Reactive oxygen signaling and MAPK activation distinguish Epstein-Barr Virus (EBV)-positive versus EBV-negative Burkitt's lymphoma

Targeting EBV-encoded products: Implications for drug development in EBV-associated diseases

Epstein-Barr virus, a human gamma-herpesvirus, has a close connection to the pathogenesis of cancers and other diseases, which are a burden for public health worldwide. So far, several drugs or biomolecules have been discovered that can target EBV-encoded products for treatment, such as Silvestrol, affinity toxin, roscovitine, H20, H31, curcumin, thymoquinone, and ribosomal protein L22. These drugs activate or inhibit the function of some biomolecules, affecting subsequent signalling pathways by acting on the products of EBV. These drugs usually target LMP1, LMP2; EBNA1, EBNA2, EBNA3; EBER1, EBER2; Bam-HI A rightward transcript and BHRF1. Additionally, some promising findings in the fields of vaccines, immunological, and cellular therapies have been established. In this review, we mainly summarise the function of drugs mentioned above and unique mechanisms, hoping that we can help giving insight to the design of drugs for the treatment of EBV-associated diseases.

The master antioxidant defense is activated during EBV latent infection

IMPORTANCE

To our knowledge, this is the first report delineating the activation of the master antioxidant defense during EBV latency. We show that EBV-triggered reactive oxygen species production activates the Keap1-NRF2 pathway in EBV-transformed cells, and LMP1 plays a major role in this event, and the stress-related kinase TBK1 is required for NRF2 activation. Moreover, we show that the Keap1-NRF2 pathway is important for cell proliferation and EBV latency maintenance. Our findings disclose how EBV controls the balance between oxidative stress and antioxidant defense, which greatly improve our understanding of EBV latency and pathogenesis and may be leveraged to opportunities toward the improvement of therapeutic outcomes in EBV-associated diseases.

Overexpression of the mitochondrial anti-viral signaling protein, MAVS, in cancers is associated with cell survival and inflammation

Mitochondrial anti-viral signaling protein (MAVS) plays an important role in host defense against viral infection via coordinating the activation of NF-κB and interferon regulatory factors. The mitochondrial-bound form of MAVS is essential for its anti-viral innate immunity. Recently, tumor cells were proposed to mimic a viral infection by activating RNA-sensing pattern recognition receptors. Here, we demonstrate that MAVS is overexpressed in a panel of viral non-infected cancer cell lines and patient-derived tumors, including lung, liver, bladder, and cervical cancers, and we studied its role in cancer. Silencing MAVS expression reduced cell proliferation and the expression and nuclear translocation of proteins associated with transcriptional regulation, inflammation, and immunity. MAVS depletion reduced expression of the inflammasome components and inhibited its activation/assembly. Moreover, MAVS directly interacts with the mitochondrial protein VDAC1, decreasing its conductance, and we identified the VDAC1 binding site in MAVS. Our findings suggest that MAVS depletion, by reducing cancer cell proliferation and inflammation, represents a new target for cancer therapy.

Mitochondria-Targeted Antioxidants as a Therapeutic Strategy for Chronic Obstructive Pulmonary Disease

Oxidative stress is a major hallmark of COPD, contributing to inflammatory signaling, corticosteroid resistance, DNA damage, and accelerated lung aging and cellular senescence. Evidence suggests that oxidative damage is not solely due to exogenous exposure to inhaled irritants, but also endogenous sources of oxidants in the form of reactive oxygen species (ROS). Mitochondria, the major producers of ROS, exhibit impaired structure and function in COPD, resulting in reduced oxidative capacity and excessive ROS production. Antioxidants have been shown to protect against ROS-induced oxidative damage in COPD, by reducing ROS levels, reducing inflammation, and protecting against the development of emphysema. However, currently available antioxidants are not routinely used in the management of COPD, suggesting the need for more effective antioxidant agents. In recent years, a number of mitochondria-targeted antioxidant (MTA) compounds have been developed that are capable of crossing the mitochondria lipid bilayer, offering a more targeted approach to reducing ROS at its source. In particular, MTAs have been shown to illicit greater protective effects compared to non-targeted, cellular antioxidants by further reducing apoptosis and offering greater protection against mtDNA damage, suggesting they are promising therapeutic agents for the treatment of COPD. Here, we review evidence for the therapeutic potential of MTAs as a treatment for chronic lung disease and discuss current challenges and future directions.

Cardioprotective potential of vanillic acid

Nowadays, cardiovascular diseases (CVDs) are a global threat to public health, accounting for almost one-third of all deaths worldwide. One of the key mechanistic pathways contributing to the development of CVDs, including cardiotoxicity (CTX) and myocardial ischaemia-reperfusion injury (MIRI) is oxidative stress (OS). Increased generation of reactive oxygen species (ROS) is closely associated with decreased antioxidant capacity and mitochondrial dysfunction. Currently, despite the availability of modern pharmaceuticals, dietary-derived antioxidants are becoming more popular in developed societies to delay the progression of CVDs. One of the antioxidants derived from herbs, fruits, whole grains, juices, beers, and wines is vanillic acid (VA), which, as a phenolic compound, possesses different therapeutic properties, including cardioprotective. Based on experimental evidence, VA improves mitochondrial function as a result of the reduction in ROS production, aggravates antioxidative status, scavenges free radicals, and reduces levels of lipid peroxidation, thereby decreasing cardiac dysfunction, in particular CTX and MIRI. Considering the role of OS in the pathophysiology of CVDs, the purpose of this study is to comprehensively address recent evidence on the antioxidant importance of VA in the cardiovascular system.

Oral Microbiota Alteration and Roles in Epstein-Barr Virus Reactivation in Nasopharyngeal Carcinoma

Microbiota has recently emerged as a critical factor associated with multiple malignancies. Nasopharyngeal carcinoma (NPC) is highly associated with Epstein-Barr virus (EBV); the oncovirus resides and is transmitted in the oral cavity. However, the alternation of oral microbiota in NPC patients and its potential link to EBV reactivation and host cell response under the simultaneous existence of EBV and specific bacteria is largely unknown. Here, oral microbiota profiles of 303 NPC patients and controls with detailed clinical information, including serum EBV anti-virus capsid antigen (VCA) IgA level, were conducted. A distinct microbial community with lower diversity and imbalanced composition in NPC patients was observed. Notably, among enriched bacteria in patients, Streptococcus sanguinis was associated with anti-VCA IgA, an indicator of NPC risk and EBV reactivation. By measuring the concentration of its metabolite, hydrogen peroxide (H2O2), in the saliva of clinical patients, we found the detection rate of H2O2 was 2-fold increased compared to healthy controls. Further coculture assay of EBV-positive Akata cells with bacteria in vitro showed that S. sanguinis induced EBV lytic activation by its metabolite, H2O2. Host and EBV whole genome-wide transcriptome sequencing and EBV methylation assays showed that H2O2 triggered the host cell signaling pathways, notably tumor necrosis factor alpha (TNF-α) via NF-κB, and induced the demethylation of the global EBV genome and the expression of EBV lytic-associated genes, which could result in an increase of virus particle release and potential favorable events toward tumorigenesis. In brief, our study identified a characterized oral microbial profile in NPC patients and established a robust link between specific oral microbial alteration and switch of latency to lytic EBV infection status in the oral cavity, which provides novel insights into EBV's productive cycle and might help to further clarify the etiology of NPC. IMPORTANCE EBV is classified as the group I human carcinogen and is associated with multiple cancers, including NPC. The interplays between the microbiota and oncovirus in cancer development remain largely unknown. In this study, we investigate the interactions between resident microbes and EBV coexistence in the oral cavity of NPC patients. We identify a distinct oral microbial feature for NPC patients. Among NPC-enriched bacteria, we illustrated that a specific species, S. sanguinis, associated with elevated anti-IgA VCA in patients, induced EBV lytic activation by its by-product, H2O2, and activated the TNF-α/NF-κB pathway of EBV-positive B cells in vitro, together with increased detection rate of H2O2 in patients' oral cavities, which strengthened the evidence of bacteria-virus-host interaction in physiological circumstances. The effects of imbalanced microbiota on the EBV latent-to-lytic switch in the oral cavity might create the likelihood of EBV infection in epithelial cells at the nasopharynx and help malignant transition and cancer development.

