Gene of the month: BECN1

The Role of Regulatory Cell Death in Vitiligo

Vitiligo is one of the common chronic autoimmune skin diseases in clinic, which is characterized by localized or generalized depigmentation and seriously affects the physical and mental health of patients. At present, the pathogenesis of vitiligo is not clear; mainly, heredity, autoimmunity, oxidative stress, melanocyte (MC) self-destruction, and the destruction, death, or dysfunction of MCs caused by various reasons are always the core of vitiligo. Regulatory cell death (RCD) is an active and orderly death mode of cells regulated by genes, which widely exists in various life activities, plays a pivotal role in maintaining the homeostasis of the organism, and is closely related to the occurrence and development of many diseases. With the deepening of the research and understanding of RCD, people gradually found that there are many different forms of RCD in the lesions and perilesional skin of vitiligo patients, such as apoptosis, autophagy, pyroptosis, ferroptosis, and so on. Different cell death modes have different mechanisms in vitiligo, and different RCDs can interact and regulate each other. In this article, the mechanism related to RCD in the pathogenesis of vitiligo is reviewed, which provides new ideas for exploring the pathogenesis and targeted treatment of vitiligo.

Autoimmunity and Carcinogenesis: Their Relationship under the Umbrella of Autophagy

The immune system and autophagy share a functional relationship. Both innate and adaptive immune responses involve autophagy and, depending on the disease’s origin and pathophysiology, it may have a detrimental or positive role on autoimmune disorders. As a “double-edged sword” in tumors, autophagy can either facilitate or impede tumor growth. The autophagy regulatory network that influences tumor progression and treatment resistance is dependent on cell and tissue types and tumor stages. The connection between autoimmunity and carcinogenesis has not been sufficiently explored in past studies. As a crucial mechanism between the two phenomena, autophagy may play a substantial role, though the specifics remain unclear. Several autophagy modifiers have demonstrated beneficial effects in models of autoimmune disease, emphasizing their therapeutic potential as treatments for autoimmune disorders. The function of autophagy in the tumor microenvironment and immune cells is the subject of intensive study. The objective of this review is to investigate the role of autophagy in the simultaneous genesis of autoimmunity and malignancy, shedding light on both sides of the issue. We believe our work will assist in the organization of current understanding in the field and promote additional research on this urgent and crucial topic.

Cryptosporidium parvum maintains intracellular survival by activating the host cellular EGFR-PI3K/Akt signaling pathway

Autophagy is a critical cellular mechanism in helping infected cells remove intracellular pathogens and is countered by pathogens maintaining intracellular survival by regulating autophagy through the manipulation of the host cellular signal transduction pathway. Cryptosporidium parvum is a zoonotic intracellular but extracytoplasmic protozoon that causes diarrhea in infants and young children worldwide. However, it is still unclear how Cryptosporidium adapts to intracellular survival. In the present study, we demonstrated that C. parvum could activate the EGFR-PI3K/Akt signaling pathway to promote intracellular survival in HCT-8 cells. The western blot results showed that C. parvum induced EGFR and Akt phosphorylation in HCT-8 cells. The EGFR inhibitor AG1478 decreased EGFR and Akt phosphorylation, and the PI3K inhibitor LY294002 impaired Akt phosphorylation induced by C. parvum in HCT-8 cells. Inhibition of EGFR or Akt decreased the number of intracellular parasites. Second, low-dose infection of C. parvum triggered complete autophagy and enhanced autophagic flux in HCT-8 cells. The expressions of mTOR and p62 were decreased, and the expressions of LC3 and Beclin1 were increased in C. parvum-infected HCT-8 cells. Transfection with siBeclin1 or siATG7 reduced LC3 accumulation, while lysosome inhibitor E64d+pepA increased LC3 accumulation induced by C. parvum in HCT-8 cells. Intracellular parasite proliferation was decreased when treated with autophagy inducer rapamycin, whereas autophagy inhibitor 3-MA, E64d+pep A, siBeclin1 or siATG7 increased intracellular parasites. Third, C. parvum inhibited autophagy killing to promote its own intracellular survival by activating EGFR-Akt signaling pathway. The EGFR inhibitor AG1478 enhanced autophagic flux, and Akt inhibitor IV increased LC3 accumulation and inhibited C. parvum proliferation in HCT-8 cells. Akt inhibitor IV-inhibited C. parvum proliferation was attenuated by E64d+pepA. In summary, C. parvum could maintain intracellular survival by inhibiting autophagy via EGFR-PI3K/Akt pathway. These results revealed a new mechanism for the interaction of C. parvum with host cells.

Epigenetic and post-translational modifications in autophagy: biological functions and therapeutic targets

Autophagy is a conserved lysosomal degradation pathway where cellular components are dynamically degraded and re-processed to maintain physical homeostasis. However, the physiological effect of autophagy appears to be multifaced. On the one hand, autophagy functions as a cytoprotective mechanism, protecting against multiple diseases, especially tumor, cardiovascular disorders, and neurodegenerative and infectious disease. Conversely, autophagy may also play a detrimental role via pro-survival effects on cancer cells or cell-killing effects on normal body cells. During disorder onset and progression, the expression levels of autophagy-related regulators and proteins encoded by autophagy-related genes (ATGs) are abnormally regulated, giving rise to imbalanced autophagy flux. However, the detailed mechanisms and molecular events of this process are quite complex. Epigenetic, including DNA methylation, histone modifications and miRNAs, and post-translational modifications, including ubiquitination, phosphorylation and acetylation, precisely manipulate gene expression and protein function, and are strongly correlated with the occurrence and development of multiple diseases. There is substantial evidence that autophagy-relevant regulators and machineries are subjected to epigenetic and post-translational modulation, resulting in alterations in autophagy levels, which subsequently induces disease or affects the therapeutic effectiveness to agents. In this review, we focus on the regulatory mechanisms mediated by epigenetic and post-translational modifications in disease-related autophagy to unveil potential therapeutic targets. In addition, the effect of autophagy on the therapeutic effectiveness of epigenetic drugs or drugs targeting post-translational modification have also been discussed, providing insights into the combination with autophagy activators or inhibitors in the treatment of clinical diseases.

Electroacupuncture Preconditioning Alleviates Lipopolysaccharides-Induced Acute Lung Injury by Downregulating LC3-II/I and Beclin 1 Expression

Our study aimed to investigate the effect of electroacupuncture pretreatment on the inflammatory response and expression levels of LC3-II/I and Beclin 1 using a model of lipopolysaccharide (LPS)-induced acute lung injury (ALI). Eighteen male Sprague-Dawley (SD) rats were randomly divided into three groups: normal control group (NC, n = 6), LSP modeling group (LM, n = 6), and electroacupuncture group (EA, n = 6). Rats in the EA group received electroacupuncture pretreatment at bilateral Zusanli (ST36) and Chize (LU5) points for five days (30 min each time daily, frequency; 3 Hz/15 Hz, intensity; 1 mA). Rats in the EA and LM groups were then injected with 5 mg/kg LPS (Beijing, Solarbio Company, concentration; 5 mg/mL) through the tail vein, while those in the NC group were injected with 5 mg/kg saline. The animals were sacrificed six hours after LPS or saline injection through cervical vertebrae by dislocation under deep anesthesia. Orbital blood was collected for the analysis of serum inflammatory factors including interleukin-1β (IL-1β) and transforming growth factor-β (TGF-β). The lower left lung was excised, stained with hematoxylin-eosin (HE), and subjected to histopathological analysis. The mRNA and protein expression of Beclin 1 and LC3 II/I in the lower right lung tissues were detected via RT-qPCR and Western blot analyses, respectively. The results showed that lung injury score was significantly higher in the LM group than that of the NC group (P < 0.01) and EA group (P < 0.01). The IL-1β contents were significantly decreased in the EA group (P < 0.01) than in the LM group. In contrast, the GF-β contents were increased in the EA group significantly when compared with the LM group (P < 0.01). RT-qPCR and Western blot detection showed that the relative gene expression of LC3-II/I and Beclin 1 was significantly lower in the EA group than in the LM group (P < 0.01). However, the relative protein expression level of LC3-II/I and Beclin 1 was slightly lower in the EA group than the in LM group (P > 0.05). These results show that electroacupuncture pretreatment reduces the inflammatory response in ALI and can protect lung tissue by inhibiting the gene and protein expression levels of LC3-II/I and Beclin 1.

