Cleavage of Atg3 protein by caspase-8 regulates autophagy during receptor-activated cell death

Diosmetin Promotes Early Embryonic Development in Pigs by Alleviating Oxidative Stress

Diosmetin (DIOS), a natural flavonoid monomer derived from lemons and present in various plants such as spearmint and spider moss, exhibits antioxidant, anti-inflammatory, and antiaging properties. Nonetheless, its impact on early embryonic development in pigs remains unexplored. This study aimed to determine the influence of DIOS supplementation in an in vitro culture (IVC) medium on porcine embryo development and to elucidate the underlying mechanisms. Findings revealed that embryos cultured in IVC medium with 0.1 μM DIOS demonstrated an increased blastocyst formation rate, higher total cell number, reduced LC3B and CASPASE3 levels, elevated Nrf2 levels, decreased ROS, and enhanced GSH and mitochondrial membrane potential at the 4-cell embryonic stage. Additionally, the expression of proapoptotic genes (CAS3, CAS8, and BAX) and autophagy-related genes (BECLIN1, ATG5, LC3B, and P62) was downregulated, whereas the expression of embryonic development-related genes (CDK1 and CDK2), antioxidant-related genes (SOD1 and SOD2), and mitochondrial biogenesis-related genes (NRF2) was upregulated. These findings suggest that DIOS promotes early embryonic development in pigs by mitigating oxidative stress and enhancing mitochondrial function, thereby reducing autophagy and apoptosis levels.

NBR1-mediated autophagic degradation of caspase 8 protects vascular endothelial cells against arsenite-induced apoptotic cell death

Vascular endothelial cells play a critical role in maintaining the health of blood vessels, but dysfunction can lead to cardiovascular diseases. The impact of arsenite exposure on cardiovascular health is a significant concern due to its potential adverse effects. This study aims to explore how NBR1-mediated autophagy in vascular endothelial cells can protect against oxidative stress and apoptosis induced by arsenite. Initially, our observations revealed that arsenite exposure increased oxidative stress and triggered apoptotic cell death in human umbilical vein endothelial cells (HUVECs). However, treatment with the apoptosis inhibitor Z-VAD-FMK notably reduced arsenite-induced apoptosis. Additionally, arsenite activated the autophagy pathway and enhanced autophagic flux in HUVECs. Interestingly, inhibition of autophagy exacerbated arsenite-induced apoptotic cell death. Our findings also demonstrated the importance of autophagy receptor NBR1 in arsenite-induced cytotoxicity, as it facilitated the recruitment of caspase 8 to autophagosomes for degradation. The protective effect of NBR1 against arsenite-induced apoptosis was compromised when autophagy was inhibited using pharmacological inhibitors or through genetic knockdown of essential autophagy genes. Conversely, overexpression of NBR1 facilitated caspase 8 degradation and reduced apoptotic cell death in arsenite-treated HUVECs. In conclusion, our study highlights the vital role of NBR1-mediated autophagic degradation of caspase 8 in safeguarding vascular endothelial cells from arsenite-induced oxidative stress and apoptotic cell death. Targeting this pathway could offer a promising therapeutic approach to mitigate cardiovascular diseases associated with arsenite exposure.

Natural products targeting autophagy and apoptosis in NSCLC: a novel therapeutic strategy

Lung cancer is the leading cause of cancer-related mortality worldwide, with non-small cell lung cancer (NSCLC) being the predominant type. The roles of autophagy and apoptosis in NSCLC present a dual and intricate nature. Additionally, autophagy and apoptosis interconnect through diverse crosstalk molecules. Owing to their multitargeting nature, safety, and efficacy, natural products have emerged as principal sources for NSCLC therapeutic candidates. This review begins with an exploration of the mechanisms of autophagy and apoptosis, proceeds to examine the crosstalk molecules between these processes, and outlines their implications and interactions in NSCLC. Finally, the paper reviews natural products that have been intensively studied against NSCLC targeting autophagy and apoptosis, and summarizes in detail the four most retrieved representative drugs. This paper clarifies good therapeutic effects of natural products in NSCLC by targeting autophagy and apoptosis and aims to promote greater consideration by researchers of natural products as candidates for anti-NSCLC drug discovery.

VPS41-mediated incomplete autophagy aggravates cadmium-induced apoptosis in mouse hepatocytes

Exposure to cadmium (Cd), an environmental heavy metal contaminant, is a serious threat to global health that increases the burden of liver diseases. Autophagy and apoptosis are important in Cd-induced liver injury. However, the regulatory mechanisms involved in the progression of Cd-induced liver damage are poorly understood. Herein, we investigated the role of vacuolar protein sorting 41 (VPS41) in Cd-induced autophagy and apoptosis in hepatocytes. We used targeted VPS41 regulation to elucidate the mechanism of Cd-induced hepatotoxicity. Our data showed that Cd triggered incomplete autophagy by downregulating VPS41, aggravating Cd-induced hepatocyte apoptosis. Mechanistically, Cd-induced VPS41 downregulation interfered with the mTORC1-TFEB/TFE3 axis, leading to an imbalance in autophagy initiation and termination and abnormal activation of autophagy. Moreover, Cd-induced downregulation of VPS41 inhibited autophagosome-lysosome fusion, leading to blocked autophagic flux. This triggers incomplete autophagy, which causes excessive P62 accumulation, accelerating Caspase-9 (CASP9) cleavage. Incomplete autophagy blocks clearance of cleaved CASP9 (CL-CASP9) via the autophagic pathway, promoting apoptosis. Notably, VPS41 overexpression alleviated Cd-induced incomplete autophagy and apoptosis, independent of the homotypic fusion and protein sorting complex. This study provides a new mechanistic understanding of the relationship between autophagy and apoptosis, suggesting that VPS41 is a new therapeutic target for Cd-induced liver damage.

The autophagic protein FYCO1 controls TNFRSF10/TRAIL receptor induced apoptosis and is inactivated by CASP8 (caspase 8)

Apoptosis is a tightly controlled cell death program executed by proteases, the so-called caspases. It plays an important role in tissue homeostasis and is often dysregulated in cancer. Here, we identified FYCO1, a protein that promotes microtubule plus end-directed transport of autophagic and endosomal vesicles as a molecular interaction partner of activated CASP8 (caspase 8). The absence of FYCO1 sensitized cells to basal and TNFSF10/TRAIL-induced apoptosis by receptor accumulation and stabilization of the Death Inducing Signaling Complex (DISC). Loss of FYCO1 resulted in impaired transport of TNFRSF10B/TRAIL-R2/DR5 (TNF receptor superfamily member 10b) to the lysosomes in TNFSF10/TRAIL-stimulated cells. More in detail, we show that FYCO1 interacted via its C-terminal GOLD domain with the CCZ1-MON1A complex, which is necessary for RAB7A activation and for the fusion of autophagosomal/endosomal vesicles with lysosomes. We demonstrated that FYCO1 is a novel and specific CASP8 substrate. The cleavage at aspartate 1306 resulted in the release of the C-terminal GOLD domain, inactivating FYCO1 function, and allowing for the progression of apoptosis. Furthermore, the lack of FYCO1 resulted in a stronger and prolonged formation of the TNFRSF1A/TNF-R1 signaling complex. Thus, FYCO1 limits the ligand-induced and steady-state signaling of TNFR-superfamily members, providing a control mechanism that fine-tunes both apoptotic and inflammatory answers.Abbreviations: AP: affinity purification; CHX: cycloheximide; co-IP: co-immunoprecipitation; CRISPR: clustered regularly interspaced short palindromic repeats; DISC: death-inducing signaling complex; DR: death receptors; doxy: doxycycline; GEF: guanine nucleotide exchange factor; ind: inducible; KD: knockdown; KO: knockout; MS: mass spectrometry; shRNA: short hairpin RNA; siRNA: small interfering RNA; TIP: two-step co-immunoprecipitation; WB: western blot.

