Life and death partners: apoptosis, autophagy and the cross-talk between them. Cell Death Differ. 2009;16:966-975. [PMID: 19325568 DOI: 10.1038/cdd.2009.33]

The Antitumor Activity of a Novel Fluorobenzamidine against Dimethylhydrazine- Induced Colorectal Cancer in Rats

BACKGROUND

Colorectal cancer is among the leading causes of death worldwide. The incidence of deaths is expected to be 11.4 million in 2030.

OBJECTIVE

We aimed to evaluate the in vitro and in vivo antioxidant and antitumor activities of a novel Bithiophene- Fluorobenzamidine (BFB) against DMH-induced colorectal cancer in rats.

METHODS

The antiproliferative activity of BFB against HCT-116 colon cancer cells and apoptotic genes was assessed. In vivo study was also conducted in which 80 adult male rats were divided into 5 groups; control, BFB, and the other 3 groups were injected with DMH (20mg/kg, s.c., for 9 weeks). Group 4 was injected with 5 doses of cisplatin (2.5mg/kg, i.p over 21 weeks) and group 5 was injected with 3 doses/week of BFB (2.5mg/kg, i.p, for 21 weeks).

RESULTS

BFB exhibited weak to moderate in vitro antioxidant activity. It had a strong antiproliferative activity with IC50 ~0.3µg/ml. BFB induced extrinsic apoptosis through the upregulation of FasL, TRAL, p53 and caspase-8, and intrinsic apoptosis through the downregulation of Bcl-2 and survivin. BFB decreased the tumor incidence, multiplicity and size and improved the decreased body weight. BFB also ameliorated the functions of kidney and liver and antioxidants deteriorated by DMH. BFB significantly improved the pathological changes caused by DMH in colon tissues.

CONCLUSION

BFB showed a very promising antitumor activity against colorectal cancer induced by DMH in rats without causing hepato- or nephrotoxicity.

More serious autophagy can be induced by ZnO nanoparticles than single-walled carbon nanotubes in rat tracheal epithelial cells

Metal oxide nanoparticles and carbon nanoparticles, as common nanoparticles (NPs), can cause autophagy in certain cells, which will lead to biohealth risk issues. This study determined the difference in autophagy induced by zinc oxide nanoparticles (ZnO NPs) and single-walled carbon nanotubes (SWCNTs) in respiratory epithelial cells. ICP-OES results showed that NPs uptake as well as the intercellular contents of particles affected cytotoxicity in a dose-dependent manner. ZnO NPs-30 nm had a distinct green dot structure representing autophagy, the SWCNTs exposure group had a few green light spots at a concentration of 10 μg/L. The ROS content of the ZnO NP-30 nm exposure group had the greatest increase at a concentration of 1000 μg/L, which was 2.5 times higher than that of the control, the SWCNTs exposure group showed a 2.2-fold increase. A slight downregulation of p-mTOR was detected, and the ZnO NPs-30 nm treatment group had the significant downregulation rate. The gene and protein expression levels of Beclin-1 and LC3B were upregulated as the exposure concentration increased. The protein expression of Beclin-1 and LC3B in the 1000 μg/L ZnO NPs-30 nm exposure group were 5.21 times and 4.12 times that of the control, respectively. The mRNA expression of Beclin-1 and LC3B in the 1000 μg/L ZnO NPs-30 nm exposure group were 5.04 times and 3.61 times that of the control, respectively. At any concentration, the effect of ZnO NPs-30 nm was greater than that of the SWCNTs. Interaction and crosstalk analysis showed that exposure to ZnO NPs-30 nm caused autophagy through the aggregation of undegraded autophagosomes, whereas SWCNTs exposure induced diminished intercellular oxidative stress to inhibit autophagy. Therefore, this study demonstrated that the effects of autophagy induced by ZnO NPs-30 nm and SWCNTs were different. The health risks of ZnO-30 nm NPs are higher than those of SWCNTs.

Deciphering the Role of Autophagy in Treatment of Resistance Mechanisms in Glioblastoma

Autophagy is a process essential for cellular energy consumption, survival, and defense mechanisms. The role of autophagy in several types of human cancers has been explicitly explained; however, the underlying molecular mechanism of autophagy in glioblastoma remains ambiguous. Autophagy is thought to be a “double-edged sword”, and its effect on tumorigenesis varies with cell type. On the other hand, autophagy may play a significant role in the resistance mechanisms against various therapies. Therefore, it is of the utmost importance to gain insight into the molecular mechanisms deriving the autophagy-mediated therapeutic resistance and designing improved treatment strategies for glioblastoma. In this review, we discuss autophagy mechanisms, specifically its pro-survival and growth-suppressing mechanisms in glioblastomas. In addition, we try to shed some light on the autophagy-mediated activation of the cellular mechanisms supporting radioresistance and chemoresistance in glioblastoma. This review also highlights autophagy’s involvement in glioma stem cell behavior, underlining its role as a potential molecular target for therapeutic interventions.

Autophagy in liver diseases

Autophagy is the liver cell energy recycling system regulating a variety of homeostatic mechanisms. Damaged organelles, lipids and proteins are degraded in the lysosomes and their elements are re-used by the cell. Investigations on autophagy have led to the award of two Nobel Prizes and a health of important reports. In this review we describe the fundamental functions of autophagy in the liver including new data on the regulation of autophagy. Moreover we emphasize the fact that autophagy acts like a two edge sword in many occasions with the most prominent paradigm being its involvement in the initiation and progress of hepatocellular carcinoma. We also focused to the implication of autophagy and its specialized forms of lipophagy and mitophagy in the pathogenesis of various liver diseases. We analyzed autophagy not only in well studied diseases, like alcoholic and nonalcoholic fatty liver and liver fibrosis but also in viral hepatitis, biliary diseases, autoimmune hepatitis and rare diseases including inherited metabolic diseases and also acetaminophene hepatotoxicity. We also stressed the different consequences that activation or impairment of autophagy may have in hepatocytes as opposed to Kupffer cells, sinusoidal endothelial cells or hepatic stellate cells. Finally, we analyzed the limited clinical data compared to the extensive experimental evidence and the possible future therapeutic interventions based on autophagy manipulation.

Synthetic Cannabinoids Induce Autophagy and Mitochondrial Apoptotic Pathways in Human Glioblastoma Cells Independently of Deficiency in TP53 or PTEN Tumor Suppressors

Simple Summary

Glioblastomas (GBMs) are aggressive brain tumors with frequent genetic defects in TP53 and PTEN tumor suppressor genes, which render tumors refractory to standard chemotherapeutics. Natural and synthetic cannabinoids showed antitumor activity in glioma cells and animal glioma models. Due to differences in the expression of cannabinoid type 2 receptors (CB2), which are abundant in GBMs but absent from a healthy brain, we tested synthetic cannabinoids for their ability to kill numerous glioma cells. We performed multiple biochemical analyses to determine which cell death pathways are activated in human glioma cells. We demonstrate high susceptibility of human glioblastoma cells to synthetic cannabinoids, despite genetic defects contributing to apoptosis resistance, which makes cannabinoids promising anti-glioma therapeutics.

Abstract

Glioblastomas (GBMs) are aggressive brain tumors with frequent genetic alterations in TP53 and PTEN tumor suppressor genes rendering resistance to standard chemotherapeutics. Cannabinoid type 1 and 2 (CB1/CB2) receptor expression in GBMs and antitumor activity of cannabinoids in glioma cells and animal models, raised promises for a targeted treatment of these tumors. The susceptibility of human glioma cells to CB2-agonists and their mechanism of action are not fully elucidated. We determined CB1 and CB2 expression in 14 low-grade and 21 high-grade tumor biopsies, GBM-derived primary cultures and established cell lines. The non-selective CB receptor agonist WIN55,212-2 (but not its inactive enantiomer) or the CB2-selective agonist JWH133 induced apoptosis in patient-derived glioma cultures and five established glioma cell lines despite p53 and/or PTEN deficiency. Growth inhibitory efficacy of cannabinoids correlated with CB1/CB2 expression (EC₅₀ WIN55,212-2: 7.36–15.70 µM, JWH133: 12.15–143.20 µM). Treatment with WIN55,212-2 or JWH133 led to activation of the apoptotic mitochondrial pathway and DNA fragmentation. Synthetic cannabinoid action was associated with the induction of autophagy and knockdown of autophagy genes augmented cannabinoid-induced apoptotic cell death. The high susceptibility of human glioblastoma cells to synthetic cannabinoids, despite genetic defects contributing to apoptosis resistance, makes cannabinoids promising anti-glioma therapeutics.

