Patulin induces pro-survival functions via autophagy inhibition and p62 accumulation

Involvement of multiple forms of cell death in patulin-induced toxicities

Patulin (PAT) is the most common mycotoxin found in moldy fruits and their derived products, and is reported to cause diverse toxic effects, including hepatotoxicity, nephrotoxicity, cardiotoxicity, neurotoxicity, immunotoxicity, gastrointestinal toxicity and dermal toxicity. The cell death induction by PAT is suggested to be a key cellular mechanism involved in PAT-induced toxicities. Accumulating evidence indicates that the multiple forms of cell death are induced in response to PAT exposure, including apoptosis, autophagic cell death, pyroptosis and ferroptosis. Mechanistically, the cell death induction by PAT is associated the oxidative stress induction via reducing the antioxidant capacity or inducing pro-oxidant NADPH oxidase, the activation of mitochondrial pathway via regulating BCL-2 family proteins, the disruption of iron metabolism through ferritinophagy-mediated ferritin degradation, and the induction of the NOD-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome/caspase-1/gasdermin D (GSDMD) pathway. In this review article, we summarize the present understanding of the cell death induction by PAT, discuss the potential signaling pathways underlying PAT-induced cell death, and propose the issues that need to be addressed to promote the development of cell death-based approach to counteract PAT-induced toxicities.

Deoxynivalenol exposure induces oxidative stress and apoptosis in human keratinocytes via PI3K/Akt and MAPK signaling pathway

Deoxynivalenol (DON) is a mycotoxin frequently occurring in human and animal food worldwide, which raises increasing public health concerns. In the present study, we used human keratinocytes (HaCaT cells) as an in vitro model to explore the cytotoxic effect of DON. The results showed that the cells exhibited varying degrees of damage, including decreased cell number and viability, cell shrinkage and floating, when treated with 0.125, 0.25, and 0.5 μg/mL DON for 6, 12, and 24 h, respectively. Furthermore, exposure to DON for 24 h significantly increased the lactate dehydrogenase (LDH) release and intracellular reactive oxygen species (ROS), and prominently decreased the superoxide dismutase (SOD) and catalase (CAT) activity. Additionally, DON exposure induced mitochondrial damage and cell apoptosis through reducing mitochondrial membrane potential. Then, we performed RNA-sequencing to investigate the molecular changes in HaCaT cells after DON exposure. The RNA-sequencing results revealed that DON exposure altered the gene expression involved in apoptosis, MAPK signaling pathway, and PI3K/Akt signaling pathway. Moreover, DON exposure significantly decreased the mRNA and protein expression of Bcl-2, and increased the mRNA and protein expression of Bax, Caspase 3 and COX-2, the protein expression of PI3K, and the phosphorylation levels of Akt, ERK, p38, and JNK. Taken together, these findings suggest that DON exposure could induce cell damage, oxidative stress, and apoptosis in HaCaT cells through the activation of PI3K/Akt and MAPK pathways.

Mycotoxin source and its exposure causing mycotoxicoses

Mycotoxins are toxic compounds produced by fungi such as Aspergillus, Penicillium, Rhizopus, Fusarium spp., and mushrooms. They are present in the mycelium or in the spores of the fungus. They cause human health problems once ingested. This is common in countries with high ambient temperature and relative humidity such as in the tropical regions. The consumption of moldy food and feeds are injurious to people and animals. The linked acute and chronic diseases target organs in humans and animals. The clinical symptoms depend on the intrinsic toxic features of the mycotoxin, the quantity, and length of exposure. The diseases caused by ingesting mycotoxins are reffred as mycotoxicoses. Therefore, it is of interest to document known data on the mycotoxin source and its exposure causing human hazards leading to mycotoxicoses.

More than a Virulence Factor: Patulin Is a Non-Host-Specific Toxin that Inhibits Postharvest Phytopathogens and Requires Efflux for Penicillium Tolerance

Mycotoxin contamination is a leading cause of food spoilage and waste on a global scale. Patulin, a mycotoxin produced by Penicillium spp. during postharvest pome fruit decay, causes acute and chronic effects in humans, withstands pasteurization, and is not eliminated by fermentation. While much is known about the impact of patulin on human health, there are significant knowledge gaps concerning the effect of patulin during postharvest fruit-pathogen interactions. Application of patulin on six apple cultivars reproduced some blue mold symptoms that were cultivar-independent and dose-dependent. Identical symptoms were also observed in pear and mandarin orange. Six Penicillium isolates exposed to exogenous patulin exhibited delayed germination after 24 h, yet all produced viable colonies in 7 days. However, four common postharvest phytopathogenic fungi were completely inhibited by patulin during conidial germination and growth, suggesting the toxin is important for Penicillium to dominate the postharvest niche. Using clorgyline, a broad-spectrum efflux pump inhibitor, we demonstrated that efflux plays a role in Penicillium auto-resistance to patulin during conidial germination. The work presented here contributes new knowledge of patulin auto-resistance, its mode of action, and inhibitory role in fungal-fungal interactions. Our findings provide a solid foundation to develop toxin and decay mitigation approaches.

miR-27b inhibition contributes to cytotoxicity in patulin-exposed HEK293 cells

Patulin (PAT) is a mycotoxin produced by Penicillium and other fungi that contaminate fruit. PAT targets the kidney and is associated with nephrotoxicity. Micro-RNAs (miRNA) may offer new insights into PAT-induced nephrotoxicity. Cytochrome P₄₅₀ family 1, subfamily B, polypeptide 1 (CYP1B1), involved in metabolism of dietary toxins is negatively regulated by miR-27b and linked with the nuclear factor kappa B (NF-κB) pathway and peroxisome proliferator activated receptor gamma (PPARɣ) in renal fibrosis. This study investigated the effects of PAT on miR-27b, CYP1B1, PPARɣ and cytotoxicity in human kidney (HEK293) cells. HEK293 cells were exposed to PAT (2.5 μM, 24h). Protein expression of CYP1B1, PPARɣ, NF-κB (p65), pNF-κB (p65) (phospho-Ser563) and cleaved PARP-1 was quantified using western blotting. QPCR evaluated mRNA levels of CYP1B1, IL-6, miR-27b, OGG1, mtDNA, TFAM and UCP2. Mitochondrial membrane potential and phosphatidylserine (PS) externalization was evaluated by flow cytometry while levels of ATP and caspase -9, -8, -3/7 activity was measured using luminometry. PAT significantly decreased miR-27b levels (p = 0.0014) and increased CYP1B1 mRNA (p = 0.0015) and protein (p = 0.0013) levels. PPARɣ protein expression was significantly increased (p = 0.0002) and associated with decreased NF-κB activation (p = 0.0273) and IL-6 mRNA levels (p = 0.0265). Finally, PAT significantly compromised mitochondrial repair mechanisms and increased apoptotic biomarkers. PAT altered miR-27b levels and PPARɣ, with associated changes to NF-κB activation, downstream IL-6 and CYP1B1 expression. These results show that PAT impairs detoxification mechanisms leading to mitochondrial damage and apoptosis. In conclusion, PAT altered the epigenetic environment and impaired detoxification processes, supporting a mechanism for nephrotoxic outcomes.

