapeutic targets in cell death-related diseases.

Physical confinement during cancer cell migration triggers therapeutic resistance and cancer stem cell-like behavior

Metastasized cancer cells have an increased resistance to therapies leading to a drastic decrease in patient survival rates. However, our understanding of the cause for this enhanced resistance is lacking. In this study, we report that physically tight confinement during cancer cell migration triggers therapeutic resistance and induces cancer stem cell-like behavior including up-regulation in efflux proteins and in cancer stem cell related markers. Moreover, the re-localization of Yes-associated protein (YAP) to the cell nucleus indicated an elevated level of cytoskeletal tension. The increased cytoskeletal tension suggested that mechanical interactions between cancer cells and tight surroundings during metastasis is one of the factors that contributes to therapeutic resistance and acquisition of cancer stem cell (CSC) like features. With this system and supporting data, we are able to study cells with therapeutic resistance and CSC-like properties for the future purpose of developing new strategies for the treatment of metastatic cancer.

Mechanism of deoxynivalenol mediated gastrointestinal toxicity: Insights from mitochondrial dysfunction

Deoxynivalenol (DON) is a mycotoxin predominantly produced by Fusarium genus, and widely contaminates cereals and associated products all over the world. The intestinal toxicity of DON is well established. However, intestinal homeostasis involves mitochondria, which has rarely been considered in the context of DON exposure. We summarize the recent knowledge on mitochondria as a key player in maintaining intestinal homeostasis based on their functions in cellular energy metabolism, redox homeostasis, apoptosis, intestinal immune responses, and orchestrated bidirectional cross-talk with gut microbe. In addition, we discuss the pivotal roles of mitochondrial dysfunction in the intestinal toxicity of DON and highlight promising mitochondrial-targeted therapeutics for DON-induced intestinal injury. Recent studies support that the intestinal toxicity of DON is attributed to mitochondrial dysfunction as a critical factor. Mitochondrial dysfunction characterized by failure in respiratory capacities and ROS overproduction has been demonstrated in intestinal cells exposed to DON. Perturbation of mitochondrial respiration leading to ROS accumulation is implicated in the early initiation of apoptosis. DON-induced intestinal inflammatory response is tightly linked to the mitochondrial ROS, whereas immunosuppression is intimately associated with mitophagy inhibition. DON perturbs the orchestrated bidirectional cross-talk between gut microbe and host mitochondria, which may be involved in DON-induced intestinal toxicity.

Ameliorative Effect of Ananas comosus on Cobalt Chloride-Induced Hypoxia in Caco2 cells via HIF-1α, GLUT 1, VEGF, ANG and FGF

In the present study, protective effects of Ananas comosus i.e., pineapple pulp (PA) against cobalt chloride (CoCl₂)‑induced hypoxia in Caco-2 cells were evaluated. PA reduces levels of lipid peroxidation, reactive oxygen and nitrogen species. It was proved to be cytoprotective and increased anti-oxidant activity against CoCl₂-induced hypoxia. The inference drawn from this experiment was CoCl₂-induced hypoxia that regulates hypoxia-inducible factor-1 (HIF-1), a transcription factor. It was also confirmed that PA pre-treatment inhibited the expression of HIF-1α, thereby downregulating the hypoxia-associated gene/protein expressions such as GLUT-1, VEGF, ANG and FGF. Finally, supplementation of PA could help in snow-balling the digestive hormones like leptin and CCK in hypoxic conditions. Therefore, this report provides substantial proof of reducing the hypoxia-induced loss of appetite at high-altitude environments. Graphical Abstract.

Sequential receptor-mediated mixed-charge nanomedicine to target pancreatic cancer, inducing immunogenic cell death and reshaping the tumor microenvironment

Pancreatic cancer (PC) is an aggressive form of cancer with dense stroma and immune-suppressive microenvironment, which are the major barriers for treatment. To address such barriers, this study aimed to develop a sequential receptor-mediated mixed-charge targeted delivery system for PC based on 2-(3-((S)-5-amino-1-carboxypentyl)-ureido) pentanedioate (ACUPA^-) and triphenylphosphonium (TPP⁺) modified nanomicelles containing ingenol-3-mebutate (I3A), which was named ACUPA^-/TPP⁺-I3A or ACUPA/TPP-I3A. ACUPA/TPP-I3A induced immunogenic cell death (ICD), which significantly increased the number of tumor-infiltrating T lymphocytes, activated adaptive immunity, and achieved superior survival time. I3A, a novel anticancer drug, could induce PC cell necrosis to release damage-associated molecular patterns, thereby activating adaptive immunity. With certain ratios of negatively (ACUPA^-) and positively (TPP⁺) charged ligands, ACUPA/TPP-I3A acquired a negative charge in plasma (pH 7.4, to inhibit aggregation and uptake in the circulation) and was neutral in the acidic tumor microenvironment (pH 5.0-6.0, to overcome electrostatic hindrances and facilitate transcytosis). Furthermore, neovascular endothelium-specific ACUPA enabled rapid transcytosis of ACUPA/TPP-I3A across tumor vessel walls, entering into endosome/lysosomes (pH 4.5-5.0, its charge became positive and exhibited lysosome escape). Then, ACUPA/TPP-I3A selectively targeted mitochondria, which correlated with TPP-mediated effect. Finally, I3A was released to induce ICD that activated adaptive immunity and achieved superior survival time. Therefore, reshaping of the tumor microenvironment and potentiating antitumor immunity using ACUPA^-/TPP⁺-I3A constituted a novel strategy to prolong the survival time.