The functional mechanism of bone marrow-derived mesenchymal stem cells in the treatment of animal models with Alzheimer's disease: crosstalk between autophagy and apoptosis

The transplantation of bone marrow-derived mesenchymal stem cells (BMMSCs) alleviates neuropathology and improves cognitive deficits in animal models with Alzheimer's disease. However, the underlying mechanism remains undefined. Based on meta-analysis and comprehensive review, high-profile studies support the theory that transplanted BMMSCs activate autophagy, as evidenced by the expression levels of signal molecules such as Beclin-1, Atg5, LC3-II, and mTOR. Functional autophagy mitigates neuronal apoptosis, which is reflected by the alterations of IAPs, Bcl-2, caspase-3, and so forth. Moreover, the transplantation of BMMSCs can decrease aberrant amyloid-beta peptides as well as tau aggregates, inhibit neuroinflammation, and stimulate synaptogenesis. There is a signal crosstalk between autophagy and apoptosis, which may be regulated to produce synergistic effect on the preconditioning of stem cells. Forasmuch, the therapeutic effect of transplanted BMMSCs can be enhanced by autophagy and/or apoptosis modulators.

Effects of Herb-Partitioned Moxibustion on Autophagy and Immune Activity in the Colon Tissue of Rats with Crohn’s Disease

Objective

To investigate the mechanism of action of herb-partitioned moxibustion on CD from the perspective of autophagy and immunity.

Methods

The expression of microtubule-associated protein LC3II and SQSTM1/p62 in the colon tissues was detected by immunohistochemistry. Western blot was used to detect the expression of autophagic and immune-related proteins in the colon, such as LC3II, SQSTM1/p62, Beclin1, ATG16L1, NOD2, IRGM, IL-1β, IL-17, and TNF-β. mRNA levels of immune factors, such as IL-1β, IL-17, and TNF-β, and autophagy signaling molecules, such as PI3KC, AKT1, LKB1, and mTOR, were detected by RT-qPCR.

Results

Herb-partitioned moxibustion reduced the protein levels of ATG16L1, NOD2, IRGM, LC3II, and Beclin1 (P < 0.01) and both the protein and mRNA levels of IL-1β, IL-17, and TNF-β in CD rats (P < 0.01 or P < 0.05), and it also increased the expression of SQSTM1/p62 protein (P < 0.01). The modulatory effects of herb-partitioned moxibustion on ATG16L1, NOD2, IRGM, LC3II, TNF-β, and IL-17 protein and IL-1β protein and mRNA were better than those of mesalazine (P < 0.01 or P < 0.05). Herb-partitioned moxibustion also reduced colon PI3KC, AKT1, and LKB1 mRNA expressions in CD rats (P < 0.01 or P < 0.05) and increased mTOR protein expression (P < 0.05). And the modulatory effect of herb-partitioned moxibustion on AKT1 mRNA was better than that of mesalazine (P < 0.05).

Conclusion

Herb-partitioned moxibustion may inhibit excessively activated autophagy and modulate the expression of immune-related factors by regulating the LKB1-mTOR-PI3KC signal transduction networks, thereby alleviating intestinal inflammation in CD rats.

Emerging Role of Autophagy in the Development and Progression of Oral Squamous Cell Carcinoma

Autophagy is a cellular catabolic process, which is characterized by degradation of damaged proteins and organelles needed to supply the cell with essential nutrients. At basal levels, autophagy is important to maintain cellular homeostasis and development. It is also a stress responsive process that allows the cells to survive when subjected to stressful conditions such as nutrient deprivation. Autophagy has been implicated in many pathologies including cancer. It is well established that autophagy plays a dual role in different cancer types. There is emerging role of autophagy in oral squamous cell carcinoma (OSCC) development and progression. This review will focus on the role played by autophagy in relation to different aspects of cancer progression and discuss recent studies exploring the role of autophagy in OSCC. It will further discuss potential therapeutic approaches to target autophagy in OSCC.

Serum DJ-1 Is a Biomarker of Colorectal Cancer and DJ-1 Activates Mitophagy to Promote Colorectal Cancer Progression

Simple Summary

Colorectal cancer is common cancer, and currently used serum markers for detecting colorectal cancer lack excellent diagnostic accuracy. In the present study, we collected matched tumor and adjacent normal tissues and serum from patients and cancer cells to demonstrate the clinical value of DJ-1 in colorectal cancer and the role of DJ-1-induced mitophagy in colorectal cancer progression. Our data indicate that DJ-1 might be clinically valuable as serum and tissue biomarkers for predicting the TNM (tumor-node-metastasis) stage in colorectal cancer patients. Besides, DJ-1 knockdown enhanced intracellular reactive oxygen species generation and damaged mitochondrial accumulation and mitophagy inhibition in metastatic colorectal adenocarcinoma cells. Since DJ-1-induced mitophagy promotes tumor progression, DJ-1 inhibition is a potential therapeutic strategy for colorectal cancer treatment.

Abstract

Colorectal cancer is the second most common cancer and the third cancer-associated death in Taiwan. Currently used serum markers for detecting colorectal cancer lack excellent diagnostic accuracy, which results in colorectal cancer being often recognized too late for successful therapy. Mitophagy is the selective autophagic degradation of damaged or excessive mitochondria. DJ-1 is an antioxidant protein that attenuates oxidative stress and maintains mitochondrial quality through activating mitophagy. Mitophagy activation contributes to anti-cancer drug resistance. However, the role of DJ-1-induced mitophagy in colorectal cancer progression remains unclear. In the present study, we collected matched tumor and adjacent normal tissues and serum from patients and cancer cells to demonstrate the clinical value and physiological function of DJ-1 in colorectal cancer. We found that DJ-1 increased in tumor tissues and serum; it was positively correlated with TNM (tumor-node-metastasis) stages of colorectal cancer patients. Through stable knockdown DJ-1 expression in metastatic colorectal adenocarcinoma cells SW620, DJ-1 knockdown inhibited cancer cell survival, migration, and colony formation. In SW620 cells, DJ-1 knockdown induced an incomplete autophagic response that did not affect ATP production; DJ-1 knockdown enhanced intracellular reactive oxygen species generation and damaged mitochondrial accumulation and mitophagy inhibition. It suggests that DJ-1 knockdown inhibits mitophagy that causes metastatic colorectal adenocarcinoma cells to be unable to remove damaged mitochondria and further enhance cancer cell apoptosis. Our data indicate that DJ-1 might be clinically valuable as serum and tissue biomarkers for predicting the TNM stage in colorectal cancer patients. Since DJ-1-induced mitophagy promotes tumor progression, DJ-1 inhibition is a potential therapeutic strategy for colorectal cancer treatment.

Sestrin2 and Beclin1 levels in Polycystic Ovary Syndrome

Background

Sestrin2 and beclin1 are two newly found proteins that have essential roles in autophagy. This study attempted to evaluate the plasma concentrations of sestrin2 and beclin1 in women with polycystic ovary syndrome (PCOS) and healthy controls and to explore the clinical value of these proteins as novel biomarkers for PCOS.

Methods

In this case‐control study, plasma levels of sestrin2 and beclin1, fasting blood sugar (FBS), lipid profile, insulin, and androgens were evaluated in 63 women (31 patients and 32 controls). Sestrin2 and beclin1 levels were determined using enzyme‐linked immunosorbent assay (ELISA). Descriptive statistics, correlation coefficients, logistic regression, and ROC curve analyses were used in this study.

Results

Plasma sestrin2 levels of the subjects with PCOS (40.74 [24.39–257.70]) were significantly lower than those of healthy subjects (255.78 [25.46–528.66]; p‐value = 0.040). ROC curve analysis showed that a cutoff value of 420.5 ng/L had an appropriate sensitivity (83.87%) and specificity (46.88%) for discriminating individuals with and without PCOS, with the area under the curve (95% CI) of 0.648 (0.518 to 0.764), p = 0.036. There were no statistically significant differences between the two groups concerning plasma levels of beclin1, biochemical parameters, blood pressure, and anthropometric features.

Conclusion

Our findings highlight the dysregulation of sestrin2 as a marker of autophagy in PCOS and its potential usefulness as a novel biomarker for PCOS. Further research is needed to better understand the role of this protein in the pathophysiology of PCOS and its value as a diagnostic tool for the evaluation of PCOS patients.

EVA1A Plays an Important Role by Regulating Autophagy in Physiological and Pathological Processes

Eva-1 homolog A (EVA1A) is regarded as TMEM166 (transmembrane protein 166) or FAM176A (family with sequence similarity 176) and a lysosome and endoplasmic reticulum-associated protein involved in regulating autophagy and apoptosis. EVA1A regulates embryonic neurogenesis, cardiac remodeling, islet alpha-cell functions, acute liver failure, and hepatitis B virus replication. However, the related mechanisms are not fully clear. Autophagy is a process in which cells transfer pathogens, abnormal proteins and organelles to lysosomes for degradation. It plays an important role in various physiological and pathological processes, including cancer, aging, neurodegeneration, infection, heart disease, development, cell differentiation and nutritional starvation. Recently, there are many studies on the important role of EVA1A in many physiological and pathological processes by regulating autophagy. However, the related molecular mechanisms need further study. Therefore, we summarize the above-mentioned researches about the role of EVA1A in physiological and pathological processes through regulating autophagy in order to provide theoretical basis for future researches.