Mitochondria-Targeted Antioxidants, an Innovative Class of Antioxidant Compounds for Neurodegenerative Diseases: Perspectives and Limitations

Neurodegenerative diseases comprise a wide spectrum of pathologies characterized by progressive loss of neuronal functions and structures. Despite having different genetic backgrounds and etiology, in recent years, many studies have highlighted a point of convergence in the mechanisms leading to neurodegeneration: mitochondrial dysfunction and oxidative stress have been observed in different pathologies, and their detrimental effects on neurons contribute to the exacerbation of the pathological phenotype at various degrees. In this context, increasing relevance has been acquired by antioxidant therapies, with the purpose of restoring mitochondrial functions in order to revert the neuronal damage. However, conventional antioxidants were not able to specifically accumulate in diseased mitochondria, often eliciting harmful effects on the whole body. In the last decades, novel, precise, mitochondria-targeted antioxidant (MTA) compounds have been developed and studied, both in vitro and in vivo, to address the need to counter the oxidative stress in mitochondria and restore the energy supply and membrane potentials in neurons. In this review, we focus on the activity and therapeutic perspectives of MitoQ, SkQ1, MitoVitE and MitoTEMPO, the most studied compounds belonging to the class of MTA conjugated to lipophilic cations, in order to reach the mitochondrial compartment.

Mitochondrial protein, TBRG4, modulates KSHV and EBV reactivation from latency

Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr (EBV) are gammaherpesviruses associated with multiple human malignancies. KSHV is the etiological agent of Kaposi's Sarcoma, primary effusion lymphoma (PEL) and multicentric Castleman's disease (MCD). EBV is associated with Burkitt's lymphoma (BL), Hodgkin's lymphoma (HL), nasopharyngeal carcinoma (NPC) and gastric carcinoma (GC). KSHV and EBV establish life-long latency in the human host with intermittent periods of lytic reactivation. Here, we identified a cellular factor named transforming growth factor-beta regulator 4 (TBRG4) that plays a role in the gammaherpesvirus lifecycle. We find that TBRG4, a protein that is localized to the mitochondria, can regulate lytic reactivation from latency of both KSHV and EBV. Knockdown of TBRG4 in cells latently infected with KSHV or EBV induced viral lytic gene transcription and replication. TBRG4 deficiency causes mitochondrial stress and increases reactive oxygen species (ROS) production. Treatment with a ROS scavenger decreased viral reactivation from latency in TBRG4-depleted cells. These data suggest that TBRG4 serves as a cellular repressor of KSHV and EBV reactivation through the regulation of ROS production.

Unboxing the molecular modalities of mutagens in cancer

The etiology of the majority of human cancers is associated with a myriad of environmental causes, including physical, chemical, and biological factors. DNA damage induced by such mutagens is the initial step in the process of carcinogenesis resulting in the accumulation of mutations. Mutational events are considered the major triggers for introducing genetic and epigenetic insults such as DNA crosslinks, single- and double-strand DNA breaks, formation of DNA adducts, mismatched bases, modification in histones, DNA methylation, and microRNA alterations. However, DNA repair mechanisms are devoted to protect the DNA to ensure genetic stability, any aberrations in these calibrated mechanisms provoke cancer occurrence. Comprehensive knowledge of the type of mutagens and carcinogens and the influence of these agents in DNA damage and cancer induction is crucial to develop rational anticancer strategies. This review delineated the molecular mechanism of DNA damage and the repair pathways to provide a deep understanding of the molecular basis of mutagenicity and carcinogenicity. A relationship between DNA adduct formation and cancer incidence has also been summarized. The mechanistic basis of inflammatory response and oxidative damage triggered by mutagens in tumorigenesis has also been highlighted. We elucidated the interesting interplay between DNA damage response and immune system mechanisms. We addressed the current understanding of DNA repair targeted therapies and DNA damaging chemotherapeutic agents for cancer treatment and discussed how antiviral agents, anti-inflammatory drugs, and immunotherapeutic agents combined with traditional approaches lay the foundations for future cancer therapies.

Reorienting of pramipexole as a promising therapy for acute pancreatitis in a rat model by suppressing TLR-4\NF-κB p65\NLRP3 inflammasome signaling

OBJECTIVE

Acute pancreatitis (AP), a disorder of global importance, has a growing incidence and prevalence, particularly in the western world. Its complications include pseudo-cysts and chronic pancreatitis. Pramipexole (PMX), a D2/3 receptor selecting agonist used in Parkinsonism, has reported anti-inflammatory effects lately.

PURPOSE

Exploring the potential curative role of PMX in an l-arginine-induced acute pancreatitis rat model besides a possible mechanistic pathway.

METHODS

Rats were divided randomly into three groups: control, l-arginine, and "l-arginine + PMX". 7 days after AP induction, rats decapitated and estimated for serum amylase, lipase, glucose, pancreatic inflammatory mediators "toll-like receptor-4, nuclear factor- kappa B p65 ,serum tumor necrosis factor-α, NLRP3 inflammasome, caspase-1, interleukin-1 beta, oxidative biomarkers "malondialdehyde, myeloperoxidase, nitrite/nitrate, reduced glutathione, and the apoptotic marker "caspase-3", with pancreatic histopathological changes.

RESULTS

L-arginine mediated AP proved by elevated serum lipase and amylase, pancreatic inflammatory, oxidative and apoptotic markers with infiltration of inflammatory cells using hematoxylin and eosin stain. PMX improved all these adverse signs of AP greatly.

CONCLUSION

PMX might be considered as an innovative therapy for AP due to its remarkable antioxidant, anti-apoptotic, and anti-inflammatory effects, which are attributed to the suppression of the NLRP3 inflammasome and its downstream inflammatory cytokines.

Epstein–Barr Virus Infection in Lung Cancer: Insights and Perspectives

Lung cancer (LC) is the leading cause of cancer death worldwide. Tobacco smoke is the most frequent risk factor etiologically associated with LC, although exposures to other environmental factors such as arsenic, radon or asbestos are also involved. Additionally, the involvement of some viral infections such as high-risk human papillomaviruses (HR-HPVs), Merkel cell polyomavirus (MCPyV), Jaagsiekte Sheep Retrovirus (JSRV), John Cunningham Virus (JCV), and Epstein–Barr virus (EBV) has been suggested in LC, though an etiological relationship has not yet been established. EBV is a ubiquitous gamma herpesvirus causing persistent infections and some lymphoid and epithelial tumors. Since EBV is heterogeneously detected in LCs from different parts of the world, in this review we address the epidemiological and experimental evidence of a potential role of EBV. Considering this evidence, we propose mechanisms potentially involved in EBV-associated lung carcinogenesis. Additional studies are warranted to dissect the role of EBV in this very frequent malignancy.