A Review on Caspases: Key Regulators of Biological Activities and Apoptosis

Caspases are proteolytic enzymes that belong to the cysteine protease family and play a crucial role in homeostasis and programmed cell death. Caspases have been broadly classified by their known roles in apoptosis (caspase-3, caspase-6, caspase-7, caspase-8, and caspase-9 in mammals) and in inflammation (caspase-1, caspase-4, caspase-5, and caspase-12 in humans, and caspase-1, caspase-11, and caspase-12 in mice). Caspases involved in apoptosis have been subclassified by their mechanism of action as either initiator caspases (caspase-8 and caspase-9) or executioner caspases (caspase-3, caspase-6, and caspase-7). Caspases that participate in apoptosis are inhibited by proteins known as inhibitors of apoptosis (IAPs). In addition to apoptosis, caspases play a role in necroptosis, pyroptosis, and autophagy, which are non-apoptotic cell death processes. Dysregulation of caspases features prominently in many human diseases, including cancer, autoimmunity, and neurodegenerative disorders, and increasing evidence shows that altering caspase activity can confer therapeutic benefits. This review covers the different types of caspases, their functions, and their physiological and biological activities and roles in different organisms.

Ceramides and ceramide synthases in cancer: Focus on apoptosis and autophagy

Different studies corroborate a role for ceramide synthases and their downstream products, ceramides, in modulation of apoptosis and autophagy in the context of cancer. These mechanisms of regulation, however, appear to be context dependent in terms of ceramides' fatty acid chain length, subcellular localization, and the presence or absence of their downstream targets. Our current understanding of the role of ceramide synthases and ceramides in regulation of apoptosis and autophagy could be harnessed to pioneer the development of new treatments to activate or inhibit a single type of ceramide synthase, thereby regulating the apoptosis induction or cross talk of apoptosis and autophagy in cancer cells. Moreover, the apoptotic function of ceramide suggests that ceramide analogues can pave the way for the development of novel cancer treatments. Therefore, in the current review paper we discuss the impact of ceramide synthases and ceramides in regulation of apoptosis and autophagy in context of different types of cancers. We also briefly introduce the latest information on ceramide synthase inhibitors, their application in diseases including cancer therapy, and discuss approaches for drug discovery in the field of ceramide synthase inhibitors. We finally discussed strategies for developing strategies to use lipids and ceramides analysis in biological fluids for developing early biomarkers for cancer.

Chromosome-Level Genome Assembly Provides Insights into the Evolution of the Special Morphology and Behaviour of Lepturacanthus savala

Savalani hairtail Lepturacanthus savala is a widely distributed fish along the Indo-Western Pacific coast, and contributes substantially to trichiurid fishery resources worldwide. In this study, the first chromosome-level genome assembly of L. savala was obtained by PacBio SMRT-Seq, Illumina HiSeq, and Hi-C technologies. The final assembled L. savala genome was 790.02 Mb with contig N50 and scaffold N50 values of 19.01 Mb and 32.77 Mb, respectively. The assembled sequences were anchored to 24 chromosomes by using Hi-C data. Combined with RNA sequencing data, 23,625 protein-coding genes were predicted, of which 96.0% were successfully annotated. In total, 67 gene family expansions and 93 gene family contractions were detected in the L. savala genome. Additionally, 1825 positively selected genes were identified. Based on a comparative genomic analysis, we screened a number of candidate genes associated with the specific morphology, behaviour-related immune system, and DNA repair mechanisms in L. savala. Our results preliminarily revealed mechanisms underlying the special morphological and behavioural characteristics of L. savala from a genomic perspective. Furthermore, this study provides valuable reference data for subsequent molecular ecology studies of L. savala and whole-genome analyses of other trichiurid fishes.

Delineating the twin role of autophagy in lung cancer

Autophagy represents an intracellular defense mechanism equipped within each eukaryotic cells to enable them to cope with variety of physical, chemical, and biological stresses. This mechanism helps to restore the homeostasis and preserve the cellular integrity and function of the cells. In these conditions, such as hypoxia, nutrient deprivation, inhibition of protein synthesis or microbial attack, the process of autophagy is upregulated to maintain cellular homeostasis. The role of autophagy in cancer is an intriguing topic which needs further exploration. This process of autophagy has been many times referred as a double-edged sword in the process of tumorigenesis. In the initial stages, it may act as a tumor suppressor and enable to quench the damaged organelles and harmful molecules generated. In more advanced stages, autophagy has been shown to act as a tumor-promoting system as it may help the cancer cells to cope better with stressful microenvironments. Besides this, autophagy has been associated with development of resistance to anticancer drugs as well as promoting the immune evasion in cancer cells, representing a serious obstacle in cancer treatment and its outcome. Also, autophagy is associated with hallmarks of cancer that may lead to activation of invasion and metastasis. The information on this twin role needs further exploration and deeper understanding of the pathways involved. In this review, we discuss the various aspects of autophagy during tumor development, from early to late stages of tumor growth. Both the protective role of autophagy in preventing tumor growth and the underlying mechanisms adopted with evidence from past studies have been detailed. Further, the role of autophagy in conferring resistance to distinct lung cancer treatment and immune shielding properties has also been discussed. This is essential for further improving on treatment outcome and success rates.

Discovery of a novel dual functional phenylpyrazole-styryl hybrid that induces apoptotic and autophagic cell death in bladder cancer cells

Unpleasant side effects and resistance development remained the Achilles heel of chemotherapy. Since low tumor-selectivity and monotonous effect of chemotherapy are closely related to such bottleneck, targeting tumor-selective multi-functional anticancer agents may be an ideal strategy in the search of new safer drugs. Herein, we report the discovery of compound 21, a nitro-substituted 1,5-diphenyl-3-styryl-1H-pyrazole that possesses dual functional characteristics. The 2D- and 3D-culture-based studies revealed that 21 not only could induce ROS-independent apoptotic and EGFR/AKT/mTOR-mediated autophagic cell deaths in EJ28 cells simultaneously but also has the ability in inducing cell death at both proliferating and quiescent zones of EJ28 spheroids. The molecular modelling analysis showed that 21 possesses EGFR targeting capability as it forms stable interactions in the EGFR active site. Together with its good safety profile in the zebrafish-based model, the present study showed that 21 is promising and may lead to the discovery of tumor-selective multi-functional anti-cancer agents.

BmCaspase-8-like regulates autophagy by suppressing BmDREDD-mediated cleavage of BmATG6

Autophagy plays an important role in tissue remodeling during insect development. The interplay between autophagy-related (ATG) proteins and caspases regulates the autophagic activity of ATGs, thereby modulating the process of autophagy. Our previous study characterized BmCaspase-8-like (BmCasp8L) as a caspase suppressor that inhibits apoptosis and immune signaling by suppressing the activation of death-related ced-3/Nedd2-like caspase (DREDD), a caspase-8 homolog in silkworm. In this study, we explored the regulatory role of BmCasp8L in autophagy. We found that the expression of Bmcasp8l increased from the late spinning stage to the pupa stage in the posterior silk gland (PSG), correlating with the expression patterns of Bmatg8 and Bmatg6. RNA interference-mediated downregulation of BmCasp8L expression significantly decreased starvation-induced autophagic influx as determined by the levels of BmATG8-phosphatidylethanolamine and the percentage of cells displaying punctate enhanced green fluorescent protein-BmATG8. Conversely, the overexpression of BmCasp8L significantly increased autophagic influx. We also found that BmCasp8L underwent autophagic degradation induced by starvation and that it was colocalized with BmATG8. Lastly, we demonstrated that BmDREDD attenuated autophagy and BmCasp8L suppressed BmDREDD-mediated cleavage of BmATG6. Taken together, our results demonstrated that BmCasp8L is a novel proautophagic molecule which suppresses BmDREDD-mediated cleavage of BmATG6 and is a target for autophagy.