Detection and monitoring of the neuroprotective behavior of curcumin micelles based on an AIEgen probe

In recent years, the role of mitochondrial injury in the pathogenesis of Alzheimer's disease (AD) has attracted extensive attention. Studies have shown that curcumin (Cur) can protect nerve cells from beta-amyloid (Aβ)-induced mitochondrial damage. However, natural Cur encounters limited application due to its poor biocompatibility and bioavailability. To improve the solubility and biocompatibility of natural Cur, we prepared water-soluble curcumin micelles (CurM). Furthermore, the mitochondria-specific aggregation-induced emission (AIE) probe (TPE-Ph-In) was employed to observe the protective effect of CurM on the damage of mitochondrial morphology, distribution, and membrane potential caused by Aβ. Results showed that CurM had higher solubility, stronger stability and retention effect, and better cellular uptake than that of natural Cur. Furthermore, the inhibitory effects of CurM on mitochondrial morphology, distribution, and membrane potential damage induced by Aβ25-35 were observed utilizing TPE-Ph-In as an indicator of mitochondrial morphology and membrane potential. Thus, this method provides a useful strategy for experimental research and clinical treatment of AD with mitochondrial damage as the pathogenic mechanism.

The role of melatonin in sarcopenia: Advances and application prospects

Sarcopenia is an age-related disease that has gradually become a serious health problem for elderly individuals. It not only greatly increases the risk of falls, weakness, and disability but also reduces the ability of patients to take care of themselves. Sarcopenia can directly affect the quality of life and disease prognosis of elderly individuals. However, drug interventions for this disease are lacking. Melatonin is a biological hormone produced by the body that has good free radical scavenging effects, antioxidant effects and other effects. It was originally used as a sleep aid and is now being used for an increasing number of new indications. Its effect on sarcopenia has also begun to attract attention. It is currently known that it can protect the mitochondria of skeletal muscle cells, maintain the number of muscle fibres, partially reverse the pathological changes of ageing muscle tissue, and increase muscle strength in patients with sarcopenia. A large number of microRNAs are expressed during cell ageing, that in turn provides a biological background to age-related diseases, like sarcopenia. Increasing studies have found an interaction between melatonin and miRNAs, suggesting that melatonin can be used in the treatment of sarcopenia. The increased expression of inflammation-associated miRNA-483 in elderly patients may be the basis for the age-dependent decrease in melatonin secretion，that may play a role in the morbidity of sarcopenia. Melatonin is closely related to sarcopenia. It has a wide range of effects on sarcopenia and has good application prospects for the prevention and treatment of sarcopenia.

Induction of apoptosis by Shikonin through ROS-mediated intrinsic and extrinsic apoptotic pathways in primary effusion lymphoma

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Shikonin (SHK) induced apoptosis in Primary effusion lymphoma (PEL).

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SHK treatment rabidly generated ROS and activated JNK and p38.

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SHK inhibited ascites formation in xenograft mice.

Primary effusion lymphoma (PEL) is an incurable non-Hodgkin's lymphoma and novel biology-based treatments are urgently needed in clinical settings. Shikonin (SHK), a napthoquinone derivative, has been used for the treatment of solid tumors. Here, we report that SHK is an effective agent for the treatment of PEL. Treatment with SHK results in significant reduction of proliferation in PEL cells and their rapid apoptosis in vitro. SHK-induced apoptosis of PEL cells is accompanied by the generation of reactive oxygen species (ROS), loss of mitochondrial membrane potential (Δψm), an activation of c-Jun-N-terminal kinase (JNK), p38, as well as caspase-3, -8, and -9. Scavenging of ROS in the presence of N-acetylcysteine (NAC) almost blocks the loss of mitochondrial membrane Δψm, activation of JNK, cleavage of caspase-3, -9, and an induction of apoptosis in SHK treated PEL cells. SP600125, a specific inhibitor of JNK, also rescues a proportion of cells from the apoptotic effect of SHK. In addition, inhibition of caspase activation in the presence of pan-caspase inhibitor, Q-VD-OPh, blocks the SHK-inducing apoptosis, but doesn't completely inhibit SHK-mediated JNK activation. Therefore, ROS is an upstream trigger of SHK-induced caspase dependent apoptosis of PEL cells through disruption of mitochondrial membrane Δψm in an intrinsic pathway and an activation of JNK in an extrinsic pathway. In a PEL xenografted mouse model, SHK treatment suppresses PEL-mediated ascites formation without showing any significant adverse toxicity. These results suggested that SHK could be a potent anti-tumor agent for the treatment of PEL.

Mechanisms Underlying Development of Taurine-Deficient Cardiomyopathy

Taurine is a ubiquitous β-amino acid that plays an essential role in ensuring normal mitochondrial and myocardial function. In the mitochondria, taurine reacts with a tRNA forming a 5-taurinomethyluridine conjugate that primarily regulates the biosynthesis of the mitochondria encoded protein, ND6, which serves as a subunit of complex I of the respiratory chain. Impaired formation of the taurine conjugate reduces activity of complex I and plays a central role in the pathophysiology of the mitochondrial disease MELAS (myopathy, encephalopathy, lactic acidosis and stroke-like episodes). The restoration of mitochondrial levels of the taurine conjugate enhances electron flux through the respiratory chain, thereby preventing at least some of the symptoms of MELAS. Taurine therapy also diminishes the severity of congestive heart failure, an observation that led to its approval for the treatment of congestive heart failure in Japan. The review article discusses the role of defective calcium handling, reduced ATP generation, enhanced oxidative stress and apoptosis in the development of taurine-deficient cardiomyopathy. Some patients suffering from congestive heart failure are taurine-deficient, an observation supporting the hypothesis that low taurine levels contribute to the severity of heart failure. Thus, mishandling of taurine leads to mitochondrial dysfunction, which is involved in the development of both MELAS and congestive heart failure.