Chitopentaose inhibits hepatocellular carcinoma by inducing mitochondrial mediated apoptosis and suppressing protective autophagy

Hepatocellular carcinoma (HCC) is one of the most prevalent and deadliest cancers. In this study, the anti-tumor effect of singular degree of polymerization (DP) chitooligosaccharides (COS) (DP 2-5) and the underlay molecular mechanisms were investigated on HCC cell line HepG2. MTT assay showed that (GlcN)5 have the best anti-proliferation effect among the different DP of COS (DP2-5). Furthermore, the administration of (GlcN)5 could decrease mitochondrial membrane potential, release cytochrome c into cytoplasm, activate the cleavage of Caspases9/3, thus inducing mitochondrial-mediated apoptosis in HepG2 cells (accounting for 24.57 ± 2.25%). In addition, (GlcN)5 treatment could increase the accumulation of autophagosomes. Further investigation showed that (GlcN)5 suppressed protective autophagy at the fusion of autophagosomes and lysosomes. Moreover, the inhibition of protective autophagy flux by (GlcN)5 could further decrease cell viability and increase the apoptosis rate. Our findings suggested that (GlcN)5 suppressed HepG2 proliferation through inducing apoptosis via the intrinsic pathway and impairing cell-protective autophagy. COS might have the potential to be an agent for lowering the risk of HCC.

A Review of APOE Genotype-Dependent Autophagic Flux Regulation in Alzheimer's Disease

Autophagy is a basic physiological process maintaining cell renewal, the degradation of dysfunctional organelles, and the clearance of abnormal proteins and has recently been identified as a main mechanism underlying the onset and progression of Alzheimer's disease (AD). The APOE ɛ4 genotype is the strongest genetic determinant of AD pathogenesis and initiates autophagic flux at different times. This review synthesizes the current knowledge about the potential pathogenic effects of ApoE4 on autophagy and describes its associations with the biological hallmarks of autophagy and AD from a novel perspective. Via a remarkable variety of widely accepted signaling pathway markers, such as mTOR, TFEB, SIRT1, LC3, p62, LAMP1, LAMP2, CTSD, Rabs, and V-ATPase, ApoE isoforms differentially modulate autophagy initiation; membrane expansion, recruitment, and enclosure; autophagosome and lysosome fusion; and lysosomal degradation. Although the precise pathogenic mechanism varies for different genes and proteins, the dysregulation of autophagic flux is a key mechanism on which multiple pathogenic processes converge.

Autophagy attenuates particulate matter 2.5-induced damage in HaCaT cells

Background

Keratinocyte is a key component of the skin barrier and maintains skin homeostasis. As an environmental pathogenic factor, PM2.5 can cause epidermal cell damage, but the mechanism remains to be elucidated. The present study aimed to evaluate the effect caused by PM2.5 in HaCaT cells and investigate the underlying mechanisms.

Methods

HaCaT cells were treated with PM2.5 for 12 h or 24 h, either alone or combined with UVB irradiation. A Cell Counting Kit (CCK-8) assay was carried out to detect the effect of PM2.5 on HaCaT cell viability. Flow cytometry, Western Blot, and AO staining were employed to detect the changes of apoptosis and autophagy. The changes of cytotoxicity and apoptosis in HaCaT cells were analyzed by CCK-8 and flow cytometry after pretreatment with autophagy inhibitor 3-MA.

Results

The results showed that PM2.5 induced cytotoxicity by increasing cell apoptosis and activating autophagy. Apoptosis was determined to be increased significantly after autophagy inhibition. Moreover, solar radiation intensified PM2.5-induced damage in HaCaT cells, which further enhanced the autophagy. However, there was no significant difference in apoptosis after inhibition of autophagy in combined treatment.

Conclusions

Our data reveals that PM2.5 induces damage in HaCaT cells, and autophagy plays a protective role to promote cell survival.

Effect of Bitis gabonica and Dendroaspis angusticeps snake venoms on apoptosis-related genes in human thymic epithelial cells

Background:

Certain environmental toxins permanently damage the thymic epithelium, accelerate immune senescence and trigger secondary immune pathologies. However, the exact underlying cellular mechanisms and pathways of permanent immune intoxication remain unknown. The aim of the present study was to demonstrate gene expressional changes of apoptosis-related cellular pathways in human thymic epithelial cells following exposure to snake venom from Bitis gabonica and Dendroaspis angusticeps.

Methods:

Snake venoms were characterized by analytical methods including reversed phase high-performance liquid chromatography and sodium dodecyl sulphate-polyacrylamide gel electrophoresis, then applied on human thymic epithelial cells (1889c) for 24 h at 10 μg/mL (as used in previous TaqMan Array study). Gene expressional changes restricted to apoptosis were assayed by TaqMan Array (Human Apoptosis Plate).

Results:

The most prominent gene expressional changes were shown by CASP5 (≈ 2.5 million-fold, confirmed by dedicated quantitative polymerase chain reaction) and CARD9 (0.016-fold) for B. gabonica, and BIRC7 (6.46-fold) and CASP1 (0.30-fold) for D. angusticeps.

Conclusion:

The observed apoptotic environment suggests that pyroptosis may be the dominant pathway through which B. gabonica and D. angusticeps snake venoms trigger thymic epithelial apoptosis following envenomation.

Isoquercitrin induces apoptosis and autophagy in hepatocellular carcinoma cells via AMPK/mTOR/p70S6K signaling pathway

Hepatocellular carcinoma (HCC) is an aggressive malignancy with high rates of metastasis and relapse. Isoquercitrin (ISO), a natural flavonoid present in the Chinese bayberry and other plant species, reportedly exerts notable inhibitory effects on tumor cell proliferation, though the mechanism is unknown. In the present study, we exposed HepG2 and Huh7 human liver cancer cells to ISO and examined the roles of autophagy and apoptosis in ISO-mediated cell death. We found that ISO exposure inhibited cell viability and colony growth, activated apoptotic pathway, and triggered dysregulated autophagy by activating the AMPK/mTOR/p70S6K pathway. Autophagy inhibition using 3-methyladenine (3-MA) or Atg5-targeted siRNA decreased the Bax/Bcl-2 ratio, caspase-3 activation, and PARP cleavage and protected cells against ISO-induced apoptosis. Moreover, autophagy inhibition reversed the upregulation of AMPK phosphorylation and downregulation of mTOR and p70S6K phosphorylation elicited by ISO. By contrast, application of a broad-spectrum caspase inhibitor failed to inhibit autophagy in ISO-treated cells. These data indicate that ISO simultaneously induced apoptosis and autophagy, and abnormal induction of autophagic flux contributed to ISO-triggered caspase-3-dependent apoptosis.

Different Role of Raptor and Rictor in Regulating Rasfonin-Induced Autophagy and Apoptosis in Renal Carcinoma Cells

Both Raptor and Rictor are the key components in the complexes of mammalian target of rapamycin (mTOR), which play a vital role in mediating autophagy. Unlike mTOR, the regulatory role of either Raptor or Rictor in the regulation of autophagic process is relatively less explored. In present study, we found that rasfonin, which isolated from Talaromyces sp. 3656-A1 and was a fungal natural product, activated both caspase-dependent apoptosis and autophagy in ACHN, a renal carcinoma cell line. Knockdown of Raptor decreased both rasfonin-induced autophagic flux and PARP-1 cleavage, and in contrast, Rictor silencing increased apoptosis concomitantly enhancing rasfonin-induced autophagy. Unexpectedly, API-2, which was widely used as an inhibitor of Akt, promoted rasfonin-dependent autophagy in Raptor-depleted but not Rictor-deprived cells. Collectively, these results demonstrated that Raptor and Rictor could play a distinctly regulatory role in rasfonin-enhanced autophagy and apoptosis.

miR-21-5p Suppresses Mitophagy to Alleviate Hyperoxia-Induced Acute Lung Injury by Directly Targeting PGAM5

Hyperoxia-induced acute lung injury (HALI) is a severe side effect of refractory hypoxemia treatment, for which no effective therapeutic strategy is available. Here, we found that the lung miR-21-5p level was significantly decreased in the rats subjected to hyperoxia. Further, we presented evidence that miR-21-5p was a crucial regulator of mitophagy and mitochondrial dysfunction. Moreover, it proved that miR-21-5p regulated hyperoxia-induced mitophagy and mitochondrial dysfunction by directly binding to the target gene PGAM5. In conclusion, for the first time, we found that miR-21-5p could directly suppress mitophagy and mitochondrial damage during HALI formation.

