Caspase involvement in autophagy

c-Jun N-terminal Kinase Supports Autophagy in Testicular Ischemia but Triggers Apoptosis in Ischemia-Reperfusion Injury

Oxidative stress triggered by testicular torsion and detorsion in young males could negatively impact future fertility. Using a rat animal model for testicular IRI (tIRI), we aim to study the induction of autophagy (ATG) during testicular ischemia and tIRI and the role of oxidative-stress-induced c-Jun N-terminal Kinase (JNK) as a cytoprotective mechanism. Sixty male Sprague-Dawley rats were divided into five groups: sham, ischemia only, ischemia+SP600125 (a JNK inhibitor), tIRI only, and tIRI+SP600125. The tIRI rats underwent an ischemic injury for 1 h followed by 4 h of reperfusion, while ischemic rats were subjected to 1 h of ischemia only without reperfusion. Testicular-ischemia-induced Beclin 1 and LC3B expression was associated with decreased p62/SQSTM1 expression, increased ATP and alkaline phosphatase (AP) activity, and slightly impaired spermatogenesis. SP600125 treatment improved p62 expression and reduced the levels of Beclin 1 and LC3B but did not affect ATP or AP levels. The tIRI-induced apoptosis lowered the expression of the three ATG proteins and AP activity, activated caspase 3, and caused spermatogenic arrest. SP600125-inhibited JNK during tIRI restored sham levels to all investigated parameters. This study emphasizes the regulatory role of JNK in balancing autophagy and apoptosis during testicular oxidative injuries.

OTUD7B knockdown inhibits proliferation and autophagy through AKT/mTOR signaling pathway in human prostate cancer cell

Prostate cancer (PCa) is the second leading disease of cancer-related death in men around the world, and it is almost impossible to treat advanced PCa. OTUD7B is a member of the deubiquitinase family that undergoes a post-translational transformation process, which is essential for cell stability and signaling and is known to play a critical role in cancer. However, its role in PCa has not been discovered. The aim of the study was to investigate the expression and mechanism of OTUD7B in PCa cells. According to the database, high OTUD7B expression showed a poor prognosis. Therefore, we downregulated OTUD7B using siRNA and confirmed the role of OTUD7B in PC3 prostate cancer cells. OTUD7B knockdown effectively induced apoptosis and inhibited the proliferation in PC3 cells. OTUD7B knockdown inhibited autophagy through AKT/mTOR signaling. We also confirmed the relationship between AKT/mTOR signaling and autophagy through rapamycin, an mTOR inhibitor. Taken together, OTUD7B promotes the proliferation, and autophagy, and inhibits apoptosis of prostate cancer cells via the AKT/mTOR signaling pathway.

Cadmium toxicity and autophagy: a review

Cadmium (Cd) is an important environmental pollutant that poses a threat to human health and represents a critical component of air pollutants, food sources, and cigarette smoke. Cd is a known carcinogen and has toxic effects on the environment and various organs in humans. Heavy metals within an organism are difficult to biodegrade, and those that enter the respiratory tract are difficult to remove. Autophagy is a key mechanism for counteracting extracellular (microorganisms and foreign bodies) or intracellular (damaged organelles and proteins that cannot be degraded by the proteasome) stress and represents a self-protective mechanism for eukaryotes against heavy metal toxicity. Autophagy maintains cellular homeostasis by isolating and gathering information about foreign chemicals associated with other molecular events. However, autophagy may trigger cell death under certain pathological conditions, including cancer. Autophagy dysfunction is one of the main mechanisms underlying Cd-induced cytotoxicity. In this review, the toxic effects of Cd-induced autophagy on different human organ systems were evaluated, with a focus on hepatotoxicity, nephrotoxicity, respiratory toxicity, and neurotoxicity. This review also highlighted the classical molecular pathways of Cd-induced autophagy, including the ROS-dependent signaling pathways, endoplasmic reticulum (ER) stress pathway, Mammalian target of rapamycin (mTOR) pathway, Beclin-1 and Bcl-2 family, and recently identified molecules associated with Cd. Moreover, research directions for Cd toxicity regarding autophagic function were proposed. This review presents the latest theories to comprehensively reveal autophagy behavior in response to Cd toxicity and proposes novel potential autophagy-targeted prevention and treatment strategies for Cd toxicity and Cd-associated diseases in humans.

Trifluoperazine mitigates cyclophosphamide-induced hepatic oxidative stress, inflammation, and apoptosis in mice by modulating the AKT/mTOR-driven autophagy and Nrf2/HO-1 signaling cascades

AIM

This study aims to investigate the hepatoprotective effect of the antipsychotic drug trifluoperazine (TFP) against cyclophosphamide (CPA)-induced hepatic injury by exploring its effect on autophagy and the Nrf2/HO-1 signaling pathway.

MAIN METHODS

The hepatotoxicity of CPA was assessed by biochemical analysis of the serum hepatotoxicity markers (ALT, AST, and direct bilirubin), histopathological examination, and ultrastructure analysis by transmission electron microscopy (TEM). The ELISA technique was used to assess the hepatic content of oxidative stress (MDA and SOD) and inflammatory markers (IL-1β and TNF-α). Immunohistochemical assessment was used to investigate the hepatic expression of NF-κB, Nrf2, caspase-3, as well as autophagy flux markers (p62 and LC3B). The mRNA expression of HO-1 was assessed using RT-qPCR. Western blot assay was used to determine the expression of p-AKT and p-mTOR.

KEY FINDINGS

TFP improved CPA-induced hepatotoxicity by reducing the elevated hepatotoxicity markers, and alleviating the histopathological changes with improving ultrastructure alterations. It also reduced oxidative stress by reducing MDA content and upregulating SOD activity. In addition, it exhibited anti-inflammatory and anti-apoptotic effects by decreasing NF-κB expression, IL-1β, TNF-α levels, and caspase-3 expression. Furthermore, TFP-induced hepatoprotection was mediated by favoring Nrf2 expression and increasing the mRNA level of HO-1. As well, it improved autophagy by increasing LC3B expression concurrently with reducing p62 expression. Moreover, TFP modulated the AKT/mTOR pathway by reducing the expression of p-AKT and p-mTOR.

SIGNIFICANCE

TFP significantly protected against CPA-induced hepatotoxicity by upregulating Nrf2/HO-1 signaling along with enhancement of protective autophagy via inhibition of the AKT/mTOR signaling pathway.

Molecular mechanisms in regulation of autophagy and apoptosis in view of epigenetic regulation of genes and involvement of liquid-liquid phase separation

Cellular physiology is critically regulated by multiple signaling nexuses, among which cell death mechanisms play crucial roles in controlling the homeostatic landscape at the tissue level within an organism. Apoptosis, also known as programmed cell death, can be induced by external and internal stimuli directing the cells to commit suicide in unfavourable conditions. In contrast, stress conditions like nutrient deprivation, infection and hypoxia trigger autophagy, which is lysosome-mediated processing of damaged cellular organelle for recycling of the degraded products, including amino acids. Apparently, apoptosis and autophagy both are catabolic and tumor-suppressive pathways; apoptosis is essential during development and cancer cell death, while autophagy promotes cell survival under stress. Moreover, autophagy plays dual role during cancer development and progression by facilitating the survival of cancer cells under stressed conditions and inducing death in extreme adversity. Despite having two different molecular mechanisms, both apoptosis and autophagy are interconnected by several crosslinking intermediates. Epigenetic modifications, such as DNA methylation, post-translational modification of histone tails, and miRNA play a pivotal role in regulating genes involved in both autophagy and apoptosis. Both autophagic and apoptotic genes can undergo various epigenetic modifications and promote or inhibit these processes under normal and cancerous conditions. Epigenetic modifiers are uniquely important in controlling the signaling pathways regulating autophagy and apoptosis. Therefore, these epigenetic modifiers of both autophagic and apoptotic genes can act as novel therapeutic targets against cancers. Additionally, liquid-liquid phase separation (LLPS) also modulates the aggregation of misfolded proteins and provokes autophagy in the cytosolic environment. This review deals with the molecular mechanisms of both autophagy and apoptosis including crosstalk between them; emphasizing epigenetic regulation, involvement of LLPS therein, and possible therapeutic approaches against cancers.

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.