Autophagic Molecular Alterations in the Mouse Cerebellum Experimental Autoimmune Encephalomyelitis Model Following Treatment with Cannabidiol and Fluoxetine

The crosstalk between autophagy and apoptosis is one of the most important processes involved in the cell program death, and several mechanisms including oligodendrocyte apoptosis and autophagy play significant roles in activating macrophages, microglial cells, and finally demyelination in neurodegenerative disease. The antidepressants and anti-apoptotic mechanisms of fluoxetine (FLX) and cannabidiol (CBD) commence an autophagic event that can effectively repair myelin. This study aimed to investigate the effect of those reagents on the rate of demyelination in the cerebellum, an important site for white matter in a mouse model of experimental autoimmune encephalomyelitis (EAE). EAE was induced in twenty four adult female C57Bl/6 mice were inducted the EAE model; FLX treatment which was performed (10 mg/kg/IP) and CBD; were treated (5 mg/kg/IP); and their cerebellum was used for Western blotting, real-time PCR to autophagic markers of LC3II, Beclin-1, and apoptotic markers Bax and Bcl2 evaluation and Luxol Fast Blue staining to the assessment of demyelination. The level of autophagic markers was expressively elevated (P < 0.01) but the pro-apoptotic markers and Bax/Bcl2 ratio were reduced (P < 0.05). Luxol Fast Blue staining confirmed the noteworthy diminution of demyelination in treatment groups (P < 0.001). This finding clarified that FLX and CBD ameliorate the severity of the EAE model. Combinatory treatments of these two agents are suggested for future investigations.

Effects of Au@Ag core-shell nanostructure with alginate coating on male reproductive system in mice

Despite the widespread use of silver nanoparticles (NPs), these NPs can accumulate and have toxic effects on various organs. However, the effects of silver nanostructures (Ag-NS) with alginate coating on the male reproductive system have not been studied. Therefore, this study aimed to investigate the impacts of this NS on sperm function and testicular structure. After the synthesis and characterization of Ag-NS, the animals were divided into five groups (n = 8), including one control group, two sham groups (received 1.5 mg/kg/day alginate solution for 14 and 35 days), and two treatment groups (received Ag-NS at the same dose and time). Following injections, sperm parameters, apoptosis, and autophagy were analyzed by the TUNEL assay and measurement of the mRNA expression of Bax, Bcl-2, caspase-3, LC3, and Beclin-1. Fertilization rate was assessed by in vitro fertilization (IVF), and testicular structure was analyzed using the TUNEL assay and hematoxylin and eosin (H&E) staining. The results showed that the NS was rod-shaped, had a size of about 60 nm, and could reduce sperm function and fertility. Gene expression results demonstrated an increase in the apoptotic markers and a decrease in autophagy markers, indicating apoptotic cell death. Moreover, Ag-NS invaded testicular tissues, especially in the chronic phase (35 days), resulting in tissue alteration and epithelium disintegration. The results suggest that sperm parameters and fertility were affected. In addition, NS has negative influences on testicular tissues, causing infertility in men exposed to these NS.

Interlacing the relevance of caspase activation in the onset and progression of Alzheimer's disease

Caspases, a family of cysteine proteases is a renowned regulator of apoptosis. Members of this family are responsible for the proteolytic dismantling of numerous cellular structures. Apart from apoptosis, caspases remarkably contribute to a diverse range of molecular processes. Being the imperative members of several cellular cascades their abnormal activation/deactivation has severe implications and also leads to various diseased conditions. Similar aberrant activation of caspases is one of the several causes of neuropathologies associated with Alzheimer's disease (AD), a form of dementia severely affecting neuropsychiatric and cognitive functions. Emerging studies are providing deeper insights into the mechanisms of caspase action in the progression of AD. Current article is an attempt to review these studies and present the action mechanisms of different mammalian caspases in the advancement of AD associated neuropathologies.

Research Progress on Autophagy Regulation by Active Ingredients of Traditional Chinese Medicine in the Treatment of Acute Lung Injury

Autophagy is a highly conserved process that maintains cell stability in eukaryotes, participates in the turnover of intracellular substances to maintain cell function, helps to resist pathogen invasion, and improves cell tolerance to environmental changes. Autophagy has been observed in many diseases, and the symptoms of these diseases are significantly improved by regulating autophagy. Autophagy is also involved in the development of lung diseases. Studies have shown that autophagy may play a beneficial or harmful role in acute lung injury (ALI), and ALI has been treated with traditional Chinese medicine designed to promote or inhibit autophagy. In this paper, the molecular mechanism and common pathways regulating autophagy and the relationship between autophagy and ALI are introduced, and the active ingredients of traditional Chinese medicine that improve ALI symptoms by regulating autophagy are summarized.

CASP4 and CASP8 as newly defined autophagy-pyroptosis-related genes associated with clinical and prognostic features of renal cell carcinoma

Objective

The rapid discoveries of autophagy and pyroptosis have opened new avenues for treating renal cell carcinoma (RCC). The objective was to identify potential autophagy-pyroptosis-related drug targets and plausible prognostic biomarkers crucial for disease detection.

Materials and Methods

Gene expression data were downloaded from Gene Expression Omnibus (GSE168845), and autophagy-pyroptosis-related differentially expressed genes (DEGs) were identified. The prognostic values of DEGs were assessed using differential expression analysis and Kaplan-Meier curves, a prognostic nomogram was constructed using the DEG data, and the correlation between DEGs and infiltrating immune cells was evaluated. Additionally, quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC) were carried out to verify the expression levels of DEGs.

Results

CASP4 and CASP8 were identified as RCC-associated autophagy-pyroptosis-related genes, and CASP4 and CASP8 were found to be highly expressed in RCC tumor tissues. High expression of CASP4 and CASP8 was associated with higher pathological staging and poorer prognosis, whereas a prognostic nomogram constructed based on CASP4 and CASP8 could better predict RCC patient survival rates. Additionally, increased expression of CASP4 and CASP8 was highly correlated with the expression levels of multiple infiltrating immune cell types. Moreover, qRT-PCR and IHC validated the increased expression of CASP4 and CASP8 in RCC.

Conclusion

CASP4 and CASP8 were autophagy-pyroptosis-related genes associated with immunotherapy in RCC. CASP4 and CASP8 were identified as potential targets and effective prognostic biomarkers for RCC.

Caspase-8 is required for HSV-1-induced apoptosis and promotes effective viral particle release via autophagy inhibition

Regulated cell death (RCD) plays an important role in the progression of viral replication and particle release in cells infected by herpes simplex virus-1 (HSV-1). However, the kind of RCD (apoptosis, necroptosis, others) and the resulting cytopathic effect of HSV-1 depends on the cell type and the species. In this study, we further investigated the molecular mechanisms of apoptosis induced by HSV-1. Although a role of caspase-8 has previously been suggested, we now clearly show that caspase-8 is required for HSV-1-induced apoptosis in a FADD-/death receptor-independent manner in both mouse embryo fibroblasts (MEF) and human monocytes (U937). While wild-type (wt) MEFs and U937 cells exhibited increased caspase-8 and caspase-3 activation and apoptosis after HSV-1 infection, respective caspase-8-deficient (caspase-8−/−) cells were largely impeded in any of these effects. Unexpectedly, caspase-8−/− MEF and U937 cells also showed less virus particle release associated with increased autophagy as evidenced by higher Beclin-1 and lower p62/SQSTM1 levels and increased LC3-I to LC3-II conversion. Confocal and electron microscopy revealed that HSV-1 stimulated a strong perinuclear multivesicular body response, resembling increased autophagy in caspase-8−/− cells, entrapping virions in cellular endosomes. Pharmacological inhibition of autophagy by wortmannin restored the ability of caspase-8−/− cells to release viral particles in similar amounts as in wt cells. Altogether our results support a non-canonical role of caspase-8 in both HSV-1-induced apoptosis and viral particle release through autophagic regulation.