Copper-dependent biological effects of particulate matter produced by brake systems on lung alveolar cells

Road traffic is one of the main sources of particulate emissions into the environment and has an increasing, negative impact on the release of potentially dangerous materials. Vehicle brakes release a significant amount of wear particles, and knowledge regarding their possible adverse effects is limited. One of the most dangerous elements contained in brake pads is copper (Cu), known to be toxic for human health. Therefore, our aim was to study the cell toxicity of particulate matter (PM) produced by different combinations of braking discs and pads containing different amounts of Cu. We investigated whether brake-derived microparticles have toxic effects on lung cells proportionally to their Cu content. Analyte content was measured in friction materials by XRFS and in PM2.5 captured during braking tests using SEM/EDX. The biological impact of brake-derived PM2.5 was investigated on a human epithelial alveolar cell line (A549). Cell viability, oxidative stress, mitochondrial membrane potential, apoptosis, and the pro-inflammatory response of the cells, as well as gene expression, were assessed following exposure to increasing PM2.5 concentrations (1, 10, 100, 200, and 500 µg/ml). The brake debris with the lowest Cu content did not induce significant changes in biological effects on A549 cells compared to normal controls, except for ROS production and IL6 gene expression. PM2.5 containing higher Cu quantities induced cell toxicity that correlated with Cu concentration. Our data suggest that the toxicity of PM2.5 from the brake system is mainly related to Cu content, thus confirming that eliminating Cu from brake pads will be beneficial for human health in urbanized environments.

Palmitic Acid Inhibits the Virulence Factors of Candida tropicalis: Biofilms, Cell Surface Hydrophobicity, Ergosterol Biosynthesis, and Enzymatic Activity

Biofilm is the fortitude of Candida species infections which eventually causes candidiasis in human. C. tropicalis is one of the predominant Candida species commonly found in systemic infections, next to C. albicans. In Candida species, biofilm maturity initiates irreversible surface attachment of cells and barricades the penetration of conventional antifungals. Hence, the current study investigated the antifungal and antivirulence potency of palmitic acid (PA) against C. tropicalis mature biofilm and its associated virulence factors. In vitro results revealed an effective inhibition of biofilm in PA-treated C. tropicalis, compared to C. albicans and C. glabrata. Also, PA reduced C. tropicalis mature biofilm at various time points. Further, PA treatment triggered apoptosis in C. tropicalis through ROS mediated mitochondrial dysfunction as demonstrated by confocal microscopic observation of PI, DAPI and DCFDA staining. PA regulated other virulence factors such as cell surface hydrophobicity, ergosterol biosynthesis, protease and lipase after 48 h of treatment. Downregulation of ERG11 (Lanosterol 14-alpha demethylase) was contributed to the reduction of ergosterol in PA-treated C. tropicalis. However, enhanced hyphal growth was observed in PA-treated C. tropicalis through upregulation HWP1 (Hyphal wall protein) and EFG1 (Enhanced filamentous growth). This study highlighted the antibiofilm and antivirulence potency of PA against C. tropicalis. Hence, PA could be applied synergistically with other antifungal agents to increase the efficacy for regulating NCAC infections.

Cytotoxic Activity of Boesenbergia rotunda Extracts against Nasopharyngeal Carcinoma Cells (HK1). Cardamonin, a Boesenbergia rotunda Constituent, Inhibits Growth and Migration of HK1 Cells by Inducing Caspase-Dependent Apoptosis and G2/M-Phase Arrest

Boesenbergia rotunda (L.) Mansf. is an edible herb that is commonly used in the cuisine of several Asian countries. Studies have shown that it possesses high bioactivity against a variety of cancer cells. In this study, we investigated the cytotoxic activity of Boesenbergia rotunda rhizomes and some of its constituents on nasopharyngeal carcinoma cells (HK1). MTT assay results showed that the methanolic and hexane extracts of Boesenbergia rotunda decreased HK1 cell viability with IC₅₀ values of 136 µg/ml and 66 µg/ml, respectively. Cardamonin, a constituent of Boesenbergia rotunda, exhibited the highest cytotoxic activity with an IC₅₀ value of 27 μg/ml. Further studies on cardamonin revealed that it inhibited the migration of HK1 cells, caused G2/M-phase arrest and induced apoptosis. Apoptosis was induced via activating caspase-8 and caspase-3, but independent of caspase-9. This indicated that cardamonin induced extrinsic apoptosis. Western blot analysis further showed that cardamonin caused extrinsic apoptosis, as the expression levels of intrinsic apoptosis-related proteins (Bcl-X_L, Bcl-2 and Bax), were not affected. Finally, JC-1 staining of HK1 cells revealed an increase in the mitochondrial membrane potential after treatment, further proving that cardamonin did not induce apoptosis via the intrinsic pathway. These results reflect cardamonin's potential as an anticancer agent.

Antiproliferative Effect of Acridine Chalcone Is Mediated by Induction of Oxidative Stress

Chalcones are naturally occurring phytochemicals with diverse biological activities including antioxidant, antiproliferative, and anticancer effects. Some studies indicate that the antiproliferative effect of chalcones may be associated with their pro-oxidant effect. In the present study, we evaluated contribution of oxidative stress in the antiproliferative effect of acridine chalcone 1C ((2 E)-3-(acridin-9-yl)-1-(2,6-dimethoxyphenyl)prop-2-en-1-one) in human colorectal HCT116 cells. We demonstrated that chalcone 1C induced oxidative stress via increased reactive oxygen/nitrogen species (ROS/RNS) and superoxide production with a simultaneous weak adaptive activation of the cellular antioxidant defence mechanism. Furthermore, we also showed chalcone-induced mitochondrial dysfunction, DNA damage, and apoptosis induction. Moreover, activation of mitogen activated phosphokinase (MAPK) signalling pathway in 1C-treated cancer cells was also observed. On the other hand, co-treatment of cells with strong antioxidant, N-acetyl cysteine (NAC), significantly attenuated all of the above-mentioned effects of chalcone 1C, that is, decreased oxidant production, prevent mitochondrial dysfunction, DNA damage, and induction of apoptosis, as well as partially preventing the activation of MAPK signalling. Taken together, we documented the role of ROS in the antiproliferative/pro-apoptotic effects of acridine chalcone 1C. Moreover, these data suggest that this chalcone may be useful as a promising anti-cancer agent for treating colon cancer.

