NF-kappaB-mediated modulation of inducible nitric oxide synthase activity controls induction of the Epstein-Barr virus productive cycle by transforming growth factor beta 1

The role of nitric oxide synthase/ nitric oxide in infection-related cancers: Beyond antimicrobial activity

As a free radical and endogenous effector molecule, mammalian endogenous nitric oxide (NO) is mainly derived from nitric oxide synthase (NOS) via L-arginine. NO participates in normal physiological reactions and provides immune responses to prevent the invasion of foreign bacteria. However, NO also has complex and contradictory biological effects. Abnormal NO signaling is involved in the progression of many diseases, such as cancer. In the past decades, cancer research has been closely linked with NOS/ NO, and many tumors with poor prognosis are associated with high expression of NOS. In this review, we give a overview of the biological effects of NOS/ NO. Then we focus on the oncogenic role of iNOS/ NO in HPV, HBV, EBV and H. pylori related tumors. In fact, there is growing evidence that iNOS could be used as a potential therapeutic target in cancer therapy. We emphasize that the pro-tumor effect of NOS/ NO is greater than the anti-tumor effect.

An integrated approach to the structural characterization, long-term toxicological and anti-inflammatory evaluation of Pterospermum rubiginosum bark extract

ETHNOPHARMACOLOGICAL RELEVANCE OF STUDY

Pterospermum rubiginosum is an evergreen plant in Western Ghats, India, used by traditional tribal healers due to its excellent biological potential for treating inflammation and pain relief procedures. The bark extract is also consumed to relieve the inflammatory changes at the bone fractured site. The traditional medicinal plant in India have to be characterized for its diverse phytochemical moieties, its interactive multiple target sites, and to reveal the hidden molecular mechanism behind the biological potency.

AIM OF THE STUDY

The study focussed on plant material characterization, computational analysis (prediction study), toxicological screening (In vivo), and anti-inflammatory evaluation of P. rubiginosum methanolic bark extracts (PRME) in LPS-induced RAW 264.7 cells.

MATERIALS AND METHODS

The pure compound isolation of PRME and their biological interactions were used to predict the bioactive components, molecular targets, and molecular pathways of PRME in inhibiting inflammatory mediators. The anti-inflammatory effects of PRME extract were evaluated in the lipopolysaccharide (LPS)-induced RAW264.7 macrophage cell model. The toxicity evaluation of PRME was performed in healthy 30 Sprague-Dawley experimental rats, were randomly divided into five groups for toxicological evaluation for 90 days. The tissue levels of oxidative stress and organ toxicity markers were measured using the ELISA method. Nuclear magnetic resonance spectroscopy (NMR) was performed to characterize the bioactive molecules.

RESULTS

Structural characterization revealed the presence of vanillic acid, 4-O-methyl gallic acid, E-resveratrol, gallocatechin, 4'-O-methyl gallocatechin, and catechin. Molecular docking of NF-kB exhibited significant interactions with vanillic acid and 4-O-methyl gallic acid with binding energy -351.159 Kcal/Mol and -326.5505 Kcal/Mol, respectively. The PRME-treated animals showed an increase in total GPx and antioxidant levels (SOD and catalase). Histopathological examination revealed no variation in the liver, renal and splenic tissue's cellular pattern. PRME inhibited the pro-inflammatory parameters (IL-1β, IL-6, and TNF-α) in LPS-induced RAW 264.7 cells. The protein level of TNF-α and NF-kB protein expression study brought out a notable reduction and exhibited a good correlation with the gene expression study.

CONCLUSION

The current study establishes the therapeutic potential of PRME as an effective inhibitory agent against LPS-activated RAW 264.7 cells induced inflammatory mediators. Long-term toxicity evaluation on SD rats confirmed the non-toxic nature of PRME up to 250mg/body weight for 3 months.

Molecular Basic of Pharmacotherapy of Cytokine Imbalance as a Component of Intervertebral Disc Degeneration Treatment

Intervertebral disc degeneration (IDD) and associated conditions are an important problem in modern medicine. The onset of IDD may be in childhood and adolescence in patients with a genetic predisposition. With age, IDD progresses, leading to spondylosis, spondylarthrosis, herniated disc, spinal canal stenosis. One of the leading mechanisms in the development of IDD and chronic back pain is an imbalance between pro-inflammatory and anti-inflammatory cytokines. However, classical therapeutic strategies for correcting cytokine imbalance in IDD do not give the expected response in more than half of the cases. The purpose of this review is to update knowledge about new and promising therapeutic strategies based on the correction of the molecular mechanisms of cytokine imbalance in patients with IDD. This review demonstrates that knowledge of the molecular mechanisms of the imbalance between pro-inflammatory and anti-inflammatory cytokines may be a new key to finding more effective drugs for the treatment of IDD in the setting of acute and chronic inflammation.