Apoptosis and eryptosis: similarities and differences

Eryptosis is a regulated cell death (RCD) of mature erythrocytes initially described as a counterpart of apoptosis for enucleated cells. However, over the recent years, a growing number of studies have emphasized certain differences between both cell death modalities. In this review paper, we underline the hallmarks of eryptosis and apoptosis and highlight resemblances and dissimilarities between both RCDs. We summarize and critically discuss differences in the impact of caspase-3, Ca2+ signaling, ROS signaling pathways, opposing roles of casein kinase 1α, protein kinase C, Janus kinase 3, cyclin-dependent kinase 4, and AMP-activated protein kinase to highlight a certain degree of divergence between apoptosis and eryptosis. This review emphasizes the crucial importance of further studies that focus on deepening our knowledge of cell death machinery and identifying novel differences between cell death of nucleated and enucleated cells. This might provide evidence that erythrocytes can be defined as viable entities capable of programmed cell destruction. Additionally, the revealed cell type-specific patterns in cell death can facilitate the development of cell death-modulating therapeutic agents.

Cytomorphological Disparities in Invasive Breast Cancer Cells following Neoadjuvant Endocrine Therapy and Chemotherapy

INTRODUCTION

Neoadjuvant endocrine therapy (NAE) offers a breast-conserving surgery rate and clinical response rate similar to those of neoadjuvant chemotherapy (NAC), while presenting fewer adverse events and lower pathological complete response rates. The assessment of pathological response determines degenerative changes and predicts the prognosis of breast cancer treated with NAC. This study clarified the degenerative changes occurring in breast cancer following NAE.

METHODS

Our study encompassed two groups: NAE, consisting of 15 patients, and NAC, comprising 18 patients. Tissue samples were obtained from core needle biopsies and surgeries. Nuclear and cell areas were calculated using Autocell analysis. Furthermore, we assessed markers associated with microtubule depolymerization (KIF2A) and initiators of apoptosis (caspase-9).

RESULTS

In the NAC group, we observed significant increases in both cytoplasmic and cell areas. These changes in cytoplasm and cells were notably more pronounced in the NAC group compared to the NAE group. After treatment, KIF2A exhibited a decrease, with the magnitude of change being greater in the NET group than in the NAC group. However, no discernible differences were found in caspase-9 expression between the two groups.

CONCLUSION

Our findings indicate that NAE induces condensation in cancer cells via cell cycle arrest or apoptosis. Conversely, NAC leads to cell enlargement due to the absence of microtubule depolymerization. These discrepancies underscore the importance of accounting for these distinctions when establishing criteria for evaluating pathological responses.

Resveratrol and quercetin protect from Benzo(a)pyrene-induced autophagy in retinal pigment epithelial cells

PURPOSE

This study aims to investigate the role of Resveratrol (RES) and quercetin (QR) treatments against Benzo(a)pyrene (B(a)p)-induced autophagy in retinal pigment epithelial cells.

METHODS

The IC50 doses of B(a)p, RES and QR in retinal pigment epithelial cells were determined by MTT assay and the relevant agents were administered singly or in combinations to ARPE-19 cells for 24 h. Occurrence of autophagy in the cells was verified by detection of autophagosomes using fluorescence microscope. Also, the mRNA expression levels of LC3 and Beclin 1 genes were analyzed by RT-PCR to collect further data on autophagy. Caspase-3 and IL-1β levels in lysed cells were analyzed by ELISA.

RESULTS

Autophagosomes were detected in B(a)p-treated ARPE-19 cell lines, as well as a 1.787-fold increase in LC3 mRNA expression levels. No autophagosome occurred in RES and QR treatments, and a significant decrease in their percentage amounts were observed in B(a)p + RES and B(a)p + QR. The mRNA expression levels of LC3 and Beclin 1 also supported these findings. B(a)p had no effect on Caspase-3 levels in ARPE-19 cells, but combined with RES and QR, it increased Caspase-3 levels significantly.IL-1β levels were higher in B(a)p, B(a)p + QR, B(a)p + RES, RES and QR than control group. This rise in IL-1β levels was correlated with suppression of mRNA expression levels of Beclin 1.

CONCLUSION

B(a)p exposure caused autophagy in ARPE-19 cells, but did not induce apoptosis. RES and QR treatments prevented B(a)p-induced autophagy. Therefore, RES and QR treatments showed protective effect against potential degenerative diseases caused by chronic exposure to B(a)p.

Translation regulation in response to stress

Cell stresses occur in a wide variety of settings: in disease, during industrial processes, and as part of normal day-to-day rhythms. Adaptation to these stresses requires cells to alter their proteome. Cells modify the proteins they synthesize to aid proteome adaptation. Changes in both mRNA transcription and translation contribute to altered protein synthesis. Here, we discuss the changes in translational mechanisms that occur following the onset of stress, and the impact these have on stress adaptation.

Genetically encoded caspase sensor and RFP-LC3 for temporal analysis of apoptosis-autophagy

The balance between pro-death and pro-survival signaling determines the fate of cells under a variety of pathological and physiological conditions. The pro-cell death signaling, apoptosis, and survival singling, autophagy work in an integrated manner for maintaining cell integrity. Their altered balance drives pathological conditions such as cancer, inflammatory disorders, and neurodegenerative diseases. Dissecting complex crosstalk between autophagy and apoptosis requires simultaneous detection of both events at a single cell level with good temporal resolution in real-time. Here, we have used two distinct fluorescent-based probes of caspase activation and autophagy for generating such sensor cells. Cells stably expressing RFP-LC3 as an autophagy marker were further stably expressed with a FRET-based probe for caspase activation with a nuclear localization signal. The functional validation and live-cell imaging of the sensor cells using selected treatments revealed that stress that induces rapid cell death often fails to induce autophagy signaling, and slow cell death induction triggers simultaneous autophagy signaling with caspase activation. The real-time imaging revealed the time-dependent shift of cells towards caspase activation while autophagy is inhibited confirming basal autophagy confers survival against apoptosis under stress conditions. Confocal imaging also revealed that cells under 3D culture condition maintain increased autophagy over monolayer cultures. High-throughput adaptability of the system extends its application for the screening of compounds that cause caspase activation, autophagy, or both demonstrating the potential utility of the sensor probe for diverse biological applications.

Cellular stress management by caspases

Cellular stress plays a pivotal role in the onset of numerous human diseases. Consequently, the removal of dysfunctional cells, which undergo excessive stress-induced damage via various cell death pathways, including apoptosis, is essential for maintaining organ integrity and function. The evolutionarily conserved family of cysteine-aspartic-proteases, known as caspases, has been a key player in orchestrating apoptosis. However, recent research has unveiled the capability of these enzymes to govern fundamental cellular processes without triggering cell death. Remarkably, some of these non-lethal functions of caspases may contribute to restoring cellular equilibrium in stressed cells. This manuscript discusses how caspases can function as cellular stress managers and their potential impact on human health and disease. Additionally, it sheds light on the limitations of caspase-based therapies, given our still incomplete understanding of the biology of these enzymes, particularly in non-apoptotic contexts.

The elastin-derived peptide (VGVAPG) activates autophagy in neuroblastoma (SH-SY5Y) cells via peroxisome proliferator-activated receptor gamma (PPARγ)

Autophagy is a self-degradative process important for balancing the sources of energy and involved in the development of Alzheimer's disease (AD). To date, a number of papers have shown that elastin-derived peptides (EDPs) affect the expression and activation of peroxisome proliferator-activated receptor gamma (PPARγ), which is crucial for the development of AD and autophagy initiation. Therefore, the aim of the present study was to determine whether EDPs with a Val-Gly-Val-Ala-Pro-Gly (VGVAPG) amino acid sequence activate the autophagic process in undifferentiated SH-SY5Y human neuroblastoma cells. Our study is the first to show that EDPs with the VGVAPG sequence initiate the autophagy process in the undifferentiated SH-SY5Y cell line exhibiting a number of features of normal neuroblasts. In particular, we observed in our study that VGAVPG peptide increased ULK1, AKT, PPARγ, and LC3B protein expression. Moreover, our experiments with the agonist (rosiglitazone) and antagonist (GW9662) of PPARγ confirm that the studied EDP acts through the PPARγ pathway affecting mTOR and finally autophagy. Some studies have shown that autophagy disturbances are involved in the development of AD. Therefore, we believe that our study will provide new evidence of the possible involvement of EDPs (especially VGVAPG) in the development of AD.