Hexavalent chromium induces renal apoptosis and autophagy via disordering the balance of mitochondrial dynamics in rats

The use of hexavalent chromium (Cr(VI)) in many industrial processes has resulted in serious environmental pollution problems. Cr(VI) causes organ toxicity in animals after ingestion or inhalation. However, the exact mechanism by which Cr(VI) produces kidney damage remains elusive. Herein, we investigated whether Cr(VI)-induced kidney damage is related to the disorder of mitochondrial dynamics. In this study, 28 male rats were divided into four groups and intraperitoneally injected with 0, 2, 4, and 6 mg/kg body weight potassium dichromate for 5 weeks. Experiment included analysis of renal histopathology and ultrastructure, determination of biochemical indicators, and measurement of related protein content. The results showed that Cr(VI) induced kidney injury through promotion of oxidative stress, apoptosis, and disorder of mitochondrial dynamics in a dose-dependent manner. The protein levels of the silent information regulator two ortholog 1 (Sirt1), peroxisome proliferation-activated receptor-g coactivator-1a (PGC-1a), and autophagy-related proteins were significantly decreased after Cr(VI) exposure. These findings suggest that Cr(VI) leads to the disorder of mitochondrial dynamics by inhibiting the Sirt1/PGC-1a pathway, which leads to renal apoptosis and autophagy in rats.

The role of cell signaling in the crosstalk between autophagy and apoptosis in the regulation of tumor cell survival in response to sorafenib and neratinib

The molecular mechanisms by which tumor cells survive or die following therapeutic interventions are complex. There are three broadly defined categories of cell death processes: apoptosis (Type I), autophagic cell death (Type II), and necrosis (Type III). In hematopoietic tumor cells, the majority of toxic stimuli cause these cells to undergo a death process called apoptosis; apoptosis specifically involves the cleavage of DNA into large defined pieces and their subsequent localization in vesicles. Thus, 'pure' apoptosis largely lacks inflammatory potential. In carcinomas, however, the mechanisms by which tumor cells ultimately die are considerably more complex. Although the machinery of apoptosis is engaged by toxic stimuli, other processes such as autophagy ("self-eating") and replicative cell death can lead to observations that do not simplistically correspond to any of the individual Type I-III formalized death categories. The 'hybrid' forms of cell death observed in carcinoma cells result in cellular materials being released into the extracellular space without packaging, which promotes inflammation, potentially leading to the accelerated re-growth of surviving tumor cells by macrophages. Drugs as single agents or in combinations can simultaneously initiate signaling via both apoptotic and autophagic pathways. Based on the tumor type and its oncogene drivers, as well as the drug(s) being used and the duration and intensity of the autophagosome signal, apoptosis and autophagy have the potential to act in concert to kill or alternatively that the actions of either pathway can act to suppress signaling by the other pathway. And, there also is evidence that autophagic flux, by causing lysosomal protease activation, with their subsequent release into the cytosol, can directly mediate killing. This review will discuss the interactive biology between apoptosis and autophagy in carcinoma cells. Finally, the molecular actions of the FDA-approved drugs neratinib and sorafenib, and how they enhance both apoptotic and toxic autophagic processes, alone or in combination with other agents, is discussed in a bench-to-bedside manner.

Salinomycin induces autophagic cell death in salinomycin-sensitive melanoma cells through inhibition of autophagic flux

Several literature has shown that salinomycin (Sal) is able to kill various types of cancer cells through different signaling pathways. However, its effect on melanoma has seldom been reported. We examined the anti-cancer efficacy of Sal in melanoma cell lines, and found six of eight cell lines were sensitive to Sal. Given the fact that the roles of Sal are diverse in different cancer types, we were eager to figure out the mechanism involved in the current study. We noticed the most sensitive line, SK-Mel-19, showed a typical morphological change after Sal treatment. The autophagy inhibitor, 3-MA, could effectively suppress Sal-induced cell death. It could also facilitate the increase of autophagic markers and reduce the turnover of autophagosomes, which resulted in an aberrant autophagic flux. On the other hand, Sal could stimulate endoplasmic reticulum stress and cause an accumulation of dysfunctional mitochondria. We also discovered a potential correlation between LC3B mRNA level and its sensitivity to Sal in 43 clinical melanoma samples. Overall, our results indicated that Sal could have multiple effect on melanoma cells and induce autophagic cell death in certain kinds of cells, which provided a new insight into the chemotherapy for melanoma.

Design, synthesis and anticancer activity of naphthoquinone derivatives

Basis on molecular docking and pharmacophore analysis of naphthoquinone moiety, a total of 23 compounds were designed and synthesised. With the help of reverse targets searching, anti-cancer activity was preliminarily evaluated, most of them are effective against some tumour cells, especially compound 12: 1-(5,8-dihydroxy-1,4-dioxo-1,4-dihydronaphthalen-2-yl)-4-methylpent-3-en-1-yl-4-oxo-4-((4-phenoxyphenyl)amino) butanoate whose IC₅₀ against SGC-7901 was 4.1 ± 2.6 μM. Meanwhile the anticancer mechanism of compound 12 had been investigated by AnnexinV/PI staining, immunofluorescence, Western blot assay and molecular docking. The results indicated that this compound might induce cell apoptosis and cell autophagy through regulating the PI3K signal pathway.

Incorporation of docetaxel and thymoquinone in borage nanoemulsion potentiates their antineoplastic activity in breast cancer cells

Combining more than one anticancer agent in a nanocarrier is beneficial in producing a formula with a low dose and limited adverse side effects. The current study aimed to formulate docetaxel (DTX) and thymoquinone (TQ) in borage oil-based nanoemulsion (B-NE) and evaluate its potential in impeding the growth of breast cancer cells. The formulated B-NE and the combination (DTX + TQ) B-NE were prepared by the ultra-sonication method and physically characterized by the dynamic light scattering techniques. The cytotoxicity analyses of (DTX + TQ) B-NE in MCF-7 and MDA-MB-231 cells were evaluated in vitro by using the SRB assay. Cell death mechanisms were investigated in terms of apoptosis and autophagy pathways by flow cytometry. The optimum mean droplet sizes formulated for blank B-NE and the (DTX + TQ) B-NE were 56.04 ± 4.00 nm and 235.00 ± 10.00 nm, respectively. The determined values of the half-maximal inhibitory concentration (IC₅₀) of mixing one-half amounts of DTX and TQ in B-NE were 1.15 ± 0.097 µM and 0.47 ± 0.091 µM in MCF-7 and MDA-MB-231 cells, respectively, which were similar to the IC₅₀ values of the full amount of free DTX in both tested cell lines. The treatment with (DTX + TQ) B-NE resulted in a synergistic effect on both tested cells. (DTX + TQ) B-NE induced apoptosis that was integrated with the stimulation of autophagy. The produced formulation enhances the DTX efficacy against human breast cancer cells by reducing its effective dose, and thus it could have the potential to minimize the associated toxicity.

