Sample records for ebna2 regulates stat3

  1. Differential regulation of miR-21 and miR-146a by Epstein–Barr virus-encoded EBNA2

    PubMed Central

    Rosato, P; Anastasiadou, E; Garg, N; Lenze, D; Boccellato, F; Vincenti, S; Severa, M; Coccia, E M; Bigi, R; Cirone, M; Ferretti, E; Campese, A F; Hummel, M; Frati, L; Presutti, C; Faggioni, A; Trivedi, P

    2012-01-01

    The discovery of microRNA (miR) represents a novel paradigm in RNA-based regulation of gene expression and their dysregulation has become a hallmark of many a tumor. In virally associated cancers, the host–pathogen interaction could involve alteration in miR expression. Epstein–Barr virus (EBV)-encoded EBNA2 is indispensable for the capacity of the virus to transform B cells in vitro. Here, we studied how it affects cellular miRs. Extensive miR profiling of the virus-infected and EBNA2-transfected B lymphoma cells revealed that oncomiR miR-21 is positively regulated by this viral protein. Conversely, Burkitt's lymphoma (BL) cell lines infected with EBNA2 lacking P3HR1 strain did not show any increase in miR-21. EBNA2 increased phosphorylation of AKT and this was directly correlated with increased miR-21. In contrast, miR-146a was downregulated by EBNA2 in B lymphoma cells. Low miR-146a expression correlates with an elevated level of IRAK1 and type I interferon in EBNA2 transfectants. Taken together, the present data suggest that EBNA2 might contribute to EBV-induced B-cell transformation by altering miR expression and in particular by increasing oncomiR-like miR-21 and by affecting the antiviral responses of the innate immune system through downregulation of its key regulator miR-146a. PMID:22614176

  2. Differential regulation of miR-21 and miR-146a by Epstein-Barr virus-encoded EBNA2.

    PubMed

    Rosato, P; Anastasiadou, E; Garg, N; Lenze, D; Boccellato, F; Vincenti, S; Severa, M; Coccia, E M; Bigi, R; Cirone, M; Ferretti, E; Campese, A F; Hummel, M; Frati, L; Presutti, C; Faggioni, A; Trivedi, P

    2012-11-01

    The discovery of microRNA (miR) represents a novel paradigm in RNA-based regulation of gene expression and their dysregulation has become a hallmark of many a tumor. In virally associated cancers, the host-pathogen interaction could involve alteration in miR expression. Epstein-Barr virus (EBV)-encoded EBNA2 is indispensable for the capacity of the virus to transform B cells in vitro. Here, we studied how it affects cellular miRs. Extensive miR profiling of the virus-infected and EBNA2-transfected B lymphoma cells revealed that oncomiR miR-21 is positively regulated by this viral protein. Conversely, Burkitt's lymphoma (BL) cell lines infected with EBNA2 lacking P3HR1 strain did not show any increase in miR-21. EBNA2 increased phosphorylation of AKT and this was directly correlated with increased miR-21. In contrast, miR-146a was downregulated by EBNA2 in B lymphoma cells. Low miR-146a expression correlates with an elevated level of IRAK1 and type I interferon in EBNA2 transfectants. Taken together, the present data suggest that EBNA2 might contribute to EBV-induced B-cell transformation by altering miR expression and in particular by increasing oncomiR-like miR-21 and by affecting the antiviral responses of the innate immune system through downregulation of its key regulator miR-146a. PMID:22614176

  3. A Single Amino Acid in EBNA-2 Determines Superior B Lymphoblastoid Cell Line Growth Maintenance by Epstein-Barr Virus Type 1 EBNA-2

    PubMed Central

    Tzellos, Stelios; Correia, Paulo B.; Karstegl, Claudio Elgueta; Cancian, Laila; Cano-Flanagan, Julian; McClellan, Michael J.; West, Michelle J.

    2014-01-01

    ABSTRACT Sequence differences in the EBNA-2 protein mediate the superior ability of type 1 Epstein-Barr virus (EBV) to transform human B cells into lymphoblastoid cell lines compared to that of type 2 EBV. Here we show that changing a single amino acid (S442D) from serine in type 2 EBNA-2 to the aspartate found in type 1 EBNA-2 confers a type 1 growth phenotype in a lymphoblastoid cell line growth maintenance assay. This amino acid lies in the transactivation domain of EBNA-2, and the S442D change increases activity in a transactivation domain assay. The superior growth properties of type 1 EBNA-2 correlate with the greater induction of EBV LMP-1 and about 10 cell genes, including CXCR7. In chromatin immunoprecipitation assays, type 1 EBNA-2 is shown to associate more strongly with EBNA-2 binding sites near the LMP-1 and CXCR7 genes. Unbiased motif searching of the EBNA-2 binding regions of the differentially regulated cell genes identified an ETS-interferon regulatory factor composite element motif that closely corresponds to the sequences known to mediate EBNA-2 regulation of the LMP-1 promoter. It appears that the superior induction by type 1 EBNA-2 of the cell genes contributing to cell growth is due to their being regulated in a manner different from that for most EBNA-2-responsive genes and in a way similar to that for the LMP-1 gene. IMPORTANCE The EBNA-2 transcription factor plays a key role in B cell transformation by EBV and defines the two EBV types. Here we identify a single amino acid (Ser in type 1 EBV, Asp in type 2 EBV) of EBNA-2 that determines the superior ability of type 1 EBNA-2 to induce a key group of cell genes and the EBV LMP-1 gene, which mediate the growth advantage of B cells infected with type 1 EBV. The EBNA-2 binding sites in these cell genes have a sequence motif similar to the sequence known to mediate regulation of the EBV LMP-1 promoter. Further detailed analysis of transactivation and promoter binding provides new insight into the physiological regulation of cell genes by EBNA-2. PMID:24850736

  4. STAT3 Regulation by S-Nitrosylation: Implication for Inflammatory Disease

    PubMed Central

    Kim, Jinsu; Won, Je-Seong; Singh, Avtar K.; Sharma, Anand K.

    2014-01-01

    Abstract Aims: S-nitrosylation and S-glutathionylation, redox-based modifications of protein thiols, are recently emerging as important signaling mechanisms. In this study, we assessed S-nitrosylation-based regulation of Janus-activated kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway that plays critical roles in immune/inflammatory responses and tumorigenesis. Results: Our studies show that STAT3 in stimulated microglia underwent two distinct redox-dependent modifications, S-nitrosylation and S-glutathionylation. STAT3 S-nitrosylation was associated with inducible nitric oxide synthase (iNOS)-produced nitric oxide (NO) and S-nitrosoglutathione (GSNO), whereas S-glutathionylation of STAT3 was associated with cellular oxidative stress. NO produced by iNOS or treatment of microglia with exogenous GSNO inhibited STAT3 activation via inhibiting STAT3 phosphorylation (Tyr705). Consequently, the interleukin-6 (IL-6)-induced microglial proliferation and associated gene expressions were also reduced. In cell-free kinase assay using purified JAK2 and STAT3, STAT3 phosphorylation was inhibited by its selective preincubation with GSNO, but not by preincubation of JAK2 with GSNO, indicating that GSNO-mediated mechanisms inhibit STAT3 phosphorylation through S-nitrosylation of STAT3 rather than JAK2. In this study, we identified that Cys259 was the target Cys residue of GSNO-mediated S-nitrosylation of STAT3. The replacement of Cys259 residue with Ala abolished the inhibitory role of GSNO in IL-6-induced STAT3 phosphorylation and transactivation, suggesting the role of Cys259 S-nitrosylation in STAT3 phosphorylation. Innovation: Microglial proliferation is regulated by NO via S-nitrosylation of STAT3 (Cys259) and inhibition of STAT3 (Tyr705) phosphorylation. Conclusion: Our results indicate the regulation of STAT3 by NO-based post-translational modification (S-nitrosylation). These findings have important implications for the development of new therapeutics targeting STAT3 for treating diseases associated with inflammatory/immune responses and abnormal cell proliferation, including cancer. Antioxid. Redox Signal. 20, 2514–2527. PMID:24063605

  5. Early Activation of STAT3 Regulates Reactive Astrogliosis Induced by Diverse Forms of Neurotoxicity

    PubMed Central

    O'Callaghan, James P.; Kelly, Kimberly A.; VanGilder, Reyna L.; Sofroniew, Michael V.; Miller, Diane B.

    2014-01-01

    Astrogliosis, a cellular response characterized by astrocytic hypertrophy and accumulation of GFAP, is a hallmark of all types of central nervous system (CNS) injuries. Potential signaling mechanisms driving the conversion of astrocytes into “reactive” phenotypes differ with respect to the injury models employed and can be complicated by factors such as disruption of the blood-brain barrier (BBB). As denervation tools, neurotoxicants have the advantage of selective targeting of brain regions and cell types, often with sparing of the BBB. Previously, we found that neuroinflammation and activation of the JAK2-STAT3 pathway in astrocytes precedes up regulation of GFAP in the MPTP mouse model of dopaminergic neurotoxicity. Here we show that multiple mechanistically distinct mouse models of neurotoxicity (MPTP, AMP, METH, MDA, MDMA, KA, TMT) engender the same neuroinflammatory and STAT3 activation responses in specific regions of the brain targeted by each neurotoxicant. The STAT3 effects seen for TMT in the mouse could be generalized to the rat, demonstrating cross-species validity for STAT3 activation. Pharmacological antagonists of the neurotoxic effects blocked neuroinflammatory responses, pSTAT3tyr705 and GFAP induction, indicating that damage to neuronal targets instigated astrogliosis. Selective deletion of STAT3 from astrocytes in STAT3 conditional knockout mice markedly attenuated MPTP-induced astrogliosis. Monitoring STAT3 translocation in GFAP-positive cells indicated that effects of MPTP, METH and KA on pSTAT3tyr705 were localized to astrocytes. These findings strongly implicate the STAT3 pathway in astrocytes as a broadly triggered signaling pathway for astrogliosis. We also observed, however, that the acute neuroinflammatory response to the known inflammogen, LPS, can activate STAT3 in CNS tissue without inducing classical signs of astrogliosis. Thus, acute phase neuroinflammatory responses and neurotoxicity-induced astrogliosis both signal through STAT3 but appear to do so through different modules, perhaps localized to different cell types. PMID:25025494

  6. STAT3 Phosphorylation at Tyrosine 705 and Serine 727 Differentially Regulates Mouse ESC Fates

    PubMed Central

    Huang, Guanyi; Yan, Hexin; Ye, Shoudong; Tong, Chang; Ying, Qi-Long

    2014-01-01

    STAT3 can be transcriptionally activated by phosphorylation of its tyrosine 705 or serine 727 residue. In mouse embryonic stem cells (mESCs), leukemia inhibitory factor (LIF) signaling maintains pluripotency by inducing JAK-mediated phosphorylation of STAT3 Y705 (pY705). However, the function of phosphorylated S727 (pS727) in mESCs remains unclear. In this study, we examined the roles of STAT3 pY705 and pS727 in regulating mESC identities, using a small molecule-based system to post-translationally modulate the quantity of transgenic STAT3 in STAT3?/? mESCs. We demonstrated that pY705 is absolutely required for STAT3-mediated mESC self-renewal, while pS727 is dispensable, serving only to promote proliferation and optimal pluripotency. S727 phosphorylation is regulated directly by fibroblast growth factor/Erk signaling and crucial in the transition of mESCs from pluripotency to neuronal commitment. Loss of S727 phosphorylation resulted in significantly reduced neuronal differentiation potential, which could be recovered by a S727 phosphorylation mimic. Moreover, loss of pS727 sufficed LIF to reprogram epiblast stem cells to naïve pluripotency, suggesting a dynamic equilibrium of STAT3 pY705 and pS727 in the control of mESC fate. PMID:24302476

  7. STAT3-mediated Coincidence Detection Regulates Noncanonical Immediate Early Gene Induction*

    PubMed Central

    Waitkus, Matthew S.; Chandrasekharan, Unni M.; Willard, Belinda; Haque, S. Jaharul; DiCorleto, Paul E.

    2013-01-01

    Signaling pathways interact with one another to form dynamic networks in which the cellular response to one stimulus may depend on the presence, intensity, timing, or localization of other signals. In rare cases, two stimuli may be simultaneously required for cells to elicit a significant biological output. This phenomenon, generally termed “coincidence detection,” requires a downstream signaling node that functions as a Boolean AND gate to restrict biological output from a network unless multiple stimuli are received within a specific window of time. Simultaneous activation of the EGF receptor (EGFR) and a thrombin receptor (protease-activated receptor-1, PAR-1) increases the expression of multiple immediate early genes (IEGs) associated with growth and angiogenesis. Using a bioinformatic comparison of IEG promoter regions, we identified STAT3 as a critical transcription factor for the detection of coincident EGFR/PAR-1 activation. EGFR activation induces classical STAT3 Tyr705 phosphorylation but also initiates an inhibitory signal through the PI3K-AKT signaling axis that prevents STAT3 Ser727 phosphorylation. Coincident PAR-1 signaling resolves these conflicting EGF-activated pathways by blocking AKT activation and permitting GSK-3?/?-dependent STAT3 Ser727 phosphorylation and STAT3-dependent gene expression. Functionally, combinatorial EGFR/PAR-1 signaling suppresses EGF-induced proliferation and thrombin-induced leukocyte adhesion and triggers a STAT3-dependent increase in endothelial cell migration. This study reveals a novel signaling role for STAT3 in which the simultaneous presence of extracellular EGF and thrombin is detected at the level of STAT3 post-translational modifications. Collectively, our results describe a novel regulatory mechanism in which combinatorial EGFR/PAR-1 signaling regulates STAT3-dependent IEG induction and endothelial cell migration. PMID:23504318

  8. STAT3 down regulates LC3 to inhibit autophagy and pancreatic cancer cell growth

    PubMed Central

    Gong, Jingjing; Muñoz, Amanda R.; Chan, Daniel; Ghosh, Rita; Kumar, Addanki P.

    2014-01-01

    The dismal 5-year survival (<5%) for pancreatic cancer (PanCA) underscores the need for developing effective therapeutic options. Recent studies from our laboratory have shown that Nexrutine® (Nx), a bark extract from Phellodendron amurense exhibits excellent anticancer activity in human pancreatic cancer cells through inhibition of inflammatory signaling via STAT3/NF?B/Cox-2. Given the apparent high oxidative stress and autophagic activity in pancreatic tumors, we investigated the potential of Nx to modulate autophagy, reactive oxygen species (ROS), and their crosstalk. Our results show that Nx inhibits autophagy and decreases ROS generation. Pharmacological inhibition of autophagy led to decreased ROS generation and proliferation with no significant effect on apoptosis. Further, using combination index analysis we also found that combination of late-stage autophagy inhibitor with Nx exhibited a moderate synergistic to additive effect. Additionally, genetic or pharmacological inactivation of STAT3 reduced LC3-II levels and expression indicating a possible role for STAT3 in transcriptional regulation of autophagy. Since both inflammatory and oxidative stress signaling activate STAT3, our data implicates that STAT3 plays a vital role in the regulation of autophagy through its contributions to the positive feedback loop between ROS and autophagy. Overall, our findings reveal an important role for STAT3/LC3/ROS in Nx-mediated anti-pancreatic cancer effects. PMID:24796733

  9. STAT3 Regulates Uterine Epithelial Remodeling and Epithelial-Stromal Crosstalk During Implantation

    PubMed Central

    Pawar, Sandeep; Starosvetsky, Elina; Orvis, Grant D.; Behringer, Richard R.; Bagchi, Indrani C.

    2013-01-01

    Embryo implantation is regulated by a variety of endometrial factors, including cytokines, growth factors, and transcription factors. Earlier studies identified the leukemia inhibitory factor (LIF), a cytokine produced by uterine glands, as an essential regulator of implantation. LIF, acting via its cell surface receptor, activates the signal transducer and activator of transcription 3 (STAT3) in the uterine epithelial cells. However, the precise mechanism via which activated STAT3 promotes uterine function during implantation remains unknown. To identify the molecular pathways regulated by STAT3, we created SWd/d mice in which Stat3 gene is conditionally inactivated in uterine epithelium. The SWd/d mice are infertile due to a lack of embryo attachment to the uterine luminal epithelium and consequent implantation failure. Gene expression profiling of uterine epithelial cells of SWd/d mice revealed dysregulated expression of specific components of junctional complexes, including E-cadherin, ?- and ?-catenin, and several claudins, which critically regulate epithelial junctional integrity and embryo attachment. In addition, uteri of SWd/d mice exhibited markedly reduced stromal proliferation and differentiation, indicating that epithelial STAT3 controls stromal function via a paracrine mechanism. The stromal defect arose from a drastic reduction in the production of several members of the epidermal growth factor family in luminal epithelium of SWd/d uteri and the resulting lack of activation of epidermal growth factor receptor signaling and mitotic activity in the stromal cells. Collectively, our results uncovered an intricate molecular network operating downstream of STAT3 that regulates uterine epithelial junctional reorganization, and stromal proliferation, and differentiation, which are critical determinants of successful implantation. PMID:24100212

  10. IL-10 regulates adult neurogenesis by modulating ERK and STAT3 activity

    PubMed Central

    Pereira, Leticia; Font-Nieves, Miriam; Van den Haute, Chris; Baekelandt, Veerle; Planas, Anna M.; Pozas, Esther

    2015-01-01

    The adult subventricular zone (SVZ) contains Nestin+ progenitors that differentiate mainly into neuroblasts. Our previous data showed that interleukin-10 (IL-10) regulates SVZ adult neurogenesis by up-regulating the expression of pro-neural genes and modulating cell cycle exit. Here we addressed the specific mechanism through which IL-10 carries out its signaling on SVZ progenitors. We found that, in vitro and in vivo, IL-10 targets Nestin+ progenitors and activates the phosphorylation of ERK and STAT3. The action of IL-10 on Nestin+ progenitors is reversed by treatment with a MEK/ERK inhibitor, thus restoring neurogenesis to normal levels. Silencing STAT3 expression by lentiviral vectors also impaired neurogenesis by blocking the effects of IL-10. Our findings unveil ERK and STAT3 as effectors of IL-10 in adult SVZ neurogenesis. PMID:25762897

  11. Tyk2 and Stat3 Regulate Brown Adipose Tissue Differentiation and Obesity

    PubMed Central

    Derecka, Marta; Gornicka, Agnieszka; Koralov, Sergei B.; Szczepanek, Karol; Morgan, Magdalena; Raje, Vidisha; Sisler, Jennifer; Zhang, Qifang; Otero, Dennis; Cichy, Joanna; Rajewsky, Klaus; Shimoda, Kazuya; Poli, Valeria; Strobl, Birgit; Pellegrini, Sandra; Harris, Thurl E.; Seale, Patrick; Russell, Aaron P.; McAinch, Andrew J.; O’Brien, Paul E.; Keller, Susanna R.; Croniger, Colleen M.; Kordula, Tomasz; Larner, Andrew C.

    2012-01-01

    Mice lacking the Jak tyrosine kinase member Tyk2 become progressively obese due to aberrant development of Myf5+ brown adipose tissue (BAT). Tyk2 RNA levels in BAT and skeletal muscle, which shares a common progenitor with BAT, are dramatically decreased in mice placed on a high fat diet and in obese humans. Expression of Tyk2 or the constitutively active form of the transcription factor Stat3 (CAStat3) restores differentiation in Tyk2?/? brown preadipocytes. Furthermore, Tyk2?/? mice expressing CAStat3 transgene in BAT also show improved BAT development, normal levels of insulin and significantly lower body weights. Stat3 binds to PRDM16, a master regulator of BAT differentiation, and enhances the stability of PRDM16 protein. These results define Tyk2 and Stat3 as critical determinants of brown fat-lineage and suggest that altered levels of Tyk2 are associated with obesity in both rodents and humans. PMID:23217260

  12. STAT3 signalling is required for leptin regulation of energy balance but not reproduction

    Microsoft Academic Search

    Sarah H. Bates; Walter H. Stearns; Trevor A. Dundon; Markus Schubert; Annette W. K. Tso; Yongping Wang; Alexander S. Banks; Hugh J. Lavery; Asma K. Haq; Eleftheria Maratos-Flier; Benjamin G. Neel; Michael W. Schwartz; Martin G. Myers

    2003-01-01

    Secretion of leptin from adipocytes communicates body energy status to the brain by activating the leptin receptor long form (LRb). LRb regulates energy homeostasis and neuroendocrine function; the absence of LRb in db\\/db mice results in obesity, impaired growth, infertility and diabetes. Tyr 1138 of LRb mediates activation of the transcription factor STAT3 during leptin action. To investigate the contribution

  13. Nuclear translocation of phosphorylated STAT3 regulates VEGF-A-induced lymphatic endothelial cell migration and tube formation

    SciTech Connect

    Okazaki, Hideki; Tokumaru, Sho; Hanakawa, Yasushi; Shiraishi, Ken; Shirakata, Yuji; Dai, Xiuju; Yang, Lijun; Tohyama, Mikiko; Hashimoto, Koji [Department of Dermatology, Ehime University Graduate School of Medicine, Toon, Ehime 791-0295 (Japan)] [Department of Dermatology, Ehime University Graduate School of Medicine, Toon, Ehime 791-0295 (Japan); Sayama, Koji, E-mail: sayama@m.ehime-u.ac.jp [Department of Dermatology, Ehime University Graduate School of Medicine, Toon, Ehime 791-0295 (Japan)] [Department of Dermatology, Ehime University Graduate School of Medicine, Toon, Ehime 791-0295 (Japan)

    2011-09-02

    Highlights: {yields} VEGF-A enhanced lymphatic endothelial cell migration and increased tube formation. {yields} VEGF-A treated lymphatic endothelial cell showed activation of STAT3. {yields} Dominant-negative STAT3 inhibited VEGF-A-induced lymphatic endothelial cell migration and tube formation. -- Abstract: Vascular endothelial growth factor (VEGF) is an endothelial cell-specific growth factor that regulates endothelial functions, and signal transducers and activators of transcription (STATs) are known to be important during VEGF receptor signaling. The aim of this study was to determine whether STAT3 regulates VEGF-induced lymphatic endothelial cell (LEC) migration and tube formation. VEGF-A (33 ng/ml) enhanced LEC migration by 2-fold and increased tube length by 25% compared with the control, as analyzed using a Boyden chamber and Matrigel assay, respectively. Western blot analysis and immunostaining revealed that VEGF-A induced the nuclear translocation of phosphorylated STAT3 in LECs, and this translocation was blocked by the transfection of LECs with an adenovirus vector expressing a dominant-negative mutant of STAT3 (Ax-STAT3F). Transfection with Ax-STAT3F also almost completely inhibited VEGF-A-induced LEC migration and tube formation. These results indicate that STAT3 is essential for VEGF-A-induced LEC migration and tube formation and that STAT3 regulates LEC functions.

  14. Stat3 inhibits WTX expression through up-regulation of microRNA-370 in Wilms tumor.

    PubMed

    Cao, Xu; Liu, Dehong; Yan, Xiangming; Zhang, Ya; Yuan, Liqun; Zhang, Ting; Fu, Mingcui; Zhou, Yun; Wang, Jian

    2013-03-18

    Wilms tumor (WT) is a genetically heterogeneous childhood kidney tumor. Several genetic mutations have been identified in WT patients, including inactivation of WTX, somatic stabilizing CTNNB1, and p53 mutations. However, the molecular mechanisms in tumorigenesis remain largely unexplored. Stat3 is a transcription factor that can promote oncogenesis. Stat3 activation is commonly viewed as crucial for multiple tumor proliferation and metastasis. We show that Stat3 is highly activated in Wilms tumor tissues compared to those in adjacent tissues. IL-6 treatment or transfection of a constitutively activated Stat3 in G401 cells promotes cell proliferation. At the molecular level, we further elucidate that Stat3 inhibits WTX expression through up-regulation of microRNA-370. Our results suggest that Stat3/miR-370/WTX regulatory axis might be a critical mechanism in Wilms tumor cells. PMID:23333300

  15. Bidirectional regulation between TMEFF2 and STAT3 may contribute to Helicobacter pylori-associated gastric carcinogenesis.

    PubMed

    Sun, Tian-Tian; Tang, Jia-Yin; Du, Wan; Zhao, Hui-Jun; Zhao, Gang; Yang, Sheng-Li; Chen, Hao-Yan; Hong, Jie; Fang, Jing-Yuan

    2015-03-01

    The transmembrane protein with epidermal growth factor and two follistatin motifs 2 (TMEFF2) is a single-pass transmembrane protein, and it is downregulated in human gastric cancer and levels correlate with tumor progression and time of survival. However, the mechanism of its dysregulation in gastric cancer is little known. Here we investigate its regulatory mechanism and the bidirectional regulation between TMEFF2 and STAT3 in gastric carcinogenesis. TMEFF2 expression was decreased after Helicobacter pylori (H. pylori) infection in vivo and in vitro. STAT3 directly binds to the promoter of TMEFF2 and regulates H. pylori-induced TMEFF2 downregulation in normal gastric GES-1 cells and gastric cancer AGS cells. Conversely, TMEFF2 may suppress the phosphorylation of STAT3 and TMEFF2-induced downregulation of STAT3 phosphorylation may depend on SHP-1. A highly inverse correlation between the expression of TMEFF2 and pSTAT3 was also revealed in gastric tissues. We now show the deregulation mechanism of TMEFF2 in gastric carcinogenesis and identify TMEFF2 as a new target gene of STAT3. The phosphorylation of STAT3 may be negatively regulated by TMEFF2, and the bidirectional regulation between TMEFF2 and STAT3 may contribute to H. pylori-associated gastric carcinogenesis. PMID:24996057

  16. Sequence and Functional Analysis of EBNA-LP and EBNA2 Proteins from Nonhuman Primate Lymphocryptoviruses

    Microsoft Academic Search

    RONGSHENG PENG; ALEXEY V. GORDADZE; EZEQUIEL M. FUENTES PANANA; FRED WANG; JIANCHAO ZONG; GARY S. HAYWARD; JIE TAN; PAUL D. LING

    2000-01-01

    The Epstein-Barr virus (EBV) EBNA-LP and EBNA2 proteins are the first to be synthesized during establishment of latent infection in B lymphocytes. EBNA2 is a key transcriptional regulator of both viral and cellular gene expression and is essential for EBV-induced immortalization of B lymphocytes. EBNA-LP is also important for EBV-induced immortalization of B lymphocytes, but far less is known about

  17. ROLE OF PROOPIOMELANOCORTIN NEURON STAT3 IN REGULATING ARTERIAL PRESSURE AND MEDIATING THE CHRONIC EFFECTS OF LEPTIN

    PubMed Central

    Dubinion, John H.; do Carmo, Jussara M.; Adi, Ahmad; Hamza, Shereen; da Silva, Alexandre A.; Hall, John E.

    2013-01-01

    Although signal transducer and activator of transcription 3 (Stat3) is a key second messenger by which leptin regulates appetite and body weight, its role in specific neuronal populations in metabolic regulation and in mediating the chronic effects of leptin on blood pressure are unknown. The current study tested the hypothesis that Stat3 signaling in proopiomelanocortin (POMC) neurons mediates the chronic effects of leptin on mean arterial pressure (MAP) as well as on glucose regulation, energy expenditure, and food intake. Stat3flox/flox mice were crossed with POMC-Cre mice to generate mice with Stat3 deletion specifically in POMC neurons (Stat3flox/flox/POMC-Cre). Oxygen consumption (VO2), carbon dioxide respiration (VCO2), motor activity, heat production, food intake and MAP were measured 24hrs/day. After baseline measurements, leptin was infused (4?g/kg/min, IP) for 7 days. Stat3flox/flox/POMC-Cre mice were hyperphagic, heavier, and had increased respiratory quotients compared to control Stat3flox/flox mice. Baseline MAP was not different between the groups and chronic leptin infusion reduced food intake similarly in both groups (27 vs. 29%). VO2, VCO2, and heat production responses to leptin were not significantly different in control and Stat3flox/flox/POMC-Cre mice. However, leptin-mediated increases in MAP were completely abolished and blood pressure responses to acute air-jet stress were attenuated in male Stat3flox/flox/POMC-Cre mice. These results indicate that Stat3 signaling in POMC neurons is essential for leptin-mediated increases in MAP but not for leptin’s anorexic or thermogenic effects. PMID:23529161

  18. FTO contributes to hepatic metabolism regulation through regulation of leptin action and STAT3 signalling in liver

    PubMed Central

    2014-01-01

    Background The fat mass and obesity associated (FTO) gene is related to obesity and type 2 diabetes, but its function is still largely unknown. A link between leptin receptor-signal transducers and activators of transcription 3 (LepR-STAT3) signalling pathway and FTO was recently suggested in the hypothalamus. Because of the presence of FTO in liver and the role of LepR-STAT3 in the control of hepatic metabolism, we investigated both in vitro and in vivo the potential interrelationship between FTO and LepR-STAT3 signalling pathway in liver and the impact of FTO overexpression on leptin action and glucose homeostasis in liver of mice. Results We found that FTO protein expression is regulated by both leptin and IL-6, concomitantly to an induction of STAT3 tyrosine phosphorylation, in leptin receptor (LepRb) expressing HuH7 cells. In addition, FTO overexpression in vitro altered both leptin-induced Y705 and S727 STAT3 phosphorylation, leading to dysregulation of glucose-6-phosphatase (G6P) expression and mitochondrial density, respectively. In vivo, liver specific FTO overexpression in mice induced a reducetion of Y705 phosphorylation of STAT3 in nuclear fraction, associated with reduced SOCS3 and LepR mRNA levels and with an increased G6P expression. Interestingly, FTO overexpression also induced S727 STAT3 phosphorylation in liver mitochondria, resulting in an increase of mitochondria function and density. Altogether, these data indicate that FTO promotes mitochondrial recruitment of STAT3 to the detriment of its nuclear localization, affecting in turn oxidative metabolism and the expression of leptin-targeted genes. Interestingly, these effects were associated in mice with alterations of leptin action and hyperleptinemia, as well as hyperglycemia, hyperinsulinemia and glucose intolerance. Conclusions Altogether, these data point a novel regulatory loop between FTO and leptin-STAT3 signalling pathways in liver cells, and highlight a new role of FTO in the regulation of hepatic leptin action and glucose metabolism. PMID:24410832

  19. GP130-STAT3 Regulates Epithelial Cell Migration and Is Required for Repair of the Bronchiolar Epithelium

    PubMed Central

    Kida, Hiroshi; Mucenski, Michael L.; Thitoff, Angela R.; Le Cras, Timothy D.; Park, Kwon-Sik; Ikegami, Machiko; Müller, Werner; Whitsett, Jeffrey A.

