Tubulosine selectively inhibits JAK3 signalling by binding to the ATP-binding site of the kinase of JAK3.

Gain- or loss-of-function mutations in Janus kinase 3 (JAK3) contribute to the pathogenesis of various haematopoietic malignancies and immune disorders, suggesting that aberrant JAK3 signalling is an attractive therapeutic target to treat these disorders. In this study, we performed structure-based computational database screening using the 3D structure of the JAK3 kinase domain and the National Cancer Institute diversity set and identified tubulosine as a novel JAK3 inhibitor. Tubulosine directly blocked the catalytic activity of JAK3 by selective interacting with the JAK3 kinase domain. Consistently, tubulosine potently inhibited persistently activated and interleukin-2-dependent JAK3, and JAK3-mediated downstream targets. Importantly, it did not affect the activity of other JAK family members, particularly prolactin-induced JAK2/signal transducer and activator of transcription 5 and interferon alpha-induced JAK1-TYK2/STAT1. Tubulosine specifically decreased survival and proliferation of cancer cells, in which persistently active JAK3 is expressed, by inducing apoptotic and necrotic/autophagic cell death without affecting other oncogenic signalling. Collectively, tubulosine is a potential small-molecule compound that selectively inhibits JAK3 activity, suggesting that it may serve as a promising therapeutic candidate for treating disorders caused by aberrant activation of JAK3 signalling.

Anticancer Activity of Tubulosine through Suppression of Interleukin-6-Induced Janus Kinase 2/Signal Transducer and Activation of Transcription 3 Signaling.

PURPOSE: The chemical structure of tubulosine has been known since the mid-1960s. However, little is known about its biological and pharmacological functions. The aim of this study was to investigate the novel functions of tubulosine in cancer treatment, specifically in breast cancer. METHODS: An Unpaired (Upd)-induced Drosophila cell line and interleukin (IL)-6-stimulated human breast cancer cell lines were used to investigate the biological and pharmacological activities of tubulosine in vitro. To investigate the activities of tubulosine, we performed molecular and cellular experiments such as Western blot and reverse transcription polymerase chain reaction analyses, immunoprecipitation and terminal deoxynucleotidyl transferase dUTP nick end labeling assays, and immunofluorescence staining using breast cancer cell lines. RESULTS: Tubulosine exhibited anticancer activity in IL-6-stimulated human breast cancer cells. Moreover, tubulosine reduced the tyrosine phosphorylation level and transcriptional activity of signal transducer and activator of transcription (STAT) protein at 92E in Upd-induced Drosophila cells. Additionally, tubulosine suppressed IL-6-induced Janus kinase 2 (JAK2)/STAT3 signaling, resulting in decreased viability and induction of apoptotic cell death in breast cancer cells. Interestingly, inhibition of IL-6-induced JAK2/STAT3 signaling by tubulosine was associated with the blocking of IL-6 receptor (IL-6R) and glycoprotein 130 (gp130) binding. CONCLUSION: Tubulosine exhibits anticancer activity through functional inhibition of IL-6-induced JAK2/STAT3 signaling by targeting IL-6Rα/gp130 binding in breast cancer cells. These findings suggest that tubulosine may hold promise for the treatment of inflammation-associated cancers, including breast cancer.

Anti-cancer effect of doxorubicin is mediated by downregulation of HMG-Co A reductase via inhibition of EGFR/Src pathway.