Targeting TRAIL Death Receptors in Triple-Negative Breast Cancers: Challenges and Strategies for Cancer Therapy

The tumor necrosis factor (TNF) superfamily member TNF-related apoptosis-inducing ligand (TRAIL) induces apoptosis in cancer cells via death receptor (DR) activation with little toxicity to normal cells or tissues. The selectivity for activating apoptosis in cancer cells confers an ideal therapeutic characteristic to TRAIL, which has led to the development and clinical testing of many DR agonists. However, TRAIL/DR targeting therapies have been widely ineffective in clinical trials of various malignancies for reasons that remain poorly understood. Triple negative breast cancer (TNBC) has the worst prognosis among breast cancers. Targeting the TRAIL DR pathway has shown notable efficacy in a subset of TNBC in preclinical models but again has not shown appreciable activity in clinical trials. In this review, we will discuss the signaling components and mechanisms governing TRAIL pathway activation and clinical trial findings discussed with a focus on TNBC. Challenges and potential solutions for using DR agonists in the clinic are also discussed, including consideration of the pharmacokinetic and pharmacodynamic properties of DR agonists, patient selection by predictive biomarkers, and potential combination therapies. Moreover, recent findings on the impact of TRAIL treatment on the immune response, as well as novel strategies to address those challenges, are discussed.

The crosstalk among autophagy, apoptosis, and pyroptosis in cardiovascular disease

In recent years, the mechanism of cell death has become a hotspot in research on the pathogenesis and treatment of cardiovascular disease (CVD). Different cell death modes, including autophagy, apoptosis, and pyroptosis, are mosaic with each other and collaboratively regulate the process of CVD. This review summarizes the interaction and crosstalk of key pathways or proteins which play a critical role in the entire process of CVD and explores the specific mechanisms. Furthermore, this paper assesses the interrelationships among these three cell deaths and reviews how they regulate the pathogenesis of CVD. By understanding how these three cell death modes go together we can learn about the pathogenesis of CVD, which will enable us to identify new targets for preventing, controlling, and treating CVD. It will not only reduce mortality but also improve the quality of life.

Impaired autophagy with augmented apoptosis in a Th1/Th2-imbalanced placental micromilieu is associated with spontaneous preterm birth

Background: Despite decades of research, the pathogenesis of spontaneous preterm birth (PTB) remains largely unknown. Limited currently available data on PTB pathogenesis are based on rodent models, which do not accurately reflect the complexity of the human placenta across gestation. While much study has focused on placental infection and inflammation associated with PTB, two key potentially important cellular events in the placenta-apoptosis and autophagy-remained less explored. Understanding the role of these processes in the human placenta may unravel currently ill-understood processes in the pathomechanism of PTB. Methods: To address this necessity, we conducted qRT-PCR and ELISA assays on placental villous tissue from 20 spontaneous preterm and 20 term deliveries, to assess the inter-relationships between inflammation, apoptosis, and autophagy in villous tissue in order to clarify their roles in the pathogenesis of PTB. Results: We found disrupted balance between pro-apoptotic BAX and anti-apoptotic BCL2 gene/protein expression in preterm placenta, which was associated with significant reduction of BCL2 and increase of BAX proteins along with upregulation of active CASP3 and CASP8 suggesting augmented apoptosis in PTB. In addition, we detected impaired autophagy in the same samples, evidenced by significant accumulation of autophagosome cargo protein p62/SQSTM1 in the preterm villous placentas, which was associated with simultaneous downregulation of an essential autophagy gene ATG7 and upregulation of Ca2+-activated cysteine protease CAPN1. Placental aggregation of p62 was inversely correlated with newborn birth weight, suggesting a potential link between placental autophagy impairment and fetal development. These two aberrations were detected in a micromilieu where the genes of the Th2 cytokines IL10 and IL13 were downregulated, suggesting an alteration in the Th1/Th2 immune balance in the preterm placenta. Conclusion: Taken together, our observations suggest that impaired autophagy and augmented apoptosis in a Th1/Th2 imbalanced placental micro-environment may be associated with the pathogenesis of spontaneous PTB.

The cross-talk of autophagy and apoptosis in breast carcinoma: implications for novel therapies?

Breast cancer is still the most common cancer in women worldwide. Resistance to drugs and recurrence of the disease are two leading causes of failure in treatment. For a more efficient treatment of patients, the development of novel therapeutic regimes is needed. Recent studies indicate that modulation of autophagy in concert with apoptosis induction may provide a promising novel strategy in breast cancer treatment. Apoptosis and autophagy are two tightly regulated distinct cellular processes. To maintain tissue homeostasis abnormal cells are disposed largely by means of apoptosis. Autophagy, however, contributes to tissue homeostasis and cell fitness by scavenging of damaged organelles, lipids, proteins, and DNA. Defects in autophagy promote tumorigenesis, whereas upon tumor formation rapidly proliferating cancer cells may rely on autophagy to survive. Given that evasion of apoptosis is one of the characteristic hallmarks of cancer cells, inhibiting autophagy and promoting apoptosis can negatively influence cancer cell survival and increase cell death. Hence, combination of antiautophagic agents with the enhancement of apoptosis may restore apoptosis and provide a therapeutic advantage against breast cancer. In this review, we discuss the cross-talk of autophagy and apoptosis and the diverse facets of autophagy in breast cancer cells leading to novel models for more effective therapeutic strategies.

Direct cleavage of caspase-8 by herpes simplex virus 1 tegument protein US11

The HSV-1 tegument protein Us11 counteracts the antiviral defense mechanisms by precluding the host protein shutoff. Previous works demonstrated that Us11 prevents heat-and staurosporine-induced apoptosis and inhibits autophagy. Therefore, in the present study, we investigated the hypothesis that HSV-1, through Us11, could recruit caspase-8, a key enzyme regulating programmed cell death. We first show that HSV-1 promotes the accumulation of caspase-8-p18 active fragments in both semi permissive THP-1 cells and fully permissive HEp-2 cells to HSV-1 replication. Using a recombinant virus R3630 (ΔUs11/ΔUs12) and a plasmid encoding Us11-recombinant protein we have proven that Us11 promotes p18 accumulation, which does not trigger the apoptotic signaling. Additional, in an in vitro model, we demonstrated that Us11-recombinant protein induces caspase-8-p18 cleavage by physically interacting with the caspase-8 recombinant protein. Finally, we found that, during HSV-1 replication, activated-caspase-8 cleaves Atg3 protein to potentially block autophagy and support its replication.

Assessment of In Vitro Immunostimulatory Activity of an Adjuvanted Whole-Cell Inactivated Neisseria gonorrhoeae Microparticle Vaccine Formulation

The emergence of drug-resistant gonorrhea infections worldwide combined with the lack of a vaccine is alarming. We prepared a novel microparticulate (MP) vaccine formulation using whole-cell inactivated Neisseria gonorrhoeae as the vaccine antigen, with Alum and AddaVax™ as vaccine adjuvants. The adjuvanted vaccine MP formulation was assessed for in vitro immunostimulatory activity, autophagy, and antigen presentation ability. The data shows that the adjuvanted gonococci vaccine MP enhanced autophagy induction in antigen presenting cells (APCs) compared to gonococci vaccine MP without adjuvants, which is important for enhancing antigen presentation. In addition, the adjuvanted vaccine formulation increased the surface expression of antigen presenting molecules MHCI and MHCII as well as co-stimulatory molecules CD40 and CD86 on the surface of dendritic cells. In addition, the gonococci vaccine microparticles at lower doses did not significantly increase the expression of the death receptor CD95 in APCs, which when elevated leads to suboptimal antigen presentation and reduced immune responses. The adjuvanted whole-cell inactivated gonococci microparticle vaccine formulation enhanced antigen uptake, processing, and antigen presentation.

Life and Death Decisions-The Many Faces of Autophagy in Cell Survival and Cell Death

Autophagy is a process conserved from yeast to humans. Since the discovery of autophagy, its physiological role in cell survival and cell death has been intensively investigated. The inherent ability of the autophagy machinery to sequester, deliver, and degrade cytoplasmic components enables autophagy to participate in cell survival and cell death in multiple ways. The primary role of autophagy is to send cytoplasmic components to the vacuole or lysosomes for degradation. By fine-tuning autophagy, the cell regulates the removal and recycling of cytoplasmic components in response to various stress or signals. Recent research has shown the implications of the autophagy machinery in other pathways independent of lysosomal degradation, expanding the pro-survival role of autophagy. Autophagy also facilitates certain forms of regulated cell death. In addition, there is complex crosstalk between autophagy and regulated cell death pathways, with a number of genes shared between them, further suggesting a deeper connection between autophagy and cell death. Finally, the mitochondrion presents an example where the cell utilizes autophagy to strike a balance between cell survival and cell death. In this review, we consider the current knowledge on the physiological role of autophagy as well as its regulation and discuss the multiple functions of autophagy in cell survival and cell death.