The epinephrine-induced PGE2 reduces Na+/K+ ATPase activity in Caco-2 cells via PKC, NF-κB and NO

We showed previously an epinephrine-induced inhibition of the Na⁺/K⁺ ATPase in Caco-2 cells mediated via PGE2. This work is an attempt to further elucidate mediators downstream of PGE2 and involved in the observed inhibitory effect. The activity of the Na⁺/K⁺ ATPase was assayed by measuring the amount of inorganic phosphate liberated in presence and absence of ouabain, a specific inhibitor of the enzyme. Changes in the protein expression of the Na⁺/K⁺ ATPase were investigated by western blot analysis which revealed a significant decrease in the abundance of the ATPase in plasma membranes. Treating the cells with epinephrine or PGE2 in presence of SC19220, a blocker of EP1 receptors abolished completely the effect of the hormone and the prostaglandin while the effect was maintained unaltered in presence of antagonists to all other receptors. Treatment with calphostin C, PTIO, ODQ or KT5823, respective inhibitors of PKC, NO, soluble guanylate cyclase and PKG, abrogated completely the effect of epinephrine and PGE2, suggesting an involvement of these mediators. A significant inhibition of the ATPase was observed when cells were treated with PMA, an activator of PKC or with 8-Br-cGMP, a cell permeable cGMP analogue. PMA did reduce the protein expression of IκB, as shown by western blot analysis, and its effect on the ATPase was not manifested in presence of an inhibitor of NF-κB while that of SNAP, a nitric oxide donor, was not affected. The results infer that NF-κB is downstream PKC and upstream NO. The data support a pathway in which epinephrine induces the production of PGE2 which binds to EP1 receptors and activates PKC and NF-κB leading to NO synthesis. The latter activates soluble guanylate cyclase resulting in cGMP production and activation of PKG which through direct or indirect phosphorylation inhibits the Na⁺/K⁺ ATPase by inducing its internalization.

IL-10 knockdown with siRNA enhances the efficacy of Doxorubicin chemotherapy in EBV-positive tumors by inducing lytic cycle via PI3K/p38 MAPK/NF-kB pathway

High levels of IL-10 expression in Epstein-Barr virus (EBV) associated tumors have been reported and it is likely to be important for maintaining EBV latency and EBV-associated tumors. The switch from the latent form of EBV to the lytic form in tumor cells can lead to tumor cell lysis. Here, we found that knockdown of IL-10 induced EBV lytic replication. Subsequently, we demonstrated that IL-10 knockdown activated BZLF1 promoter through PI3K-p38 MAPK-NF-κB signaling pathway. Interestingly, we verified that VEGF-A was required for IL-10 knockdown to activate PI3K signaling and the accompanying EBV lytic induction. Exogenous recombinant human VEGF-A induced PI3K activation and EBV lytic infection, and inhibition of VEGF-A signaling prevented the PI3K/AKT phosphorylation and EBV reactivation responded to IL-10 knockdown. Most importantly, IL-10 knockdown synergized with chemotherapeutic agent Doxorubicin to kill EBV associated tumor cells in vitro and repress EBV-positive tumor growth in vivo. Our results suggest that inhibition of IL-10 has the potential to serve as a new supplemental strategy for the treatment of EBV-associated tumors.

Alterations in cellular and viral microRNA and cellular gene expression in Marek's disease virus-transformed T-cell lines treated with sodium butyrate

A shared feature of herpesviruses is their ability to enter a latent state following an initially lytic infection. Marek's disease virus serotype 1 (MDV-1) is an oncogenic avian herpesvirus. Small RNA profiling studies have suggested that microRNAs (miRNAs) are involved in viral latency. Sodium butyrate treatment is known to induce herpesvirus reactivation. The present study was undertaken to determine transcriptome and miRNome changes induced by sodium butyrate in 2 MDV-transformed cell lines, RP2 and CU115. In the first 24 h post-treatment, microarray analysis of transcriptional changes in cell lines RP2 and CU115 identified 137 and 114 differentially expressed genes, respectively. Small RNA deep-sequencing analysis identified 17 cellular miRNAs that were differentially expressed. The expression of MDV-encoded miRNAs was also altered upon treatment. Many of the genes and miRNAs that are differentially expressed are involved in regulation of the cell cycle, mitosis, DNA metabolism, and lymphocyte differentiation.