The In Vitro and In Vivo Anticancer Properties of Chalcone Flavokawain B through Induction of ROS-Mediated Apoptotic and Autophagic Cell Death in Human Melanoma Cells

Melanoma is the most prevalent type of skin cancer with high mortality rates. This study demonstrates the in vitro and in vivo anticancer properties of chalcone flavokawain B (FKB) induced ROS-mediated apoptosis and autophagy in human melanoma (human epithelial melanoma cell line A375 and/or human skin lymph node derived melanoma cell line A2058) cells. Cell viability was calculated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the expression patterns of various apoptosis, autophagy-associated proteins were determined by Western blot methods. Annexin V was detected by flow cytometry, whereas acidic vesicular organelles (AVOs) and intracellular ROS levels were measured by fluorescence microscopy. The in vivo anticancer properties of FKB were evaluated by xenografting the A375 cells into nude mice. The results convey that FKB inhibited cell viability, B-Raf proto-oncogene, serine/threonine kinase (BRAF)/extracellular signal-regulated kinase (ERK) expression in human melanoma cells. Caspase-3 activation, poly (ADP-ribose) polymerase (PARP) cleavage pathway, and Bcl2 associated X (Bax)/B-cell lymphoma 2 (Bcl-2) dysregulation were involved in the execution of apoptosis. Moreover, FKB-induced autophagy was observed through increased microtubule-associated protein 1A/1B-light chain 3B (LC3-II) accumulation and AVOs formation, which was also associated with an increase in sequestosome 1 (SQSTM1/p62), decreased protein kinase B (AKT)/mammalian target of rapamycin (mTOR) expressions, and dysregulated Beclin-1/Bcl-2 levels. Autophagy inhibitors [3-methyladenine (3-MA)/chloroquine (CQ)] and LC3 silencing suppressed FKB-induced apoptosis by decreasing caspase-3 in melanoma cells. The antioxidant N-acetylcysteine (NAC) diminished FKB-induced apoptotic and autophagic cell death. However, the inhibition of apoptosis decreased FKB-induced autophagy (LC3-I/II). The in vivo study confirmed that FKB inhibited melanoma growth in A375-xenografted nude mice. This study concluded that FKB is critically associated with the execution and generation of ROS-modulated apoptotic and autophagic cell death of melanoma cells. FKB also repressed tumor growth in xenografted nude mice. Therefore, flavokawain B might be a potential anti-tumor agent in human melanoma treatment.

Role of autophagy in nerve cell apoptosis in mice infected with street rabies virus

Rabies is an important zoonotic disease in Iran. Autophagy is a process that maintains homeostasis and can be used as an innate defense mechanism against viruses. Apoptosis is the process of programmed cell death induced by physiological and pathological conditions. The crosstalk of autophagy and apoptosis plays a key role in rabies virus infection. In the current study, NMRI mice intra-cranially received 3-Methyl Adenine (3-MA), rapamycin, street rabies virus (SRABV) and drugs plus SRABV. SRABV and Map1lc3, Beclin-1, Atg5 gene expression were assayed by real-time PCR. Immunohistochemistry was carried out via LC3 protein staining as an autophagy marker, and apoptotic cell death was measured using a TUNEL assay. Map1lc3, Beclin-1 and Atg5 genes expression was significantly increased in drug-plus-SRBV-treated tissues compared to control at 24 hpi. Map1lc3 and Atg5 gene expression showed a slight change in the drugs-plus-virus group compared with the control at 72 hpi. The presence of LC3 in the tissues of the group treated with rapamycin plus SRBV confirmed induction of autophagy, but it was not present in the tissues treated with 3-MA plus SRBV. Our data revealed that apoptosis was induced only in the groups receiving the SRBV or rapamycin or both at 24 hpi. Apoptosis was observed after 72 hours, when the drugs' effect had disappeared in all but the autophagy inhibitor group. Understanding the interaction of SRABV with autophagy pathway genes and its effect on host cell apoptosis may open a new horizon for human intervention and allow a deeper understanding of rabies infections.

Autophagy and Liver Diseases

Autophagy plays an important role in the physiology and pathology of the liver. It is involved in the development of many liver diseases such as α-1-antitrypsin deficiency, chronic hepatitis virus infection, alcoholic liver disease, nonalcoholic fatty liver disease, and liver cancer. Autophagy has thus become a new target for the treatment of liver diseases. How to treat liver diseases by regulating autophagy has been a hot topic.

Mechanisms of sex hormones in autoimmunity: focus on EAE

Sex-related differences in the occurrence of autoimmune diseases is well documented, with females showing a greater propensity to develop these diseases than their male counterparts. Sex hormones, namely dihydrotestosterone and estrogens, have been shown to ameliorate the severity of inflammatory diseases. Immunologically, the beneficial effects of sex hormones have been ascribed to the suppression of effector lymphocyte responses accompanied by immune deviation from pro-inflammatory to anti-inflammatory cytokine production. In this review, we present our view of the mechanisms of sex hormones that contribute to their ability to suppress autoimmune responses with an emphasis on the pathogenesis of experimental autoimmune encephalomyelitis.

Calcitriol inhibits apoptosis via activation of autophagy in hyperosmotic stress stimulated corneal epithelial cells in vivo and in vitro

BACKGROUND

Previously, calcitriol has been demonstrated as a potential therapeutic agent for dry eye, whilst its role on corneal epithelium death remains unclear. This study aims to investigate the relationship between apoptosis and autophagy on dry eye related scenario, as well as the effect of calcitriol and its potential mechanism.

METHODS

In vitro, immortalized human corneal epithelial cells (iHCEC) were cultured in hyperosmotic medium with or without various concentrations of calcitriol and other reagents. In vivo, Wistar rats were applied with benzalkonium chloride to induce dry eye. Then rats were topically treated with calcitriol (10^-6 M) for 14 days. Autophagy flux (LC3B-II and SQSTM1/P62) was examined by western blotting or immunostaining. To test cell apoptosis, western blotting for cleaved caspase-3, Annexin V/PI double staining and TUNEL assay were used. CCK-8 assay was performed to detect the cell viability. Small interfering RNA was used to knock down the expression of vitamin D receptor in iHCECs.

RESULTS

Autophagy activation could protect iHCECs against HS induced apoptosis in vitro, and calcitriol was able to augment autophagy flux via VDR signaling, shown as the remarkably elevated expression of LC3B-II, as well as the declined p62 expression. In vivo results further supported the protective role of calcitriol on corneal epithelium apoptosis through promoting autophagy in dry eye rats.

CONCLUSION

The current study indicated that autophagy was an adaptive change of corneal epithelial cells in response to hyperosmotic stress and calcitriol could prevent cells from apoptosis via further activation of autophagy through VDR pathway.

Antimicrobial and mechanism of antagonistic activity of Bacillus sp. A2 against pathogenic fungus and bacteria: The implication on honey's regulatory mechanism on host's microbiota

Honey is thought to act against microbes and regulates microbiota balance, and this is mainly attributed to the enzymatic production of hydrogen peroxide, high osmolarity, and nonperoxidase factors, for example, lysozyme and botanical sources of nectar, while the effect of honey's probiotic is recently considered. The study of honey as source of beneficial microbes is understudied. The purpose of this study was to screen for the beneficial microorganisms in honey with antagonistic property against important pathogens and the mechanism of antimicrobial activity and thus play a beneficial role as probiotics. The results showed that one out of the fourteen bacterial isolates had antimicrobial activity and was identified as Bacillus Sp. A2 by 16S rRNA sequence and morphology. Antimicrobial activity of the isolate against C. albicans, E. coli, and S. aureus was confirmed by Agar well diffusion and liquid coculture assays, and the propagation of those microbes was significantly inhibited after treatment with the isolate Bacillus sp. A2 (p < .05) in comparison with untreated negative control and positive control (fluconazole, chloramphenicol, L. plantarum). The morphological changes including the distorted shape with indentations and leakages (SEM), damaged cell membrane, and cell wall with the disintegration and attachment of the Bacillus sp. A2 (TEM) in treated C. albicans were observed. Meanwhile, reactive oxygen species accumulation and decreased mitochondrial membrane potential were detected in treated C. albicans. These results revealed that the isolate Bacillus sp. A2 from honey has significant antimicrobial activity (p < .05) against C. albicans in comparison with untreated negative control and positive control L. plantarum, which depends on the accumulation of reactive oxygen species, mitochondrial damage, and the cell apoptosis. We concluded that the Bacillus sp. A2 possess the antimicrobial property, which may contribute to regulation of host's microbiota as a beneficial microbe or probiotic.

Occurrence of Retinal Ganglion Cell Loss via Autophagy and Apoptotic Pathways in an Autoimmune Glaucoma Model

PURPOSE

In glaucoma, an apoptotic death of retinal ganglion cells (RGCs) has been shown. However, little is known about other cell death mechanisms, like autophagy or necrosis. Therefore, we investigated these mechanisms in addition to antibody deposits in an experimental autoimmune glaucoma model.