Doxorubicin is a widely used DNA damage-inducing anti-cancer drug. However, its use is limited by its dose-dependent side effects, such as cardiac toxicity. Cholesterol-lowering statin drugs increase the efficacy of some anti-cancer drugs. Cholesterol is important for cell growth and a critical component of lipid rafts, which are plasma membrane microdomains important for cell signaling. 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (HMG-CR) is a critical enzyme in cholesterol synthesis. Here, we show that doxorubicin downregulated HMG-CR protein levels and thus reduced levels of cholesterol and lipid rafts. Cholesterol addition attenuated doxorubicin-induced cell death, and cholesterol depletion enhanced it. Reduction of HMG-CR activity by simvastatin, a statin that acts as an HMG-CR inhibitor, or by siRNA-mediated HMG-CR knockdown enhanced doxorubicin cytotoxicity. Doxorubicin-induced HMG-CR downregulation was associated with inactivation of the EGFR-Src pathway. Furthermore, a high-cholesterol-diet attenuated the anti-cancer activity of doxorubicin in a tumor xenograft mouse model. In a multivulva model of Caenorhabditis elegans expressing an active-EGFR mutant, doxorubicin decreased hyperplasia more efficiently in the absence than in the presence of cholesterol. These data indicate that EGFR/Src/HMG-CR is a new pathway mediating doxorubicin-induced cell death and that cholesterol control could be combined with doxorubicin treatment to enhance efficacy and thus reduce side effects.

Dysfunction of Microglial STAT3 Alleviates Depressive Behavior via Neuron-Microglia Interactions.

Neuron-microglia interactions have a crucial role in maintaining the neuroimmune system. The balance of neuroimmune system has emerged as an important process in the pathophysiology of depression. However, how neuron-microglia interactions contribute to major depressive disorders has been poorly understood. Herein, we demonstrated that microglia-derived synaptic changes induced antidepressive-like behavior by using microglia-specific signal transducer and activator of transcription 3 (STAT3) knockout (KO) (STAT3fl/fl;LysM-Cre+/-) mice. We found that microglia-specific STAT3 KO mice showed antidepressive-like behavior in the forced swim, tail suspension, sucrose preference, and open-field tests. Surprisingly, the secretion of macrophage colony-stimulating factor (M-CSF) was increased from neuronal cells in the brains of STAT3fl/fl;LysM-Cre+/- mice. Moreover, the phosphorylation of antidepressant-targeting mediators and brain-derived neurotrophic factor expression were increased in the brains of STAT3fl/fl;LysM-Cre+/- mice as well as in neuronal cells in response to M-CSF stimulation. Importantly, the miniature excitatory postsynaptic current frequency in the medial prefrontal cortex was increased in STAT3fl/fl;LysM-Cre+/- mice and in the M-CSF treatment group. Collectively, microglial STAT3 regulates depression-related behaviors via neuronal M-CSF-mediated synaptic activity, suggesting that inhibition of microglial STAT3 might be a new therapeutic strategy for depression.

STAT3 Potentiates SIAH-1 Mediated Proteasomal Degradation of ß-Catenin in Human Embryonic Kidney Cells.

The ß-catenin functions as an adhesion molecule and a component of the Wnt signaling pathway. In the absence of the Wnt ligand, ß-catenin is constantly phosphorylated, which designates it for degradation by the APC complex. This process is one of the key regulatory mechanisms of ß-catenin. The level of ß-catenin is also controlled by the E3 ubiquitin protein ligase SIAH-1 via a phosphorylation-independent degradation pathway. Similar to ß-catenin, STAT3 is responsible for various cellular processes, such as survival, proliferation, and differentiation. However, little is known about how these molecules work together to regulate diverse cellular processes. In this study, we investigated the regulatory relationship between STAT3 and ß-catenin in HEK293T cells. To our knowledge, this is the first study to report that ß-catenin-TCF-4 transcriptional activity was suppressed by phosphorylated STAT3; furthermore, STAT3 inactivation abolished this effect and elevated activated ß-catenin levels. STAT3 also showed a strong interaction with SIAH-1, a regulator of active ß-catenin via degradation, which stabilized SIAH-1 and increased its interaction with ß-catenin. These results suggest that activated STAT3 regulates active ß-catenin protein levels via stabilization of SIAH-1 and the subsequent ubiquitin-dependent proteasomal degradation of ß-catenin in HEK293T cells.