Molecular Mechanisms of H. pylori-Induced DNA Double-Strand Breaks

Infections contribute to carcinogenesis through inflammation-related mechanisms. H. pylori infection is a significant risk factor for gastric carcinogenesis. However, the molecular mechanism by which H. pylori infection contributes to carcinogenesis has not been fully elucidated. H. pylori-associated chronic inflammation is linked to genomic instability via reactive oxygen and nitrogen species (RONS). In this article, we summarize the current knowledge of H. pylori-induced double strand breaks (DSBs). Furthermore, we provide mechanistic insight into how processing of oxidative DNA damage via base excision repair (BER) leads to DSBs. We review recent studies on how H. pylori infection triggers NF-κB/inducible NO synthase (iNOS) versus NF-κB/nucleotide excision repair (NER) axis-mediated DSBs to drive genomic instability. This review discusses current research findings that are related to mechanisms of DSBs and repair during H. pylori infection.

Differentiation-Dependent LMP1 Expression Is Required for Efficient Lytic Epstein-Barr Virus Reactivation in Epithelial Cells

Epstein-Barr virus (EBV)-associated diseases of epithelial cells, including tumors that have latent infection, such as nasopharyngeal carcinoma (NPC), and oral hairy leukoplakia (OHL) lesions that have lytic infection, frequently express the viral latent membrane protein 1 (LMP1). In lytically infected cells, LMP1 expression is activated by the BRLF1 (R) immediate early (IE) protein. However, the mechanisms by which LMP1 expression is normally regulated in epithelial cells remain poorly understood, and its potential roles in regulating lytic reactivation in epithelial cells are as yet unexplored. We previously showed that the differentiation-dependent cellular transcription factors KLF4 and BLIMP1 induce lytic EBV reactivation in epithelial cells by synergistically activating the two EBV immediate early promoters (Zp and Rp). Here we show that epithelial cell differentiation also induces LMP1 expression. We demonstrate that KLF4 and BLIMP1 cooperatively induce the expression of LMP1, even in the absence of the EBV IE proteins BZLF1 (Z) and R, via activation of the two LMP1 promoters. Furthermore, we found that differentiation of NOKs-Akata cells by either methylcellulose suspension or organotypic culture induces LMP1 expression prior to Z and R expression. We show that LMP1 enhances the lytic infection-inducing effects of epithelial cell differentiation, as well as 12-O-tetradecanoylphorbol-13-acetate (TPA) and sodium butyrate treatment, in EBV-infected epithelial cells by increasing expression of the Z and R proteins. Our results suggest that differentiation of epithelial cells activates a feed-forward loop in which KLF4 and BLIMP1 first activate LMP1 expression and then cooperate with LMP1 to activate Z and R expression.IMPORTANCE The EBV protein LMP1 is expressed in EBV-associated epithelial cell diseases, regardless of whether these diseases are due to lytic infection (such as oral hairy leukoplakia) or latent infection (such as nasopharyngeal carcinoma). However, surprisingly little is known about how LMP1 expression is regulated in epithelial cells, and there are conflicting reports about whether it plays any role in regulating viral lytic reactivation. In this study, we show that epithelial cell differentiation induces LMP1 expression by increasing expression of two cellular transcription factors (KLF4 and BLIMP1) which cooperatively activate the two LMP1 promoters. We also demonstrate that LMP1 promotes efficient lytic reactivation in EBV-infected epithelial cells by enhancing expression of the Z and R proteins. Thus, in EBV-infected epithelial cells, LMP1 expression is promoted by differentiation and positively regulates lytic viral reactivation.

Protective role of propofol on the kidney during early unilateral ureteral obstruction through inhibition of epithelial-mesenchymal transition

Unilateral ureteral obstruction (UUO) induces functional and pathological changes in the obstructed kidney. Inducible nitric oxide synthase (iNOS) expression is high inearly UUO mouse kidney, which is accompanied with fibrosis. Propofol has preventive effects against renal injury by downregulating iNOS expression in UUO mouse models. However, the role of propofol in kidney fibrosis progression has not been reported. We explored the therapeutic potential and possible mechanisms of action of propofol in kidney fibrosis using a UUO mouse model. Herein, mice anesthetized with propofol or sevoflurane underwent UUO induction. Serum and kidney sections were collected 5 and 28 days post-operation for histological, morphometric, immunofluorescence, microRNA analyses; quantitative PCR and western blotting. In vivo, the effect and mechanism of propofol on epithelial-mesenchymal transition (EMT), transforming growth factor β (TGF-β) signaling and miR-155 levels were detected in cultured HK-2 cells. We found that propofol significantly suppressed UUO-induced kidney fibrosis, which was associated with TGF-β/Smad3 signaling, EMT, and iNOS-NO production. MiR-155 levels were higher in UUO mouse kidneys; compared with sevoflurane, propofol suppressed miR-155 levels. However, in late UUO, propofol could not prevent kidney fibrosis or suppress EMT and miR-155. The in vitro results showed that propofol suppressed TGF-β1-induced EMT by regulating miR-155 levels. As a conclusion, in early UUO mice, propofol may inhibit TGF-β1 expression and NO-iNOS production, consequently inhibiting EMT and kidney fibrosis by regulating miR-155 levels, and might be a new protective agent against kidney injury during surgery and in therapy to prevent kidney fibrosis.