The DNA Double-Strand Break Repair in Glioma: Molecular Players and Therapeutic Strategies

Gliomas are the most frequent type of tumor in the central nervous system, which exhibit properties that make their treatment difficult, such as cellular infiltration, heterogeneity, and the presence of stem-like cells responsible for tumor recurrence. The response of this type of tumor to chemoradiotherapy is poor, possibly due to a higher repair activity of the genetic material, among other causes. The DNA double-strand breaks are an important type of lesion to the genetic material, which have the potential to trigger processes of cell death or cause gene aberrations that could promote tumorigenesis. This review describes how the different cellular elements regulate the formation of DNA double-strand breaks and their repair in gliomas, discussing the therapeutic potential of the induction of this type of lesion and the suppression of its repair as a control mechanism of brain tumorigenesis.

Wheat Germ Spermidine and Clove Eugenol in Combination Stimulate Autophagy In Vitro Showing Potential in Supporting the Immune System against Viral Infections

Impaired autophagy, responsible for increased inflammation, constitutes a risk factor for the more severe COVID-19 outcomes. Spermidine (SPD) is a known autophagy modulator and supplementation for COVID-19 risk groups (including the elderly) is recommended. However, information on the modulatory effects of eugenol (EUG) is scarce. Therefore, the effects of SPD and EUG, both singularly and in combination, on autophagy were investigated using different cell lines (HBEpiC, SHSY5Y, HUVEC, Caco-2, L929 and U937). SPD (0.3 mM), EUG (0.2 mM) and 0.3 mM SPD + 0.2 mM EUG, significantly increased autophagy using the hallmark measure of LC3-II protein accumulation in the cell lines without cytotoxic effects. Using Caco-2 cells as a model, several crucial autophagy proteins were upregulated at all stages of autophagic flux in response to the treatments. This effect was verified by the activation/differentiation and migration of U937 monocytes in a three-dimensional reconstituted intestinal model (Caco-2, L929 and U937 cells). Comparable benefits of SPD, EUG and SPD + EUG in inducing autophagy were shown by the protection of Caco-2 and L929 cells against lipopolysaccharide-induced inflammation. SPD + EUG is an innovative dual therapy capable of stimulating autophagy and reducing inflammation in vitro and could show promise for COVID-19 risk groups.

Metabolomics analysis highlights Yashtimadhu (Glycyrrhiza glabra L.)-mediated neuroprotection in a rotenone-induced cellular model of Parkinson's disease by restoring the mTORC1-AMPK1 axis in autophagic regulation

Parkinson's disease (PD) is an age-associated progressive neurodegenerative movement disorder, and its management strategies are known to cause complications with prolonged usage. We aimed to explore the neuroprotective mechanism of the Indian traditional medicine Yashtimadhu, prepared from the dried roots of Glycyrrhiza glabra L. (licorice) in the rotenone-induced cellular model of PD. Retinoic acid-differentiated IMR-32 cells were treated with rotenone (PD model) and Yashtimadhu extract. Mass spectrometry-based untargeted and targeted metabolomic profiling was carried out to discover altered metabolites. The untargeted metabolomics analysis highlighted the rotenone-induced dysregulation and Yashtimadhu-mediated restoration of metabolites involved in the metabolism of nucleic acids, amino acids, lipids, and citric acid cycle. Targeted validation of citric acid cycle metabolites showed decreased α-ketoglutarate and succinate with rotenone treatment and rescued by Yashtimadhu co-treatment. The dysregulation of the citric acid cycle by rotenone-induced energetic stress via dysregulation of the mTORC1-AMPK1 axis was prevented by Yashtimadhu. Yashtimadhu co-treatment restored rotenone-induced ATG7-dependent autophagy and eventually caspases-mediated cell death. Our analysis links the metabolic alterations modulating energy stress and autophagy, which underlies the Yashtimadhu-mediated neuroprotection in the rotenone-induced cellular model of PD.

Synergistic inhibition of the growth of MDA‑MB‑231 cells in triple‑negative breast cancer by salinomycin combined with 17‑AAG and its mechanism

Salinomycin (SAL), a typical ion carrier antibiotic, inhibits tumor growth and metastasis by inducing apoptosis or autophagy in cancer or cancer stem cells and thus overcomes drug resistance. 17-allylamino-17-demethoxygeldanamycin (17-AAG), a heat shock protein Hsp90 competitive inhibitor, also has a role in inhibiting tumor development. However, their combination on the growth of breast cancer cells and its specific mechanism remains to be elucidated. The present study tested the influence of SAL and 17-AAG on cell growth, apoptosis and autophagy by MTT assays, Annexin V-FITC and propidium iodide double staining assay and immunoelectron microscopy. The influence of SAL and 17-AAG on proteomics was investigated by isobaric tag for relative and absolute quantitation. It was found that SAL combined with 17-AAG synergistically inhibited the cell growth and induced the apoptosis in a concentration-dependent manner, with the expression of caspase 3 and Bcl-2 were decreased while the expression of Bax was increased. In addition, SAL combined with 17-AAG inhibited autophagy, with the expression of microtubule-associated protein 1 light chain 3, Beclin1, p62 being decreased. Mechanistically, SAL combined with 17-AAG synergistically inhibited the reactive oxygen species/JNK signaling pathway. In conclusion, SAL combined with 17-AAG had a synergistic inhibitory effect on cell growth of breast cancer via inducing apoptosis and inhibiting autophagy. The present study might provide a new strategy for potential clinical application of SAL as a new anti-tumor drug especially as a drug combination with other molecular targeting therapeutics.

Zearalenone Induces Apoptosis and Autophagy in a Spermatogonia Cell Line

Zearalenone (ZEN), a widely known mycotoxin, is mainly produced by various Fusarium species, and it is a potent estrogenic metabolite that affects reproductive health in livestock and humans. In this study, the molecular mechanisms of toxicity and cell damage induced by ZEN in GC-1 spermatogonia (spg) cells were evaluated. Our results showed that cell viability decreased and apoptosis increased in a dose-dependent manner when GC-1 spg cells were exposed to ZEN. In addition, the key proteins involved in apoptosis, cleaved caspase-3 and -8, BAD, BAX, and phosphorylation of p53 and ERK1/2, were significantly increased in ZEN-exposed GC-1 spg cells for 24 h, and cytochrome c was released from mitochondria by ZEN. Interestingly, ZEN also triggered autophagy in GC-1 spg cells. The expression levels of the autophagy-related genes Atg5, Atg3, Beclin 1, LC3, Ulk1, Bnip 3, and p62 were significantly higher in ZEN-treated GC-1 spg cells, and the protein levels of both LC3A/B and Atg12 were remarkably increased in a dose-dependent manner in ZEN-exposed GC-1 spg cells compared to the control. In addition, immunostaining results showed that ZEN-treated groups showed a remarkable increase in LC 3A/B positive puncta as compared to the control in a dose-dependent manner based on confocal microscopy analysis in GC-1 spg cells. Our findings suggest that ZEN has toxic effects on tGC-1 spg cells and induces both apoptosis and autophagy.