The Ethyl Acetate Subfraction of Polygonum cuspidatum Root Containing Emodin Affect EBV Gene Expression and Induce EBV-Positive Cells Apoptosis

Epstein-Barr virus (EBV), a human herpesvirus, is several human lymphoid malignancies-associated. Our earlier study found the effect of Polygonum cuspidatum root on promoting EBV-positive apoptosis. Therefore, this study investigated the effects of the Polygonum cuspidatum ethyl acetate subfraction containing emodin on EBV gene expression and anti-EBV tumor cells. Resultantly, the the Polygonum cuspidatum ethyl acetate subfraction containing emodin (F3a) promoted Raji cell death (50% cytotoxic concentration, CC₅₀: 12.08 µg/mL); the 12.5 µg/mL F3a effect transcribed BRLF1 and BNLF1 and increased latent membrane protein 1 (LMP1), which may reduce the intracellular phospho-extracellular signal-regulated kinase (ERK) and phospho-inhibitor of Nuclear factor kappa B α (IκBα). Meanwhile, the Raji cells increased the intracellular reactive-oxygen species (ROS), activated the apoptosis-related proteins, cleaved caspase 3 and poly(ADP-ribose)polymerase (PARP), and increased the apoptosis percentage. Therefore, the Polygonum cuspidatum ethyl acetate subfraction containing emodin could be a therapeutic drug for EBV-related tumors.

New Look of EBV LMP1 Signaling Landscape

Simple Summary

Epstein-Barr Virus (EBV) infection is associated with various lymphomas and carcinomas as well as other diseases in humans. The transmembrane protein LMP1 plays versatile roles in EBV life cycle and pathogenesis, by perturbing, reprograming, and regulating a large range of host cellular mechanisms and functions, which have been increasingly disclosed but not fully understood so far. We summarize recent research progress on LMP1 signaling, including the novel components LIMD1, p62, and LUBAC in LMP1 signalosome and LMP1 novel functions, such as its induction of p62-mediated selective autophagy, regulation of metabolism, induction of extracellular vehicles, and activation of NRF2-mediated antioxidative defense. A comprehensive understanding of LMP1 signal transduction and functions may allow us to leverage these LMP1-regulated cellular mechanisms for clinical purposes.

Abstract

The Epstein–Barr Virus (EBV) principal oncoprotein Latent Membrane Protein 1 (LMP1) is a member of the Tumor Necrosis Factor Receptor (TNFR) superfamily with constitutive activity. LMP1 shares many features with Pathogen Recognition Receptors (PRRs), including the use of TRAFs, adaptors, and kinase cascades, for signal transduction leading to the activation of NFκB, AP1, and Akt, as well as a subset of IRFs and likely the master antioxidative transcription factor NRF2, which we have gradually added to the list. In recent years, we have discovered the Linear UBiquitin Assembly Complex (LUBAC), the adaptor protein LIMD1, and the ubiquitin sensor and signaling hub p62, as novel components of LMP1 signalosome. Functionally, LMP1 is a pleiotropic factor that reprograms, balances, and perturbs a large spectrum of cellular mechanisms, including the ubiquitin machinery, metabolism, epigenetics, DNA damage response, extracellular vehicles, immune defenses, and telomere elongation, to promote oncogenic transformation, cell proliferation and survival, anchorage-independent cell growth, angiogenesis, and metastasis and invasion, as well as the development of the tumor microenvironment. We have recently shown that LMP1 induces p62-mediated selective autophagy in EBV latency, at least by contributing to the induction of p62 expression, and Reactive Oxygen Species (ROS) production. We have also been collecting evidence supporting the hypothesis that LMP1 activates the Keap1-NRF2 pathway, which serves as the key antioxidative defense mechanism. Last but not least, our preliminary data shows that LMP1 is associated with the deregulation of cGAS-STING DNA sensing pathway in EBV latency. A comprehensive understanding of the LMP1 signaling landscape is essential for identifying potential targets for the development of novel strategies towards targeted therapeutic applications.

Lipid Rafts Interaction of the ARID3A Transcription Factor with EZRIN and G-Actin Regulates B-Cell Receptor Signaling

Several diseases originate via dysregulation of the actin cytoskeleton. The ARID3A/Bright transcription factor has also been implicated in malignancies, primarily those derived from hematopoietic lineages. Previously, we demonstrated that ARID3A shuttles between the nucleus and the plasma membrane, where it localizes within lipid rafts. There it interacts with components of the B-cell receptor (BCR) to reduce its ability to transmit downstream signaling. We demonstrate here that a direct component of ARID3A-regulated BCR signal strength is cortical actin. ARID3A interacts with actin exclusively within lipid rafts via the actin-binding protein EZRIN, which confines unstimulated BCRs within lipid rafts. BCR ligation discharges the ARID3A-EZRIN complex from lipid rafts, allowing the BCR to initiate downstream signaling events. The ARID3A-EZRIN interaction occurs almost exclusively within unpolymerized G-actin, where EZRIN interacts with the multifunctional ARID3A REKLES domain. These observations provide a mechanism by which a transcription factor directly regulates BCR signaling via linkage to the actin cytoskeleton with consequences for B-cell-related neoplasia.

Signaling pathways of EBV-induced oncogenesis

Epstein-Barr virus (EBV) is closely associated with multiple human cancers. EBV-associated cancers are mainly lymphomas derived from B cells and T cells (Hodgkin lymphoma, Burkitt lymphoma, NK/T-cell lymphoma, and posttransplant lymphoproliferative disorder (PTLD)) and carcinomas derived from epithelial cells (nasopharyngeal carcinoma and gastric carcinoma). EBV can induce oncogenesis in its host cell by activating various signaling pathways, such as nuclear factor-κB (NF-κB), phosphoinositide-3-kinase/protein kinase B (PI3K/AKT), Janus kinase/signal transducer and transcription activator (JAK/STAT), mitogen-activated protein kinase (MAPK), transforming growth factor-β (TGF-β), and Wnt/β-catenin, which are regulated by EBV-encoded proteins and noncoding RNA. In this review, we focus on the oncogenic roles of EBV that are mediated through the aforementioned signaling pathways.

Targeting the signaling in Epstein-Barr virus-associated diseases: mechanism, regulation, and clinical study

Epstein–Barr virus-associated diseases are important global health concerns. As a group I carcinogen, EBV accounts for 1.5% of human malignances, including both epithelial- and lymphatic-originated tumors. Moreover, EBV plays an etiological and pathogenic role in a number of non-neoplastic diseases, and is even involved in multiple autoimmune diseases (SADs). In this review, we summarize and discuss some recent exciting discoveries in EBV research area, which including DNA methylation alterations, metabolic reprogramming, the changes of mitochondria and ubiquitin-proteasome system (UPS), oxidative stress and EBV lytic reactivation, variations in non-coding RNA (ncRNA), radiochemotherapy and immunotherapy. Understanding and learning from this advancement will further confirm the far-reaching and future value of therapeutic strategies in EBV-associated diseases.

Nicotinamide adenine dinucleotide phosphate oxidase inhibitor induces apoptosis on Epstein-Barr virus positive B lymphoma cells

Over-expression of nicotinamide adenine dinucleotide phosphate oxidase (Nox) isoform enzymes was recently reported in various cancers including Burkitt’s lymphoma (BL). However, the functions of Nox isoform enzymes in BL remain poorly understood. In this study, Nox isoform expression and the effects of a Nox-specific inhibitor were evaluated in Epstein-Barr virus (EBV)-positive Raji BL cells in comparison with EBV-negative Ramos BL cells. To evaluate Nox enzyme expression in Raji and Ramos BL cells, polymerase chain reaction (PCR) and western blot analysis were performed. To verify the intracellular signaling mechanism of the Nox inhibitor-induced apoptosis of Raji cells, WST-1 assay, trypan blue exclusion method, flow cytometry, PCR, western blotting, and bromodeoxyuridine staining were conducted. Experiments using the pan-caspase inhibitor z-VAD, reactive oxygen species scavenger N-acetyl-L-cysteine (NAC), and Bim inhibitor 1 were performed. PCR and western blot results showed that Nox isoform enzymes were highly expressed in EBV-positive BL Raji cells compared with EBV-negative BL Ramos cells. The Nox2 inhibitor induced apoptosis of Raji cells in time- and dose-dependent manners. The Nox2 inhibitor also caused up-regulation of Bim and Noxa, down-regulation of Mcl-1, translocation of Bax, release of cytochrome c, and caspase cascade activation, resulting in apoptosis. Furthermore, z-VAD, NAC, and BI-1 effectively blocked the Nox2 inhibitor-induced apoptosis of Raji cells. Taken together, these results provide a novel insight into the mechanism of Nox inhibitor-induced apoptosis and evidence for Nox as a therapeutic target to treat EBV-positive malignancies.