Characterization of a c-Rel Inhibitor That Mediates Anticancer Properties in Hematologic Malignancies by Blocking NF-κB-Controlled Oxidative Stress Responses

NF-κB plays a variety of roles in oncogenesis and immunity that may be beneficial for therapeutic targeting, but strategies to selectively inhibit NF-κB to exert antitumor activity have been elusive. Here, we describe IT-901, a bioactive naphthalenethiobarbiturate derivative that potently inhibits the NF-κB subunit c-Rel. IT-901 suppressed graft-versus-host disease while preserving graft-versus-lymphoma activity during allogeneic transplantation. Further preclinical assessment of IT-901 for the treatment of human B-cell lymphoma revealed antitumor properties in vitro and in vivo without restriction to NF-κB-dependent lymphoma. This nondiscriminatory, antilymphoma effect was attributed to modulation of the redox homeostasis in lymphoma cells resulting in oxidative stress. Moreover, NF-κB inhibition by IT-901 resulted in reduced stimulation of the oxidative stress response gene heme oxygenase-1, and we demonstrated that NF-κB inhibition exacerbated oxidative stress induction to inhibit growth of lymphoma cells. Notably, IT-901 did not elicit increased levels of reactive oxygen species in normal leukocytes, illustrating its cancer selective properties. Taken together, our results provide mechanistic insight and preclinical proof of concept for IT-901 as a novel therapeutic agent to treat human lymphoid tumors and ameliorate graft-versus-host disease.

Inducible nitric oxide synthase (iNOS) regulatory region variation in non-human primates

Inducible nitric oxide synthase (iNOS) is an enzyme that plays a key role in intracellular immune response against respiratory infections. Since various species of nonhuman primates exhibit different levels of susceptibility to infectious respiratory diseases, and since variation in regulatory regions of genes is thought to play a key role in expression levels of genes, two candidate regulatory regions of iNOS were mapped, sequenced, and compared across five species of nonhuman primates: African green monkeys (Chlorocebus sabaeus), pig-tailed macaques (Macaca nemestrina), cynomolgus macaques (Macaca fascicularis), Indian rhesus macaques (Macaca mulatta), and Chinese rhesus macaques (M. mulatta). In addition, we conducted an in silico analysis of the transcription factor binding sites associated with genetic variation in these two candidate regulatory regions across species. We found that only one of the two candidate regions showed strong evidence of involvement in iNOS regulation. Specifically, we found evidence of 13 conserved binding site candidates linked to iNOS regulation: AP-1, C/EBPB, CREB, GATA-1, GATA-3, NF-AT, NF-AT5, NF-κB, KLF4, Oct-1, PEA3, SMAD3, and TCF11. Additionally, we found evidence of interspecies variation in binding sites for several regulatory elements linked to iNOS (GATA-3, GATA-4, KLF6, SRF, STAT-1, STAT-3, OLF-1 and HIF-1) across species, especially in African green monkeys relative to other species. Given the key role of iNOS in respiratory immune response, the findings of this study might help guide the direction of future studies aimed to uncover the molecular mechanisms underlying the increased susceptibility of African green monkeys to several viral and bacterial respiratory infections.

Regulation of the latent-lytic switch in Epstein-Barr virus

Epstein-Barr virus (EBV) infection contributes to the development of several different types of human malignancy, including Burkitt lymphoma, Hodgkin lymphoma, and nasopharyngeal carcinoma. As a herpesvirus, EBV can establish latent or lytic infection in cells. EBV-positive tumors are composed almost exclusively of cells with latent EBV infection. Strategies for inducing the lytic form of EBV infection in tumor cells are being investigated as a potential therapy for EBV-positive tumors. In this article, we review how cellular and viral proteins regulate the latent-lytic EBV switch in infected B cells and epithelial cells, and discuss how harnessing lytic viral reactivation might be used therapeutically.