MiR-493 Induces Cytotoxic Autophagy in Prostate Cancer Cells through Regulation on PHLPP2

BACKGROUND

MiR-493 promotes the proliferation of prostate cancer (PC) cells by targeting PHLPP2. We aimed to explore the relationship between miR-493 and autophagy in PC.

METHODS

qRT-PCR and western blotting were used to determine the mRNA levels and protein expression of miR-493, PHLPP2, autophagy gene BECN1 and ATG7 in PC cells. The autophagy gene expression was determined after PC cells transfected with miR-493 precursor or PHLPP2 precursor. Corresponding changes of autophagy phenotype and PC cell function were also studied.

RESULTS

The mRNA levels and protein expression of miR-493, PHLPP2, BECN1 and ATG7 in PC cells were significantly decreased in PC cells. Overexpression of miR-493 or PHLPP2 markedly upregulated the expression levels of BECN1 and ATG7 in PC cells. Overexpression of miR-493 and PHLPP2 markedly promoted autophagy, and inhibited the invasion and cloning formation of PC cells.

CONCLUSION

MiR-493 is a potent inducer of cytotoxic autophagy that leads to prostate cancer inhibition by regulating on PHLPP2.

The Roles of Beclin 1 Expression in Gastric Cancer: A Marker for Carcinogenesis, Aggressive Behaviors and Favorable Prognosis, and a Target of Gene Therapy

Beclin 1 is encoded by Becn1, and plays a role in tumorigenesis, neurodegeneration, apoptosis and autophagy. Here, the aggressive phenotypes and relevant proteins were examined after Beclin 1 expression was altered in gastric cancer cells. We also observed the effects of Beclin 1 on gastric carcinogenesis using Becn1 knockout mice. Finally, clinicopathological significances of Beclin 1 expression were analyzed using meta- and bioinformatics analyses. Becn1 overexpression was found to inhibit proliferation, glucose metabolism, migration and invasion of gastric cancer cells, whereas its knockdown caused the opposite effects. Beclin 1 suppressed the tumor growth by decreasing proliferation and increasing apoptosis. The heterozygous abrogation of Becn1 in gastric pit, parietal and chief cells could not cause any epithelial lesion. Beclin 1-mediated chemoresistance was closely linked to the autophagy, Bax underexpression, and the overexpression of Bcl-2, LRP1, MDR1, and ING5. Bioinformatics analysis showed higher Becn1 mRNA expression in intestinal- than diffuse-type carcinomas (P<0.05), and in male than female gastric cancer patients (P<0.05). Becn1 hyperexpression was positively associated with both overall and progression-free survival rates of the cancer patients (P<0.05). Meta-analysis showed that down-regulated Beclin 1 expression in gastric cancer was positively with lymph node metastasis, TNM staging, dedifferentiation and poor prognosis (P<0.05). Becn1-related signal pathways in gastric cancer included prostate, lung, renal, colorectal, endometrial and thyroid cancers, glioma, and leukemia, the metabolism of amino acid, lipid and sugar, and some signal pathways of insulin, MAPK, TRL, VEGF, JAK-STAT, chemokine, p53, lysosome, peroxidome and ubiquitin-mediated protein degradation (P<0.05). These suggested that Beclin 1 might be considered as a potential marker of gastric carcinogenesis, aggressiveness and prognostic prediction, and as a target of gene therapy in gastric cancer.

Electroacupuncture Improves Motor Symptoms of Parkinson's Disease and Promotes Neuronal Autophagy Activity in Mouse Brain

Autophagic defects are a hallmark of neurodegenerative disorders, such as Parkinson's disorder (PD). Enhancing autophagy to remove impaired mitochondria and toxic protein aggregation is an essential component of PD treatment. In particular, activation of autophagy confers neuroprotection in cellular and preclinical models of neurodegenerative diseases. In this study, we investigated the therapeutic mechanisms of electroacupuncture (EA) treatment in mice with established PD and evaluated the relationship between EA, autophagy, and different neurons in the mouse brain. We report that EA improves PD motor symptoms in mice and enhances (1) autophagy initiation (increased Beclin 1), (2) autophagosome biogenesis (increased Atg5, Atg7, Atg9A, Atg12, Atg16L, Atg3, and LC3-II), (3) autophagy flux/substrate degradation (decreased p62), and (4) mitophagy (increased PINK1 and DJ-1) in neurons of the substantia nigra, striatum, hippocampus, and cortex (affected brain areas of PD, Huntington disease, and Alzheimer's disease). EA enhances autophagy initiation, autophagosome biogenesis, mitophagy, and autophagy flux/substrate degradation in certain brain areas. Our findings are the first to show that EA regulates neuronal autophagy and suggest that this convenient, inexpensive treatment has exciting therapeutic potential in neurodegenerative disorders.

LncRNA GAS8-AS1 Inhibits Ovarian Cancer Progression Through Activating Beclin1-Mediated Autophagy

Background

Early detection and diagnosis of ovarian cancer (OC) is complicated due to the concealment of the ovarian anatomical position and the lack of clinical manifestations and specific indicators of early OC. Therefore, it is urgent to study the pathogenesis of OC, especially the molecular mechanism.

Results

LncRNA GAS8-AS1 was decreased in OC tissues and cell lines, and high expression of GAS8-AS1 indicated a higher 5-year survival rate of OC patients. Overexpression of GAS8-AS1 suppressed growth of OC cells, while deletion of GAS8-AS1 promoted the progression of OC cells. Further data indicated GAS8-AS1 activated autophagy in OC cells. Functional experiments showed that 3-MA removed the inhibitory effect of GAS8-AS1 in OC cells. On the contrary, Rapamycin reversed the promoting effect of GAS8-AS1 in OC cells. Furthermore, GAS8-AS1 bound with Beclin1 and promoted its expression, and silencing of Beclin1 reversed the inhibitory role of GAS8-AS1 in OC progression. In vivo tumorigenesis assay showed GAS8-AS1 suppressed OC progression and activated Beclin1 mediated autophagy.

Conclusion

Our study suggested GAS8-AS1 inhibited OC progression by activating autophagy via binding with Beclin1, and GAS8-AS1 might be a potential therapeutic target for OC clinical treatment.

The anti-tumor agent, Dp44mT, promotes nuclear translocation of TFEB via inhibition of the AMPK-mTORC1 axis

Di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT) and its analogues are potent anti-cancer agents through their ability to target lysosomes. Considering this, it was important to understand the mechanisms involved in the Dp44mT-mediated induction of autophagy and the role of 5'-adenosine monophosphate-activated protein kinase (AMPK) as a critical autophagic regulator. As such, this investigation examined AMPK's role in the regulation of the transcription factor EB (TFEB), which transcribes genes involved in autophagy and lysosome biosynthesis. For the first time, this study demonstrated that Dp44mT induces translocation of TFEB to the nucleus. Furthermore, Dp44mT-mediated nuclear translocation of TFEB was AMPK-dependent. Considering that: (1) the mammalian target of rapamycin complex 1 (mTORC1) plays an important role in the regulation of TFEB; and (2) that AMPK is a known regulator of mTORC1, this study also elucidated the mechanisms through which Dp44mT regulates nuclear translocation of TFEB via AMPK. Silencing AMPK led to increased mTOR phosphorylation, that activates mTORC1. Since Dp44mT inhibits mTORC1 in an AMPK-dependent manner through raptor phosphorylation, Dp44mT is demonstrated to regulate TFEB translocation through dual mechanisms: AMPK activation, which inhibits mTOR, and inhibition of mTORC1 via phosphorylation of raptor. Collectively, Dp44mT-mediated activation of AMPK plays a crucial role in lysosomal biogenesis and TFEB function. As Dp44mT potently chelates copper and iron that are crucial for tumor growth, these studies provide insight into the regulatory mechanisms involved in intracellular clearance and energy metabolism that occur upon alterations in metal ion homeostasis.