METHODS

Rats were immunized with a retinal ganglion cell-layer homogenate (RGA), while controls received sodium chloride. Untreated rats served as natїve group. After seven weeks, retinal cross-sections were stained with antibodies against RGCs (Brn-3a), apoptosis (cleaved caspase 2, cleaved caspase 3 as well as caspase 3, 8, and 9), autophagy (LC3BII and LAMP1), and necrosis (RIPK3) followed by cell counts. Autophagy was additionally visualized via transmission electron microscopy on retinal sections. Antibody deposits were also analyzed.

RESULTS

We noted a RGC loss after RGA immunization compared to both control groups. Also, significantly more cleaved caspase 2+ RGCs were observed in RGA animals. More caspase 3 and 8 signals were noted in RGA retinas compared to both controls, while no changes were seen in regard to caspase 9. Furthermore, significantly more cleaved caspase 3+ cells were detected in RGA animals. We noted an increase of LC3BII+ and LAMP1+ autophagic cells in the RGA group, while no alterations were seen regarding necrotic RIPK3+ cells. Autophagic vesicles were observed via transmission electron microscopy. IgG staining revealed significant differences between the RGA group and controls concerning IgG deposits in the ganglion cell layer.

CONCLUSIONS

Due to the novel results from this study, we conclude that IgG antibodies are involved in RGC loss in this model leading to apoptotic and autophagic cell loss. These results could help to develop new therapy strategies for glaucoma patients.

Biological Evaluation of Oxindole Derivative as a Novel Anticancer Agent against Human Kidney Carcinoma Cells

Renal cell carcinoma has emerged as one of the leading causes of cancer-related deaths in the USA. Here, we examined the anticancer profile of oxindole derivatives (SH-859) in human renal cancer cells. Targeting 786-O cells by SH-859 inhibited cell growth and affected the protein kinase B/mechanistic target of rapamycin 1 pathway, which in turn downregulated the expression of glycolytic enzymes, including lactate dehydrogenase A and glucose transporter-1, as well as other signaling proteins. Treatment with SH-859 altered glycolysis, mitochondrial function, and levels of adenosine triphosphate and cellular metabolites. Flow cytometry revealed the induction of apoptosis and G0/G1 cell cycle arrest in renal cancer cells following SH-859 treatment. Induction of autophagy was also confirmed after SH-859 treatment by acridine orange and monodansylcadaverine staining, immunocytochemistry, and Western blot analyses. Finally, SH-859 also inhibited the tumor development in a xenograft model. Thus, SH-859 can serve as a potential molecule for the treatment of human renal carcinoma.

N-acetyl-cysteine in combination with celecoxib inhibits Deoxynivalenol induced skin tumor initiation via induction of autophagic pathways in swiss mice

Deoxynivalenol is a trichothecene mycotoxin which naturally contaminates small grain, cereals intended for human and animal consumption. Investigations for dermal toxicity of DON has been needed and highlighted by WHO. Previous studies on dermal toxicity suggest that DON has DNA damaging potential leading to skin tumor initiation in mice skin. However, considering its toxicological manifestations arising after dermal exposure, strategies for its prevention/protection are barely available in literatute. Collectively, our study demonstrated that N-acetylcysteine (NAC), precursor of glutathione, significantly alters the genotoxic potential of DON. Further NAC in combination with Celecoxib (CXB) inhibits tumor growth by altering antioxidant status and increasing autophagy in DON initiated Swiss mice. Despite the broad spectrum use of CXB, its use is limited by the concerns about its adverse effects on the cardiovascular system. Serum parameters and histology analysis revealed that CXB (2 mg) when applied topically for 24 weeks did not impart any cardiovascular toxicity which could be because skin permeation potential of CXB was quite low when analyzed through HPLC analysis. Although the anticancer effects of CXB and NAC have been studied, however, the combination of NAC and CXB has yet not been explored for any cancer treatment. Therefore our observations provide additional insights into the therapeutic effects of combinatorial treatment of CXB and NAC against skin tumor prevention. This approach might form a novel alternative strategy for skin cancer treatment as well as skin associated toxicities caused by mycotoxins such as DON. This combinatorial approach can overcome the limitations associated with the use of CXB for long term as topical application of the same seems to be safe in comparison to the oral mode of administration.

Dihydroartemisinin Modulates Apoptosis and Autophagy in Multiple Myeloma through the P38/MAPK and Wnt/β-Catenin Signaling Pathways

Dihydroartemisinin (DHA), an active metabolite and derivative of artemisinin, is the most effective antimalarial drug and has strong antitumor activity in various tumor types. It has recently been reported that DHA can induce autophagy and has significant effects on multiple myeloma (MM), but the mechanisms and the relationship between the autophagy and apoptosis induced by DHA remain to be elucidated. Herein, we demonstrated that DHA significantly induces cell death in a dose- and time-dependent manner via the extrinsic and intrinsic apoptosis pathways. Moreover, DHA-induced autophagy, which plays a prodeath role in MM, can regulate canonical apoptosis and vice versa. Furthermore, the P38/MAPK signaling pathway is responsible for decreased autophagy and increased apoptosis. DHA induces autophagy and apoptosis also through the inhibition of the Wnt/β-catenin signaling pathway. In addition, DHA shows a strong effect in a xenograft mouse model. Collectively, these findings reveal that DHA, as an artemisinin-based drug, could be an effective and safe therapeutic agent for MM.

Trimetazidine alleviates hypoxia/reoxygenation-induced apoptosis in neonatal mice cardiomyocytes via up-regulating HMGB1 expression to promote autophagy

Previous studies demonstrated the effect of Trimetazidine (TMZ) on alleviating cardiomyocytes Hypoxia/Reoxygenation (H/R) injuries and the protective effect of autophagy on Ischemia-Reperfusion (I/R) cell injuries. However, whether the protection mechanism of TMZ was also involved in autophagy remained unclear. Our study introduces the role of HMGB1 to examine the regulation of TMZ on autophagy against cardiomyocytes H/R injuries. After cell extraction and identification through anti-α-actin staining, the cardiomyocytes were made hypoxic and reoxygenated, each for 3 h, and then treated with various concentrations of TMZ and transfected with siHMGB1. Cell viability and apoptosis were measured by the MTS method and flow cytometry, respectively. The expressions of autophagy-related factors (LC3-I, LC3-II, Beclin-1) and HMGB1 were detected by Western blot and qPCR. Lactate dehydrogenase (LDH) release was assessed by ELISA kit. The cardiomyocytes were extracted. H/R decreased the cell viability and increased the LDH level and apoptosis of cardiomyocytes. TMZ had no effect on untreated cardiomyocytes, but it reversed the adverse impact of H/R on cardiomyocytes. The expressions of LC3-II, Beclin-1, and HMGB1 and the ratio of LC3-II/LC3-I were increased in H/R-processed cardiomyocytes and further raised by TMZ pretreatment. However, siHMGB1 transfection aggravated the impact of H/R on cardiomyocytes and suppressed the protective effects of TMZ on H/R damaged cardiomyocytes by increasing the LDH level and apoptosis and reducing the viability of cardiomyocytes. Autophagy was inhibited by siHMGB1 in TMZ-pretreated and H/R-processed cardiomyocytes. TMZ protected cardiomyocytes against H/R injuries may through regulating HMGB1 to increase the impact of autophagy.

MiR-506-3p regulates autophagy and proliferation in post-burn skin fibroblasts through post-transcriptionally suppressing Beclin-1 expression

MicroRNAs (miRNAs) is involved in diverse biological processes of cells including dermal fibroblasts that contributed to wound healing and resulted in keloid scarring. MiR-506-3p has been identified as a tumor suppressor or oncogene in fibroblasts of various cancers, while the role of miR-506-3p in regulating functions of post-burn dermal fibroblasts is poorly known. In this study, miR-506-3p was confirmed to be significantly downregulated in burned tissues and heat-stimulated dermal fibroblasts. Expression levels of autophagy-related proteins suggested thermal stimulus promoting the autophagy in dermal fibroblasts. Then, miR-506-3p inhibition enhanced cell proliferation and cell cycle process in dermal fibroblasts after thermal stimulus, whereas overexpression of miR-506-3p showed the opposite effect. Western blot assay showed that inhibition of miR-506-3p resulted in the upregulation of the expression levels of LC3-II, ATG5, and structural protein collagen I, as well as the downregulation of p62. Marker proteins of intermolecular cross-links in collagen synthesis, including hydroxylysylpyridinoline (HP), lysinepyridine (LP), and lysyl hydroxylase 2 (LH2), were increased by miR-506-3p overexpression and decreased by miR-506-3p inhibition. Moreover, transfection with miR-506-3p mimic suppressed the proliferation and autophagy in heat-stimulated dermal fibroblasts in a dose-dependent manner. Subsequently, dual luciferase reporter gene assay demonstrated that Beclin-1 was a direct target of miR-506-3p, and reintroduction of Beclin-1 could antagonize the suppressive effect of miR-506-3p overexpression on fibroblast proliferation, autophagy, and the intermolecular cross-links in collagen synthesis. Taken together, our findings showed that miR-506-3p regulated autophagy and proliferation in post-burn skin fibroblasts through post-transcriptionally suppressing Beclin-1 expression.