Shedding New Light on Methylmercury-induced Neurotoxicity Through the Crosstalk Between Autophagy and Apoptosis

Methylmercury (MeHg) is a bio-accumulative global environmental contaminant present in fish and seafood. MeHg accumulates in the aquatic environment and eventually reaches the human system via the food chain by bio-magnification. The central nervous system is the primary target of toxicity and is particularly vulnerable during development. It is well documented that developmental MeHg exposure can lead to neurological alterations, including cognitive and motor dysfunction. Apoptosis is a primary characteristic of MeHg-induced neurotoxicity, and may be regulated by autophagic activity. However, mechanisms mediating the interaction between apoptosis and autophagy remains to be explored. Autophagy is an adaptive response under stressful conditions, and the basal level of autophagy ensures the physiological turnover of old and damaged organelles. Autophagy can regulate cell fate through different crosstalk signaling pathways. A complex interplay between autophagy and apoptosis determines the degree of apoptosis and the progression of MeHg-induced neurotoxicity as demonstrated by pre-clinical models and clinical trials. This review summarizes recent advances in the roles of autophagy and apoptosis in MeHg neurotoxicity and thoroughly explores the relationship between them. The autophagic pathway may be a potential therapeutic target in MeHg neurotoxicity through modulation of apoptosis.

Development of a model to predict the prognosis of esophageal carcinoma based on autophagy-related genes

Aim: To identify a potential prognostic signature of esophageal carcinoma based on autophagy-related genes (ARGs). Methods: RNA sequencing and clinical data were downloaded from the Cancer Genome Atlas. Significantly different ARGs were identified by Wilcoxon signed-rank test. A prognostic model was established employing Cox regression analysis. The model was evaluated by receiver operating characteristic and Kaplan-Meier curve. Results: A total of 28 significantly different ARGs were identified. Seven ARGs were screened to construct the prognostic model. The efficacy of the model was verified. A nomogram also validated the role of risk score in predicting prognosis. Enrichment analyses showed the possible underlying mechanisms. Conclusion: The seven-ARGs prognostic model was validated to be promising for predicting the prognosis of patients with esophageal carcinoma.

The complex interplay between autophagy and cell death pathways

Autophagy is a universal cellular homeostatic process, required for the clearance of dysfunctional macromolecules or organelles. This self-digestion mechanism modulates cell survival, either directly by targeting cell death players, or indirectly by maintaining cellular balance and bioenergetics. Nevertheless, under acute or accumulated stress, autophagy can also contribute to promote different modes of cell death, either through highly regulated signalling events, or in a more uncontrolled inflammatory manner. Conversely, apoptotic or necroptotic factors have also been implicated in the regulation of autophagy, while specific factors regulate both processes. Here, we survey both earlier and recent findings, highlighting the intricate interaction of autophagic and cell death pathways. We, Furthermore, discuss paradigms, where this cross-talk is disrupted, in the context of disease.

The non-apoptotic function of Caspase-8 in negatively regulating the CDK9-mediated Ser2 phosphorylation of RNA polymerase II in cervical cancer

Cervical cancer is the fourth most frequently diagnosed and fatal gynecological cancer. 15-61% of all cases metastasize and develop chemoresistance, reducing the 5-year survival of cervical cancer patients to as low as 17%. Therefore, unraveling the mechanisms contributing to metastasis is critical in developing better-targeted therapies against it. Here, we have identified a novel mechanism where nuclear Caspase-8 directly interacts with and inhibits the activity of CDK9, thereby modulating RNAPII-mediated global transcription, including those of cell-migration- and cell-invasion-associated genes. Crucially, low Caspase-8 expression in cervical cancer patients leads to poor prognosis, higher CDK9 phosphorylation at Thr186, and increased RNAPII activity in cervical cancer cell lines and patient biopsies. Caspase-8 knock-out cells were also more resistant to the small-molecule CDK9 inhibitor BAY1251152 in both 2D- and 3D-culture conditions. Combining BAY1251152 with Cisplatin synergistically overcame chemoresistance of Caspase-8-deficient cervical cancer cells. Therefore, Caspase-8 expression could be a marker in chemoresistant cervical tumors, suggesting CDK9 inhibitor treatment for their sensitization to Cisplatin-based chemotherapy.

Cell Survival and Cell Death at the Intersection of Autophagy and Apoptosis: Implications for Current and Future Cancer Therapeutics

Autophagy and apoptosis are functionally distinct mechanisms for cytoplasmic and cellular turnover. While these two pathways are distinct, they can also regulate each other, and central components of the apoptosis or autophagy pathway regulate both processes directly. Furthermore, several upstream stress-inducing signaling pathways can influence both autophagy and apoptosis. The crosstalk between autophagy and apoptosis has an integral role in pathological processes, including those related to cancer, homeostasis, and aging. Apoptosis is a form of programmed cell death, tightly regulated by various cellular and biochemical mechanisms, some of which have been the focus of drug discovery efforts targeting cancer therapeutics. Autophagy is a cellular degradation pathway whereby cells recycle macromolecules and organelles to generate energy when subjected to stress. Autophagy can act as either a prodeath or a prosurvival process and is both tissue and microenvironment specific. In this review we describe five groups of proteins that are integral to the apoptosis pathway and discuss their role in regulating autophagy. We highlight several apoptosis-inducing small molecules and biologics that have been developed and advanced into the clinic and discuss their effects on autophagy. For the most part, these apoptosis-inducing compounds appear to elevate autophagy activity. Under certain circumstances autophagy demonstrates cytoprotective functions and is overactivated in response to chemo- or radiotherapy which can lead to drug resistance, representing a clinical obstacle for successful cancer treatment. Thus, targeting the autophagy pathway in combination with apoptosis-inducing compounds may be a promising strategy for cancer therapy.

Autophagy and apoptosis cascade: which is more prominent in neuronal death?

Autophagy and apoptosis are two crucial self-destructive processes that maintain cellular homeostasis, which are characterized by their morphology and regulated through signal transduction mechanisms. These pathways determine the fate of cellular organelle and protein involved in human health and disease such as neurodegeneration, cancer, and cardiovascular disease. Cell death pathways share common molecular mechanisms, such as mitochondrial dysfunction, oxidative stress, calcium ion concentration, reactive oxygen species, and endoplasmic reticulum stress. Some key signaling molecules such as p53 and VEGF mediated angiogenic pathway exhibit cellular and molecular responses resulting in the triggering of apoptotic and autophagic pathways. Herein, based on previous studies, we describe the intricate relation between cell death pathways through their common genes and the role of various stress-causing agents. Further, extensive research on autophagy and apoptotic machinery excavates the implementation of selective biomarkers, for instance, mTOR, Bcl-2, BH3 family members, caspases, AMPK, PI3K/Akt/GSK3β, and p38/JNK/MAPK, in the pathogenesis and progression of neurodegenerative diseases. This molecular phenomenon will lead to the discovery of possible therapeutic biomolecules as a pharmacological intervention that are involved in the modulation of apoptosis and autophagy pathways. Moreover, we describe the potential role of micro-RNAs, long non-coding RNAs, and biomolecules as therapeutic agents that regulate cell death machinery to treat neurodegenerative diseases. Mounting evidence demonstrated that under stress conditions, such as calcium efflux, endoplasmic reticulum stress, the ubiquitin-proteasome system, and oxidative stress intermediate molecules, namely p53 and VEGF, activate and cause cell death. Further, activation of p53 and VEGF cause alteration in gene expression and dysregulated signaling pathways through the involvement of signaling molecules, namely mTOR, Bcl-2, BH3, AMPK, MAPK, JNK, and PI3K/Akt, and caspases. Alteration in gene expression and signaling cascades cause neurotoxicity and misfolded protein aggregates, which are characteristics features of neurodegenerative diseases. Excessive neurotoxicity and misfolded protein aggregates lead to neuronal cell death by activating death pathways like autophagy and apoptosis. However, autophagy has a dual role in the apoptosis pathways, i.e., activation and inhibition of the apoptosis signaling. Further, micro-RNAs and LncRNAs act as pharmacological regulators of autophagy and apoptosis cascade, whereas, natural compounds and chemical compounds act as pharmacological inhibitors that rescue neuronal cell death through inhibition of apoptosis and autophagic cell death.