Tarin-Loaded Nanoliposomes Activate Apoptosis and Autophagy and Inhibit the Migration of Human Mammary Adenocarcinoma Cells

Background

Tarin, a lectin purified from Colocasia esculenta, promotes in vitro and in vivo immunomodulatory effects allied to promising anticancer and antimetastatic effects against human adenocarcinoma mammary cells. This makes this 47 kDa-protein a natural candidate against human breast cancer, a leading cause of death among women. Tarin encapsulated in pegylated nanoliposomes displays increased effectiveness in controlling the proliferation of a mammary adenocarcinoma lineage comprising MDA-MB-231 cells.

Methods

The mechanisms enrolled in anticancer and antimetastatic responses were investigated by treating MDA-MB-231 cells with nano-encapsulated tarin at 72 μg/mL for up to 48h through flow cytometry and transmission electron microscopy (TEM). The safety of nano-encapsulated tarin towards healthy tissue was also assessed by the resazurin viability assay, and the effect of nanoencapsulated tarin on cell migration was evaluated by scratch assays.

Results

Ultrastructural analyses of MDA-MB-231 cells exposed to nanoencapsulated tarin revealed the accumulation of autophagosomes and damaged organelles, compatible with autophagy-dependent cell death. On the other hand, the flow cytometry investigation detected the increased occurrence of acidic vacuolar organelles, a late autophagosome trait, along with the enhanced presence of apoptotic cells, activated caspase-3/7, and cell cycle arrest at G0/G1. No deleterious effects were observed in healthy fibroblast cells following tarin nanoencapsulated exposition, in contrast to reduced viability in cells exposed to free tarin. The migration of MDA-MB-231 cells was inhibited by nano-encapsulated tarin, with delayed movement by 24 h compared to free tarin.

Conclusion

The nanoliposome formulation delivers tarin in a delayed and sustained manner, as evidenced by the belated and potent antitumoral and anti-migration effects on adenocarcinoma cells, with no toxicity to healthy cells. Although further investigations are required to fully understand antitumorigenic tarin mechanisms, the activation of both apoptotic and autophagic machineries along with the caspase-3/7 pathway, and cell cycle arrest may comprise a part of these mechanisms.

Moschus ameliorates glutamate-induced cellular damage by regulating autophagy and apoptosis pathway

Alzheimer's disease (AD), a neurodegenerative disorder, causes short-term memory and cognition declines. It is estimated that one in three elderly people die from AD or other dementias. Chinese herbal medicine as a potential drug for treating AD has gained growing interest from many researchers. Moschus, a rare and valuable traditional Chinese animal medicine, was originally documented in Shennong Ben Cao Jing and recognized for its properties of reviving consciousness/resuscitation. Additionally, Moschus has the efficacy of "regulation of menstruation with blood activation, relief of swelling and pain" and is used for treating unconsciousness, stroke, coma, and cerebrovascular diseases. However, it is uncertain whether Moschus has any protective effect on AD patients. We explored whether Moschus could protect glutamate (Glu)-induced PC12 cells from cellular injury and preliminarily explored their related action mechanisms. The chemical compounds of Moschus were analyzed and identified by GC-MS. The Glu-induced differentiated PC12 cell model was thought to be the common AD cellular model. The study aims to preliminarily investigate the intervention effect of Moschus on Glu-induced PC12 cell damage as well as their related action mechanisms. Cell viability, lactate dehydrogenase (LDH), mitochondrial reactive oxygen species, mitochondrial membrane potential (MMP), cell apoptosis, autophagic vacuoles, autolysosomes or autophagosomes, proteins related to apoptosis, and the proteins related to autophagy were examined and analyzed. Seventeen active compounds of the Moschus sample were identified based on GC-MS analysis. In comparison to the control group, Glu stimulation increased cell viability loss, LDH release, mitochondrial damage, loss of MMP, apoptosis rate, and the number of cells containing autophagic vacuoles, and autolysosomes or autophagosomes, while these results were decreased after the pretreatment with Moschus and 3-methyladenine (3-MA). Furthermore, Glu stimulation significantly increased cleaved caspase-3, Beclin1, and LC3II protein expression, and reduced B-cell lymphoma 2/BAX ratio and p62 protein expression, but these results were reversed after pretreatment of Moschus and 3-MA. Moschus has protective activity in Glu-induced PC12 cell injury, and the potential mechanism might involve the regulation of autophagy and apoptosis. Our study may promote research on Moschus in the field of neurodegenerative diseases, and Moschus may be considered as a potential therapeutic agent for AD.

Regulation of Tumor Apoptosis of Poriae cutis-Derived Lanostane Triterpenes by AKT/PI3K and MAPK Signaling Pathways In Vitro

Poria cocos is traditionally used as both food and medicine. Triterpenoids in Poria cocos have a wide range of pharmacological activities, such as diuretic, sedative and tonic properties. In this study, the anti-tumor activities of poricoic acid A (PAA) and poricoic acid B (PAB), purified by high-speed counter-current chromatography, as well as their mechanisms and signaling pathways, were investigated using a HepG2 cell model. After treatment with PAA and PAB on HepG2 cells, the apoptosis was obviously increased (p < 0.05), and the cell cycle arrested in the G2/M phase. Studies showed that PAA and PAB can also inhibit the occurrence and development of tumor cells by stimulating the generation of ROS in tumor cells and inhibiting tumor migration and invasion. Combined Polymerase Chain Reaction and computer simulation of molecular docking were employed to explore the mechanism of tumor proliferation inhibition by PAA and PAB. By interfering with phosphatidylinositol-3-kinase/protein kinase B, Mitogen-activated protein kinases and p53 signaling pathways; and further affecting the expression of downstream caspases; matrix metalloproteinase family, cyclin-dependent kinase -cyclin, Intercellular adhesion molecules-1, Vascular Cell Adhesion Molecule-1 and Cyclooxygenase -2, may be responsible for their anti-tumor activity. Overall, the results suggested that PAA and PAB induced apoptosis, halted the cell cycle, and inhibited tumor migration and invasion through multi-pathway interactions, which may serve as a potential therapeutic agent against cancer.

Regulation of Protein-Induced Apoptosis and Autophagy in Human Hepatocytes Treated with Metformin and Paclitaxel In Silico and In Vitro

Metformin and paclitaxel therapy offer promising outcomes in the treatment of liver cancer. Combining paclitaxel with metformin enhances treatment effectiveness and mitigates the adverse effects associated with paclitaxel alone. This study explored the anticancer properties of metformin and paclitaxel in HepG2 liver cancer cells, MCF-7 breast cancer cells, and HCT116 colon cancer cells. The results demonstrated that the combination of these agents exhibited a lower IC50 in the tested cell lines compared to paclitaxel monotherapy. Notably, treating the HepG2 cell line with this combination led to a reduction in the G0/G1 phase and an increase in the S and G2/M phases, ultimately triggering early apoptosis. To further investigate the interaction between the cellular proteins with paclitaxel and metformin, an in silico study was conducted using proteins chosen from a protein data bank (PDB). Among the proteins studied, AMPK-α, EGFRK, and FKBP12-mTOR exhibited the highest binding free energy, with values of -11.01, -10.59, and -15.63 kcal/mol, respectively, indicating strong inhibitory or enhancing effects on these proteins. When HepG2 cells were exposed to both paclitaxel and metformin, there was an upregulation in the gene expression of AMPK-α, a key regulator of the energy balance in cancer growth, as well as apoptotic markers such as p53 and caspase-3, along with autophagic markers including beclin1 and ATG4A. This combination therapy of metformin and paclitaxel exhibited significant potential as a treatment option for HepG2 liver cancer. In summary, the combination of metformin and paclitaxel not only enhances treatment efficacy but also reduces side effects. It induces cell cycle alterations and apoptosis and modulates key cellular proteins involved in cancer growth, making it a promising therapy for HepG2 liver cancer.

