Important role of autophagy in endothelial cell response to ionizing radiation

Nano-Sized Selenium Maintains Performance and Improves Health Status and Antioxidant Potential While Not Compromising Ultrastructure of Breast Muscle and Liver in Chickens

The poultry industry is looking for the most effective sources of selenium (Se) for commercial use. Over the past five years, nano-Se has attracted a great deal of attention in terms of its production, characterisation and possible application in poultry production. The objective of this study was to evaluate the effects of dietary levels of inorganic and organic Se, selenised yeast and nano forms of selenium on breast meat quality, liver and blood markers of antioxidants, the ultrastructure of tissue and the health status of chickens. A total of 300 one-day-old chicks Ross 308 were divided into 4 experimental groups, in 5 replications, with 15 birds per replication. Birds were fed the following treatments: a standard commercial diet containing inorganic Se in the form of inorganic Se at the level of 0.3 mg/kg diet and an experimental diet with an increased level of Se (0.5 mg/kg diet). The use of other forms of Se (nano-Se) versus sodium selenate significantly influences (p ≤ 0.05) a higher collagen content and does not impair physico-chemical properties in the breast muscle or the growth performance of the chickens. In addition, the use of other forms of selenium at an increased dose versus sodium selenate affected (p ≤ 0.01) the elongation of sarcomeres in the pectoral muscle while reducing (p ≤ 0.01) mitochondrial damage in hepatocytes and improving (p ≤ 0.05) oxidative indices. The use of nano-Se at a dose of 0.5 mg/kg feed has high bioavailability and low toxicity without negatively affecting the growth performance and while improving breast muscle quality parameters and the health status of the chickens.

Sex Differences in X-ray-Induced Endothelial Damage: Effect of Taurine and N-Acetylcysteine

Ionizing radiation (IR) can induce some associated pathological conditions due to numerous cell damages. The influence of sex is scarcely known, and even less known is whether the effect of antioxidants is sex-dependent. Given the increased use of IR, we investigated whether male human umbilical vein endothelial cells (MHUVECs) and female human umbilical vein endothelial cells (FHUVECs) respond differently to IR exposure and whether the antioxidants 10 mM taurine (TAU) and 5 mM N-acetylcysteine (NAC) can prevent IR-induced damage in a sex-dependent way. In untreated cells, sex differences were observed only during autophagy, which was higher in FHUVECs. In non-irradiated cells, preincubation with TAU and NAC did not modify viability, lactate dehydrogenase (LDH) release, migration, or autophagy, whereas only NAC increased malondialdehyde (MDA) levels in FHUVECs. X-ray irradiation increased LDH release and reduced viability and migration in a sex-independent manner. TAU and NAC did not affect viability while reduced LDH release in irradiated cells: they have the same protective effect in FHUVECs, while, TAU was more protective than NAC in male cells.. Moreover, TAU and NAC significantly promoted the closure of wounds in both sexes in irradiated cells, but NAC was more effective at doing this in FHUVECs. In irradiated cells, TAU did not change autophagy, while NAC attenuated the differences between the sexes. Finally, NAC significantly decreased MDA in MHUVECs and increased MDA in FHUVECs. In conclusion, FHUVECs appear to be more susceptible to IR damage, and the effects of the two antioxidants present some sex differences, suggesting the need to study the influence of sex in radiation mitigators.

Tissue Reactions and Mechanism in Cardiovascular Diseases Induced by Radiation

The long-term survival rate of cancer patients has been increasing as a result of advances in treatments and precise medical management. The evidence has accumulated that the incidence and mortality of non-cancer diseases have increased along with the increase in survival time and long-term survival rate of cancer patients after radiotherapy. The risk of cardiovascular disease as a radiation late effect of tissue damage reactions is becoming a critical challenge and attracts great concern. Epidemiological research and clinical trials have clearly shown the close association between the development of cardiovascular disease in long-term cancer survivors and radiation exposure. Experimental biological data also strongly supports the above statement. Cardiovascular diseases can occur decades post-irradiation, and from initiation and development to illness, there is a complicated process, including direct and indirect damage of endothelial cells by radiation, acute vasculitis with neutrophil invasion, endothelial dysfunction, altered permeability, tissue reactions, capillary-like network loss, and activation of coagulator mechanisms, fibrosis, and atherosclerosis. We summarize the most recent literature on the tissue reactions and mechanisms that contribute to the development of radiation-induced cardiovascular diseases (RICVD) and provide biological knowledge for building preventative strategies.