    2008-01-01

    Following injury, bronchiolar cells undergo rapid squamous metaplasia, followed by proliferation and re-establishment of the complex columnar epithelium that is characteristic of the normal airway. Mechanisms that regulate the repair of bronchiolar epithelium are of considerable relevance for understanding the pathogenesis of both acute and chronic lung diseases associated with airway remodeling. This study was designed to identify the role of the GP130-STAT3 signaling pathway during repair of the bronchiolar epithelium. STAT3 (signal transducer and activator of transcription 3) and GP130 (glycoprotein 130) were each selectively deleted from the pulmonary epithelial cells of transgenic mice in vivo, producing Stat3?/? and Gp130?/? mice, respectively. Airway injury was induced in adult mice by administration of naphthalene, a toxicant of nonciliated respiratory epithelial cells (Clara cells). Nuclear STAT3 staining was induced in bronchiolar epithelial cells following naphthalene-mediated injury in control (Stat3flox/flox) mice. Whereas nearly complete repair of the bronchiolar epithelium was observed in control mice within 13 days, restoration of cell shape, cell density, and the pattern of ciliated and nonciliated cells did not occur in the peripheral bronchioles of either Stat3?/? or Gp130?/? mice. Expression of dominant-negative STAT3 inhibited airway epithelial cell migration during repair in vitro; wild-type STAT3 expression activated such migration. In the present study, we show that GP130-STAT3 signaling functions in a cell-autonomous manner to restore cell shape and numbers required for repair of the bronchiolar epithelium following injury. PMID:18467707

  20. The Ashwell-Morell receptor regulates hepatic thrombopoietin production via JAK2-STAT3 signaling

    PubMed Central

    Grozovsky, Renata; Begonja, Antonija Jurak; Liu, Kaifeng; Visner, Gary; Hartwig, John H.; Falet, Hervé; Hoffmeister, Karin M.

    2015-01-01

    The hepatic Ashwell-Morell receptor (AMR) can bind and remove desialylated platelets. We demonstrate that platelets become desialylated as they circulate and age in blood. Binding of desialylated platelets to the AMR induces hepatic thrombopoietin (TPO) gene transcription and translation, thereby regulating platelet production. The highly conserved endocytic AMR signals through Janus kinase 2 (JAK2) and the acute phase response signal transducer and activator of transcription 3 (STAT3) in vivo and in vitro. Recognition of this novel physiological feedback mechanism illuminates the pathophysiology of platelet diseases, such as Essential Thrombocythemia and Immune Thrombocytopenia, and contributes to our understanding of the mechanisms of thrombocytopenia observed with JAK1/2 inhibition. PMID:25485912

  1. Stat3 signaling regulates embryonic stem cell fate in a dose-dependent manner

    PubMed Central

    Tai, Chih-I; Schulze, Eric N.; Ying, Qi-Long

    2014-01-01

    ABSTRACT Stat3 is essential for mouse embryonic stem cell (mESC) self-renewal mediated by LIF/gp130 receptor signaling. Current understanding of Stat3-mediated ESC self-renewal mechanisms is very limited, and has heretofore been dominated by the view that Stat3 signaling functions in a binary “on/off” manner. Here, in contrast to this binary viewpoint, we demonstrate a contextual, rheostat-like mechanism for Stat3's function in mESCs. Activation and expression levels determine whether Stat3 functions in a self-renewal or a differentiation role in mESCs. We also show that Stat3 induces rapid differentiation of mESCs toward the trophectoderm (TE) lineage when its activation level exceeds certain thresholds. Stat3 induces this differentiation phenotype via induction of Tfap2c and its downstream target Cdx2. Our findings provide a novel concept in the realm of Stat3, self-renewal signaling, and pluripotent stem cell biology. Ultimately, this finding may facilitate the development of conditions for the establishment of authentic non-rodent ESCs. PMID:25238758

  2. Regulation of the innate and adaptive immune responses by Stat3 signaling in tumor cells

    Microsoft Academic Search

    Tianhong Wang; Guilian Niu; Marcin Kortylewski; Lyudmila Burdelya; Kenneth Shain; Shumin Zhang; Raka Bhattacharya; Dmitry Gabrilovich; Richard Heller; Domenico Coppola; William Dalton; Richard Jove; Drew Pardoll; Hua Yu

    2003-01-01

    Although tumor progression involves processes such as tissue invasion that can activate inflammatory responses, the immune system largely ignores or tolerates disseminated cancers. The mechanisms that block initiation of immune responses during cancer development are poorly understood. We report here that constitutive activation of Stat-3, a common oncogenic signaling pathway, suppresses tumor expression of proinflammatory mediators. Blocking Stat-3 in tumor

  3. STAT3 is a critical cell-intrinsic regulator of human unconventional T cell numbers and function.

    PubMed

    Wilson, Robert P; Ives, Megan L; Rao, Geetha; Lau, Anthony; Payne, Kathryn; Kobayashi, Masao; Arkwright, Peter D; Peake, Jane; Wong, Melanie; Adelstein, Stephen; Smart, Joanne M; French, Martyn A; Fulcher, David A; Picard, Capucine; Bustamante, Jacinta; Boisson-Dupuis, Stephanie; Gray, Paul; Stepensky, Polina; Warnatz, Klaus; Freeman, Alexandra F; Rossjohn, Jamie; McCluskey, James; Holland, Steven M; Casanova, Jean-Laurent; Uzel, Gulbu; Ma, Cindy S; Tangye, Stuart G; Deenick, Elissa K

    2015-06-01

    Unconventional T cells such as ?? T cells, natural killer T cells (NKT cells) and mucosal-associated invariant T cells (MAIT cells) are a major component of the immune system; however, the cytokine signaling pathways that control their development and function in humans are unknown. Primary immunodeficiencies caused by single gene mutations provide a unique opportunity to investigate the role of specific molecules in regulating human lymphocyte development and function. We found that individuals with loss-of-function mutations in STAT3 had reduced numbers of peripheral blood MAIT and NKT but not ?? T cells. Analysis of STAT3 mosaic individuals revealed that this effect was cell intrinsic. Surprisingly, the residual STAT3-deficient MAIT cells expressed normal levels of the transcription factor ROR?t. Despite this, they displayed a deficiency in secretion of IL-17A and IL-17F, but were able to secrete normal levels of cytokines such as IFN? and TNF. The deficiency in MAIT and NKT cells in STAT3-deficient patients was mirrored by loss-of-function mutations in IL12RB1 and IL21R, respectively. Thus, these results reveal for the first time the essential role of STAT3 signaling downstream of IL-23R and IL-21R in controlling human MAIT and NKT cell numbers. PMID:25941256

  4. Different Associations of CD45 Isoforms with STAT3, PKC and ERK Regulate IL-6-Induced Proliferation in Myeloma

    PubMed Central

    Zheng, Xu; Li, Allison S.; Zheng, Huanyu; Zhao, Dongmei; Guan, Dagang; Zou, Huawei

    2015-01-01

    In response to interleukin 6 (IL-6) stimulation, both CD45RO and CD45RB, but not CD45RA, translocate to lipid rafts. However, the significance of this distinct translocation and the downstream signals in CD45 isoforms-participated IL-6 signal are not well understood. Using sucrose fractionation, we found that phosphorylated signal transducer and activator of transcription (STAT)3 and STAT1 were mainly localized in lipid rafts in response to IL-6 stimulation, despite both STAT3 and STAT1 localizing in raft and non-raft fractions in the presence or absence of IL-6. On the other hand, extracellular signal-regulated kinase (ERK), and phosphorylated ERK were localized in non-raft fractions regardless of the existence of IL-6. The rafts inhibitor significantly impeded the phosphorylation of STAT3 and STAT1 and nuclear translocation, but had little effect on (and only postponing) the phosphorylation of ERK. This data suggests that lipid raft-dependent STAT3 and STAT1 pathways are dominant pathways of IL-6 signal in myeloma cells. Interestingly, the phosphorylation level of STAT3 but not STAT1 in CD45+ cells was significantly higher compared to that of CD45- cells, while the phosphorylation level of ERK in CD45+ myeloma cells was relatively low. Furthermore, exogenously expressed CD45RO/RB significantly enhanced STAT3, protein kinase C (PKC) and downstream NF-?B activation; however, CD45RA/RB inhibited IL-6-induced ERK phosphorylation. CD45 also enhanced the nuclear localization of STAT3 but not that of STAT1. In response to IL-6 stimulation, CD45RO moved into raft compartments and formed a complex with STAT3 and PKC in raft fraction, while CD45RA remained outside of lipid rafts and formed a complex with ERK in non-raft fraction. This data suggests a different role of CD45 isoforms in IL-6-induced signaling, indicating that while CD45RA/RB seems inhibit the rafts-unrelated ERK pathway, CD45RO/RB may actually work to enhance the rafts-related STAT3 and PKC/NF-?B pathways. PMID:25781885

  5. Regulation of PSMB5 Protein and ? Subunits of Mammalian Proteasome by Constitutively Activated Signal Transducer and Activator of Transcription 3 (STAT3)

    PubMed Central

    Vangala, Janakiram Reddy; Dudem, Srikanth; Jain, Nishant; Kalivendi, Shasi V.

    2014-01-01

    The ubiquitin-proteasome system facilitates the degradation of ubiquitin-tagged proteins and performs a regulatory role in cells. Elevated proteasome activity and subunit expression are found in several cancers. However, the inherent molecular mechanisms responsible for increased proteasome function in cancers remain unclear despite the well investigated and defined role of the mammalian proteasome. This study was initiated to elucidate the mechanisms involved in the regulation of ? subunits of the mammalian proteasome. Suppression of STAT3 tyrosine phosphorylation coordinately decreased the mRNA and protein levels of the ? subunits of the 20 S core complex in DU145 cells. Notably, PSMB5, a molecular target of bortezomib, was shown to be a target of STAT3. Knockdown of STAT3 decreased PSMB5 protein. Inhibition of phospho-STAT3 substantially reduced PSMB5 protein levels in cells expressing constitutively active-STAT3. Accumulation of activated STAT3 resulted in the induction of PSMB5 promoter and protein levels. In addition, a direct correlation was observed between the endogenous levels of PSMB5 and constitutively active STAT3. PSMB5 and STAT3 protein levels remained unaltered following the inhibition of proteasome activity. The EGF-induced concerted increase of ? subunits was blocked by inhibition of the EGF receptor or STAT3 but not by the PI3K/AKT or MEK/ERK pathways. Decreased proteasome activities were due to reduced protein levels of catalytic subunits of the proteasome in STAT3-inhibited cells. Combined treatments with bortezomib and inhibitor of STAT3 abrogated proteasome activity and enhanced cellular apoptosis. Overall, we demonstrate that aberrant activation of STAT3 regulates the expression of ? subunits, in particular PSMB5, and the catalytic activity of the proteasome. PMID:24627483

  6. esBAF Facilitates Pluripotency by Conditioning the Genome for LIF/STAT3Signalingand by Regulating Polycomb Function

    PubMed Central

    Ho, Lena; Miller, Erik L.; Ronan, Jehnna L.; Ho, Wenqi; Jothi, Raja; Crabtree, Gerald R

    2011-01-01

    Signaling by the cytokine LIF and its downstream transcription factor, STAT3, prevents differentiation of pluripotent embryonic stem cells (ESCs) by opposing MAP kinase signaling. This contrasts with most cell types where STAT3signaling induces differentiation. We find that STAT3binding across the pluripotent genome is dependent upon Brg, the ATPase subunit of a specialized chromatin remodeling complex (esBAF) found in ESCs. Brg is required to establish chromatin accessibility at STAT3 binding targets, in essence preparing these sites to respond to LIF signaling. Moreover, Brg deletion leads to rapid Polycomb (PcG) binding and H3K27me3-mediated silencing of many Brg-activated targets genome-wide, including the target genes of the LIF signaling pathway. Hence, one crucial role of Brg in ESCs involves its ability to potentiate LIF signaling by opposing PcG. Contrary to expectations, Brg also facilitates PcG function at classical PcG target including all four Hox loci, reinforcing their repression in ESCs. These findings reveal that esBAF does not simply antagonize PcG, but rather, the two chromatin regulators act both antagonistically and synergistically with the common goal of supporting pluripotency. PMID:21785422

  7. C-Terminal Region of EBNA-2 Determines the Superior Transforming Ability of Type 1 Epstein-Barr Virus by Enhanced Gene Regulation of LMP1 and CXCR7

    Microsoft Academic Search

    Laila Cancian; Rachel Bosshard; Walter Lucchesi; Claudio Elgueta Karstegl; Paul J. Farrell

    2011-01-01

    Type 1 Epstein-Barr virus (EBV) strains immortalize B lymphocytes in vitro much more efficiently than type 2 EBV, a difference previously mapped to the EBNA-2 locus. Here we demonstrate that the greater transforming activity of type 1 EBV correlates with a stronger and more rapid induction of the viral oncogene LMP-1 and the cell gene CXCR7 (which are both required

  8. Hypoxia-inducible Factor 1? Regulates a SOCS3-STAT3-Adiponectin Signal Transduction Pathway in Adipocytes*

    PubMed Central

    Jiang, Changtao; Kim, Jung-Hwan; Li, Fei; Qu, Aijuan; Gavrilova, Oksana; Shah, Yatrik M.; Gonzalez, Frank J.

    2013-01-01

    Obesity has been identified as a major risk factor for type 2 diabetes, characterized by insulin resistance in insulin target tissues. Hypoxia-inducible factor 1? (HIF1?) regulates pathways in energy metabolism that become dysregulated in obesity. Earlier studies revealed that HIF1? in adipose tissue is markedly elevated in high-fat diet-fed mice that are obese and insulin-resistant. Genetic ablation of HIF1? in adipose tissue decreased insulin resistance and obesity, accompanied by increased serum adiponectin levels. However, the exact mechanism whereby HIF1? regulates adiponectin remains unclear. Here, acriflavine (ACF), an inhibitor of HIF1?, induced the expression of adiponectin and reduced the expression of SOCS3 in cultured 3T3-L1 adipocytes. Mechanistic studies revealed that HIF1? suppressed the expression of adiponectin through a SOCS3-STAT3 pathway. Socs3 was identified as a novel HIF1? target gene based on chromatin immunoprecipitation and luciferase assays. STAT3 directly regulated adiponectin in vitro in cultured 3T3-L1 adipocytes. ACF was found to prevent diet-induced obesity and insulin resistance. In vivo, ACF also regulated the SOCS3-STAT3-adiponectin pathway, and inhibition of HIF1? in adipose tissue was essential for ACF to improve the SOCS3-STAT3-adiponectin pathway to counteract insulin resistance. This study provides evidence for a novel target gene and signal transduction pathway in adipocytes and indicates that inhibitors of HIF1? have potential utility for the treatment of obesity and type 2 diabetes. PMID:23255598

  9. Constitutive Stat3 activity up-regulates VEGF expression and tumor angiogenesis

    Microsoft Academic Search

    Guilian Niu; Kenneth L Wright; Mei Huang; Lanxi Song; Eric Haura; James Turkson; Shumin Zhang; Tianhong Wang; Dominic Sinibaldi; Domenico Coppola; Richard Heller; Lee M Ellis; James Karras; Jacqueline Bromberg; Drew Pardoll; Richard Jove; Hua Yu; H Yu

    2002-01-01

    Non-receptor and receptor tyrosine kinases, such as Src and EGF receptor (EGFR), are major inducers of vascular endothelial growth factor (VEGF), one of the most potent mediators of angiogenesis. While tyrosine kinases signal through multiple pathways, signal transducer and activation of transcription 3 (Stat3) is a point of convergence for many of these and is constitutively activated with high frequency

  10. CCR7 Regulates Cell Migration and Invasion through JAK2/STAT3 in Metastatic Squamous Cell Carcinoma of the Head and Neck

    PubMed Central

    Liu, Fa-Yu; Safdar, Jawad; Li, Zhen-Ning; Fang, Qi-Gen; Zhang, Xu; Xu, Zhong-Fei; Sun, Chang-Fu

    2014-01-01

    Squamous cell carcinoma of the head and neck (SCCHN) frequently involves metastasis at diagnosis. Our previous research has demonstrated that CCR7 plays a key role in regulating SCCHN metastasis, and this process involves several molecules, such as PI3K/cdc42, pyk2, and Src. In this study, the goals are to identify whether JAK2/STAT3 also participates in CCR7's signal network, its relationship with other signal pathways, and its role in SCCHN cell invasion and migration. The results showed that stimulation of CCL19 could induce JAK2/STAT3 phosphorylation, which can be blocked by Src and pyk2 inhibitors. After activation, STAT3 was able to promote low expression of E-cadherin and had no effect on vimentin. This JAk2/STAT3 pathway not only mediated CCR7-induced cell migration but also mediated invasion speed. The immunohistochemistry results also showed that the phosphorylation of STAT3 was correlated with CCR7 expression in SCCHN, and CCR7 and STAT3 phosphorylation were all associated with lymph node metastasis. In conclusion, JAk2/STAT3 plays a key role in CCR7 regulating SCCHN metastasis. PMID:25405202

  11. PCBP2 regulates hepatic insulin sensitivity via HIF-1? and STAT3 pathway in HepG2 cells.

    PubMed

    Xia, Nana; Tang, Zhuqi; Wang, Cuifang; Xu, Guangfei; Nie, Xiaoke; Zhang, Wanlu; Zhao, Yun; Wang, Suxin; Zhu, Xiaohui; Cui, Shiwei

    2015-07-17

    Elevated free fatty acids (FFAs) are fundamental to the pathogenesis of hepatic insulin resistance. However, the molecular mechanisms of insulin resistance remain not completely understood. Transcriptional dysregulation, post-transcriptional modifications and protein degradation contribute to the pathogenesis of insulin resistance. Poly(C) binding proteins (PCBPs) are RNA-binding proteins that are involved in post-transcriptional control pathways. However, there are little studies about the roles of PCBPs in insulin resistance. PCBP2 is the member of the RNA-binding proteins and is thought to participate in regulating hypoxia inducible factor-1 (HIF-1?) and signal transducers and activators of transcription (STAT) pathway which are involved in regulating insulin signaling pathway. Here, we investigated the influence of PCBP2 on hepatic insulin resistance. We showed that the protein and mRNA levels of PCBP2 were down-regulated under insulin-resistant conditions. In addition, we showed that over-expression of PCBP2 ameliorates palmitate (PA)-induced insulin resistance, which was indicated by elevated phosphorylation of protein kinase B (AKT) and glycogen synthase kinase 3? (GSK3?). We also found that over-expression of PCBP2 inhibits HIF1? and STAT3 pathway. Furthermore, glucose uptake was found to display a similar tendency with the phosphorylation of Akt. The expressions of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase), two key gluconeogenic enzymes, were down-regulated following Over-expression of PCBP2. Accordingly, PA-induced intracellular lipid accumulation was suppressed in over-expression of PCBP2 HepG2 cells. In addition, we found that over-expression of PCBP2 inhibits HIF1? and STAT3 pathway. Our results demonstrate that PCBP2 was involved in hepatic insulin sensitivity might via HIF-1? and STAT3 pathway in HepG2 cells. PMID:26002461

  12. N-myc downstream-regulated gene 2 (NDRG2) suppresses the epithelial-mesenchymal transition (EMT) in breast cancer cells via STAT3/Snail signaling.

    PubMed

    Kim, Myung-Jin; Lim, Jihyun; Yang, Young; Lee, Myeong-Sok; Lim, Jong-Seok

    2014-11-01

    Although NDRG2 has recently been found to be a candidate tumor suppressor, its precise role in the epithelial-mesenchymal transition (EMT) is not well understood. In the present study, we demonstrated that NDRG2 overexpression in MDA-MB-231 cells down-regulated the expression of Snail, a transcriptional repressor of E-cadherin and a key regulator of EMT, as well as the phosphorylation of signal transducer and activator of transcription 3 (STAT3), an oncogenic transcription factor that is activated in many human malignancies including breast cancer. In addition, we confirmed that the expression of Snail and phospho-STAT3 was recovered when NDRG2 was knocked down by siRNA in MCF7 cells in which NDRG2 is endogenously expressed. Interestingly, MDA-MB-231-NDRG2 cells showed remarkably decreased Snail expression after treatment with JSI-124 (also known as cucurbitacin I) or Stattic, STAT3 inhibitors, compared to MDA-MB-231-mock cells. Moreover, STAT3 activation by EGF treatment induced higher Snail expression, and NDRG2 overexpression resulted in the inhibition of Snail expression in MDA-MB-231 cells stimulated by EGF in the absence or presence of STAT3 inhibitor. Treatment of MDA-MB-231 cells with STAT3 inhibitor led to a moderate decrease in wound healing and migration capacity, whereas STAT3 inhibitor treatment of MDA-MB-231-NDRG2 cells resulted in a significant attenuation of migration in both resting and EGF-stimulated cells. Collectively, our data demonstrate that the inhibition of STAT3 signaling by NDRG2 suppresses EMT progression of EMT via the down-regulation of Snail expression. PMID:25153349

  13. The EBNA-2 N-Terminal Transactivation Domain Folds into a Dimeric Structure Required for Target Gene Activation

    PubMed Central

    Hennig, Janosch; Zou, Peijian; Nössner, Elfriede; Ling, Paul D.; Sattler, Michael; Kempkes, Bettina

    2015-01-01

    Epstein-Barr virus (EBV) is a ?-herpesvirus that may cause infectious mononucleosis in young adults. In addition, epidemiological and molecular evidence links EBV to the pathogenesis of lymphoid and epithelial malignancies. EBV has the unique ability to transform resting B cells into permanently proliferating, latently infected lymphoblastoid cell lines. Epstein-Barr virus nuclear antigen 2 (EBNA-2) is a key regulator of viral and cellular gene expression for this transformation process. The N-terminal region of EBNA-2 comprising residues 1-58 appears to mediate multiple molecular functions including self-association and transactivation. However, it remains to be determined if the N-terminus of EBNA-2 directly provides these functions or if these activities merely depend on the dimerization involving the N-terminal domain. To address this issue, we determined the three-dimensional structure of the EBNA-2 N-terminal dimerization (END) domain by heteronuclear NMR-spectroscopy. The END domain monomer comprises a small fold of four ?-strands and an ?-helix which form a parallel dimer by interaction of two ?-strands from each protomer. A structure-guided mutational analysis showed that hydrophobic residues in the dimer interface are required for self-association in vitro. Importantly, these interface mutants also displayed severely impaired self-association and transactivation in vivo. Moreover, mutations of solvent-exposed residues or deletion of the ?-helix do not impair dimerization but strongly affect the functional activity, suggesting that the EBNA-2 dimer presents a surface that mediates functionally important intra- and/or intermolecular interactions. Our study shows that the END domain is a novel dimerization fold that is essential for functional activity. Since this specific fold is a unique feature of EBNA-2 it might provide a novel target for anti-viral therapeutics. PMID:26024477

  14. Astrocyte response to motor neuron injury promotes structural synaptic plasticity via STAT3-regulated TSP-1 expression

    PubMed Central

    Tyzack, Giulia E.; Sitnikov, Sergey; Barson, Daniel; Adams-Carr, Kerala L.; Lau, Nike K.; Kwok, Jessica C.; Zhao, Chao; Franklin, Robin J. M.; Karadottir, Ragnhildur T.; Fawcett, James W.; Lakatos, András

    2014-01-01

    The role of remote astrocyte (AC) reaction to central or peripheral axonal insult is not clearly understood. Here we use a transgenic approach to compare the direct influence of normal with diminished AC reactivity on neuronal integrity and synapse recovery following extracranial facial nerve transection in mice. Our model allows straightforward interpretations of AC–neuron signalling by reducing confounding effects imposed by inflammatory cells. We show direct evidence that perineuronal reactive ACs play a major role in maintaining neuronal circuitry following distant axotomy. We reveal a novel function of astrocytic signal transducer and activator of transcription-3 (STAT3). STAT3 regulates perineuronal astrocytic process formation and re-expression of a synaptogenic molecule, thrombospondin-1 (TSP-1), apart from supporting neuronal integrity. We demonstrate that, through this new pathway, TSP-1 is responsible for the remote AC-mediated recovery of excitatory synapses onto axotomized motor neurons in adult mice. These data provide new targets for neuroprotective therapies via optimizing AC-driven plasticity. PMID:25014177

  15. RhoC Regulates Cancer Stem Cells in Head and Neck Squamous Cell Carcinoma by Overexpressing IL-6 and Phosphorylation of STAT3

    PubMed Central

    Islam, Mozaffarul; Sharma, Smita; Teknos, Theodoros N.

    2014-01-01

    In this study we investigated the correlation between RhoC expression and cancer stem cells (CSCs) formation in head and neck squamous cell carcinoma (HNSCC). The inhibition of RhoC function was achieved using shRNA. The expression of stem cell surface markers, ALDH and CD44 were significantly low in two RhoC depleted HNSCC cell carcinoma cell lines. Furthermore, a striking reduction in tumorsphere formation was achieved in RhoC knockdown lines. The mRNA expression of RhoC in RhoC knockdown adherent and tumorspheres are dramatically down regulated as compared with the scrambled control. The mRNA expression of stem cell transcription factors; nanog, oct3/4 (Pouf1), and sox2 were significantly depleted in RhoC knockdown clones. Further, the phosphorylation of STAT3ser727, and STAT3tyr705 were significantly down regulated in RhoC knockdown clones. The overexpression of STAT3 in RhoC knockdown did not show any change in expression patterns of either-STAT3tyr705 or stem cell transcription factors, signifying the role of RhoC in STAT3 activation and thus the expression of nanog, oct3/4 and sox2 in HNSCC. The expression of Inter leukin-6 (IL-6) in RhoC knockdown HNSCC cell lines was dramatically low as compared to the scrambled control. Further, we have shown a rescue in STAT3 phosphorylation by IL-6 stimulation in RhoC knockdown lines. This study is the first of its kind to establish the involvement of RhoC in STAT3 phosphorylation and hence in promoting the activation of core cancer stem cells (CSCs) transcription factors. These findings suggest that RhoC may be a novel target for HNSCC therapy. PMID:24533098

  16. Zinc Regulates the Acute Phase Response and Serum Amyloid A Production in Response to Sepsis through JAK-STAT3 Signaling

    PubMed Central

    Liu, Ming-Jie; Bao, Shengying; Napolitano, Jessica R.; Burris, Dara L.; Yu, Lianbo; Tridandapani, Susheela; Knoell, Daren L.

    2014-01-01

    Sepsis rapidly activates the host inflammatory response and acute phase response. Severe sepsis, complicated by multiple organ failure, is associated with overwhelming inflammation and high mortality. We previously observed that zinc (Zn) deficiency significantly increases mortality in a mouse model of polymicrobial sepsis due to over-activation of the inflammatory response. In order to identify potential mechanisms that account for Zn-responsive effects, we generated whole exome expression profiles from the lung tissue of septic mice that were maintained on Zn modified diets. Based on systems analysis, we observed that Zn deficiency enhances the acute phase response and particularly the JAK-STAT3 pathway, resulting in increased serum amyloid A production. In vitro studies of primary hepatocytes and HepG2 cells substantiated that Zn-deficiency augments serum amyloid A production through up-regulation of the JAK-STAT3 and NF-?B pathways. In contrast, Zn inhibited STAT3 activation through the up-regulation of SHP1 activity. Collectively, these findings demonstrate that Zn deficiency enhances the acute phase response through up-regulation of the JAK-STAT3 pathway, thereby perpetuating increased inflammation that may lead to increased morbidity and mortality in response to sepsis. PMID:24732911

  17. Touched and Moved by STAT3

    NSDL National Science Digital Library

    S. Paul Gao (New York NY; Memorial Sloan-Kettering Cancer Center REV)

    2006-07-11

    STAT3, a member of the signal transducer and activator of transcription (STAT) family of transcription factors, is a known regulator of cell motility through its transcriptional activating functions. However, new evidence suggests a novel role for non–tyrosine-phosphorylated and cytoplasmically localized STAT3 in mediating cell migration by disrupting an interaction between microtubules and one of its partners, stathmin. The association of STAT3 with stathmin potentiates microtubule polymerization and cell movement.

  18. Constitutive Activation of Signal Transducer and Activator of Transcription 3 (STAT3) and Nuclear Factor ?B Signaling in Glioblastoma Cancer Stem Cells Regulates the Notch Pathway*

    PubMed Central

    Garner, Jo Meagan; Fan, Meiyun; Yang, Chuan He; Du, Ziyun; Sims, Michelle; Davidoff, Andrew M.; Pfeffer, Lawrence M.