Mitochondrial functions and rare diseases

Mitochondria are dynamic cellular organelles responsible for a large variety of biochemical processes as energy transduction, REDOX signaling, the biosynthesis of hormones and vitamins, inflammation or cell death execution. Cell biology studies established that 1158 human genes encode proteins localized to mitochondria, as registered in MITOCARTA. Clinical studies showed that a large number of these mitochondrial proteins can be altered in expression and function through genetic, epigenetic or biochemical mechanisms including the interaction with environmental toxics or iatrogenic medicine. As a result, pathogenic mitochondrial genetic and functional defects participate to the onset and the progression of a growing number of rare diseases. In this review we provide an exhaustive survey of the biochemical, genetic and clinical studies that demonstrated the implication of mitochondrial dysfunction in human rare diseases. We discuss the striking diversity of the symptoms caused by mitochondrial dysfunction and the strategies proposed for mitochondrial therapy, including a survey of ongoing clinical trials.

Serum sphingolipids predict de novo hepatocellular carcinoma in hepatitis C cirrhotic patients with sustained virologic response

BACKGROUND & AIMS

Curing hepatitis C virus (HCV) infection reduces the risk of hepatocellular carcinoma (HCC) development, yet HCC occurs despite sustained virologic response (SVR) in 2%-8% of cirrhotic patients. Sphingolipids (SLs) have been identified as new biomarkers of chronic liver disease and HCC. The aim of this study was to evaluate serum SLs as diagnostic HCC biomarkers in patients with HCV-associated cirrhosis at SVR12.

METHODS

From 2014 to 2016, 166 patients with HCV-cirrhosis and SVR were recruited and SL profiles were measured at baseline and 12 weeks after completion of direct-acting antiviral (DAA) therapy. All patients received HCC surveillance in line with current guideline recommendations. Minimum follow-up period comprised 6 months.

RESULTS

Our study included 130 (78%) patients without history of HCC, 25 (15%) with history of HCC prior DAA therapy and 11 (7%) patients with de novo HCC after FU12. In those with upcoming de novo HCC serum C24DHC (P = 0.006), C24:1DHC (P = 0.048) and C16Cer (P = 0.011) were significantly upregulated at FU12, but not AFP (P = 0.138). Contemporaneous ultrasound did not visualize HCC, at this time. C16Cer stayed sole independent predictor with high diagnostic accuracy of AFP-positive (AUC = 0.741) and -negative (AUC = 0.766) HCC development. Serum SL parameters decreased from baseline to SVR12.

CONCLUSIONS

C24DHC, C24:1DHC and especially C16Cer were superior to AFP in early detection of AFP-positive and -negative de novo HCC development. We observed significant SL profile changes upon SVR. SLs may play a role in non-invasive HCC surveillance and hepatocarcinogenesis.

Selective toxicity of chrysin on mitochondria isolated from liver of a HCC rat model

Flavonoids are natural compounds that show various biological effects, such as the anti-cancer effect. Chrysin is a flavonoid compound found in honey and propolis. Studies have shown that chrysin has anti-cancer activity due to induction of apoptosis signaling. In the present study, we examined the cytotoxic effect of chrysin against liver mitochondria obtained from the hepatocellular carcinoma (HCC) rat model. Diethylnitrosamine (DEN) and 2-acetylaminofluorene (2-AAF) was used for induction of HCC. Mitochondria were isolated from liver hepatocytes using differential centrifugation. Then, hepatocytes and mitochondria markers related to apoptosis signaling were investigated. Our finding indicated an increase in mitochondrial reactive oxygen species (ROS) generation, collapse in the mitochondrial membrane potential (MMP), swelling in mitochondria, and cytochrome c release (about 1.6 fold) after exposure of mitochondria obtained from the HCC rats group with chrysin (10, 20, and 40 µM) compared to the normal rats group. Furthermore, Chrysin was able to increase caspase-3 activity in the HCC rats group (about 2.4 fold) compared to the normal rats group. According to the results, we proposed that chrysin could be considered as a promising complementary therapeutic candidate for the treatment of HCC, but it requires a further in vivo and clinical studies.

Anti-tumor effect of volatile oil from Houttuynia cordata Thunb. on HepG2 cells and HepG2 tumor-bearing mice

The aim of this paper is to study the anti-tumor mechanism of volatile oil from Houttuynia cordata Thunb. (sodium new houttuyfonate, SNH). In vitro, SNH exhibited a concentration-dependent cytotoxic effect against four human cancer lines (HepG2, A2780, MCF-7, SKOV-3). SNH treatment with different concentrations induced HepG2 cells to exhibit varying degrees of morphological changes in apoptotic features, such as round shape, cell shrinkage and formation of apoptotic body. It was observed that SNH caused the decrease in Bcl-2 mRNA expression and triggered the apoptosis of HepG2 cells. Wound healing assay and RT-PCR results showed that the decrease in the expression level of MMP9 and VEGF was observed in HepG2 cells after treatment with SNH for 48 h, suggesting that the extracellular matrix pathway degradation was involved in the HepG2 cells migration. Moreover, we got an insight into the binding mode of SNH into the MMP9 active site through 3D pharmacophore models. Docking study and molecular dynamics (MD) simulation analysis sheds light on that SNH was completely embedded into the MMP9 active site and formed hydrogen bonds with key catalytic residues of MMP9, including Ala191, His190, Ala189 and Glu227. The prediction of SNH binding interaction energies in the MMP9 was almost in good agreement with the original inhibitor EN140. In vivo experiments, both SNH and cyclophosphamide significantly reduced tumor weights and their tumor inhibitory rates were 50.78% and 82.61% respectively. This study demonstrated that SNH was an apoptosis inducer in HepG2 cells. SNH has four possible functions, that it could induce apoptosis by mitochondria pathway in HepG2 cells, inhibit the tumor growth, regulate Bcl-2 family mRNA expression and effectively subdue migration of hepatocellular carcinoma cells by decreasing the expression of MMP9 and VEGF. Therefore, SNH might be a potential candidate drug for the treatment of hepatocellular carcinoma, which could provide a reference for further clinical research.