Manipulation of IRE1-Dependent MAPK Signaling by a Vibrio Agonist-Antagonist Effector Pair

Diverse bacterial pathogens employ effector delivery systems to disrupt vital cellular processes in the host (N. M. Alto and K. Orth, Cold Spring Harbor Perspect Biol 4:a006114, 2012, https://doi.org/10.1101/cshperspect.a006114). The type III secretion system 1 of the marine pathogen Vibrio parahaemolyticus utilizes the sequential action of four effectors to induce a rapid, proinflammatory cell death uniquely characterized by a prosurvival host transcriptional response (D. L. Burdette, M. L. Yarbrough, A Orvedahl, C. J. Gilpin, and K. Orth, Proc Natl Acad Sci USA 105:12497-12502, 2008, https://doi.org/10.1073/pnas.0802773105; N. J. De Nisco, M. Kanchwala, P. Li, J. Fernandez, C. Xing, and K. Orth, Sci Signal 10:eaa14501, 2017, https://doi.org/10.1126/scisignal.aal4501). Herein, we show that this prosurvival response is caused by the action of the channel-forming effector VopQ that targets the host V-ATPase, resulting in lysosomal deacidification and inhibition of lysosome-autophagosome fusion. Recent structural studies have shown how VopQ interacts with the V-ATPase and, while in the ER, a V-ATPase assembly intermediate can interact with VopQ, causing a disruption in membrane integrity. Additionally, we observed that VopQ-mediated disruption of the V-ATPase activates the IRE1 branch of the unfolded protein response (UPR), resulting in an IRE1-dependent activation of ERK1/2 MAPK signaling. We also find that this early VopQ-dependent induction of ERK1/2 phosphorylation is terminated by the VopS-mediated inhibitory AMPylation of Rho GTPase signaling. Since VopS dampens VopQ-induced IRE1-dependent ERK1/2 activation, we propose that IRE1 activates ERK1/2 phosphorylation at or above the level of Rho GTPases. This study illustrates how temporally induced effectors can work as in tandem as agonist/antagonist to manipulate host signaling and reveals new connections between V-ATPase function, UPR, and MAPK signaling.IMPORTANCE Vibrio parahaemolyticus is a seafood-borne pathogen that encodes two type 3 secretion systems (T3SS). The first system, T3SS1, is thought to be maintained in all strains of V. parahaemolyticus to maintain survival in the environment, whereas the second system, T3SS2, is linked to clinical isolates and disease in humans. Here, we found that first system targets evolutionarily conserved signaling systems to manipulate host cells, eventually causing a rapid, orchestrated cells death within 3 h. We have found that the T3SS1 injects virulence factors that temporally manipulate host signaling. Within the first hour of infection, the effector VopQ acts first by activating host survival signals while diminishing the host cell apoptotic machinery. Less than an hour later, another effector, VopS, reverses activation and inhibition of these signaling systems, ultimately leading to death of the host cell. This work provides example of how pathogens have evolved to manipulate the interplay between T3SS effectors to regulate host signaling pathways.

Patulin activates the NRF2 pathway by modulation of miR-144 expression in HEK293 cells

Patulin (PAT) is a mycotoxin produced by various fungal species that commonly contaminate apples and other fruit products. PAT is associated with glutathione (GSH) depletion and oxidative stress. Cytoprotective and antioxidant (AO) enzymes limit toxic outcomes and confer resistance to oxidative stress by influencing the expression of cytoprotective genes. The induction of these genes is tightly regulated by transcription factor nuclear factor erythroid 2 p45-related factor 2 (NRF2), a potential target of microRNA (miR)-144. This study aims to determine a possible role for miR-144 in NRF2 pathway activation following PAT exposure in human embryonic kidney (HEK293) cells. HEK293 cells were exposed to varying PAT concentrations (0, 0.2, 0.5, 1 μmol/L; 24 h). Protein expression of Keap1, NRF2, and phosphorylated (p) NRF2 (ser40) was quantified using western blotting. Gene expression of NRF2, SOD2, CAT, GPx, NQO1, GSTA1, HMOX, and miR-144 were evaluated by qPCR. PAT significantly decreased miR-144 (p = 0.0249) and concomitantly increased NRF2 protein expression, stability, and activation as evidenced by increased pNRF2 (p = 0.0216) expression and decreased total NRF2 (p = 0.0237). This was consistent with qPCR data which showed increased transcript levels of NRF2 (p = 0.0378) as well as the target genes CAT (p = 0.0273), NQO1 (p = 0.0156), HMOX (p = 0.0249), and GSTA1 (p = 0.0237). No changes were observed in Keap1 expression (p = 0.6444). This study implicates microRNAs in a mechanistic role in PAT-induced toxicity. PAT decreased miR-144 expression leading to NRF2 pathway activation and elevated AO gene expression.

