Eupalinin A isolated from Eupatorium chinense L. induces autophagocytosis in human leukemia HL60 cells

The Role of Reactive Oxygen Species in Tumor Treatment and its Impact on Bone Marrow Hematopoiesis

Reactive oxygen species (ROS), an important molecule inducing oxidative stress in organisms, play a key role in tumorigenesis, tumor progression and recurrence. Recent findings on ROS have shown that ROS can be used to treat cancer as they accelerate the death of tumor cells. At present, pro-oxidant drugs that are intended to increase ROS levels of the tumor cells have been widely used in the clinic. However, ROS are a double-edged sword in the treatment of tumors. High levels of ROS induce not only the death of tumor cells but also oxidative damage to normal cells, especially bone marrow hemopoietic cells, which leads to bone marrow suppression and (or) other side effects, weak efficacy of tumor treatment and even threatening patients' life. How to enhance the killing effect of ROS on tumor cells while avoiding oxidative damage to the normal cells has become an urgent issue. This study is a review of the latest progress in the role of ROS-mediated programmed death in tumor treatment and prevention and treatment of oxidative damage in bone marrow induced by ROS.

Autophagy regulation and its role in normal and malignant hematopoiesis

Autophagy, the molecular machinery of self-eating, plays a dual role of a tumor promoter and tumor suppressor. This mechanism affects different clinical responses in cancer cells. Autophagy is targeted for treating patients resistant to chemotherapy or radiation. Limited reports investigate the significance of autophagy in cancer therapy, the regulation of hematopoietic and leukemic stem cells and leukemia formation. In the current review, the role of autophagy is discussed in various stages of hematopoiesis including quiescence, self-renewal, and differentiation.

Apoptotic and Anti-Inflammatory Effects of Eupatorium japonicum Thunb. in Rheumatoid Arthritis Fibroblast-Like Synoviocytes

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease characterized by synovitis, hyperplasia, and the destruction of bone and cartilage. A variety of immunosuppressive biological agents have been developed because the pathogenesis of RA is related predominantly to the inflammatory response. However, rheumatoid arthritis fibroblast-like synovial cells (RAFLS), which are known to play an important role in RA progression, exhibit resistance to immunosuppressants through cancer-like properties. In this study, we identified a novel therapeutic compound for RA, which reduced inflammation and the abnormal proliferation of RAFLS in natural product library made from Korean native plants. Eupatorium japonicum Thunb. (EJT) extract, a component of the natural product library, most effectively reduced viability through the induction of ROS-mediated apoptosis in a dose-dependent manner. In addition, the increased ROS induced the expression of ATF4 and CHOP, key players in ER stress-mediated apoptosis. Interestingly, EJT extract treatment dose-dependently reduced the expression of IL-1β and the transcription of MMP-9, which were induced by TNF-α treatment, through the inhibition of NF-κB and p38 activation. Collectively, we found that EJT extract exerted apoptotic effects through increases in ROS production and CHOP expression and exerted anti-inflammatory effects through the suppression of NF-κB activation, IL-1β expression, and MMP-9 transcription.

Germacrane-Type Sesquiterpenoids with Antiproliferative Activities from Eupatorium chinense

Ten new germacrane-type sesquiterpenoids (1-10) were isolated from a whole plant extract of Eupatorium chinense. The structures were elucidated by analysis of their NMR and MS data as well as by comparison with literature values. The absolute configuration of eupachinsin A (1) was determined by single-crystal X-ray diffraction analysis. Compounds 3 and 4 exhibited cytotoxicity against a human breast cancer cell line (MDA-MB-231), with IC₅₀ values of 0.8 and 3.4 μM, respectively. In addition, compounds 3-5 showed cytotoxicity against the human hepatocellular carcinoma cell line (HepG₂), with IC₅₀ values ranging from 3.6 to 7.6 μM.