Atorvastatin Attenuates Radiotherapy-Induced Intestinal Damage through Activation of Autophagy and Antioxidant Effects

Abdominal or pelvic radiotherapy (RT) often results in small intestinal injury, such as apoptosis of epithelial cells and shortening of the villi. Atorvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, has many biological effects including cholesterol reduction, protection from cell damage, and autophagy activation. To reduce the extent of radiotherapy- (RT-) induced enteritis, we investigated the protective effects of atorvastatin against RT-induced damage of the intestinal tract. In this study, C57BL/6 mice were randomly distributed into the following groups (n = 8 per group): (1) control group: mice were fed water only, (2) atorvastatin group (Ator): mice were administered atorvastatin, (3) irradiation group (IR): mice received abdominal RT, (4) Ator+IR group: mice received abdominal RT following atorvastatin administration, and (5) Ator+IR+3-MA group: abdominal RT following atorvastatin and 3-methyladenine (an autophagy inhibitor) administration. Based on the assessment of modified Chiu's injury score and villus/crypt ratio, we found that atorvastatin administration significantly reduced intestinal mucosal damage induced by RT. Atorvastatin treatment reduced apoptosis (cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase), DNA damage (γH2AX and 53BP1), oxidative stress (OS, 4-hydroxynonenal), inflammatory molecules (phospho-NF-κB p65 and TGF-β), fibrosis (collagen I and collagen III), barrier leakage (claudin-2 and fluorescein isothiocyanate-dextran), disintegrity (fatty acid-binding protein 2), and dysfunction (lipopolysaccharide) caused by RT in small intestinal tissue. In addition, atorvastatin upregulated the expression of autophagy-active molecules (LC3B), antioxidants (heme oxygenase 1 and thioredoxin 1), and tight junction proteins (occludin and zonula occludens 1). However, the biological functions of atorvastatin in decreasing RT-induced enteritis were reversed after the administration of 3-MA; the function of antioxidant molecules and activity of thioredoxin reductase were independent of autophagy activation. Our results indicate that atorvastatin can effectively relieve RT-induced enteritis through autophagy activation and associated biological functions, including maintaining integrity and function and decreasing apoptosis, DNA damage, inflammation, OS, and fibrosis. It also acts via its antioxidative capabilities.

Rescue of lysosomal function as therapeutic strategy for SPG15 hereditary spastic paraplegia

SPG15 is a hereditary spastic paraplegia subtype caused by mutations in Spastizin, a protein encoded by the ZFYVE26 gene. Spastizin is involved in autophagosome maturation and autophagic lysosome reformation and SPG15-related mutations lead to autophagic lysosome reformation defects with lysosome enlargement, free lysosome depletion and autophagosome accumulation. Symptomatic and rehabilitative treatments are the only therapy currently available for patients. Here, we targeted autophagy and lysosomes in SPG15 patient-derived cells by using a library of autophagy-modulating compounds. We identified a rose of compounds affecting intracellular calcium levels, the calcium-calpain pathway or lysosomal functions, which reduced autophagosome accumulation. The six most effective compounds were tested in vivo in a new SPG15 loss of function Drosophila model that mimicked the reported SPG15 phenotype, with autophagosome accumulation, enlarged lysosomes, reduced free lysosomes, autophagic lysosome reformation defects and locomotor deficit. These compounds, namely verapamil, Bay K8644, 2',5'-dideoxyadenosine, trehalose, Small-Molecule Enhancer of Rapamycin 28 and trifluoperazine, improved lysosome biogenesis and function in vivo, demonstrating that lysosomes are a key pharmacological target to rescue SPG15 phenotype. Among the others, the Small-Molecule Enhancer of Rapamycin 28 was the most effective, rescuing both autophagic lysosome reformation defects and locomotor deficit, and could be considered as a potential therapeutic compound for this hereditary spastic paraplegia subtype.

Oxidative Stress Triggers Defective Autophagy in Endothelial Cells: Role in Atherothrombosis Development

Atherothrombosis, a multifactorial and multistep artery disorder, represents one of the main causes of morbidity and mortality worldwide. The development and progression of atherothrombosis is closely associated with age, gender and a complex relationship between unhealthy lifestyle habits and several genetic risk factors. The imbalance between oxidative stress and antioxidant defenses is the main biological event leading to the development of a pro-oxidant phenotype, triggering cellular and molecular mechanisms associated with the atherothrombotic process. The pathogenesis of atherosclerosis and its late thrombotic complications involve multiple cellular events such as inflammation, endothelial dysfunction, proliferation of vascular smooth muscle cells (SMCs), extracellular matrix (ECM) alterations, and platelet activation, contributing to chronic pathological remodeling of the vascular wall, atheromatous plague formation, vascular stenosis, and eventually, thrombus growth and propagation. Emerging studies suggest that clotting activation and endothelial cell (EC) dysfunction play key roles in the pathogenesis of atherothrombosis. Furthermore, a growing body of evidence indicates that defective autophagy is closely linked to the overproduction of reactive oxygen species (ROS) which, in turn, are involved in the development and progression of atherosclerotic disease. This topic represents a large field of study aimed at identifying new potential therapeutic targets. In this review, we focus on the major role played by the autophagic pathway induced by oxidative stress in the modulation of EC dysfunction as a background to understand its potential role in the development of atherothrombosis.