Patulin suppresses α1-adrenergic receptor expression in HEK293 cells

Patulin (PAT) is a common mycotoxin contaminant of apple products linked to impaired metabolic and kidney function. Adenosine monophosphate activated protein kinase (AMPK), abundantly expressed in the kidney, intercedes metabolic changes and renal injury. The alpha-1-adrenergic receptors (α₁-AR) facilitate Epinephrine (Epi)-mediated AMPK activation, linking metabolism and kidney function. Preliminary molecular docking experiments examined potential interactions and AMPK-gamma subunit 3 (PRKAG3). The effect of PAT exposure (0.2-2.5 µM; 24 h) on the AMPK pathway and α₁-AR was then investigated in HEK293 human kidney cells. AMPK agonist Epi determined direct effects on the α₁-AR, metformin was used as an activator for AMPK, while buthionine sulphoximine (BSO) and N-acetyl cysteine (NAC) assessed GSH inhibition and supplementation respectively. ADRA1A and ADRA1D expression was determined by qPCR. α₁-AR, ERK1/2/MAPK and PI3K/Akt protein expression was assessed using western blotting. PAT (1 µM) decreased α₁-AR protein and mRNA and altered downstream signalling. This was consistent in cells stimulated with Epi and metformin. BSO potentiated the observed effect on α₁-AR while NAC ameliorated these effects. Molecular docking studies performed on Human ADRA1A and PRKAG3 indicated direct interactions with PAT. This study is the first to show PAT modulates the AMPK pathway and α₁-AR, supporting a mechanism of kidney injury.

3-Acetyldeoxynivalenol induces lysosomal membrane permeabilization-mediated apoptosis and inhibits autophagic flux in macrophages

3-Acetyldeoxynivalenol (3-Ac-DON), the acetylated derivative of deoxynivalenol (DON), has been reported to be coexisted with DON in various cereal grains. Ingestion of grain-based food products contaminated by 3-Ac-DON might exert deleterious effects on the health of both humans and animals. However, the biological toxicity of 3-Ac-DON on macrophages and the underlying mechanisms remain largely unknown. In the present study, we showed that RAW 264.7 macrophages treated with 0.75 or 1.50 μg/mL of 3-Ac-DON resulted in DNA damage and the related cell cycle arrest at G1 phase and cell death, activation of the ribotoxic stress and the endoplasmic reticulum (ER) stress responses. The 3-Ac-DON-induced cell death was accompanied by a protective autophagy, because gene silencing of Atg5 using the small interfering RNA enhanced cell death. Results of further experiments revealed a role for lysosomal membrane permeabilization in the 3-Ac-DON triggered inhibition of autophagic flux. Additional work also showed that increased lysosomal biogenesis and leakage of cathepsin B (CTSB) from lysosomes to cytosol was critical for the 3-Ac-DON-induced cell death. Importantly, 3-Ac-DON-induced DNA damage and cell death were rescued by CA-074-me, a CTSB inhibitor. Collectively, these results indicated a critical role of lysosomal membrane permeabilization in the 3-Ac-DON-induced apoptosis of RAW 264.7 macrophages.

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

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

Penicillium spp. mycotoxins found in food and feed and their health effects

Mycotoxins are toxic secondary metabolites produced by fungi. These compounds have different structures and target different organs, acting at different steps of biological processes inside the cell. Around 32 mycotoxins have been identified in fungal Penicillium spp. isolated from food and feed. Some of these species are important pathogens which contaminate food, such as maize, cereals, soybeans, sorghum, peanuts, among others. These microorganisms can be present in different steps of the food production process, such as plant growth, harvest, drying, elaboration, transport, and packaging. Although some Penicillium spp. are pathogens, some of them are used in elaboration of processed foods, such as cheese and sausages. This review summarises the Penicillium spp. mycotoxin toxicity, focusing mainly on the subgenus Penicillium, frequently found in food and feed. Toxicity is reviewed both in animal models and cultured cells. Finally, some aspects of their regulations are discussed.

Chloroquine Improves Deoxynivalenol-Induced Inflammatory Response and Intestinal Mucosal Damage in Piglets

We investigated the effects of rapamycin (RAPA) and chloroquine (CQ) in supporting growth performance and the intestinal mucosal barrier in response to deoxynivalenol (DON) in piglets. A total of 32 healthy weaned piglets (bodyweight 7.10 ± 0.58 kg) were divided into four groups and treated daily with RAPA (1 mg/kg BW), CQ (10 mg/kg BW), or a control volume of normal saline (two groups) until the end of the experiment. After feeding a basal diet for seven days, three groups were then switched to mildewed feed containing 1 mg kg/DON for a further seven days. In contrast to the control group, DON-treated piglets showed decreased average daily gain (ADG) and daily feed intake (ADFI), as well as negatively affected intestinal morphology as indicated by villus height, crypt depth, and tight junction protein expression. A group treated with RAPA and DON showed increased intestinal autophagy, aggravated inflammatory responses, and damage to the intestinal mucosa and permeability, leading to reduced growth performance. Meanwhile, a group treated with CQ and DON showed indices comparable to the non-DON control group, with alleviated inflammatory cytokines and healthy intestinal morphology and structure. They also showed better growth performance compared to DON treatment alone. These findings have important implications for mediating autophagy against DON in vivo, as well as the potential for CQ in improving growth performance and maintaining intestinal barrier integrity in weanling piglets.

The Fusarium mycotoxin, 2-Amino-14,16-dimethyloctadecan-3-ol (AOD) induces vacuolization in HepG2 cells

The mycotoxin 2-Amino-14,16-dimethyloctadecan-3-ol (AOD) has been isolated from cultures of the fungus Fusarium avenaceum, one of the most prevalent Fusarium species. AOD is an analogue of sphinganine and 1-deoxysphinganine, important intermediates in the de novo biosynthesis of cellular sphingolipids. Here we studied cellular effects of AOD using the human liver cell line HepG2 as a model system. AOD (10 μM) induced a transient accumulation of vacuoles in the cells. The effect was observed at non-cytotoxic concentrations and was not linked to cell death processes. Proteomic analyses indicated that protein degradation and/or vesicular transport may be a target for AOD. Further studies revealed that AOD had only minor effects on the initiation rate of macropinocytosis and autophagy. However, the AOD-induced vacuoles were lysosomal-associated membrane protein-1 (LAMP-1) positive, suggesting that they most likely originate from lysosomes or late endosomes. Accordingly, both endosomal and autophagic protein degradation were inhibited. Further studies revealed that treatment with concanamycin A or chloroquine completely blocked the AOD-induced vacuolization, suggesting that the vacuolization is dependent of acidic lysosomes. Overall, the results strongly suggest that the increased vacuolization is due to an accumulation of AOD in lysosomes or late endosomes thereby disturbing the later stages of the endolysosomal process.