The roles of reactive oxygen species (ROS) and autophagy in the survival and death of leukemia cells

As a clonal disease of hematopoietic stem cells (HSCs), the etiology and pathogenesis of leukemia is not fully understood. Recent studies suggest that cellular homeostasis plays an essential role in maintaining the function of HSCs because dysregulation of cellular homeostasis is one of the major factors underlying the malignant transformation of HSCs. Reactive oxygen species (ROS) and autophagy, key factors regulating cellular homeostasis, are commonly observed in the human body. Autophagy can be induced by ROS through a variety of signaling pathways, and conversely inhibits ROS-induced damage to cells and tissues. ROS and autophagy coordinate to maintain cellular homeostasis. Previous studies have demonstrated that both of ROS and autophagy play important roles in the development of leukemia and are closely involved in drug resistance in leukemia. Interference with cellular homeostasis by promoting programmed leukemia cell death via ROS and autophagy has been verified to be an efficient technique in the treatment of leukemia. However, the critical roles of ROS and autophagy in the development of leukemia are largely unknown. In this review, we summarize the roles of ROS and autophagy in the pathogenesis of leukemia, which may allow the identification of novel targets and drugs for the treatment of leukemia based on the regulation of HSCs homeostasis through ROS and autophagy.

NADPH oxidase activation is required for pentylenetetrazole kindling-induced hippocampal autophagy

Growing evidence indicates that alterations in autophagy are present in a variety of neurological disorders, ranging from neurodegenerative diseases to acute neurological insults. Only recently has the role of autophagy in epilepsy started to be recognized. In this study, we used pentylenetetrazole (PTZ) kindling, which provides a model of chronic epilepsy, to investigate the involvement of autophagy in the hippocampus and the possible mechanisms involved. Our western blot results showed that autophagy-related proteins were significantly increased after the mice were fully kindled. In addition, immunofluorescence studies revealed a significant increase in the punctate accumulation of LC3 in the hippocampal CA1 region of fully PTZ-kindled mice. Consistent with the upregulation of ATG proteins and punctate accumulation of LC3 in the hippocampal CA1 region, autophagosomal vacuole formation was observed by an ultrastructural analysis, verifying the presence of a hippocampal autophagic response in PTZ-kindled mice. Increased oxidative stress has been postulated to play an important role in the pathogenesis of a number of neurological diseases, including epilepsy. In this study, we demonstrate that PTZ kindling induced reactive oxygen species (ROS) production and lipid peroxidation, which were accompanied by mitochondrial ultrastructural damage due to the activation of NADPH oxidase. Pharmacological inhibition of NADPH oxidase by apocynin significantly suppressed the oxidative stress and ameliorated the hippocampal autophagy in PTZ-kindled mice. Interestingly, pharmacological induction of autophagy suppressed PTZ-kindling progress and reduced PTZ-kindling-induced oxidative stress while inhibition of autophagy accelerated PTZ kindling progress and increased PTZ-kindling-induced oxidative stress. These results suggest that the oxidative stress induced by NADPH oxidase activation may play a pivotal role in PTZ-kindling process as well as in PTZ kindling-induced hippocampal CA1 autophagy.

SIRT1 positively regulates autophagy and mitochondria function in embryonic stem cells under oxidative stress

SIRT1, an NAD-dependent deacetylase, plays a role in regulation of autophagy. SIRT1 increases mitochondrial function and reduces oxidative stress, and has been linked to age-related reactive oxygen species (ROS) generation, which is highly dependent on mitochondrial metabolism. H2O2 induces oxidative stress and autophagic cell death through interference with Beclin 1 and the mTOR signaling pathways. We evaluated connections between SIRT1 activity and induction of autophagy in murine (m) and human (h) embryonic stem cells (ESCs) upon ROS challenge. Exogenous H2 O2 (1 mM) induced apoptosis and autophagy in wild-type (WT) and Sirt1-/- mESCs. High concentrations of H2O2 (1 mM) induced more apoptosis in Sirt1-/-, than in WT mESCs. However, addition of 3-methyladenine, a widely used autophagy inhibitor, in combination with H2O2 induced more cell death in WT than in Sirt1-/- mESCs. Decreased induction of autophagy in Sirt1-/- mESCs was demonstrated by decreased conversion of LC3-I to LC3-II, lowered expression of Beclin-1, and decreased LC3 punctae and LysoTracker staining. H2O2 induced autophagy with loss of mitochondrial membrane potential and disruption of mitochondrial dynamics in Sirt1-/- mESCs. Increased phosphorylation of P70/85-S6 kinase and ribosomal S6 was noted in Sirt1-/- mESCs, suggesting that SIRT1 regulates the mTOR pathway. Consistent with effects in mESCs, inhibition of SIRT1 using Lentivirus-mediated SIRT1 shRNA in hESCs demonstrated that knockdown of SIRT1 decreased H2O2-induced autophagy. This suggests a role for SIRT1 in regulating autophagy and mitochondria function in ESCs upon oxidative stress, effects mediated at least in part by the class III PI3K/Beclin 1 and mTOR pathways.