Nerve growth factor regulates endothelial cell survival and pathological retinal angiogenesis

The mechanism underlying vasoproliferative retinopathies like retinopathy of prematurity (ROP) is hypoxia-triggered neovascularisation. Nerve growth factor (NGF), a neurotrophin supporting survival and differentiation of neuronal cells may also regulate endothelial cell functions. Here we studied the role of NGF in pathological retinal angiogenesis in the course of the ROP mouse model. Topical application of NGF enhanced while intraocular injections of anti-NGF neutralizing antibody reduced pathological retinal vascularization in mice subjected to the ROP model. The pro-angiogenic effect of NGF in the retina was mediated by inhibition of retinal endothelial cell apoptosis. In vitro, NGF decreased the intrinsic (mitochondria-dependent) apoptosis in hypoxia-treated human retinal microvascular endothelial cells and preserved the mitochondrial membrane potential. The anti-apoptotic effect of NGF was associated with increased BCL2 and reduced BAX, as well as with enhanced ERK and AKT phosphorylation, and was abolished by inhibition of the AKT pathway. Our findings reveal an anti-apoptotic role of NGF in the hypoxic retinal endothelium, which is involved in promoting pathological retinal vascularization, thereby pointing to NGF as a potential target for proliferative retinopathies.

MRPL35 Is Up-Regulated in Colorectal Cancer and Regulates Colorectal Cancer Cell Growth and Apoptosis

Mitochondrial ribosome proteins (MRPs), which are encoded by the nuclear genomic DNA, are important for mitochondrial-encoded protein synthesis and mitochondrial function. Emerging evidence suggests that several MRPs also exhibit important extra-mitochondrial functions, such as involvement in apoptosis, protein biosynthesis, and signal transduction. In this study, we demonstrate a significant role of MRP L35 (MRPL35) in colorectal cancer (CRC). The expression of MRPL35 was higher in CRC tissues than in matched cancer-adjacent tissues and higher in CRC cells than in normal mucosal epithelial cells. Higher MRPL35 expression in CRC tissue correlated with shorter overall survival for CRC patients. In vitro, down-regulation of MRPL35 led to increased production of reactive oxygen species (ROS) together with DNA damage, loss of cell proliferation, G₂/M arrest, a decrease in mitochondrial membrane potential, apoptosis, and autophagy induction. MRPL35 knockdown inhibited tumor proliferation in a CRC xenograft nude mouse model. Furthermore, overexpression of MRPL35 or treatment of cells with the ROS scavenger, N-acetyl cysteine, abrogated ROS production, cell cycle arrest, and apoptosis in vitro. These findings suggest that MRPL35 plays an essential role in the development of CRC and may be a potential therapeutic target for CRC.

A Novel Lactate Dehydrogenase Inhibitor, 1-(Phenylseleno)-4-(Trifluoromethyl) Benzene, Suppresses Tumor Growth through Apoptotic Cell Death

The Warburg effect, wherein cancer cells prefer glycolysis rather than oxidative phosphorylation even under normoxic conditions, is a major characteristic of malignant tumors. Lactate dehydrogenase A (LDHA) is the main enzyme regulating the Warburg effect, and is thus, a major target for novel anti-cancer drug development. Through our ongoing screening of novel inhibitors, we found that several selenobenzene compounds have inhibitory effects on LDHA activity. Among them, 1-(phenylseleno)-4-(trifluoromethyl) benzene (PSTMB) had the most potent inhibitory effect on the enzymatic activity of LDHA. The results from biochemical assays and computational modeling showed that PSTMB inhibited LDHA activity. In addition, PSTMB inhibited the growth of several tumor cell lines, including NCI-H460, MCF-7, Hep3B, A375, HT29, and LLC. In HT29 human colon cancer cells, PSTMB dose-dependently inhibited the viability of the cells and activity of LDHA, without affecting the expression of LDHA. Under both normoxic and hypoxic conditions, PSTMB effectively reduced LDHA activity and lactate production. Furthermore, PSTMB induced mitochondria-mediated apoptosis of HT29 cells via production of reactive oxygen species. These results suggest that PSTMB may be a novel candidate for development of anti-cancer drugs by targeting cancer metabolism.

Gambogic acid triggers vacuolization-associated cell death in cancer cells via disruption of thiol proteostasis

Gambogic acid (GA), a xanthonoid extracted from the resin of the tree, Garcinia hanburyi, was recently shown to exert anticancer activity in multiple studies, but the underlying action mechanism remains unclear. Here, we show that GA induces cancer cell death accompanied by vacuolation in vitro and in vivo. This GA-induced vacuolation in various cancer cells was derived from dilation of the endoplasmic reticulum (ER) and mitochondria, and was blocked by cycloheximide. These findings suggest that GA kills cancer cells by inducing paraptosis, a vacuolization-associated cell death. We found that megamitochondria formation, which arose from the fusion of swollen mitochondria, preceded the fusion of ER-derived vacuoles. GA-induced proteasomal inhibition was found to contribute to the ER dilation and ER stress seen in treated cancer cells, and megamitochondria formation was followed by mitochondrial membrane depolarization. Interestingly, GA-induced paraptosis was effectively blocked by various thiol-containing antioxidants, and this effect was independent of ROS generation. We observed that GA can react with cysteinyl thiol to form Michael adducts, suggesting that the ability of GA to covalently modify the nucleophilic cysteinyl groups of proteins may cause protein misfolding and subsequent accumulation of misfolded proteins within the ER and mitochondria. Collectively, our findings show that disruption of thiol proteostasis and subsequent paraptosis may critically contribute to the anti-cancer effects of GA.

Mangrove derived Streptomyces sp. MUM265 as a potential source of antioxidant and anticolon-cancer agents

Background

Colon cancer is the third most commonly diagnosed cancer worldwide, with a commensurately high mortality rate. The search for novel antioxidants and specific anticancer agents which may inhibit, delay or reverse the development of colon cancer is thus an area of great interest; Streptomyces bacteria have been demonstrated to be a source of such agents.