SCFAs induce autophagy in intestinal epithelial cells and relieve colitis by stabilizing HIF-1α

Hypoxia-inducible factor-1α (HIF-1α) is a critical regulator of barrier integrity during colonic mucosal injury. Previous works have shown that the absence of autophagy is implicated in the development of inflammatory bowel disease (IBD). Additionally, changes in bacterial profiles in the gut are intimately associated with IBD. Although HIF-1α, autophagy, microbiota, and their metabolites are all involved in the pathogenesis of IBD, their roles are not known. In this study, we investigated the relationship between HIF-1α and autophagy in healthy and inflammatory states using transgenic mice, colitis models, and cell culture models. We confirmed that the absence of intestinal epithelial HIF-1α changed the composition of the intestinal microbes and increased the susceptibility of mice to dextran sodium sulfate (DSS)-induced colitis. In addition, autophagy levels in the intestinal epithelial cells (IECs) were significantly reduced in IEC-specific HIF-1α-deficient (HIF-1α^∆IEC) mice. Moreover, in the cell culture models, butyrate treatment significantly increased autophagy in HT29 cells under normal conditions, whereas butyrate had little effect on autophagy after HIF-1α ablation. Furthermore, in the DSS-induced colitis model, butyrate administration relieved the colonic injury and suppressed inflammation in Cre-/HIF-1α- (HIF-1α^loxP/loxP) mice. However, the butyrate-mediated protection against colonic injury was considerably diminished in the HIF-1α^∆IEC mice. These results show that HIF-1α, autophagy, and intestinal microbes are essential for the maintenance of intestinal homeostasis. Butyrate can alleviate DSS-induced colitis by regulating autophagy via HIF-1α. These insights may have important implications for the development of therapeutic strategies for IBD. KEY MESSAGES: • The absence of intestinal epithelial HIF-1α leads to downregulation of autophagy in mice. • The absence of intestinal epithelial HIF-1α exacerbates DSS-induced colitis. • Short-chain fatty acids (SCFAs) can alleviate DSS-induced colitis by regulating autophagy via HIF-1α.

The Mitochondria: A Target of Polyphenols in the Treatment of Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM) is a constellation of symptoms consisting of ventricular dysfunction and cardiomyocyte disarray in the presence of diabetes. The exact cause of this type of cardiomyopathy is still unknown; however, several processes involving the mitochondria, such as lipid and glucose metabolism, reactive oxygen species (ROS) production, apoptosis, autophagy and mitochondrial biogenesis have been implicated. In addition, polyphenols have been shown to improve the progression of diabetes. In this review, we discuss some of the mechanisms by which polyphenols, particularly resveratrol, play a role in slowing the progression of DCM. The most important intermediates by which polyphenols exert their protective effect include Bcl-2, UCP2, SIRT-1, AMPK and JNK1. Bcl-2 acts to attenuate apoptosis, UCP2 decreases oxidative stress, SIRT-1 increases mitochondrial biogenesis and decreases oxidative stress, AMPK increases autophagy, and JNK1 decreases apoptosis and increases autophagy. Our dissection of these molecular players aims to provide potential therapeutic targets for the treatment of DCM.

Pharmacological Effects of Fasudil on Flap Survival in a Rodent Model

BACKGROUND

Necrosis of the perforator flap is a critical problem. Fasudil, an inhibitor of Rho-associated coiled-coil containing kinase, has antiapoptosis activity and attenuates oxidative stress in many diseases. We characterized the effects of fasudil through intraperitoneal injection on perforator flap survival and identified its possible mechanism.

METHODS AND MATERIALS

Rats were divided into a control group (without surgery), a flap group (only surgery), and a fasudil group (surgery plus fasudil). Perforator flaps were made on the backs of the rats. The expression of vascular endothelial growth factor, the protein kinase B (PKB/Akt), endothelial nitric oxide synthase, Bax, Bcl-2, Beclin-1, P62, and LC3 II/LC3 I was determined by Western blot at day 3 after surgery. Nitric oxide (NO) components, superoxide dismutase, and malondialdehyde were also measured at day 3. The survival rate and laser Doppler perfusion imaging were performed at day 7 after surgery.

RESULT

The group with fasudil treatment exhibited the higher survival rates and angiogenesis levels. Fasudil also induced the activation of Akt/eNOS/NO pathway detected by the Western blot and NO expression kit. Furthermore, Western blot results showed fasudil-attenuated apoptosis through a raised Bcl-2/Bax rate and enhanced autophagy levels through raised beclin-1, decreased p62, and the elevated rate of LC3 II/LC3 I. Finally, fasudil increased superoxide dismutase and decreased malondialdehyde.

CONCLUSIONS

In conclusion, fasudil treatment decreased necrosis of perforator flaps possibly by affecting the Akt/eNOS/NO pathway, attenuating apoptosis and activating autophagy.

Protective Effects of Rapamycin on Trabecular Meshwork Cells in Glucocorticoid-Induced Glaucoma Mice

Glucocorticoid-induced glaucoma (GIG) is a chronic optic neuropathy caused by systemic or topical glucocorticoid (GC) treatment, which could eventually lead to permanent vision loss. To investigate the protective effects of rapamycin (RAP) on the trabecular cells during the development of GIG in mice, the effects of RAP on intraocular pressure (IOP), trabecular ultrastructure, and retinal ganglion cells (RGCs) were examined in C57BL/6J female mice treated with dexamethasone acetate (Dex-Ace). The expression of α-actin in trabecular tissue was detected by immunofluorescence, and the autophagic activity of trabecular cells and the expression of GIG-related myocilin and α-actin were detected by immunoblotting. Our results indicated that Dex-Ace significantly increased IOP at the end of the third week (p < 0.05), while RAP treatment neutralized this elevation of IOP by Dex-Ace. Dex-Ace treatment significantly decreased the RGC numbers (p < 0.05), while synchronous RAP treatment kept the number comparable to control. The outer sheath of elastic fibers became thicker and denser, and the mitochondria of lesions increased in Dex-Ace-treated groups at 4 weeks, while no significant change was observed in the RAP-treated trabecular tissues. Dex-Ace induced myocilin, α-actin, Beclin-1, and LC3-II/LC-I ratio, and lowered p62, while synchronous RAP treatment further activated autophagy and neutralized the induction of myocilin and α-actin. Our studies suggested that RAP protected trabecular meshwork cells by further inducing autophagy way from damages of GC treatment.

Kinetic and protective role of autophagy in manganese-exposed BV-2 cells

Manganese (Mn) plays an important role in many physiological processes. Nevertheless, Mn accumulation in the brain can cause a parkinsonian-like syndrome known as manganism. Unfortunately, the therapeutic options for this disease are scarce and of limited efficacy. For this reason, a great effort is being made to understand the cellular and molecular mechanisms involved in Mn toxicity in neuronal and glial cells. Even though evidence indicates that Mn activates autophagy in microglia, the consequences of this activation in cell death remain unknown. In this study, we demonstrated a key role of reactive oxygen species in Mn-induced damage in microglial cells. These species generated by Mn²⁺ induce lysosomal alterations, LMP, cathepsins release and cell death. Besides, we described for the first time the kinetic of Mn²⁺-induced autophagy in BV-2 microglial cells and its relevance to cell fate. We found that Mn promotes a time-dependent increase in LC3-II and p62 expression levels, suggesting autophagy activation. Possibly, cells trigger autophagy to neutralize the risks associated with lysosomal rupture. In addition, pre-treatment with both Rapamycin and Melatonin enhanced autophagy and retarded Mn²⁺ cytotoxicity. In summary, our results demonstrated that, despite the damage inflicted on a subset of lysosomes, the autophagic pathway plays a protective role in Mn-induced microglial cell death. We propose that 2 h Mn²⁺ exposure will not induce disturbances in the autophagic flux. However, as time passes, the accumulated damage inside the cell could trigger a dysfunction of this mechanism. These findings may represent a valuable contribution to future research concerning manganism therapies.