Signal transducer and activator of transcription 3 as a therapeutic target for cancer and the tumor microenvironment.

Signal transducer and activator of transcription 3 (STAT3) is a cytoplasmic transcription factor that modulates the transcription of a variety of genes to regulate important biological functions, including cell proliferation, differentiation, survival, angiogenesis, and immune response. Constitutive activation of STAT3 is important in oncogenic signaling and occurs at high frequency in human cancers, including diverse solid tumors and hematologic malignancies. Moreover, it is associated with a poor prognosis. The tumor microenvironment has recently been recognized as a key condition for cancer progression, invasion, angiogenesis, metastasis, and drug resistance by activation of STAT3 signaling. Therefore, understanding the biology associated with STAT3-mediated signaling cascades in the tumor microenvironment may offer the therapeutic potential to treat human cancers. This review presents an overview of the critical roles of STAT3 in the tumor microenvironment related to cancer biology and discusses recent advancements in the development of anticancer drugs that therapeutically inhibit STAT3 signaling cascades.

Ginsenoside 20(S)-Rh2 exerts anti-cancer activity through targeting IL-6-induced JAK2/STAT3 pathway in human colorectal cancer cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Panax ginseng is one of the most well-known medicinal herbs in Korea and China, which has been used for treatment and prevention of cancer, obesity, diabetes, and cardiovascular diseases. Ginsenosides are the major components of P. ginseng, having a wide range of pharmacological activities. Among the ginsenosides, protopanaxadiol (PPD)-types reportedly have potent anti-cancer effects. Rh2 is PPD-type ginsenoside, and two stereoisomeric forms of Rh2 as 20(S)- and 20(R)-Rh2 were selectively isolated recently. AIM OF THE STUDY: The biological activities of Rh2 ginsenosides are known to depend on their differences in stereochemistry. Colorectal cancer (CRC) is one of the most lethal neoplasm, and cancer-related death is usually associated with metastasis to other organs. We aimed this study to investigate whether 20(S)- and 20(R)-Rh2 can suppress tumor invasion in human CRC cells. MATERIALS AND METHODS: 20(S)- and 20(R)-Rh2 were isolated from the roots of ginseng. Human CRC cells were incubated with 20(S)- or 20(R)-Rh2 in the presence or absence of interleukin-6. An MTT assay was used to measure cell viability. Western blot and quantitative real-time PCR analyses were performed to determine levels of expression and phosphorylation. An invasion assay was performed using a Boyden chamber system with the Matrigel-coated membrane to measure cancer cell invasion. RESULTS: 20(S)- and 20(R)-Rh2 showed differential cytotoxic activity. Only 20(S)-Rh2 decreased cancer cell viability. Additionally, 20(S)-Rh2 effectively inhibited IL-6-induced signal transducer and activator of transcription 3 (STAT3) phosphorylation and the expression of matrix metalloproteinases (MMPs), including MMP-1, -2, and -9, resulting in inhibition of cancer cell invasion. Interestingly, these pharmacological activities of 20(S)-Rh2 were more potent than those of 20(R)-Rh2. Furthermore, combination treatment showed that 20(S)-Rh2 enhanced the sensitization of doxorubicin-treated anti-cancer activities in CRC cells. CONCLUSION: Our results demonstrated that ginsenoside 20(S)-Rh2 has therapeutic potential for the treatment with CRC and may be valuable as a combination partner with more classic chemotherapeutic agents, such as doxorubicin, to treat CRC.

Alleviation of collagen-induced arthritis by the benzoxathiole derivative BOT-4-one in mice: Implication of the Th1- and Th17-cell-mediated immune responses.