Ethanol inhibits pancreatic acinar cell autophagy through upregulation of ATG4B, mediating pathological responses of alcoholic pancreatitis

Excessive alcohol intake is a major risk factor for pancreatitis, sensitizing the exocrine pancreas to stressors by mechanisms that remain obscure. Impaired autophagy drives nonalcoholic pancreatitis, but the effects of ethanol (EtOH) and alcoholic pancreatitis on autophagy are poorly understood. Here, we find that ethanol reduces autophagosome formation in pancreatic acinar cells, both in a mouse model of alcoholic pancreatitis induced by a combination of EtOH diet and cerulein (a CCK ortholog) and in EtOH+CCK-treated acinar cells (ex vivo model). Ethanol treatments decreased pancreatic level of LC3-II, a key mediator of autophagosome formation. This was caused by ethanol-induced upregulation of ATG4B, a cysteine protease that, cell dependently, regulates the balance between cytosolic LC3-I and membrane-bound LC3-II. We show that ATG4B negatively regulates LC3-II in acinar cells subjected to EtOH treatments. Ethanol raised ATG4B level by inhibiting its degradation, enhanced ATG4B enzymatic activity, and strengthened its interaction with LC3-II. We also found an increase in ATG4B and impaired autophagy in a dissimilar, nonsecretagogue model of alcoholic pancreatitis induced by EtOH plus palmitoleic acid. Adenoviral ATG4B overexpression in acinar cells greatly reduced LC3-II and inhibited autophagy. Furthermore, it aggravated trypsinogen activation and necrosis, mimicking key responses of ex vivo alcoholic pancreatitis. Conversely, shRNA Atg4B knockdown enhanced autophagosome formation and alleviated ethanol-induced acinar cell damage. The results reveal a novel mechanism, whereby ethanol inhibits autophagosome formation and thus sensitizes pancreatitis, and a key role of ATG4B in ethanol's effects on autophagy. Enhancing pancreatic autophagy, particularly by downregulating ATG4B, could be beneficial in mitigating the severity of alcoholic pancreatitis.NEW & NOTEWORTHY Ethanol sensitizes mice and humans to pancreatitis, but the underlying mechanisms remain obscure. Autophagy is important for maintaining pancreatic acinar cell homeostasis, and its impairment drives pancreatitis. This study reveals a novel mechanism, whereby ethanol inhibits autophagosome formation through upregulating ATG4B, a key cysteine protease. ATG4B upregulation inhibits autophagy in acinar cells and aggravates pathological responses of experimental alcoholic pancreatitis. Enhancing pancreatic autophagy, particularly by down-regulating ATG4B, could be beneficial for treatment of alcoholic pancreatitis.

Autophagy-related proteins: Potential diagnostic and prognostic biomarkers of aging-related diseases

Autophagy plays a key role in cellular, tissue and organismal homeostasis and in the production of the energy load needed at critical times during development and in response to nutrient shortage. Autophagy is generally considered as a pro-survival mechanism, although its deregulation has been linked to non-apoptotic cell death. Autophagy efficiency declines with age, thus contributing to many different pathophysiological conditions, such as cancer, cardiomyopathy, diabetes, liver disease, autoimmune diseases, infections, and neurodegeneration. Accordingly, it has been proposed that the maintenance of a proper autophagic activity contributes to the extension of the lifespan in different organisms. A better understanding of the interplay between autophagy and risk of age-related pathologies is important to propose nutritional and life-style habits favouring disease prevention as well as possible clinical applications aimed at promoting long-term health.

Autophagy Inhibition with Chloroquine Increased Pro-Apoptotic Potential of New Aziridine-Hydrazide Hydrazone Derivatives against Glioblastoma Cells

Tumor therapy escape due to undesired side effects induced by treatment, such as prosurvival autophagy or cellular senescence, is one of the key mechanisms of resistance that eventually leads to tumor dormancy and recurrence. Glioblastoma is the most frequent and practically incurable neoplasm of the central nervous system; thus, new treatment modalities have been investigated to find a solution more effective than the currently applied standards based on temozolomide. The present study examined the newly synthesized compounds of aziridine-hydrazide hydrazone derivatives to determine their antineoplastic potential against glioblastoma cells in vitro. Although the output of our investigation clearly demonstrates their proapoptotic activity, the cytotoxic effect appeared to be blocked by treatment-induced autophagy, the phenomenon also detected in the case of temozolomide action. The addition of an autophagy inhibitor, chloroquine, resulted in a significant increase in apoptosis triggered by the tested compounds, as well as temozolomide. The new aziridine-hydrazide hydrazone derivatives, which present cytotoxic potential against glioblastoma cells comparable to or even higher than that of temozolomide, show promising results and, thus, should be further investigated as antineoplastic agents. Moreover, our findings suggest that the combination of an apoptosis inducer with an autophagy inhibitor could optimize chemotherapeutic efficiency, and the addition of an autophagy inhibitor should be considered as an optional adjunctive therapy minimizing the risk of tumor escape from treatment.

Cannabinoids Reduce Melanoma Cell Viability and Do Not Interfere with Commonly Used Targeted Therapy in Metastatic Melanoma In Vivo and In Vitro

Background: Cannabinoids are mainly used for recreational purposes, but also made their way into oncology, since these substances can be taken to increase appetite in tumour cachexia. Since there are some hints in the literature that cannabinoids might have some anti-cancerous effects, the aim of this study was to study if and how cannabinoids mediate pro-apoptotic effects in metastatic melanoma in vivo and in vitro and its value besides conventional targeted therapy in vivo. Methods: Several melanoma cell lines were treated with different concentrations of cannabinoids, and anti-cancerous efficacy was assessed by proliferation and apoptosis assays. Subsequent pathway analysis was performed using apoptosis, proliferation, flow cytometry and confocal microscopy data. The efficacy of cannabinoids in combination with trametinib was studied in NSG mice in vivo. Results: Cannabinoids reduced cell viability in multiple melanoma cell lines in a dose-dependent way. The effect was mediated by CB1, TRPV1 and PPARα receptors, whereby pharmacological blockade of all three receptors protected from cannabinoid-induced apoptosis. Cannabinoids initiated apoptosis by mitochondrial cytochrome c release with consecutive activation of different caspases. Essentially, cannabinoids significantly decreased tumour growth in vivo and were as potent as the MEK inhibitor trametinib. Conclusions: We could demonstrate that cannabinoids reduce cell viability in several melanoma cell lines, initiate apoptosis via the intrinsic apoptotic pathway by cytochrome c release and caspase activation and do not interfere with commonly used targeted therapy.

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.

Residual Foci of DNA Damage Response Proteins in Relation to Cellular Senescence and Autophagy in X-Ray Irradiated Fibroblasts

DNA repair (DNA damage) foci observed 24 h and later after irradiation are called "residual" in the literature. They are believed to be the repair sites for complex, potentially lethal DNA double strand breaks. However, the features of their post-radiation dose-dependent quantitative changes and their role in the processes of cell death and senescence are still insufficiently studied. For the first time in one work, a simultaneous study of the association of changes in the number of residual foci of key DNA damage response (DDR) proteins (γH2AX, pATM, 53BP1, p-p53), the proportion of caspase-3 positive, LC-3 II autophagic and SA-β-gal senescent cells was carried out 24-72 h after fibroblast irradiation with X-rays at doses of 1-10 Gy. It was shown that with an increase in time after irradiation from 24 h to 72 h, the number of residual foci and the proportion of caspase-3 positive cells decrease, while the proportion of senescent cells, on the contrary, increases. The highest number of autophagic cells was noted 48 h after irradiation. In general, the results obtained provide important information for understanding the dynamics of the development of a dose-dependent cellular response in populations of irradiated fibroblasts.

In Vitro Cytotoxic Effect of Aqueous Extracts from Leaves and Rhizomes of the Seagrass Posidonia oceanica (L.) Delile on HepG2 Liver Cancer Cells: Focus on Autophagy and Apoptosis

Aqueous extracts from Posidonia oceanica's green and brown (beached) leaves and rhizomes were prepared, submitted to phenolic compound and proteomic analysis, and examined for their potential cytotoxic effect on HepG2 liver cancer cells in culture. The chosen endpoints related to survival and death were cell viability and locomotory behavior, cell-cycle analysis, apoptosis and autophagy, mitochondrial membrane polarization, and cell redox state. Here, we show that 24 h exposure to both green-leaf- and rhizome-derived extracts decreased tumor cell number in a dose-response manner, with a mean half maximal inhibitory concentration (IC₅₀) estimated at 83 and 11.5 μg of dry extract/mL, respectively. Exposure to the IC₅₀ of the extracts appeared to inhibit cell motility and long-term cell replicating capacity, with a more pronounced effect exerted by the rhizome-derived preparation. The underlying death-promoting mechanisms identified involved the down-regulation of autophagy, the onset of apoptosis, the decrease in the generation of reactive oxygen species, and the dissipation of mitochondrial transmembrane potential, although, at the molecular level, the two extracts appeared to elicit partially differentiating effects, conceivably due to their diverse composition. In conclusion, P. oceanica extracts merit further investigation to develop novel promising prevention and/or treatment agents, as well as beneficial supplements for the formulation of functional foods and food-packaging material with antioxidant and anticancer properties.