Critical role of caveolin-1 in aflatoxin B1-induced hepatotoxicity via the regulation of oxidation and autophagy

Aflatoxin B1 (AFB1) is a potent hepatocarcinogen in humans and exposure to AFB1 is known to cause both acute and chronic hepatocellular injury. As the liver is known to be the main target organ of aflatoxin, it is important to identify the key molecules that participate in AFB1-induced hepatotoxicity and to investigate their underlying mechanisms. In this study, the critical role of caveolin-1 in AFB1-induced hepatic cell apoptosis was examined. We found a decrease in cell viability and an increase in oxidation and apoptosis in human hepatocyte L02 cells after AFB1 exposure. In addition, the intracellular expression of caveolin-1 was increased in response to AFB1 treatment. Downregulation of caveolin-1 significantly alleviated AFB1-induced apoptosis and decreased cell viability, whereas overexpression of caveolin-1 reversed these effects. Further functional analysis showed that caveolin-1 participates in AFB1-induced oxidative stress through its interaction with Nrf2, leading to the downregulation of cellular antioxidant enzymes and the promotion of oxidative stress-induced apoptosis. In addition, caveolin-1 was found to regulate AFB1-induced autophagy. This finding was supported by the effect that caveolin-1 deficiency promoted autophagy after AFB1 treatment, leading to the inhibition of apoptosis, whereas overexpression of caveolin-1 inhibited autophagy and accelerated apoptosis. Interestingly, further investigation showed that caveolin-1 participates in AFB1-induced autophagy by regulating the EGFR/PI3K-AKT/mTOR signaling pathway. Taken together, our data reveal that caveolin-1 plays a crucial role in AFB1-induced hepatic cell apoptosis via the regulation of oxidation and autophagy, which provides a potential target for the development of novel treatments to combat AFB1 hepatotoxicity.

Disturbances in H+ dynamics during environmental carcinogenesis

Despite the improvement of diagnostic methods and anticancer therapeutics, the human population is still facing an increasing incidence of several types of cancers. According to the World Health Organization, this growing trend would be partly linked to our environment, with around 20% of cancers stemming from exposure to environmental contaminants, notably chemicals like polycyclic aromatic hydrocarbons (PAHs). PAHs are widespread pollutants in our environment resulting from incomplete combustion or pyrolysis of organic material, and thus produced by both natural and anthropic sources; notably benzo[a]pyrene (B[a]P), i.e. the prototypical molecule of this family, that can be detected in cigarette smoke, diesel exhaust particles, occupational-related fumes, and grilled food. This molecule is a well-recognized carcinogen belonging to group 1 carcinogens. Indeed, it can target the different steps of the carcinogenic process and all cancer hallmarks. Interestingly, H⁺ dynamics have been described as key parameters for the occurrence of several, if not all, of these hallmarks. However, information regarding the role of such parameters during environmental carcinogenesis is still very scarce. The present review will thus mainly give an overview of the impact of B[a]P on H⁺ dynamics in liver cells, and will show how such alterations might impact different aspects related to the finely-tuned balance between cell death and survival processes, thereby likely favoring environmental carcinogenesis. In total, the main objective of this review is to encourage further research in this poorly explored field of environmental molecular toxicology.

Particulate Matter-Induced Aryl Hydrocarbon Receptor Regulates Autophagy in Keratinocytes

Particulate matter (PM), which refers to the mixture of particles present in the air, can have harmful effects. Damage to cells by PM, including disruption of organelles and proteins, can trigger autophagy, and the relationship between autophagy and PM has been well studied. However, the cellular regulators of PM-induced autophagy have not been well characterized, especially in keratinocytes. The Aryl Hydrocarbon Receptor (AhR) is expressed in the epidermis and is activated by PM. In this study, we investigated the role of the AhR in PM-induced autophagy in HaCaT cells. Our results showed that PM led to AhR activation in keratinocytes. Activation of the AhR-target gene CYP1A1 by PM was reduced by co-treatment with α-naphthoflavone (α-NF), an AhR inhibitor. We also evaluated activation of the autophagy pathway in PM-treated keratinocytes. In HaCaT cells, treatment with PM treatment led to the induction of microtubules-associated proteins light chain 3 (LC3) and p62/SQSTM1, which are essential components of the autophagy pathway. To study the role of the AhR in mediating PM-induced autophagy, we treated cells with α-NF or used an siRNA against AhR. Expression of LC3-ІІ induced by PM was decreased in a dose dependent manner by α-NF. Furthermore, knockdown of AhR with siAhR diminished PM-induced expression of LC3-ІІ and p62. Together, these results suggest that inhibition of the AhR decreases PM-induced autophagy. We confirmed these results using the autophagy-inhibitors BAF and 3-MA. Taken together, our results indicate that exposure to PM induces autophagy via the AhR in HaCaT keratinocytes.

Ochratoxin A causes mitochondrial dysfunction, apoptotic and autophagic cell death and also induces mitochondrial biogenesis in human gastric epithelium cells

Ochratoxin A (OTA) is a common natural contaminant found in human and animal food worldwide. Our previous work has shown that OTA can cause oxidative DNA damage, G₂ arrest and malignant transformation of human gastric epithelium (GES-1) cells. Mitochondria are considered to be target for the action of many cytotoxic agents. However, the role of mitochondria in the cytotoxicity of OTA remains unknown. The aim of this study is to explore the putative role of mitochondria on OTA cytotoxicity by analyzing mitochondrial changes in GES-1 cells. The results showed that OTA treatment (5, 10, 20 µM) for different times caused increases in the production of reactive oxygen species, and induced mitochondrial damage, shown by loss of mitochondrial membrane potential (ΔΨM), and decrease in cellular ATP concentration. Subsequently, the mitochondrial apoptotic pathway was activated, presented by increase of apoptotic rate and activation of apoptotic proteins. Autophagic cell death was also triggered, demonstrated by the conversion of light chain 3B (LC3B)-I to LC3B-II and elevated levels of green fluorescent protein-LC3 (GFP-LC3) puncta. Moreover, Parkin-dependent mitophagy was also activated presented by the colocalization of MitoTracker with LysoTracker or GFP-LC3 puncta. The inhibition of autophagy and mitophagy by inhibitors or siRNA attenuated the toxic effect of OTA on cell growth. Interestingly, OTA treatment also enhanced mitochondrial biogenesis confirmed by activation of AMPK/PGC-1α/TFAM pathway and promoted cell survival. Collectively, the effects of OTA on mitochondria of GES-1 cells are complex. OTA could cause mitochondrial function disturbance, apoptotic and autophagic cell death and also induce mitochondrial biogenesis.