Mitochondria-Targeted Antioxidants: A Step towards Disease Treatment

Mitochondria are the main organelles that produce adenosine 5′-triphosphate (ATP) and reactive oxygen species (ROS) in eukaryotic cells and meanwhile susceptible to oxidative damage. The irreversible oxidative damage in mitochondria has been implicated in various human diseases. Increasing evidence indicates the therapeutic potential of mitochondria-targeted antioxidants (MTAs) for oxidative damage-associated diseases. In this article, we introduce the advantageous properties of MTAs compared with the conventional (nontargeted) ones, review different mitochondria-targeted delivery systems and antioxidants, and summarize their experimental results for various disease treatments in different animal models and clinical trials. The combined evidence demonstrates that mitochondrial redox homeostasis is a potential target for disease treatment. Meanwhile, the limitations and prospects for exploiting MTAs are discussed, which might pave ways for further trial design and drug development.

Targeted Therapies for Epstein-Barr Virus-Associated Lymphomas

Simple Summary

Epstein-Barr virus (EBV) is the first-discovered and important human tumor virus. It infects more than 90% of human population and induces various lymphomas. Development of specific targeted therapies is very critical for treatment of EBV-induced lymphomas, but it remains a great challenge. In this review, we introduced the current progress of EBV-specific therapies and the promising approaches that can be developed as novel targeted therapies, which involve protective or therapeutic strategies to target these lymphomas on different levels. This work will provide new insights into the development of new targeted therapies against EBV-associated lymphomas.

Abstract

The Epstein-Barr virus (EBV) is the first human tumor virus identified that can transform quiescent B lymphocytes into lymphoblastoid cell lines (LCLs) in vitro. EBV can establish asymptomatic life-long persistence and is associated with multiple human malignancies, including non-Hodgkin lymphoma and Hodgkin lymphoma, as well as infectious mononucleosis. Although EBV-associated lymphomagenesis has been investigated for over 50 years, viral-mediated transformation is not completely understood, and the development of EBV-specific therapeutic strategies to treat the associated cancers is still a major challenge. However, the rapid development of several novel therapies offers exciting possibilities to target EBV-induced lymphomas. This review highlights targeted therapies with potential for treating EBV-associated lymphomas, including small molecule inhibitors, immunotherapy, cell therapy, preventative and therapeutic vaccines, and other potent approaches, which are novel strategies for controlling, preventing, and treating these viral-induced malignances.

The Multifunctional Protein p62 and Its Mechanistic Roles in Cancers

The multifunctional signaling hub p62 is well recognized as a ubiquitin sensor and a selective autophagy receptor. As a ubiquitin sensor, p62 promotes NFκB activation by facilitating TRAF6 ubiquitination and aggregation. As a selective autophagy receptor, p62 sorts ubiquitinated substrates including p62 itself for lysosome-mediated degradation. p62 plays crucial roles in myriad cellular processes including DNA damage response, aging/senescence, infection and immunity, chronic inflammation, and cancerogenesis, dependent on or independent of autophagy. Targeting p62-mediated autophagy may represent a promising strategy for clinical interventions of different cancers. In this review, we summarize the transcriptional and post-translational regulation of p62, and its mechanistic roles in cancers, with the emphasis on its roles in regulation of DNA damage response and its connection to the cGAS-STING-mediated antitumor immune response, which is promising for cancer vaccine design.

Mean platelet counts are relatively decreased with malaria but relatively increased with endemic Burkitt Lymphoma in Uganda, Tanzania, and Kenya

Platelet counts are decreased in Plasmodium falciparum malaria, which is aetiologically linked with endemic Burkitt lymphoma (eBL). However, the pattern of platelet counts in eBL cases is unknown. We studied platelet counts in 582 eBL cases and 2 248 controls enrolled in a case-control study in Uganda, Tanzania and Kenya (2010-2016). Mean platelet counts in controls or eBL cases with or without malaria-infection in controls versus eBLcases were compared using Student's t-test. Odds ratios (ORs) and two-sided 95% confidence intervals (95% CIs) were estimated using multiple logistic regression, controlling for age, sex, haemoglobin and white blood cell counts. Platelets were decreased with malaria infection in the controls [263 vs. 339 × 10⁹ platelets/l, P < 0·0001; adjusted OR (aOR) = 3·42, 95% CI: 2·79-4·18] and eBL cases (314 vs. 367 × 10⁹ platelets/l, P-value = 0·002; aOR = 2·36, 95% CI: 1·49-3·73). Unexpectedly, platelets were elevated in eBL cases versus  controls in overall analyses (mean: 353 vs. 307 × 10⁹ platelets/l, P < 0·0001; aOR = 1·41; 95% CI: 1·12-1·77), and when restricted to malaria-positive (mean 314 vs. 263 × 10⁹ platelets/l, P < 0·0001; OR = 2·26; 95% CI: 1·56-3·27) or malaria-negative (mean 367 vs. 339 × 10⁹ platelets/l, P < 0·001; OR = 1·46; 95% CI: 1·17-1·83) subjects. Platelets were decreased with malaria infection in controls and eBL cases but elevated with eBL.

Genomic and Transcriptomic Characterization of Natural Killer T Cell Lymphoma

Natural killer/T cell lymphoma (NKTCL) is an aggressive and heterogeneous entity of non-Hodgkin lymphoma, strongly associated with Epstein-Barr virus (EBV) infection. To identify molecular subtypes of NKTCL based on genomic structural alterations and EBV sequences, we performed multi-omics study on 128 biopsy samples of newly diagnosed NKTCL and defined three prominent subtypes, which differ significantly in cell of origin, EBV gene expression, transcriptional signatures, and responses to asparaginase-based regimens and targeted therapy. Our findings thus identify molecular networks of EBV-associated pathogenesis and suggest potential clinical strategies on NKTCL.

APX-115A, a pan-NADPH Oxidase Inhibitor, Induces Caspase-dependent Cell Death by Suppressing NOX4-ROS Signaling in EBV-infected Retinal Epithelial Cells

PURPOSE

Epstein-Barr virus is a γ-herpes virus that infects primary B cells and can transform infected cells into immortalized lymphoblastoid cell lines (LCL). The role of EBV in malignancies such as Burkitt's lymphoma and nasopharyngeal carcinoma is well understood, however, its role in EBV-infected retinal cells remains poorly understood. Therefore, we investigated the effect of EBV on the growth of retinal cells.

METHODS

Previously, we established and reported a cell line model to address the relationship between EBV infection and retinal cell proliferation that used adult retinal pigment epithelium (ARPE-19) and EBV infection. To determine the effect of EBV on ARPE-19 cells, cell death was measured by propidium iodine/annexin V staining and reactive oxygen species (ROS) were measured by FACS, and protein expression was evaluated using western blot analysis. Also, downregulation of LMP1 and NADPH oxidase 4 (NOX4) expression was accomplished using siRNA technology.

RESULTS

We found that ROS were dramatically increased in EBV-infected ARPE19 cells (APRE19/EBV) relative to the parental cell line. Additionally, the expression level of NOX4, a main source of ROS, was upregulated by EBV infection. Interestingly, downregulation of LMP1, one of the EBV viral onco-proteins, completely decreased EBV-induced ROS accumulation and the upregulation of NOX4. Treatment with APX-115A, a pan-NOX inhibitor, induced apoptotic cell death of only the EBV-infected ARPE19 cells but not the parental cell line. Pretreatment with z-VAD, a pan-caspase inhibitor, inhibited NOX inhibitor-induced cell death in ARPE19/EBV cells. Furthermore, APX-115A-induced cell death mediated the activation of JNK and ERK. Finally, we confirmed the expression level of NOX4, and APX-115A induced cell death of EBV-infected human primary retina epithelial cells and the activation of JNK and ERK.