Caspase Inhibition Affects the Expression of Autophagy-Related Molecules in Chondrocytes

Objective. Caspases, cysteine proteases traditionally associated with apoptosis and inflammation, have recently been identified as important regulators of autophagy and reported within the growth plate, a cartilaginous part of the developing bone. The aim of this research was to identify novel autophagy-related molecules affected by inhibition of pro-apoptotic caspases in chondrocytes. Design. Chondrocyte micromasses derived from mouse limb buds were treated with pharmacological inhibitors of caspases. Autophagy-related gene expression was examined and possible novel molecules were confirmed by real-time polymerase chain reaction and immunocytofluorescence. Individual caspases inhibitors were used to identify the effect of specific caspases. Results. Chondrogenesis accompanied by caspase activation and autophagy progression was confirmed in micromass cultures. Expression of several autophagy-associated genes was significantly altered in the caspases inhibitors treated groups with the most prominent decrease for Pik3cg and increase of Tnfsf10. The results showed the specific pro-apoptotic caspases that play a role in these effects. Importantly, use of caspase inhibitors mimicked changes triggered by an autophagy stimulator, rapamycin, linking loss of caspase activity to an increase in autophagy. Conclusion. Caspase inhibition significantly affects regulation of autophagy-related genes in chondrocytes cultures. Detected markers are of importance in diagnostics and thus the data presented here open new perspectives in the field of cartilage development and degradation.

ATG 4B Serves a Crucial Role in RCE-4-Induced Inhibition of the Bcl-2-Beclin 1 Complex in Cervical Cancer Ca Ski Cells

RCE-4, a steroidal saponin isolated from Reineckia carnea, has been studied previously and has exhibited promising anti-cervical cancer properties by inducing programmed cell death (PCD) of Ca Ski cells. Considering the cancer cells developed various pathways to evade chemotherapy-induced PCD, there is, therefore, an urgent need to further explore the potential mechanisms underlying its actions. The present study focused on targeting the Bcl-2–Beclin 1 complex, which is known as the key regulator of PCD, to deeply elucidate the molecular mechanism of RCE-4 against cervical cancer. The effects of RCE-4 on the Bcl-2–Beclin 1 complex were investigated by using the co-immunoprecipitation assay. In addition, autophagy-related genes (ATG) were also analyzed due to their special roles in PCD. The results demonstrated that RCE-4 inhibited the formation of the Bcl-2–Beclin 1 complex in Ca Ski cells via various pathways, and ATG 4B proteins involved in this process served as a key co-factor. Furthermore, based on the above, the sensitivity of RCE-4 to Ca Ski cells was significantly enhanced by inhibiting the expression of the ATG 4B by applying the ATG 4B siRNA plasmid.

Anti-HER2 monoclonal antibodies intensify the susceptibility of human gastric cancer cells to etoposide by promoting apoptosis, but not autophagy

BACKGROUND

Gastric cancer (GC) is a multifactorial disease with high mortality. Anti-HER2 therapy is a promising strategy in GC treatment and trastuzumab was approved by FDA (Food and Drug Administration) as the first and the second line of treatment of the disease.

PURPOSE

The aim of the study was to examine the effectiveness of a combination of etoposide with trastuzumab or pertuzumab in AGS gastric cancer cells and breast cancer cells such as MCF-7, MDA-MB-231 and HCC1954.

METHODS AND FINDINGS

The cytotoxic effects of the tested compounds against gastric and breast cancer cells were checked by MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide) assay. The anti-proliferative potential was analyzed by the incorporation of [3H]-thymidine into DNA. Fluorescent microscopy and flow cytometry was used to demonstrate the effect of the compounds on apoptosis. The mitochondrial membrane potential, and the activity of caspase-8 and caspase-9 were assessed. Autophagosomes and autolysosomes formation was checked by flow cytometry. The concentrations of Beclin-1, LC3A and LC3B were performed using ELISA. The expression of LC3A/B was also determined. The results from our study proved that the combination of etoposide with anti-HER2 antibodies was not cytotoxic against breast cancer cells, whereas the combination of etoposide with anti-HER2 antibodies decreased viability and DNA biosynthesis in gastric cancer cells. The interaction of etoposide with pertuzumab or trastuzumab induced programmed cell death via extrinsic and intrinsic apoptotic pathways in AGS gastric cancer cells, but did not affect autophagy, where a decrease of Beclin-1, LC3A and LC3B was observed in comparison with the untreated control.

CONCLUSIONS

The study demonstrated that etoposide (12.5 μM) with pertuzumab represent a promising strategy in gastric cancer treatment, but further in vivo examinations are also required.

Binding Features and Functions of ATG3

Autophagy is an evolutionarily conserved catabolic process that is essential for maintaining cellular, tissue, and organismal homeostasis. Autophagy-related (ATG) genes are indispensable for autophagosome formation. ATG3 is one of the key genes involved in autophagy, and its homologs are common in eukaryotes. During autophagy, ATG3 acts as an E2 ubiquitin-like conjugating enzyme in the ATG8 conjugation system, contributing to phagophore elongation. ATG3 has also been found to participate in many physiological and pathological processes in an autophagy-dependent manner, such as tumor occurrence and progression, ischemia-reperfusion injury, clearance of pathogens, and maintenance of organelle homeostasis. Intriguingly, a few studies have recently discovered the autophagy-independent functions of ATG3, including cell differentiation and mitosis. Here, we summarize the current knowledge of ATG3 in autophagosome formation, highlight its binding partners and binding sites, review its autophagy-dependent functions, and provide a brief introduction into its autophagy-independent functions.

Autophagy Modulators in Cancer Therapy

Autophagy is a process of self-degradation that plays an important role in removing damaged proteins, organelles or cellular fragments from the cell. Under stressful conditions such as hypoxia, nutrient deficiency or chemotherapy, this process can also become the strategy for cell survival. Autophagy can be nonselective or selective in removing specific organelles, ribosomes, and protein aggregates, although the complete mechanisms that regulate aspects of selective autophagy are not fully understood. This review summarizes the most recent research into understanding the different types and mechanisms of autophagy. The relationship between apoptosis and autophagy on the level of molecular regulation of the expression of selected proteins such as p53, Bcl-2/Beclin 1, p62, Atg proteins, and caspases was discussed. Intensive studies have revealed a whole range of novel compounds with an anticancer activity that inhibit or activate regulatory pathways involved in autophagy. We focused on the presentation of compounds strongly affecting the autophagy process, with particular emphasis on those that are undergoing clinical and preclinical cancer research. Moreover, the target points, adverse effects and therapeutic schemes of autophagy inhibitors and activators are presented.

Regulation of Caspase-8 Activity at the Crossroads of Pro-Inflammation and Anti-Inflammation

Caspase-8 has been classified as an apoptotic caspase, and its initial definition was an initiator of extrinsic cell death. During the past decade, the concept of caspase-8 functioning has been changed by findings of its additional roles in diverse biological processes. Although caspase-8 was not originally thought to be involved in the inflammation process, many recent works have determined that caspase-8 plays an important role in the regulatory functions of inflammatory processes. In this review, we describe the recent advances in knowledge regarding the manner in which caspase-8 modulates the inflammatory responses concerning inflammasome activation, cell death, and cytokine induction.

Molecular Action of Polyphenols in Leukaemia and Their Therapeutic Potential

Leukaemia is a malignant disease of the blood. Current treatments for leukaemia are associated with serious side-effects. Plant-derived polyphenols have been identified as potent anti-cancer agents and have been shown to work synergistically with standard chemotherapy agents in leukaemia cell lines. Polyphenols have multiple mechanisms of action and have been reported to decrease cell proliferation, arrest cell cycle and induce apoptosis via the activation of caspase (3, 8 and 9); the loss of mitochondrial membrane potential and the release of cytochrome c. Polyphenols have been shown to suppress activation of transcription factors, including NF-kB and STAT3. Furthermore, polyphenols have pro-oxidant properties, with increasing evidence that polyphenols inhibit the antioxidant activity of glutathione, causing oxidative DNA damage. Polyphenols also induce autophagy-driven cancer cell death and regulate multidrug resistance proteins, and thus may be able to reverse resistance to chemotherapy agents. This review examines the molecular mechanism of action of polyphenols and discusses their potential therapeutic targets. Here, we discuss the pharmacological properties of polyphenols, including their anti-inflammatory, antioxidant, anti-proliferative, and anti-tumour activities, and suggest that polyphenols are potent natural agents that can be useful therapeutically; and discuss why data on bioavailability, toxicity and metabolism are essential to evaluate their clinical use.