Interplay between apoptosis and autophagy, a challenging puzzle: new perspectives on antitumor chemotherapies

Autophagy is a mechanism of protection against various forms of human diseases, such as cancer, in which autophagy seems to have an extremely complex role. In cancer, there is evidence that autophagy may be oncogenic in some contexts, whereas in others it clearly contributes to tumor suppression. In addition, studies have demonstrated the existence of a complex relationship between autophagy and cell death, determining whether a cell will live or die in response to anticancer therapies. Nevertheless, we still need to complete the autophagy-apoptosis puzzle in the tumor context to better address appropriate chemotherapy protocols with autophagy modulators. Generally, tumor cell resistance to anticancer induced-apoptosis can be overcome by autophagy inhibition. However, when an extensive autophagic stimulus is activated, autophagic cell death is observed. In this review, we discuss some details of autophagy and its relationship with tumor progression or suppression, as well as role of autophagy-apoptosis in cancer treatments.

Targeting metabolism and autophagy in the context of haematologic malignancies

Autophagy is a cellular process that maintains the homeostasis of the normal cell. It not only allows for cell survival in times of metabolic stress with nutrient recycling but also is able to lead to cell death when required. During malignant transformation the cell is able to proliferate and survive. This is due to altered cell metabolism and the presence of altered genetic changes that maintain the cell survival. Metabolism was considered an innocent bystander that was a consequence of the increased nutrient requirement for the survival and proliferation of haematological malignancies. The interdependency of metabolism and cellular mechanisms such as autophagy are becoming more evident and important. This interdependence contributes to increased cancer progression and drug resistance. In this paper we aim to discuss autophagy, how it pertains to metabolism in the context of hematologic malignancies, and the implications for therapy.

Autophagy is induced by 3β-O-succinyl-lupeol (LD9-4) in A549 cells via up-regulation of Beclin 1 and down-regulation mTOR pathway

The purpose of this study is to investigate the antitumor activity of a new derivative of lupeol-3β-O-succinyl-lupeol (LD9-4) and the molecular mechanism underlying cell death in human non-small cell lung cancer A549 cells. The results revealed that LD9-4 inhibited A549 cell proliferation in a time- and dose-dependent manner, with an IC(50) value of 5.78 ± 0.48 μM after cells exposed to LD9-4 for 72 h. Markers indicative of apoptosis (cell cycle arrest, phosphatidylserine externalization and Hoechst33258 staining) were uniformly negative in LD9-4 exposed cells. Interestingly, transmission electron microscope, MDC staining and LC3 level determination all confirmed that autophagy was induced in LD9-4 treated A549 cells. Furthermore, we found that LD9-4-induced autophagy in A549 cells was associated with the increase of intracellular reactive oxygen species and the decrease of phosphorylated mTOR and p70S6K levels. In the meanwhile, both mRNA and protein levels of Beclin 1 were up-regulated in a time-dependent manner. Our data suggest that autophagy is induced by LD9-4 in A549 cells, and the accumulating reactive oxygen species, up-regulation of Beclin 1 and inhibition of the mTOR signaling pathway are involved in this process.

Antitumor effect of matrine in human hepatoma G2 cells by inducing apoptosis and autophagy

AIM: To study the antitumor effect of matrine in human hepatoma G2 (HepG2) cells and its molecular mechanism involved in antineoplastic activities.