Pomiferin targets SERCA, mTOR, and P-gp to induce autophagic cell death in apoptosis-resistant cancer cells, and reverses the MDR phenotype in cisplatin-resistant tumors in vivo

Drug resistance in cancer has been classified as innate resistance or acquired resistance, which were characterized by apoptotic defects and ABC transporters overexpression respectively. Therefore, to preclude or reverse these resistance mechanisms could be a promising strategy to improve chemotherapeutic outcomes. In this study, a natural product from Osage Orange, pomiferin, was identified as a novel autophagy activator that circumvents innate resistance by triggering autophagic cell death via SERCA inhibition and activation of the CaMKKβ-AMPK-mTOR signaling cascade. In addition, pomiferin also directly inhibited the P-gp (MDR1/ABCB1) efflux and reversed acquired resistance by potentiating the accumulation and efficacy of the chemotherapeutic agent, cisplatin. In vivo study demonstrated that pomiferin triggered calcium-mediated tumor suppression and exhibited an anti-metastatic effect in the LLC-1 lung cancer-bearing mouse model. Moreover, as an adjuvant, pomiferin potentiated the anti-tumor effect of the chemotherapeutic agent, cisplatin, in RM-1 drug-resistant prostate cancer-bearing mouse model by specially attenuating ABCB1-mediated drug efflux, but not ABCC5, thereby promoting the accumulation of cisplatin in tumors. Collectively, pomiferin may serve as a novel effective agent for circumventing drug resistance in clinical applications.

Pharmacological Targeting of Bcl-2 Induces Caspase 3-Mediated Cleavage of HDAC6 and Regulates the Autophagy Process in Colorectal Cancer

Compound 6d, a spiroindoline compound, exhibits antiproliferative capability against cancer cell lines. However, the exact underlying mechanism of this compound-mediated inhibitory capability remains unclear. Here, we showed that compound 6d is an inhibitor of Bcl-2, which suppresses CRC growth by inducing caspase 3-mediated intrinsic apoptosis of mitochondria. Regarding the underlying mechanism, we identified HDAC6 as a direct substrate for caspase 3, and caspase 3 activation induced by compound 6d directly cleaves HDAC6 into two fragments. Moreover, the cleavage site was located at D1088 in the DMAD-S motif HDAC6. Apoptosis stimulated by compound 6d promoted autophagy initiation by inhibiting interaction between Bcl-2 and Beclin 1, while it led to the accumulation of ubiquitinated proteins and the reduction of autophagic flux. Collectively, our findings reveal that the Bcl-2-caspase 3-HDAC6 cascade is a crucial regulatory pathway of autophagy and identify compound 6d as a novel lead compound for disrupting the balance between apoptosis and autophagy.

Berberine Induces Combined Cell Death in Gastrointestinal Cell Lines

Berberine (BBR) is a plant alkaloid that has various biological activities. The effects of BBR on gastrointestinal cancer (GIC) have also been investigated and anti-tumor effects such as induction of cell death have been reported. However, the mechanism of BBR-induced cell death has not been fully elucidated. To this end, we investigated the effects of BBR using three GIC cell lines. Our analyses revealed that BBR inhibited cell proliferation, invasion, sphere formation, and anticancer drug resistance in all of the cell lines. BBR also induced an increase in mitochondrial superoxide, lipid peroxide and Fe2+ levels, decreased mitochondrial membrane potential and respiration, decreased glutathione peroxidase 4 expression and glutathione and induced Parkin/PINK1-associated mitophagy. BBR, as well as rotenone, inhibited mitochondrial complex I and enhanced complex II, which were associated with autophagy, reactive oxidative species production, and cell death. Inhibition of complex II by malonate abrogated these changes. BBR-induced cell death was partially rescued by ferrostatin-1, deferoxamine, Z-VAD-FMK, and ATG5 knockdown. Furthermore, oral administration of BBR significantly reduced tumor weight and ascites in a syngeneic mouse peritoneal metastasis model using CT26 GIC cells. These findings suggest that BBR induced a combined type of cell death via complex I inhibition and autophagy. The marked anti-tumor and anti-stemness effects are expected to be useful as a new cell death-inducing agent for the treatment of GIC.

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.

Synergic Induction of Autophagic Cell Death in Anaplastic Thyroid Carcinoma

Anaplastic thyroid carcinoma (ATC) has poor prognosis, high mortality rate and lack of effective therapy. A synergic combination of PD-L1 antibody together with cell death promoting substances like deacetylase inhibitors (DACi) and multi-kinase inhibitors (MKI) could sensitize ATC cells and promote decay by autophagic cell death. The PD-L1-inhibitor atezolizumab synergized with panobinostat (DACi) and sorafenib (MKI) leading to significant reduction of the viability, measured by real time luminescence, of three different patient-derived primary ATC cells, of C643 cells and follicular epithelial thyroid cells too. Solo administration of these compounds caused a significant over-expression of autophagy transcripts; meanwhile autophagy proteins were almost not detectable after the single administration of panobinostat, thus supporting a massive autophagy degradation process. Instead, the administration of atezolizumab caused an accumulation of autophagy proteins and the cleavage of the active caspases 8 and 3. Interestingly, only panobinostat and atezolizumab were able to exacerbate the autophagy process by increasing the synthesis, the maturation and final fusion with the lysosomes of the autophagosome vesicles. Despite ATC cells could be sensitized by atezolizumab via the cleavage of the caspases, no reduction of cell proliferation or promotion of cell death was observed. The apoptosis assay evidenced the ability of panobinostat alone and in combination with atezolizumab to induce the phosphatidil serine exposure (early apoptosis) and further the secondary necrosis. Instead, sorafenib was only able to cause necrosis. The increase of caspases activity induced by atezolizumab, the apoptosis and autophagy processes promoted by panobinostat synergize thus promoting cell death in well-established and primary anaplastic thyroid cancer cells. The combined therapy could represent a future clinical application for the treatment of such lethal and untreatable solid cancer.

Inhibition of autophagy reduces the rate of fluoride-induced LS8 apoptosis via regulating ATG5 and ATG7

Excessive fluoride affects ameloblast differentiation and tooth development. The fate of fluorinated ameloblasts is determined by multiple signaling pathways in response to a range of stimuli. Both autophagy and apoptosis are involved in the regulation of dental fluorosis as well as in protein synthesis and enamel mineralization. Emerging evidence suggests that autophagy and apoptosis are interconnected and that their interaction greatly influences cell death. However, the effect of autophagy on apoptosis in fluoride-treated ameloblasts is unclear. Here, we employed an in vitro cellular model of fluorosis in mouse ameloblast-like LS8 cells and induced autophagy using sodium fluoride (NaF). Our findings suggest that NaF treatment induces autophagy in LS8 cells, and ATG5 and ATG7 are important molecules involved in this process. We also showed that NaF treatment reduced cell viability in Atg5/7 siRNA and autophagy inhibitor-treated LS8 cells. More importantly, NaF-induced apoptosis can be reversed by inhibiting early stage of autophagy. In conclusion, our study shows that autophagy is closely related to dental fluorosis, and inhibition of autophagy, especially ATG5/7, reduces fluoride-induced cell death and apoptosis.

The potential effect of Schisandrin-B combination with panitumumab in wild-type and mutant colorectal cancer cell lines: Role of apoptosis and autophagy

Panitumumab is an approved monoclonal antibody for the treatment of colorectal cancer (CRC); however, mutations in EGFR signaling pathway resulted in poor response. Schisandrin-B (Sch-B) is a phytochemical that was suggested to protect against inflammation, oxidative stress, and cell proliferation. The present study aimed to investigate the potential effect of Sch-B on panitumumab-induced cytotoxicity in wild-type Caco-2, and mutant HCT-116 and HT-29 CRC cell lines, and the possible underlying mechanisms. CRC cell lines were treated with panitumumab, Sch-B, and their combination. The cytotoxic effect of drugs was determined by MTT assay. The apoptotic potential was assessed in-vitro by DNA fragmentation and caspase-3 activity. Additionally, autophagy was investigated via microscopic detection of autophagosomes and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) measurement of Beclin-1, Rubicon, LC3-II, and Bcl-2 expression. The drug pair enhanced panitumumab cytotoxicity in all CRC cell lines where IC50 of panitumumab was decreased in Caco-2 cell line. Apoptosis was induced through caspase-3 activation, DNA fragmentation, and Bcl-2 downregulation. Caco-2 cell line treated with panitumumab showed stained acidic vesicular organelles, contrariwise, all cell lines treated with Sch-B or the drug pair displayed green fluorescence indicating the lack of autophagosomes. qRT-PCR revealed the downregulation of LC3-II in all CRC cell lines, Rubicon in mutant cell lines, and Beclin-1 in HT-29 cell line only. Sch-B at 6.5 µM promoted panitumumab-induced apoptotic cell death, in-vitro, via caspase-3 activation and Bcl-2 downregulation, rather than autophagic cell death. This novel combination therapy against CRC, allows the reduction of panitumumab dose to guard against its adverse effects.