Autoimmune rheumatoid arthritis is characterized by chronic inflammation and hyperplasia in the synovial joints. Although the cause of rheumatoid arthritis is largely unknown, substantial evidence has supported the importance of immune cells and inflammatory cytokines in the initiation and progression of this disease. Herein, we demonstrated that the benzoxathiole derivative 2-cyclohexylimino-6-methyl-6,7-dihydro-5H-benzo[1,3]oxathiol-4-one (BOT-4-one) alleviated type II collagen-induced arthritis in a mouse model. The levels of pro-inflammatory cytokines are elevated in both human patients with rheumatoid arthritis and mice with collagen-induced arthritis. BOT-4-one treatment reduced the levels of pro-inflammatory cytokines in mice and endotoxin-stimulated macrophages. BOT-4-one treatment suppressed the polarization of Th1- and Th17-cell subsets by inhibiting the expression and production of their lineage-specific master transcription factors and cytokines, as well as activation of signal transducer and activator of transcription proteins. In addition, BOT-4-one inhibited mitogen-activated protein kinase and NF-kappaB signaling as well as the transcriptional activities and DNA-binding of transcription factors, including activator protein-1, cAMP response element-binding protein and NF-kappaB. Our results suggest that BOT-4-one may have therapeutic potential for the treatment of chronic inflammation associated with autoimmune rheumatoid arthritis.

Photoprotective Potential of Penta-O-Galloyl-ß-DGlucose by Targeting NF-κB and MAPK Signaling in UVB Radiation-Induced Human Dermal Fibroblasts and Mouse Skin.

Exposure of the skin to ultraviolet radiation can cause skin damage with various pathological changes including inflammation. In the present study, we identified the skin-protective activity of 1,2,3,4,6-penta-O-galloyl-ß-D-glucose (pentagalloyl glucose, PGG) in ultraviolet B (UVB) radiation-induced human dermal fibroblasts and mouse skin. PGG exhibited antioxidant activity with regard to intracellular reactive oxygen species (ROS) generation as well as ROS and reactive nitrogen species (RNS) scavenging. Furthermore, PGG exhibited anti-inflammatory activity, inhibiting the activation of nuclear factor-kappaB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling, resulting in inhibition of the expression of pro-inflammatory mediators. Topical application of PGG followed by chronic exposure to UVB radiation in the dorsal skin of hairless mice resulted in a significant decrease in the progression of inflammatory skin damages, leading to inhibited activation of NF-κB signaling and expression of pro-inflammatory mediators. The present study demonstrated that PGG protected from skin damage induced by UVB radiation, and thus, may be a potential candidate for the prevention of environmental stimuli-induced inflammatory skin damage.

Signal transducer and activator of transcription 3-mediated CD133 up-regulation contributes to promotion of hepatocellular carcinoma.

UNLABELLED: Enhanced expression of the cancer stem cell (CSC) marker, CD133, is closely associated with a higher rate of tumor formation and poor prognosis in hepatocellular carcinoma (HCC) patients. Despite its clinical significance, the molecular mechanism underlying the deregulation of CD133 during tumor progression remains to be clarified. Here, we report on a novel mechanism by which interleukin-6/signal transducer and activator of transcription 3 (IL-6/STAT3) signaling up-regulates expression of CD133 and promotes HCC progression. STAT3 activated by IL-6 rapidly bound to CD133 promoter and increased protein levels of CD133 in HCC cells. Reversely, in hypoxic conditions, RNA interference silencing of STAT3 resulted in decrease of CD133 levels, even in the presence of IL-6, with a concomitant decrease of hypoxia-inducible factor 1 alpha (HIF-1α) expression. Active STAT3 interacted with nuclear factor kappa B (NF-κB) p65 subunit to positively regulate the transcription of HIF-1α providing a mechanistic explanation on how those three oncogenes work together to increase the activity of CD133 in a hypoxic liver microenvironment. Activation of STAT3 and its consequent induction of HIF-1α and CD133 expression were not observed in Toll-like receptor 4/IL-6 double-knockout mice. Long-term silencing of CD133 by a lentiviral-based approach inhibited cancer cell-cycle progression and suppressed in vivo tumorigenicity by down-regulating expression of cytokinesis-related genes, such as TACC1, ACF7, and CKAP5. We also found that sorafenib and STAT3 inhibitor nifuroxazide inhibit HCC xenograft formation by blocking activation of STAT3 and expression of CD133 and HIF-1α proteins. CONCLUSION: IL-6/STAT3 signaling induces expression of CD133 through functional cooperation with NF-κB and HIF-1α during liver carcinogenesis. Targeting STAT3-mediated CD133 up-regulation may represent a novel, effective treatment by eradicating the liver tumor microenvironment.