Insights into autophagy machinery in cells related to skin diseases and strategies for therapeutic modulation

Autophagy, literally meaning "self-eating," is a highly conserved process that is part of the eukaryotic cell cycle. Morphologically, the double membrane contains vesicles with phagocytic components known as autophagosomes. Autophagy is often used as a cellular stress response and quality control mechanisms are used to maintain cell survival. Survival is facilitated by providing energy and metabolic precursors as well as removing damaged proteins or organelles. Moreover, autophagy refers to organelles fused together with part of the cell cytoplasm with a double or multi-membrane structure called phagosome. Research has demonstrated that autophagy is an important mediator of cell fate and has effects on inflammation, pathogen clearance, and antigen presentation. In recent years, studies discussing autophagy have increased in number. Nevertheless, only a small amount of research has considered the impact of autophagy on the pathogenesis of skin diseases. The skin is the largest organ of the body, with a surface area of around two square metre; it is the first line of defense against numerous environmental insults, including ultraviolet radiation, pathogens, mechanical stresses, and toxic chemicals. Autophagy is thought to be a vital modality for endogenous defenses against environmental derangements. This review provides an overview of autophagy machinery in keratinocytes, skin fibroblasts, melanocytes related to skin diseases as well as strategies for therapeutic modulation, for the future development of treatment for skin diseases.

ARID1A and CEBPα cooperatively inhibit UCA1 transcription in breast cancer

As one of the primary members of SWI/SNF chromatin remodeling complexes, ARID1A contains frequent loss-of-function mutations in many types of cancers. However, the molecular mechanisms underlying ARID1A deficiency in cancer biology remain to be investigated. Using breast cancer as a model, we report that silencing ARID1A significantly increased cellular proliferation and migration. Mechanistically, primarily functioning as a transcriptional repressor, loss of ARID1A profoundly alters histone modifications and the transcriptome. Notably, ARID1A inhibited the expression of a long non-coding RNA, UCA1, by regulating chromatin access of the transcription factor CEBPα. Restoration experiments showed that UCA1 mediates the functions of ARID1A that induces loss of cellular proliferation and migration. Together, our findings characterize ARID1A as a key tumor-suppressor gene in breast cancer through cooperation with CEBPα, and loss-of-function mutations of ARID1A activates UCA1.

Ochratoxin A induces cytoprotective autophagy via blocking AKT/mTOR signaling pathway in PK-15 cells

Ochratoxin A (OTA) could cause a variety of toxicological effects especially nephrotoxicity in animals and humans. Autophagy is a highly conserved metabolic process that plays an important role in the maintenance of cellular homeostasis under stress. However, the role of autophagy in OTA-induced nephrotoxicity is unknown. In the present study, we demonstrated that OTA treatment at 2.0-8.0 μM could increase cytotoxicity of PK-15 cells by inducing apoptosis as shown by the increased Annexin V/PI staining, increased caspase-3 and PARP cleavage and increased apoptotic nuclei. Meantime, autophagy was triggered when OTA was administrated, as indicated by markedly increased expressions of LC3-II, ATG5 and Beclin-1, accumulation of GFP-LC3 dots and increased double- or single-membrane vesicles. OTA treatment decreased p-AKT and p-mTOR activities, and OTA-induced autophagy was inhibited when insulin was applied. Furthermore, OTA treatments with autophagy inhibitors (3-methyladenine or chloroquine) or knockdown of autophagy-related genes (ATG5 or Beclin-1) resulted in significantly reduced autophagy level and enhanced cytotoxicity. In conclusion, OTA induces cytoprotective autophagy against its cytotoxicity and inactivation of AKT/mTOR axis plays a critical role in autophagy induction.

Effects of atorvastatin on autophagy in skeletal muscles of diabetic rats

AIMS/INTRODUCTION

Atorvastatin is usually used to decrease the amount of fatty substances in individuals with type 2 diabetes mellitus. However, it can cause side-effects, such as breakdown of skeletal muscle tissue. The present study focused on the effects of atorvastatin on autophagy of the skeletal muscles in diabetic rats.

MATERIALS AND METHODS

Diabetes in rats in the diabetic (D) and atorvastatin (T) groups was induced using streptozotocin (65 mg/kg, intraperitoneal injection). Next, rats in the T group were treated with atorvastatin (10 mg/kg/day, intragastric administration), whereas rats in the control and D groups were given water. Additionally, the rats in T and D groups were fed a high-fat and high-sugar diet for 10 weeks. Subsequently, the histopathological changes, and expression levels of microtubule-associated protein 1 light chain 3 (LC3)-I/-II and p62 in the skeletal muscle specimens in the three groups were analyzed.

RESULTS

Rats in the T group had reduced lipid droplets, cholesterol and low-density lipoprotein (P < 0.05) levels than those in the D group. Disordered atrophic myocytes, incrassated vascular walls and decreased cross-sectional area of type I fibers were found using hematoxylin-eosin and adenosine triphosphatase staining in the D and T groups. The messenger ribonucleic acid and protein levels of LC3-II and the LC3-II/LC3-I ratio were increased in the T group compared with those in the other groups (P < 0.05), whereas the protein level of p62 showed the opposite trend.

CONCLUSIONS

Atorvastatin enhanced the autophagy level of skeletal muscles to decrease lipid deposition, which possibly exacerbated myopathy.