A Meta-Analysis of the Effects of High-LET Ionizing Radiations in Human Gene Expression

The use of high linear energy transfer (LET) ionizing radiation (IR) is progressively being incorporated in radiation therapy due to its precise dose localization and high relative biological effectiveness. At the same time, these benefits of particle radiation become a high risk for astronauts in the case of inevitable cosmic radiation exposure. Nonetheless, DNA Damage Response (DDR) activated via complex DNA damage in healthy tissue, occurring from such types of radiation, may be instrumental in the induction of various chronic and late effects. An approach to elucidating the possible underlying mechanisms is studying alterations in gene expression. To this end, we identified differentially expressed genes (DEGs) in high Z and high energy (HZE) particle-, γ-ray- and X-ray-exposed healthy human tissues, utilizing microarray data available in public repositories. Differential gene expression analysis (DGEA) was conducted using the R programming language. Consequently, four separate meta-analyses were conducted, after DEG lists were grouped depending on radiation type, radiation dose and time of collection post-irradiation. To highlight the biological background of each meta-analysis group, functional enrichment analysis and biological network construction were conducted. For HZE particle exposure at 8–24 h post-irradiation, the most interesting finding is the variety of DNA repair mechanisms that were downregulated, a fact that is probably correlated with complex DNA damage formation. Simultaneously, after X-ray exposure during the same hours after irradiation, DNA repair mechanisms continue to take place. Finally, in a further comparison of low- and high-LET radiation effects, the most prominent result is that autophagy mechanisms seem to persist and that adaptive immune induction seems to be present. Such bioinformatics approaches may aid in obtaining an overview of the cellular response to high-LET particles. Understanding these response mechanisms can consequently aid in the development of countermeasures for future space missions and ameliorate heavy ion treatments.

The role of Atg7-mediated autophagy in ionizing radiation-induced neural stem cell damage

Impairment of neurogenesis is thought to be one of the important mechanisms underlying radiation-induced cognitive decline. Self-renewal and differentiation of neural stem cells (NSCs) are important components of neurogenesis. It has been well established that autophagy plays an important role in neurodegenerative conditions, however, its role in radiation-induced cognitive decline remains unclear. Our previous studies have found that ionizing radiation (IR) induces autophagy in mouse neurons, and minocycline, an antibiotic that can cross the blood-brain barrier, protects neurons from radiation-induced apoptosis through promoting autophagy, thus may contribute to the improvement of mouse cognitive performance after whole-brain irradiation. In the present study, we investigated whether autophagy is involved in radiation-induced damage in self-renewal and differentiation of NSCs. We found that NSCs were extremely sensitive to IR. Irradiation induced autophagy in NSCs in a dose-dependent manner. Atg7 knockdown significantly decreased autophagy, thus increased the apoptosis levels in irradiated NSCs, suggesting that autophagy protected NSCs from radiation-induced apoptosis. Moreover, compared with the negative control NSCs, the neurosphere size was significantly reduced and the neuronal differentiation was notably inhibited in Atg7-deficient NSCs after irradiation, indicating that autophagy defect could exacerbate radiation-induced reduction in NSC self-renewal and differentiation potential. In conclusion, down-regulating autophagy by selective Atg7 knockdown in NSCs enhanced radiation-induced NSC damage, suggesting an important protective role of autophagy in maintaining neurogenesis. Along with the protective effect of autophagy on irradiated neurons, our results on NSCs not only shed the light on the involvement of autophagy in the development of radiation-induced cognitive decline, but also provided a potential target for preventing cognitive impairment after cranial radiation exposure.

Endothelial Autophagy: an Effective Target for Radiation-induced Cerebral Capillary Damage

Toxicity to central nervous system tissues is the common side effects for radiotherapy of brain tumor. The radiation toxicity has been thought to be related to the damage of cerebral endothelium. However, because of lacking a suitable high-resolution vivo model, cellular response of cerebral capillaries to radiation remained unclear. Here, we present the flk:eGFP transgenic zebrafish larvae as a feasible model to study the radiation toxicity to cerebral capillary. We showed that, in living zebrafish larvae, radiation could induce acute cerebral capillary shrinkage and blood-flow obstruction, resulting brain hypoxia and glycolysis retardant. Although in vivo neuron damage was also observed after the radiation exposure, further investigation found that they didn’t response to the same dosage of radiation in vitro, indicating that radiation induced neuron damage was a secondary-effect of cerebral vascular function damage. In addition, transgenic labeling and qPCR results showed that the radiation-induced acute cerebral endothelial damage was correlated with intensive endothelial autophagy. Different autophagy inhibitors could significantly alleviate the radiation-induced cerebral capillary damage and prolong the survival of zebrafish larvae. Therefore, we showed that radiation could directly damage cerebral capillary, resulting to blood flow deficiency and neuron death, which suggested endothelial autophagy as a potential target for radiation-induced brain toxicity.

SMER28 is a mTOR-independent small molecule enhancer of autophagy that protects mouse bone marrow and liver against radiotherapy

Effective cytoprotectors that are selective for normal tissues could decrease radiotherapy and chemotherapy sequelae and facilitate the safe administration of higher radiation doses. This could improve the cure rates of radiotherapy for cancer patients. Autophagy is a cytoplasmic cellular process that is necessary for the clearance of damaged or aged proteins and organelles. It is a strong determinant of post-irradiation cell fate. In this study, we investigated the effect of the mTOR-independent small molecule enhancer of autophagy (SMER28) on mouse liver autophagy and post-irradiation recovery of mouse bone marrow and liver. SMER28 enhanced the autophagy flux and improved the survival of normal hepatocytes. This effect was specific for normal cells because SMER28 had no protective effect on hepatoma or other cancer cell line survival in vitro. In vivo subcutaneous administration of SMER28 protected mouse liver and bone marrow against radiation damage and facilitated survival of mice after lethal whole body or abdominal irradiation. These findings open a new field of research on autophagy-targeting radioprotectors with clinical applications in oncology, occupational, and space medicine.