CONCLUSION

Taken together, these our results suggest that APX-115A could be a therapeutic agent for treating EBV-infected retinal cells or diseases by inhibiting LMP1-NOX4-ROS signaling.

The Epstein-Barr virus nuclear antigen-1 upregulates the cellular antioxidant defense to enable B-cell growth transformation and immortalization

Epstein-Barr virus (EBV) immortalizes human B-lymphocytes and is implicated in the pathogenesis of lymphoid and epithelial cell malignancies. The EBV nuclear antigen (EBNA)-1 induces the accumulation of reactive oxygen species (ROS), which enables B-cell immortalization but causes oxidative DNA damage and triggers antiproliferative DNA damage responses. By comparing pairs of EBV-negative and -positive tumor cell lines we found that, while associated with the accumulation of oxidized nucleotides, EBV carriage promotes the concomitant activation of oxo-dNTP sanitization and purging pathways, including upregulation of the nucleoside triphosphatase mut-T homolog 1 (MTH1) and the DNA glycosylases 8-oxoguanine-glycosylase-1 (OGG1) and mut-Y homolog (MUTYH). Expression of EBNA1 was reversibly associated with transcriptional activation of this cellular response. DNA damage and apoptosis were preferentially induced in EBNA1-positive cell lines by treatment with MTH1 inhibitors, suggesting that virus carriage is linked to enhanced vulnerability to oxidative stress. MTH1, OGG1, and MUTYH were upregulated upon EBV infection in primary B-cells and treatment with MTH1 inhibitors prevented B-cell immortalization. These findings highlight an important role of the cellular antioxidant response in sustaining EBV infection, and suggests that targeting this cellular defense may offer a novel approach to antiviral therapy and could reduce the burden of EBV associated cancer.

Total Antioxidant Status (TAS), Superoxide Dismutase (SOD), and Glutathione Peroxidase (GPx) in Oropharyngeal Cancer Associated with EBV Infection

A growing number of studies reveal that oxidative stress is associated with viral infections or cancer development. However, there are few reports assessing the relationships between oxidative stress, viral infection, and carcinogenesis. The present study analyzed the level of total antioxidant status (TAS) as well as the activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD) in patients with oropharyngeal cancer both Epstein-Barr virus (EBV)-positive and EBV-negative in comparison with the control group. The correlations between these parameters and EBV type (wild-type LMP1 (wt-LMP1) or LMP1 with deletion (del-LMP1)), level of antibodies against EBV, the degree of tumor differentiation, and TNM classification were also investigated. Fresh frozen tumor tissue samples collected from 66 patients with oropharyngeal squamous cell carcinoma were tested using nested PCR assay for EBV DNA detection. Spectrophotometric methods were used to measure TAS values as well as SOD and GPx activities in homogenates of tissue, using diagnostic kits produced by Randox Laboratories. Sera from all individuals were investigated using ELISA method to detect the presence of Epstein-Barr virus capsid antigen (EBVCA) IgM and IgG, Epstein-Barr virus nuclear antigen (EBNA) IgG, and early antigen (EA) IgG antibodies. The level of TAS and activities of antioxidant enzymes (GPx and SOD) were significantly decreased in tissues with oropharyngeal cancer, particularly in EBV-positive cases. In 82.3% of patients, wt-LMP1 was detected. Significantly lower TAS, GPx, and SOD values were stated in patients infected with wild-type EBV. The presence of antibodies against early antigen (anti-EA) was detected in over 80% of patients, which suggests reactivation of EBV infection. The correlation between the degree of tumor differentiation and TN classification, especially in EBV-positive patients, was also observed. Determination of these parameters may be useful in evaluating tumor burden in patients with various stages of oropharyngeal cancer and could be an important prognostic factor. Future studies are needed to understand the role of EBV lytic reactivation induced by oxidative stress.

Epstein–Barr virus: overcoming the DNA damage response

Infections by DNA viruses including, Epstein–Barr virus (EBV), typically induce cellular DNA damage responses (DDR), in particular double-stranded break signaling. To avoid apoptosis associated with constitutive DDR signaling, downstream steps of this pathway must be inactivated. EBV has developed multiple ways of disabling the DDR using several different viral proteins expressed at various stages of EBV infection. Here the interplay between EBV and host DDRs is discussed at each stage of EBV infection, along with the EBV proteins and miRNAs that are known to interfere with DDR signaling. The newly discovered APOBEC editing of EBV DNA and protection from this mutation is also discussed.

p62-mediated Selective autophagy endows virus-transformed cells with insusceptibility to DNA damage under oxidative stress

DNA damage response (DDR) and selective autophagy both can be activated by reactive oxygen/nitrogen species (ROS/RNS), and both are of paramount importance in cancer development. The selective autophagy receptor and ubiquitin (Ub) sensor p62 plays a key role in their crosstalk. ROS production has been well documented in latent infection of oncogenic viruses including Epstein-Barr Virus (EBV). However, p62-mediated selective autophagy and its interplay with DDR have not been investigated in these settings. In this study, we provide evidence that considerable levels of p62-mediated selective autophagy are spontaneously induced, and correlate with ROS-Keap1-NRF2 pathway activity, in virus-transformed cells. Inhibition of autophagy results in p62 accumulation in the nucleus, and promotes ROS-induced DNA damage and cell death, as well as downregulates the DNA repair proteins CHK1 and RAD51. In contrast, MG132-mediated proteasome inhibition, which induces rigorous autophagy, promotes p62 degradation but accumulation of the DNA repair proteins CHK1 and RAD51. However, pretreatment with an autophagy inhibitor offsets the effects of MG132 on CHK1 and RAD51 levels. These findings imply that p62 accumulation in the nucleus in response to autophagy inhibition promotes proteasome-mediated CHK1 and RAD51 protein instability. This claim is further supported by the findings that transient expression of a p62 mutant, which is constitutively localized in the nucleus, in B cell lines with low endogenous p62 levels recaptures the effects of autophagy inhibition on CHK1 and RAD51 protein stability. These results indicate that proteasomal degradation of RAD51 and CHK1 is dependent on p62 accumulation in the nucleus. However, small hairpin RNA (shRNA)-mediated p62 depletion in EBV-transformed lymphoblastic cell lines (LCLs) had no apparent effects on the protein levels of CHK1 and RAD51, likely due to the constitutive localization of p62 in the cytoplasm and incomplete knockdown is insufficient to manifest its nuclear effects on these proteins. Rather, shRNA-mediated p62 depletion in EBV-transformed LCLs results in significant increases of endogenous RNF168-γH2AX damage foci and chromatin ubiquitination, indicative of activation of RNF168-mediated DNA repair mechanisms. Our results have unveiled a pivotal role for p62-mediated selective autophagy that governs DDR in the setting of oncogenic virus latent infection, and provide a novel insight into virus-mediated oncogenesis.