The signaling involved in autophagy machinery in keratinocytes and therapeutic approaches for skin diseases

Autophagy is responsible for the lysosomal degradation of proteins, organelles, microorganisms and exogenous particles. Epidermis primarily consists of keratinocytes which functions as an extremely important barrier. Investigation on autophagy in keratinocytes has been continuously renewing, but is not so systematic due to the complexity of the autophagy machinery. Here we reviewed recent studies on the autophagy in keratinocyte with a focus on interplay between autophagy machinery and keratinocytes biology, and novel autophagy regulators identified in keratinocytes. In this review, we discussed the roles of autophagy in apoptosis, differentiation, immune response, survival and melanin metabolism, trying to reveal the possible involvement of autophagy in skin aging, skin disorders and skin color formation. Since autophagy routinely plays a double-edged sword role in various conditions, its functions in skin homeostasis and potential application as a therapeutic target for skin diseases remains to be clarified. Furthermore, more investigations are needed on optimizing designed strategies to inhibit or enhance autophagy for clinical efficacy.

Isoaaptamine Induces T-47D Cells Apoptosis and Autophagy via Oxidative Stress

Aaptos is a genus of marine sponge which belongs to Suberitidae and is distributed in tropical and subtropical oceans. Bioactivity-guided fractionation of Aaptos sp. methanolic extract resulted in the isolation of aaptamine, demethyloxyaaptamine, and isoaaptamine. The cytotoxic activity of the isolated compounds was evaluated revealing that isoaaptamine exhibited potent cytotoxic activity against breast cancer T-47D cells. In a concentration-dependent manner, isoaaptamine inhibited the growth of T-47D cells as indicated by short-(MTT) and long-term (colony formation) anti-proliferative assays. The cytotoxic effect of isoaaptamine was mediated through apoptosis as indicated by DNA ladder formation, caspase-7 activation, XIAP inhibition and PARP cleavage. Transmission electron microscopy and flow cytometric analysis using acridine orange dye indicated that isoaaptamine treatment could induce T-47D cells autophagy. Immunoblot assays demonstrated that isoaaptamine treatment significantly activated autophagy marker proteins such as type II LC-3. In addition, isoaaptamine treatment enhanced the activation of DNA damage (γH2AX) and ER stress-related proteins (IRE1 α and BiP). Moreover, the use of isoaaptamine resulted in a significant increase in the generation of reactive oxygen species (ROS) as well as in the disruption of mitochondrial membrane potential (MMP). The pretreatment of T-47D cells with an ROS scavenger, N-acetyl-l-cysteine (NAC), attenuated the apoptosis and MMP disruption induced by isoaaptamine up to 90%, and these effects were mediated by the disruption of nuclear factor erythroid 2-related factor 2 (Nrf 2)/p62 pathway. Taken together, these findings suggested that the cytotoxic effect of isoaaptamine is associated with the induction of apoptosis and autophagy through oxidative stress. Our data indicated that isoaaptamine represents an interesting drug lead in the war against breast cancer.

Toxicological effects of patulin mycotoxin on the mammalian system: an overview

The mycotoxin PAT (4-hydroxy-4H-furo[3,2c]pyran-2[6H]-one) is a secondary metabolic product of molds such as Penicillium, Aspergillus, and Byssochlamys species. PAT is a common contaminant of fruit and vegetable based products, most notably apples. Despite PAT's original discovery as an antibiotic, it has come under heavy scrutiny for its potential to impart negative health effects. Studies investigating these health effects have proved its toxic potential. PAT occurrence in the food commodities poses a serious threat and necessitates novel and cost-effective mitigation methods to remove it from food products. It also creates a demand to improve handling and food processing techniques. With this being the case, several studies have been devoted to understanding the key biological and chemical attributes of PAT. While past research has elucidated a great deal, PAT contamination continues to be a challenge for the food industry. Here, we review its influence within the mammalian system, including its regulation, incidences of experimental evidence of PAT toxicity, its interaction with intracellular components, and the effects of PAT induced systemic toxicity on vital organs. Finally, key areas where future PAT research should focus to best control the PAT contamination problem within the food industry have been addressed.

Ochratoxin A-induced autophagy in vitro and in vivo promotes porcine circovirus type 2 replication

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium. Porcine circovirus type 2 (PCV2) is recognized as the causative agent of porcine circovirus-associated diseases. Recently, we reported that low doses of OTA promoted PCV2 replication in vitro and in vivo, but the underlying mechanism needed further investigation. The present studies further confirmed OTA-induced PCV2 replication promotion as measured by cap protein expression, viral titer, viral DNA copies and the number of infected cells. Our studies also showed that OTA induced autophagy in PK-15 cells, as assessed by the markedly increased expression of microtubule-associated protein 1 light chain 3 (LC3)-II, autophagy-related protein 5 (ATG5), and Beclin-1 and the accumulation of green fluorescent protein (GFP)-LC3 dots. OTA induced complete autophagic flux, which was detected by monitoring p62 degradation and LC3-II turnover using immunoblotting. Inhibition of autophagy by 3-methylademine (3-MA) and chloroquine (CQ) significantly attenuated OTA-induced PCV2 replication promotion. The observed phenomenon was further confirmed by the knock-down of ATG5 or Beclin-1 by specific siRNA. Further studies showed that N-acetyl-L-cysteine (NAC), an ROS scavenger could block autophagy induced by OTA, indicating that ROS may be involved in the regulation of OTA-induced autophagy. Furthermore, we observed significant increases in OTA concentrations in lung, spleen, kidney, liver and inguinal lymph nodes (ILN) and bronchial lymph nodes (BLN) of pigs fed 75 and 150 μg/kg OTA compared with controls in vivo. Administration of 75 μg/kg OTA significantly increased PCV2 replication and autophagy in the lung, spleen, kidney and BLN of pigs. Taken together, it could be concluded that OTA-induced autophagy in vitro and in vivo promotes PCV2 replication.

In vitro antitumor activity of patulin on cervical and colorectal cancer cell lines

Background and Purpose:

Patulin is a mycotoxin produced by some molds, especially Aspergillus and Penicilium, and is responsible for mycotoxicosis in animals and humans.

There is still not very detailed data about the anti-cancer potency of patulin, but some reports demonstrated that it induces cellular apoptosis and toxicity.

Materials and Methods:

To determine the efficacy of patulin as a therapeutic strategy for cervical and colorectal cancers, we investigated its effects on HeLa,SW-48, and MRC-5 cell lines. Cell lines were exposed to various concentrations of patulin (i.e., 0.5, 1, 2, and 4 µM), then using methyl thiazolyl tetrazolium (MTT) and bromo-2′-deoxyuridine (BrdU) assays, the rates of apoptosis and cell viability were determined.