    2013-01-01

    Malignant gliomas are locally aggressive, highly vascular tumors that have a dismal prognosis, and present therapies provide little improvement in the disease course and outcome. Many types of malignancies, including glioblastoma, originate from a population of cancer stem cells (CSCs) that are able to initiate and maintain tumors. Although CSCs only represent a small fraction of cells within a tumor, their high tumor-initiating capacity and therapeutic resistance drives tumorigenesis. Therefore, it is imperative to identify pathways associated with CSCs to devise strategies to selectively target them. In this study, we describe a novel relationship between glioblastoma CSCs and the Notch pathway, which involves the constitutive activation of STAT3 and NF-?B signaling. Glioma CSCs were isolated and maintained in vitro using an adherent culture system, and the biological properties were compared with the traditional cultures of CSCs grown as multicellular spheres under nonadherent culture conditions. Interestingly, both adherent and spheroid glioma CSCs show constitutive activation of the STAT3/NF-?B signaling pathway and up-regulation of STAT3- and NF-?B-dependent genes. Gene expression profiling also identified components of the Notch pathway as being deregulated in glioma CSCs, and the deregulated expression of these genes was sensitive to treatment with STAT3 and NF-?B inhibitors. This finding is particularly important because Notch signaling appears to play a key role in CSCs in a variety of cancers and controls cell fate determination, survival, proliferation, and the maintenance of stem cells. The constitutive activation of STAT3 and NF-?B signaling pathways that leads to the regulation of Notch pathway genes in glioma CSCs identifies novel therapeutic targets for the treatment of glioma. PMID:23902772

  19. Fad104, a Positive Regulator of Adipocyte Differentiation, Suppresses Invasion and Metastasis of Melanoma Cells by Inhibition of STAT3 Activity

    PubMed Central

    Katoh, Daiki; Nishizuka, Makoto; Osada, Shigehiro; Imagawa, Masayoshi

    2015-01-01

    Metastasis is the main cause of death in patients with cancer, and understanding the mechanisms of metastatic processes is essential for the development of cancer therapy. Although the role of several cell adhesion, migration or proliferation molecules in metastasis is established, a novel target for cancer therapy remains to be discovered. Previously, we reported that fad104 (factor for adipocyte differentiation 104), a regulatory factor of adipogenesis, regulates cell adhesion and migration. In this report, we clarify the role of fad104 in the invasion and metastasis of cancer cells. The expression level of fad104 in highly metastatic melanoma A375SM cells was lower than that in poorly metastatic melanoma A375C6 cells. Reduction of fad104 expression enhanced the migration and invasion of melanoma cells, while over-expression of FAD104 inhibited migration and invasion. In addition, melanoma cells stably expressing FAD104 showed a reduction in formation of lung colonization compared with control cells. FAD104 interacted with STAT3 and down-regulated the phosphorylation level of STAT3 in melanoma cells. These findings together demonstrate that fad104 suppressed the invasion and metastasis of melanoma cells by inhibiting activation of the STAT3 signaling pathway. These findings will aid a comprehensive description of the mechanism that controls the invasion and metastasis of cancer cells. PMID:25671570

  20. Granulin, a novel STAT3-interacting protein, enhances STAT3 transcriptional function and correlates with poorer prognosis in breast cancer

    PubMed Central

    Yeh, Jennifer E.; Kreimer, Simion; Walker, Sarah R.; Emori, Megan M.; Krystal, Hannah; Richardson, Andrea; Ivanov, Alexander R.; Frank, David A.

    2015-01-01

    Since the neoplastic phenotype of a cell is largely driven by aberrant gene expression patterns, increasing attention has been focused on transcription factors that regulate critical mediators of tumorigenesis such as signal transducer and activator of transcription 3 (STAT3). As proteins that interact with STAT3 may be key in addressing how STAT3 contributes to cancer pathogenesis, we took a proteomics approach to identify novel STAT3-interacting proteins. We performed mass spectrometry-based profiling of STAT3-containing complexes from breast cancer cells that have constitutively active STAT3 and are dependent on STAT3 function for survival. We identified granulin (GRN) as a novel STAT3-interacting protein that was necessary for both constitutive and maximal leukemia inhibitory factor (LIF)induced STAT3 transcriptional activity. GRN enhanced STAT3 DNA binding and also increased the time-integrated amount of LIF-induced STAT3 activation in breast cancer cells. Furthermore, silencing GRN neutralized STAT3-mediated tumorigenic phenotypes including viability, clonogenesis, and migratory capacity. In primary breast cancer samples, GRN mRNA levels were positively correlated with STAT3 gene expression signatures and with reduced patient survival. These studies identify GRN as a functionally important STAT3-interacting protein that may serve as an important prognostic biomarker and potential therapeutic target in breast cancer. PMID:26000098

  1. A STAT3-mediated metabolic switch is involved in tumour transformation and STAT3 addiction

    PubMed Central

    Demaria, Marco; Giorgi, Carlotta; Lebiedzinska, Magdalena; Esposito, Giovanna; D'Angeli, Luca; Bartoli, Antonietta; Gough, Daniel J.; Turkson, James; Levy, David E.; Watson, Christine J.; Wieckowski, Mariusz R.; Provero, Paolo; Pinton, Paolo; Poli, Valeria

    2010-01-01

    The pro-oncogenic transcription factor STAT3 is constitutively activated in a wide variety of tumours that often become addicted to its activity, but no unifying view of a core function determining this widespread STAT3-dependence has yet emerged. We show here that constitutively active STAT3 acts as a master regulator of cell metabolism, inducing aerobic glycolysis and down-regulating mitochondrial activity both in primary fibroblasts and in STAT3-dependent tumour cell lines. As a result, cells are protected from apoptosis and senescence while becoming highly sensitive to glucose deprivation. We show that enhanced glycolysis is dependent on HIF-1? up-regulation, while reduced mitochondrial activity is HIF-1?-independent and likely caused by STAT3-mediated down-regulation of mitochondrial proteins. The induction of aerobic glycolysis is an important component of STAT3 pro-oncogenic activities, since inhibition of STAT3 tyrosine phosphorylation in the tumour cell lines down-regulates glycolysis prior to leading to growth arrest and cell death, both in vitro and in vivo. We propose that this novel, central metabolic role is at the core of the addiction for STAT3 shown by so many biologically different tumours. PMID:21084727

  2. The Complex Role of STAT3 in Viral Infections

    PubMed Central

    Kuchipudi, Suresh V.

    2015-01-01

    Signal transducer and activators of transcription-3 (STAT3) regulates diverse biological functions including cell growth, differentiation, and apoptosis. In addition, STAT3 plays a key role in regulating host immune and inflammatory responses and in the pathogenesis of many cancers. Several studies reported differential regulation of STAT3 in a range of viral infections. Interestingly, STAT3 appears to direct seemingly contradictory responses and both pro- and antiviral roles of STAT3 have been described. This review summarized the currently known functions of STAT3 in the regulation of viral replication and pathogenesis of viral infections. Some of the key unanswered questions and the gap in our current understanding of the role of STAT3 in viral pathogenesis are discussed. PMID:26199948

  3. Paeoniflorin inhibits human gastric carcinoma cell proliferation through up-regulation of microRNA-124 and suppression of PI3K/Akt and STAT3 signaling

    PubMed Central

    Zheng, Yong-Bin; Xiao, Gao-Chun; Tong, Shi-Lun; Ding, Yu; Wang, Qiu-Shuang; Li, Sheng-Bo; Hao, Zhi-Nan

    2015-01-01

    AIM: To examine the potential anti-tumor activity of paeoniflorin in the human gastric carcinoma cell line MGC-803. METHODS: Cell viability and cytotoxic effects in MGC-803 cells were analyzed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assay, respectively. Cell apoptosis of MGC-803 cells was measured using flow cytometry, DAPI staining assay and caspase-3 activity assay. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to measure the expression of microRNA-124 (miR-124) in response to paeoniflorin. The expression of phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), phospho-Akt (p-Akt) and phospho-signal transducer and activator of transcription 3 (p-STAT3) were also measured by quantitative RT-PCR and Western blot analysis in normal, miR-124 and anti-miR-124 over-expressing MGC-803 cells, treated with paeoniflorin. RESULTS: Paeoniflorin was found to inhibit MGC-803 cell viability in a dose-dependent manner. Paeoniflorin treatment was associated with the induction of apoptosis and caspase-3 activity in MGC-803 cells. Paeoniflorin treatment significantly increased miR-124 levels and inhibited the expression of PI3K, Akt, p-Akt and p-STAT3 in MGC-803 cells. Interestingly, the over-expression of miR-124 inhibits PI3K/Akt and phospho-STAT3 expressions in MGC-803 cells. PI3K agonist (IGF-1, 1 ?g/10 ?L) or over-expression of STAT3 reversed the effect of paeoniflorin on the proliferation of MGC-803 cells. Over-expression of anti-miR-124 in MGC-803 cells reversed paeoniflorin-induced up-regulation. CONCLUSION: In summary, the in vitro data suggest that paeoniflorin is a potential novel therapeutic agent against gastric carcinoma, which inhibits cell viability and induces apoptosis through the up-regulation of miR-124 and suppression of PI3K/Akt and STAT3 signaling. PMID:26109806

  4. The role of STAT3 in autophagy.

    PubMed

    You, Liangkun; Wang, Zhanggui; Li, Hongsen; Shou, Jiawei; Jing, Zhao; Xie, Jiansheng; Sui, Xinbing; Pan, Hongming; Han, Weidong

    2015-05-01

    Autophagy is an evolutionarily conserved process in eukaryotes that eliminates harmful components and maintains cellular homeostasis in response to a series of extracellular insults. However, these insults may trigger the downstream signaling of another prominent stress responsive pathway, the STAT3 signaling pathway, which has been implicated in multiple aspects of the autophagic process. Recent reports further indicate that different subcellular localization patterns of STAT3 affect autophagy in various ways. For example, nuclear STAT3 fine-tunes autophagy via the transcriptional regulation of several autophagy-related genes such as BCL2 family members, BECN1, PIK3C3, CTSB, CTSL, PIK3R1, HIF1A, BNIP3, and microRNAs with targets of autophagy modulators. Cytoplasmic STAT3 constitutively inhibits autophagy by sequestering EIF2AK2 as well as by interacting with other autophagy-related signaling molecules such as FOXO1 and FOXO3. Additionally, the mitochondrial translocation of STAT3 suppresses autophagy induced by oxidative stress and may effectively preserve mitochondria from being degraded by mitophagy. Understanding the role of STAT3 signaling in the regulation of autophagy may provide insight into the classic autophagy model and also into cancer therapy, especially for the emerging targeted therapy, because a series of targeted agents execute antitumor activities via blocking STAT3 signaling, which inevitably affects the autophagy pathway. Here, we review several of the representative studies and the current understanding in this particular field. PMID:25951043

  5. Mitochondrial STAT3 supports Ras-dependent oncogenic transformation.

    PubMed

    Gough, Daniel J; Corlett, Alicia; Schlessinger, Karni; Wegrzyn, Joanna; Larner, Andrew C; Levy, David E

    2009-06-26

    Signal transducer and activator of transcription 3 (STAT3) is a latent cytoplasmic transcription factor responsive to cytokine signaling and tyrosine kinase oncoproteins by nuclear translocation when it is tyrosine-phosphorylated. We report that malignant transformation by activated Ras is impaired without STAT3, in spite of the inability of Ras to drive STAT3 tyrosine phosphorylation or nuclear translocation. Moreover, STAT3 mutants that cannot be tyrosine-phosphorylated, that are retained in the cytoplasm, or that cannot bind DNA nonetheless supported Ras-mediated transformation. Unexpectedly, STAT3 was detected within mitochondria, and exclusive targeting of STAT3 to mitochondria without nuclear accumulation facilitated Ras transformation. Mitochondrial STAT3 sustained altered glycolytic and oxidative phosphorylation activities characteristic of cancer cells. Thus, in addition to its nuclear transcriptional role, STAT3 regulates a metabolic function in mitochondria, supporting Ras-dependent malignant transformation. PMID:19556508

  6. The Epstein-Barr virus EBNA-2 gene in oral hairy leukoplakia: strain variation, genetic recombination, and transcriptional expression.

    PubMed Central

    Walling, D M; Perkins, A G; Webster-Cyriaque, J; Resnick, L; Raab-Traub, N

    1994-01-01

    Oral hairy leukoplakia (HLP) lesions frequently contain defective Epstein-Barr virus (EBV) genomes with deletions in the EBNA-2 gene that abundantly replicate and persist within the lesion. To characterize these viral strains and recombinant variants, the EBNA-2 gene in EBV DNA from several different HLP biopsy specimens was analyzed. Amplification of EBNA-2 coding sequences by PCR demonstrated the presence in HLP of intact EBNA-2 genes as well as a variety of internally deleted variants of both EBNA-2A and EBNA-2B. Some of the deletion variants evolved within the HLP lesion from intact EBNA-2 genes, while other variants appeared to be transmissible strains that directly infected the lesion. Intrastrain recombination within the HLP lesion also generated variation within the EBNA-2 polyproline region. Cloning and sequencing of HLP cDNA demonstrated transcription from the internally deleted EBNA-2 open reading frame, indicating that these variant genes are expressed in HLP. Comparative analysis of the HLP EBNA-2 sequences confirmed previous findings of EBV coinfection with multiple types and strains. Sequence variation of these wild-type genes demonstrated that EBNA-2A sequences distinguish at least two separate strains and a variety of substrains of EBV type 1. Two of the HLP EBNA-2A sequences contained amino acid changes in a cytotoxic T-cell epitope within an otherwise highly conserved region of the gene. These data indicate that EBV coinfection, strain variation, and recombination within the EBNA-2 gene are common features of HLP and suggest that the expression of internally deleted EBNA-2 variants could contribute to EBV pathogenesis in permissive infection. Images PMID:7966582

  7. Red ginseng extract ameliorates autoimmune arthritis via regulation of STAT3 pathway, Th17/Treg balance, and osteoclastogenesis in mice and human.

    PubMed

    Jhun, JooYeon; Lee, Jennifer; Byun, Jae-Kyeong; Kim, Eun-Kyung; Woo, Jung-Won; Lee, Jae-Ho; Kwok, Seung-Ki; Ju, Ji-Hyeon; Park, Kyung-Su; Kim, Ho-Youn; Park, Sung Hwan; Cho, Mi-La

    2014-01-01

    Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic joint inflammation. Red ginseng is a steamed and dried Panax ginseng C.A. Meyer, which has been used as alternative medicine for thousands of years. This study was undertaken to investigate the effects of red ginseng extracts (RGE) on autoimmune arthritis in mice and humans and to delineate the underlying mechanism. RGE was orally administered three times a week to mice with arthritis. Oral administration of RGE markedly ameliorated clinical arthritis score and histologically assessed joint inflammation in mice with CIA. A significant reduction in STAT3 phosphorylation and a decrease in the number of Th17 cells were observed with RGE treatment. There was also a marked reduction in RANKL-induced osteoclastogenesis with treatment of RGE. The inhibitory effect of RGE on Th17 differentiation and osteoclastogenesis observed in mice was also confirmed in the subsequent experiments performed using human peripheral blood mononuclear cells. Our findings provide the first evidence that RGE can regulate Th17 and reciprocally promote Treg cells by inhibiting the phosphorylation of STAT3. Therefore, RGE can ameliorate arthritis in mice with CIA by targeting pathogenic Th17 and osteoclast differentiation, suggesting a novel therapy for treatment of RA. PMID:25147435

  8. Red Ginseng Extract Ameliorates Autoimmune Arthritis via Regulation of STAT3 Pathway, Th17/Treg Balance, and Osteoclastogenesis in Mice and Human

    PubMed Central

    Jhun, JooYeon; Lee, Jennifer; Byun, Jae-Kyeong; Kim, Eun-Kyung; Woo, Jung-Won; Lee, Jae-Ho; Kwok, Seung-Ki; Ju, Ji-Hyeon; Park, Kyung-Su; Kim, Ho-Youn; Cho, Mi-La

    2014-01-01

    Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic joint inflammation. Red ginseng is a steamed and dried Panax ginseng C.A. Meyer, which has been used as alternative medicine for thousands of years. This study was undertaken to investigate the effects of red ginseng extracts (RGE) on autoimmune arthritis in mice and humans and to delineate the underlying mechanism. RGE was orally administered three times a week to mice with arthritis. Oral administration of RGE markedly ameliorated clinical arthritis score and histologically assessed joint inflammation in mice with CIA. A significant reduction in STAT3 phosphorylation and a decrease in the number of Th17 cells were observed with RGE treatment. There was also a marked reduction in RANKL-induced osteoclastogenesis with treatment of RGE. The inhibitory effect of RGE on Th17 differentiation and osteoclastogenesis observed in mice was also confirmed in the subsequent experiments performed using human peripheral blood mononuclear cells. Our findings provide the first evidence that RGE can regulate Th17 and reciprocally promote Treg cells by inhibiting the phosphorylation of STAT3. Therefore, RGE can ameliorate arthritis in mice with CIA by targeting pathogenic Th17 and osteoclast differentiation, suggesting a novel therapy for treatment of RA. PMID:25147435

  9. MafB is a downstream target of the IL-10/STAT3 signaling pathway, involved in the regulation of macrophage de-activation.

    PubMed

    Gemelli, Claudia; Zanocco Marani, Tommaso; Bicciato, Silvio; Mazza, Emilia M C; Boraschi, Diana; Salsi, Valentina; Zappavigna, Vincenzo; Parenti, Sandra; Selmi, Tommaso; Tagliafico, Enrico; Ferrari, Sergio; Grande, Alexis

    2014-05-01

    In spite of the numerous reports implicating MafB transcription factor in the molecular control of monocyte-macrophage differentiation, the precise genetic program underlying this activity has been, to date, poorly understood. To clarify this issue, we planned a number of experiments that were mainly conducted on human primary macrophages. In this regard, a preliminary gene function study, based on MafB inactivation and over-expression, indicated MMP9 and IL-7R genes as possible targets of the investigated transcription factor. Bioinformatics analysis of their promoter regions disclosed the presence of several putative MARE elements and a combined approach of EMSA and luciferase assay subsequently demonstrated that expression of both genes is indeed activated by MafB through a direct transcription mechanism. Additional investigation, performed with similar procedures to elucidate the biological relevance of our observation, revealed that MafB is a downstream target of the IL-10/STAT3 signaling pathway, normally inducing the macrophage de-activation process. Taken together our data support the existence of a signaling cascade by which stimulation of macrophages with the IL-10 cytokine determines a sequential activation of STAT3 and MafB transcription factors, in turn leading to an up-regulated expression of MMP9 and IL-7R genes. PMID:24472656

  10. Rapamycin inhibits both motility through down-regulation of p-STAT3 (S727) by disrupting the mTORC2 assembly and peritoneal dissemination in sarcomatoid cholangiocarcinoma.

    PubMed

    Hong, Sun Mi; Park, Chang Wook; Cha, Hyung Jin; Kwon, Jung Hee; Yun, Young Sung; Lee, Nam Gyu; Kim, Dae-Ghon; Nam, Hong Gil; Choi, Kwan Yong

    2013-02-01

    Cholangiocarcinoma (CC) is a malignant epithelium neoplasm that originates from the bile epithelium and for which there are few therapeutic strategies. The mTOR pathway involved in many cellular processes was reported to be up-regulated in various cancers. We investigated the activation of the AKT/mTOR pathway in CC cell lines with different degrees of dedifferentiation and found that rapamycin could suppress the motility and the peritoneal dissemination of sarcomatoid SCK cells. Inhibition of the mTOR pathway with rapamycin decreased significantly the number of tumor nodules and prolonged the survival rates of nude mice inoculated with sarcomatoid CC cells. Prolonged treatments with rapamycin were found to disrupt the mTORC2 assembly and to reduce the phosphorylation of STAT3 at Ser 727. Rapamycin decreased both mRNA and protein levels of MMP2 and Twist1, which are regulated by STAT3 and associated with cancer metastasis. The overexpression of STAT3 S727A lacking the phosphorylation site resulted in significantly less sensitivity to rapamycin than the overexpression of STAT3 WT. Taken together, our results suggest that rapamycin could suppress the motility of sarcomatoid CC by down-regulating p-STAT3 (S727) through the impairment of mTORC2 assembly. PMID:22875246

  11. Epstein-Barr Virus Nuclear Antigen 3C Putative Repression Domain Mediates Coactivation of the LMP1 Promoter with EBNA-2

    Microsoft Academic Search

    Jeffrey Lin; Eric Johannsen; Erle Robertson; Elliott Kieff

    2002-01-01

    The Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA-3C) regulates virus and cell genes and is essential for EBV-mediated transformation of primary B lymphocytes. EBNA-3C associates with the cellular DNA sequence-specific transcription factors RBP-J and PU.1 and coactivates the EBV LMP1 promoter with EBNA-2 in BL2 and Raji cells under conditions of restrictive growth. We now find that EBNA-3C is similar

  12. Selective oral ROCK2 inhibitor down-regulates IL-21 and IL-17 secretion in human T cells via STAT3-dependent mechanism

    PubMed Central

    Zanin-Zhorov, Alexandra; Weiss, Jonathan M.; Nyuydzefe, Melanie S.; Chen, Wei; Scher, Jose U.; Mo, Rigen; Depoil, David; Rao, Nishta; Liu, Ben; Wei, Jianlu; Lucas, Sarah; Koslow, Matthew; Roche, Maria; Schueller, Olivier; Weiss, Sara; Poyurovsky, Masha V.; Tonra, James; Hippen, Keli L.; Dustin, Michael L.; Blazar, Bruce R.; Liu, Chuan-ju; Waksal, Samuel D.

    2014-01-01

    Rho-associated kinase 2 (ROCK2) regulates the secretion of proinflammatory cytokines and the development of autoimmunity in mice. Data from a phase 1 clinical trial demonstrate that oral administration of KD025, a selective ROCK2 inhibitor, to healthy human subjects down-regulates the ability of T cells to secrete IL-21 and IL-17 by 90% and 60%, respectively, but not IFN-? in response to T-cell receptor stimulation in vitro. Pharmacological inhibition with KD025 or siRNA-mediated inhibition of ROCK2, but not ROCK1, significantly diminished STAT3 phosphorylation and binding to IL-17 and IL-21 promoters and reduced IFN regulatory factor 4 and nuclear hormone RAR-related orphan receptor ?t protein levels in T cells derived from healthy subjects or rheumatoid arthritis patients. Simultaneously, treatment with KD025 also promotes the suppressive function of regulatory T cells through up-regulation of STAT5 phosphorylation and positive regulation of forkhead box p3 expression. The administration of KD025 in vivo down-regulates the progression of collagen-induced arthritis in mice via targeting of the Th17-mediated pathway. Thus, ROCK2 signaling appears to be instrumental in regulating the balance between proinflammatory and regulatory T-cell subsets. Targeting of ROCK2 in man may therefore restore disrupted immune homeostasis and have a role in the treatment of autoimmunity. PMID:25385601

  13. mTOR mediates human trophoblast invasion through regulation of matrix-remodeling enzymes and is associated with serine phosphorylation of STAT3

    SciTech Connect

    Busch, Susann [Placenta-Lab, Department of Obstetrics, Friedrich-Schiller-University Jena, Bachstrasse 18, 07740 Jena (Germany)] [Placenta-Lab, Department of Obstetrics, Friedrich-Schiller-University Jena, Bachstrasse 18, 07740 Jena (Germany); Renaud, Stephen J. [Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario, Canada K7L3N6 (Canada)] [Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario, Canada K7L3N6 (Canada); Schleussner, Ekkehard [Placenta-Lab, Department of Obstetrics, Friedrich-Schiller-University Jena, Bachstrasse 18, 07740 Jena (Germany)] [Placenta-Lab, Department of Obstetrics, Friedrich-Schiller-University Jena, Bachstrasse 18, 07740 Jena (Germany); Graham, Charles H. [Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario, Canada K7L3N6 (Canada)] [Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario, Canada K7L3N6 (Canada); Markert, Udo R., E-mail: markert@med.uni-jena.de [Placenta-Lab, Department of Obstetrics, Friedrich-Schiller-University Jena, Bachstrasse 18, 07740 Jena (Germany)

    2009-06-10

    The intracellular signaling molecule mammalian target of rapamycin (mTOR) is essential for cell growth and proliferation. It is involved in mouse embryogenesis, murine trophoblast outgrowth and linked to tumor cell invasiveness. In order to assess the role of mTOR in human trophoblast invasion we analyzed the in vitro invasiveness of HTR-8/SVneo immortalized first-trimester trophoblast cells in conjunction with enzyme secretion upon mTOR inhibition and knockdown of mTOR protein expression. Additionally, we also tested the capability of mTOR to trigger signal transducer and activator of transcription (STAT)-3 by its phosphorylation status. Rapamycin inhibited mTOR kinase activity as demonstrated with a lower phosphorylation level of the mTOR substrate p70 S6 kinase (S6K). With the use of rapamycin and siRNA-mediated mTOR knockdown we could show that cell proliferation, invasion and secretion of matrix-metalloproteinases (MMP)-2 and -9, urokinase-like plasminogen activator (uPA) and its major physiological uPA inhibitor (PAI)-1 were inhibited. While tyrosine phosphorylation of STAT3 was unaffected by mTOR inhibition and knockdown, serine phosphorylation was diminished. We conclude that mTOR signaling is one major mechanism in a tightly regulated network of intracellular signal pathways including the JAK/STAT system to regulate invasion in human trophoblast cells by secretion of enzymes that remodel the extra-cellular matrix (ECM) such as MMP-2, -9, uPA and PAI-1. Dysregulation of mTOR may contribute to pregnancy-related pathologies caused through impaired trophoblast invasion.

  14. Targeting STAT3 affects melanoma on multiple fronts

    Microsoft Academic Search

    Marcin Kortylewski; Richard Jove; Hua Yu

    2005-01-01

    As a point of convergence for numerous oncogenic signaling pathways, STAT3 is constitutively-activated at 50 to 90% frequency in diverse human cancers, including melanoma. A critical role of STAT3 in tumor cell survival, proliferation, angiogenesis, metastasis and immune evasion has been recently demonstrated. STAT3 contributes to tumor cell growth by regulating the expression of genes that are involved in cell

  15. N-Acetylcysteine and allopurinol up-regulated the Jak/STAT3 and PI3K/Akt pathways via adiponectin and attenuated myocardial postischemic injury in diabetes.

    PubMed

    Wang, Tingting; Mao, Xiaowen; Li, Haobo; Qiao, Shigang; Xu, Aimin; Wang, Junwen; Lei, Shaoqing; Liu, Zipeng; Ng, Kwok F J; Wong, Gordon T; Vanhoutte, Paul M; Irwin, Michael G; Xia, Zhengyuan

    2013-10-01

    N-Acetylcysteine (NAC) and allopurinol (ALP) synergistically reduce myocardial ischemia reperfusion (MI/R) injury in diabetes. However, the mechanism is unclear. We postulated that NAC and ALP attenuated diabetic MI/R injury by up-regulating phosphatidylinositol 3-kinase/Akt (PI3K/Akt) and Janus kinase 2/signal transducer and activator of transcription-3 (JAK2/STAT3) pathways subsequent to adiponectin (APN) activation. Control (C) or streptozotocin-induced diabetic rats (D) were untreated or treated with NAC and ALP followed by MI/R. D rats displayed larger infarct size accompanied by decreased phosphorylation of Akt, STAT3 and decreased cardiac nitric oxide (NO) and APN levels. NAC and ALP decreased MI/R injury in D rats, enhanced phosphorylation of Akt and STAT3, and increased NO and APN. High glucose and hypoxia/reoxygenation exposure induced cell death and Akt and STAT3 inactivation in cultured cardiomyocytes, which were prevented by NAC and ALP. The PI3K inhibitor wortmannin and Jak2 inhibitor AG490 abolished the protection of NAC and ALP. Similarly, APN restored posthypoxic Akt and STAT3 activation and decreased cell death in cardiomyocytes. Gene silencing with AdipoR2 siRNA or STAT3 siRNA but not AdipoR1 siRNA abolished the protection of NAC and ALP. In conclusion, NAC and ALP prevented diabetic MI/R injury through PI3K/Akt and Jak2/STAT3 and cardiac APN may serve as a mediator via AdipoR2 in this process. PMID:23747931

  16. Mechanisms of unphosphorylated STAT3 transcription factor binding to DNA.

    PubMed

    Timofeeva, Olga A; Chasovskikh, Sergey; Lonskaya, Irina; Tarasova, Nadya I; Khavrutskii, Lyuba; Tarasov, Sergey G; Zhang, Xueping; Korostyshevskiy, Valeriy R; Cheema, Amrita; Zhang, Lihua; Dakshanamurthy, Sivanesan; Brown, Milton L; Dritschilo, Anatoly

    2012-04-20

    Phosphorylation of signal transducer and activator of transcription 3 (STAT3) on a single tyrosine residue in response to growth factors, cytokines, interferons, and oncogenes activates its dimerization, translocation to the nucleus, binding to the interferon ? (gamma)-activated sequence (GAS) DNA-binding site and activation of transcription of target genes. STAT3 is constitutively phosphorylated in various cancers and drives gene expression from GAS-containing promoters to promote tumorigenesis. Recently, roles for unphosphorylated STAT3 (U-STAT3) have been described in response to cytokine stimulation, in cancers, and in maintenance of heterochromatin stability. However, the mechanisms underlying U-STAT3 binding to DNA has not been fully investigated. Here, we explore STAT3-DNA interactions by atomic force microscopy (AFM) imaging. We observed that U-STAT3 molecules bind to the GAS DNA-binding site as dimers and monomers. In addition, we observed that U-STAT3 binds to AT-rich DNA sequence sites and recognizes specific DNA structures, such as 4-way junctions and DNA nodes, within negatively supercoiled plasmid DNA. These structures are important for chromatin organization and our data suggest a role for U-STAT3 as a chromatin/genome organizer. Unexpectedly, we found that a C-terminal truncated 67.5-kDa STAT3 isoform recognizes single-stranded spacers within cruciform structures that also have a role in chromatin organization and gene expression. This isoform appears to be abundant in the nuclei of cancer cells and, therefore, may have a role in regulation of gene expression. Taken together, our data highlight novel mechanisms by which U-STAT3 binds to DNA and supports U-STAT3 function as a transcriptional activator and a chromatin/genomic organizer. PMID:22378781

  17. Pim kinases are upregulated during Epstein-Barr virus infection and enhance EBNA2 activity

    SciTech Connect

    Rainio, Eeva-Marja [Turku Centre for Biotechnology, University of Turku/Abo Akademi University, Tykistoekatu 6B, 20520 Turku (Finland); Turku Graduate School of Biomedical Sciences, 20520 Turku (Finland); Ahlfors, Helena [Turku Centre for Biotechnology, University of Turku/Abo Akademi University, Tykistoekatu 6B, 20520 Turku (Finland); Carter, Kara L. [Department of Medicine and Microbiology, Harvard Medical School, Boston, MA 02115 (United States); Department of Molecular Genetics, Harvard Medical School, Boston, MA 02115 (United States); Channing Laboratory, Brigham and Women's Hospital, Boston, MA 02115 (United States); Ruuska, Marja [Turku Centre for Biotechnology, University of Turku/Abo Akademi University, Tykistoekatu 6B, 20520 Turku (Finland); Matikainen, Sampsa [Turku Centre for Biotechnology, University of Turku/Abo Akademi University, Tykistoekatu 6B, 20520 Turku (Finland); Department of Microbiology, National Public Health Institute, Mannerheimintie 166, 00300 Helsinki (Finland); Kieff, Elliott [Department of Medicine and Microbiology, Harvard Medical School, Boston, MA 02115 (United States); Department of Molecular Genetics, Harvard Medical School, Boston, MA 02115 (United States); Channing Laboratory, Brigham and Women's Hospital, Boston, MA 02115 (United States); Koskinen, Paeivi J. [Turku Centre for Biotechnology, University of Turku/Abo Akademi University, Tykistoekatu 6B, 20520 Turku (Finland)]. E-mail: paivi.koskinen@btk.fi

    2005-03-15

    Latent Epstein-Barr virus (EBV) infection is strongly associated with B-cell proliferative diseases such as Burkitt's lymphoma. Here we show that the oncogenic serine/threonine kinases Pim-1 and Pim-2 enhance the activity of the viral transcriptional activator EBNA2. During EBV infection of primary B-lymphocytes, the mRNA expression levels of pim genes, especially of pim-2, are upregulated and remain elevated in latently infected B-cell lines. Thus, EBV-induced upregulation of Pim kinases and Pim-stimulated EBNA2 transcriptional activity may contribute to the ability of EBV to immortalize B-cells and predispose them to malignant growth.