Evaluation of autophagy-related genes in Egyptian systemic lupus erythematosus patients

Disturbances in autophagy are known to be implicated in autoimmune disorders. Many studies have connected polymorphisms in autophagy-related gene 5 (ATG-5) to systemic lupus erythematosus (SLE). Our aim was the determination of the expression level of ATG-5, Beclin-1 and microtubule-associated protein-light chain 3 (LC-3) in Egyptian SLE patients to investigate the impact of disturbances in autophagy genes on the incidence and progression of the disease. Also, we investigated the incidence of single nucleotide polymorphism (SNP) rs573775 in ATG-5 gene among Egyptian SLE patients. Our results showed that the mean levels of Beclin-1, LC-3 and interleukin (IL)-10 transcripts were significantly higher in SLE patients compared to healthy controls. The previous transcripts were positively correlated with SLE Disease Activity Index (SLEDAI). Beclin-1 and LC-3 transcripts were negatively correlated to complement component 3 (C3) levels. Only LC-3 transcripts were negatively correlated to complement component 4 (C4). The rs573775 SNP of ATG-5 with the variant allele was significantly associated with disease susceptibility, conferring a higher risk of SLE development. This variant allele was more prevalent in patients below 30 years, patients with anemia and in patients with anti-double-stranded DNA (dsDNA), confirming the essential role of ATG-5 polymorphism in the susceptibility of Egyptian patients to SLE.

SETX (senataxin), the helicase mutated in AOA2 and ALS4, functions in autophagy regulation

SETX (senataxin) is an RNA/DNA helicase that has been implicated in transcriptional regulation and the DNA damage response through resolution of R-loop structures. Mutations in SETX result in either of two distinct neurodegenerative disorders. SETX dominant mutations result in a juvenile form of amyotrophic lateral sclerosis (ALS) called ALS4, whereas recessive mutations are responsible for ataxia called ataxia with oculomotor apraxia type 2 (AOA2). How mutations in the same protein can lead to different phenotypes is still unclear. To elucidate AOA2 disease mechanisms, we first examined gene expression changes following SETX depletion. We observed the effects on both transcription and RNA processing, but surprisingly observed decreased R-loop accumulation in SETX-depleted cells. Importantly, we discovered a strong connection between SETX and the macroautophagy/autophagy pathway, reflecting a direct effect on transcription of autophagy genes. We show that SETX depletion inhibits the progression of autophagy, leading to an accumulation of ubiquitinated proteins, decreased ability to clear protein aggregates, as well as mitochondrial defects. Analysis of AOA2 patient fibroblasts also revealed a perturbation of the autophagy pathway. Our work has thus identified a novel function for SETX in the regulation of autophagy, whose modulation may have a therapeutic impact for AOA2.Abbreviations: 3'READS: 3' region extraction and deep sequencing; ACTB: actin beta; ALS4: amyotrophic lateral sclerosis type 4; AOA2: ataxia with oculomotor apraxia type 2; APA: alternative polyadenylation; AS: alternative splicing; ATG7: autophagy-related 7; ATP6V0D2: ATPase H+ transporting V0 subunit D2; BAF: bafilomycin A₁; BECN1: beclin 1; ChIP: chromatin IP; Chloro: chloroquine; CPT: camptothecin; DDR: DNA damage response; DNMT1: DNA methyltransferase 1; DRIP: DNA/RNA IP; DSBs: double strand breaks; EBs: embryoid bodies; FTD: frontotemporal dementia; GABARAP: GABA type A receptor-associated protein; GO: gene ontology; HR: homologous recombination; HTT: huntingtin; IF: immunofluorescence; IP: immunoprecipitation; iPSCs: induced pluripotent stem cells; KD: knockdown; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MN: motor neuron; MTORC1: mechanistic target of rapamycin kinase complex 1; PASS: PolyA Site Supporting; PFA: paraformaldehyde; RNAPII: RNA polymerase II; SCA: spinocerebellar ataxia; SETX: senataxin; SMA: spinal muscular atrophy; SMN1: survival of motor neuron 1, telomeric; SQSTM1/p62: sequestosome 1; TFEB: transcription factor EB; TSS: transcription start site; TTS: transcription termination site; ULK1: unc-51 like autophagy activating kinase 1; WB: western blot; WIPI2: WD repeat domain, phosphoinositide interacting 2; XRN2: 5'-3' exoribonuclease 2.

BECN1 modulates hematopoietic stem cells by targeting Caspase-3-GSDME-mediated pyroptosis

Hematopoietic stem cells (HSCs) maintain the blood system throughout the lifespan. However, the molecular mechanism maintaining HSC character remains not fully understood. In this study, we observed that the targeted deletion of Becn1 disrupts the blood system and impairs the reconstitution capacity of HSCs. Interestingly, Becn1 deletion did not lead to dysfunction of autophagy in HSCs, indicating a non-classical role of BECN1 in regulating HSCs function. While we observed the increase of Caspase-3-GSDME-mediated pyroptosis in Becn1 deficient hematopoietic stem and progenitor cells. Forced expression of the full-length GSDME compromises the function of HSCs. In brief, we identified a novel role of Becn1 in modulating HSCs by regulating pyroptosis, but not through autophagy. This study provides a new link between BECN1-Caspase-3-GSDME signaling and HSC maintenance.

Galantamine Inhibits Aβ1-42-Induced Neurotoxicity by Enhancing α7nAChR Expression as a Cargo Carrier for LC3 Binding and Aβ1-42 Engulfment During Autophagic Degradation

Despite Alzheimer's disease (AD) being the most common neurodegenerative disorder worldwide, no FDA-approved disease-modifying treatments have been approved for this condition since 2003. Neuronal-type alpha7 nicotinic acetylcholine receptors (α7nAChRs) play an essential role in cognitive functions, binding with extracellular β-amyloid (Aβ plaques) and inhibiting Aβ-induced neurotoxicity. α7nAChRs are impaired early in the course of AD; drugs targeting α7nAChRs are being hotly pursued as a treatment of AD. Encenicline, a partial selective agonist of α7nAChR and modulator of acetylcholine, failed in phase III trials because of gastrointestinal side effects. We, therefore, evaluated the efficacy of galantamine, a positive allosteric modulator at α7nAChRs and an acetylcholinesterase inhibitor, that has been used since 2000 as first-line treatment of mild-to-moderate dementia. This study highlights an important new benefit with galantamine. We found that galantamine inhibits Aβ1-42-induced apoptosis by activating the JNK signaling pathway, thus enhancing α7nAChR expression, and also inhibits the Akt pathway, which further increases autophagosome biogenesis and autophagy. These effects can be reproduced by α7nAChR overexpression in the absence of galantamine. Importantly, the α7 subunit protein sequence of α7nAChRs contains 3 LC3-interacting regions; our immunoprecipitation data show that α7 binds with the autophagosomal marker protein LC3. This is the first report to provide evidence showing that the cell surface receptor α7nAChR acts as a cargo carrier for LC3 binding for Aβ1-42 sequestration to autophagosomes, suggesting a novel mechanism for the neuroprotective efficacy of galantamine in AD.

Regulation of autophagy and apoptosis by Dp44mT-mediated activation of AMPK in pancreatic cancer cells

Upon activation, the 5'-adenosine monophosphate-activated protein kinase (AMPK) increases catabolism, while inhibiting anabolism. The anti-cancer agent, di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT), activates AMPK in multiple tumor cell-types (Biochim. Biophys Acta 2016;1863:2916-2933). This acts as an initial cell "rescue response" after iron-depletion mediated by Dp44mT. Considering Dp44mT-mediated AMPK activation, the role of AMPK on Dp44mT cytotoxicity was examined. Dp44mT increased the p-AMPK/AMPK ratio in multiple tumor cell-types over short (24 h) and longer (72 h) incubations. Notably, Dp44mT was more effective in inhibiting tumor cell proliferation after AMPK silencing, potentially due to the loss of AMPK-mediated metabolic plasticity that protects cells against Dp44mT cytotoxicity. The silencing of AMPK-increased cellular cholesterol and stabilized lysosomes against Dp44mT-mediated lysosomal membrane permeabilization. This was substantiated by studies demonstrating that the cholesterol-depleting agent, methyl-β-cyclodextrin (MβCD), restores Dp44mT-mediated lysosomal membrane permeabilization in AMPK silenced cells. The increased levels of cholesterol after AMPK silencing were independent of the ability of AMPK to inhibit the rate-limiting step of cholesterol synthesis via the inactivating phosphorylation of 3-hydroxy-3-methylglutaryl CoA reductase (HMGCR) at Ser872. In fact, Dp44mT did not increase phosphorylation of HMGCR at (Ser872), but decreased total HMGCR expression similarly in both the presence or absence of AMPK silencing. Dp44mT was demonstrated to increase autophagic initiation after AMPK silencing via an AMPK- and Beclin-1-independent mechanism. Further, there was increased cleaved caspase 3 and cleaved PARP after incubation of AMPK silenced cells with Dp44mT. Overall, AMPK silencing promotes Dp44mT anti-proliferative activity, suggesting a role for AMPK in rescuing its cytotoxicity by inhibiting autophagy and also apoptosis.