Changes in activity and structure of lysosomes from liver of mouse irradiated in vivo

PURPOSE

Lysosomes may have an important role in response to ionizing radiation. Moreover, radiation could affect autophagy, which process involves the activity of lysosomal enzymes. In the present study, the effect of ionizing radiation on the lysosomal compartment of mouse liver was investigated after in vivo exposure.

MATERIALS AND METHODS

Morphology and ultrastructure of hepatocytes were assessed by light and electron microscopy, and activities of selected lysosomal enzymes were assessed in 12, 36 and 120 h after exposure to the mean dose of 1 Gy. The levels of autophagy-related proteins LC3-II and p62 were compared by Western blotting between untreated and irradiated animals (120 h after exposure).

RESULTS

Increased number of autophagic vacuoles in hepatocytes from exposed animals was documented in the ultrastructural study; destroyed mitochondria were the dominant component of such vacuoles. Moreover, an increased activity of lysosomal hydrolases was observed after exposure. However, levels of autophagy substrates LC3-II and p62 were barely affected in exposed animals 120 h after irradiation when the accumulation of autophagic vacuoles was observed.

CONCLUSION

Effects of irradiation included an increased number of autophagic vacuoles, especially of autophagosomes, and increased activity of lysosomal enzymes. However, putative markers of autophagic flux were not observed, which suggested suppression of the completion of the radiation-mediated autophagy pathway.

Human Cytomegalovirus Replication Is Inhibited by the Autophagy-Inducing Compounds Trehalose and SMER28 through Distinctively Different Mechanisms

Human cytomegalovirus (HCMV) is the top viral cause of birth defects worldwide, and current therapies have high toxicity. We previously reported that the mTOR-independent autophagy-inducing disaccharide trehalose inhibits HCMV replication in multiple cell types. Here, we examine the mechanism of inhibition and introduce the autophagy inducer SMER28 as an additional inhibitor of HCMV acting through a different mechanism. We find that trehalose induces vacuolation and acidification of vacuoles and that debris, including debris with an appearance consistent with that of abnormal virions, is present in multivesicular bodies. Trehalose treatment increased the levels of Rab7, a protein required for lysosomal biogenesis and fusion, and slightly decreased the levels of Rab11, which is associated with recycling endosomes. We also present evidence that trehalose can promote autophagy without altering cellular glucose uptake. We show that SMER28 inhibits HCMV at the level of early protein production and interferes with viral genome replication in a cell type-dependent fashion. Finally, we show that SMER28 treatment does not cause the vacuolation, acidification, or redistribution of Rab7 associated with trehalose treatment and shows only a modest and cell type-dependent effect on autophagy. We propose a model in which the reciprocal effects on Rab7 and Rab11 induced by trehalose contribute to the redirection of enveloped virions from the plasma membrane to acidified compartments and subsequent degradation, and SMER28 treatment results in decreased expression levels of early and late proteins, reducing the number of virions produced without the widespread vacuolation characteristic of trehalose treatment.IMPORTANCE There is a need for less toxic HCMV antiviral drugs, and modulation of autophagy to control viral infection is a new strategy that takes advantage of virus dependence on autophagy inhibition. The present study extends our previous work on trehalose by showing a possible mechanism of action and introduces another autophagy-inducing compound, SMER28, that is effective against HCMV in several cell types. The mechanism by which trehalose induces autophagy is currently unknown, although our data show that trehalose does not inhibit cellular glucose uptake in cells relevant for HCMV replication but instead alters virion degradation by promoting acidic vacuolization. The comparison of our cell types and those used by others highlights the cell type-dependent nature of studying autophagy.

Ionizing radiation reduces ADAM10 expression in brain microvascular endothelial cells undergoing stress-induced senescence

Cellular senescence is associated with aging and is considered a potential contributor to age-associated neurodegenerative disease. Exposure to ionizing radiation increases the risk of developing premature neurovascular degeneration and dementia but also induces premature senescence. As cells of the cerebrovascular endothelium are particularly susceptible to radiation and play an important role in brain homeostasis, we investigated radiation-induced senescence in brain microvascular endothelial cells (EC). Using biotinylation to label surface proteins, streptavidin enrichment and proteomic analysis, we analyzed the surface proteome of stress-induced senescent EC in culture. An array of both recognized and novel senescence-associated proteins were identified. Most notably, we identified and validated the novel radiation-stimulated down-regulation of the protease, a disintegrin and metalloprotease 10 (ADAM10). ADAM10 is an important modulator of amyloid beta protein production, accumulation of which is central to the pathologies of Alzheimer's disease and cerebral amyloid angiopathy. Concurrently, we identified and validated increased surface expression of ADAM10 proteolytic targets with roles in neural proliferation and survival, inflammation and immune activation (L1CAM, NEO1, NEST, TLR2, DDX58). ADAM10 may be a key molecule linking radiation, senescence and endothelial dysfunction with increased risk of premature neurodegenerative diseases normally associated with aging.