  18. Syndecan-1 (CD138) Modulates Triple-Negative Breast Cancer Stem Cell Properties via Regulation of LRP-6 and IL-6-Mediated STAT3 Signaling

    PubMed Central

    Vilardo, Laura; Kumar, Sampath Katakam; Kumar, Archana Vijaya; Kelsch, Reinhard; Schneider, Cornelia; Kiesel, Ludwig; Eich, Hans Theodor; Zucchi, Ileana; Reinbold, Rolland; Greve, Burkhard; Götte, Martin

    2013-01-01

    Syndecan-1 (CD138), a heparan sulfate proteoglycan, acts as a coreceptor for growth factors and chemokines and is a molecular marker associated with epithelial-mesenchymal transition during development and carcinogenesis. Resistance of Syndecan-1-deficient mice to experimentally-induced tumorigenesis has been linked to altered Wnt-responsive precursor cell pools, suggesting a potential role of Syndecan-1 in breast cancer cell stem function. However, the precise molecular mechanism is still elusive. Here, we decipher the functional impact of Syndecan-1 knockdown using RNA interference on the breast cancer stem cell phenotype of human triple-negative MDA-MB-231 and hormone receptor-positive MCF-7 cells in vitro employing an analytical flow cytometric approach. Successful Syndecan-1 siRNA knockdown was confirmed by flow cytometry. Side population measurement by Hoechst dye exclusion and Aldehyde dehydrogenase-1 activity revealed that Syndecan-1 knockdown in MDA-MB-231 cells significantly reduced putative cancer stem cell pools by 60% and 27%, respectively, compared to controls. In MCF-7 cells, Syndecan-1 depletion reduced the side population by 40% and Aldehyde dehydrogenase-1 by 50%, repectively. In MDA-MB-231 cells, the CD44(+)CD24(-/low) phenotype decreased significantly by 6% upon siRNA-mediated Syndecan-1 depletion. Intriguingly, IL-6, its receptor sIL-6R, and the chemokine CCL20, implicated in regulating stemness-associated pathways, were downregulated by >40% in Syndecan-1-silenced MDA-MB-231 cells, which showed a dysregulated response to IL-6-induced shifts in E-cadherin and vimentin expression. Furthermore, activation of STAT-3 and NFkB transcription factors and expression of a coreceptor for Wnt signaling, LRP-6, were reduced by >45% in Syndecan-1-depleted cells compared to controls. At the functional level, Syndecan-1 siRNA reduced the formation of spheres and cysts in MCF-7 cells grown in suspension culture. Our study demonstrates the viability of flow cytometric approaches in analyzing cancer stem cell function. As Syndecan-1 modulates the cancer stem cell phenotype via regulation of the Wnt and IL-6/STAT3 signaling pathways, it emerges as a promising novel target for therapeutic approaches. PMID:24392029

  19. The Epstein-Barr virus nuclear antigen 2 interacts with an EBNA2 responsive cis-element of the terminal protein 1 gene promoter.

    PubMed Central

    Zimber-Strobl, U; Kremmer, E; Grässer, F; Marschall, G; Laux, G; Bornkamm, G W

    1993-01-01

    The Epstein-Barr virus protein EBNA2 acts as a transcriptional activator of cellular and viral genes and plays a crucial role in the immortalization of human primary B-cells by EBV. We have shown previously that EBNA2 transactivates the promoters of the latent membrane antigens LMP, TP1 and TP2. The promoter of the TP1 gene was chosen as a model system to study the molecular mechanism of EBNA2 mediated transactivation. To identify an EBNA2 dependent cis-acting element, various TP1 promoter-reporter gene constructs were transfected in the absence and presence of an EBNA2 expression vector into the established B-cell line BL41-P3HR1. We were able to delineate an 81 bp EBNA2 responsive region between -258 and -177 relative to the TP1 RNA start site. The element worked in either orientation and could mediate EBNA2 dependent transactivation on a heterologous promoter. Electrophoretic mobility shift assays revealed three specific protein-DNA complexes formed with sequences of the EBNA2 responsive element. Two of these were not cell type specific, but the third was detected only in EBNA2 positive cell extracts. Gel-shift analysis in the presence of EBNA2 specific monoclonal antibodies revealed that EBNA2 is a component of the third complex. Thus, these experiments demonstrate that EBNA2 interacts with an EBNA2 responsive cis-element of the TP1 promoter. Images PMID:8381349

  20. Arsenite evokes IL-6 secretion, autocrine regulation of STAT3 signaling, and miR-21 expression, processes involved in the EMT and malignant transformation of human bronchial epithelial cells

    SciTech Connect

    Luo, Fei; Xu, Yuan [Institute of Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China); The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China); Ling, Min [Jiangsu Center for Disease Control and Prevention, Nanjing 211166, Jiangsu (China); Zhao, Yue; Xu, Wenchao [Institute of Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China); The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China); Liang, Xiao [Mental Health Center of Xuhui-CDC, Shanghai 200232 (China); Jiang, Rongrong; Wang, Bairu [Institute of Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China); The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China); Bian, Qian [Jiangsu Center for Disease Control and Prevention, Nanjing 211166, Jiangsu (China); Liu, Qizhan, E-mail: drqzliu@hotmail.com [Institute of Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China); The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China)

    2013-11-15

    Arsenite is an established human carcinogen, and arsenite-induced inflammation contributes to malignant transformation of cells, but the molecular mechanisms by which cancers are produced remain to be established. The present results showed that, evoked by arsenite, secretion of interleukin-6 (IL-6), a pro-inflammatory cytokine, led to the activation of STAT3, a transcription activator, and to increased levels of a microRNA, miR-21. Blocking IL-6 with anti-IL-6 antibody and inhibiting STAT3 activation reduced miR-21 expression. For human bronchial epithelial cells, cultured in the presence of anti-IL-6 antibody for 3 days, the arsenite-induced EMT and malignant transformation were reversed. Thus, IL-6, acting on STAT3 signaling, which up-regulates miR-21in an autocrine manner, contributes to the EMT induced by arsenite. These data define a link from inflammation to EMT in the arsenite-induced malignant transformation of HBE cells. This link, mediated through miRNAs, establishes a mechanism for arsenite-induced lung carcinogenesis. - Highlights: • Arsenite evokes IL-6 secretion. • IL-6 autocrine mediates STAT3 signaling and up-regulates miR-21expression. • Inflammation is involved in arsenite-induced EMT.

  1. Nuclear termination of STAT3 signaling through SIPAR (STAT3-Interacting Protein As a Repressor)-dependent recruitment of T cell tyrosine phosphatase TC-PTP.

    PubMed

    Ren, Fangli; Geng, Yongtao; Minami, Takayuki; Qiu, Ying; Feng, Yarui; Liu, Chunxiao; Zhao, Juan; Wang, Yinyin; Fan, Xuanzi; Wang, Yangmeng; Li, Mengdi; Li, Jun; Chang, Zhijie

    2015-07-01

    STAT3 is associated with embryo development and survival as well as proliferation and metastasis of tumor cells. In a previous study, we demonstrated that STAT3-Interacting Protein As a Repressor (SIPAR) enhances the dephosphorylation of STAT3 and negatively regulates its activity. However, it remains unclear how SIPAR inhibits phosphorylation of STAT3. Here we demonstrate that SIPAR directly interacts with T cell protein tyrosine phosphatase TC45 and enhances its association with STAT3. This interaction triggers an accelerated dephosphorylation process for STAT3. Furthermore, SIPAR inhibits the transcriptional activity of STAT3 in wild-type MEF cells but not in TC45 null MEF cells. These results suggest that SIPAR terminates the activation of STAT3 through a dephosphorylation process that is dependent upon interaction with TC45 in the nucleus. PMID:26026268

  2. Eriocalyxin B Inhibits STAT3 Signaling by Covalently Targeting STAT3 and Blocking Phosphorylation and Activation of STAT3.

    PubMed

    Yu, Xiaokui; He, Li; Cao, Peng; Yu, Qiang

    2015-01-01

    Activated STAT3 plays an important role in oncogenesis by stimulating cell proliferation and resisting apoptosis. STAT3 therefore is an attractive target for cancer therapy. We have screened a traditional Chinese herb medicine compound library and found Eriocalyxin B (EB), a diterpenoid from Isodon eriocalyx, as a specific inhibitor of STAT3. EB selectively inhibited constitutive as well as IL-6-induced phosphorylation of STAT3 and induced apoptosis of STAT3-dependent tumor cells. EB did not affect the upstream protein tyrosine kinases or the phosphatase (PTPase) of STAT3, but rather interacted directly with STAT3. The effects of EB could be abolished by DTT or GSH, suggesting a thiol-mediated covalent linkage between EB and STAT3. Site mutagenesis of cysteine in and near the SH2 domain of STAT3 identified Cys712 to be the critical amino acid for the EB-induced inactivation of STAT3. Furthermore, LC/MS/MS analyses demonstrated that an ?, ?-unsaturated carbonyl of EB covalently interacted with the Cys712 of STAT3. Computational modeling analyses also supported a direct interaction between EB and the Cys712 of STAT3. These data strongly suggest that EB directly targets STAT3 through a covalent linkage to inhibit the phosphorylation and activation of STAT3 and induces apoptosis of STAT3-dependent tumor cells. PMID:26010889

  3. Eriocalyxin B Inhibits STAT3 Signaling by Covalently Targeting STAT3 and Blocking Phosphorylation and Activation of STAT3

    PubMed Central

    Yu, Xiaokui; He, Li; Cao, Peng; Yu, Qiang

    2015-01-01

    Activated STAT3 plays an important role in oncogenesis by stimulating cell proliferation and resisting apoptosis. STAT3 therefore is an attractive target for cancer therapy. We have screened a traditional Chinese herb medicine compound library and found Eriocalyxin B (EB), a diterpenoid from Isodon eriocalyx, as a specific inhibitor of STAT3. EB selectively inhibited constitutive as well as IL-6-induced phosphorylation of STAT3 and induced apoptosis of STAT3-dependent tumor cells. EB did not affect the upstream protein tyrosine kinases or the phosphatase (PTPase) of STAT3, but rather interacted directly with STAT3. The effects of EB could be abolished by DTT or GSH, suggesting a thiol-mediated covalent linkage between EB and STAT3. Site mutagenesis of cysteine in and near the SH2 domain of STAT3 identified Cys712 to be the critical amino acid for the EB-induced inactivation of STAT3. Furthermore, LC/MS/MS analyses demonstrated that an ?, ?-unsaturated carbonyl of EB covalently interacted with the Cys712 of STAT3. Computational modeling analyses also supported a direct interaction between EB and the Cys712 of STAT3. These data strongly suggest that EB directly targets STAT3 through a covalent linkage to inhibit the phosphorylation and activation of STAT3 and induces apoptosis of STAT3-dependent tumor cells. PMID:26010889

  4. Correlation analysis of STAT3 and VEGF expression and eosinophil infiltration in nasal polyps.

    PubMed

    Cao, Qingsong; Zhang, Tao; Zhang, Jie

    2015-08-01

    The expression and distribution of signal transducer and activator of transcription 3 (STAT3), phosphorylated STAT3 (p-STAT3), and vascular endothelial growth factor (VEGF), as well as eosinophil infiltration in nasal polyps was detected to examine their roles and correlations in the nasal polyp pathogenesis. Using the streptavidin-biotin-peroxidase (SP) method, immunohistochemistry was performed on conventional paraffin sections of 30 surgery-resected polypous specimens and 10 inferior turbinate tissues that were resected during nasal septum deflection correction to detect the expression of STAT3, p-STAT3, and VEGF, as well as eosinophil infiltration. The rates of STAT3-, p-STAT3-, and VEGF-positive expression in the mucosal epithelium and glands of nasal polyps were 66.67, 56.67, and 76.67 %, respectively, values that were significantly higher than those in the inferior turbinate group. The number of eosinophils in the nasal polyps was significantly higher than in the inferior turbinate group. Expression of p-STAT3 and VEGF in nasal polyps and eosinophil infiltration was increased significantly and positively correlated, indicating that VEGF and eosinophil infiltration might be regulated by p-STAT3. Therefore, the expression of STAT3, p-STAT3, and VEGF, and eosinophil infiltration might be important factors in nasal polyp pathogenesis. PMID:25253546

  5. Mechanisms of STAT3 activation in the liver of FXR knockout mice

    PubMed Central

    Li, Guodong; Zhu, Yan; Tawfik, Ossama; Kong, Bo; Williams, Jessica A.; Zhan, Le; Kassel, Karen M.; Luyendyk, James P.; Wang, Li

    2013-01-01

    Farnesoid X receptor (FXR, Nr1h4) is a ligand-activated transcription factor belonging to the nuclear receptor superfamily. FXR is essential in maintaining bile acid (BA) homeostasis, and FXR?/? mice develop cholestasis, inflammation, and spontaneous liver tumors. The signal transducer and activator of transcription 3 (STAT3) is well known to regulate liver growth, and STAT3 is feedback inhibited by its target gene, the suppressor of cytokine signaling 3 (SOCS3). Strong activation of STAT3 was detected in FXR?/? mouse livers. However, the mechanism of STAT3 activation with FXR deficiency remains elusive. Wild-type (WT) and FXR?/? mice were used to detect STAT3 pathway activation in the liver. In vivo BA feeding or deprivation was used to determine the role of BAs in STAT3 activation, and in vitro molecular approaches were used to determine the direct transcriptional regulation of SOCS3 by FXR. STAT3 was activated in FXR?/? but not WT mice. BA feeding increased, but deprivation by cholestyramine reduced, serum inflammatory markers and STAT3 activation. Furthermore, the Socs3 gene was determined as a direct FXR target gene. The elevated BAs and inflammation, along with reduced SOCS3, collectively contribute to the activation of the STAT3 signaling pathway in the liver of FXR?/? mice. This study suggests that the constitutive activation of STAT3 may be a mechanism of liver carcinogenesis in FXR?/? mice. PMID:24091600

  6. EBNA2 Binds to Genomic Intervals Associated with Multiple Sclerosis and Overlaps with Vitamin D Receptor Occupancy

    PubMed Central

    Ricigliano, Vito A. G.; Handel, Adam E.; Sandve, Geir K.; Annibali, Viviana; Ristori, Giovanni; Mechelli, Rosella; Cader, M. Zameel; Salvetti, Marco

    2015-01-01

    Epstein-Barr virus (EBV) is a non-heritable factor that associates with multiple sclerosis (MS). However its causal relationship with the disease is still unclear. The virus establishes a complex co-existence with the host that includes regulatory influences on gene expression. Hence, if EBV contributes to the pathogenesis of MS it may do so by interacting with disease predisposing genes. To verify this hypothesis we evaluated EBV nuclear antigen 2 (EBNA2, a protein that recent works by our and other groups have implicated in disease development) binding inside MS associated genomic intervals. We found that EBNA2 binding occurs within MS susceptibility sites more than expected by chance (factor of observed vs expected overlap [O/E] = 5.392-fold, p < 2.0e-05). This remains significant after controlling for multiple genomic confounders. We then asked whether this observation is significant per se or should also be viewed in the context of other disease relevant gene-environment interactions, such as those attributable to vitamin D. We therefore verified the overlap between EBNA2 genomic occupancy and vitamin D receptor (VDR) binding sites. EBNA2 shows a striking overlap with VDR binding sites (O/E = 96.16-fold, p < 2.0e-05), even after controlling for the chromatin accessibility state of shared regions (p <0.001). Furthermore, MS susceptibility regions are preferentially targeted by both EBNA2 and VDR than by EBNA2 alone (enrichment difference = 1.722-fold, p = 0.0267). Taken together, these findings demonstrate that EBV participates in the gene-environment interactions that predispose to MS. PMID:25853421

  7. Involvement of stat3 in mouse brain development and sexual dimorphism: A proteomics approach

    Microsoft Academic Search

    Fabio Di Domenico; Gabriella Casalena; Rukhsana Sultana; Jian Cai; William M. Pierce; Marzia Perluigi; Chiara Cini; Alessandra Baracca; Giancarlo Solaini; Giorgio Lenaz; Jia Jia; Suzan Dziennis; Stephanie J. Murphy; Nabil J. Alkayed; D. Allan Butterfield

    Although the role of STAT3 in cell physiology and tissue development has been largely investigated, its involvement in the development and maintenance of nervous tissue and in the mechanisms of neuroprotection is not yet known. The potentially wide range of STAT3 activities raises the question of tissue- and gender-specificity as putative mechanisms of regulation. To explore the function of STAT3

  8. Icaritin inhibits JAK/STAT3 signaling and growth of renal cell carcinoma.

    PubMed

    Li, Shasha; Priceman, Saul J; Xin, Hong; Zhang, Wang; Deng, Jiehui; Liu, Yong; Huang, Jiabin; Zhu, Wenshan; Chen, Mingjie; Hu, Wei; Deng, Xiaomin; Zhang, Jian; Yu, Hua; He, Guangyuan

    2013-01-01

    Signal transducer and activator of transcription-3 (STAT3) is critical for cancer progression by regulating tumor cell survival, proliferation, and angiogenesis. Herein, we investigated the regulation of STAT3 activation and the therapeutic effects of Icaritin, a prenyl flavonoid derivative from Epimedium Genus, in renal cell carcinoma (RCC). Icaritin showed significant anti-tumor activity in the human and mouse RCC cell lines, 786-O and Renca, respectively. Icaritin inhibited both constitutive and IL-6-induced phospho-STAT3 (STAT3(Y705)) and reduced the level of STAT3-regulated proteins Bcl-xL, Mcl-1, Survivin, and CyclinD1 in a dose-dependent manner. Icaritin also inhibited activation of Janus-activated kinase-2 (JAK2), while it showed minimal effects on the activation of other key signaling pathways, including AKT and MAPK. Expression of the constitutively active form of STAT3 blocked Icaritin-induced apoptosis, while siRNA directed against STAT3 potentiated apoptosis. Finally, Icaritin significantly blunted RCC tumor growth in vivo, reduced STAT3 activation, and inhibited Bcl-xL and Cyclin E, as well as VEGF expression in tumors, which was associated with reduced tumor angiogenesis. Overall, these results suggest that Icaritin strongly inhibits STAT3 activation and is a potentially effective therapeutic option for the treatment of renal cell carcinoma. PMID:24324713

  9. STAT3 and sphingosine-1-phosphate in inflammation-associated colorectal cancer

    PubMed Central

    Nguyen, Andrew V; Wu, Yuan-Yuan; Lin, Elaine Y

    2014-01-01

    Accumulated evidences have demonstrated that signal transducer and activator of transcription 3 (STAT3) is a critical link between inflammation and cancer. Multiple studies have indicated that persistent activation of STAT3 in epithelial/tumor cells in inflammation-associated colorectal cancer (CRC) is associated with sphingosine-1-phosphate (S1P) receptor signaling. In inflammatory response whereby interleukin (IL)-6 production is abundant, STAT3-mediated pathways were found to promote the activation of sphingosine kinases (SphK1 and SphK2) leading to the production of S1P. Reciprocally, S1P encourages the activation of STAT3 through a positive autocrine-loop signaling. The crosstalk between IL-6, STAT3 and sphingolipid regulated pathways may play an essential role in tumorigenesis and tumor progression in inflamed intestines. Therapeutics targeting both STAT3 and sphingolipid are therefore likely to contribute novel and more effective therapeutic strategies against inflammation-associated CRC. PMID:25132744

  10. Icaritin Shows Potent Anti-Leukemia Activity on Chronic Myeloid Leukemia In Vitro and In Vivo by Regulating MAPK/ERK/JNK and JAK2/STAT3 /AKT Signalings

    PubMed Central

    Zhang, Guang sen; Meng, Kun; Kuang, Wen yong; Li, Jin; Zhou, Xin fu; Li, Rui juan; Peng, Hong ling; Dai, Chong wen; Shen, Jian Kai; Gong, Fan jie; Xu, Yun xiao; Liu, Su fang

    2011-01-01

    Purpose To explore the effects of Icaritin on chronic myeloid leukemia (CML) cells and underlying mechanisms. Method CML cells were incubated with various concentration of Icaritin for 48 hours, the cell proliferation was analyzed by MTT and the apoptosis was assessed with Annexin V and Hoechst 33258 staining. Cell hemoglobinization was determined. Western blotting was used to evaluate the expressions of MAPK/ERK/JNK signal pathway and Jak-2/Phorpho-Stat3/Phorsph-Akt network-related protein. NOD-SCID nude mice were applied to demonstrate the anti-leukemia effect of Icaritin in vivo. Results Icaritin potently inhibited proliferation of K562 cells (IC50 was 8 µM) and primary CML cells (IC50 was 13.4 µM for CML-CP and 18 µM for CML-BC), induced CML cells apoptosis and promoted the erythroid differentiation of K562 cells with time-dependent manner. Furthermore, Icaritin was able to suppress the growth of primary CD34+ leukemia cells (CML) and Imatinib-resistant cells, and to induce apoptosis. In mouse leukemia model, Icaritin could prolong lifespan of NOD-SCID nude mice inoculated with K562 cells as effective as Imatinib without suppression of bone marrow. Icaritin could up-regulate phospho-JNK or phospho-C-Jun and down-regulate phospho-ERK, phospho-P-38, Jak-2, phospho-Stat3 and phospho-Akt expression with dose- or time-dependent manner. Icaritin had no influence both on c-Abl and phospho-c-Abl protein expression and mRNA levels of Bcr/Abl. Conclusion Icaritin from Chinese herb medicine may be a potential anti-CML agent with low adverse effect. The mechanism of anti-leukemia for Icaritin is involved in the regulation of Bcr/Abl downstream signaling. Icaritin may be useful for an alternative therapeutic choice of Imatinib-resistant forms of CML. PMID:21887305

  11. Nuclear protein I{kappa}B-{zeta} inhibits the activity of STAT3

    SciTech Connect

    Wu, Zhihao; Zhang, Xiaoai; Yang, Juntao; Wu, Guangzhou; Zhang, Ying; Yuan, Yanzhi; Jin, Chaozhi [State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850 (China)] [State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850 (China); Chang, Zhijie [Department of Biological Sciences and Biotechnology, Institute of Biomedicine, Tsinghua University, Beijing 100084 (China)] [Department of Biological Sciences and Biotechnology, Institute of Biomedicine, Tsinghua University, Beijing 100084 (China); Wang, Jian, E-mail: wangjian@nic.bmi.ac.cn [State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850 (China)] [State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850 (China); Yang, Xiaoming, E-mail: xmyang2@nic.bmi.ac.cn [State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850 (China)] [State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850 (China); He, Fuchu, E-mail: hefc@nic.bmi.ac.cn [State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850 (China) [State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850 (China); Institutes of Biomedical Sciences, Fudan University, Shanghai 200032 (China)

    2009-09-18

    STAT3 (Signal transducer and activator of transcription 3) is a key transcription factor of the JAK-STAT (Janus kinase/signal transducer and activator of transcription) pathway that regulates cell proliferation and apoptosis. Activation of STAT3 is under tight regulation, and yet the different signaling pathways and the mechanisms that regulate its activity remain to be elucidated. Using a yeast two-hybrid screening, we have identified a nuclear protein I{kappa}B-{zeta} that interacts in a novel way with STAT3. This physical interaction was further confirmed by co-immunoprecipitation assays. The interaction regions were mapped to the coiled-coil domain of STAT3 and the C-terminal of I{kappa}B-{zeta}. Overexpression of I{kappa}B-{zeta} inhibited the transcriptional activity of STAT3. It also suppressed cell growth and induced cell apoptosis in SRC-simulated cells, which is partially mediated by down-regulation of expression of a known STAT3 target gene, MCL1. Our results suggest that I{kappa}B-{zeta} is a negative regulator of STAT3, and demonstrate a novel mechanism in which a component of the NF-{kappa}B signaling pathway inhibits the activation of STAT3.