Signal transducer and activator of transcription 3 (Stat3) contributes to T-cell homeostasis by regulating pro-survival Bcl-2 family genes.

The naive T-cell pool in peripheral lymphoid tissues is fairly stable in terms of number, diversity and functional capabilities in spite of the absence of prominent stimuli. This stability is attributed to continuous tuning of the composition of the T-cell pool by various homeostatic signals. Despite extensive research into the link between signal transducer and activator of transcription 3 (Stat3) and T-cell survival, little is known about how Stat3 regulates homeostasis by maintaining the required naive T-cell population in peripheral lymphoid organs. We assessed whether the elimination of Stat3 in T cells limits T-cell survival. We demonstrated that the proportion and number of single-positive thymocytes as well as T cells in the spleen and lymph nodes were significantly decreased in the Stat3-deficient group as a result of the enhanced susceptibility of Stat3-deleted T lymphocytes to apoptosis. Importantly, expression of the anti-apoptotic Bcl-2 and Bcl-xL was markedly decreased in Stat3-deleted single-positive thymocytes and T lymphocytes, suggesting that Stat3 helps to maintain the T-cell pool in the resting condition by promoting the expression of Bcl-2 family genes. These findings suggest the importance of Stat3 in the integration of homeostatic cues for the maintenance and functional tuning of the T-cell pool.

Relative antioxidant activities of quercetin and its structurally related substances and their effects on NF-κB/CRE/AP-1 signaling in murine macrophages.

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) produced by the oxidative burst in activated macrophages and neutrophils cause oxidative stressimplicated diseases. Quercetin is flavonoid that occurs naturally in plants and is widely used as a nutritional supplement due to its antioxidant and anti-inflammatory properties. In this study, we investigated antioxidant activities and mechanisms of action in zymosan-induced macrophages of quercetin and quercetin-related flavonoids such as quercitrin, isoquercitrin, quercetin 3-O-ß-(2″-galloyl)-rhamnopyranoside (QGR) and quercetin 3-O-ß-(2″-galloyl)-glucopyranoside (QGG) as well as gallic acid, a building moiety of QGR and QGG. QGR and QGG exhibited stronger antioxidant activities compared with quercetin, whereas quercitrin, isoquercitrin and gallic acid exhibited weak-tono antioxidant activities, assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, superoxide production, superoxide scavenging, nitric oxide (NO) production, peroxynitrite (ONOO(-)) scavenging and myeloperoxidase (MPO) activity. Regarding mechanisms, the quercetincontaining flavonoids QGR and QGG differentially targeted compared with quercetin in the NF-κB signaling pathway that inhibited the DNA binding activity of the NF-κB complex without affecting the degradation and phosphorylation of IκBα and NF-κB phosphorylation. In addition, QGR and QGG inhibited CRE and activator protein (AP-1) transcriptional activity and JNK phosphorylation by inhibiting the cAMP/protein kinase A (PKA) and protein kinase C (PKC) signaling in a different manner than quercetin. Our results showed that although QGR and QGG exhibited stronger antioxidant activities than querce-tin in macrophages, their mechanisms of action in terms of the NF-κB, PKA and PKC signaling pathways were different.

BST-2 is a potential activator of invasion and migration in tamoxifen-resistant breast cancer cells.