Microtubule depolymerization activates the Epstein–Barr virus lytic cycle through protein kinase C pathways in nasopharyngeal carcinoma cells

Elevated levels of antibodies against Epstein–Barr virus (EBV) and the presence of viral DNA in plasma are reliable biomarkers for the diagnosis of nasopharyngeal carcinoma (NPC) in high-prevalence areas, such as South-East Asia. The presence of these viral markers in the circulation suggests that a minimal level of virus reactivation may have occurred in an infected individual, although the underlying mechanism of reactivation remains to be elucidated. Here, we showed that treatment with nocodazole, which provokes the depolymerization of microtubules, induces the expression of two EBV lytic cycle proteins, Zta and EA-D, in EBV-positive NPC cells. This effect was independent of mitotic arrest, as viral reactivation was not abolished in cells synchronized at interphase. Notably, the induction of Zta by nocodazole was mediated by transcriptional upregulation via protein kinase C (PKC). Pre-treatment with inhibitors for PKC or its downstream signalling partners p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) abolished the nocodazole-mediated induction of Zta and EA-D. Interestingly, the effect of nocodazole, as well as colchicine and vinblastine, on lytic gene expression occurred only in NPC epithelial cells but not in cells derived from lymphocytes. These results establish a novel role of microtubule integrity in controlling the EBV life cycle through PKC and its downstream pathways, which represents a tissue-specific mechanism for controlling the life-cycle switch of EBV.

Over-production of nitric oxide by oxidative stress-induced activation of the TGF-β1/PI3K/Akt pathway in mesangial cells cultured in high glucose

AIM

To investigate whether NO over-production in rat mesangial cells cultured in high glucose (HG) is related to activation of the TGF-β1/PI3K/Akt pathway.

METHODS

Rat mesangial cells line (HBZY-1) was exposed to HG (24.44 mmol/L) or H2O2 (10 μmol/L) for 16 h. NO release was quantified using the Griess assay. The TGF-β1 level was measured using ELISA. The protein expression of p-Akt, t-Akt, Bim, and iNOS was examined by Western blotting. The mRNA levels of TGF-β1 and Bim were measured using RT-PCR. The cell proliferation rate was estimated using a BrdU incorporation assay.

RESULTS

Treatment of the cells with HG, H2O2, or TGF-β1 (5 ng/mL) significantly increased the NO level that was substantially inhibited by co-treatment with the NADPH oxidase inhibitor diphenylene iodonium (DPI), TGF-β1 inhibitor SB431542, or PI3K inhibitor LY294002. Both HG and H2O2 significantly increased the protein and mRNA levels of TGF-β1 in the cells, and HG-induced increases of TGF-β1 protein and mRNA were blocked by co-treatment with DPI. Furthermore, the treatment with HG or H2O2 significantly increased the expression of phosphorylated Akt and iNOS and cell proliferation rate, which was blocked by co-treatment with DPI, SB431542, or LY294002. Moreover, the treatment with HG or H2O2 significantly inhibited Bim protein and mRNA expression, which was reversed by co-treatment with DPI, SB431542, or LY294002.

CONCLUSION

The results demonstrate that high glucose causes oxidative stress and NO over-production in rat mesangial cells in vitro via decreasing Bim and increasing iNOS, which are at least partially mediated by the TGF-β1/PI3K/Akt pathway.

Protein kinase inhibitors that inhibit induction of lytic program and replication of Epstein-Barr virus

Signaling pathways mediating Epstein-Barr virus (EBV) reactivation by Ag-bound B-cell receptor (BCR) were analyzed using a panel of 80 protein kinase inhibitors. Broad range protein kinase inhibitors Staurosporine, K252A, and PKC-412 significantly reduced the EBV genome copy numbers measured 48 h after reactivation perhaps due to their higher toxicity. In addition, selected inhibitors of the phosphatidylinositol-3-kinase (PI3K), protein kinase C (PKC), mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB) pathways, glycogen synthase kinase 3β (GSK-3β), platelet-derived growth factor receptor-associated tyrosine kinase (PDGFRK), and epidermal growth factor receptor-associated tyrosine kinase (EGFRK) significantly reduced the EBV genome copy numbers. Of those, only U0126 and Erbstatin analog, which inhibit MAPK pathway and EGFRK, respectively, did not inhibit viral reactivation assessed by expression of the EBV early protein, EA-D. None of the tested compounds, except for K252A, affected the activity of the EBV-encoded protein kinase in vitro. These results show that EBV reactivation induced by BCR signaling is mainly mediated through PI3K and PKC, whereas MAPK might be involved in later stages of viral replication.