Celastrol Inhibits Dopaminergic Neuronal Death of Parkinson's Disease through Activating Mitophagy

Parkinson’s disease (PD) is a neurodegenerative disease, which is associated with mitochondrial dysfunction and abnormal protein accumulation. No treatment can stop or slow PD. Autophagy inhibits neuronal death by removing damaged mitochondria and abnormal protein aggregations. Celastrol is a triterpene with antioxidant and anti-inflammatory effects. Up until now, no reports have shown that celastrol improves PD motor symptoms. In this study, we used PD cell and mouse models to evaluate the therapeutic efficacy and mechanism of celastrol. In the substantia nigra, we found lower levels of autophagic activity in patients with sporadic PD as compared to healthy controls. In neurons, celastrol enhances autophagy, autophagosome biogenesis (Beclin 1↑, Ambra1↑, Vps34↑, Atg7↑, Atg12↑, and LC3-II↑), and mitophagy (PINK1↑, DJ-1↑, and LRRK2↓), and these might be associated with MPAK signaling pathways. In the PD cell model, celastrol reduces MPP⁺-induced dopaminergic neuronal death, mitochondrial membrane depolarization, and ATP reduction. In the PD mouse model, celastrol suppresses motor symptoms and neurodegeneration in the substantia nigra and striatum and enhances mitophagy (PINK1↑ and DJ-1↑) in the striatum. Using MPP⁺ to induce mitochondrial damage in neurons, we found celastrol controls mitochondrial quality by sequestering impaired mitochondria into autophagosomes for degradation. This is the first report to show that celastrol exerts neuroprotection in PD by activating mitophagy to degrade impaired mitochondria and further inhibit dopaminergic neuronal apoptosis. Celastrol may help to prevent and treat PD.

circHIPK3 promotes oxaliplatin-resistance in colorectal cancer through autophagy by sponging miR-637

BACKGROUND

Resistance to oxaliplatin-based chemotherapy is a major cause of recurrence in colorectal cancer (CRC) patients. There is increasing evidence indicating that circHIPK3 is involved in the development and progression of tumours. However, little is known about the potential role of circHIPK3 in CRC chemotherapy and its molecular mechanisms in chemoresistance also remain unclear.

METHODS

Quantitative real-time PCR was performed to detect circHIPK3 expression in tissues of 2 cohorts of CRC patients who received oxaliplatin-based chemotherapy. The chemoresistant effects of circHIPK3 were assessed by cell viability, apoptosis, and autophagy assays. The relationship between circHIPK3, miR-637, and STAT3 mRNA was confirmed by biotinylated RNA pull-down, luciferase reporter, and western blot assays.

FINDINGS

In the pilot study, increased circHIPK3 expression was observed in chemoresistant CRC patients. Functional assays showed that circHIPK3 promoted oxaliplatin resistance, which was dependent on inhibition of autophagy. Mechanistically, circHIPK3 sponged miR-637 to promote STAT3 expression, thereby activating the downstream Bcl-2/beclin1 signalling pathway. A clinical cohort study showed that circHIPK3 was upregulated in tissues from recurrent CRC patients and correlated with tumour size, regional lymph node metastasis, distant metastasis, and survival.

INTERPRETATION

circHIPK3 functions as a chemoresistant gene in CRC cells by targeting the miR-637/STAT3/Bcl-2/beclin1 axis and might be a prognostic predictor for CRC patients who receive oxaliplatin-based chemotherapy.

FUNDING

National Natural Science Foundation of China (81301506), Shandong Medical and Health Technology Development Project(2018WSB20002), Shandong Key Research and Development Program (2016GSF201122), Natural Science Foundation of Shandong Province (ZR2017MH044), and Jinan Science and Technology Development Plan(201805084, 201805003).

Proanthocyanidin-Rich Fractions from Red Rice Extract Enhance TNF-α-Induced Cell Death and Suppress Invasion of Human Lung Adenocarcinoma Cell A549

Tumor necrosis factor-alpha (TNF-α) plays a key role in promoting tumor progression, such as stimulation of cell proliferation and metastasis via activation of NF-κB and AP-1. The proanthocyanidin-rich fraction obtained from red rice (PRFR) has been reported for its anti-tumor effects in cancer cells. This study investigated the molecular mechanisms associated with PRFR on cell survival and metastasis of TNF-α-induced A549 human lung adenocarcinoma. Notably, PRFR enhanced TNF-α-induced A549 cell death when compared with PRFP alone and caused a G0-G1 cell cycle arrest. Although, PRFR alone enhanced cell apoptosis, the combination treatment induced the cells that had been enhanced with PRFR and TNF-α to apoptosis that was less than PRFR alone and displayed a partial effect on caspase-8 activation and PARP cleavage. By using the autophagy inhibitor; 3-MA attenuated the effect of how PRFR enhanced TNF-α-induced cell death. This indicates that PRFR not only enhanced TNF-α-induced A549 cell death by apoptotic pathway, but also by induction autophagy. Moreover, PRFR also inhibited TNF-α-induced A549 cell invasion. This effect was associated with PRFR suppressed the TNF-α-induced level of expression for survival, proliferation, and invasive proteins. This was due to reduce of MAPKs, Akt, NF-κB, and AP-1 activation. Taken together, our results suggest that TNF-α-induced A549 cell survival and invasion are attenuated by PRFR through the suppression of the MAPKs, Akt, AP-1, and NF-κB signaling pathways.

A Comprehensive Review of Autophagy and Its Various Roles in Infectious, Non-Infectious, and Lifestyle Diseases: Current Knowledge and Prospects for Disease Prevention, Novel Drug Design, and Therapy

Autophagy (self-eating) is a conserved cellular degradation process that plays important roles in maintaining homeostasis and preventing nutritional, metabolic, and infection-mediated stresses. Autophagy dysfunction can have various pathological consequences, including tumor progression, pathogen hyper-virulence, and neurodegeneration. This review describes the mechanisms of autophagy and its associations with other cell death mechanisms, including apoptosis, necrosis, necroptosis, and autosis. Autophagy has both positive and negative roles in infection, cancer, neural development, metabolism, cardiovascular health, immunity, and iron homeostasis. Genetic defects in autophagy can have pathological consequences, such as static childhood encephalopathy with neurodegeneration in adulthood, Crohn's disease, hereditary spastic paraparesis, Danon disease, X-linked myopathy with excessive autophagy, and sporadic inclusion body myositis. Further studies on the process of autophagy in different microbial infections could help to design and develop novel therapeutic strategies against important pathogenic microbes. This review on the progress and prospects of autophagy research describes various activators and suppressors, which could be used to design novel intervention strategies against numerous diseases and develop therapeutic drugs to protect human and animal health.

Chlorogenic Acid Alleviates Thiram-Induced Tibial Dyschondroplasia by Modulating Caspases, BECN1 Expression and ECM Degradation

Chlorogenic acid (CGA) is a widely applied traditional Chinese medicine ingredient which can be used for the treatment of osteoporosis. In this experiment, we investigated the potential therapeutic effect of chlorogenic acid on thiram-induced tibial dyschondroplasia (TD) and explored the underlying mechanisms that have been rarely mentioned by others yet. Performance indicator analysis and tibial parameter analysis showed that CGA exhibited a definite positive effect on thiram-induced TD chickens. In order to further explore the mechanisms underlying the positive actions of CGA, apoptotic, autophagic genes and MMPs involved in matrix mineralization of growth plate were evaluated in this study. The results showed that CGA decreased the expression of pro-apoptotic genes caspases-3 and caspases-9, leading to the reduction of apoptotic cells accumulated in growth plate. In addition, CGA also increased the level of BECN1, an important gene involved in autophagy, which benefits the survival of abnormal cells. Furthermore, CGA also increased the expression of MMP-9, MMP-10, and MMP-13, which can directly affect the ossification of bones. Altogether, these results demonstrate that CGA possesses a positive therapeutic effect on thiram-induced TD via modulating the expression of caspases and BECN1 and regulating the degradation of ECM (extracellular matrix).

The relationship between autophagy and the immune system and its applications for tumor immunotherapy

Autophagy is a genetically well-controlled cellular process that is tightly controlled by a set of core genes, including the family of autophagy-related genes (ATG). Autophagy is a “double-edged sword” in tumors. It can promote or suppress tumor development, which depends on the cell and tissue types and the stages of tumor. At present, tumor immunotherapy is a promising treatment strategy against tumors. Recent studies have shown that autophagy significantly controls immune responses by modulating the functions of immune cells and the production of cytokines. Conversely, some cytokines and immune cells have a great effect on the function of autophagy. Therapies aiming at autophagy to enhance the immune responses and anti-tumor effects of immunotherapy have become the prospective strategy, with enhanced antigen presentation and higher sensitivity to CTLs. However, the induction of autophagy may also benefit tumor cells escape from immune surveillance and result in intrinsic resistance against anti-tumor immunotherapy. Increasing studies have proven the optimal use of either ATG inducers or inhibitors can restrain tumor growth and progression by enhancing anti-tumor immune responses and overcoming the anti-tumor immune resistance in combination with several immunotherapeutic strategies, indicating that induction or inhibition of autophagy might show us a prospective therapeutic strategy when combined with immunotherapy. In this article, the possible mechanisms of autophagy regulating immune system, and the potential applications of autophagy in tumor immunotherapy will be discussed.