Bone marrow stromal cell antigen 2 (BST-2) is a type II transmembrane protein that is known to be a therapeutic target in several types of cancer. However, despite its clinical importance, the roles of BST-2 expression have remained elusive. Here, we found that BST-2 expression is up-regulated in tamoxifen-resistant MCF-7 human breast cancer (TRM-7) cells, resulting in enhanced invasiveness and migration. Matrigel and wound healing assays also showed that overexpression of BST-2 increased invasion and migration in MCF-7 cells, whereas invasion and migration were decreased by the silencing of BST-2 in TRM-7 cells. In addition, B16F10 cells expressing BST-2 showed increased metastatic melanoma nodule growth in a lung metastasis mouse model. Furthermore, BST-2 expression and promoter activity were regulated by activated signal transducer and activator of transcription 3 (STAT3). Taken together, our results indicate that BST-2 is an important factor in the invasiveness and motility of tamoxifen-resistant breast cancer cells, and that its expression and activity are regulated by activated STAT3. Therefore, regulation of BST-2 is a potential therapeutic target for tamoxifen-resistant breast cancer.

Simvastatin suppresses RANTES-mediated neutrophilia in polyinosinic-polycytidylic acid-induced pneumonia.

Recently, statins have been shown to have anti-inflammatory effects on lung inflammatory diseases. However, the mechanisms of action of simvastatin in viral pneumonia have yet to be elucidated, although viral infection remains a considerable health threat. In this study, we hypothesised that simvastatin inhibits polyinosinic-polycytidylic acid (poly I:C)-induced airway inflammation, such as RANTES (regulated on activation, normal T-cell expressed and secreted) expression and inflammatory cell recruitment. In bronchial cells, the effect of simvastatin on poly I:C-induced RANTES expression and signal transducer and activator of transcription (STAT)3-mediated signal transduction was determined using an ELISA and short hairpin (sh)RNA system. In a poly I:C-induced pneumonia mouse model, immunological changes in the lungs after simvastatin inhalation, such as inflammatory cell recruitment and cytokine/chemokine release, were examined. In poly I:C-stimulated bronchial cells, RANTES secretion was increased by STAT3 activation, and simvastatin suppressed poly I:C-induced STAT3 activation, resulting in inhibition of RANTES expression. In BALB/c mice stimulated with inhaled poly I:C, RANTES expression and neutrophil infiltration into the airway were elevated. However, simvastatin treatment attenuated STAT3 activation, RANTES release and subsequent neutrophilia in the lungs. These findings suggest that simvastatin inhibits airway inflammation, but there are other mechanisms that need to be fully elucidated.

STAT3-RANTES autocrine signaling is essential for tamoxifen resistance in human breast cancer cells.

The acquisition of tamoxifen resistance is a major therapeutic problem in breast cancer. We developed a tamoxifen-resistant MCF-7 (TRM-7) cell line to elucidate the molecular mechanisms and factors associated with acquisition of such resistance. We showed that phosphorylation of STAT3 at tyrosine 705 (Y705) and RANTES expression are increased in response to tamoxifen in human breast cancer cells. On the basis of these results, we hypothesize that upregulated STAT3 phosphorylation and RANTES may be correlated with the development of drug resistance. Here, we showed that STAT3 and RANTES contribute to the maintenance of drug resistance. STAT3 phosphorylation is constitutively retained via a RANTES autocrine loop, which in turn upregulates anti-apoptotic signals in TRM-7 cells. STAT3-RANTES autocrine signaling affected expression of anti-apoptotic BCL-2 family genes and prevented TRM-7 cells from undergoing programmed cell death by inhibiting PARP and caspase-9 cleavage. Subsequently, blockade of STAT3 and RANTES in TRM-7 cells resulted in reduction of anti-apoptotic signals, which was rescued by exogenous RANTES treatment; drug resistance was also restored. Taken together, our results suggested that STAT3-RANTES autocrine signaling is essential for maintenance of drug resistance and inhibition of programmed cell death. These mechanisms of STAT3-RANTES autocrine signaling suggest a novel strategy for management of patients with tamoxifen-resistant tumors.