Naked mole rats can undergo developmental, oncogene-induced and DNA damage-induced cellular senescence

Cellular senescence is an important anticancer mechanism that restricts proliferation of damaged or premalignant cells. Cellular senescence also plays an important role in tissue remodeling during development. However, there is a trade-off associated with cellular senescence as senescent cells contribute to aging pathologies. The naked mole rat (NMR) (Heterocephalus glaber) is the longest-lived rodent that is resistant to a variety of age-related diseases. Remarkably, NMRs do not show aging phenotypes until very late stages of their lives. Here, we tested whether NMR cells undergo cellular senescence. We report that the NMR displays developmentally programmed cellular senescence in multiple tissues, including nail bed, skin dermis, hair follicle, and nasopharyngeal cavity. NMR cells also underwent cellular senescence when transfected with oncogenic Ras. In addition, cellular senescence was detected in NMR embryonic and skin fibroblasts subjected to γ-irradiation (IR). However, NMR cells required a higher dose of IR for induction of cellular senescence, and NMR fibroblasts were resistant to IR-induced apoptosis. Gene expression analyses of senescence-related changes demonstrated that, similar to mice, NMR cells up-regulated senescence-associated secretory phenotype genes but displayed more profound down-regulation of DNA metabolism, transcription, and translation than mouse cells. We conclude that the NMR displays the same types of cellular senescence found in a short-lived rodent.

Non-thermal plasma induces a stress response in mesothelioma cells resulting in increased endocytosis, lysosome biogenesis and autophagy

Non-thermal plasma (NTP) is a potential new therapeutic modality for cancer. However, its mechanism of action remains unclear. Herein, we studied the effect of NTP on mesothelioma cells and fibroblasts to understand its anti-proliferative efficacy. Interestingly, NTP demonstrated greater selective anti-proliferative activity against mesothelioma cells relative to fibroblasts than cisplatin, which is used for mesothelioma treatment. The anti-proliferative effect of NTP was enhanced by pre-incubation with the cellular iron donor, ferric ammonium citrate (FAC), and inhibited by iron chelation using desferrioxamine (DFO). Three oxidative stress probes (CM-H2DCFDA, MitoSOX and C11-BODIPY) demonstrated reactive oxygen species (ROS) generation by NTP, which was inhibited by DFO. Moreover, NTP decreased transferrin receptor-1 and increased ferritin-H and -L chain expression that was correlated with decreased iron-regulatory protein expression and RNA-binding activity. This regulation was potentially due to increased intracellular iron in lysosomes, which was demonstrated via the Fe(II)-selective probe, HMRhoNox-M, and was consistent with autophagic-induction. Immunofluorescence using LysoTracker and Pepstatin A probes demonstrated increased cellular lysosome content, which was confirmed by elevated LAMP1 expression. The enhanced lysosomal biogenesis after NTP could be due to the observed increase in fluid-phase endocytosis and early endosome formation. These results suggest NTP acts as a stressor, which results in increased endocytosis, lysosome content and autophagy. In fact, NTP rapidly increased autophagosome formation, as judged by increased LC3B-II expression, which co-localized with LAMP1, indicating autophagolysosome formation. Autophagic-induction by NTP was confirmed using electron microscopy. In summary, NTP acts as a cellular stressor to rapidly induce fluid-phase endocytosis, lysosome biogenesis and autophagy.

Phosphatidylserine Translocation after Radiosurgery in an Animal Model of Arteriovenous Malformation

Phosphatidylserine (PS) is asymmetrically distributed across the plasma membrane, located predominantly on the inner leaflet in healthy cells. Translocation of PS to the outer leaflet makes it available as a target for biological therapies. We examined PS translocation after radiosurgery in an animal model of brain arteriovenous malformation (AVM). An arteriovenous fistula was created by end-to-side anastomosis of the left external jugular vein to the common carotid artery in 6-week-old, male Sprague Dawley rats. Six weeks after AVM creation, 15 rats underwent Gamma Knife stereotactic radiosurgery receiving a single 15 Gy dose to the margin of the fistula; 15 rats received sham treatment. Externalization of PS was examined by intravenous injection of a PS-specific near-infrared probe, PSVue-794, and in vivo fluorescence optical imaging at 1, 7, 21, 42, 63 and 84 days postirradiation. Fluorescent signaling indicative of PS translocation to the luminal cell surface accumulated in the AVM region, in both irradiated and nonirradiated animals, at all time points. Fluorescence was localized specifically to the AVM region and was not present in any other anatomical sites. Translocated PS increased over time in irradiated rats (P < 0.001) but not in sham-irradiated rats and this difference reached statistical significance at day 84 (P < 0.05). In summary, vessels within the mature rat AVM demonstrate elevated PS externalization compared to normal vessels. A single dose of ionizing radiation can increase PS externalization in a time-dependent manner. Strict localization of PS externalization within the AVM region suggests that stereotactic radiosurgery can serve as an effective priming agent and PS may be a suitable candidate for vascular-targeting approaches to AVM treatment.