  12. Epstein–Barr virus nuclear antigen leader protein localizes to promoters and enhancers with cell transcription factors and EBNA2

    PubMed Central

    Portal, Daniel; Zhou, Hufeng; Zhao, Bo; Kharchenko, Peter V.; Lowry, Elizabeth; Wong, Limsoon; Quackenbush, John; Holloway, Dustin; Jiang, Sizun; Lu, Yong; Kieff, Elliott

    2013-01-01

    Epstein–Barr virus (EBV) nuclear antigens EBNALP (LP) and EBNA2 (E2) are coexpressed in EBV-infected B lymphocytes and are critical for lymphoblastoid cell line outgrowth. LP removes NCOR and RBPJ repressive complexes from promoters, enhancers, and matrix-associated deacetylase bodies, whereas E2 activates transcription from distal enhancers. LP ChIP-seq analyses identified 19,224 LP sites of which ?50% were ±2 kb of a transcriptional start site. LP sites were enriched for B-cell transcription factors (TFs), YY1, SP1, PAX5, BATF, IRF4, ETS1, RAD21, PU.1, CTCF, RBPJ, ZNF143, SMC3, NF?B, TBLR, and EBF. E2 sites were also highly enriched for LP-associated cell TFs and were more highly occupied by RBPJ and EBF. LP sites were highly marked by H3K4me3, H3K27ac, H2Az, H3K9ac, RNAPII, and P300, indicative of activated transcription. LP sites were 29% colocalized with E2 (LP/E2). LP/E2 sites were more similar to LP than to E2 sites in associated cell TFs, RNAPII, P300, and histone H3K4me3, H3K9ac, H3K27ac, and H2Az occupancy, and were more highly transcribed than LP or E2 sites. Gene affected by CTCF and LP cooccupancy were more highly expressed than genes affected by CTCF alone. LP was at myc enhancers and promoters and of MYC regulated ccnd2, 23 med complex components, and MYC regulated cell survival genes, igf2r and bcl2. These data implicate LP and associated TFs and DNA looping factors CTCF, RAD21, SMC3, and YY1/INO80 chromatin-remodeling complexes in repressor depletion and gene activation necessary for lymphoblastoid cell line growth and survival. PMID:24167291

  13. Lung Adenocarcinomas and Lung Cancer Cell Lines Show Association of MMP-1 Expression With STAT3 Activation1

    PubMed Central

    Schütz, Alexander; Röser, Katrin; Klitzsch, Jana; Lieder, Franziska; Aberger, Fritz; Gruber, Wolfgang; Mueller, Kristina M.; Pupyshev, Alexander; Moriggl, Richard; Friedrich, Karlheinz

    2015-01-01

    Signal transducer and activator of transcription 3 (STAT3) is constitutively activated in the majority of lung cancer. This study aims at defining connections between STAT3 function and the malignant properties of non–small cell lung carcinoma (NSCLC) cells. To address possible mechanisms by which STAT3 influences invasiveness, the expression of matrix metalloproteinase-1 (MMP-1) was analyzed and correlated with the STAT3 activity status. Studies on both surgical biopsies and on lung cancer cell lines revealed a coincidence of STAT3 activation and strong expression of MMP-1. MMP-1 and tyrosine-phosphorylated activated STAT3 were found co-localized in cancer tissues, most pronounced in tumor fronts, and in particular in adenocarcinomas. STAT3 activity was constitutive, although to different degrees, in the lung cancer cell lines investigated. Three cell lines (BEN, KNS62, and A549) were identified in which STAT3 activitation was inducible by Interleukin-6 (IL-6). In A549 cells, STAT3 activity enhanced the level of MMP-1 mRNA and stimulated transcription from the MMP-1 promoter in IL-6–stimulated A549 cells. STAT3 specificity of this effect was confirmed by STAT3 knockdown through RNA interference. Our results link aberrant activity of STAT3 in lung cancer cells to malignant tumor progression through up-regulation of expression of invasiveness-associated MMPs. PMID:25926075

  14. Cucurbitacin B and cucurbitacin I suppress adipocyte differentiation through inhibition of STAT3 signaling.

    PubMed

    Seo, Cho-Rong; Yang, Dong Kwon; Song, No-Joon; Yun, Ui Jeong; Gwon, A-Ryeong; Jo, Dong-Gyu; Cho, Jae Youl; Yoon, Keejung; Ahn, Jee-Yin; Nho, Chu Won; Park, Woo Jin; Yang, Seung Yul; Park, Kye Won

    2014-02-01

    Cucurbitacin B, a member of the cucurbitaceae family, can act as a STAT3 signaling inhibitor to regulate the growth of hepatocellular carcinoma. STAT3 signaling has been shown to inhibit adipocyte differentiation through C/EBP? and PPAR?. Based on these studies, we hypothesized that cucurbitacin B would prevent PPAR? mediated adipocyte differentiation through STAT3 signaling. To test this hypothesis, mesenchymal C3H10T1/2 and 3T3-L1 preadipocyte cells were treated with a sub-cytotoxic concentration of cucurbitacin B. Cucurbitacin B treatment inhibits lipid accumulation and expression of adipocyte markers including PPAR? and its target genes in a dose-dependent manner. Cucurbitacin B treatment impairs STAT3 signaling as manifested by reduced phosphorylation of STAT3 and suppression of STAT3 target gene expression in preadipocytes. The anti-adipogenic effects of cucurbitacin B are significantly blunted in cells with STAT3 silenced by introducing small interfering RNA. Finally, our data show that cucurbitacin I, another cucurbitacin family member, also inhibits adipocyte differentiation by suppressing STAT3 signaling. Together, our data suggest the possibility of utilizing cucurbitacins as a new strategy to treat metabolic diseases and implicate STAT3 as a new target for the development of functional foods and drugs. PMID:24316209

  15. The involvement of JAK-STAT3 in cell motility, invasion, and metastasis

    PubMed Central

    Teng, Yong; Ross, James L; Cowell, John K

    2014-01-01

    JAK-STAT3 signaling, while regulating many aspects of cancer development and progression, promotes invasion and metastasis through activation of key metastasis promoting genes such as WASF3. STAT3 promotes WASF3 expression and JAK2 independently activates it, which is required for invasion. JAK-STAT3 signaling is dependent on WASF3 function, since its inactivation in cells expressing JAK-STAT3 suppresses invasion. WASF3 overexpression leads to activation of NF?B and ZEB1 which also promote invasion through regulation of target genes involved in metastasis. NF?B frequently cooperates with STAT3 to upregulate metastasis promoting genes such as matrix metalloproteinases and cytokines, as well as to suppress microRNAs which can suppresses invasion. This better understanding of the complex role played by JAK-STAT3 in the regulation of cell movement, invasion, and metastasis provides opportunities to suppress this lethal aspect of cancer progression by not only targeting the JAK and STAT3 proteins directly, but also some of the downstream effectors of JAK-STAT3 signaling. PMID:24778926

  16. STAT3 Revs Up the Powerhouse

    NSDL National Science Digital Library

    Nancy C. Reich (Stony Brook University; Molecular Genetics and Microbiology REV)

    2009-09-29

    Tyrosine phosphorylation of signal transducers and activators of transcription (STATs) promotes their dimerization and ability to bind target genes in the nucleus. However, evidence shows that one member of the STAT family, STAT3, has an additional property independent of its classical role in the nucleus. STAT3 modifed by serine phosphorylation augmented oxidative phosphorylation in mitochondria and supported cellular transformation by oncogenic Ras.

  17. STAT3 Activation Promotes Oncolytic HSV1 Replication in Glioma Cells

    PubMed Central

    Okemoto, Kazuo; Wagner, Benjamin; Meisen, Hans; Haseley, Amy; Kaur, Balveen; Chiocca, Ennio Antonio

    2013-01-01

    Recent studies report that STAT3 signaling is a master regulator of mesenchymal transformation of gliomas and that STAT3 modulated genes are highly expressed in the mesenchymal transcriptome of gliomas. A currently studied experimental treatment for gliomas consists of intratumoral injection of oncolytic viruses (OV), such as oncolytic herpes simplex virus type 1 (oHSV). We have described one particular oHSV (rQNestin34.5) that exhibits potent anti-glioma activity in animal models. Here, we hypothesized that alterations in STAT3 signaling in glioma cells may affect the replicative ability of rQNestin34.5. In fact, human U251 glioma cells engineered to either over-express STAT3 or with genetic down-regulation of STAT3 supported oHSV replication to a significantly higher or lesser degree, respectively, when compared to controls. Administration of pharmacologic agents that increase STAT3 phosphorylation/activation (Valproic Acid) or increase STAT3 levels (Interleukin 6) also significantly enhanced oHSV replication. Instead, administration of inhibitors of STAT3 phosphorylation/activation (LLL12) significantly reduced oHSV replication. STAT3 led to a reduction in interferon signaling in oHSV infected cells and inhibition of interferon signaling abolished the effect of STAT3 on oHSV replication. These data thus indicate that STAT3 signaling in malignant gliomas enhances oHSV replication, likely by inhibiting the interferon response in infected glioma cells, thus suggesting avenues for possible potentiation of oncolytic virotherapy. PMID:23936533

  18. Downregulation of STAT3 signaling induces apoptosis but also promotes anti-apoptotic gene expression in human pancreatic cancer cell lines

    Microsoft Academic Search

    Wolfgang Glienke; Eva Hausmann; Lothar Bergmann

    2011-01-01

    Signal transducer and activator of transcription 3 (STAT3) is a key regulator of cytokine signaling pathways that regulates\\u000a gene expression. In pancreatic cancer, constitutive activation of STAT3 contributes to oncogenesis by preventing apoptosis\\u000a through upregulation of anti-apoptotic proteins. We have examined the inhibition of STAT3 as a potential therapeutic approach\\u000a in pancreatic cancer. siRNA targeting STAT3 was used to evaluate

  19. Assessing the Role of STAT3 in DC Differentiation and Autologous DC Immunotherapy in Mouse Models of GBM

    PubMed Central

    Assi, Hikmat; Espinosa, Jaclyn; Suprise, Sarah; Sofroniew, Michael; Doherty, Robert; Zamler, Daniel; Lowenstein, Pedro R.; Castro, Maria G.

    2014-01-01

    Cellular microenvironments, particularly those found in tumors, elicit a tolerogenic DC phenotype which can attenuate immune responses. Central to this process is the STAT3-mediated signaling cascade. As a transcription factor and oncogene, STAT3 promotes the expression of genes which allow tumor cells to proliferate, migrate and evade apoptosis. More importantly, activation of STAT3 in tumor infiltrating immune cells has been shown to be responsible, in part, for their immune-suppressed phenotype. The ability of STAT3 to orchestrate a diverse set of immunosuppressive instructions has made it an attractive target for cancer vaccines. Using a conditional hematopoietic knockout mouse model of STAT3, we evaluated the impact of STAT3 gene ablation on the differentiation of dendritic cells from bone marrow precursors. We also assessed the impact of STAT3 deletion on phagocytosis, maturation, cytokine secretion and antigen presentation by GM-CSF derived DCs in vitro. In addition to in vitro studies, we compared the therapeutic efficacy of DC vaccination using STAT3 deficient DCs to wild type counterparts in an intracranial mouse model of GBM. Our results indicated the following pleiotropic functions of STAT3: hematopoietic cells which lacked STAT3 were unresponsive to Flt3L and failed to differentiate as DCs. In contrast, STAT3 was not required for GM-CSF induced DC differentiation as both wild type and STAT3 null bone marrow cells gave rise to similar number of DCs. STAT3 also appeared to regulate the response of GM-CSF derived DCs to CpG. STAT3 null DCs expressed high levels of MHC-II, secreted more IL-12p70, IL-10, and TNF? were better antigen presenters in vitro. Although STAT3 deficient DCs displayed an enhanced activated phenotype in culture, they elicited comparable therapeutic efficacy in vivo compared to their wild type counterparts when utilized in vaccination paradigms in mice bearing intracranial glioma tumors. PMID:24806510

  20. STAT3 Inhibitors: Finding a Home in Lymphoma and Leukemia

    PubMed Central

    Munoz, Javier; Dhillon, Navjot; Janku, Filip; Watowich, Stephanie S.

    2014-01-01

    The Janus kinase (JAK) and signal transducer and activator of transcription (STAT) pathway is an active mediator of cytokine signaling in the pathogenesis of solid and hematologic malignancies. The seven-member STAT family is composed of latent cytoplasmic transcription factors that are activated by phosphorylation intertwined in a network with activation that ultimately leads to cell proliferation. An activated kinase enzyme phosphorylates one STAT factor or more, which shuttle to the nucleus to regulate gene expression, promoting cell survival. Somatic STAT3 mutations have been recently reported in large granular lymphocytic leukemia, aplastic anemia, and myelodysplastic syndrome. Furthermore, the relationship between BCL6 and STAT3 in diffuse large B-cell lymphomas, particularly on the activated B-cell subtype, needs to be further explored. The search for therapeutic STAT3 inhibitors that abrogate the JAK/STAT pathway is currently under way. Targeting the STAT pathway, which seems to be critical in tumorigenesis, is promising for multiple malignancies including lymphoma and leukemia. In this paper, we review mechanisms of action, failures, and successes of STAT3 inhibitors. PMID:24705981

  1. Stat3-Efemp2a modulates the fibrillar matrix for cohesive movement of prechordal plate progenitors.

    PubMed

    Zhang, Ting; Yin, Chaoran; Qiao, Liangjun; Jing, Lulu; Li, Hongda; Xiao, Chun; Luo, Ning; Lei, Song; Meng, Wentong; Zhu, Hongyan; Liu, Jin; Xu, Hong; Mo, Xianming

    2014-11-01

    Recently, emerging evidence has shown that Stat3 controls tumor cell migration and invasion. However, the molecular mechanisms by which Stat3 controls the cell movement remain largely unknown. Embryonic gastrula progenitors display coordinated and orientated migration, called collective cell migration. Collective cell migration is the simultaneous movement of multiple cells and is universally involved in physiological and pathological programs. Stat3 activity is required for the migration of gastrula progenitors, but it does not affect cell specification, thus suggesting that gastrula movements are an excellent model to provide insight into Stat3 control of cell migration in vivo. In this study, we reveal a novel mechanism by which Stat3 modulates extracellular matrix (ECM) assembly to control the coherence of collective migration of prechordal plate progenitors during zebrafish embryonic gastrulation. We show that Stat3 regulates the expression of Efemp2a in the prechordal plate progenitors that migrate anteriorly during gastrulation. Alteration of Stat3-Efemp2a signaling activity disrupted the configuration of fibronectin (FN) and laminin (LM) matrices, resulting in defective coherence of prechordal plate progenitor movements in zebrafish embryos. We demonstrate that Efemp2a acts as a downstream effector of Stat3 to promote ECM configuration for coherent collective cell migrations in vivo. PMID:25371367

  2. Disruption of Astrocyte STAT3 Signaling Decreases Mitochondrial Function and Increases Oxidative Stress In Vitro

    PubMed Central

    Sarafian, Theodore A.; Montes, Cindy; Imura, Tetsuya; Qi, Jingwei; Coppola, Giovanni; Geschwind, Daniel H.; Sofroniew, Michael V.

    2010-01-01

    Background Astrocytes exert a wide variety of functions in health and disease and respond to a wide range of signaling pathways, including members of the Janus-kinase signal transducers and activators of transcription (Jak-STAT) family. We have recently shown that STAT3 is an important regulator of astrocyte reactivity after spinal cord injury in vivo [1]. Methodology/Principal Findings Here, we used both a conditional gene deletion strategy that targets the deletion of STAT3 selectively to astrocytes (STAT3-CKO), and a pharmacological inhibitor of JAK-2, AG490, in cultured astrocytes in vitro, to investigate potential functions and molecules influenced by STAT3 signaling in relation to mitochondrial function and oxidative stress. Our findings show that the absence of STAT3 signaling in astrocytes leads to (i) increased production of superoxide anion and other reactive oxygen species and decreased level of glutathione, (ii) decreased mitochondrial membrane potential and decreased ATP production, and (iii) decreased rate of cell proliferation. Many of the differences observed in STAT3-CKO astrocytes were distinctly altered by exposure to rotenone, suggesting a role for complex I of the mitochondrial electron transport chain. Gene expression microarray studies identified numerous changes in STAT3-CKO cells that may have contributed to the identified deficits in cell function. Conclusions/Significance Taken together, these STAT3-dependent alterations in cell function and gene expression have relevance to both reactive gliosis and to the support and protection of surrounding cells in neural tissue. PMID:20224768

  3. Essential role of IL-10/STAT3 in chronic stress-induced immune suppression

    PubMed Central

    Hu, Dan; Wan, Lei; Chen, Michael; Caudle, Yi; LeSage, Gene; Li, Qinchuan; Yin, Deling

    2013-01-01

    Stress can either enhance or suppress immune functions depending on a variety of factors such as duration of stressful condition. Chronic stress has been demonstrated to exert a significant suppressive effect on immune function. However, the mechanisms responsible for this phenomenon remain to be elucidated. Here, male C57BL/6 mice were placed in a 50-ml conical centrifuge tube with multiple punctures to establish a chronic restraint stress model. Serum IL-10 levels, IL-10 production by the splenocytes, and activation of STAT3 in the mouse spleen were assessed. We demonstrate that IL-10/STAT3 axis was remarkably activated following chronic stress. Moreover, TLR4 and p38 MAPK play a pivotal role in the activation of IL-10/STAT3 signaling cascade. Interestingly, blocking antibody against IL-10 receptor and inhibition of STAT3 by STAT3 inhibitor S3I-201 attenuates stress-induced lymphocyte apoptosis. Inhibition of IL-10/STAT3 dramatically inhibits stress-induced reduction in IL-12 production. Furthermore, disequilibrium of Th1/Th2 cytokine balance caused by chronic stress was also rescued by blocking IL-10/STAT3 axis. These results yield insight into a new mechanism by which chronic stress regulates immune functions. IL-10/STAT3 pathway provides a novel relevant target for the manipulation of chronic stress-induced immune suppression. PMID:24513872

  4. The Multifaceted Roles of STAT3 Signaling in the Progression of Prostate Cancer

    PubMed Central

    Bishop, Jennifer L.; Thaper, Daksh; Zoubeidi, Amina

    2014-01-01

    The signal transducer and activator of transcription (STAT)3 governs essential functions of epithelial and hematopoietic cells that are often dysregulated in cancer. While the role for STAT3 in promoting the progression of many solid and hematopoietic malignancies is well established, this review will focus on the importance of STAT3 in prostate cancer progression to the incurable metastatic castration-resistant prostate cancer (mCRPC). Indeed, STAT3 integrates different signaling pathways involved in the reactivation of androgen receptor pathway, stem like cells and the epithelial to mesenchymal transition that drive progression to mCRPC. As equally important, STAT3 regulates interactions between tumor cells and the microenvironment as well as immune cell activation. This makes it a major factor in facilitating prostate cancer escape from detection of the immune response, promoting an immunosuppressive environment that allows growth and metastasis. Based on the multifaceted nature of STAT3 signaling in the progression to mCRPC, the promise of STAT3 as a therapeutic target to prevent prostate cancer progression and the variety of STAT3 inhibitors used in cancer therapies is discussed. PMID:24722453

  5. Activated Rac1 requires gp130 for Stat3 activation, cell proliferation and migration

    SciTech Connect

    Arulanandam, Rozanne; Geletu, Mulu [Departments of Microbiology and Immunology and Pathology and Molecular Medicine, and Queen's University Cancer Institute, Queen's University, Botterell Hall, Rm. 713, Kingston, Ontario, Canada K7L 3N6 (Canada)] [Departments of Microbiology and Immunology and Pathology and Molecular Medicine, and Queen's University Cancer Institute, Queen's University, Botterell Hall, Rm. 713, Kingston, Ontario, Canada K7L 3N6 (Canada); Feracci, Helene [Universite Bordeaux 1, Centre de Recherche Paul Pascal, CNRS UPR 8641, 33600 Pessac (France)] [Universite Bordeaux 1, Centre de Recherche Paul Pascal, CNRS UPR 8641, 33600 Pessac (France); Raptis, Leda, E-mail: raptisl@queensu.ca [Departments of Microbiology and Immunology and Pathology and Molecular Medicine, and Queen's University Cancer Institute, Queen's University, Botterell Hall, Rm. 713, Kingston, Ontario, Canada K7L 3N6 (Canada)] [Departments of Microbiology and Immunology and Pathology and Molecular Medicine, and Queen's University Cancer Institute, Queen's University, Botterell Hall, Rm. 713, Kingston, Ontario, Canada K7L 3N6 (Canada)

    2010-03-10

    Rac1 (Rac) is a member of the Rho family of small GTPases which controls cell migration by regulating the organization of actin filaments. Previous results suggested that mutationally activated forms of the Rho GTPases can activate the Signal Transducer and Activator of Transcription-3 (Stat3), but the exact mechanism is a matter of controversy. We recently demonstrated that Stat3 activity of cultured cells increases dramatically following E-cadherin engagement. To better understand this pathway, we now compared Stat3 activity levels in mouse HC11 cells before and after expression of the mutationally activated Rac1 (Rac{sup V12}), at different cell densities. The results revealed for the first time a dramatic increase in protein levels and activity of both the endogenous Rac and Rac{sup V12} with cell density, which was due to inhibition of proteasomal degradation. In addition, Rac{sup V12}-expressing cells had higher Stat3, tyrosine-705 phosphorylation and activity levels at all densities, indicating that Rac{sup V12} is able to activate Stat3. Further examination of the mechanism of Stat3 activation showed that Rac{sup V12} expression caused a surge in mRNA of Interleukin-6 (IL6) family cytokines, known potent Stat3 activators. Knockdown of gp130, the common subunit of this family reduced Stat3 activity, indicating that these cytokines may be responsible for the Stat3 activation by Rac{sup V12}. The upregulation of IL6 family cytokines was required for cell migration and proliferation induced by Rac{sup V12}, as shown by gp130 knockdown experiments, thus demonstrating that the gp130/Stat3 axis represents an essential effector of activated Rac for the regulation of key cellular functions.

  6. Dangerous liaisons: STAT3 and NF-kappaB collaboration and crosstalk in cancer.

    PubMed

    Grivennikov, Sergei I; Karin, Michael

    2010-02-01

    Transcriptional factors of the NF-kappaB family and STAT3 are ubiquitously expressed and control numerous physiological processes including development, differentiation, immunity, metabolism and cancer. Both NF-kappaB and STAT3 are rapidly activated in response to various stimuli including stresses and cytokines, although they are regulated by entirely different signaling mechanisms. Once activated, NF-kappaB and STAT3 control the expression of anti-apoptotic, pro-proliferative and immune response genes. Some of these genes overlap and require transcriptional cooperation between the two factors. The activation of and interaction between STAT3 and NF-kappaB plays a key role in controlling the dialog between the malignant cell and its microenvironment, especially with inflammatory/immune cells that infiltrate tumors. Quite often, cytokines whose expression is induced in response to NF-kappaB in immune cells of the tumor microenvironment lead to STAT3 activation in both malignant and immune cells. While within malignant and pre-malignant cells STAT3 exerts important oncogenic functions, within inflammatory cells it may also suppress tumor promotion through its anti-inflammatory effects. Other interactions and forms of crosstalk between NF-kappaB and STAT3 include physical interaction between the two, cooperation of these factors at gene promoters/enhancers, the NF-kappaB dependent expression of inhibitors of STAT3 activation and the participation of STAT3 in inflammatory cells in the negative regulation NF-kappaB. Despite these versatile and occasionally antagonistic interactions, NF-kappaB and STAT3 cooperate to promote the development and progression of colon, gastric and liver cancers. In addition to explaining the molecular pathogenesis of cancer, these interactions also offer opportunities for the design of new therapeutic interventions. PMID:20018552

  7. SirT1 and STAT3 protect retinal pigmented epithelium cells against oxidative stress.

    PubMed

    Li, Langen; Wei, Wei; Zhang, Yufeng; Tu, Gerile; Zhang, Yanmei; Yang, Jia; Xing, Yiqiao

    2015-08-01

    It has been previously demonstrated that there are interactions between sirtuin 1 (SirT1) and signal transducer and activator of transcription 3 (STAT3), which have versatile roles in various microenvironments. However, whether or not there is crosstalk between these two molecules during oxidative stress, and what mechanism of crosstalk occurs in retinal pigmented epithelium cells (RPEs), the protection of which may delay the process of age?related macular degeneration (AMD), has required further elucidation. The present study aimed to investigate the interactions between SirT1 and STAT3 in RPEs, following exposure to oxidative stress. The rates of proliferation and apoptosis, levels of intracellular reactive oxygen species and cell senescence of RPEs, induced by oxidants [H2O2 and oxidized low density lipoprotein (oxLDL)], were evaluated. The results revealed a downregulation of SirT1 expression, and an upregulation of STAT3 expression during oxidative stress. Further investigation indicated that SirT1 protected RPEs from oxidative stress?induced damage. Furthermore, gain? and loss?of?function experiments indicated that SirT1 had negative effects on the regulation of STAT3 expression in RPEs during oxidative stress. Notably, STAT3 directly protected the cells from oxidative stress, rather than depending on SirT1. Additionally, the protective effects of STAT3 had no association with the modulation of cell senescence during oxidative stress. In conclusion, SirT1 had negative effects on the regulation of STAT3 expression during oxidative stress. However, SirT1 and STAT3 demonstrated protective roles against oxidative stress in RPEs. These results therefore suggested that there was an equilibrium mechanism between SirT1 and STAT3 against oxidative stress, meaning that an equilibrium mechanism is required to be considered when combined application of STAT3 and SirT1 were performed to treat AMD. PMID:25847123

  8. Emodin inhibits growth and induces apoptosis in an orthotopic hepatocellular carcinoma model by blocking activation of STAT3

    PubMed Central

    Subramaniam, Aruljothi; Shanmugam, Muthu K; Ong, Tina H; Li, Feng; Perumal, Ekambaram; Chen, Luxi; Vali, Shireen; Abbasi, Taher; Kapoor, Shweta; Ahn, Kwang Seok; Kumar, Alan Prem; Hui, Kam M; Sethi, Gautam

    2013-01-01

    BACKGROUND AND PURPOSE Aberrant activation of STAT3 is frequently encountered and promotes proliferation, survival, metastasis and angiogenesis in hepatocellular carcinoma (HCC). Here, we have investigated whether emodin mediates its effect through interference with the STAT3 activation pathway in HCC. EXPERIMENTAL APPROACH The effect of emodin on STAT3 activation, associated protein kinases and apoptosis was investigated using various HCC cell lines. Additionally, we also used a predictive tumour technology to analyse the effects of emodin. The in vivo effects of emodin were assessed in an orthotopic mouse model of HCC. KEY RESULTS Emodin suppressed STAT3 activation in a dose- and time-dependent manner in HCC cells, mediated by the modulation of activation of upstream kinases c-Src, JAK1 and JAK2. Vanadate treatment reversed emodin-induced down-regulation of STAT3, suggesting the involvement of a tyrosine phosphatase and emodin induced the expression of the tyrosine phosphatase SHP-1 that correlated with the down-regulation of constitutive STAT3 activation. Interestingly, silencing of the SHP-1 gene by siRNA abolished the ability of emodin to inhibit STAT3 activation. Finally, when administered i.p., emodin inhibited the growth of human HCC orthotopic tumours in male athymic nu/nu mice and STAT3 activation in tumour tissues. CONCLUSIONS AND IMPLICATIONS Emodin mediated its effects predominantly through inhibition of the STAT3 signalling cascade and thus has a particular potential for the treatment of cancers expressing constitutively activated STAT3. PMID:23848338

  9. STAT3 signaling controls satellite cell expansion and skeletal muscle repair

    PubMed Central

    Tierney, Matthew Timothy; Aydogdu, Tufan; Sala, David; Malecova, Barbora; Gatto, Sole; Puri, Pier Lorenzo; Latella, Lucia; Sacco, Alessandra

    2015-01-01

    The progression of disease- and age-dependent skeletal muscle wasting results in part from a decline in the number and function of satellite cells, the direct cellular contributors to muscle repair1–10. However, little is known about the molecular effectors underlying satellite cell impairment and depletion. Elevated levels of inflammatory cytokines, including interleukin-6 (IL-6), are associated with both age-related and muscle-wasting conditions11–13. The levels of STAT3, a downstream effector of IL-6, are also elevated with muscle wasting14,15, and STAT3 has been implicated in the regulation of self-renewal and stem cell fate in several tissues16–19. Here we show that IL-6–activated Stat3 signaling regulates satellite cell behavior, promoting myogenic lineage progression through myogenic differentiation 1 (Myod1) regulation. Conditional ablation of Stat3 in Pax7-expressing satellite cells resulted in their increased expansion during regeneration, but compromised myogenic differentiation prevented the contribution of these cells to regenerating myofibers. In contrast, transient Stat3 inhibition promoted satellite cell expansion and enhanced tissue repair in both aged and dystrophic muscle. The effects of STAT3 inhibition were conserved in human myoblasts. The results of this study indicate that pharmacological manipulation of STAT3 activity can be used to counteract the functional exhaustion of satellite cells, thereby maintaining the endogenous regenerative response and ameliorating muscle-wasting diseases. PMID:25194572

  10. Effects of JAK2-STAT3 signaling after cerebral insults

    PubMed Central

    Raible, Daniel J; Frey, Lauren C; Brooks-Kayal, Amy R

    2014-01-01

    The JAK2-STAT3 signaling pathway has been shown to regulate the expression of genes involved in cell survival, cell proliferation, cell-cycle progression, and angiogenesis in development and after cerebral insults. Until recently, little has been known about the effects of this pathway activation after cerebral insults and if blocking this pathway leads to better recovery. This review exams the role of this pathway after 3 cerebral insults (traumatic brain injury, stroke, and status epilepticus). PMID:25105066

  11. NF-?B, p38 MAPK, ERK1/2, mTOR, STAT3 and increased glycolysis regulate stability of paricalcitol/dexamethasone-generated tolerogenic dendritic cells in the inflammatory environment.

    PubMed

    Dá?ová, Klára; Klapetková, Anna; Kayserová, Jana; Šedivá, Anna; Špíšek, Radek; Jelínková, Lenka Palová

    2015-06-10

    Tolerogenic dendritic cells (tDCs) may offer an intervention therapy in autoimmune diseases or transplantation. Stable immaturity and tolerogenic function of tDCs after encountering inflammatory environment are prerequisite for positive outcome of immunotherapy. However, the signaling pathways regulating their stable tolerogenic properties are largely unknown. In this study, we demonstrated that human monocyte-derived tDCs established by using paricalcitol (analogue of vitamin D2), dexamethasone and monophosphoryl lipid A exposed for 24h to LPS, cytokine cocktail, polyI:C or CD40L preserved reduced expression of co-stimulatory molecules, increased levels of inhibitory molecules ILT-3, PDL-1 and TIM-3, increased TLR-2, increased secretion of IL-10 and TGF-?, reduced IL-12 and TNF-? secretion and reduced T cell stimulatory capacity. tDCs further induced IL-10-producing T regulatory cells that suppressed the proliferation of responder T cells. In the inflammatory environment, tDCs maintained up-regulated indoleamine 2, 3 dioxygenase but abrogated I?B-? phosphorylation and reduced transcriptional activity of p65/RelA, RelB and c-Rel NF-?B subunits except p50. Mechanistically, p38 MAPK, ERK1/2, mTOR, STAT3 and mTOR-dependent glycolysis regulated expression of ILT-3, PDL-1 and CD86, secretion of IL-10 and T cell stimulatory capacity of tDCs in the inflammatory environment. Stability of tDCs in the inflammatory environment is thus regulated by multiple signaling pathways. PMID:26053099

  12. Monocytes Induce STAT3 Activation in Human Mesenchymal Stem Cells to Promote Osteoblast Formation

    PubMed Central

    Nicolaidou, Vicky; Wong, Mei Mei; Redpath, Andia N.; Ersek, Adel; Baban, Dilair F.; Williams, Lynn M.; Cope, Andrew P.; Horwood, Nicole J.