Down-regulation of intracellular reactive oxygen species attenuates P-glycoprotein-associated chemoresistance in Epstein-Barr virus-positive NK/T-cell lymphoma

Epstein-Barr virus (EBV)-positive extranodal NK/T-cell lymphoma is a rare and highly aggressive disease with a poor prognosis and strong resistance to anti-cancer drugs. Reactive oxygen species (ROS) are closely related to tumorigenesis and P-glycoprotein (P-gp) is highly expressed in various cancers. However, the exact relationship between ROS and P-gp in EBV-positive lymphoma remains unclear. In this study, we demonstrated that EBV latent infection induced intracellular ROS production and increased ROS levels triggered elevated P-gp expression, which resulted in strong resistance to existing anti-cancer drugs in EBV-positive lymphoma cell lines and in patients' tissue samples. We also verified that regulation of intracellular ROS reduced P-gp expression and function via inhibition of STAT1 phosphorylation. These results indicate that treatment with a ROS scavenger is a potential therapeutic strategy to overcome resistance to anti-cancer drugs by downregulating the expression of P-gp in EBV-positive NK/T-cell lymphoma.

Antioxidants: Positive or Negative Actors?

The term “antioxidant” is one of the most confusing definitions in biological/medical sciences. In chemistry, “antioxidant” is simply conceived “a compound that removes reactive species, mainly those oxygen-derived”, while in a cell context, the conceptual definition of an antioxidant is poorly understood. Indeed, non-clinically recommended antioxidants are often consumed in large amounts by the global population, based on the belief that cancer, inflammation and degenerative diseases are triggered by high oxygen levels (or reactive oxygen species) and that through blocking reactive species production, organic unbalances/disorders can be prevented and/or even treated. The popularity of these chemicals arises in part from the widespread public mistrust of allopathic medicine. In fact, reactive oxygen species play a dual role in dealing with different disorders, since they may contribute to disease onset and/or progression but may also play a key role in disease prevention. Further, the ability of the most commonly used supplements, such as vitamins C, E, selenium, and herbal supplements to decrease pathologic reactive oxygen species is not clearly established. Hence, the present review aims to provide a nuanced understanding of where current knowledge is and where it should go.

Oxeiptosis: a discreet way to respond to radicals

One of the best-studied cellular responses to toxic signals and pathogens is programmed cell death. Over the past years, it became apparent that the specific mechanisms of cell death have tremendous influence at both cellular and organismal level, highlighting the importance of sensors and pathways involved in this decision-making process. Central signalling molecules involved in a variety of cell death pathways are reactive oxygen species (ROS). However, the molecular mechanisms regulating differential responses and cellular fates to distinct ROS levels remain incompletely understood. Recently, we uncovered a caspase-independent cell-death pathway named 'oxeiptosis', which links the ROS sensing capacity of KEAP1 to a cell death pathway involving PGAM5 and AIFM1. Alike apoptosis, oxeiptosis is anti-inflammatory when activated by increased intracellular ROS levels and upon pathogens encounter. Here we discuss the potential impact of oxeiptosis in pathogens clearance and teratogenic cells.

Epstein-Barr Virus-Associated Malignancies: Roles of Viral Oncoproteins in Carcinogenesis

The Epstein–Barr virus (EBV) is the first herpesvirus identified to be associated with human cancers known to infect the majority of the world population. EBV-associated malignancies are associated with a latent form of infection, and several of the EBV-encoded latent proteins are known to mediate cellular transformation. These include six nuclear antigens and three latent membrane proteins (LMPs). In lymphoid and epithelial tumors, viral latent gene expressions have distinct pattern. In both primary and metastatic tumors, the constant expression of latent membrane protein 2A (LMP2A) at the RNA level suggests that this protein is the key player in the EBV-associated tumorigenesis. While LMP2A contributing to the malignant transformation possibly by cooperating with the aberrant host genome. This can be done in part by dysregulating signaling pathways at multiple points, notably in the cell cycle and apoptotic pathways. Recent studies also have confirmed that LMP1 and LMP2 contribute to carcinoma progression and that this may reflect the combined effects of these proteins on activation of multiple signaling pathways. This review article aims to investigate the aforementioned EBV-encoded proteins that reveal established roles in tumor formation, with a greater emphasis on the oncogenic LMPs (LMP1 and LMP2A) and their roles in dysregulating signaling pathways. It also aims to provide a quick look on the six members of the EBV nuclear antigens and their roles in dysregulating apoptosis.

Levels of oxidative stress biomarkers and bone resorption regulators in apical periodontitis lesions infected by Epstein-Barr virus

AIM

To investigate whether apical periodontitis lesions infected by Epstein-Barr virus (EBV) exhibit higher levels of oxidative stress biomarkers [8-hydroxydeoxyguanosine (8-OHdG) and oxidized glutathione (GSSG)] and bone resorption regulators [receptor activator of nuclear factor (NF-κB) ligand (RANKL) and osteoprotegerin (OPG)] compared to EBV-negative periapical lesions and healthy pulp tissues.

METHODOLOGY

The experimental group consisted of 30 EBV-positive and 30 EBV-negative periapical lesions collected in conjunction with apicoectomy. The pulp tissues of 20 impacted third molars were used as healthy controls. The qualitative and quantitative analysis of EBV was performed by nested and real-time polymerase chain reaction (PCR), respectively. The levels of RANKL and OPG were analysed by reverse transcriptase real-time PCR. The levels of 8-OHdG and GSSG were determined by enzyme-linked immunosorbent assay (ELISA). Mann-Whitney U-test and Spearman's correlation were used for statistical analysis.

RESULTS

The levels of RANKL, OPG, 8-OHdG and GSSG were significantly higher in apical periodontitis lesions compared to healthy pulp controls (P = 0.001, P < 0.001, P < 0.001 and P < 0.05, respectively). RANKL and OPG mRNA expression was significantly higher in EBV-positive compared to EBV-negative periapical lesions (P < 0.05). There was no significant correlation between EBV copy numbers and levels of RANKL, OPG, 8OH-dG and GSSG in apical periodontitis.

CONCLUSION

Levels of bone resorption regulators and oxidative stress biomarkers were increased in apical periodontitis compared to healthy pulp tissues. EBV-positive periapical lesions exhibited higher levels of RANKL and OPG compared to EBV-negative periapical lesions. EBV may contribute to progression of apical periodontitis via enhanced production of bone resorption regulators.

LIMD1 is induced by and required for LMP1 signaling, and protects EBV-transformed cells from DNA damage-induced cell death

LIMD1 (LIM domain-containing protein 1) is considered as a tumor suppressor, being deregulated in many cancers to include hematological malignancies; however, very little is known about the underlying mechanisms of its deregulation and its roles in carcinogenesis. Epstein-Barr Virus (EBV) is associated with a panel of malignancies of lymphocytic and epithelial origin. Using high throughput expression profiling, we have previously identified LIMD1 as a common marker associated with the oncogenic transcription factor IRF4 in EBV-related lymphomas and other hematological malignancies. In this study, we have identified potential conserved IRF4- and NFκB-binding motifs in the LIMD1 gene promoter, and both are demonstrated functional by promoter-reporter assays. We further show that LIMD1 is partially upregulated by EBV latent membrane protein 1 (LMP1) via IRF4 and NFκB in EBV latency. As to its role in the setting of EBV latent infection, we show that LIMD1 interacts with TRAF6, a crucial mediator of LMP1 signal transduction. Importantly, LIMD1 depletion impairs LMP1 signaling and functions, potentiates ionomycin-induced DNA damage and apoptosis, and inhibits p62-mediated selective autophagy. Taken together, these results show that LIMD1 is upregulated in EBV latency and plays an oncogenic role rather than that of a tumor suppressor. Our findings have identified LIMD1 as a novel player in EBV latency and oncogenesis, and open a novel research avenue, in which LIMD1 and p62 play crucial roles in linking DNA damage response (DDR), apoptosis, and autophagy and their potential interplay during viral oncogenesis.