Results:

The obtained results showed a significant reduction in cell viability and apoptosis induction in a dose-dependent manner. Among all the cell lines, the highest growth inhibition rate was obtained at the 4 μM concentration of patulin.

Conclusion:

Our results suggested that patulin could significantly decrease tumor growth in human cervical and colorectal cancer models.

In vitro antitumor activity of patulin on cervical and colorectal cancer cell lines

BACKGROUND AND PURPOSE

Patulin is a mycotoxin produced by some molds, especially Aspergillus and Penicilium, and is responsible for mycotoxicosis in animals and humans.There is still not very detailed data about the anti-cancer potency of patulin, but some reports demonstrated that it induces cellular apoptosis and toxicity.

MATERIALS AND METHODS

To determine the efficacy of patulin as a therapeutic strategy for cervical and colorectal cancers, we investigated its effects on HeLa,SW-48, and MRC-5 cell lines. Cell lines were exposed to various concentrations of patulin (i.e., 0.5, 1, 2, and 4 µM), then using methyl thiazolyl tetrazolium (MTT) and bromo-2'-deoxyuridine (BrdU) assays, the rates of apoptosis and cell viability were determined.

RESULTS

The obtained results showed a significant reduction in cell viability and apoptosis induction in a dose-dependent manner. Among all the cell lines, the highest growth inhibition rate was obtained at the 4 μM concentration of patulin.

CONCLUSION

Our results suggested that patulin could significantly decrease tumor growth in human cervical and colorectal cancer models.

Graphene oxide quantum dots disrupt autophagic flux by inhibiting lysosome activity in GC-2 and TM4 cell lines

Graphene oxide quantum dots (GOQDs) have broad application prospects in many areas including bioimaging, drug delivery, DNA cleavage system, sensors and photocatalyst. Recently, increasing concerns have been raised about their biocompatibility, but studies about the effects of GOQDs on male reproductive system are still lacking. In this work, we explored the effects and molecular mechanisms of GOQDs on GC-2 and TM4 cells. We found autophagosome accumulation in GC-2 and TM4 cells after GOQDs treatment. Both LC3-II/LC3-I ratio and p62 levels increased, and the chloroquine-induced accumulation of LC3-II didn't enhance in the presence of GOQDs, which indicated that GOQDs blocked autophagic flux. Further studies found that the fusion between autophagosome and lysosome was not inhibited by GOQDs, but the proteolytic capacity of lysosome was weakened and both the expression and activity of cathepsin B reduced. Taken together, these results suggested that GOQDs blocked autophagic flux by decreasing the amount and enzymatic activity of cathepsin B and inhibiting lysosome proteolytic capacity in GC-2 and TM4 cells, which might have a potential hazard to male reproduction.

SH003 suppresses breast cancer growth by accumulating p62 in autolysosomes

Drug markets revisits herbal medicines, as historical usages address their therapeutic efficacies with less adverse effects. Moreover, herbal medicines save both cost and time in development. SH003, a modified version of traditional herbal medicine extracted from Astragalus membranaceus (Am), Angelica gigas (Ag), and Trichosanthes Kirilowii Maximowicz (Tk) with 1:1:1 ratio (w/w) has been revealed to inhibit tumor growth and metastasis on highly metastatic breast cancer cells, both in vivo and in vitro with no toxicity. Meanwhile, autophagy is imperative for maintenance cellular homeostasis, thereby playing critical roles in cancer progression. Inhibition of autophagy by pharmacological agents induces apoptotic cell death in cancer cells, resulting in cancer treatment. In this study, we demonstrate that SH003-induced autophagy via inhibiting STAT3 and mTOR results in an induction of lysosomal p62/SQSTM1 accumulation-mediated reactive oxygen species (ROS) generation and attenuates tumor growth. SH003 induced autophagosome and autolysosome formation by inhibiting activation of STAT3- and mTOR-mediated signaling pathways. However, SH003 blocked autophagy-mediated p62/SQSTM1 degradation through reducing of lysosomal proteases, Cathepsins, resulting in accumulation of p62/SQSTM1 in the lysosome. The accumulation of p62/SQSTM1 caused the increase of ROS, which resulted in the induction of apoptotic cell death. Therefore, we conclude that SH003 suppresses breast cancer growth by inducing autophagy. In addition, SH003-induced p62/SQSTM1 could function as an important mediator for ROS generation-dependent cell death suggesting that SH003 may be useful for treating breast cancer.

Cyclic AMP efflux inhibitors as potential therapeutic agents for leukemia

Apoptotic evasion is a hallmark of cancer. We propose that some cancers may evade cell death by regulating 3'-5'-cyclic adenosine monophosphate (cAMP), which is associated with pro-apoptotic signaling. We hypothesize that leukemic cells possess mechanisms that efflux cAMP from the cytoplasm, thus protecting them from apoptosis. Accordingly, cAMP efflux inhibition should result in: cAMP accumulation, activation of cAMP-dependent downstream signaling, viability loss, and apoptosis. We developed a novel assay to assess cAMP efflux and performed screens to identify inhibitors. In an acute myeloid leukemia (AML) model, several identified compounds reduced cAMP efflux, appropriately modulated pathways that are responsive to cAMP elevation (cAMP-responsive element-binding protein phosphorylation, and deactivation of Very Late Antigen-4 integrin), and induced mitochondrial depolarization and caspase activation. Blocking adenylyl cyclase activity was sufficient to reduce effects of the most potent compounds. These compounds also decreased cAMP efflux and viability of B-lineage acute lymphoblastic leukemia (B-ALL) cell lines and primary patient samples, but not of normal primary peripheral blood mononuclear cells. Our data suggest that cAMP efflux is a functional feature that could be therapeutically targeted in leukemia. Furthermore, because some of the identified drugs are currently used for treating other illnesses, this work creates an opportunity for repurposing.