    2012-01-01

    A major therapeutic challenge is how to replace bone once it is lost. Bone loss is a characteristic of chronic inflammatory and degenerative diseases such as rheumatoid arthritis and osteoporosis. Cells and cytokines of the immune system are known to regulate bone turnover by controlling the differentiation and activity of osteoclasts, the bone resorbing cells. However, less is known about the regulation of osteoblasts (OB), the bone forming cells. This study aimed to investigate whether immune cells also regulate OB differentiation. Using in vitro cell cultures of human bone marrow-derived mesenchymal stem cells (MSC), it was shown that monocytes/macrophages potently induced MSC differentiation into OBs. This was evident by increased alkaline phosphatase (ALP) after 7 days and the formation of mineralised bone nodules at 21 days. This monocyte-induced osteogenic effect was mediated by cell contact with MSCs leading to the production of soluble factor(s) by the monocytes. As a consequence of these interactions we observed a rapid activation of STAT3 in the MSCs. Gene profiling of STAT3 constitutively active (STAT3C) infected MSCs using Illumina whole human genome arrays showed that Runx2 and ALP were up-regulated whilst DKK1 was down-regulated in response to STAT3 signalling. STAT3C also led to the up-regulation of the oncostatin M (OSM) and LIF receptors. In the co-cultures, OSM that was produced by monocytes activated STAT3 in MSCs, and neutralising antibodies to OSM reduced ALP by 50%. These data indicate that OSM, in conjunction with other mediators, can drive MSC differentiation into OB. This study establishes a role for monocyte/macrophages as critical regulators of osteogenic differentiation via OSM production and the induction of STAT3 signalling in MSCs. Inducing the local activation of STAT3 in bone cells may be a valuable tool to increase bone formation in osteoporosis and arthritis, and in localised bone remodelling during fracture repair. PMID:22802946

  13. Revisiting STAT3 signalling in cancer: new and unexpected biological functions.

    PubMed

    Yu, Hua; Lee, Heehyoung; Herrmann, Andreas; Buettner, Ralf; Jove, Richard

    2014-11-01

    The Janus kinases (JAKs) and signal transducer and activator of transcription (STAT) proteins, particularly STAT3, are among the most promising new targets for cancer therapy. In addition to interleukin-6 (IL-6) and its family members, multiple pathways, including G-protein-coupled receptors (GPCRs), Toll-like receptors (TLRs) and microRNAs were recently identified to regulate JAK-STAT signalling in cancer. Well known for its role in tumour cell proliferation, survival, invasion and immunosuppression, JAK-STAT3 signalling also promotes cancer through inflammation, obesity, stem cells and the pre-metastatic niche. In addition to its established role as a transcription factor in cancer, STAT3 regulates mitochondrion functions, as well as gene expression through epigenetic mechanisms. Newly identified regulators and functions of JAK-STAT3 in tumours are important targets for potential therapeutic strategies in the treatment of cancer. PMID:25342631

  14. Involvement of STAT3 in bladder smooth muscle hypertrophy following bladder outlet obstruction.

    PubMed

    Fujita, Osamu; Asanuma, Masato; Yokoyama, Teruhiko; Miyazaki, Ikuko; Ogawa, Norio; Kumon, Hiromi

    2006-12-01

    We examined the involvement of the signal transducer and activator of transcription 3 (STAT3) in bladder outlet obstruction (BOO)-induced bladder smooth muscle hypertrophy using a rat in vivo and in vitro study. BOO induced increases in bladder weight and bladder smooth muscle thickness 1 week after the operation. By using antibody microarrays, 64 of 389 proteins blotted on the array met our selection criteria of an INR value between > or = 2.0 and < or = 0.5. This result revealed up-regulation of transcription factors, cell cycle regulatory proteins, apoptosis-associated proteins and so on. On the other hand, down-regulation (INR value < or = 0.5) of proteins was not found. In a profiling study, we found an increase in the expression of STAT3. A significant increase in nuclear phosphorylated STAT3 expression was confirmed in bladder smooth muscle tissue by immunohistochemistry and Western blot analysis. Cyclical stretch-relaxation (1 Hz) at 120% elongation significantly increased the expression of STAT3 and of alpha-smooth muscle actin in primary cultured bladder smooth muscle cells. Furthermore, the blockade of STAT3 expression by the transfection of STAT3 small interfering RNA (siRNA) significantly prevented the stretch-induced increase in alpha-smooth muscle actin expression. These results suggest that STAT3 has an important role in the induction of bladder smooth muscle hypertrophy. PMID:17189973

  15. Phosphorylation of STAT3 correlates with HER2 status, but not with survival in pancreatic ductal adenocarcinoma.

    PubMed

    Koperek, Oskar; Aumayr, Klaus; Schindl, Martin; Werba, Gregor; Soleiman, Afschin; Schoppmann, Sebastian; Sahora, Klaus; Birner, Peter

    2014-06-01

    Activation of signal-transcriptional factor signal transducer and activator of transcription 3 (STAT3) is associated with more aggressive behaviour in a variety of human malignancies. As selective STAT3 inhibitors exist, this protein might represent a novel therapeutic target. Although STAT3 seems to play an important role in progression of pancreatic ductal carcinoma (PDAC), only few data on this subject exist. The aim of our study was the investigation of STAT3 activation and its correlation with its possible regulator HER2. Expression of tyrosine-705 phosphorylated STAT3 (pSTAT3) was determined immunohistochemically in 79 PDACs. HER2 status assessed by immunohistochemistry and double colour silver in situ hybridization was available from a previous study. PSTAT3 expression was seen in 33 (41.8%) patients. Six patients were scored as HER2 positive having strong correlation with pSTAT3 expression (p = 0.004, Fisher's exact test). No association of pSTAT3 expression with patients' age, tumour staging and grading, perineural invasion of tumour cells or survival time was seen. pSTAT3 is frequently expressed in PDAC. Nevertheless, its immediate clinical relevance seems to be low. However, further research needs to determine whether STAT3 status in PDAC is predictive for the response to novel targeting therapies. PMID:24164699

  16. Stat3 Programs Th17-Specific Regulatory T Cells to Control GN

    PubMed Central

    Kluger, Malte A.; Luig, Michael; Wegscheid, Claudia; Goerke, Boeren; Paust, Hans-Joachim; Brix, Silke R.; Yan, Isabell; Mittrücker, Hans-Willi; Hagl, Beate; Renner, Ellen D.; Tiegs, Gisa; Wiech, Thorsten; Stahl, Rolf A.K.; Panzer, Ulf

    2014-01-01

    A pathogenic role for Th17 cells in inflammatory renal disease is well established. The mechanisms underlying their counter-regulation are, however, largely unknown. Recently, Th17 lineage-specific regulatory T cells (Treg17) that depend on activation of the transcription factor Stat3 were identified. We studied the function of Treg17 in the nephrotoxic nephritis (NTN) model of crescentic GN. The absence of Treg17 cells in Foxp3Cre×Stat3fl/fl mice resulted in the aggravation of NTN and skewing of renal and systemic immune responses toward Th17. Detailed analysis of Stat3-deficient Tregs revealed that the survival, activation, proliferation, and suppressive function of these cells remained intact. However, Tregs from Foxp3Cre×Stat3fl/fl mice lacked surface expression of the chemokine receptor CCR6, which resulted in impaired renal trafficking. Furthermore, aggravation of NTN was reversible in the absence of Th17 responses, as shown in CD4Cre×Stat3fl/fl mice lacking both Treg17 and Th17 cells, suggesting that Th17 cells are indeed the major target of Treg17 cells. Notably, immunohistochemistry revealed CCR6-bearing Treg17 cells in kidney biopsy specimens of patients with GN. CCR6 expression on human Treg17 cells also appears dependent on STAT3, as shown by analysis of Tregs from patients with dominant-negative STAT3 mutations. Our data indicate the presence and involvement of Stat3/STAT3-dependent Treg17 cells that specifically target Th17 cells in murine and human crescentic GN, and suggest the kidney-specific action of these Treg17 cells is regulated by CCR6-directed migration into areas of Th17 inflammation. PMID:24511136

  17. High-Content pSTAT3/1 Imaging Assays to Screen for Selective Inhibitors of STAT3 Pathway Activation in Head and Neck Cancer Cell Lines

    PubMed Central

    Sen, Malabika; Hua, Yun; Camarco, Daniel; Shun, Tong Ying; Lazo, John S.; Grandis, Jennifer R.

    2014-01-01

    Abstract The oncogenic transcription factor signal transducer and activator of transcription 3 (STAT3) is hyperactivated in most cancers and represents a plausible therapeutic target. In the absence of STAT3-selective small-molecule inhibitors, we sought to develop pSTAT3/1 high-content imaging (HCS) assays to screen for selective inhibitors of STAT3 pathway activation in head and neck squamous cell carcinomas (HNSCC) tumor cell lines. Based on the expression of the interleukin-6 (IL-6)R? and gp130 subunits of the IL-6 receptor complex and STAT3, we selected the Cal33 HNSCC cell line as our model. After developing image acquisition and analysis procedures, we rigorously investigated the cytokine activation responses to optimize the dynamic ranges of both assays and demonstrated that the pan-Janus kinase inhibitor pyridone 6 nonselectively inhibited pSTAT3 and pSTAT1 activation with 50% inhibition concentrations of 7.19±4.08 and 16.38±8.45?nM, respectively. The optimized pSTAT3 HCS assay performed very well in a pilot screen of 1,726 compounds from the Library of Pharmacologically Active Compounds and the National Institutes of Health clinical collection sets, and we identified 51 inhibitors of IL-6-induced pSTAT3 activation. However, only three of the primary HCS actives selectively inhibited STAT3 compared with STAT1. Our follow-up studies indicated that the nonselective inhibition of cytokine induced pSTAT3 and pSTAT1 activation by G-alpha stimulatory subunit-coupled G-protein-coupled receptor agonists, and forskolin was likely due to cyclic adenosine monophosphate-mediated up-regulation of suppressors of cytokine signaling 3. Azelastine, an H1 receptor antagonist approved for the treatment of seasonal allergic rhinitis, nonallergic vasomotor rhinitis, and ocular conjunctivitis, was subsequently confirmed as a selective inhibitor of IL-6-induced pSTAT3 activation that also reduced the growth of HNSCC cell lines. These data illustrate the power of a chemical biology approach to lead generation that utilizes fully developed and optimized HCS assays as phenotypic screens to interrogate specific signaling pathways. PMID:24127660

  18. Drug-repositioning screening identified piperlongumine as a direct STAT3 inhibitor with potent activity against breast cancer.

    PubMed

    Bharadwaj, U; Eckols, T K; Kolosov, M; Kasembeli, M M; Adam, A; Torres, D; Zhang, X; Dobrolecki, L E; Wei, W; Lewis, M T; Dave, B; Chang, J C; Landis, M D; Creighton, C J; Mancini, M A; Tweardy, D J

    2015-03-12

    Signal transducer and activator of transcription (STAT) 3 regulates many cardinal features of cancer including cancer cell growth, apoptosis resistance, DNA damage response, metastasis, immune escape, tumor angiogenesis, the Warburg effect and oncogene addiction and has been validated as a drug target for cancer therapy. Several strategies have been used to identify agents that target Stat3 in breast cancer but none has yet entered into clinical use. We used a high-throughput fluorescence microscopy search strategy to identify compounds in a drug-repositioning library (Prestwick library) that block ligand-induced nuclear translocation of Stat3 and identified piperlongumine (PL), a natural product isolated from the fruit of the pepper Piper longum. PL inhibited Stat3 nuclear translocation, inhibited ligand-induced and constitutive Stat3 phosphorylation, and modulated expression of multiple Stat3-regulated genes. Surface plasmon resonance assay revealed that PL directly inhibited binding of Stat3 to its phosphotyrosyl peptide ligand. Phosphoprotein antibody array analysis revealed that PL does not modulate kinases known to activate Stat3 such as Janus kinases, Src kinase family members or receptor tyrosine kinases. PL inhibited anchorage-independent and anchorage-dependent growth of multiple breast cancer cell lines having increased pStat3 or total Stat3, and induced apoptosis. PL also inhibited mammosphere formation by tumor cells from patient-derived xenografts. PL's antitumorigenic function was causally linked to its Stat3-inhibitory effect. PL was non-toxic in mice up to a dose of 30?mg/kg/day for 14 days and caused regression of breast cancer cell line xenografts in nude mice. Thus, PL represents a promising new agent for rapid entry into the clinic for use in treating breast cancer, as well as other cancers in which Stat3 has a role. PMID:24681959

  19. ?-Caryophyllene oxide inhibits constitutive and inducible STAT3 signaling pathway through induction of the SHP-1 protein tyrosine phosphatase.

    PubMed

    Kim, Chulwon; Cho, Somi K; Kapoor, Shweta; Kumar, Ansu; Vali, Shireen; Abbasi, Taher; Kim, Sung-Hoon; Sethi, Gautam; Ahn, Kwang Seok

    2014-10-01

    Constitutive activation of STAT3 is frequently observed and closely linked with proliferation, survival, invasion, metastasis and angiogenesis in tumor cells. In the present study, we investigated whether ?-caryophyllene oxide (CPO), a sesquiterpene isolated primarily from the essential oils of medicinal plants such as guava (Psidium guajava), and oregano (Origanum vulgare L.), can mediate its effect through interference with the STAT3 activation pathway in cancer cells. The effect of CPO on STAT3 activation, associated protein kinases and phosphatase, STAT3-regulated gene products and apoptosis was investigated using both functional proteomics tumor pathway technology platform and different tumor cell lines. We found that CPO suppressed constitutive STAT3 activation in multiple myeloma (MM), breast and prostate cancer cell lines, with a significant dose- and time-dependent effects observed in MM cells. The suppression was mediated through the inhibition of activation of upstream kinases c-Src and JAK1/2. Also, vanadate treatment reversed CPO-induced down-regulation of STAT3, suggesting the involvement of a tyrosine phosphatase. Indeed, we found that CPO induced the expression of tyrosine phosphatase SHP-1 that correlated with the down-regulation of constitutive STAT3 activation. Interestingly, deletion of SHP-1 gene by siRNA abolished the ability of CPO to inhibit STAT3 activation. The inhibition of STAT3 activation by CPO inhibited proliferation, induced apoptosis and abrogated the invasive potential of tumor cells. Our results suggest for the first time that CPO is a novel blocker of STAT3 signaling cascade and thus has an enormous potential for the treatment of various cancers harboring constitutively activated STAT3. PMID:23765383

  20. STAT3 in CD4+ T helper Cell differentiation and Inflammatory Diseases

    PubMed Central

    Egwuagu, Charles E.

    2009-01-01

    Jak/STAT pathways influence cell-fate decisions made by differentiating naïve T-cells, regulate the intensity and duration of inflammatory responses and are implicated in pathogenic mechanisms of a number of chronic inflammatory diseases. Among the STATs, the STAT3 protein has emerged as an important determinant of whether the naïve T cell differentiates into regulatory (Treg) or an inflammatory (Th17) T cell lineage. STAT3 also has potent anti-inflammatory effects and regulates critical cellular processes such as, cell growth, apoptosis and transcription of inflammatory genes. Dysregulation of STAT3 pathway has therefore been implicated in the development of chronic inflammatory diseases, as well as, a number of malignant and neurodegenerative diseases. This review focuses on recent findings regarding the role of STAT3 in immunity, with particular emphasis on T cell lineage specification and disease etiology. New insights from animal models of uveitis, multiple sclerosis and inflammatory bowel diseases are discussed as exemplars of critical roles that STAT3 pathways play in inflammatory diseases and on how inhibiting STAT3 can be exploited to mitigate pathogenic autoimmunity. PMID:19648026

  1. Development of a STAT3 reporter prostate cancer cell line for high throughput screening of STAT3 activators and inhibitors

    SciTech Connect

    Chau, My N. [Department of Biochemistry, Molecular and Cellular Biology, Georgetown University Medical Center, Medical-Dental Building, Room C406B, 3900 Reservoir Road, Northwest, Washington, DC 20057 (United States); Banerjee, Partha P. [Department of Biochemistry, Molecular and Cellular Biology, Georgetown University Medical Center, Medical-Dental Building, Room C406B, 3900 Reservoir Road, Northwest, Washington, DC 20057 (United States)], E-mail: ppb@georgetown.edu

    2008-12-12

    STAT3 is constitutively activated in several cancers, including prostate cancer, and is therefore, a potential target for cancer therapy. DU-145 prostate cancer cells were stably co-transfected with STAT3 reporter and puromycin resistant plasmids to create a stable STAT3 reporter cell line that can be used for high throughput screening of STAT3 modulators. The applicability of this cell line was tested with two known activators and inhibitors of STAT3. As expected, EGF and IL-6 increased STAT3 reporter activity and enhanced the nuclear localization of phosphorylated STAT3 (pSTAT3); whereas Cucurbitacin I and AG490 decreased STAT3 reporter activity dose and time-dependently and reduced the localization of pSTAT3 in the nuclei of prostate cancer cells. Given the importance of STAT3 in cancer initiation and progression, the development of a stable STAT3 reporter cell line in prostate cancer cells provides a rapid, sensitive, and cost effective method for the screening of potential STAT3 modulators.

  2. Stat3 activation in human endometrial and cervical cancers

    Microsoft Academic Search

    C-L Chen; F-C Hsieh; J C Lieblein; J Brown; C Chan; J A Wallace; G Cheng; B M Hall; J Lin

    2007-01-01

    The activation of signal transducer and activator of transcription 3 (Stat3) has been implicated in the oncogenesis of cancer and is regarded as a novel target for cancer therapy. Stat3 is classified as a proto-oncogene, because an activated form of Stat3 can mediate oncogenic transformation in cultured cells and tumour formation in nude mice. The constitutive activation of Stat3 has

  3. Mitochondrial STAT3 Supports Ras-Dependent Oncogenic Transformation

    Microsoft Academic Search

    Daniel J. Gough; Alicia Corlett; Karni Schlessinger; Joanna Wegrzyn; Andrew C. Larner; David E. Levy

    2009-01-01

    Signal transducer and activator of transcription 3 (STAT3) is a latent cytoplasmic transcription factor responsive to cytokine signaling and tyrosine kinase oncoproteins by nuclear translocation when it is tyrosine-phosphorylated. We report that malignant transformation by activated Ras is impaired without STAT3, in spite of the inability of Ras to drive STAT3 tyrosine phosphorylation or nuclear translocation. Moreover, STAT3 mutants that

  4. Treatment of IL-21R-Fc control autoimmune arthritis via suppression of STAT3 signal pathway mediated regulation of the Th17/Treg balance and plasma B cells.

    PubMed

    Ryu, Jun-Geol; Lee, Jennifer; Kim, Eun-Kyung; Seo, Hyeon-Beom; Park, Jin-Sil; Lee, Seon-Yeong; Moon, Young-Mee; Yoo, Seok-Ho; Park, Young-woo; Park, Sung-Hwan; Cho, Mi-La; Kim, Ho-Youn

    2015-02-01

    Interleukin-21 (IL-21) is a T cell-derived cytokine modulating T cell, B cell, and natural killer cell responses. To determine whether IL-21 contributes to pathologic processes, recombinant IL-21 receptor (R) fusion protein (rhIL-21R-Fc) was examined in mice models of autoimmune arthritis (collagen-induced arthritis). DBA/1J mice were immunized with chicken type II collagen and then treated intraperitoneally with rhIL-21R-Fc, which was initiated after the onset of arthritis symptoms in 20% of the cohort. The mice were assessed 3 times per week for signs of arthritis and histologic features as well as serum immunoglobulin. Cytokine messenger RNA levels in the spleen were also examined. STAT3 phosphorylation is dose dependently activated by IL-21 and inhibited by rhIL-21R-Fc in vitro using T cells. Treatment of DBA/1J mice with rhIL-21R-Fc reduced the clinical and histologic signs of CIA. The IL-17 and STAT3-expressing CD4(+) splenocytes dramatically decreased in the rhIL-21R-Fc treated mice. IL-21R-Fc treated mice also decreased the production of IgG, STAT3 phosphorylation, and plasma cell transcription factor (Blimp1). These findings demonstrate a pathogenic role of IL-21 in animal models of RA, suggesting IL-21 as a promising therapeutic target among human RA. PMID:25447400

  5. Anomalous behaviour of the STAT3 binding site in the human c-myc P2 promoter

    SciTech Connect

    Vougier, Stephanie; Cheung, S.-H.; Li Li; Hodgson, Glenn [Centre for Biochemistry and Cell Biology, School of Biomedical Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH (United Kingdom); Shaw, Peter E [Centre for Biochemistry and Cell Biology, School of Biomedical Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH (United Kingdom)], E-mail: peter.shaw@nottingham.ac.uk

    2007-12-21

    The Signal Transducer and Activator of Transcription 3 (STAT3) is necessary for ES cell renewal, plays critical roles during vertebrate development, and has oncogenic potential. STAT3 also mediates cytokine responses notably in the induction of acute phase response genes in the liver. Thus STAT3 is a pleiotropic regulator during cell proliferation and a cell-specific mediator of pro-inflammatory responses. How STAT3 fulfils both roles is unclear. To address this question we attempted to characterise pre-initiation complexes (PICs) on STAT3-responsive promoters containing the c-myc P2 promoter element (P2E) or c-fos Serum-Inducible Element (SIE). Although both promoters mediated cytokine responses in HepG2 cells, poor binding of STAT1 and STAT3 in vitro precluded isolation of active promoter complexes on the P2E. The inability of STAT3 to bind the P2E in vitro correlated with failure of the P2E to mediate cytokine-responsive gene expression in several other cell types. Thus the c-myc P2E behaves as a dual-purpose STAT3 element with anomalous characteristics in HepG2 cells.

  6. Quercetin abrogates IL-6/STAT3 signaling and inhibits glioblastoma cell line growth and migration

    SciTech Connect

    Michaud-Levesque, Jonathan; Bousquet-Gagnon, Nathalie; Beliveau, Richard, E-mail: oncomol@nobel.si.uqam.ca

    2012-05-01

    Evidence has suggested that STAT3 functions as an oncogene in gliomagenesis. As a consequence, changes in the inflammatory microenvironment are thought to promote tumor development. Regardless of its origin, cancer-related inflammation has many tumor-promoting effects, such as the promotion of cell cycle progression, cell proliferation, cell migration and cell survival. Given that IL-6, a major cancer-related inflammatory cytokine, regulates STAT3 activation and is upregulated in glioblastoma, we sought to investigate the inhibitory effects of the chemopreventive flavonoid quercetin on glioblastoma cell proliferation and migration triggered by IL-6, and to determine the underlying mechanisms of action. In this study, we show that quercetin is a potent inhibitor of the IL-6-induced STAT3 signaling pathway in T98G and U87 glioblastoma cells. Exposure to quercetin resulted in the reduction of GP130, JAK1 and STAT3 activation by IL-6, as well as a marked decrease of the proliferative and migratory properties of glioblastoma cells induced by IL-6. Interestingly, quercetin also modulated the expression of two target genes regulated by STAT3, i.e. cyclin D1 and matrix metalloproteinase-2 (MMP-2). Moreover, quercetin reduced the recruitment of STAT3 at the cyclin D1 promoter and inhibited Rb phosphorylation in the presence of IL-6. Overall, these results provide new insight into the role of quercetin as a blocker of the STAT3 activation pathway stimulated by IL-6, with a potential role in the prevention and treatment of glioblastoma.

  7. Epstein-Barr virus-associated primary central nervous system lymphomas in immunocompetent elderly patients: analysis for latent membrane protein-1 oncogene deletion and EBNA-2 strain typing.

    PubMed

    Sugita, Yasuo; Terasaki, Mizuhiko; Niino, Daisuke; Ohshima, Koichi; Fumiko, Arakawa; Shigemori, Minoru; Sato, Yasuharu; Asano, Naoko

    2010-11-01

    Epstein-Barr virus (EBV) has been implicated in the pathogenesis of primary central nervous system lymphomas (PCNLs) in immunocompetent hosts. To investigate the role of EBV in the pathogenesis of PCNLs in immunocompetent hosts, this study assessed six PCNL cases (elderly male immunocompetent patients; age ?60 years) histologically and immunohistochemically, and an EBV genetic study was performed. Histologically, all cases were diagnosed as diffuse large B-cell lymphoma with extensive necrosis. In all six cases, PCNL cells showed immunohistochemical positivity for latent membrane protein 1 (LMP-1) and Epstein-Barr nuclear 2 (EBNA2). Lymphoma cells also showed positive signals for EBV-encoded small RNAs (EBERs) on in-situ hybridization. EBV subtyping-PCR analysis demonstrated that one case was EBNA 2B type and the other five cases were EBNA 2A type, and two cases were EBV wild-type and four cases showed 30-bp LMP-1 deletion by PCR analysis. It is therefore possible that LMP gene deletion or EBNA-2 strain type are important in the tumorigenesis of EBV-positive PCNLs. In addition, EBV-positive PCNLs in immunocompetent hosts may be related to immunological deterioration derived from the aging process. PMID:20455004

  8. 12-O-Tetradecanoylphorbol-13-acetate Inhibits Melanoma Growth by Inactivation of STAT3 through Protein Kinase C-activated Tyrosine Phosphatase(s)*

    PubMed Central

    Oka, Masahiro; Sumita, Naoko; Sakaguchi, Masanobu; Iwasaki, Tetsushi; Bito, Toshinori; Kageshita, Toshiro; Sato, Ken-ichi; Fukami, Yasuo; Nishigori, Chikako

    2009-01-01

    The growth of most melanoma cells in vitro is inhibited by the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). In this study, the involvement of the signal transducer and activator of transcription 3 (STAT3) in the TPA-induced growth inhibition of melanoma cells was examined. The in vitro growth and DNA synthesis of five melanoma cell lines, whose STAT3 was activated (phosphorylated), was inhibited by TPA, whereas that of WM35 and WM39 cells, whose STAT3 activity was at negligible levels, was considerably slow and not affected by TPA. Blockade of STAT3 activity by small interfering RNAs suppressed the growth of WM1205Lu cells containing constitutively activated STAT3. Treatment of WM1205Lu cells with TPA decreased both the phosphorylated STAT3 and the DNA-binding activity of STAT3. Pretreatment of WM1205Lu cells with either a protein-tyrosine phosphatase inhibitor or a protein kinase C (PKC) inhibitor prevented the inhibitory effects of TPA on the level of phosphorylated STAT3. The five melanoma cell lines containing phosphorylated STAT3 commonly expressed PKC?, PKC?, and PKC?. Introduction of the dominant negative mutant of one of these PKC isoforms into WM1205Lu cells inhibited the TPA-induced dephosphorylation of STAT3. A Src inhibitor attenuated the STAT3 phosphorylation in WM1205Lu cells. These results indicate that constitutively activated STAT3 is positively regulated by c-Src and negatively regulated by a PKC-activated tyrosine phosphatase(s) in melanoma cells. Because TPA did not affect c-Src activity, we conclude that the growth inhibitory effect of TPA on melanoma cells is mediated through inactivation of STAT3 by a PKC-activated tyrosine phosphatase(s). PMID:19755418

  9. Influence of the Epstein-Barr virus nuclear antigen EBNA 2 on the growth phenotype of virus-transformed B cells.

    PubMed Central

    Rickinson, A B; Young, L S; Rowe, M

    1987-01-01

    Epstein-Barr virus (EBV) isolates show sequence divergence in the BamHI YH region of the genome which encodes the nuclear antigen EBNA 2, a protein thought to be involved in the initiation of virus-induced B-cell transformation; type A isolates (such as B95-8 EBV) encode a 82- to 87-kilodalton EBNA 2A protein, whereas type B isolates (such as AG876 EBV) encode an antigenically distinct 75-kilodalton EBNA 2B protein. In the present work 12 type A isolates and 8 type B isolates have been compared for their ability to transform resting human B cells in vitro into permanent lymphoblastoid cell lines. Although the kinetics of initial focus formation was not markedly dependent upon the EBNA 2 type of the transforming virus, on subsequent passage type A virus-transformed cells (type A transformants) yielded cell lines much more readily than did type B transformants. Direct comparison between the two types of transformant revealed clear differences in several aspects of growth phenotype. Compared with type A transformants, cell lines established with type B virus isolates consistently displayed an unusual growth pattern with poor survival of individual cells shed from lymphoblastoid clumps, a lower growth rate and a greater sensitivity to seeding at limiting dilutions, and a significantly lower saturation density that could not be corrected by supplementation of the medium with culture supernatant containing B-cell growth factors. This is the first direct evidence that, in EBV-transformed B-cell lines, the EBNA 2 protein plays a continuing role in determining the cellular growth phenotype. Images PMID:3033261

  10. STAT3-Mediated Metabolic Reprograming in Cellular Transformation and Implications for Drug Resistance.

    PubMed

    Poli, Valeria; Camporeale, Annalisa

    2015-01-01

    Signal transducer and activator of transcription (STAT)3 mediates the signaling downstream of cytokine and growth factor receptors, regulating the expression of target genes. It is constitutively phosphorylated on tyrosine (Y-P) in many tumors, where its transcriptional activity can induce a metabolic switch toward aerobic glycolysis and down-regulate mitochondrial activity, a prominent metabolic feature of most cancer cells, correlating with reduced production of ROS, delayed senescence, and protection from apoptosis. STAT3 can, however, also localize to mitochondria, where its serine-phosphorylated (S-P) form preserves mitochondrial oxidative phosphorylation and controls the opening of the mitochondrial permeability transition pore, also promoting survival and resistance to apoptosis in response to specific signals/oncogenes such as RAS. Thus, downstream of different signals, both nuclear, Y-P STAT3, and mitochondrial, S-P STAT3, can act by promoting cell survival and reducing ROS production. Here, we discuss these properties in the light of potential connections between STAT3-driven alterations of mitochondrial metabolism and the development of drug resistance in cancer patients. PMID:26106584

  11. STAT3-Mediated Metabolic Reprograming in Cellular Transformation and Implications for Drug Resistance

    PubMed Central

    Poli, Valeria; Camporeale, Annalisa

    2015-01-01

    Signal transducer and activator of transcription (STAT)3 mediates the signaling downstream of cytokine and growth factor receptors, regulating the expression of target genes. It is constitutively phosphorylated on tyrosine (Y-P) in many tumors, where its transcriptional activity can induce a metabolic switch toward aerobic glycolysis and down-regulate mitochondrial activity, a prominent metabolic feature of most cancer cells, correlating with reduced production of ROS, delayed senescence, and protection from apoptosis. STAT3 can, however, also localize to mitochondria, where its serine-phosphorylated (S-P) form preserves mitochondrial oxidative phosphorylation and controls the opening of the mitochondrial permeability transition pore, also promoting survival and resistance to apoptosis in response to specific signals/oncogenes such as RAS. Thus, downstream of different signals, both nuclear, Y-P STAT3, and mitochondrial, S-P STAT3, can act by promoting cell survival and reducing ROS production. Here, we discuss these properties in the light of potential connections between STAT3-driven alterations of mitochondrial metabolism and the development of drug resistance in cancer patients.