Glutaredoxin 3 promotes nasopharyngeal carcinoma growth and metastasis via EGFR/Akt pathway and independent of ROS

Glutaredoxin 3 (GLRX3) is antioxidant enzyme, maintaining a low level of ROS, thus contributing to the survival and metastasis of several types of cancer. However, the expression and functions of GLRX3 have not been addressed in nasopharyngeal carcinoma (NPC). In this study, we found that GLRX3 was overexpressed in NPC. Knockdown of GLRX3 in NPC cell lines inhibited proliferation in vitro, tumorignesis in vivo, and colony formation. In addition, GLRX3 knockdown decreased the migration and invasion capacity of NPC cells by reversing the epithelial-mesenchymal transition (EMT). Furthermore, stabilization of GLRX3 was positively related to with epidermal growth factor receptor (EGFR) expression and negatively with ROS generation. Phosphorylation of Akt, a key downstream effector, was induced by EGFR signaling but did not rely on increasing ROS level in NPC cells. GLRX3 might be an oncoprotein in NPC, playing important roles in increasing redox reaction and activating EGFR/ Akt signals, so it may be a therapeutic target for NPC.

Targeting the duality of cancer

Cancer is the second leading cause of death in the United States, and is an increasing cause of death in the developing world. While there is great heterogeneity in the anatomic site and mutations involved in human cancer, there are common features, including immortal growth, angiogenesis, apoptosis evasion, and other features, that are common to most if not all cancers. However, new features of human cancers have been found as a result of clinical use of novel “targeted therapies,” angiogenesis inhibitors, and immunotherapies, including checkpoint inhibitors. These findings indicate that cancer is a moving target, which can change signaling and metabolic features based upon the therapies offered. It is well-known that there is significant heterogeneity within a tumor and it is possible that treatment might reduce the heterogeneity as a tumor adapts to therapy and, thus, a tumor might be synchronized, even if there is no major clinical response. Understanding this concept is important, as concurrent and sequential therapies might lead to improved tumor responses and cures. We posit that the repertoire of tumor responses is both predictable and limited, thus giving hope that eventually we can be more effective against solid tumors. Currently, among solid tumors, we observe a response of 1/3 of tumors to immunotherapy, perhaps less to angiogenesis inhibition, a varied response to targeted therapies, with relapse and resistance being the rule, and a large fraction being insensitive to all of these therapies, thus requiring the older therapies of chemotherapy, surgery, and radiation. Tumor phenotypes can be seen as a continuum between binary extremes, which will be discussed further. The biology of cancer is undoubtedly more complex than duality, but thinking of cancer as a duality may help scientists and oncologists discover optimal treatments that can be given either simultaneously or sequentially.

The role of metabolic reprogramming in γ-herpesvirus-associated oncogenesis

The γ-herpesviruses, EBV and KSHV, are closely associated with a number of human cancers. While the signal transduction pathways exploited by γ-herpesviruses to promote cell growth, survival and transformation have been reported, recent studies have uncovered the impact of γ-herpesvirus infection on host cell metabolism. Here, we review the mechanisms used by γ-herpesviruses to induce metabolic reprogramming in host cells, focusing on their ability to modulate the activity of metabolic regulators and manipulate metabolic pathways. While γ-herpesviruses alter metabolic phenotypes as a means to support viral infection and long-term persistence, this modulation can inadvertently contribute to cancer development. Strategies that target deregulated metabolic phenotypes induced by γ-herpesviruses provide new opportunities for therapeutic intervention.

Comparative genomic expression signatures of signal transduction pathways and targets in paediatric Burkitt lymphoma: a Children's Oncology Group report

Burkitt lymphoma (BL) is the most common histological subtype of non-Hodgkin lymphoma (NHL) in children and adolescents. Through the introduction of short intensive multi-agent chemoimmunotherapy, survival has improved significantly over the past 30 years. However, this successful approach is limited by significant chemotherapy-induced acute toxicity and risk of developing resistant disease, demonstrating the need to identify less toxic and targeted therapies. We analysed the comparative genomic signature and targetable signalling pathways in paediatric BL (PEBL) samples from the Children's Oncology Group study (ANHL01P1) by genomic profiling and selected genes were confirmed by quantitative real time polymerase chain reaction. These results were compared to PEBL samples from public databases and utilised the Gene Expression Omnibus (GEO) Series (GSE) 10172 and 4475 (n = 16), and 4732 (n = 15). Three hundred and seventy-six genes (approximately 25%) were similarly expressed among three PEBL sample groups. Several target genes in Toll-like receptor signalling, JAK-STAT signalling and MAPK signalling were significantly overexpressed in PEBL. In addition, several tyrosine kinases, including Bruton tyrosine kinase, protein tyrosine phosphatase and histone deacetylase inhibitor were highly expressed in PEBL. These pre-clinical results suggest that specific signal transduction pathways are overly expressed in PEBL and several pathways could serve as potential future therapeutic targets.

Epstein-Barr virus infection induces bone resorption in apical periodontitis via increased production of reactive oxygen species

Chronic inflammatory processes in periapical tissues caused by etiological agents of endodontic origin lead to apical periodontitis. Apart from bacteria, two herpesviruses, Epstein-Barr virus (EBV) and Human cytomegalovirus (HCMV) are recognized as putative pathogens in apical periodontitis. Although previous reports suggest the involvement of EBV in the pathogenesis of apical periodontitis, its exact role in periapical bone resorption has not yet been fully elucidated. We hypothesize that EBV infection in apical periodontitis is capable of inducing periapical bone resorption via stimulation of reactive oxygen species (ROS) overproduction. Increased levels of ROS induce expression of receptor activator of nuclear factor kappa B (NF-κB) ligand (RANKL). RANKL binding to receptor activator of nuclear factor κB (RANK) present on the surface of preosteoclasts induces their maturation and activation which consequently leads to bone resorption. The potential benefit of antiviral and antioxidant-based therapies in periapical bone resorption treatment remains to be assessed.

Chronic oxidative stress increases the integration frequency of foreign DNA and human papillomavirus 16 in human keratinocytes

Cervical cancer is the second most common cancer, and the fourth most common cause of cancer death in women worldwide. Nearly all of these cases are caused by high-risk HPVs (HR HPVs), of which HPV16 is the most prevalent type. In most cervical cancer specimens, HR HPVs are found integrated into the human genome, indicating that integration is a key event in cervical tumor development. An understanding of the mechanisms that promote integration may therefore represent a unique opportunity to intercept carcinogenesis. To begin identifying these mechanisms, we tested the hypothesis that chronic oxidative stress (OS) induced by virus- and environmentallymediated factors can induce DNA damage, and thereby increase the frequency with which HPV integrates into the host genome. We found that virus-mediated factors are likely involved, as expression of E6*, a splice isoform of HPV16 E6, increased the levels of reactive oxygen species (ROS), caused oxidative DNA damage, and increased the frequency of plasmid DNA integration as assessed by colony formation assays. To assess the influence of environmentally induced chronic OS, we used L-Buthionine-sulfoximine (BSO) to lower the level of the intracellular antioxidant glutathione. Similar to our observations with E6*, glutathione depletion by BSO also increased ROS levels, caused oxidative DNA damage and increased the integration frequency of plasmid DNA. Finally, under conditions of chronic OS, we were able to induce and characterize a few independent events in which episomal HPV16 integrated into the host genome of cervical keratinocytes. Our results support a chain of events leading from induction of oxidative stress, to DNA damage, to viral integration, and ultimately to carcinogenesis.

Effects of Human Mesenchymal Stem Cells Transduced with Superoxide Dismutase on Imiquimod-Induced Psoriasis-Like Skin Inflammation in Mice

AIMS

The immunomodulatory and anti-inflammatory properties of mesenchymal stem cells (MSCs) have been proposed in several autoimmune diseases and successfully tested in animal models, but their contribution to psoriasis and underlying pathways remains elusive. Likewise, an increased or prolonged presence of reactive oxygen species and aberrant antioxidant systems in skin are known to contribute to the development of psoriasis and therefore effective antioxidant therapy is highly required. We explored the feasibility of using extracellular superoxide dismutase (SOD3)-transduced allogeneic MSCs as a novel therapeutic approach in a mouse model of imiquimod (IMQ)-induced psoriasis-like inflammation and investigated the poorly understood underlying mechanism. In addition, the chronicity and late-phase response of inflammation were evaluated during continued activation of antigen receptors by applying a booster dose of IMQ.