Effects Of Oral Glutamine on Inflammatory and Autophagy Responses in Cancer Patients Treated With Abdominal Radiotherapy: A Pilot Randomized Trial

Background and Aims: Abdominal radiotherapy (RT) causes harm to the mid gastrointestinal mucosa by release of pro-inflammatory cytokines and promotes autophagic changes in tumor cells. This study was aimed to measure the effect of glutamine administration on markers of inflammation and autophagy in cancer patients treated with RT. Methods: In this double-blind, randomized, controlled pilot trial 43 patients under abdominal RT diagnosed of pelvic or abdominal malignancies receiving glutamine (30 g/d) or placebo (casein, 30 g/d). Patient recruitment took place in the Complejo Asistencial Universitario of León (CAULE), Spain. Patient evaluation took place at three different time points during the study: before RT (pre-treatment), in the middle of the RT period (mid-treatment), and after finishing RT (post-treatment). Data were compared by analysis of variance and the Newmann Keuls test. Significance was accepted at p < 0.05. Results Abdominal RT increased whole blood mRNA levels of inflammatory and autophagic markers, but glutamine administration showed significantly lower expression of toll-like receptor 4 (TLR4), CD36, interleukin-1β (IL-1β), tumor necrosis factor-alpha (TNF-α), cyclooxygenase-2 (COX-2), and matrix metalloproteinase-9 (MMP-9). Moreover, glutamine reduced the expression of the transcription factors nuclear factor kappa B (NF-κB) and activator protein 1 (AP-1). Glutamine also inhibited the autophagic response, with changes in expression of beclin-1, UV radiation resistance associated gene (UVRAG), autophagy-related protein-5 (Atg5), protein 1 light chain 3 (LC3), sequestosome 1 (p62/SQSTM1) and lysosome-associated membrane protein (LAMP)-1. Conclusions Findings provide evidence that glutamine decreases the inflammatory response and abolishes the changes of the autophagy machinery in patients receiving abdominal RT. The protective effect of glutamine must continue being investigated to disclose further molecular pathways.

Transcription Factor EB Expression in Early Breast Cancer Relates to Lysosomal/Autophagosomal Markers and Prognosis

BACKGROUND

Disrupting the autophagic balance to trigger autophagic death may open new strategies for cancer therapy. Transcription factor EB (TFEB) is a master regulator of lysosomal biogenesis and may play a role in cancer biology and clinical behavior.

METHODS

The expression of TFEB and the lysosomal cancer cell content (expression of lysosomal associated membrane protein 2a [LAMP2a] and cathepsin D) was studied in a series of 100 T1-stage breast carcinomas. Expression patterns were correlated with autophagy/hypoxia-related proteins, angiogenesis, and clinical outcome. The effect of hypoxic/acidic conditions on TFEB kinetics was studied in the MCF-7 cancer cell line.

RESULTS

Overexpression of TFEB in cancer cell cytoplasm and the perinuclear/nuclear area was noted in 23 (23%) of 100 cases. High LAMP2a and cathepsin D expression was noted in 30 (30%) of 100 and 28 (28%) of 100 cases, respectively. TFEB expression was directly linked with LAMP2a (P < .0001, r = 0.53), cathepsin D (P = .0002, r = 0.36), light chain 3A (LC3A) (P = .02, r = 0.22), and hypoxia-inducible factor 2-alpha (HIF-2α) (P = .01, r = 0.25) expression and inversely with progesterone receptor (P = .01, r = 0.22). High vascular density was directly linked with LAMP2a (P = .05, r = 0.18) and cathepsin D (P = .005, r = 0.28). In Kaplan-Meier survival analysis, TFEB and cathepsin D expression were related to an ominous prognosis (P = .001 and P = .03, respectively). In multivariate analysis, TFEB expression sustained its independent prognostic significance (P = .05, hazard ratio 2.1). In in vitro experiments, acidity triggered overexpression of TFEB and nuclear translocation.

CONCLUSION

Intense TFEB expression and lysosomal biogenesis, evident in one fourth of early breast carcinomas, define poor prognosis. Tumor acidity is among the microenvironmental conditions that trigger TFEB overactivity. TFEB is a sound target for the development of lysosomal targeting therapies.

Differences in Intracellular Fate of Two Spotted Fever Group Rickettsia in Macrophage-Like Cells