METHODS: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to detect viability of HepG2 cells. The effect of matrine on cell cycle was detected by flow cytometry. Annexin-V-FITC/PI double staining assay was used to detect cellular apoptosis. Cellular morphological changes were observed under an inverted phase contrast microscope. Transmission electron microscopy was performed to further examine ultrastructural structure of the cells treated with matrine. Monodansylcadaverine (MDC) staining was used to detect autophagy. Whether autophagy is blocked by 3-methyladenine (3-MA), an autophagy inhibitor, was evaluated. Expression levels of Bax and Beclin 1 in HepG2 cells were measured by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS: Matrine significantly inhibited the proliferation of HepG2 cells in a dose- and time-dependent manner, and induced G1-phase cell cycle arrest and apoptosis of HepG2 cells in a dose-dependent manner. The total apoptosis rate was 0.14% for HepG2 cells not treated with matrine. In contrast, the apoptosis rate was 28.91%, 34.36% and 38.80%, respectively, for HepG2 cells treated with matrine at the concentration of 0.5, 1.0 and 2.0 mg/mL. The remarkable morphological changes were observed under an inverted phase contrast microscope. Abundant cytoplasmic vacuoles with varying sizes were observed in HepG2 cells treated with matrine. Furthermore, vacuolization in cytoplasm progressively became larger and denser when the concentration of matrine was increased. Electron microscopy demonstrated formation of abundant autophagic vacuoles in HepG2 cells after matrine treatment. When the specific autophagic inhibitor, 3-MA, was applied, the number of autophagic vacuoles greatly decreased. MDC staining showed that the fluorescent density was higher and the number of MDC-labeled particles in HepG2 cells was greater in matrine treatment group than in control group. Fewer autophagic vacuoles were observed in the combined 3-MA and matrine treatment group when 3-MA was added before matrine treatment, indicating that both autophagy and apoptosis are activated when matrine-induced death of hepatoma G2 cells occurs. Real-time quantitative RT-PCR revealed that the expression levels of Bax gene, an apoptosis-related molecule, and Beclin 1 gene which plays a key role in autophagy were higher in matrine treatment group than in control group, indicating that Beclin 1 is involved in matrine-induced autophagy and the pro-apoptotic mechanism of matrine may be related to its upregulation of Bax expression.

CONCLUSION: Matrine has potent antitumor activities in HepG2 cells and may be used as a novel effective reagent in treatment of hepatocellular carcinoma.

Molecular pathogenesis of a novel mutation, G108D, in short-chain acyl-CoA dehydrogenase identified in subjects with short-chain acyl-CoA dehydrogenase deficiency

Short-chain acyl-CoA dehydrogenase (SCAD) is a mitochondrial enzyme involved in the beta-oxidation of fatty acids. Genetic defect of SCAD was documented to cause clinical symptoms such as progressive psychomotor retardation, muscle hypotonia, and myopathy in early reports. However, clinical significance of SCAD deficiency (SCADD) has been getting ambiguous, for some variants in the ACADS gene, which encodes the SCAD protein, has turned out to be widely prevailed among general populations. Accordingly, the pathophysiology of SCADD has not been clarified thus far. The present report focuses on two suspected cases of SCADD detected through the screening of newborns by tandem mass spectrometry. In both subjects, compound heterozygous mutations in ACADS were detected. The mutated genes were expressed in a transient gene expression system, and the enzymatic activities of the obtained mutant SCAD proteins were measured. The activities of the mutant SCAD proteins were significantly lower than that of the wild-type enzyme, confirming the mechanism underlying the diagnosis of SCADD in both subjects. Moreover, the mutant SCAD proteins gave rise to mitochondrial fragmentation and autophagy, both of which were proportional to the decrease in SCAD activities. The association of autophagy with programmed cell death suggests that the mutant SCAD proteins are toxic to mitochondria and to the cells in which they are expressed. The expression of recombinant ACADS-encoded mutant proteins offers a technique to evaluate both the nature of the defective SCAD proteins and their toxicity. Moreover, our results provide insight into possible molecular pathophysiology of SCADD.