Anticancer Activity of Novel Plant Extracts and Compounds from Adenosma bracteosum (Bonati) in Human Lung and Liver Cancer Cells

Cancer is the second leading cause of death globally, and despite the advances in drug development, it is still necessary to develop new plant-derived medicines. Compared with using conventional chemical drugs to decrease the side effects induced by chemotherapy, natural herbal medicines have many advantages. The present study aimed to discover the potential cytotoxicity of ethanol extract and its derived fractions (chloroform, ethyl acetate, butanol, and aqueous) of Adenosma bracteosum Bonati. (A. bracteosum) on human large cell lung carcinoma (NCI-H460) and hepatocellular carcinoma (HepG2). Among these fractions, the chloroform showed significant activity in the inhibition of proliferation of both cancerous cells because of the presence of bioactive compounds including xanthomicrol, 5,4'-dihydroxy-6,7,8,3'-tetramethoxyflavone, and ursolic acid which were clearly revealed by nuclear magnetic resonance spectroscopy (1H-NMR, 13C-NMR, Heteronuclear Multiple Bond Coherence, and Heteronuclear Single Quantum Coherence Spectroscopy) analyses. According to the radical scavenging capacity, the 5,4'-dihydroxy-6,7,8,3'-tetramethoxyflavone compound (AB2) exhibited the highest anticancer activity on both NCI-H460 and HepG2 with IC50 values of 4.57 ± 0.32 and 5.67 ± 0.09 µg/mL respectively, followed by the ursolic acid with the lower percent inhibition at 13.05 ± 0.55 and 10.00 ± 0.16 µg/mL, respectively (p < 0.05). Remarkably, the AB2 compound induced to significant increase in the production of reactive oxygen species accompanied by attenuation of mitochondrial membrane potential, thus inducing the activation of caspase-3 activity in both human lung and liver cancer cells. These results suggest that A. bracteosum is a promising source of useful natural products and AB2 offers opportunities to develop the novel anticancer drugs.

SSPH I, a Novel Anti-Cancer Saponin, Inhibits Autophagy and Induces Apoptosis via ROS Accumulation and ERK1/2 Signaling Pathway in Hepatocellular Carcinoma Cells

Introduction

Saponin of Schizocapsa plantaginea Hance I (SSPH I), a novel bioactive phytochemical isolated from the rhizomes of Schizocapsa plantaginea, has been demonstrated to exhibit anti-cancer activity against various tumors in preclinical studies. However, the molecular mechanisms involved in the suppression of hepatocellular carcinoma (HCC) are poorly understood. The present study aimed at analyzing the effects of SSPH I on autophagy and apoptosis in vitro.

Methods

MTT and colony forming assays were used to detect cell viability and cell proliferation. Hoechst 33,258 staining and flow cytometry were used to determine apoptosis and ROS production. The apoptosis and autophagy-related protein expression levels were evaluated via Western blot assay. Characteristics of autophagy and apoptosis were observed by transmission electron microscopy. Lysosomal activity was stained with Lyso-Tracker Red and Magic Red Cathepsin B.

Results

The results showed that SSPH I exhibited potent anti-cancer activity and proliferation in HepG2 and BEL-7402 cells and inhibited HepG2 cells through inhibiting autophagy and promoting apoptosis. The mechanistic study indicated that the inhibition of autophagy of SSPH I was mediated by blocking autophagosome–lysosome fusion. Additionally, we found that SSPH I could mediate the activation of MAPK/ERK1/2 signaling pathway, and the use of NAC (ROS inhibitor) and U0126 (MEK1/2 inhibitor) converted the effect of SSPH I on apoptosis and autophagy in HepG2 cells.

Conclusion

These data suggest that SSPH I induces tumor cells apoptosis and reduces autophagy in vitro by inducing ROS and activating MAPK/ERK1/2 signaling pathway, indicating that SSPH I might be a novel agent for the treatment of HCC.

The preparation of a cold-water soluble polysaccharide from Grifola frondosa and its inhibitory effects on MKN-45 cells

In this study, a novel water soluble polysaccharide (named GFP-4) was extracted from Grifola frondosa at 4 ^oC, and its preliminary structure and inhibitory effects on human gastric carcinoma MKN-45 cells through the Fas/FasL death receptor apoptosis pathway were investigated. High-performance gel permeation chromatography (HPGPC), fourier-transform infrared spectroscopy (FT-IR), and ion chromatography (IC) results showed that GFP-4 was a 1.09 × 10⁶ Da neutral hetero polysaccharide with pyranose rings, and α- and β-type glycosidic linkages that contained galactose, glucose, and mannose at a molar ratio of 1.00:3.45:1.19. MTT results indicated that GFP-4 significantly inhibited the proliferation of MKN-45 cells in a concentration-dependent manner. The H&E staining and Hoechst 33342/PI double staining results showed that GFP-4-treated MKN-45 cells were subjected to underwent typical apoptotic morphologic changes such as nuclear pyknosis, chromatin condensation, and an increase of membrane permeability. Annexin V-FITC/PI double staining, cell cycle analysis, and western blot results revealed the GFP-4 induced MKN-45 cells apoptosis through the Fas/FasL-mediated death receptor pathway with cells arrested at the G0/G1 phase. These data indicate that GFP-4 is a promising candidate for treating gastric cancer and provide a theoretical basis for the future development and utilization of G. frondosa clinically.

Inhibiting autophagy potentiates the antitumor efficacy of Euphorbia royleana for canine mammary gland tumors

Background

Canine mammary gland tumors (cMGTs) are the most common neoplasms in intact female canines and viewed as a suitable model for studying human breast cancers. Euphorbia royleana has been reported to have a variety of antitumor efficacies. We have prepared the crude extracts of E. royleana in ethanol and hexane solvents to evaluate the anti-tumor effects for cMGT in vitro and in vivo.

Results

The results showed that E. royleana could inhibit cell proliferation and colony formation in cMGT cells. The suppression of tumor cell growth resulted from necrosis and cell cycle arrest. Moreover, autophagy appears to play a critical role in E. royleana-mediated cell death by triggering cell apoptosis. The in vivo results also revealed that E. royleana treatment could reduce the size of solid tumors while exhibiting low toxicity in cMGT-bearing nude mice.

Conclusions

The anti-tumor mechanisms of E. royleana were firstly verified to show it would cause autophagic cell death, apoptosis, and cell cycle arrest in canine mammary tumor cells. The in vitro and in vivo findings in the present study revealed E. royleana has potential anticancer effects for the treatment of canine mammary gland tumors.

HIV Nef and Antiretroviral Therapy Have an Inhibitory Effect on Autophagy in Human Astrocytes that May Contribute to HIV-Associated Neurocognitive Disorders

A significant number of people living with HIV (PLWH) develop HIV-associated neurocognitive disorders (HAND) despite highly effective antiretroviral therapy (ART). Dysregulated macroautophagy (autophagy) is implicated in HAND pathogenesis. The viral protein Nef, expressed even with suppressive ART, and certain antiretrovirals affect autophagy in non-CNS cells. Astrocytes, vital for CNS microenvironment homeostasis and neuronal health, require autophagy for their own homeostasis. We hypothesized that extracellular Nef and/or ART impact astrocyte autophagy, thus contributing to HAND. We studied in-bulk and selective autophagic flux in primary human astrocytes treated with extracellular Nef and/or a combination of tenofovir+emtricitabine+raltegravir (ART) using Western blotting, a tandem fluorescent LC3 reporter, and transmission electron microscopy/morphometry. We show that after 24 h treatment, Nef and ART decrease autophagosomes through different mechanisms. While Nef accelerates autophagosome degradation without inducing autophagosome formation, ART inhibits autophagosome formation. Combination Nef+ART further depletes autophagosomes by inducing both abnormalities. Additionally, extracellular Nef and/or ART inhibit lysosomal degradation of p62, indicating Nef and/or ART affect in-bulk and selective autophagy differently. Dysregulation of both autophagic processes is maintained after 7 days of Nef and/or ART treatment. Persistent autophagy dysregulation due to chronic Nef and/or ART exposure may ultimately result in astrocyte and neuronal dysfunction, contributing to HAND.