Spotted fever group (SFG) rickettsiae are recognized as important agents of human tick-borne diseases worldwide, such as Mediterranean spotted fever (Rickettsia conorii) and Rocky Mountain spotted fever (Rickettsia rickettsii). Recent studies in several animal models have provided evidence of non-endothelial parasitism by pathogenic SFG Rickettsia species, suggesting that the interaction of rickettsiae with cells other than the endothelium may play an important role in pathogenesis of rickettsial diseases. These studies raise the hypothesis that the role of macrophages in rickettsial pathogenesis may have been underappreciated. Herein, we evaluated the ability of two SFG rickettsial species, R. conorii (a recognized human pathogen) and Rickettsia montanensis (a non-virulent member of SFG) to proliferate in THP-1 macrophage-like cells, or within non-phagocytic cell lines. Our results demonstrate that R. conorii was able to survive and proliferate in both phagocytic and epithelial cells in vitro. In contrast, R. montanensis was able to grow in non-phagocytic cells, but was drastically compromised in the ability to proliferate within both undifferentiated and PMA-differentiated THP-1 cells. Interestingly, association assays revealed that R. montanensis was defective in binding to THP-1-derived macrophages; however, the invasion of the bacteria that are able to adhere did not appear to be affected. We have also demonstrated that R. montanensis which entered into THP-1-derived macrophages were rapidly destroyed and partially co-localized with LAMP-2 and cathepsin D, two markers of lysosomal compartments. In contrast, R. conorii was present as intact bacteria and free in the cytoplasm in both cell types. These findings suggest that a phenotypic difference between a non-pathogenic and a pathogenic SFG member lies in their respective ability to proliferate in macrophage-like cells, and may provide an explanation as to why certain SFG rickettsial species are not associated with disease in mammals.

Repression of the autophagic response sensitises lung cancer cells to radiation and chemotherapy

Background:

The cellular autophagic response to radiation is complex. Various cells and tissues respond differentially to radiation, depending on both the dose of exposure and the time post irradiation. In the current study, we determined the autophagosomal and lysosomal response to radiation in lung cancer cell lines by evaluating the expression of the associated proteins, as well as the effect of relevant gene silencing in radio and chemosensitisation. Furthermore, tumour sensitisation was evaluated in in vivo autophagic gene silencing model after irradiation.

Methods:

A549 and H1299 cell lines were utilised as in vitro cancer models. Both cell lines were transfected with various small-interfering RNAs, silencing auto-lysosomal genes, and irradiated with 4 Gy. Cell growth response was evaluated with AlamarBlue assay. Western blot and confocal microscopy were utilised for the characterisation of the auto-lysosomal flux. Also, the H1299 cell line was stable transfected with small-hairpin RNA of the MAP1LC3A gene, and the tumour radiosensitisation in Athymic Nude-Foxn1^nu was evaluated.

Results:

Following exposure to 4 Gy of radiation, A549 cells exhibited a significant induction of the autophagic flux, which was not supported by transcriptional activation of auto-lysosomal genes (LC3A, LC3B, p62, TFEB and LAMP2a), resulting in aggresome accumulation. Recovery of transcriptional activity and autophagy efficacy occurred 7 days post irradiation. Alternatively, H1299 cells, a relatively radio-resistant cell line, sharply responded with an early (at 2 days) transcriptional activation of auto-lysosomal genes that sustained an effective autophagosomal flux, resulting in adequate aggresome clearance. Subsequently, we tested the silencing of four genes (LC3A, LC3B, TFEB and LAMP2a), confirming a significant radiosensitisation and chemosensitisation to various chemotherapeutic agents, including cisplatin and taxanes. In mouse xenografts, exposure to radiation significantly reduced tumour growth (P<0.001), which was exacerbated among shLC3A-H1299 transfected tumours.

Conclusions:

The ability of lung cancer cells to survive after irradiation at 4 Gy depends on their ability to sustain a functional autophagic flux. Abrogation of such ability results in increased radiosensitivity and susceptibility to various chemotherapy agents. Selective inhibitors of cancer cell autophagic function may prove important for the eradication of lung cancer.

Different Roles of CHOP and JNK in Mediating Radiation-Induced Autophagy and Apoptosis in Breast Cancer Cells

Unfolded protein response (UPR) is comprised of complex and conserved stress pathways that function as a short-term adaptive mechanism to reduce levels of unfolded or misfolded proteins and maintain homeostasis in the endoplasmic reticulum (ER). UPR can be triggered by prolonged or persistent ER stress under many physiological or pathological conditions, including radiation exposure. Radiation-induced ER stress elicits autophagy and apoptosis in cancer cells, where C/EBP homologous protein (CHOP) and c-Jun NH2-terminal kinase (JNK) may play crucial roles. However, the specific mechanisms that regulate autophagy and apoptosis through CHOP and JNK after radiation exposure and how the balance of these activities determines the cellular radiosensitivity remain largely unclear. In this study, we found that exposure to X-ray radiation induced ER stress, UPR and high expression of CHOP and JNK. Furthermore, autophagy and apoptosis occurred in sequential order when breast cancer MDA-MB-231 and MCF-7 cells were exposed to X-ray radiation. CHOP gene knockdown with RNA interference inhibited autophagy and enhanced radiosensitivity in MDA-MB-231 cells, while impacting apoptosis and subsequently increasing radioresistance in MCF-7 cells. However, treatment with JNK inhibitor decreased autophagy while promoting apoptosis, thereby leading to radiosensitivity in both cell lines. Our results indicate that CHOP mediates radiation-induced autophagy and apoptosis in a cellular environment. Importantly, the functional consistency of regulating apoptosis and autophagy in these two irradiated breast cancer cell lines suggests that JNK may be more useful as a potential target for maximizing the efficacy of radiation therapy for breast cancers.