Results

The extract from Streptomyces sp. MUM265— a strain which was isolated and identified from Kuala Selangor mangrove forest, Selangor, Malaysia— was analyzed and found to exhibit antioxidant properties as demonstrated via metal-chelating ability as well as superoxide anion, DPPH and ABTS radical scavenging activities. This study also showed that MUM265 extract demonstrated cytotoxicity against colon cancer cells as evidenced by the reduced cell viability of Caco-2 cell line. Treatment with MUM265 extract induced depolarization of mitochondrial membrane potential and accumulation of subG₁ cells in cell cycle analysis, suggesting that MUM265 exerted apoptosis-inducing effects on Caco-2 cells.

Conclusion

These findings indicate that mangrove derived Streptomyces sp. MUM265 represents a valuable bioresource of bioactive compounds for the future development of chemopreventive agents, with particular promise suggested for treatment of colon cancer.

Electronic supplementary material

The online version of this article (10.1186/s12866-019-1409-7) contains supplementary material, which is available to authorized users.

Effects of nuclear respiratory factor‑1 on apoptosis and mitochondrial dysfunction induced by cobalt chloride in H9C2 cells

Hypoxia-induced apoptosis occurs in various diseases. Cobalt chloride (CoCl₂) is a hypoxia mimic agent that is frequently used in studies investigating the mechanisms of hypoxia. Nuclear respiratory factor-1 (NRF-1) is a transcription factor with an important role in the expression of mitochondrial respiratory and mitochondria-associated genes. However, few studies have evaluated the effects of NRF-1 on apoptosis, particularly with regard to damage caused by CoCl₂. In the present study, the role of NRF-1 in mediating CoCl₂-induced apoptosis was investigated using cell viability analysis, flow cytometry, fluorescence imaging, western blotting analysis, energy metabolism analysis and reverse transcription-quantitative polymerase chain reaction. The present results revealed that the apoptosis caused by CoCl₂ could be alleviated by NRF-1. Furthermore, overexpression of NRF-1 increased the expression of B-cell lymphoma-2, hypoxia inducible factor-1α and NRF-2. Also, cell damage induced by CoCl₂ may be associated with depolarization of mitochondrial membrane potential, and NRF-1 suppressed this effect. Notably, the oxygen consumption rate (OCR) was reduced in CoCl₂-treated cells, whereas overexpression of NRF-1 enhanced the OCR, suggesting that NRF-1 had protective effects. In summary, the present study demonstrated that NRF-1 protected against CoCl₂-induced apoptosis, potentially by strengthening mitochondrial function to resist CoCl₂-induced damage to H9C2 cells. The results of the present study provide a possible way for the investigation of myocardial diseases.

Galectin-9 induces apoptosis in OVCAR-3 ovarian cancer cell through mitochondrial pathway

Galectin-9 (Gal-9), a member of animal lectins' family, is implicated in the induction of apoptosis in various cancer cells. Here, we evaluated the anti-tumor effect of Gal-9 in OVCAR-3 ovarian cancer cells. The effect of the Gal-9 on cell viability was evaluated using MTT assays. Apoptosis was assessed using Annexin-V staining. The assessment of mitochondrial membrane potential (ΔΨm) was performed using a JC-1 probe. The activity of caspase-3 and caspase-6 were evaluated with colorimetric assay. The production of reactive oxygen species (ROS) was applied by fluorescent probe. The expression levels of Bax and Bcl-2 were assessed using western blotting. The result showed that Gal-9 inhibits cell viability. Flow cytometry analysis showed that Gal-9 induces apoptosis in ovarian cancer cells. Moreover, Gal-9 decreased ΔΨm and increased the generation of ROS and caspase-3 and caspase-6 activities in ovarian cancer cells. Moreover, Gal-9 induced expression of Bax as well as inhibited expression of Bcl-2. In conclusion, our results indicated that Gal-9 induced apoptosis in ovarian cancer cells through mitochondrial pathway.

Retinoic acid receptor α expression exerts an anti-apoptosis effect on PC12 cells following oxygen-glucose deprivation

It has been established that the primary form of neuron death following hypoxic ischemic brain damage is apoptosis. Imbalances in the expression of genes in the B-cell lymphoma 2 (Bcl-2) family located in the mitochondrion, and in the expression of their encoded proteins, are key events in the mitochondrial apoptotic pathway, which lead to damage of cellular structure and function. The present study aimed to explore the regulatory effect of retinoic acid receptor α (RAR-α) on the apoptosis of PC12 cells induced by oxygen-glucose deprivation (OGD) in the retinoic acid signaling pathway. Recombinant adenovirus RAR-α small interfering RNA (Ad-siRAR-α) was used to transduce PC12 cells, and the efficiency of RAR-α expression inhibition was detected by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). An empty adenovirus vector was transfected in PC12 cells, which were used as the control. Flow cytometry with Annexin V-propidium iodide (PI) and fluorescence probe JC-1 staining was used to detect the apoptosis rate and mitochondrial transmembrane potential (MMP), respectively, of PC12 cells after transduction with Ad-siRAR-α. Furthermore, the expression levels of key genes in the RAR-α and mitochondrial apoptotic pathway, Bcl-2 and Bcl-2-associated protein (Bax) were analyzed by RT-quantitative (q)PCR and western blot analysis. RAR-α mRNA expression was observed to be decreased in PC12 cells following OGD-induced injury, and this decrease can be reversed by 4 µmol/l ATRA treatment. After 36 h transfection with Ad-siRAR-α, RAR-α gene expression was significantly inhibited compared with the control (P<0.05). The results of Annexin V-PI, fluorescence probe JC-1 staining and flow cytometry demonstrated that the apoptosis rate significantly increased and MMP significantly decreased in OGD-induced PC12 cells following transduction with Ad-siRAR-α compared with the control (both P<0.05). RT-qPCR and western blot analysis indicated that Bax expression was significantly increased and Bcl-2 expression was significantly decreased in PC12 cells transduced with Ad-siRAR-α after OGD-induced injury at the mRNA and protein level (P<0.05). In conclusion, Ad-siRAR-α transduction could promote apoptosis in OGD-induced PC12 cells. This suggests that the expression of Bax and Bcl-2 in the mitochondrial apoptosis signaling pathway is, at least in part, mediated by RAR-α expression, thereby indicating that RAR-α expression exerts an anti-apoptotic effect on OGD-damaged PC12 cells.