CK20 expression enhances the invasiveness of tamoxifen-resistant MCF-7 cells.

Cytokeratin 20 (CK20) is an intermediate filament that is known to be a prognostic marker in several types of cancer. However, little is known about CK20 expression and tumor metastasis in tamoxifen-resistant MCF-7 (TRM-7) breast cancer cells. TRM-7 cells overexpress CK20, resulting in enhanced invasiveness in vitro. CK20 silencing reduced the invasiveness of TRM-7 cells. Moreover, CK20 expression in MCF-7 cells was regulated by peroxisome proliferator-activated receptor γ (PPARγ). Our findings suggest that PPARγ-dependent CK20 expression enhances the metastatic potential of MCF-7 breast cancer cells and may be a potential therapeutic target in tamoxifen-resistant breast cancer.

Anti-dermatitis effects of oak wood vinegar on the DNCB-induced contact hypersensitivity via STAT3 suppression.

AIMS OF THE STUDY: The aim of this study was to evaluate the anti-dermatitis effects of oak wood vinegar (OWV) in a 2,4-dinitrochlorobenzene (DNCB)-induced contact dermatitis mice model. MATERIALS AND METHODS: Immunoglobulin E (IgE) production, infiltration of immune cells (neutrophils, CD3+ cells), inducible nitric oxide synthase (iNOS) expression, skin thickness, and expression of phosphorylated STAT3 (signal transducers and activators of transcription 3) protein were tested in a DNCB-induced contact dermatitis model. In vitro wound healing and proliferative assays were also performed. RESULTS: OWV showed anti-inflammatory effects on DNCB-induced dermatitis in mice, leading to inhibition of IgE production, immune cell infiltration, and iNOS expression. Skin thickness and the level of phospho-STAT3 were dramatically reduced by OWV. Using the HaCaT human keratinocyte cell line, we confirmed that constitutive STAT3 activation induced faster proliferation of epithelial cells. In addition, OWV suppressed HaCaT proliferative ability and phospho-STAT3 levels. CONCLUSIONS: The study revealed that OWV has anti-inflammatory and anti-proliferative effects in a DNCB-induced contact dermatitis mice model. Furthermore, we showed that the mechanism by which OWV most likely inhibits epithelial proliferation is through STAT3 inactivation.

Inhibition of double-stranded RNA-induced inducible nitric oxide synthase expression by fraxinellone and sauchinone in murine microglia.

Fraxinellone and sauchinone, isolated from natural substance, are known to have an anti-inflammatory effect in inflammatory conditions. However, the anti-inflammatory actions of these compounds have been insufficiently demonstrated in viral-induced neuroinflammation. A viral component (double-stranded (ds)RNA) triggers a toll-like receptor 3-dependent inflammatory response that stimulates pro-inflammatory mediators in the brain. In present study, we initially examined the biological effects of fraxinellone and sauchinone on anti-inflammatory actions in dsRNA-stimulated microglia. Both compounds inhibited dsRNA-induced inducible nitric oxide synthase (iNOS) expression, a major pro-inflammatory enzyme. To demonstrate the mechanism of inhibitory effect on iNOS expression, we further examined the signaling pathway induced by dsRNA in microglia. Our data show that dsRNA promotes the expression of signal transducers and activators of transcription (STAT)1/3 identified as major inflammatory transcription factors as well as activates c-Jun N-terminal kinase (JNK) in an early time. Moreover, both compounds suppressed activation of JNK-STAT1/3 signaling pathway. These results suggest that an anti-inflammatory effect by fraxinellone and sauchinone is mediated via blockade of the JNK-STAT1/3-iNOS signaling pathway in viral-infected microglia.