New compound ChlA-F induces autophagy-dependent anti-cancer effect via upregulating Sestrin-2 in human bladder cancer

ChlA-F is a novel conformation-derivative of Cheliensisin A, styryl-lactone isolates that show potent anti-tumor potential in vivo and vitro. However, the anti-cancer activity and its potential mechanisms underlying ChlA-F action have never been explored. In the present study, we evaluated the potency of ChlA-F on autophagy-mediated anchorage-independent growth inhibition in human high-grade invasive bladder cancer (BC) cells. We found that ChlA-F treatment significantly inhibited anchorage-independent growth of human BC cells by inducing autophagy in a Sestrin-2 (SESN2)-dependent fashion. Our results revealed that ChlA-F treatment specifically induced SESN2 expression via increasing its transcription and mRNA stability. On one hand, ChlA-F treatment markedly attenuated Dicer protein abundance, in turn abolishing miR-27a maturation and further relieving miR-27a binding directly to SESN2 mRNA 3'UTR, thereby promoting SESN2 mRNA stabilization. On the other hand, ChlA-F treatment promoted Sp1 abundance and consequently mediated SESN2 transcription. These results demonstrate that its activation of the autophagic pathway through specifically promoting SESN2 expression mediates the anti-cancer effect of ChlA-F, which offers insights into the novel anti-cancer effect of ChlA-F on BC, as well as providing therapeutic alternatives against human BC.

Expression of c-Myc and Beclin-1 in skin of rats after burn

This study aimed to investigate the expression features of Beclin-1 and c-Myc in the skin burn of rats. A total of 48 Sprague-Dawley (SD) rats were randomly divided into the normal group (n=12), the 3-day burn group (n=12), the 5-day burn group (n=12) and the 7-day burn group (n=12). Except for the normal group, the rat models of burn were established in the other three groups, burn wounds were given routine dressing change, and rats were sacrificed at 3, 5 and 7 days after modeling to collect materials. Then, immunohistochemistry was applied to detect the expression of c-Myc and Beclin-1. The expression levels of c-Myc protein and Beclin-1 protein were measured via western blotting. The expression levels of c-Myc messenger ribonucleic acid (mRNA) and Beclin-1 mRNA were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In comparison with the normal group, three burn groups had significantly increased the expression of c-Myc and Beclin-1, and the differences were statistically significant (P<0.05). Beclin-1 expression in the 5-day burn group was obviously higher than those in the 3 and 7-day burn groups, and the differences were of statistical significance (P<0.05). The expression of c-Myc in the 7-day burn group was overtly higher than those in the 3 and 5-day burn groups, and the differences showed statistical significance (P<0.05). The expression of Beclin-1 and c-Myc in post-burn skin tissues were gradually increased, with the Beclin-1 expression level reaching the peak on the 5th day after burn, and the expression level of c-Myc was the highest on the 7th day after burn.

Attenuation of everolimus-induced cytotoxicity by a protective autophagic pathway involving ERK activation in renal cell carcinoma cells

Aim

The mammalian target of rapamycin (mTOR) pathway is a critical target for cancer treatment and the mTOR inhibitor everolimus (RAD001) has been approved for treatment of renal cell carcinoma (RCC). However, the limited efficacy of RAD001 has led to the development of drug resistance. Autophagy is closely related to cell survival and death, which may be activated under RAD001 stimulation. The aim of the present study was to identify the underlying mechanisms of RAD001 resistance in RCC cells through cytoprotective autophagy involving activation of the extracellular signal-regulated kinase (ERK) pathway.

Methods and results:

RAD001 strongly induced autophagy of RCC cells in a dose- and time-dependent manner, as confirmed by Western blot analysis. Importantly, suppression of autophagy by the pharmacological inhibitor chloroquine effectively enhanced RAD001-induced apoptotic cytotoxicity, as demonstrated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Western blot analysis, indicating a cytoprotective role for RAD001-induced autophagy. In addition, as was shown by the MTT assay, flow cytometry, and Western blot analysis, RAD001 robustly activated ERK, but not c-Jun N-terminal kinase and p38. Activation of ERK was inhibited by the pharmacological inhibitor selumetinib (AZD6244), which effectively promoted RAD001-induced cell death. Moreover, employing AZD6244 markedly attenuated RAD001-induced autophagy and enhanced RAD001-induced apoptosis, which play a central role in RAD001-induced cell death. Furthermore, RAD001-induced autophagy is regulated by ERK-mediated phosphorylation of Beclin-1 and B-cell lymphoma 2, as confirmed by Western blot analysis.

Conclusion

These results suggest that RAD001-induced autophagy involves activation of the ERK, which may impair cytotoxicity of RAD001 in RCC cells. Thus, inhibition of the activation of ERK pathway-mediated autophagy may be useful to overcome chemoresistance to RAD001.

TRIM50 regulates Beclin 1 proautophagic activity

Autophagy is a catabolic process needed for maintaining cell viability and homeostasis in response to numerous stress conditions. Emerging evidence indicates that the ubiquitin system has a major role in this process. TRIMs, an E3 ligase protein family, contribute to selective autophagy acting as receptors and regulators of the autophagy proteins recognizing endogenous or exogenous targets through intermediary autophagic tags, such as ubiquitin. Here we report that TRIM50 fosters the initiation phase of starvation-induced autophagy and associates with Beclin1, a central component of autophagy initiation complex. We show that TRIM50, via the RING domain, ubiquitinates Beclin 1 in a K63-dependent manner enhancing its binding with ULK1 and autophagy activity. Finally, we found that the Lys-372 residue of TRIM50, critical for its own acetylation, is necessary for its E3 ligase activity that governs Beclin1 ubiquitination. Our study expands the roles of TRIMs in regulating selective autophagy, revealing an acetylation-ubiquitination dependent control for autophagy modulation.

Autophagy: novel applications of nonsteroidal anti-inflammatory drugs for primary cancer

In eukaryotic cells, autophagy is a process associated with programmed cell death. During this process, cytoplasmic proteins and organelles are engulfed by double-membrane autophagosomes, which then fuse with lysosomes to form autolysosomes. These autolysosomes then degrade their contents to recycle the cellular components. Autophagy has been implicated in a wide variety of physiological and pathological processes that are closely related to tumorigenesis. In recent years, an increasing number of studies have indicated that nonsteroidal anti-inflammatory drugs, such as celecoxib, meloxicam, sulindac, aspirin, sildenafil, rofecoxib, and sodium salicylate, have diverse effects in cancer that are mediated by the autophagy pathway. These nonsteroidal anti-inflammatory drugs can modulate tumor autophagy through the PI3K/Akt/mTOR, MAPK/ERK1/2, P53/DRAM, AMPK/mTOR, Bip/GRP78, CHOP/ GADD153, and HGF/MET signaling pathways and inhibit lysosome function, leading to p53-dependent G1 cell-cycle arrest. In this review, we summarize the research progress in autophagy induced by nonsteroidal anti-inflammatory drugs and the molecular mechanisms of autophagy in cancer cells to provide a reference for the potential benefits of nonsteroidal anti-inflammatory drugs in cancer chemotherapy.

Targeting LC3 and Beclin-1 autophagy genes suppresses proliferation, survival, migration and invasion by inhibition of Cyclin-D1 and uPAR/Integrin β1/ Src signaling in triple negative breast cancer cells

Autophagy is a catabolic process for degrading dysfunctional proteins and organelles, and closely associated with cancer cell survival under therapeutic, metabolic stress, hypoxia, starvation and lack of growth factors, contributing to resistance to therapies. However, the role of autophagy in breast cancer cells is not well understood. In the present study, we investigated the role of autophagy in highly aggressive and metastatic triple negative breast cancer (TNBC) and non-metastatic breast cancer cells and demonstrated that the knockdown of autophagy-related genes (LC3 and Beclin-1) inhibited autophagy and significantly suppressed cell proliferation, colony formation, migration/invasion and induced apoptosis in MDA-MB-231 and BT-549 TNBC cells. Knockdown of LC3 and Beclin-1 led to inhibition of multiple proto-oncogenic signaling pathways, including cyclin D1, uPAR/integrin-β1/Src, and PARP1. In conclusion, our study suggests that LC3 and Beclin-1 are required for cell proliferation, survival, migration and invasion, and may contribute to tumor growth and progression of highly aggressive and metastatic TNBC cells and therapeutic targeting of autophagy genes may be a potential therapeutic strategy for TNBC in breast cancer.