Chrysosplenol d, a Flavonol from Artemisia annua, Induces ERK1/2-Mediated Apoptosis in Triple Negative Human Breast Cancer Cells

Triple negative human breast cancer (TNBC) is an aggressive cancer subtype with poor prognosis. Besides the better-known artemisinin, Artemisia annua L. contains numerous active compounds not well-studied yet. High-performance liquid chromatography coupled with diode-array and mass spectrometric detection (HPLC-DAD-MS) was used for the analysis of the most abundant compounds of an Artemisia annua extract exhibiting toxicity to MDA-MB-231 TNBC cells. Artemisinin, 6,7-dimethoxycoumarin, arteannuic acid were not toxic to any of the cancer cell lines tested. The flavonols chrysosplenol d and casticin selectively inhibited the viability of the TNBC cell lines, MDA-MB-231, CAL-51, CAL-148, as well as MCF7, A549, MIA PaCa-2, and PC-3. PC-3 prostate cancer cells exhibiting high basal protein kinase B (AKT) and no ERK1/2 activation were relatively resistant, whereas MDA-MB-231 cells with high basal ERK1/2 and low AKT activity were more sensitive to chrysosplenol d treatment. In vivo, chrysosplenol d and casticin inhibited MDA-MB-231 tumor growth on chick chorioallantoic membranes. Both compounds induced mitochondrial membrane potential loss and apoptosis. Chrysosplenol d activated ERK1/2, but not other kinases tested, increased cytosolic reactive oxygen species (ROS) and induced autophagy in MDA-MB-231 cells. Lysosomal aberrations and toxicity could be antagonized by ERK1/2 inhibition. The Artemisia annua flavonols chrysosplenol d and casticin merit exploration as potential anticancer therapeutics.

NMK-BH2, a novel microtubule-depolymerising bis (indolyl)-hydrazide-hydrazone, induces apoptotic and autophagic cell death in cervical cancer cells by binding to tubulin at colchicine - site

BACKGROUND

Microtubules, the key components of the eukaryotic cytoskeleton and mitotic spindle, are one of the most sought-after targets for cancer chemotherapy, especially due to their indispensible role in mitosis. Cervical cancer is a prevalent malignancy among women of developing countries including India. In spite of the remarkable therapeutic advancement, the non-specificity of chemotherapeutic drugs adversely affect the patients' survival and well-being, thus, necessitating the quest for novel indole-based anti-microtubule agent against cervical cancer, with high degree of potency and selectivity.

METHODS

For in vitro studies, we used MTT assay, confocal microscopy, fluorescence microscopy, flow cytometry and Western blot analysis. Study in cell free system was accomplished by spectrophotometry, fluorescence spectroscopy and TEM and computational analysis was done by AutodockTools 1.5.6.

RESULTS

NMK-BH2 exhibited significant and selective anti-proliferative activity against cervical cancer HeLa cells (IC₅₀ = 1.5 μM) over normal cells. It perturbed the cytoskeletal and spindle microtubules of HeLa cells leading to mitotic block and cell death by apoptosis and autophagy. Furthermore, NMK-BH2 targeted the tubulin-microtubule system through fast and strong binding to the αβ-tubulin heterodimers at colchicine-site.

CONCLUSION

This study identifies and characterises NMK-BH2 as a novel anti-microtubule agent and provides insights into its key anti-cancer mechanism through two different cell death pathways: apoptosis and autophagy, which are mutually independent.

GENERAL SIGNIFICANCE

It navigates the potential of the novel bis (indolyl)-hydrazide-hydrazone, NMK-BH2, to serve as lead for development of new generation microtubule-disrupting chemotherapeutic with improved efficacy and remarkable selectivity towards better cure of cervical cancer.

Astragaloside IV enhances GATA-4 mediated myocardial protection effect in hypoxia/reoxygenation injured H9c2 cells

BACKGROUND AND AIM

The transcription factor GATA-4 plays an important role in myocardial protection. Astragaloside IV (Ast-IV) was reported with the effects on improving cardiac function after ischemia. In this study, we explored how Ast-IV interacts with GATA-4 to protect myocardial cells H9c2 against Hypoxia/Reoxygenation (H/R) stress.

METHODS AND RESULTS

H9c2 cells were cultured under the H/R condition. Various cell activity and morphology assays were used to assess the rates of apoptosis and autophagy. In these H/R injured H9c2 cells, increased apoptosis (P < 0.01) and autophagosome number (P < 0.01) were observed, and the addition of Ast-IV ameliorated this tendency. Mechanistically, we used the RT-qPCR and Western blot to evaluate the expressions of various molecules. The results showed that Ast-IV treatment upregulated gene expression of GATA-4 (P < 0.01) and the survival factors (Bcl-2, P < 0.05; p62, P < 0.01), but suppressed apoptosis and autophagy related genes (PARP, Caspase-3, Beclin-1, and LC3-II; All P < 0.01). Furthermore, overexpressing of GATA-4 by its agonist phenylephrine can also protect H/R injured H9c2 cells, and the addition of Ast-IV further enhanced this protection of GATA-4. In contrast, silencing GATA-4 expression abolished the H/R protection of Ast-IV, which demonstrated that the myocardial protection of Ast-IV is mediated by GATA-4. Lastly, along with GATA overexpression, enhanced interactions between Bcl-2 and Beclin-1 were detected by Chromatin immunoprecipitation (P < 0.01).

CONCLUSION

Ast-IV rescued the H/R injury induced apoptosis and autophagy in H9c2 cells. Ast-IV treatment can stimulate the overexpression of GATA-4, and further enhanced the myocardial protection effect of GATA-4.

Role of autophagy in the pathogenesis of rheumatoid arthritis: Latest evidence and therapeutic approaches

Autophagy is considered as an important intracellular mechanism that degrades cytoplasmic components to furnish additional energy. It has cytoprotective effects through the degradation of intracellular pathogens, damaged organelles, and protein aggregates. On the other hand, there are reports of an association between autophagy and autoimmune diseases. Indeed, it has been evident that autophagy is dysregulated in various autoimmune diseases including rheumatoid arthritis (RA). Autophagy is implicated in the maturation survival and proliferation of various immune and non-immune cells, which play pivotal roles in RA pathogenesis. Additionally, autophagy seems to be involved in citrullination and presentation of citrullinated peptides to T lymphocyte cells. Presentation of citrullinated peptides through MHC compartments to the T cells leads to immune response and chronic inflammation. Evidence suggests that autophagy could be implicated in apoptosis resistance of RA fibroblast-like synoviocyte (RA FLS), osteoclastogenesis, and finally severe bone and cartilage destruction. Since autophagy could be an important phenomenon in RA pathogenesis, we summarized the roles of autophagy in citrullination, osteoclastogenesis, RA FLS cells survival, apoptosis resistance of cells, lymphocyte homeostasis and its clinical outcomes in RA disease.

Differential toxicity mechanism of gold nanoparticles in HK-2 renal proximal tubular cells and 786-0 carcinoma cells

Aim: To research the influence and mechanism of gold nanoparticles (AuNPs) with different size for HK-2 cells (kidney normal cells) and 786-0 cells (kidney cancer cells). Materials & methods: HK-2 cells and 786-0 cells were treated with 5 and 200 nm AuNPs at 1 and 10 μg/ml. The cell viability, intracellular reactive oxygen species levels, cell apoptosis, cell autophagy, and related cell signaling pathways were analyzed. Results: In HK-2 cells, AuNPs reduced the activity of Akt and mTOR and upregulated the expression of LC3 II. In 786-0 cells, the activity of p38 was upregulated, which leaded to the increase of caspase 3 and initiated apoptosis. Conclusion: AuNPs of 5 and 200 nm at 10 μg/ml exerted antitumor effect by prompting apoptosis and inhibiting proliferation, while autophagy was activated to protect HK-2 cells from AuNPs-induced cytotoxicity.