  12. Peroxiredoxin-2 and STAT3 form a redox relay for H2O2 signaling.

    PubMed

    Sobotta, Mirko C; Liou, Willy; Stöcker, Sarah; Talwar, Deepti; Oehler, Michael; Ruppert, Thomas; Scharf, Annette N D; Dick, Tobias P

    2015-01-01

    Hydrogen peroxide (H(2)O(2)) acts as a signaling messenger by oxidatively modifying distinct cysteinyl thiols in distinct target proteins. However, it remains unclear how redox-regulated proteins, which often have low intrinsic reactivity towards H(2)O(2) (k(app) ?1-10 M(-1) s(-1)), can be specifically and efficiently oxidized by H(2)O(2). Moreover, cellular thiol peroxidases, which are highly abundant and efficient H(2)O(2) scavengers, should effectively eliminate virtually all of the H(2)O(2) produced in the cell. Here, we show that the thiol peroxidase peroxiredoxin-2 (Prx2), one of the most H(2)O(2)-reactive proteins in the cell (k(app) ?10(7)-10(8) M(-1) s(-1)), acts as a H(2)O(2) signal receptor and transmitter in transcription factor redox regulation. Prx2 forms a redox relay with the transcription factor STAT3 in which oxidative equivalents flow from Prx2 to STAT3. The redox relay generates disulfide-linked STAT3 oligomers with attenuated transcriptional activity. Cytokine-induced STAT3 signaling is accompanied by Prx2 and STAT3 oxidation and is modulated by Prx2 expression levels. PMID:25402766

  13. Two Naturally Occurring Terpenes, Dehydrocostuslactone and Costunolide, Decrease Intracellular GSH Content and Inhibit STAT3 Activation

    PubMed Central

    Butturini, Elena; Cavalieri, Elisabetta; Carcereri de Prati, Alessandra; Darra, Elena; Rigo, Antonella; Shoji, Kazuo; Murayama, Norie; Yamazaki, Hiroshi; Watanabe, Yasuo; Suzuki, Hisanori; Mariotto, Sofia

    2011-01-01

    The main purpose of the present study is to envisage the molecular mechanism of inhibitory action ofdehydrocostuslactone (DCE) andcostunolide (CS), two naturally occurring sesquiterpene lactones, towards the activation of signal transducer and activator of transcription 3 (STAT3). We report that, in human THP-1 cell line, they inhibit IL-6-elicited tyrosine phosphorylation of STAT3 and its DNA binding activity with EC50 of 10 µM with concomitantdown-regulation ofthe phosphorylation of the tyrosine Janus kinases JAK1, JAK2 and Tyk2. Furthermore, these compounds that contain an ?-?-unsatured carbonyl moiety and function as potent Michael reaction acceptor, induce a rapid drop in intracellular glutathione (GSH) concentration by direct interaction with it, thereby triggering S-glutathionylation of STAT3. Dehydrocostunolide (HCS), the reduced form of CS lacking only the ?-?-unsaturated carbonyl group, fails to exert any inhibitory action. Finally, the glutathione ethylene ester (GEE), the cell permeable GSH form, reverts the inhibitory action of DCE and CS on STAT3 tyrosine phosphorylation. We conclude that these two sesquiterpene lactones are able to induce redox-dependent post-translational modification of cysteine residues of STAT3 protein in order to regulate its function. PMID:21625597

  14. SIRT1 counteracted the activation of STAT3 and NF-?B to repress the gastric cancer growth.

    PubMed

    Lu, Juanjuan; Zhang, Liping; Chen, Xiang; Lu, Qiming; Yang, Yuxia; Liu, Jingping; Ma, Xin

    2014-01-01

    Sirtuin-1 (SIRT1) possesses apparently dual roles in regulation of tumor. Previous reports have documented the crosstalk between SIRT1 with signal transducer and activator of transcription 3 (STAT3) and nuclear factor kappa-B (NF-?B) signaling in leukemia, lymphoma and myeloma. In this study, the purpose was to survey the regulatory effects of SIRT1 on gastric cancer (GC) cells (AGS and MKN-45) and the relationships between SIRT1 and activation of STAT3 and NF-?B in GC cells. We found the SIRT1 activator (resveratrol RSV) contributed to the repression of viability and increase of senescence, which were rescued by SIRT1 inhibitor (nicotinamide NA) and SIRT1 depletion by CCK-8 assay and SA-?-gal assay respectively. Further study found SIRT1 activation (RSV supplement) not only inhibited the activation of STAT3 including STAT3 mRNA level, c-myc mRNA level phosphorylated STAT3 (pSTAT3) proteins and acetylizad STAT3 (acSTAT3) proteins, but also repression of pNF-?B p65 and acNF-?B p65. NA reversed the effects of RSV. In addition, either RSV or NA application could not change the cellular viability and senescence in MKN-45 cells with STAT3 knockdown or NF-?B knockdown. Overall, our findings suggested SIRT1 activation could induced the loss of viability and increases of senescence in GC in vitro. Moreover, our observations revealed SIRT1 displayed growth inhibitory activity in GC cells highly associated with causing repression of activation of STAT3 and NF-?B proteins via deacetylation. PMID:25664004

  15. SIRT1 counteracted the activation of STAT3 and NF-?B to repress the gastric cancer growth

    PubMed Central

    Lu, Juanjuan; Zhang, Liping; Chen, Xiang; Lu, Qiming; Yang, Yuxia; Liu, Jingping; Ma, Xin

    2014-01-01

    Sirtuin-1 (SIRT1) possesses apparently dual roles in regulation of tumor. Previous reports have documented the crosstalk between SIRT1 with signal transducer and activator of transcription 3 (STAT3) and nuclear factor kappa-B (NF-?B) signaling in leukemia, lymphoma and myeloma. In this study, the purpose was to survey the regulatory effects of SIRT1 on gastric cancer (GC) cells (AGS and MKN-45) and the relationships between SIRT1 and activation of STAT3 and NF-?B in GC cells. We found the SIRT1 activator (resveratrol RSV) contributed to the repression of viability and increase of senescence, which were rescued by SIRT1 inhibitor (nicotinamide NA) and SIRT1 depletion by CCK-8 assay and SA-?-gal assay respectively. Further study found SIRT1 activation (RSV supplement) not only inhibited the activation of STAT3 including STAT3 mRNA level, c-myc mRNA level phosphorylated STAT3 (pSTAT3) proteins and acetylizad STAT3 (acSTAT3) proteins, but also repression of pNF-?B p65 and acNF-?B p65. NA reversed the effects of RSV. In addition, either RSV or NA application could not change the cellular viability and senescence in MKN-45 cells with STAT3 knockdown or NF-?B knockdown. Overall, our findings suggested SIRT1 activation could induced the loss of viability and increases of senescence in GC in vitro. Moreover, our observations revealed SIRT1 displayed growth inhibitory activity in GC cells highly associated with causing repression of activation of STAT3 and NF-?B proteins via deacetylation. PMID:25664004

  16. Inhibition of the JAK2/STAT3 Pathway Reduces Gastric Cancer Growth In Vitro and In Vivo

    PubMed Central

    Ling, Hui; Jackson, Cameron B.; Howlett, Meegan; Kalantzis, Anastasia; Priebe, Waldemar; Giraud, Andrew S.

    2014-01-01

    Signal Transducer and Activator of Transcription-3 (STAT3) is constitutively activated in many cancers where it promotes growth, inflammation, angiogenesis and inhibits apoptosis. We have shown that STAT3 is constitutively activated in human gastric cancer, and that chronic IL-11-driven STAT3 transcriptional activity induces gastric tumourigenesis in the gp130757FF mouse model of gastric cancer development. Here we show that treatment of human AGS gastric cancer cells with the Janus Kinase (JAK) inhibitor WP1066 dose-, and time-dependently inhibits STAT3 phosphorylation, in conjunction with reduced JAK2 phosphorylation, reduced proliferation and increased apoptosis. In addition, application of intraperitoneal WP1066 for 2 weeks, reduced gastric tumour volume by 50% in the gp130757FF mouse coincident with reduced JAK2 and STAT3 activation compared with vehicle-treated, littermate controls. Gastric tumours from WP1066- treated mice had reduced polymorphonuclear inflammation, coincident with inhibition of numerous proinflammatory cytokines including IL-11, IL-6 and IL-1?, as well as the growth factors Reg1 and amphiregulin. These results show that WP1066 can block proliferation, reduce inflammation and induce apoptosis in gastric tumour cells by inhibiting STAT3 phosphorylation, and that many cytokines and growth factors that promote gastric tumour growth are regulated by STAT3-dependent mechanisms. WP1066 may form the basis for future therapeutics against gastric cancer. PMID:24804649

  17. RANKL downregulates cell surface CXCR6 expression through JAK2/STAT3 signaling pathway during osteoclastogenesis

    SciTech Connect

    Li, Changhong; Zhao, Jinxia; Sun, Lin; Yao, Zhongqiang; Liu, Rui [Department of Rheumatology and Immunology, Peking University Third Hospital, Beijing 100191 (China)] [Department of Rheumatology and Immunology, Peking University Third Hospital, Beijing 100191 (China); Huang, Jiansheng [Department of Pediatrics, Washington University School of Medicine, St. Louis, MO (United States)] [Department of Pediatrics, Washington University School of Medicine, St. Louis, MO (United States); Liu, Xiangyuan, E-mail: liu-xiangyuan@263.net [Department of Rheumatology and Immunology, Peking University Third Hospital, Beijing 100191 (China)] [Department of Rheumatology and Immunology, Peking University Third Hospital, Beijing 100191 (China)

    2012-12-14

    Highlights: Black-Right-Pointing-Pointer CXCR6 is down-regulated during RANKL-induced osteoclastogenesis in RAW264.7 cells. Black-Right-Pointing-Pointer CXCR6 reduction was nearly reversed by inhibition of JAK2/STAT3 signaling pathway. Black-Right-Pointing-Pointer CXCL16 alone does not positively regulate osteoclastogenesis. -- Abstract: The receptor activator of nuclear factor-{kappa}B ligand (RANKL), as a member of the tumor necrosis factor (TNF) family, plays an essential role in osteoclast differentiation and function. Chemokines and their receptors have recently been shown to play critical roles in osteoclastogenesis, however, whether CXCL16-CXCR6 plays role in RANKL-mediated osteoclastogenesis is unknown. In this study, we first reported that RANKL decreased CXCR6 in a dose-dependent manner, which may be through deactivation of Akt and STAT3 signaling induced by CXCL16. Interestingly, RANKL-mediated CXCR6 reduction may be associated to the activation of STAT3 by phosphorylation. When STAT3 activation was blocked by JAK2/STAT3 inhibitor AG490, RANKL failed to shut down CXCR6 expression during osteoclastogenesis. However, CXCL16 alone did not augment RANKL-mediated osteoclast differentiation and did not alter RANKL-receptor RANK mRNA expression. These results demonstrate that reduction of CXCL16-CXCR6 is critical in RANKL-mediated osteoclastogenesis, which is mainly through the activation of JAK2/STAT3 signaling. CXCL16-CXCR6 axis may become a novel target for the therapeutic intervention of bone resorbing diseases such as rheumatoid arthritis and osteoporosis.

  18. STAT3 in Cancer—Friend or Foe?

    PubMed Central

    Zhang, Hai-Feng; Lai, Raymond

    2014-01-01

    The roles and significance of STAT3 in cancer biology have been extensively studied for more than a decade. Mounting evidence has shown that constitutive activation of STAT3 is a frequent biochemical aberrancy in cancer cells, and this abnormality directly contributes to tumorigenesis and shapes many malignant phenotypes in cancer cells. Nevertheless, results from more recent experimental and clinicopathologic studies have suggested that STAT3 also can exert tumor suppressor effects under specific conditions. Importantly, some of these studies have demonstrated that STAT3 can function either as an oncoprotein or a tumor suppressor in the same cell type, depending on the specific genetic background or presence/absence of specific coexisting biochemical defects. Thus, in the context of cancer biology, STAT3 can be a friend or foe. In the first half of this review, we will highlight the “evil” features of STAT3 by summarizing its oncogenic functions and mechanisms. The differences between the canonical and non-canonical pathway will be highlighted. In the second half, we will summarize the evidence supporting that STAT3 can function as a tumor suppressor. To explain how STAT3 may mediate its tumor suppressor effects, we will discuss several possible mechanisms, one of which is linked to the role of STAT3?, one of the two STAT3 splicing isoforms. Taken together, it is clear that the roles of STAT3 in cancer are multi-faceted and far more complicated than one appreciated previously. The new knowledge has provided us with new approaches and strategies when we evaluate STAT3 as a prognostic biomarker or therapeutic target. PMID:24995504

  19. Critical role for Stat3 in T-dependent terminal differentiation of IgG B cells

    PubMed Central

    Fornek, Jamie L.; Tygrett, Lorraine T.; Waldschmidt, Thomas J.; Poli, Valeria; Rickert, Robert C.; Kansas, Geoffrey S.

    2006-01-01

    Stat proteins are latent cytoplasmic transcription factors that are crucial in many aspects of mammalian development. In the immune system, Stat3 has distinct roles in T-cell, neutrophil, and macrophage function, but a role for Stat3 in B-cell development, particularly in the terminal differentiation of B cells into antibody-secreting plasma cells, has never been directly tested. In this study, we used the Cre/lox system to generate a mouse strain in which Stat3 was conditionally deleted in the B-cell lineage (Stat3fl/flCD19Cre/+). B-cell development, establishment of the peripheral B-cell compartment, and baseline serum antibody levels were unperturbed in Stat3fl/flCD19Cre/+ mice. Strikingly, Stat3fl/flCD19Cre/+ mice displayed profound defects in T-dependent (TD) IgG responses, but normal TD IgM, IgE, and IgA responses and T-independent (TI) IgM and IgG3 responses. In addition, germinal center (GC) formation, isotype switching, and generation of memory B cells, including IgG+ memory cells, were all intact in Stat3fl/flCD19Cre/+ mice, indicating that the requirement for Stat3 was limited to plasma cell differentiation. These results demonstrate a profound yet highly selective role for Stat3 in TD IgG plasma cell differentiation, and therefore represent a unique example of a transcription factor regulating isotype-specific terminal B-cell differentiation. PMID:16223771

  20. A subpopulation of normal B cells latently infected with Epstein-Barr virus resembles Burkitt lymphoma cells in expressing EBNA-1 but not EBNA-2 or LMP1.

    PubMed Central

    Chen, F; Zou, J Z; di Renzo, L; Winberg, G; Hu, L F; Klein, E; Klein, G; Ernberg, I

    1995-01-01

    Using reverse transcription of whole cellular RNA and nested PCR, we have performed experiments mixing different proportions of Epstein-Barr virus (EBV)-carrying and EBV-negative cells. Based on the results, a method that detects viral transcripts for EBNA-1, EBNA-2, LMP1, and LMP2a from less than one positive cell among 10(5) negative cells was developed. With this method we have shown that the EBV DNA positive cells among small, high-density peripheral blood B-lymphocytes of normal healthy persons express EBNA-1-mRNA but not EBNA-2 or LMP1. A similar EBV expression pattern is found in type I Burkitt lymphoma cells. We suggest that the expression pattern in the lymphoma cells reflects the viral strategy in normal resting B cells and meets the requirements of latent persistence. PMID:7745723

  1. Hypothyroidism reduces ObRb-STAT3 leptin signalling in the hypothalamus and pituitary of rats associated with resistance to leptin acute anorectic action.

    PubMed

    Calvino, Camila; Souza, Luana L; Costa-e-Sousa, Ricardo H; Almeida, Norma A S; Trevenzoli, Isis H; Pazos-Moura, Carmen C

    2012-10-01

    Leptin has been shown to regulate the hypothalamus-pituitary-thyroid axis, acting primarily through the STAT3 pathway triggered through the binding of leptin to the long-chain isoform of the leptin receptor, ObRb. We previously demonstrated that although hyperthyroid rats presented leptin effects on TSH secretion, those effects were abolished in hypothyroid rats. We addressed the hypothesis that changes in the STAT3 pathway might explain the lack of TSH response to leptin in hypothyroidism by evaluating the protein content of components of leptin signalling via the STAT3 pathway in the hypothalamus and pituitary of hypothyroid (0·03% methimazole in the drinking water/21 days) and hyperthyroid (thyroxine 5 ?g/100 g body weight /5 days) rats. Hypothyroid rats exhibited decreased ObRb and phosphorylated STAT3 (pSTAT3) protein in the hypothalamus, and in the pituitary gland they exhibited decreased ObRb, total STAT3, pSTAT3 and SOCS3 (P<0·05). Except for a modest decrease in pituitary STAT3, no other alterations were observed in hyperthyroid rats. Moreover, unlike euthyroid rats, the hypothyroid rats did not exhibit a reduction in food ingestion after a single injection of leptin (0·5 mg/kg body weight). Therefore, hypothyroidism decreased ObRb-STAT3 signalling in the hypothalamus and pituitary gland, which likely contributes to the loss of leptin action on food intake and TSH secretion, as previously observed in hypothyroid rats. PMID:22875962

  2. Association of Toxicity of Sorafenib and Sunitinib for Human Keratinocytes with Inhibition of Signal Transduction and Activator of Transcription 3 (STAT3)

    PubMed Central

    Yamamoto, Kazuhiro; Mizumoto, Atsushi; Nishimura, Kohji; Uda, Atsushi; Mukai, Akira; Yamashita, Kazuhiko; Kume, Manabu; Makimoto, Hiroo; Bito, Toshinori; Nishigori, Chikako; Nakagawa, Tsutomu; Hirano, Takeshi; Hirai, Midori

    2014-01-01

    Hand–foot skin reaction is a most common multi-kinase inhibitor-related adverse event. This study aimed to examine whether the toxicity of sorafenib and sunitinib for human keratinocytes was associated with inhibiting signal transduction and activator of transcription 3 (STAT3). We studied whether STAT3 activity affects sorafenib- and sunitinib-induced cell growth inhibition in HaCaT cells by WST-8 assay. Stattic enhanced the cell-growth inhibitory and apoptotic effects of sorafenib and sunitinib. HaCaT cells transfected with constitutively-active STAT3 (STAT3C) were resistant to the sorafenib- and sunitinib-induced cell growth inhibition. STAT3 activity decreased after short-term treatment with sorafenib and sunitinib in a dose-dependent manner and recovered after long-term treatment with sorafenib and sunitinib at low doses. Moreover, the expression of survivin and bcl-2 decreased after treatment with sorafenib and sunitinib was concomitant with variations in STAT3 activity. Sorafenib-induced STAT3 inhibition was mediated by regulation via MAPK pathways in HaCaT cells, while sunitinib-induced STAT3 inhibition was not. Thus, STAT3 activation mediating apoptosis suppressors may be a key factor in sorafenib and sunitinib-induced keratinocyte cytotoxicity. PMID:25013907

  3. STAT3-dependent transactivation of miRNA genes following Toxoplasma gondii infection in macrophage

    PubMed Central

    2013-01-01

    Background The apicomplexan parasite Toxoplasma gondii can infect and replicate in virtually any nucleated cell in many species of warm-blooded animals; T. gondii has elaborate mechanisms to counteract host-cell apoptosis in order to maintain survival and breed in the host cells. Methods Using microarray profiling and a combination of conventional molecular approaches, we investigated the levels of microRNAs (miRNAs ) in human macrophage during T. gondii infection. We used molecular tools to examine Toxoplasma-upregualted miRNAs to revealed potential signal transducers and activators of transcription 3(STAT3) binding sites in the promoter elements of a subset of miRNA genes. We analysed the apoptosis of human macrophage with the functional inhibition of the STAT3-binding miRNAs by flow cytometry. Results Our results demonstrated differential alterations in the mature miRNA expression profile in human macrophage following T. gondii infection. Database analysis of Toxoplasma-upregulated miRNAs revealed potential STAT3 binding sites in the promoter elements of a subset of miRNA genes. We demonstrated that miR-30c-1, miR-125b-2, miR-23b-27b-24-1 and miR-17?~?92 cluster genes were transactivated through promoter binding of the STAT3 following T. gondii infection. Importantly, functional inhibition of selected STAT3-binding miRNAs in human macropahges increased apoptosis of host cells. Conclusions A panel of miRNAs is regulated through promoter binding of the STAT3 in human macrophage and these miRNAs are involved in anti-apoptosis in response to T. gondii infection. PMID:24341525

  4. Depletion of cellular glutathione modulates LIF-induced JAK1-STAT3 signaling in cardiac myocytes.

    PubMed

    Kurdi, Mazen; Sivakumaran, Vidhya; Duhé, Roy J; Aon, Miguel A; Paolocci, Nazareno; Booz, George W

    2012-12-01

    Previously we reported that the sesquiterpene lactone parthenolide induces oxidative stress in cardiac myocytes, which blocks Janus kinase (JAK) activation by the interleukin 6 (IL-6)-type cytokines. One implication suggested by this finding is that IL-6 signaling is dependent upon cellular anti-oxidant defenses or redox status. Therefore, the present study was undertaken to directly test the hypothesis that JAK1 signaling by the IL-6-type cytokines in cardiac myocytes is impaired by glutathione (GSH) depletion, since this tripeptide is one of the major anti-oxidant molecules and redox-buffers in cells. Cardiac myocytes were pretreated for 6h with l-buthionine-sulfoximine (BSO) to inhibit GSH synthesis. After 24h, cells were dosed with the IL-6-like cytokine, leukemia inhibitory factor (LIF). BSO treatment decreased GSH levels and dose-dependently attenuated activation of JAK1, Signal Transducer and Activator of Transcription 3 (STAT3), and extracellular signal regulated kinases 1 and 2 (ERK1/2). Addition of glutathione monoethyl ester, which is cleaved intracellularly to GSH, prevented attenuation of LIF-induced JAK1 and STAT3 activation, as did the reductant N-acetyl-cysteine. Unexpectedly, LIF-induced STAT1 activation was unaffected by GSH depletion. Evidence was found that STAT3 is more resistant than STAT1 to intermolecular disulfide bond formation under oxidizing conditions and more likely to retain the monomeric form, suggesting that conformational differences explain the differential effect of GSH depletion on STAT1 and STAT3. Overall, our findings indicate that activation of both JAK1 and STAT3 is redox-sensitive and the character of IL-6 type cytokine signaling in cardiac myocytes is sensitive to changes in the cellular redox status. In cardiac myocytes, activation of STAT1 may be favored over STAT3 under oxidizing conditions due to GSH depletion and/or augmented reactive oxygen species production, such as in ischemia-reperfusion and heart failure. PMID:22939972

  5. RECK Controls Breast Cancer Metastasis by Modulating a Convergent, STAT3-dependent Neoangiogenic Switch

    PubMed Central

    Walsh, Logan A.; Roy, David M.; Reyngold, Marsha; Giri, Dilip; Snyder, Alexandra; Turcan, Sevin; Badwe, Chaitanya R.; Lyman, Jaclyn; Bromberg, Jacqueline; King, Tari A.; Chan, Timothy A.

    2014-01-01

    Metastasis is the primary cause of cancer-related death in oncology patients. A comprehensive understanding of the molecular mechanisms that cancer cells usurp to promote metastatic dissemination is critical for the development and implementation of novel diagnostic and treatment strategies. Here we show that the membrane protein RECK, controls breast cancer metastasis by modulating a novel, non-canonical and convergent STAT3-dependent angiogenic program. Neoangiogenesis and STAT3 hyperactivation are known to be fundamentally important for metastasis but the root molecular initiators of these phenotypes are poorly understood. Our study identifies loss of RECK as a critical and previously unknown trigger for these hallmarks of metastasis. Using multiple xenograft mouse models, we comprehensively show that RECK inhibits metastasis, concomitant with a suppression of neoangiogenesis at secondary sites, while leaving primary tumour growth unaffected. Further, with functional genomics and biochemical dissection we demonstrate that RECK controls this angiogenic rheostat through a novel complex with cell surface receptors to regulate STAT3 activation, cytokine signaling, and the induction of both VEGF and uPA. In accordance with these findings, inhibition of STAT3 can rescue this phenotype both in vitro and in vivo. Taken together, our study uncovers, for the first time, that RECK is a novel regulator of multiple well-established and robust mediators of metastasis; thus, RECK is a keystone protein that may be exploited in a clinical setting to target metastatic disease from multiple angles. PMID:24931164

  6. Leptin-STAT3-G9a Signaling Promotes Obesity-Mediated Breast Cancer Progression.

    PubMed

    Chang, Chao-Ching; Wu, Meng-Ju; Yang, Jer-Yen; Camarillo, Ignacio G; Chang, Chun-Ju

    2015-06-01

    Obesity has been linked to breast cancer progression but the underlying mechanisms remain obscure. Here we report how leptin, an obesity-associated adipokine, regulates a transcriptional pathway to silence a genetic program of epithelial homeostasis in breast cancer stem-like cells (CSC) that promotes malignant progression. Using genome-wide ChIP-seq and RNA expression profiling, we defined a role for activated STAT3 and G9a histone methyltransferase in epigenetic silencing of miR-200c, which promotes the formation of breast CSCs defined by elevated cell surface levels of the leptin receptor (OBR(hi)). Inhibiting the STAT3/G9a pathway restored expression of miR-200c, which in turn reversed the CSC phenotype to a more differentiated epithelial phenotype. In a rat model of breast cancer driven by diet-induced obesity, STAT3 blockade suppressed the CSC-like OBR(hi) population and abrogated tumor progression. Together, our results show how targeting STAT3-G9a signaling regulates CSC plasticity during obesity-related breast cancer progression, suggesting a novel therapeutic paradigm to suppress CSC pools and limit breast malignancy. Cancer Res; 75(11); 2375-86. ©2015 AACR. PMID:25840984

  7. Physical and functional interactions between STAT3 and ZIP kinase

    Microsoft Academic Search

    Noriko Sato; Taro Kawai; Kenji Sugiyama; Ryuta Muromoto; Seiyu Imoto; Yuichi Sekine; Masato Ishida; Shizuo Akira; Tadashi Matsuda

    2005-01-01

    Signal transducer and activator of transcription 3 (STAT3) is a latent cytoplasmic transcription factor that can be activated by cytokines and growth factors. It plays important roles in cell growth, apoptosis and cell transformation, and is constitutively active in a variety of tumor cells. In this study, we provide evidence that zipper-interacting protein kinase (ZIPK) interacts physically with STAT3. ZIPK

  8. Stat3 Controls Cell Movements during Zebrafish Gastrulation

    Microsoft Academic Search

    Susumu Yamashita; Chiemi Miyagi; Amanda Carmany-Rampey; Takashi Shimizu; Ritsuko Fujii; Alexander F. Schier; Toshio Hirano

    2002-01-01

    Vertebrate axis formation requires both the correct specification of cell fates and the coordination of gastrulation movements. We report that the zebrafish signal transducer and activator of transcription 3 (Stat3) is activated on the dorsal side by the maternal Wnt\\/?-catenin pathway. Zebrafish embryos lacking Stat3 activity display abnormal cell movements during gastrulation, resulting in a mispositioned head and a shortened

  9. Hes1 promotes the IL-22-mediated antimicrobial response by enhancing STAT3-dependent transcription in human intestinal epithelial cells

    SciTech Connect

    Murano, Tatsuro [Department of Gastroenterology and Hepatology, Graduate School, Tokyo Medical and Dental University, Tokyo (Japan)] [Department of Gastroenterology and Hepatology, Graduate School, Tokyo Medical and Dental University, Tokyo (Japan); Okamoto, Ryuichi, E-mail: rokamoto.gast@tmd.ac.jp [Department of Gastroenterology and Hepatology, Graduate School, Tokyo Medical and Dental University, Tokyo (Japan) [Department of Gastroenterology and Hepatology, Graduate School, Tokyo Medical and Dental University, Tokyo (Japan); Department of Advanced GI Therapeutics, Graduate School, Tokyo Medical and Dental University, Tokyo (Japan); Ito, Go; Nakata, Toru; Hibiya, Shuji; Shimizu, Hiromichi; Fujii, Satoru; Kano, Yoshihito; Mizutani, Tomohiro; Yui, Shiro; Akiyama-Morio, Junko; Nemoto, Yasuhiro [Department of Gastroenterology and Hepatology, Graduate School, Tokyo Medical and Dental University, Tokyo (Japan)] [Department of Gastroenterology and Hepatology, Graduate School, Tokyo Medical and Dental University, Tokyo (Japan); Tsuchiya, Kiichiro; Nakamura, Tetsuya [Department of Gastroenterology and Hepatology, Graduate School, Tokyo Medical and Dental University, Tokyo (Japan) [Department of Gastroenterology and Hepatology, Graduate School, Tokyo Medical and Dental University, Tokyo (Japan); Department of Advanced GI Therapeutics, Graduate School, Tokyo Medical and Dental University, Tokyo (Japan); Watanabe, Mamoru [Department of Gastroenterology and Hepatology, Graduate School, Tokyo Medical and Dental University, Tokyo (Japan)] [Department of Gastroenterology and Hepatology, Graduate School, Tokyo Medical and Dental University, Tokyo (Japan)

    2014-01-17

    Highlights: •Hes1 enhances IL-22-STAT3 signaling in human intestinal epithelial cells. •Hes1 enhances REG family gene induction by IL-22-STAT3 signaling. •Protein level of Hes1 restricts the response to IL-22. •Present regulation of a cytokine signal represents a new mode of Hes1 function. -- Abstract: Notch signaling plays an essential role in the proliferation and differentiation of intestinal epithelial cells (IECs). We have previously shown that Notch signaling is up-regulated in the inflamed mucosa of ulcerative colitis (UC) and thereby plays an indispensable role in tissue regeneration. Here we show that in addition to Notch signaling, STAT3 signaling is highly activated in the inflamed mucosa of UC. Forced expression of the Notch target gene Hes1 dramatically enhanced the IL-22-mediated STAT3-dependent transcription in human IECs. This enhancement of STAT3-dependent transcription was achieved by the extended phosphorylation of STAT3 by Hes1. Microarray analysis revealed that Hes1-mediated enhancement of IL-22-STAT3 signaling significantly increased the induction of genes encoding antimicrobial peptides, such as REG1A, REG3A and REG3G, in human IECs. Conversely, the reduction of Hes1 protein levels with a ?-secretase inhibitor significantly down-regulated the induction of those genes in IECs, resulting in a markedly poor response to IL-22. Our present findings identify a new role for the molecular function of Hes1 in which the protein can interact with cytokine signals and regulate the immune response of IECs.