Role of renal tubular programed cell death in diabetic kidney disease

The pathogenic mechanism of diabetic kidney disease (DKD) is involved in various functions; however, its inadequate characterisation limits the availability of effective treatments. Tubular damage is closely correlated with renal function and is thought to be the main contributor to the injury observed in early DKD. Programed cell death (PCD) occurs during the biological development of the living body. Accumulating evidence has clarified the fundamental role of abnormalities in tubular PCD during DKD pathogenesis. Among PCD types, classical apoptosis, autophagic cell death, and pyroptosis are the most studied and will be the focus of this review. Our review aims to elucidate the current knowledge of the mechanism of DKD and the potential therapeutic potential of drugs targeting tubular PCD pathways in DKD.

Histone deacetylation-regulated cell surface Siglec-7 expression promoted megakaryocytic maturation and enhanced platelet-like particle release

BACKGROUND

Functioning as important hematologic cells for hemostasis, wound healing and immune defense platelets are produced before being released into the blood by cytoplasmic fragmentation at the end of the megakaryocyte (MK) differentiation, during which the involvement of both apoptosis and autophagy has been reported. Inhibitory sialic acid-binding immunoglobulin-like lectin-7 gene (Siglec-7) can be expressed on platelets and induce apoptosis on activation for uncharacterized function.

OBJECTIVE

We aimed to investigate the regulatory mechanism for Siglec-7 activation along MK differentiation and its physiologic role during the MK maturation and platelet formation.

METHODS

By using 2 well-established MK differentiation models (HEL and K562) and human primary CD34⁺ cell, we examined the upregulations of transcript and protein levels of Siglec-7 during MK differentiation, and the effect of Siglec-7 surface presence on MK differentiation and platelet-like particles (PLPs) release.

RESULTS

We show that both transcripts and surface Siglec-7 were elevated during MK differentiation, and the histone deacetylase 1 (HDAC1) acted as a negative regulator for Siglec-7 activation. By increasing Siglec-7 surface expression, we found that increased presence of Siglec-7 not only enhanced MK maturation but also the release of PLPs by activating caspase 3-dependent signaling, as evidenced in the observation of more CD41, polyploidy, and platelet factor 4 transcript formations.

CONCLUSION

In this study, we demonstrated that Siglec-7 activation was subjected to epigenetic regulation, and the resulting induced expression of surface Siglec-7 played an important regulatory role in promoting MK differentiation, maturation, and PLP formation.

p62/SQSTM1 in liver diseases: the usual suspect with multifarious identities

p62/Sequestosome-1 (SQSTM1) is a selective autophagy receptor that recruits and delivers intracellular substrates for bulk clearance through the autophagy lysosomal pathway. Interestingly, p62 also serves as a signaling scaffold to participate in the regulation of multiple physiological processes, including oxidative stress response, metabolism, inflammation, and programmed cell death. Perturbation of p62 activity has been frequently found to be associated with the pathogenesis of many liver diseases. p62 has been identified as a critical component of protein aggregates in the forms of Mallory-Denk bodies (MDBs) or intracellular hyaline bodies (IHBs), which are known to be frequently detected in biopsy samples from alcoholic steatohepatitis (ASH), non-alcoholic steatohepatitis (NASH), and hepatocellular carcinoma (HCC) patients. Importantly, abundance of these p62 inclusion bodies is increasingly recognized as a biomarker for NASH and HCC. Although the level of p62 bodies seems to predict the progression and prognosis of these liver diseases, understanding of the underlying mechanisms by which p62 regulates and contributes to the development and progression of these diseases remains incomplete. In this review, we will focus on the function and regulation of p62, and its pathophysiological roles in the liver, by critically reviewing the findings from preclinical models that recapitulate the pathogenesis and manifestation of these liver diseases in humans. In addition, we will also explore the suitability of p62 as a predictive biomarker and a potential therapeutic target for the treatment of liver diseases, including NASH and HCC, as well as recent development of small-molecule compounds for targeting the p62 signaling axis.

Autophagy and Its Lineage-Specific Roles in the Hematopoietic System

Autophagy is a dynamic process that regulates the selective and nonselective degradation of cytoplasmic components, such as damaged organelles and protein aggregates inside lysosomes to maintain tissue homeostasis. Different types of autophagy including macroautophagy, microautophagy, and chaperon-mediated autophagy (CMA) have been implicated in a variety of pathological conditions, such as cancer, aging, neurodegeneration, and developmental disorders. Furthermore, the molecular mechanism and biological functions of autophagy have been extensively studied in vertebrate hematopoiesis and human blood malignancies. In recent years, the hematopoietic lineage-specific roles of different autophagy-related (ATG) genes have gained more attention. The evolution of gene-editing technology and the easy access nature of hematopoietic stem cells (HSCs), hematopoietic progenitors, and precursor cells have facilitated the autophagy research to better understand how ATG genes function in the hematopoietic system. Taking advantage of the gene-editing platform, this review has summarized the roles of different ATGs at the hematopoietic cell level, their dysregulation, and pathological consequences throughout hematopoiesis.

New Insights of Early Brain Injury after Subarachnoid Hemorrhage: A Focus on the Caspase Family

Spontaneous subarachnoid hemorrhage (SAH), primarily caused by ruptured intracranial aneurysms, remains a prominent clinical challenge with a high rate of mortality and morbidity worldwide. Accumulating clinical trials aiming at the prevention of cerebral vasospasm (CVS) have failed to improve the clinical outcome of patients with SAH. Therefore, a growing number of studies have shifted focus to the pathophysiological changes that occur during the periods of early brain injury (EBI). New pharmacological agents aiming to alleviate EBI have become a promising direction to improve outcomes after SAH. Caspases belong to a family of cysteine proteases with diverse functions involved in maintaining metabolism, autophagy, tissue differentiation, regeneration, and neural development. Increasing evidence shows that caspases play a critical role in brain pathology after SAH. Therefore, caspase regulation could be a potential target for SAH treatment. Herein, we provide an overview pertaining to the current knowledge on the role of caspases in EBI after SAH, and we discuss the promising therapeutic value of caspase-related agents after SAH.

Up-regulation of Sirtuin-1/autophagy signaling in human cerebral ischemia: possible role in caspase-3 mediated apoptosis

Aim

Autophagy is a catabolic process, which plays a pivotal role in neuronal homeostases. Sirtuin-1 (Sirt1, Silent information regulator family protein 1) is a protein deacetylase that is activated by nicotinamide adenine dinucleotide (NAD⁺), is also influenced by starvation and stress response similar to autophagy. Sirt1 is necessary for the induction of autophagy and is critical for neuronal survival in neurodegeneration. The present study investigates the role of Sirt1/autophagy signaling and its possible involvement in neuronal cell death in the brains of cerebral ischemia (CI) patients.

Patients and methods

Autopsied brain tissues from three healthy subjects and ten CI patients were obtained from National Institute of Mental Health and Neurosciences (NIMHANS); Bangalore, India. Western blotting and immunostaining were performed to assess the expression changes in Sirt1, autophagy mediators including Beclin-1, autophagy-related (Atg) proteins-3, 5, 7, 12-5, microtubule-associated protein-1A light chain3 (Lc3-I/II), and caspase-3 in stroke patients.

Results

Our study showed that, in stroke patients, expression of Sirt1, Beclin-1, Atg-3, 5, 7, 12-5, and Lc3-II/I were upregulated. Further, our immunohistochemistry results show increased immunoreactivity of Sirt1, Beclin-1, Atg-7, Lc3-I/II, and cleaved caspase-3 in stroke brains.

Conclusion

The present data suggesting a role for Sirt1/autophagy signaling in regulating neuronal cell survival in CI.