Regulation of the Tumor-Suppressor BECLIN 1 by Distinct Ubiquitination Cascades

Autophagy contributes to cellular homeostasis through the degradation of various intracellular targets such as proteins, organelles and microbes. This relates autophagy to various diseases such as infections, neurodegenerative diseases and cancer. A central component of the autophagy machinery is the class III phosphatidylinositol 3-kinase (PI3K-III) complex, which generates the signaling lipid phosphatidylinositol 3-phosphate (PtdIns3P). The catalytic subunit of this complex is the lipid-kinase VPS34, which associates with the membrane-targeting factor VPS15 as well as the multivalent adaptor protein BECLIN 1. A growing list of regulatory proteins binds to BECLIN 1 and modulates the activity of the PI3K-III complex. Here we discuss the regulation of BECLIN 1 by several different types of ubiquitination, resulting in distinct polyubiquitin chain linkages catalyzed by a set of E3 ligases. This contribution is part of the Special Issue “Ubiquitin System”.

Aristolochic Acid-Induced Autophagy Promotes Epithelial-to-Myofibroblast Transition in Human Renal Proximal Tubule Epithelial Cells

Autophagy plays an essential role in cellular homeostasis in kidney. Previous studies have found that aristolochic acid (AA) can induce autophagy of renal tubular epithelial cells and epithelial-to-myofibroblast transition (EMT). However, the relationship between AA-induced autophagy and EMT is unclear. Our results showed that, after AA stimulation, the appearance of autophagy preceded EMT. Autophagy of HKC cells began to increase gradually from the 3rd hour, reached the peak at 12th hour, and then weakened gradually until 36th hour; the EMT process of HKC continued to increase from 6th hour to 36th hour after AA stimulation. The enhancement of autophagy using autophagy inducers, rapamycin or serum-free medium, led to an aggravation of EMT and upregulated expression of fibronectin, a component of extracellular matrix, in AA-treated HKC cells. In contrast, the inhibition of autophagy by autophagy inhibitor, 3-methyladenine, or by knockdown of Beclin 1 led to an attenuation of EMT and downregulated expression of fibronectin in AA-treated HKC cells. Taken together, our study suggests that, after AA stimulation, two types of cell responses of HKC cells, autophagy and EMT, will successively appear, and autophagy can promote EMT of HKC.

Monitoring Autophagy Immunohistochemically and Ultrastructurally during Human Head and Neck Carcinogenesis. Relationship with the DNA Damage Response Pathway

Autophagy is a catabolic process that preserves cellular homeostasis. Its exact role during carcinogenesis is not completely defined. Specifically in head and neck cancer, such information from clinical settings that comprise the whole spectrum of human carcinogenesis is very limited. Towards this direction, we examined the in situ status of the autophagy-related factors, Beclin-1, microtubule-associated protein 1 light chain 3, member B (LC3B) and sequestosome 1/p62 (p62) in clinical material covering all histopathological stages of human head and neck carcinogenesis. This material is unique as each panel of lesions is derived from the same patient and moreover we have previously assessed it for the DNA damage response (DDR) activation status. Since Beclin-1, LC3B and p62 reflect the nucleation, elongation and degradation stages of autophagy, respectively, their combined immunohistochemical (IHC) expression profiles could grossly mirror the autophagic flux. This experimental approach was further corroborated by ultrastructural analysis, applying transmission electron microscopy (TEM). The observed Beclin-1/LC3B/p62 IHC patterns, obtained from serial sections analysis, along with TEM findings are suggestive of a declined authophagic activity in preneoplastic lesions that was restored in full blown cancers. Correlating these findings with DDR status in the same pathological stages are indicative of: (i) an antitumor function of autophagy in support to that of DDR, possibly through energy deprivation in preneoplastic stages, thus preventing incipient cancer cells from evolving; and (ii) a tumor-supporting role in the cancerous stage.

Mechanisms of autophagy induction by sex steroids in bovine mammary epithelial cells

In dairy cattle, mammary gland involution serves to remodel the secretory tissue and occurs in a period of overlap between mammogenic stimulation caused by the next developing pregnancy and tissue regression induced by milk stasis. At this time, high concentrations of 17β-oestradiol (E2) and progesterone (P4) support the regeneration of the mammary tissue, as well as enhance autophagy, a cellular process induced in response to stressful conditions for energy generation and homeostasis maintenance. This study aimed to elucidate the mechanisms of autophagy induction by E2 and P4 using an in vitro model of involution based on 20-fold reduction of FBS content (from 10% to 0.5%) in the culture medium of BME-UV1 bovine mammary epithelial cells (MECs). Real-time RT-PCR, Western blot and EMSA analyses demonstrated that addition of E2 and P4 caused a genomic effect in BME-UV1 cells, stimulating the expression of autophagy-related genes (ATGs): BECN1, ATG5, LC3B and their corresponding proteins. Furthermore, knockdown of oestrogen receptor (ERα) and experiments with the use of oestrogen and progesterone antagonists (4-hydroxytamoxifen and RU-486, respectively) demonstrated that the observed genomic effect is mediated by steroid receptors. Finally, both steroids were shown to form complexes with beclin1 and regulate Bcl-2 phosphorylation, indicating that an indirect, non-genomic effect of E2 and P4 may also contribute to autophagy induction in bovine MECs.

Metabolic interactions between cysteamine and epigallocatechin gallate

Phase II clinical trials indicate that the combination of cysteamine plus epigallocatechin gallate (EGCG) is effective against cystic fibrosis in patients bearing the most frequent etiological mutation (CFTRΔF508). Here, we investigated the interaction between both agents on cultured respiratory epithelia cells from normal and CFTRΔF508-mutated donors. We observed that the combination of both agents affected metabolic circuits (and in particular the tricarboxylic acid cycle) in a unique way and that cysteamine plus EGCG reduced cytoplasmic protein acetylation more than each of the 2 components alone. In a cell-free system, protein cross-linking activity of EGCG was suppressed by cysteamine. Finally, EGCG was able to enhance the conversion of cysteamine into taurine in metabolic flux experiments. Altogether, these results indicate that multiple pharmacological interactions occur between cysteamine and EGCG, suggesting that they contribute to the unique synergy of both agents in restoring the function of mutated CFTRΔF508.

Autophagy function and its relationship to pathology, clinical applications, drug metabolism and toxicity

Autophagy is a cellular process that facilitates nutrient turnover and removal of expended macromolecules and organelles to maintain homeostasis. The recycling of cytosolic macromolecules and damaged organelles by autophagosomes occurs through the lysosomal degradation pathway. Autophagy can also be upregulated as a prosurvival pathway in response to stress stimuli such as starvation, hypoxia or cell damage. Over the last two decades, there has been a surge in research revealing the basic molecular mechanisms of autophagy in mammalian cells. A corollary of an advanced understanding of autophagy has been a concurrent expansion of research into understanding autophagic function and dysfunction in pathology. Recent studies have revealed a pivotal role for autophagy in drug toxicity, and for utilizing autophagic components as diagnostic markers and therapeutic targets in treating disease and cancer. In this review, advances in understanding the molecular basis of mammalian autophagy, methods used to induce and evaluate autophagy, and the diverse interactions between autophagy and drug toxicity, disease progression and carcinogenesis are discussed. Copyright © 2016 John Wiley & Sons, Ltd.

Prediction of post translation modifications at the contact site between Anaplasma phagocytophilum and human host during autophagosome induction using a bioinformatic approach

Autophagy is crucial for maintaining physiological homeostasis, but its role in infectious diseases is not yet adequately understood. The binding of Anaplasma translocated substrate-1 (ATS1) to the human Beclin1 (BECN1) protein is responsible for the modulation of autophagy pathway. ATS1-BECN1 is a novel type of interaction that facilitates Anaplasma phagocytophilum proliferation, leading to intracellular infection via autophagosome induction and segregation from the lysosome. Currently, there is no report of post translational modifications (PTMs) of BECN1 or cross-talk required for ATS-BECN1 complex formation. Prediction/modeling of the cross-talk between phosphorylation and other PTMs (O-β-glycosylation, sumoylation, methylation and palmitoylation) has been attempted in this study, which might be responsible for regulating function after the interaction of ATS1 with BECN1. PTMs were predicted computationally and mapped onto the interface of the docked ATS1-BECN1 complex. Results show that BECN1 phosphorylation at five residues (Thr91, Ser93, Ser96, Thr141 and Ser234), the interplay with O-β-glycosylation at three sites (Thr91, Ser93 and Ser96) with ATS1 may be crucial for attachment and, hence, infection. No other PTM site at the BECN1 interface was predicted to associate with ATS1. These findings may have significant clinical implications for understanding the etiology of Anaplasma infection and for therapeutic studies.