TIGAR overexpression diminishes radiosensitivity of parotid gland fibroblast cells and inhibits IR-induced cell autophagy

Our previous study proved that TP53-induced glycolysis and apoptosis regulator (TIGAR) abrogation is able to radiosensitize glioma cells. Whether TIGAR over-expression has radio-protective effect in human parotid gland cells is still unknown. In this study human parotid gland fibroblast Hs 917.T cells were transfected with pcDNA3.1-TIGAR, and clonogenic assay was performed to investigate the radiosensitivity of Hs 917.T cells over-expressing pcDNA3.1 or pcDNA3.1-TIGAR. Western blot was carried out to demonstrate the autophagy activity of cells being irradiated, and immunofluorescence assay was used to evaluate the DNA damage repair process of irradiated Hs 917.T cells. It was revealed that TIGAR over-expression could diminish the radiosensitivity of Hs 917.T cells, and the autophagy level induced by ionizing radiation (IR) was also decreased by TIGAR transfection. The mechanism might rely on TIGAR over-expression induced ROS scavenging and NADPH increasing. Using autophagy inhibitor, it was also elaborated that IR-induced autophagy in Hs 917.T cells was protective autophagy but not traumatic autophagy.

Intensified autophagy compromises the efficacy of radiotherapy against prostate cancer

INTRODUCTION

Radiotherapy is an equivalent alternative or complement to radical prostatectomy, with high therapeutic efficacy. High risk patients, however, experience high relapse rates, so that research on radio-sensitization is the most evident route to improve curability of this common disease.

MATERIALS AND METHODS

In the current study we investigated the autophagic activity in a series of patients with localized prostate tumors treated with radical radiotherapy, using the LC3A and the LAMP2a proteins as markers of autophagosome and lysosome cellular content, respectively. The role of autophagy on prostate cancer cell line resistance to radiation was also examined.

RESULTS

Using confocal microscopy on tissue biopsies, we showed that prostate cancer cells have, overall, high levels of LC3A and low levels of LAMP2a compared to normal prostate glands. Tumors with a 'highLC3A/lowLAMP2a' phenotype, suggestive of intensified lysosomal consumption, had a significantly poorer biochemical relapse free survival. The PC3 radioresistant cell line sustained remarkably its autophagic flux ability after radiation, while the DU145 radiosensitive one experiences a prolonged blockage of the autophagic process. This was assessed with aggresome accumulation detection and LC3A/LAMP2a double immunofluorescence, as well as with sequestrosome/p62 protein detection. By silencing the LC3A or LAMP2a expression, both cell lines became more sensitive to escalated doses of radiation.

CONCLUSIONS

High base line autophagy activity and cell ability to sustain functional autophagy define resistance of prostate cancer cells to radiotherapy. This can be reversed by blocking up-regulated components of the autophagy pathway, which may prove of importance in the field of clinical radiotherapy.

Autophagy modulates articular cartilage vesicle formation in primary articular chondrocytes

Chondrocyte-derived extracellular organelles known as articular cartilage vesicles (ACVs) participate in non-classical protein secretion, intercellular communication, and pathologic calcification. Factors affecting ACV formation and release remain poorly characterized; although in some cell types, the generation of extracellular vesicles is associated with up-regulation of autophagy. We sought to determine the role of autophagy in ACV production by primary articular chondrocytes. Using an innovative dynamic model with a light scatter nanoparticle counting apparatus, we determined the effects of autophagy modulators on ACV number and content in conditioned medium from normal adult porcine and human osteoarthritic chondrocytes. Healthy articular chondrocytes release ACVs into conditioned medium and show significant levels of ongoing autophagy. Rapamycin, which promotes autophagy, increased ACV numbers in a dose- and time-dependent manner associated with increased levels of autophagy markers and autophagosome formation. These effects were suppressed by pharmacologic autophagy inhibitors and short interfering RNA for ATG5. Caspase-3 inhibition and a Rho/ROCK inhibitor prevented rapamycin-induced increases in ACV number. Osteoarthritic chondrocytes, which are deficient in autophagy, did not increase ACV number in response to rapamycin. SMER28, which induces autophagy via an mTOR-independent mechanism, also increased ACV number. ACVs induced under all conditions had similar ecto-enzyme specific activities and types of RNA, and all ACVs contained LC3, an autophagosome-resident protein. These findings identify autophagy as a critical participant in ACV formation, and augment our understanding of ACVs in cartilage disease and repair.

The Multifunctions of WD40 Proteins in Genome Integrity and Cell Cycle Progression

Eukaryotic genome encodes numerous WD40 repeat proteins, which generally function as platforms of protein-protein interactions and are involved in numerous biological process, such as signal transduction, gene transcriptional regulation, protein modifications, cytoskeleton assembly, vesicular trafficking, DNA damage and repair, cell death and cell cycle progression. Among these diverse functions, genome integrity maintenance and cell cycle progression are extremely important as deregulation of them is clinically linked to uncontrolled proliferative diseases such as cancer. Thus, we mainly summarize and discuss the recent understanding of WD40 proteins and their molecular mechanisms linked to genome stability and cell cycle progression in this review, thereby demonstrating their pervasiveness and importance in cellular networks.