Autophagy-dependent apoptosis is triggered by a semi-synthetic [6]-gingerol analogue in triple negative breast cancer cells

Triple negative breast cancer (TNBC) is very aggressive and lacks specific therapeutic targets, having limited treatment options and poor prognosis. [6]-gingerol is the most abundant and studied compound in ginger, presenting diverse biological properties such as antitumor activity against several types of cancer, including breast cancer. In this study, we show that the semi-synthetic analogue SSi6, generated after chemical modification of the [6]-gingerol molecule, using acetone-2,4-dinitrophenylhydrazone (2,4-DNPH) reagent, enhanced selective cytotoxic effects on MDA-MB-231 cells. Remarkably, unlike the original [6]-gingerol molecule, SSi6 enabled autophagy followed by caspase-independent apoptosis in tumor cells. We found a time-dependent association between SSi6-induced oxidative stress, autophagy and apoptosis. Initial SSi6-induced reactive oxygen species (ROS) accumulation (1h) led to autophagy activation (2-6h), which was followed by caspase-independent apoptosis (14h) in TNBC cells. Additionally, our data showed that SSi6 induction of ROS plays a key role in the promotion of autophagy and apoptosis. In order to investigate whether the observed cell death induction was dependent on preceding autophagy in MDA-MB-231 cells, we used siRNA to knock down LC3B prior to SSi6 treatment. Our data show that LC3B downregulation decreased the number of apoptotic cells after treatment with SSi6, indicating that autophagy is a key initial step on SSi6-induced caspase-independent apoptosis. Overall, the results of this study show that structural modifications of natural compounds can be an interesting strategy for developing antitumor drugs, with distinct mechanisms of actions, which could possibly be used against triple negative breast cancer cells that are resistant to canonical apoptosis-inducing drugs.

Bioenergetics of life, disease and death phenomena

In this article, some new aspects of unified cell bioenergetics are presented. From the perspective of unified cell bioenergetics certain subsequent stages of cancer development, from initiation stage, through transformation to metastasis, are analyzed. Here we show that after transformation, cancer cells are permanently exposed to reactive oxygen species, that causes continual random DNA mutations and as a result genome and chromosomal destabilizations. The modern cancer attractor hypothesis has been extended in explaining cancer development. Discussion is conducted in light of current cancerogenesis research, including bioenergetic cancer initiation, the somatic mutation theory and the tissue organization field theory. In the article reasons complicating the discovery of patterns of cancer genome changes and cancer evolution are presented. In addition certain cancer therapeutic aspects are given attention to.

Tanshinone IIA Pretreatment Protects H9c2 Cells against Anoxia/Reoxygenation Injury: Involvement of the Translocation of Bcl-2 to Mitochondria Mediated by 14-3-3η

Tanshinone IIA is an important component that is isolated from danshen (Salvia miltiorrhiza), which is known to be beneficial for cardiovascular health. In this study, we determined the effects of Tanshinone IIA and its underlying mechanisms of action in an anoxia/reoxygenation (A/R) cell line model. Prior to inducing A/R injury, rat cardiomyocyte-derived cell line H9c2 was stimulated with 8 μM of Tanshinone IIA for 48 hours. When compared with the A/R group, the Tanshinone IIA treatment significantly increased cell viability and decreased lactate dehydrogenase activity. Tanshinone IIA upregulated 14-3-3η expression and facilitated Bcl-2 translocation to the mitochondrial outer membrane, which bound with voltage-dependent anion channel 1. In addition, pretreatment with Tanshinone IIA reduced the generation of reactive oxygen species and cytochrome c release, inactivated caspase-3, prevented mitochondrial permeability transition pore opening, and reduced the percentage of apoptotic cells. Moreover, treatment with Tanshinone IIA reduced the level of malondialdehyde, thereby increasing the activity of superoxide dismutase and glutathione peroxidase. Silencing the expression of 14-3-3η by adenovirus blocked the above-mentioned results. These novel findings showed that pretreatment with Tanshinone IIA alleviated H9c2 cell damage against A/R injury and was associated with upregulation of 14-3-3η, thereby facilitating Bcl-2 translocation to the mitochondrial outer membrane and preventing mitochondrial permeability transition pore opening, decreasing cytochrome c release, preventing caspase-3 activation, and restraining apoptosis.

Zoledronic acid induces micronuclei formation, mitochondrial-mediated apoptosis and cytostasis in kidney cells

AIMS

Zoledronic acid (ZA), a FDA approved drug has used widely in the treatment of bone metastasis complications, has been linked to renal toxicity with unclear mechanism. The present study is aimed at investigating the genotoxic and cytotoxic effects of ZA in renal epithelial cells.

MAIN METHODS

The genotoxic effect of ZA in Vero and MDCK cells determined by cytokinesis block micronucleus (CBMN) assay. The cytotoxic effect assessed by analysing cell cycle profile, cell death and mitochondrial membrane potential by flow cytometry using propidium iodide, AnnexinV-FITC/PI and JC1 dye staining, respectively, BAX and Bcl-2 expression by Western blotting and caspase activity by spectrofluorimetry.