RESULTS

Subcutaneous injection of allogeneic SOD3-transduced MSCs significantly prevented psoriasis development in our IMQ-induced mouse model, likely through a suppression of proliferation and infiltration of various effector cells into skin with a concomitant modulated cytokine and chemokine expression and inhibition of signaling pathways such as toll-like receptor-7, nuclear factor-kappa B, p38 mitogen-activated kinase, and Janus kinase-signal transducer and activator of transcription, as well as adenosine receptor activation.

INNOVATION AND CONCLUSION

Our data offer a novel therapeutic approach to chronic inflammatory skin diseases such as psoriasis by leveraging immunomodulatory effects of MSCs as well as SOD3 expression.

A systematic review of known mechanisms of hydroxyurea-induced fetal hemoglobin for treatment of sickle cell disease

AIM

To report on molecular mechanisms of fetal hemoglobin (HbF) induction by hydroxyurea (HU) for the treatment of sickle cell disease.

STUDY DESIGN

Systematic review.

RESULTS

Studies have provided consistent associations between genomic variations in HbF-promoting loci and variable HbF level in response to HU. Numerous signal transduction pathways have been implicated, through the identification of key genomic variants in BCL11A, HBS1L-MYB, SAR1 or XmnI polymorphism that predispose the response to the treatment, and signal transduction pathways that modulate γ-globin expression (cAMP/cGMP; Giα/c-Jun N-terminal kinase/Jun; methylation and miRNA). Three main molecular pathways have been reported: i) Epigenetic modifications, transcriptional events and signaling pathways involved in HU-mediated response, ii) Signaling pathways involving HU-mediated response and iii) Post-transcriptional pathways (regulation by miRNAs).

CONCLUSIONS

The complete picture of HU-mediated mechanisms of HbF production in Sickle Cell Disease remains elusive. Research on post-transcriptional mechanisms could lead to therapeutic targets that may minimize alterations to the cellular transcriptome.

The antioxidant paradox: what are antioxidants and how should they be used in a therapeutic context for cancer

So-called antioxidants have yet to make a clinical impact on the treatment of human cancer. The reasons for this failure are several. First, many agents that are called antioxidants are truly antioxidants at a given dose, but this dose may not have been given in clinical trials. Second, many agents are not antioxidants at all. Third, not all tumors use reactive oxygen as a signaling mechanism. Finally, reactive oxygen inhibition is often insufficient to kill or regress a tumor cell by itself, but requires sequential introduction of a therapeutic agent for maximal effect. We hope to provide a framework for the logical use of these agents in cancer.

LMP1 Increases Expression of NADPH Oxidase (NOX) and Its Regulatory Subunit p22 in NP69 Nasopharyngeal Cells and Makes Them Sensitive to a Treatment by a NOX Inhibitor

Oxidative stress is thought to contribute to cancer development. Epstein–Barr virus (EBV) and its encoded oncoprotein, latent membrane protein 1 (LMP1), are closely associated with the transformation of nasopharyngeal carcinoma (NPC) and Burkitt’s lymphoma (BL). In this study, we used LMP1-transformed NP cells and EBV-related malignant cell lines to assess the effects of LMP1 on reactive oxygen species (ROS) accumulation and glycolytic activity. Using NPC tissue samples and a tissue array to address clinical implications, we report that LMP1 activates NAD(P)H oxidases to generate excessive amount of ROS in EBV-related malignant diseases. By evaluating NAD(P)H oxidase (NOX) subunit expression, we found that the expression of the NAD(P)H oxidase regulatory subunit p22^phox was significantly upregulated upon LMP1-induced transformation. Furthermore, this upregulation was mediated by the c-Jun N-terminal kinase (JNK) pathway. In addition, LMP1 markedly stimulated anaerobic glycolytic activity through the PI3K/Akt pathway. Additionally, in both NPC cells and tissue samples, p22^phox expression correlated with LMP1 expression. The NAD(P)H oxidase inhibitor diphenyleneiodonium (DPI) also exerted a marked cytotoxic effect in LMP1-transformed and malignant cells, providing a novel strategy for anticancer therapy.

Down Regulation of CLDND1 Induces Apoptosis in Breast Cancer Cells

Identification of targets for apoptosis induction is important to provide novel therapeutic approaches in breast cancer. Our earlier studies showed that down regulation of protein kinase C δ (PKCδ) induces death in breast cancer cells. In this study we set out to identify previously unrecognized apoptosis regulators in breast cancer cells. To identify candidates, global expression analysis with microarray was performed after down regulation of PKCδ in the basal-like breast cancer cell lines MDA-MB-231, MDA-MB-468 and BT-549. Genes that were down regulated in all cell lines were further studied for survival-supporting effects. The claudin-like CLDND1 was singled out since several independent siRNAs targeting CLDND1 induced cell death in several cell lines. The cell death induced by CLDND1 knockdown was caspase-dependent, suggesting induction of apoptosis. Nuclear fragmentation, cleavage of caspase-3 and PARP and release of cytochrome C from the mitochondria upon CLDND1 depletion demonstrated involvement of the intrinsic apoptotic pathway. Inhibition of MEK1/2 and JNK further potentiated the cell death induction by CLDND1 knockdown. However, CLDND1 down regulation augmented ERK1/2 phosphorylation, which thereby may protect against the apoptosis inducing effects of CLDND1 down regulation. A concomitant inhibition of MEK1/2 suppresses the ERK1/2 phosphorylation and markedly potentiates the cell death following CLDND1 siRNA treatment. There is today little information on the function of CLDND1. These data provide novel information on CLDND1 and highlight it as a novel survival factor in basal-like breast cancer cell lines.

Diphenylene iodonium interferes with cell cycle progression and induces apoptosis by modulating NAD(P)H oxidase/ROS/cell cycle regulatory pathways in Burkitt's lymphoma cells

Infection with Epstein-Barr virus (EBV) and its encoded latent membrane protein 1 (LMP1) play oncogenic roles in Burkitt's lymphoma (BL). Flow cytometry was used to measure cellular reactive oxygen species (ROS) concentrations, and cellular lactate generation and diphenylene iodonium (DPI) cytotoxicity were determined by analyzing lactate concentrations and cell viability. We also measured NAD(P)H oxidase (NOX) activity. Reverse transcriptase PCR and qPCR assays were used to analyze LMP1 levels, and protein expression was measured by immunoblotting. In the present study, EBV was able to induce NOX activity and ROS generation in the BL cells. Inhibition of NOX activity by DPI suppressed ROS levels and elevated lactate levels. DPI treatment first resulted in a G2-M phase cell cycle arrest and then induced significant apoptosis. Immunoblot analysis demonstrated that DPI suppressed the expression of c-Myc and Cdc25A within 6 h, which may have caused the cell cycle arrest. Collectively, these findings indicate a close relationship between EBV infection and NOX activation, permitting a deeper understanding of ROS inhibition in cell cycle regulation and providing a novel therapeutic target for BL treatment.

EBNA1

Epstein-Barr nuclear antigen 1 (EBNA1) plays multiple important roles in EBV latent infection and has also been shown to impact EBV lytic infection. EBNA1 is required for the stable persistence of the EBV genomes in latent infection and activates the expression of other EBV latency genes through interactions with specific DNA sequences in the viral episomes. EBNA1 also interacts with several cellular proteins to modulate the activities of multiple cellular pathways important for viral persistence and cell survival. These cellular effects are also implicated in oncogenesis, suggesting a direct role of EBNA1 in the development of EBV-associated tumors.