Oxidative stress induces parallel autophagy and mitochondria dysfunction in human glioma U251 cells

Accumulation of reactive oxygen species (ROS) such as hydrogen peroxide (H(2)O(2)) is an oxidative stress response, which induced various defense mechanisms or programmed cell death (PCD). As one of the major types of PCD, autophagy has been observed in response to several anticancer drugs and demonstrated to be responsible for cell death. To date, however, the exact mechanism by which ROS regulates autophagy is still poorly understood. Thus, the purposes of this study were to elucidate how H(2)O(2) exerts its cytotoxic effects on malignant glioma U251 cells and to uncover the molecular mechanism that might be involved. Here, we show that H(2)O(2)-induced autophagy and apoptosis in U251 cells are mediated through the Beclin 1 and Akt/mTOR pathways. Accumulation of ROS leads to changes in mitochondrial permeability with loss of mitochondrial membrane potential and disruption of mitochondrial dynamics at a transcriptional level of fission and fusion. Overexpression of cellular Bcl-2 partially inhibited autophagy through both the Beclin 1 and the Akt/mTOR pathways and led to recovery of mitochondrial dynamics. When autophagy was prevented at an early stage by 3-methyladenine, apoptosis significantly increased. Our data provide the first evidence that H(2)O(2) induces autophagy through interference with the Beclin 1 and Akt/mTOR signaling pathways and is regulated by the anti-apoptotic gene Bcl-2 in glioma U251 cells.

Inhibitory effects of sesquiterpene lactones isolated from Eupatorium chinense L. on IgE-mediated degranulation in rat basophilic leukemia RBL-2H3 cells and passive cutaneous anaphylaxis reaction in mice

Sesquiterpene lactones (SQTLs) have been shown to suppress the degranulation as inferred by histamine release in rat basophilic leukemia RBL-2H3 cells. In this study, we isolated the 9 kinds of SQTLs from Eupatorium chinense L. and examined the effects of these SQTLs on the degranulation in RBL-2H3 cells. The chemical structures of two novel compounds (SQTL-3 and 8) were determined. All the SQTLs suppressed the degranulation from Ag-stimulated RBL-2H3 cells. To disclose the inhibitory mechanism of degranulation by SQTLs, we examined the activation of intracellular signaling molecules such as Lyn, Syk, and PLCgammas and intracellular free Ca(2+) concentration ([Ca(2+)]i). None of these SQTLs showed the activation of Syk and PLCgammas. The intracellular free Ca(2+) concentration ([Ca(2+)]i) was elevated by Fc epsilonRI activation, but SQTLs treatment reduced the elevation of [Ca(2+)]i by suppressing Ca(2+) influx. Thus, it was suggested that the suppression of Ag-stimulated degranulation by these SQTLs is mainly due to the decreased Ca(2+) influx. Furthermore, in order to clarify the in vivo effect of SQTL-rich extract, we administered SQTL-rich extract to the type I allergic model mice and measured the passive cutaneous anaphylaxis (PCA) reaction induced by IgE-antigen complex. The SQTLs remarkably suppressed PCA reaction in a dose-dependent manner. Thus, it was suggested that SQTLs would be a candidate as an anti-allergic agent.

A novel diquinolonium displays preclinical anti-cancer activity and induces caspase-independent cell death

Quinolines are a class of chemical compounds with emerging anti-cancer properties. Here, we tested the activity of series of quinolines and quinoline-like molecules for anti-cancer activity and identified a novel diquinoline, 1-methyl-2-[3-(1-methyl-1,2-dihydroquinolin-2-yliden)prop-1-enyl]quinolinium iodide (Q(2)). Q(2 )induced cell death in leukemia, myeloma, and solid tumor cell lines with LD50s in the low to submicromolar range. Moreover, Q(2) induced cell death in primary acute myeloid leukemia (AML) cells preferentially over normal hematopoietic cells. In a mouse model of leukemia, Q(2) delayed tumor growth. Mechanistically, Q(2) induced cell death through caspase independent mechanisms. By electron microscopy, Q(2) increased cytoplasmic vacuolization and mitochondrial swelling. Potentially consistent with the induction of autophagic cell death, Q(2) treatment led to a punctate distribution of LC3 and increased MDC staining. Thus, Q(2) is a novel quinolinium with preclinical activity in malignancies such as leukemia and myeloma and warrants further investigation.