ROS-Induced DNA-Damage and Autophagy in Oral Squamous Cell Carcinoma by Usnea barbata Oil Extract-An In Vitro Study

Oxidative stress is associated with aging, cancers, and numerous metabolic and chronic disorders, and phenolic compounds are well known for their health-promoting role due to their free-radical scavenging activity. These phytochemicals could also exhibit pro-oxidant effects. Due to its bioactive phenolic secondary metabolites, Usnea barbata (L.) Weber ex. F.H. Wigg (U. barbata) displays anticancer and antioxidant activities and has been used as a phytomedicine for thousands of years. The present work aims to analyze the properties of U. barbata extract in canola oil (UBO). The UBO cytotoxicity on oral squamous cell carcinoma (OSCC) CLS-354 cell line and blood cell cultures was explored through complex flow cytometry analyses regarding apoptosis, reactive oxygen species (ROS) levels, the enzymatic activity of caspase 3/7, cell cycle, nuclear shrinkage (NS), autophagy (A), and synthesis of deoxyribonucleic acid (DNA). All these studies were concomitantly performed on canola oil (CNO) to evidence the interaction of lichen metabolites with the constituents of this green solvent used for extraction. The obtained data evidenced that UBO inhibited CLS-354 oral cancer cell proliferation through ROS generation (316.67 × 10⁴), determining higher levels of nuclear shrinkage (40.12%), cell cycle arrest in G0/G1 (92.51%; G0 is the differentiation phase, while during G1 phase occurs preparation for cell division), DNA fragmentation (2.97%), and autophagy (62.98%) than in blood cells. At a substantially higher ROS level in blood cells (5250.00 × 10⁴), the processes that lead to cell death-NS (30.05%), cell cycle arrest in G0/G1 (86.30%), DNA fragmentation (0.72%), and autophagy (39.37%)-are considerably lower than in CLS-354 oral cancer cells. Our work reveals the ROS-mediated anticancer potential of UBO through DNA damage and autophagy. Moreover, the present study suggests that UBO pharmacological potential could result from the synergism between lichen secondary metabolites and canola oil phytoconstituents.

Enhancement of Immunosuppressive Activity of Mesenchymal Stromal Cells by Platelet-Derived Factors is Accompanied by Apoptotic Priming

The pro-inflammatory phase of bone healing, initiated by platelet activation and eventually hematoma formation, impacts bone marrow mesenchymal stromal cells (MSCs) in unknown ways. Here, we created platelet-rich plasma (PRP) hydrogels to study how platelet-derived factors modulate functional properties of encapsulated MSCs in comparison to a non-inflammatory fibrin (FBR) hydrogel environment. MSCs were isolated from human bone marrow, while PRP was collected from pooled apheresis thrombocyte concentrates and used for hydrogel preparation. After their encapsulation in hydrogels for 72 h, retrieved MSCs were analyzed for immunomodulatory activities, apoptosis, stem cell properties, senescence, CD9+, CD63+ and CD81+ extracellular vesicle (EV) release, and metabolism-related changes. PRP-hydrogels stimulated immunosuppressive functions of MSCs, along with their upregulated susceptibility to cell death in communication with PBMCs and augmented caspase 3/7 activity. We found impaired clonal growth and cell cycle progression, and more pronounced β-galactosidase activity as well as accumulation of LC3-II-positive vacuoles in PRP-MSCs. Stimuli derived from PRP-hydrogels upregulated AKT and reduced mTOR phosphorylation in MSCs, which suggests an initiation of survival-related processes. Our results showed that PRP-hydrogels might represent a metabolically stressful environment, inducing acidification of MSCs, reducing polarization of the mitochondrial membrane and increasing lipid accumulation. These features were not detected in FBR-MSCs, which showed reduced CD63+ and CD81+ EV production and maintained clonogenicity. Our data revealed that PRP-derived hematoma components cause metabolic adaptation of MSCs followed by increased immune regulatory functions. For the first time, we showed that PRP stimuli represent a survival challenge and “apoptotic priming” that are detrimental for stem cell-like growth of MSCs and important for their therapeutic consideration.

Graphical Abstract

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.

Caspase-8 mutants activate Nrf2 via phosphorylating SQSTM1 to protect against oxidative stress in esophageal squamous cell carcinoma

Caspase-8, a caspase protein, is involved in the regulation of multiple cell death modes and has a predominant role in cell death. Cancer-associated mutations in the protein-coding region of caspase-8 have been widely reported in several solid tumors and might lead to the loss of its apoptotic function and contribute to the pathogenesis of tumors. However, the specific function and molecular mechanisms of mutant caspase-8 in the development of esophageal squamous cell carcinoma (ESCC) remain unknown. Here, we identified caspase-8 mutants exert tumor-promoting properties in ESCC, patients with the mutants presented a worse prognosis, and caspase-8 mutants lost the suppressive effect on tumor growth in ESCC cells. In addition, we demonstrated that caspase-8 mutants gain a new function of abolishing excess reactive oxygen species (ROS) to maintain ESCC cell growth under oxidative stress. An Nrf2 inhibitor reduced the effects of caspase-8 mutants against oxidative stress. Caspase-8 mutants combined with mTOR to phosphorylate SQSTM1 at Ser349, facilitating the interaction of SQSTM1 and Keap1 and reducing the degradation of the Nrf2 protein. Therefore, our study demonstrated that caspase-8 mutants gain a new function of protecting against oxidative stress via the mTOR/SQSTM1/Keap1/Nrf2 axis in ESCC. Caspase-8 status may be a new prognostic factor for survival in ESCC patients.

The effect of two types of diet on apoptosis indexes, lipid profile and histopathological outcome in acute kidney injury during exercise

Background

Exercise and some pre-AKI diets have been shown to improve injury, apoptosis, and lipid profile. In this study, the effect of two different diets along with exercise training on acute kidney injury (AKI) was investigated. 

Materials and methods

Laboratory rats were randomly divided into four groups of control, standard diet + exercise, exercise + calorie restriction (CR) and exercise + time restriction (TR). Each group was divided into two subgroups of AKI and no AKI. The animals received endurance training and diet regimens before AKI. Fasting blood glucose, serum creatinine, Bcl-2-associated X protein (Bax), B-cell lymphoma 2 (Bcl2) and histopathological outcome of renal tissue as well as serum lipid profile of animals were assessed 24 h after AKI. 

Results

The percentage of changes in renal Bcl2 and Bax after AKI in the group with previous exercise was lower than the group without previous exercise (p < 0.01). After induction of AKI, serum lipid profile changed in non-exercised rats (p < 0.001). Also, after injury, fasting blood glucose levels increased in non-exercised rats (p < 0.05). After injury, the start of both CR and TR diets during exercise caused less change in Bcl2 and Bax of non-exercised rats compared to exercised rats (p < 0.001). CR diet along with exercise improved lipid profile, and also CR diet along exercise decreased fasting blood glucose levels (p < 0.001). Also, both the CR and TR diets during exercise caused fewer changes in histopathological outcome after AKI.

Conclusion

Exercise alone decreased changes in apoptotic and histopathological indexes, fasting blood glucose, as well as lipid profile of rats after AKI. Reduction of apoptosis and improvement of histopathological outcome after AKI appeared more when CR and TR diets were commenced during exercise. The reduction of lipid profile changes was more pronounced in the group that received CR diet during exercise.

Research progress on astrocyte autophagy in ischemic stroke

Ischemic stroke is a highly disabling and potentially fatal disease. After ischemic stroke, autophagy plays a key regulatory role as an intracellular catabolic pathway for misfolded proteins and damaged organelles. Mounting evidence indicates that astrocytes are strongly linked to the occurrence and development of cerebral ischemia. In recent years, great progress has been made in the investigation of astrocyte autophagy during ischemic stroke. This article summarizes the roles and potential mechanisms of astrocyte autophagy in ischemic stroke, briefly expounds on the crosstalk of astrocyte autophagy with pathological mechanisms and its potential protective effect on neurons, and reviews astrocytic autophagy-targeted therapeutic methods for cerebral ischemia. The broader aim of the report is to provide new perspectives and strategies for the treatment of cerebral ischemia and a reference for future research on cerebral ischemia.