KEY FINDINGS

The cytotoxic effect of ZA based on MTT assay revealed variable sensitivities of Vero and MDCK cells, with IC₅₀ values of 7.41 and 109.58 μM, respectively. The CBMN assay has shown prominent dose-dependent (IC_10-50) induction of micronuclei formation in both cells, indicating ZA's clastogenic and aneugenic potential. Further, the ZA treatment led the cells to apoptosis, evident from dose-dependent increase in the percentage of cells in subG1 phase and display of membranous phosphatidylserine translocation. Studies also confirmed apoptosis through mitochondria, evident from the prominent increase in BAX/Bcl-2 ratio, mitochondrial membrane depolarization and caspase-3/7 activity. In addition, ZA reduces cytokinetic activity of renal cells, evident from dose-wise lowered replicative indices.

SIGNIFICANCE

The study depict ZA's potential genotoxic effect along with cytotoxic effect in renal epithelial cells, could be key factors for the development of renal complications associated with it, which prompts renal safety measures in lieu with ZA usage.

Chloroform fraction of Foeniculum vulgare induced ROS mediated, mitochondria-caspase-dependent apoptotic pathway in MCF-7, human breast cancer cell line

ETHNOPHARMACOLOGICAL RELEVANCE

Foeniculum vulgare Mill. (Fennel) is one of the most common herbs used in alternative medicines for its varied range of bioactivity. In Ecuador (South America), use of fennel in traditional cancer treatment is on record.

AIM OF THE STUDY

The objective of the present study was to demonstrate the anti-proliferative and apoptotic effect of chloroform fraction of fennel (CFF) in MCF-7 cells.

MATERIALS AND METHODS

Anti-proliferative assay (MTT assay) and colony formation assay were performed to study the growth inhibitory effect of CFF. Various morphological changes of apoptosis were observed using Giemsa, Hoechst and Acridine orange/ ethidium bromide stains in MCF-7 cells. The extent of apoptosis and cell cycle arrest was measured by flow cytometer. Levels of ROS and mitochondrial membrane potential was measured by DCFH-DA and JC-1 respectively. Caspases activity was measured by luminescence and DNA fragmentation by comet assay.

RESULTS

CFF appeared as a good inhibitor of growth against MCF-7 and MDA-MB-237 in time- and concentration-dependent manners. All the morphological changes of apoptosis were evident in treatment groups. Annexin V/PI-assay of apoptosis gave around 49% of apoptotic cells upon treatment of 0.5 mg/ml of CFF and PI-stained cells showed the G1 phase cell cycle arrest. Elevated levels of ROS, disrupted mitochondrial membrane, increased levels of caspase-9 & caspase-3 and DNA fragmentation were noted in treated MCF-7 cells.

CONCLUSION

Our findings revealed the proliferation inhibition, cell cycle arrest and apoptosis induction effect of CFF, which may help in exploring the novel anti-cancer drug for therapeutic implications.

Ultrafine particulate matter impairs mitochondrial redox homeostasis and activates phosphatidylinositol 3-kinase mediated DNA damage responses in lymphocytes

Particulate matter (PM), broadly defined as coarse (2.5-10 μm), fine (0.1-2.5 μm) and ultrafine particles (≤0.1 μm), is a major constituent of ambient air pollution. Recent studies have linked PM exposure (coarse and fine particles) with several human diseases including cancer. However, the molecular mechanisms underlying ultrafine PM exposure induced cellular and sub-cellular repercussions are ill-defined. Since mitochondria are one of the major targets of different environmental pollutants, we herein aimed to understand the molecular repercussion of ultrafine PM exposure on mitochondrial machinery in peripheral blood lymphocytes. Upon comparative analysis, a significantly higher DCF fluorescence was observed in ultrafine PM exposed cells that confirmed the strong pro-oxidant nature of these particles. In addition, the depleted activity of antioxidant enzymes, glutathione reductase and superoxide dismutase suggested the strong association of ultrafine PM with oxidative stress. These results further coincided with mitochondrial membrane depolarization, altered mitochondrial respiratory chain enzyme activity and decline in mtDNA copy number. Moreover, the higher accumulation of DNA damage response proteins (γH2AX, pATM, p-p53), suggested that exposure to ultrafine PM induces DNA damage and triggers phosphatidylinositol 3 kinase mediated response pathway. Further, the alterations in mitochondrial machinery and redox balance among ultrafine PM exposed cells were accompanied by a considerably elevated pro-inflammatory cytokine response. Interestingly, the lower apoptosis levels observed in ultrafine particle treated cells suggest the possibility that the marked alterations may lead to the impairment of mitochondrial-nuclear cross talk. Together, our results showed that ultrafine PM, because of their smaller size possesses significant ability to disturb mitochondrial redox homeostasis and activates phosphatidylinositol 3 kinase mediated DNA damage response pathway, an unknown molecular paradigm of ultrafine PM exposure. Our findings also indicate that maneuvering through the mitochondrial function might be a viable, indirect method to modulate lymphocyte homeostasis in air pollution associated immune disorders.

Synthesis of new sarsasapogenin derivatives with antiproliferative and apoptotic effects in MCF-7 cells

Sarsasapogenin, a kind of mainly effective component of Anemarrhena asphodeloides Bunge, possesses good antitumor properties. Two series of new sarsasapogenin derivatives were synthesized and evaluated for their cytotoxicities against three human cancer cell lines (HepG2, A549, MCF-7) using the MTT assay. The structure-activity relationship revealed that the N, N-dimethylamino, pyrrolidinyl, and imidazolyl substituted at the C26 position could increase the antitumor efficacy of the 3-oxo sarsasapogenin series of compounds. Compound 4c with pyrrolidinyl substituted at the C26 position exhibited the greatest cytotoxic activity against MCF-7 cell line (IC₅₀ = 10.66 μM), which was 4.3-fold more potent than sarsasapogenin. Action mechanism investigations showed that 4c could inhibit the colony formation and induce the apoptosis of MCF-7 cells. Further researches showed that a decrease in mitochondrial membrane potential and increases in the expression level of cleaved-PARP and the ratio of Bax/Bcl-2 were observed in MCF-7 cells after treatment with 4c, suggesting that the mitochondrial pathway was involved in the 4c-mediated apoptosis. These results show that compound 4c may serve as a lead for further optimization.