Mycotoxins: cytotoxicity and biotransformation in animal cells

Mycotoxins are secondary metabolites produced by many microfungi. Hitherto, over 300 mycotoxins with diverse structures have been identified. They contaminate most cereals and feedstuffs, which threaten human and animal health by exerting acute, sub-acute and chronic toxicological effects, with some considered as carcinogens. Many mycotoxins at low concentrations are able to induce the expression of cytochrome P450 and other enzymes implicated in the biotransformation and metabolization of mycotoxins in vivo and in vitro. Mycotoxins and their metabolites elicit different cellular disorders and adverse effects such as oxidative stress, inhibition of translation, DNA damage and apoptosis in host cells, thus causing various kinds of cytotoxicities. In this review, we summarize the biotransformation of mycotoxins in animal cells by CYP450 isoforms and other enzymes, their altered expression under mycotoxin exposure, and recent progress in mycotoxin cytotoxicity in different cell lines. Furthermore, we try to generalize the molecular mechanisms of mycotoxin effects in human and animal cells.

Glutathione-S-transferase omega 1 (GSTO1-1) acts as mediator of signaling pathways involved in aflatoxin B1-induced apoptosis-autophagy crosstalk in macrophages

Aflatoxin B1 (AFB1) is the most toxic aflatoxin species and has been shown to be associated with specific as well as non-specific immune responses. In the present study, using murine macrophage Raw 264.7 cells as a model, we report that short exposure (6h) to AFB1 caused an increase in the cellular calcium pool in mitochondria, which in turn elevated reactive oxygen species (ROS)-mediated oxidative stress and led to loss of mitochondrial membrane potential and ultimately c-Jun N-terminal kinases (JNK)-mediated caspase-dependent cell death. On the contrary, longer exposure (12h) to AFB1 reduced JNK phosphorylation and cell death in macrophages. Measurement of autophagic flux demonstrated that autophagy induction through the canonical pathway was responsible for suppressing AFB1-induced apoptosis after 12h. As a detailed molecular mechanism, we found that the unfolded protein response (UPR) machinery was active at 12h post-exposure to AFB1 and induced cytoprotective autophagy as confirmed by determination of major autophagic markers. Inhibition of autophagy by Beclin-1 siRNA also resulted in JNK-mediated cell death. We further established that glutathione S transferase omega1-1 (GSTO1-1), a specific class of GST, was the responsible factor between apoptosis and autophagy crosstalk. Targeting of GSTO1-1 increased JNK-mediated apoptosis by 2-fold compared to the control, whereas autophagy rate was reduced. Thus, increased expression of GSTO1-1 was associated with increased protein glutathionylation, an important protein modification in response to cellular redox status.

Redox regulation of mitophagy in the lung during murine Staphylococcus aureus sepsis

Oxidative mitochondrial damage is closely linked to inflammation and cell death, but low levels of reactive oxygen and nitrogen species serve as signals that involve mitochondrial repair and resolution of inflammation. More specifically, cytoprotection relies on the elimination of damaged mitochondria by selective autophagy (mitophagy) during mitochondrial quality control. This aim of this study was to identify and localize mitophagy in the mouse lung as a potentially upregulatable redox response to Staphylococcus aureus sepsis. Fibrin clots loaded with S. aureus (1×10(7) CFU) were implanted abdominally into anesthetized C57BL/6 and B6.129X1-Nfe2l2tm1Ywk/J (Nrf2(-/-)) mice. At the time of implantation, mice were given vancomycin (6mg/kg) and fluid resuscitation. Mouse lungs were harvested at 0, 6, 24, and 48h for bronchoalveolar lavage (BAL), Western blot analysis, and qRT-PCR. To localize mitochondria with autophagy protein LC3, we used lung immunofluorescence staining in LC3-GFP transgenic mice. In C57BL/6 mice, sepsis-induced pulmonary inflammation was detected by significant increases in mRNA for the inflammatory markers IL-1β and TNF-α at 6 and 24h, respectively. BAL cell count and protein also increased. Sepsis suppressed lung Beclin-1 protein, but not mRNA, suggesting activation of canonical autophagy. Notably sepsis also increased the LC3-II autophagosome marker, as well as the lung׳s noncanonical autophagy pathway as evidenced by loss of p62, a redox-regulated scaffolding protein of the autophagosome. In LC3-GFP mouse lungs, immunofluorescence staining showed colocalization of LC3-II to mitochondria, mainly in type 2 epithelium and alveolar macrophages. In contrast, marked accumulation of p62, as well as attenuation of LC3-II in Nrf2-knockout mice supported an overall decrease in autophagic turnover. The downregulation of canonical autophagy during sepsis may contribute to lung inflammation, whereas the switch to noncanonical autophagy selectively removes damaged mitochondria and accompanies tissue repair and cell survival. Furthermore, mitophagy in the alveolar region appears to depend on activation of Nrf2. Thus, efforts to promote mitophagy may be a useful therapeutic adjunct for acute lung injury in sepsis.

Autophagy and senescence, stress responses induced by the DNA-damaging mycotoxin alternariol

The mycotoxin alternariol (AOH), a frequent contaminant in fruit and grain, is known to induce cellular stress responses such as reactive oxygen production, DNA damage and cell cycle arrest. Cellular stress is often connected to autophagy, and we employed the RAW264.7 macrophage model to test the hypothesis that AOH induces autophagy. Indeed, AOH treatment led to a massive increase in acidic vacuoles often observed upon autophagy induction. Moreover, expression of the autophagy marker LC3 was markedly increased and there was a strong accumulation of LC3-positive puncta. Increased autophagic activity was verified biochemically by measuring the degradation rate of long-lived proteins. Furthermore, AOH induced expression of Sestrin2 and phosphorylation of AMPK as well as reduced phosphorylation of mTOR and S6 kinase, common mediators of signaling pathways involved in autophagy. Transmission electron microscopy analyzes of AOH treated cells not only clearly displayed structures associated with autophagy such as autophagosomes and autolysosomes, but also the appearance of lamellar bodies. Prolonged AOH treatment resulted in changed cell morphology from round into more star-shaped as well as increased β-galactosidase activity. This suggests that the cells eventually entered senescence. In conclusion, our data identify here AOH as an inducer of both autophagy and senescence. These effects are suggested to be to be linked to AOH-induced DSB (via a reported effect on topoisomerase activity), resulting in an activation of p53 and the Sestrin2-AMPK-mTOR-S6K signaling pathway.