Prognostic relevance of autophagy-related markers LC3, p62/sequestosome 1, Beclin-1 and ULK1 in colorectal cancer patients with respect to KRAS mutational status

Background

Autophagy is a cellular pathway that regulates transportation of cytoplasmic macromolecules and organelles to lysosomes for degradation. Autophagy is involved in both tumorigenesis and tumour suppression. Here we investigated the potential prognostic value of the autophagy-related proteins Beclin-1, p62, LC3 and uncoordinated (UNC) 51-like kinase 1 (ULK1) in a cohort of colorectal cancer (CRC) specimens.

Methods

In this study, we analysed the immunoexpression of the autophagy-related proteins p62, LC3, Beclin-1 and ULK1 in 127 CRC patients with known KRAS mutational status and detailed clinical follow-up.

Results

Survival analysis of p62 staining showed a significant correlation of cytoplasmic (not nuclear) p62 expression with a favourable tumour-specific overall survival (OS). The prognostic power of cytoplasmic p62 was found in the KRAS-mutated subgroup but was lost in the KRAS wildtype subgroup. Survival analysis of Beclin-1 staining did not show an association with OS in the complete cohort. LC3 overexpression demonstrated a slight, though not significant, association with decreased OS. Upon stratifying cases by KRAS mutational status, nuclear (not cytoplasmic) Beclin-1 staining was associated with a significantly decreased OS in the KRAS-mutated subgroup but not in the KRAS wildtype CRCs. In addition, LC3 overexpression was significantly associated with decreased OS in the KRAS-mutated CRC subgroup. ULK1 expression was not correlated to survival.

Conclusions

Immunohistochemical analyses of LC3, p62 and Beclin-1 may constitute promising novel prognostic markers in CRC, especially in KRAS-mutated CRCs. This strategy might help in identifying high-risk patients who would benefit from autophagy-related anticancer drugs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12957-016-0946-x) contains supplementary material, which is available to authorized users.

Effect of autophagy-related beclin1 on sensitivity of cisplatin-resistant ovarian cancer cells to chemotherapeutic agents

The purpose of the study was to determine the effects of autophagy related gene Beclin1 at different levels of expression on the sensitivity of cisplatin-resistant ovarian cancer cells (SKOV3/DDP) to different chemotherapeutics. In pSUPER-Beclin1 transfected cells, real-time fluorescence quantitative RT-PCR and Western blot analysis showed that expression was significantly inhibited. Flow cytometry revealed that the mean fluorescence intensity (MDC), reflecting autophagy, and cells in the G0/G1 phase were markedly reduced. When compared with the blank control group, inhibition of Beclin1 expression in SKOV3/DDP cells not only increased the rate of apoptosis following treatment with chemotherapeutics, but also increased the sensitivity. These findings suggest that Beclin1 expression plays an important role in chemotherapeutic agent-induced death of SKOV3/DDP cells. Inhibition of autophagy related gene Beclin1 expression in SKOV3/DDP cells may increase the rate of apoptosis and elevate the sensitivity to chemotherapeutics.

Breast cancer cell line MDA-MB-231 miRNA profile expression after BIK interference: BIK involvement in autophagy

B-cell lymphoma 2 (BCL2)-interacting killer (apoptosis inducing) (BIK) has been proposed as a tumor suppressor in diverse types of cancers. However, BIK's overexpression in breast cancer (BC) and in non-small lung cancer cells (NSCLCs), associated with a poor prognosis, suggests its participation in tumor progression. In this study, we evaluated the global expression pattern of microRNAs (miRNAs), messenger RNA (mRNA) expression changes in autophagy, and autophagic flux after BIK interference. BIK gene expression was silenced by small interfering RNA (siRNA) in BC cell MDA-MB-231, and BIK interference efficiency was tested by real-time PCR and by Western blotting. BIK expression levels decreased by 75 ± 18 % in the presence of 600 nM siRNA, resulting in the abolishment of BIK expression by 94 ± 30 %. BIK interference resulted in the overexpression of 17 miRNAs that, according to the DIANA-miRPath v3.0 database, are mainly implied in the control of cell signaling, gene expression, and autophagy. The autophagy array revealed downregulation of transcripts which participate in autophagy, and their interactome revealed a complex network, where hepatocyte growth factor-regulated tyrosine kinase substrate (HGS), α-synuclein (SNCA), unc-51-like autophagy activating kinase 1/2 (ULK1/2), and mitogen-activated protein kinase 3 (MAPK3) were shown to be signaling hubs. LC3-II expression-an autophagy marker-was increased by 169 ± 25 % after BIK interference, which indicates the involvement of BIK in autophagy. Altogether, our results indicate-for the first time-that BIK controls the expression of miRNAs, as well as the autophagic flux in MDA-MB-231 cells.

Autophagy in colorectal cancer: An important switch from physiology to pathology

Colorectal cancer (CRC) remains a leading cause of cancer death in both men and women worldwide. Among the factors and mechanisms that are involved in the multifactorial etiology of CRC, autophagy is an important transformational switch that occurs when a cell shifts from normal to malignant. In recent years, multiple hypotheses have been considered regarding the autophagy mechanisms that are involved in cancer. The currently accepted hypothesis is that autophagy has dual and contradictory roles in carcinogenesis, but the precise mechanisms leading to autophagy in cancer are not yet fully defined and seem to be context dependent. Autophagy is a surveillance mechanism used by normal cells that protects them from the transformation to malignancy by removing damaged organelles and aggregated proteins and by reducing reactive oxygen species, mitochondrial abnormalities and DNA damage. However, autophagy also supports tumor formation by promoting access to nutrients that are critical to the metabolism and growth of tumor cells and by inhibiting cellular death and increasing drug resistance. Autophagy studies in CRC have focused on several molecules, mainly microtubule-associated protein 1 light chain 3, beclin 1, and autophagy related 5, with conflicting results. Beneficial effects were observed for some agents that modulate autophagy in CRC either alone or, more often, in combination with other agents. More extensive studies are needed in the future to clarify the roles of autophagy-related genes and modulators in colorectal carcinogenesis, and to develop potential beneficial agents for the prognosis and treatment of CRC.

Differential regulatory functions of three classes of phosphatidylinositol and phosphoinositide 3-kinases in autophagy

Autophagy is an evolutionarily conserved and exquisitely regulated self-eating cellular process with important biological functions. Phosphatidylinositol 3-kinases (PtdIns3Ks) and phosphoinositide 3-kinases (PI3Ks) are involved in the autophagic process. Here we aim to recapitulate how 3 classes of these lipid kinases differentially regulate autophagy. Generally, activation of the class I PI3K suppresses autophagy, via the well-established PI3K-AKT-MTOR (mechanistic target of rapamycin) complex 1 (MTORC1) pathway. In contrast, the class III PtdIns3K catalytic subunit PIK3C3/Vps34 forms a protein complex with BECN1 and PIK3R4 and produces phosphatidylinositol 3-phosphate (PtdIns3P), which is required for the initiation and progression of autophagy. The class II enzyme emerged only recently as an alternative source of PtdIns3P and autophagic initiator. However, the orthodox paradigm is challenged by findings that the PIK3CB catalytic subunit of class I PI3K acts as a positive regulator of autophagy, and PIK3C3 was thought to be an amino acid sensor for MTOR, which curbs autophagy. At present, a number of PtdIns3K and PI3K inhibitors, including specific PIK3C3 inhibitors, have been developed for suppression of autophagy and for clinical applications in autophagy-related human diseases.

Regulation of the Tumor-Suppressor Function of the Class III Phosphatidylinositol 3-Kinase Complex by Ubiquitin and SUMO

The occurrence of cancer is often associated with a dysfunction in one of the three central membrane-involution processes—autophagy, endocytosis or cytokinesis. Interestingly, all three pathways are controlled by the same central signaling module: the class III phosphatidylinositol 3-kinase (PI3K-III) complex and its catalytic product, the phosphorylated lipid phosphatidylinositol 3-phosphate (PtdIns3P). The activity of the catalytic subunit of the PI3K-III complex, the lipid-kinase VPS34, requires the presence of the membrane-targeting factor VPS15 as well as the adaptor protein Beclin 1. Furthermore, a growing list of regulatory proteins associates with VPS34 via Beclin 1. These accessory factors define distinct subunit compositions and thereby guide the PI3K-III complex to its different cellular and physiological roles. Here we discuss the regulation of the PI3K-III complex components by ubiquitination and SUMOylation. Especially Beclin 1 has emerged as a highly regulated protein, which can be modified with Lys11-, Lys48- or Lys63-linked polyubiquitin chains catalyzed by distinct E3 ligases from the RING-, HECT-, RBR- or Cullin-type. We also point out other cross-links of these ligases with autophagy in order to discuss how these data might be merged into a general concept.