Role of Hypoxia-Mediated Autophagy in Tumor Cell Death and Survival

Programmed cell death or type I apoptosis has been extensively studied and its contribution to the pathogenesis of disease is well established. However, autophagy functions together with apoptosis to determine the overall fate of the cell. The cross talk between this active self-destruction process and apoptosis is quite complex and contradictory as well, but it is unquestionably decisive for cell survival or cell death. Autophagy can promote tumor suppression but also tumor growth by inducing cancer-cell development and proliferation. In this review, we will discuss how autophagy reprograms tumor cells in the context of tumor hypoxic stress. We will illustrate how autophagy acts as both a suppressor and a driver of tumorigenesis through tuning survival in a context dependent manner. We also shed light on the relationship between autophagy and immune response in this complex regulation. A better understanding of the autophagy mechanisms and pathways will undoubtedly ameliorate the design of therapeutics aimed at targeting autophagy for future cancer immunotherapies.

Autophagy: Mechanisms and Therapeutic Potential of Flavonoids in Cancer

Autophagy, which is a conserved biological process and essential mechanism in maintaining homeostasis and metabolic balance, enables cells to degrade cytoplasmic constituents through lysosomes, recycle nutrients, and survive during starvation. Autophagy exerts an anticarcinogenic role in normal cells and inhibits the malignant transformation of cells. On the other hand, aberrations in autophagy are involved in gene derangements, cell metabolism, the process of tumor immune surveillance, invasion and metastasis, and tumor drug-resistance. Therefore, autophagy-targeted drugs may function as anti-tumor agents. Accumulating evidence suggests that flavonoids have anticarcinogenic properties, including those relating to cellular proliferation inhibition, the induction of apoptosis, autophagy, necrosis, cell cycle arrest, senescence, the impairment of cell migration, invasion, tumor angiogenesis, and the reduction of multidrug resistance in tumor cells. Flavonoids, which are a group of natural polyphenolic compounds characterized by multiple targets that participate in multiple pathways, have been widely studied in different models for autophagy modulation. However, flavonoid-induced autophagy commonly interacts with other mechanisms, comprehensively influencing the anticancer effect. Accordingly, targeted autophagy may become the core mechanism of flavonoids in the treatment of tumors. This paper reviews the flavonoid-induced autophagy of tumor cells and their interaction with other mechanisms, so as to provide a comprehensive and in-depth account on how flavonoids exert tumor-suppressive effects through autophagy.

Crosstalk between oxidative stress, autophagy and apoptosis in hemoporfin photodynamic therapy treated human umbilical vein endothelial cells

BACKGROUND

Photodynamic therapy (PDT) provides a treatment for port-wine stain (PWS) using hemoporfin (hematoporphyrin monomethyl ether, HMME), a novel photosensitizer, reporting better efficacy and lower recurrence rate. This study investigated the effects of HMME-PDT on human umbilical vein endothelial cells (HUVECs) as well as underlying mechanisms.

METHODS

Cell proliferation ability was measured by CCK8 assay and cell apoptosis was determined by TUNEL assay and Western blot analysis. Confocal fluorescence microscopy monitoring RFP-GFP-LC3 transfected HUVECs and Western blot analysis were used to evaluate autophagy. 3-Methyladenine (3-MA), Z-VAD-FMK, N-acetylcysteine (NAC) were used for inhibitor studies.

RESULTS

HMME-PDT decreased cell proliferation ability in an HMME concentration and light dose-dependent manner. Oxidative stress played an important role in HMME-PDT induced cell apoptosis and autophagy in HUVECs. Pretreatment with Z-VAD-FMK, the inhibitor of apoptosis, enhanced HMME-PDT induced autophagy. 3-MA, the suppressor of autophagy, significantly increased HMME-PDT induced apoptosis rates.

CONCLUSIONS

Our study demonstrated that HMME-PDT induced both apoptosis and autophagy in HUVECs via oxidative stress. Our data suggested that HMME-PDT- induced autophagy was able to prevent apoptotic cell death of HUVECs and rendered them more resistant to HMME-PDT induced toxicity.

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.

Ultra-structural study of the indomethacin-induced apoptosis and autophagy in rat gastric parietal cells

BACKGROUND AND AIM OF THE WORK

Indomethacin (IND), a non-steroidal anti-inflammatory drug, can induce gastric mucosal ulcerations. To date, the ultra-structural changes in the parietal cells (PCs) of the gastric mucosa following the intake of IND are mostly unknown. We carried out the current investigation to get insights into this issue.

MATERIALS AND METHODS

We established an animal model consisting of 35 adult male Sprague Dawley rats. The animals were divided into three groups, including; control (normal feeding), fasting, and indomethacin-treated groups. After treatment of 18-h fasting rats with IND, they were sacrificed at 3, 6, and 12-h intervals. The morphological features, including the apoptotic, and autophagic changes in the gastric mucosa PCs were examined using transmission electron microscopy.

RESULTS

In normal feeding animals (control group), the gastric PCs were present in various stages of activity. Fasting was associated with the predominance of the inactive parietal cells with features of up-regulated autophagy. In the IND -treated animals (at 3-h interval), PCs showed prominent autophagic changes, and subtle apoptotic cell death. In the IND -treated animals (at 6-12-h interval), PCs showed prominent apoptotic changes, and subtle autophagic features.

CONCLUSIONS

Our study indicates that IND treatment could induce gastropathy through time-dependent alterations in the autophagic and apoptotic machinery of PCs. Further studies are needed to examine the underlying molecular mechanisms.

Caspase-8: The double-edged sword

Caspase-8 is a cysteine - aspartate specific protease that classically triggers the extrinsic apoptotic pathway, in response to the activation of cell surface Death Receptors (DRs) like FAS, TRAIL-R and TNF-R. Besides it's roles in triggering death receptor-mediated apoptosis, Caspase-8 has also been implicated in the onsets of anoikis, autophagy and pyroptosis. Furthermore, Caspase-8 also plays a crucial pro-survival function by inhibiting an alternative form of programmed cell death called necroptosis. Low expression levels of pro-Caspase-8 is therefore associated with the malignant transformation of cancers. However, the long-held notion that pro-Caspase-8 expression/activity is generally lost in most cancers, thereby contributing to apoptotic escape and enhanced resistance to anti-cancer therapeutics, has been found to be true for only a minority of cancers types. In the majority of cases, pro-Caspase-8 expression is maintained and sometimes elevated, while it's apoptotic activity is regulated through different mechanisms. This supports the notion that the non-apoptotic functions of Caspase-8 offer growth advantage in these cancer types and have, therefore, gained renewed interest in the recent years. In light of these reasons, a number of therapeutic approaches have been employed, with the intent of targeting pro-Caspase-8 in cancer cells. In this review, we would attempt to discuss - the classic roles of Caspase-8 in initiating apoptosis; it's non-apoptotic functions; it's the clinical significance in different cancer types; and the therapeutic applications exploiting the ability of pro-Caspase-8 to regulate various cellular functions.

Autophagy-mediated regulation of neutrophils and clinical applications

Autophagy, an adaptive catabolic process, plays a cytoprotective role in enabling cellular homeostasis in the innate and adaptive immune systems. Neutrophils, the most abundant immune cells in circulation, are professional killers that orchestrate a series of events during acute inflammation. The recent literature indicates that autophagy has important roles in regulating neutrophil functions, including differentiation, degranulation, metabolism and neutrophil extracellular trap formation, that dictate neutrophil fate. It is also becoming increasingly clear that autophagy regulation is critical for neutrophils to exert their immunological activity. However, evidence regarding the systematic communication between neutrophils and autophagy is insufficient. Here, we provide an updated overview of the function of autophagy as a regulator of neutrophils and discuss its clinical relevance to provide novel insight into potentially relevant treatment strategies.