Anticolon Cancer Effect of Korean Red Ginseng via Autophagy- and Apoptosis-Mediated Cell Death

Ginseng (Panax ginseng Meyer) has been used in East Asian traditional medicine for a long time. Korean red ginseng (KRG) is effective against several disorders, including cancer. The cytotoxic effects of KRG extract in terms of autophagy- and apoptosis-mediated cell death and its mechanisms were investigated using human colorectal cancer lines. KRG induced autophagy-mediated cell death with enhanced expression of Atg5, Beclin-1, and LC3, and formed characteristic vacuoles in HCT-116 and SNU-1033 cells. An autophagy inhibitor prevented cell death induced by KRG. KRG generated mitochondrial reactive oxygen species (ROS); antioxidant countered this effect and decreased autophagy. KRG caused apoptotic cell death by increasing apoptotic cells and sub-G₁ cells, and by activating caspases. A caspase inhibitor suppressed cell death induced by KRG. KRG increased phospho-Bcl-2 expression, but decreased Bcl-2 expression. Moreover, interaction of Bcl-2 with Beclin-1 was attenuated by KRG. Ginsenoside Rg2 was the most effective ginsenoside responsible for KRG-induced autophagy- and apoptosis-mediated cell death. KRG induced autophagy- and apoptosis-mediated cell death via mitochondrial ROS generation, and thus its administration may inhibit colon carcinogenesis.

Investigation and experimental validation of curcumin-related mechanisms against hepatocellular carcinoma based on network pharmacology

OBJECTIVES

To determine the potential molecular mechanisms underlying the therapeutic effect of curcumin on hepatocellular carcinoma (HCC) by network pharmacology and experimental in vitro validation.

METHODS

The predictive targets of curcumin or HCC were collected from several databases. the identified overlapping targets were crossed with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses using the Database for Annotation, Visualization, and Integrated Discovery (DAVID) platform. Two of the candidate pathways were selected to conduct an experimental verification. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tetrazolium (MTT) assay was used to determine the effect of curcumin on the viability of HepG2 and LO2 cells. The apoptosis and autophagy of HepG2 cells were respectively detected by flow cytometry and transmission electron microscopy. Besides, western blot and real-time polymerase chain reaction (PCR) were employed to verify the p53 apoptotic pathway and adenosine 5'-monophosphate (AMP)‍-activated protein kinase (AMPK) autophagy pathway. HepG2 cells were pretreated with pifithrin-‍α (PFT-‍α) and GSK690693 for further investigation.

RESULTS

The 167 pathways analyzed by KEGG included apoptosis, autophagy, p53, and AMPK pathways. The GO enrichment analysis demonstrated that curcumin was involved in cellular response to drug, regulation of apoptotic pathway, and so on. The in vitro experiments also confirmed that curcumin can inhibit the growth of HepG2 cells by promoting the apoptosis of p53 pathway and autophagy through the AMPK pathway. Furthermore, the protein and messenger RNA (mRNA) of the two pathways were downregulated in the inhibitor-pretreated group compared with the experimental group. The damage-regulated autophagy modulator (DRAM) in the PFT-‍α-pretreated group was downregulated, and p62 in the GSK690693-pretreated group was upregulated.

CONCLUSIONS

Curcumin can treat HCC through the p53 apoptotic pathway and the AMPK/Unc-51-like kinase 1 (ULK1) autophagy pathway, in which the mutual transformation of autophagy and apoptosis may occur through DRAM and p62.

PFN4 is required for manchette development and acrosome biogenesis during mouse spermiogenesis

Profilin 4 (Pfn4) is expressed during spermiogenesis and localizes to the acrosome-acroplaxome-manchette complex. Here, we generated PFN4-deficient mice, with sperm displaying severe impairment in manchette formation. Interestingly, HOOK1 staining suggests that the perinuclear ring is established; however, ARL3 staining is disrupted, suggesting that lack of PFN4 does not interfere with the formation of the perinuclear ring and initial localization of HOOK1, but impedes microtubular organization of the manchette. Furthermore, amorphous head shape and flagellar defects were detected, resulting in reduced sperm motility. Disrupted cis- and trans-Golgi networks and aberrant production of proacrosomal vesicles caused impaired acrosome biogenesis. Proteomic analysis showed that the proteins ARF3, SPECC1L and FKBP1, which are involved in Golgi membrane trafficking and PI3K/AKT pathway, are more abundant in Pfn4^−/− testes. Levels of PI3K, AKT and mTOR were elevated, whereas AMPK level was reduced, consistent with inhibition of autophagy. This seems to result in blockage of autophagic flux, which could explain the failure in acrosome formation. In vitro fertilization demonstrated that PFN4-deficient sperm is capable of fertilizing zona-free oocytes, suggesting a potential treatment for PFN4-related human infertility.

Summary: PFN4-deficient male mice exhibit impaired acrosome formation and malformation of the manchette, leading to amorphous sperm head shape, flagellar abnormalities and sterility.

Resveratrol inhibits HeLa cell proliferation by regulating mitochondrial function

The beneficial roles of resveratrol (RES) in affecting proliferation of multiple cancer cells have attracted intensive attention. However, the underlying mechanism remains unclear. This study aims to bridge the knowledge gap by investigating RES-induced growth inhibition of HeLa cells. Our work focuses on the metergasis of mitochondria in the RES-exposed cells. Therefore, HeLa cells were treated with different concentrations of RES for 30 min and 24 h, respectively. As a result, concentration-dependent increases in cell growth inhibition, ROS (reactive oxygen species) triggering, and LC3-II (light chain 3-II) expression were detected in the HeLa cells exposed to RES for 24 h. Interestingly, a specific concentration-dependent effect was observed in the HeLa cells exposed to RES for 30 min, that is, low concentration RES (≤ 25 μmol/L) reduced ROS levels, inhibited transcription and expression levels of LC3-II, and stimulated mitochondrial respiratory capacities. In contrast, high concentration RES (50 and 100 μmol/L) induced ROS over-production and autophagy in the cells, resulting in decreased levels of mitochondrial membrane potential, mitochondrial DNA copy numbers, and mitochondrial respiratory capacities. Together, our data concluded that RES inhibited HeLa cell proliferation through perturbation of mitochondrial structure and function, and ROS-induced autophagy also played a critical role in the process.

Necroptosis in atherosclerosis

Atherosclerosis, a chronic inflammatory disease, is a leading cause of death worldwide. Vascular endothelial cells (VECs), vascular smooth muscle cells (VSMCs) and macrophages play extremely vital roles in the formation of atherosclerotic plaques and subsequent atherosclerosis. Necroptosis, a caspase-independent programmed cell necrosis, occurs in advanced atherosclerotic plaques and has been implicated in VEC, VSMC and macrophage function. Although necroptosis may have considered as a defensive line against intracellular infection, it can induce a pro-inflammatory state, which will accelerate the disease process. Accordingly, necroptosis plays an important pathophysiologic role. In this review, we explore the role of necroptosis in VECs, VSMCs and macrophages in atherosclerotic plaques and their connection to atherosclerosis.

A peptoid-based inhibitor of protein arginine methyltransferase 1 (PRMT1) induces apoptosis and autophagy in cancer cells

Protein arginine methyltransferases (PRMTs) are S-adenosylmethionine-dependent enzymes that transfer a methyl group to arginine residues within proteins, most notably histones. The nine characterized PRMT family members are divided into three types depending on the resulting methylated product: asymmetric dimethylarginine (Type I PRMT), symmetric dimethylarginine (Type II PRMT), or monomethylated arginine (Type III PRMT). In some cancers, the resulting product can lead to either increased or decreased transcription of cancer-related genes, suggesting PRMT family members may be valid therapeutic targets. Traditionally, peptide-based compounds have been employed to target this family of enzymes, which has resulted in multiple tool and lead compounds being developed. However, peptide-based therapeutics suffer from poor stability and short half-lives, as proteases can render them useless by hydrolytic degradation. Conversely, peptoids, which are peptide-mimetics composed of N-substituted glycine monomers, are less susceptible to hydrolysis, resulting in improved stability and longer half-lives. Herein, we report the development of a bioavailable, peptoid-based PRMT1 inhibitor that induces cell death in MDA468 and HCT116 cancer cell lines while not exhibiting any significant impact on nontumorigenic HepaRG or normal human mammary epithelial cells. Furthermore, the inhibitor described herein appears to induce both apoptosis and autophagy, suggesting it may be a less toxic cytostatic agent. In conclusion, we propose this peptoid-based inhibitor has significant anticancer and therapeutic potential by reducing cell viability, growth, and size in breast and colon cancer. Further experimentation will help determine the mechanism of action and downstream effects of this compound.