  10. Stat3-dependent acute Rantes production in vascular smooth muscle cells modulates inflammation following arterial injury in mice

    PubMed Central

    Kovacic, Jason C.; Gupta, Rohit; Lee, Angela C.; Ma, Mingchao; Fang, Fang; Tolbert, Claire N.; Walts, Avram D.; Beltran, Leilani E.; San, Hong; Chen, Guibin; St. Hilaire, Cynthia; Boehm, Manfred

    2009-01-01

    Inflammation is a key component of arterial injury, with VSMC proliferation and neointimal formation serving as the final outcomes of this process. However, the acute events transpiring immediately after arterial injury that establish the blueprint for this inflammatory program are largely unknown. We therefore studied these events in mice and found that immediately following arterial injury, medial VSMCs upregulated Rantes in an acute manner dependent on Stat3 and NF-?B (p65 subunit). This led to early T cell and macrophage recruitment, processes also under the regulation of the cyclin-dependent kinase inhibitor p21Cip1. Unique to VSMCs, Rantes production was initiated by Tnf-?, but not by Il-6/gp130. This Rantes production was dependent on the binding of a p65/Stat3 complex to NF-?B–binding sites within the Rantes promoter, with shRNA knockdown of either Stat3 or p65 markedly attenuating Rantes production. In vivo, acute NF-?B and Stat3 activation in medial VSMCs was identified, with acute Rantes production after injury substantially reduced in Tnfa–/– mice compared with controls. Finally, we generated mice with SMC-specific conditional Stat3 deficiency and confirmed the Stat3 dependence of acute Rantes production by VSMCs. Together, these observations unify inflammatory events after vascular injury, demonstrating that VSMCs orchestrate the arterial inflammatory response program via acute Rantes production and subsequent inflammatory cell recruitment. PMID:20038813

  11. Raf Kinase Inhibitor Protein (RKIP) Blocks Signal Transducer and Activator of Transcription 3 (STAT3) Activation in Breast and Prostate Cancer

    PubMed Central

    Moen, Erika L.; Cross-Knorr, Sam; Brilliant, Kate; Bonavida, Benjamin; LaValle, Theresa; Yeung, Kam C.; Al-Mulla, Fahd; Chin, Eugene; Chatterjee, Devasis

    2014-01-01

    Raf kinase inhibitor protein (RKIP) is a member of the phosphatidylethanolamine-binding-protein (PEBP) family that modulates the action of many kinases involved in cellular growth, apoptosis, epithelial to mesenchymal transition, motility, invasion and metastasis. Previously, we described an inverse association between RKIP and signal transducers and activators of transcription 3 (STAT3) expression in gastric adenocarcinoma patients. In this study, we elucidated the mechanism by which RKIP regulates STAT3 activity in breast and prostate cancer cell lines. RKIP over expression inhibited c-Src auto-phosphorylation and activation, as well as IL-6-, JAK1 and 2-, and activated Raf-mediated STAT3 tyrosine and serine phosphorylation and subsequent activation. In MDA-231 breast cancer cells that stably over express RKIP, IL-6 treatment blocked STAT3 phosphorylation and transcriptional activation. Conversely, in RKIP knockdown MDA-231 cells: STAT3 phosphorylation and activation increased in comparison to parental MDA-231 cells. RKIP over expression resulted in constitutive physical interaction with STAT3 and blocked c-Src and STAT3 association. The treatment of DU145 prostate, but not PC3 prostate or MDA-231 breast, cancer cell lines with ENMD-1198 or MKC-1 dramatically increased expression of RKIP. Overexpression of RKIP sensitized PC3 and MDA-231 cells to MTI-induced apoptosis. Moreover, MTI treatment resulted in a decrease in Src-mediated STAT3 tyrosine phosphorylation and activation, an effect that was significantly enhanced by RKIP over expression. In stable RKIP over expressing MDA-231 cells, tumor xenograft growth induced by activated STAT3 is inhibited. RKIP synergizes with MTIs to induce apoptosis and inhibit STAT3 activation of breast and prostate cancer cells. RKIP plays a critical role in opposing the effects of pro-oncogenic STAT3 activation. PMID:24658061

  12. Germacrone induces apoptosis in human hepatoma HepG2 cells through inhibition of the JAK2/STAT3 signalling pathway.

    PubMed

    Liu, Yun-yi; Zheng, Qian; Fang, Bin; Wang, Wei; Ma, Feng-yun; Roshan, Sadia; Banafa, Amal; Chen, Ming-jie; Chang, Jun-li; Deng, Xiao-min; Li, Ke-xiu; Yang, Guang-xiao; He, Guang-yuan

    2013-06-01

    Previous studies have shown that STAT3 plays a vital role in the genesis and progression of cancer. In this study, we investigated the relationship between the JAK2/STAT3 signalling pathway and germacrone-induced apoptosis in HepG2 cells. HepG2 cells were incubated with germacrone for 24 h, the protein expression of p-STAT3, STAT3, p-JAK2 and JAK2 was detected by Western Blotting, and RT-PCR was used to determine the expression of STAT3, p53, Bcl-2 and Bax at transcriptional levels. Besides that, HepG2 cells were pre-treated with AG490 or IL-6 for 2 h, and then incubated with germacrone for 24 h. The expression of p-JAK2, JAK2, p-STAT3, STAT3, p53, Bax and Bcl-2 was detected by Western blotting. The activity of HepG2 cells was tested by MTT assay. The apoptosis of HepG2 cells and levels of reactive oxygen species (ROS) were flow cytometrically measured. The results showed that germacrone exposure decreased p-STAT3 and p-JAK2 and regulated expression of p53 and Bcl-2 family members at the same time. Moreover, IL-6 enhanced the activation of the JAK2/STAT3 signalling pathway and therefore attenuated the germacrone-induced apoptosis. Suppression of JAK2/STAT3 signalling pathway by AG490, an inhibitor of JAK2, resulted in apoptosis and an increase in ROS in response to germacrone exposure. We therefore conclude that germacrone induces apoptosis through the JAK2/STAT3 signalling pathway. PMID:23771657

  13. Ratios of Four STAT3 Splice Variants in Human Eosinophils and Diffuse Large B Cell Lymphoma Cells.

    PubMed

    Turton, Keren B; Annis, Douglas S; Rui, Lixin; Esnault, Stephane; Mosher, Deane F

    2015-01-01

    Signal transducer and activator of transcription 3 (STAT3) is a key mediator of leukocyte differentiation and proliferation. The 3' end of STAT3 transcripts is subject to two alternative splicing events. One results in either full-length STAT3? or in STAT3?, which lacks part of the C-terminal transactivation domain. The other is at a tandem donor (5') splice site and results in the codon for Ser-701 being included (S) or excluded (?S). Despite the proximity of Ser-701 to the site of activating phosphorylation at Tyr-705, ?S/S splicing has barely been studied. Sequencing of cDNA from purified eosinophils revealed the presence of four transcripts (S-?, ?S-?, S-?, and ?S-?) rather than the three reported in publically available databases from which ?S-? is missing. To gain insight into regulation of the two alternative splicing events, we developed a quantitative(q) PCR protocol to compare transcript ratios in eosinophils in which STAT3 is upregulated by cytokines, activated B cell diffuse large B cell Lymphoma (DLBCL) cells in which STAT3 is dysregulated, and in germinal center B cell-like DLBCL cells in which it is not. With the exception of one line of activated B cell DLCBL cells, the four variants were found in roughly the same ratios despite differences in total levels of STAT3 transcripts. S-? was the most abundant, followed by S-?. ?S-? and ?S-? together comprised 15.6±4.0 % (mean±SD, n=21) of the total. The percentage of STAT3? variants that were ?S was 1.5-fold greater than of STAT3? variants that were ?S. Inspection of Illumina's "BodyMap" RNA-Seq database revealed that the ?S variant accounts for 10-26 % of STAT3 transcripts across 16 human tissues, with less variation than three other genes with the identical tandem donor splice site sequence. Thus, it seems likely that all cells contain the S-?, ?S-?, S-?, and ?S-? variants of STAT3. PMID:25984943

  14. Ratios of Four STAT3 Splice Variants in Human Eosinophils and Diffuse Large B Cell Lymphoma Cells

    PubMed Central

    Turton, Keren B.; Annis, Douglas S.; Rui, Lixin; Esnault, Stephane; Mosher, Deane F.

    2015-01-01

    Signal transducer and activator of transcription 3 (STAT3) is a key mediator of leukocyte differentiation and proliferation. The 3' end of STAT3 transcripts is subject to two alternative splicing events. One results in either full-length STAT3? or in STAT3?, which lacks part of the C-terminal transactivation domain. The other is at a tandem donor (5') splice site and results in the codon for Ser-701 being included (S) or excluded (?S). Despite the proximity of Ser-701 to the site of activating phosphorylation at Tyr-705, ?S/S splicing has barely been studied. Sequencing of cDNA from purified eosinophils revealed the presence of four transcripts (S-?, ?S-?, S-?, and ?S-?) rather than the three reported in publically available databases from which ?S-? is missing. To gain insight into regulation of the two alternative splicing events, we developed a quantitative(q) PCR protocol to compare transcript ratios in eosinophils in which STAT3 is upregulated by cytokines, activated B cell diffuse large B cell Lymphoma (DLBCL) cells in which STAT3 is dysregulated, and in germinal center B cell-like DLBCL cells in which it is not. With the exception of one line of activated B cell DLCBL cells, the four variants were found in roughly the same ratios despite differences in total levels of STAT3 transcripts. S-? was the most abundant, followed by S-?. ?S-? and ?S-? together comprised 15.6±4.0 % (mean±SD, n=21) of the total. The percentage of STAT3? variants that were ?S was 1.5-fold greater than of STAT3? variants that were ?S. Inspection of Illumina’s “BodyMap” RNA-Seq database revealed that the ?S variant accounts for 10-26 % of STAT3 transcripts across 16 human tissues, with less variation than three other genes with the identical tandem donor splice site sequence. Thus, it seems likely that all cells contain the S-?, ?S-?, S-?, and ?S-? variants of STAT3. PMID:25984943

  15. Cell Surface GRP78 Accelerated Breast Cancer Cell Proliferation and Migration by Activating STAT3

    PubMed Central

    Yao, Xiaoli; Liu, Hua; Zhang, Xinghua; Zhang, Liang; Li, Xiang; Wang, Changhua; Sun, Shengrong

    2015-01-01

    High levels of cell surface glucose regulated protein 78 (sGRP78) have been implicated in cancer growth, survival, metastasis, and chemotherapy resistance. However, the underlying mechanism remains largely unknown. Here we report that the level of sGRP78 expression in human breast tumors gradually increases during cancer progression. Overexpression of GRP78 significantly enhanced its membrane distribution in human MCF-7 breast cancer cells, but had no effect on endoplasmic reticulum (ER) stress. High levels of sGRP78 facilitated cell proliferation and migration, as well as suppressed cell apoptosis. Neutralization of sGRP78 by a specific antibody against GRP78 alleviated sGRP78-induced cell growth and migration. Importantly, high phosphorylation levels of the signal transducer and activator of transcription 3 (STAT3) were found in human breast tumors that express sGRP78 and MCF-7 cells infected with adenovirus encoding human GRP78. Pretreatment with a GRP78 antibody suppressed STAT3 phosphorylation. Furthermore, genetic and pharmacological inhibition of STAT3 reversed the impacts of GRP78 on cell proliferation, apoptosis, and migration. These findings indicate that STAT3 mediates sGRP78-promoted breast cancer cell growth and migration. PMID:25973748

  16. STAT3 signaling contributes to the high effector activities of interleukin-15-derived dendritic cells

    PubMed Central

    Okada, Starlyn; Han, Shuhong; Patel, Ekta S; Yang, Li-Jun; Chang, Lung-Ji

    2015-01-01

    Dendritic cells (DCs) are important innate and adaptive immune effectors, and have a key role in antigen presentation and T-cell activation. Different lineages of DCs can be developed from hematopoietic progenitors following cytokine signaling, and the various lineages of DCs display distinct morphology, phenotype and functions. There has been limited information on differential cytokine-mediated molecular signaling in DCs. Analyses of surface molecules by flow cytometry and quantitative RNA profiling revealed differences between DCs derived from interleukin-4 (IL-4) versus IL-15 signaling, yet both lineages of DCs exhibited similar levels of surface molecules key to immune activation. Functional assays confirmed that IL-15-derived DCs elicited greater antigen-specific, primary and secondary CD8 and CD4 T-cell responses than did IL-4-derived DCs. Importantly, IL-15 DCs secreted substantial amounts of proinflammatory cytokines, including IL-6, interferon-? (IFN-?) and tumor necrosis factor-? (TNF?), which helped polarize a strong T-cell response. Assessment of signaling pathways revealed that IL-15 DCs exhibited a lower levels of activated signal transducer and activator of transcription 5 (STAT5), STAT6 and extracellular signal-regulated kinase 1/2 than IL-4 DCs, but after lipopolysaccharide (LPS)/TNF? treatment, the STAT3 and p38 mitogen-activated protein kinase (MAPK) activities were significantly enhanced in the IL-15 DCs. Surprisingly, contrary to the canonical IL-15-mediated STAT5 signaling pathway in lymphoid cells, IL-15 did not mediate a strong STAT5 or STAT3 activation in DCs. Further analysis using specific inhibitors to STAT3 and p38 MAPK pathways revealed that the STAT3 signaling, but not p38 MAPK signaling, contributed to IFN-? production in DCs. Therefore, while IL-15 does not promote the STAT signaling in DCs, the increased STAT3 activity after LPS/TNF? treatment of the IL-15 DCs has a key role in their high IFN-? effector activities. PMID:25582338

  17. Folic acid mediates activation of the pro-oncogene STAT3 via the Folate Receptor alpha.

    PubMed

    Hansen, Mariann F; Greibe, Eva; Skovbjerg, Signe; Rohde, Sarah; Kristensen, Anders C M; Jensen, Trine R; Stentoft, Charlotte; Kjær, Karina H; Kronborg, Camilla S; Martensen, Pia M

    2015-07-01

    The signal transducer and activator of transcription 3 (STAT3) is a well-described pro-oncogene found constitutively activated in several cancer types. Folates are B vitamins that, when taken up by cells through the Reduced Folate Carrier (RFC), are essential for normal cell growth and replication. Many cancer cells overexpress a glycophosphatidylinositol (GPI)-anchored Folate Receptor ? (FR?). The function of FR? in cancer cells is still poorly described, and it has been suggested that transport of folate is not its primary function in these cells. We show here that folic acid and folinic acid can activate STAT3 through FR? in a Janus Kinase (JAK)-dependent manner, and we demonstrate that gp130 functions as a transducing receptor for this signalling. Moreover, folic acid can promote dose dependent cell proliferation in FR?-positive HeLa cells, but not in FR?-negative HEK293 cells. After folic acid treatment of HeLa cells, up-regulation of the STAT3 responsive genes Cyclin A2 and Vascular Endothelial Growth Factor (VEGF) were verified by qRT-PCR. The identification of this FR?-STAT3 signal transduction pathway activated by folic and folinic acid contributes to the understanding of the involvement of folic acid in preventing neural tube defects as well as in tumour growth. Previously, the role of folates in these diseases has been attributed to their roles as one-carbon unit donors following endocytosis into the cell. Our finding that folic acid can activate STAT3 via FR? adds complexity to the established roles of B9 vitamins in cancer and neural tube defects. PMID:25841994

  18. SPARC expression induces cell cycle arrest via STAT3 signaling pathway in medulloblastoma cells

    SciTech Connect

    Chetty, Chandramu [Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, One Illini Drive, Peoria, IL-61605 (United States)] [Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, One Illini Drive, Peoria, IL-61605 (United States); Dontula, Ranadheer [Section of Hematology/Oncology, Department of Medicine, University of Illinois College of Medicine at Chicago, 840 South Wood Street, Suite 820-E, Chicago, IL-60612 (United States)] [Section of Hematology/Oncology, Department of Medicine, University of Illinois College of Medicine at Chicago, 840 South Wood Street, Suite 820-E, Chicago, IL-60612 (United States); Ganji, Purnachandra Nagaraju [Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, One Illini Drive, Peoria, IL-61605 (United States)] [Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, One Illini Drive, Peoria, IL-61605 (United States); Gujrati, Meena [Department of Pathology, University of Illinois College of Medicine at Peoria, One Illini Drive, Peoria, IL-61605 (United States)] [Department of Pathology, University of Illinois College of Medicine at Peoria, One Illini Drive, Peoria, IL-61605 (United States); Lakka, Sajani S., E-mail: slakka@uic.edu [Section of Hematology/Oncology, Department of Medicine, University of Illinois College of Medicine at Chicago, 840 South Wood Street, Suite 820-E, Chicago, IL-60612 (United States)

    2012-01-13

    Highlights: Black-Right-Pointing-Pointer Ectopic expression of SPARC impaired cell proliferation in medulloblastoma cells. Black-Right-Pointing-Pointer SPARC expression induces STAT3 mediated cell cycle arrest in medulloblastoma cells. Black-Right-Pointing-Pointer SPARC expression significantly inhibited pre-established tumor growth in nude-mice. -- Abstract: Dynamic cell interaction with ECM components has profound influence in cancer progression. SPARC is a component of the ECM, impairs the proliferation of different cell types and modulates tumor cell aggressive features. We previously reported that SPARC expression significantly impairs medulloblastoma tumor growth in vivo. In this study, we demonstrate that expression of SPARC inhibits medulloblastoma cell proliferation. MTT assay indicated a dose-dependent reduction in tumor cell proliferation in adenoviral mediated expression of SPARC full length cDNA (Ad-DsRed-SP) in D425 and UW228 cells. Flow cytometric analysis showed that Ad-DsRed-SP-infected cells accumulate in the G2/M phase of cell cycle. Further, immunoblot and immunoprecipitation analyses revealed that SPARC induced G2/M cell cycle arrest was mediated through inhibition of the Cyclin-B-regulated signaling pathway involving p21 and Cdc2 expression. Additionally, expression of SPARC decreased STAT3 phosphorylation at Tyr-705; constitutively active STAT3 expression reversed SPARC induced G2/M arrest. Ad-DsRed-SP significantly inhibited the pre-established orthotopic tumor growth and tumor volume in nude-mice. Immunohistochemical analysis of tumor sections from mice treated with Ad-DsRed-SP showed decreased immunoreactivity for pSTAT3 and increased immunoreactivity for p21 compared to tumor section from mice treated with mock and Ad-DsRed. Taken together our studies further reveal that STAT3 plays a key role in SPARC induced G2/M arrest in medulloblastoma cells. These new findings provide a molecular basis for the mechanistic understanding of the effects of SPARC on medulloblastoma tumor cell proliferation.

  19. Stat3 directly controls the expression of Tbx5, Nkx2.5, and GATA4 and is essential for cardiomyocyte differentiation of P19CL6 cells.

    PubMed

    Snyder, Marylynn; Huang, Xin-Yun; Zhang, J Jillian

    2010-07-30

    The transcription factor Stat3 (signal transducer and activator of transcription 3) mediates many physiological processes, including embryogenesis, stem cell self-renewal, and postnatal survival. In response to gp130 receptor activation, Stat3 becomes phosphorylated by the receptor-associated Janus kinase, forms dimers, and enters the nucleus where it binds to Stat3 target genes and regulates their expression. In this report, we demonstrate that Stat3 binds directly to the promoters and regulates the expression of three genes that are essential for cardiac differentiation: Tbx5, Nkx2.5, and GATA4. We further demonstrate that Tbx5, Nkx2.5, and GATA4 expression is dependent on Stat3 in response to ligand treatment and during ligand-independent differentiation of P19CL6 cells into cardiomyocytes. Finally, we show that Stat3 is necessary for the differentiation of P19CL6 cells into beating cardiomyocytes. All together, these results demonstrate that Stat3 is required for the differentiation of cardiomyocytes through direct transcriptional regulation of Tbx5, Nkx2.5, and GATA4. PMID:20522556

  20. Brassinin inhibits STAT3 signaling pathway through modulation of PIAS-3 and SOCS-3 expression and sensitizes human lung cancer xenograft in nude mice to paclitaxel

    PubMed Central

    Lee, Jong Hyun; Kim, Chulwon; Sethi, Gautam; Ahn, Kwang Seok

    2015-01-01

    Persistent phosphorylation of signal transducers and activators of transcription 3 (STAT3) is frequently observed in tumor cells. We found that brassinin (BSN) suppressed both constitutive and IL-6-inducible STAT3 activation in lung cancer cells. Moreover, BSN induced PIAS-3 protein and mRNA, whereas the expression of SOCS-3 was reduced. Knockdown of PIAS-3 by small interfering RNA prevented inhibition of STAT3 and cytotoxicity by BSN. Overexpression of SOCS-3 in BSN-treated cells increased STAT3 phosphorylation and cell viability. BSN down-regulated STAT3-regulated gene products, inhibited proliferation, invasion, as well as induced apoptosis. Most importantly, when administered intraperitoneally, combination of BSN and paclitaxel significantly decreased the tumor development in a xenograft lung cancer mouse model associated with down-modulation of phospho-STAT3, Ki-67 and CD31. We suggest that BSN inhibits STAT3 signaling through modulation of PIAS-3 and SOCS-3, thereby attenuating tumor growth and increasing sensitivity to paclitaxel. PMID:25788267

  1. RKIP phosphorylation and STAT3 activation is inhibited by oxaliplatin and camptothecin and are associated with poor prognosis in stage II colon cancer patients

    PubMed Central

    2013-01-01

    Background A major obstacle in treating colorectal cancer (CRC) is the acquired resistance to chemotherapeutic agents. An important protein in the regulation of cancer cell death and clinical outcome is Raf kinase inhibitor protein (RKIP). In contrast, activated signal transducer and activator of transcription 3 (STAT3) is a protein that promotes tumor cell survival by inhibiting apoptosis and has an important role in cancer progression in many of cancer types. The aim of this study was to evaluate the regulation of RKIP and STAT3 after treatment with clinically relevant chemotherapeutic agents (camptothecin (CPT) and oxaliplatin (OXP)) and the cytokine interleukin-6 (IL-6) in HCT116 colon cancer cells as well as evaluate the association between RKIP and STAT3 with clinical outcome of Stage II colon cancer patients. Methods HCT-116 colon cancer cells were treated with CPT, OXP, and IL-6 separately or in combination in a time and dose-dependent manner and examined for phosphorylated and non-phosphorylated RKIP and STAT3 via Western blot analysis. STAT3 transcriptional activity was measured via a luciferase reporter assay in HCT116 cells treated with CPT, IL-6 or transfected with JAK 1, 2 separately or in combination. We extended these observations and determined STAT3 and RKIP/ pRKIP in tumor microarrays (TMA) in stage II colon cancer patients. Results We demonstrate IL-6-mediated activation of STAT3 occurs in conjunction with the phosphorylation of RKIP in vitro in human colon cancer cells. OXP and CPT block IL-6 mediated STAT3 activation and RKIP phosphorylation via the inhibition of the interaction of STAT3 with gp130. We determined that STAT3 and nuclear pRKIP are significantly associated with poor patient prognosis in stage II colon cancer patients. Conclusions In the analysis of tumor samples from stage II colon cancer patients and the human colon carcinoma cell line HCT116, pRKIP and STAT3, 2 proteins potentially involved in the resistance to conventional treatments were detected. The phosphorylation of pRKIP and STAT3 are induced by the cytokine IL-6 and suppressed by the chemotherapeutic drugs CPT and OXP. Therefore, these results suggest that STAT3 and pRKIP may serve as prognostic biomarkers in stage II colon cancer patients and may improve chemotherapy. PMID:24098947

  2. Deletion of Intestinal Epithelial Cell STAT3 Promotes T Lymphocyte STAT3 Activation and Chronic Colitis Following Acute Dextran Sodium Sulfate Injury in Mice

    PubMed Central

    Willson, Tara A.; Jurickova, Ingrid; Collins, Margaret; Denson, Lee A.

    2015-01-01

    BACKGROUND Intestinal epithelial cell (IEC) Stat3 is required for wound healing following acute Dextran Sodium Sulfate (DSS) injury. We hypothesized that loss of IEC STAT3 would promote the development of chronic colitis following acute DSS injury. METHODS Colitis was induced in IEC-specific Stat3 deficient mice (Stat3?IEC) and littermate controls (Stat3Flx/Flx) with 4%DSS for 7 days, followed by water consumption for 21 days. Epithelial and immune mediators and severity of colitis were determined. RESULTS Survival, colon length, and histologic injury were significantly worse at day 28 in Stat3?IEC mice. IEC proliferation and apoptosis did not vary by genotype at day 14 or day 28. The colonic lamina propria frequency of pSTAT3+ cells was increased at day 28 and correlated with histologic injury in Stat3?IEC mice. The frequency of colonic F480+pSTAT3+ macrophages and CD3+pSTAT3+ T-lymphocytes were increased in Stat3?IEC mice as compared to Stat3Flx/Flx controls. In Stat3?IEC mice, colonic expression of Stat3 target genes Reg3? and Reg3? which mediate epithelial restitution were significantly decreased, while expression of IL-17a, IFN?, CXCL2, CXCL10, and CCL2 were significantly increased and correlated with the increase in histologic severity at Day 28(p<.05). IL-17a expression also correlated with the increased lamina propria frequency of CD3+pSTAT3+ T-lymphocytes. CONCLUSIONS Loss of intestinal epithelial Stat3 leads to more severe chronic inflammation following acute injury which is not accounted for by a sustained defect in epithelial proliferation or apoptosis 7 or 21 days after one cycle of DSS but rather defective REG3 expression and expansion of pSTAT3+ lymphocytes and IL-17a expression. PMID:23429443

  3. RECK controls breast cancer metastasis by modulating a convergent, STAT3-dependent neoangiogenic switch.

    PubMed

    Walsh, L A; Roy, D M; Reyngold, M; Giri, D; Snyder, A; Turcan, S; Badwe, C R; Lyman, J; Bromberg, J; King, T A; Chan, T A

    2015-04-23

    Metastasis is the primary cause of cancer-related death in oncology patients. A comprehensive understanding of the molecular mechanisms that cancer cells usurp to promote metastatic dissemination is critical for the development and implementation of novel diagnostic and treatment strategies. Here we show that the membrane protein RECK (Reversion-inducing cysteine-rich protein with kazal motifs) controls breast cancer metastasis by modulating a novel, non-canonical and convergent signal transducer and activator of transcription factor 3 (STAT3)-dependent angiogenic program. Neoangiogenesis and STAT3 hyperactivation are known to be fundamentally important for metastasis, but the root molecular initiators of these phenotypes are poorly understood. Our study identifies loss of RECK as a critical and previously unknown trigger for these hallmarks of metastasis. Using multiple xenograft mouse models, we comprehensively show that RECK inhibits metastasis, concomitant with a suppression of neoangiogenesis at secondary sites, while leaving primary tumor growth unaffected. Further, with functional genomics and biochemical dissection we demonstrate that RECK controls this angiogenic rheostat through a novel complex with cell surface receptors to regulate STAT3 activation, cytokine signaling, and the induction of both vascular endothelial growth factor and urokinase plasminogen activator. In accordance with these findings, inhibition of STAT3 can rescue this phenotype both in vitro and in vivo. Taken together, our study uncovers, for the first time, that RECK is a novel regulator of multiple well-established and robust mediators of metastasis; thus, RECK is a keystone protein that may be exploited in a clinical setting to target metastatic disease from multiple angles. PMID:24931164

  4. Cell-to-cell adhesion modulates Stat3 activity in normal and breast carcinoma cells

    Microsoft Academic Search

    Adina Vultur; Jun Cao; Rozanne Arulanandam; James Turkson; Richard Jove; Peter Greer; Andrew Craig; Bruce Elliott; Leda Raptis

    2004-01-01

    Stat3 (signal transducer and activator of transcription-3) activity is required for transformation by a number of oncogenes, while a constitutively active form of Stat3 alone is sufficient to induce neoplastic transformation. Although in most instances Stat3 is growth-promoting, the impact of cell density on Stat3 activation status and the biological importance of Stat3 during growth arrest have not been characterized.

  5. STAT3 inhibitor WP1066 as a novel therapeutic agent for bCCI neuropathic pain rats.

    PubMed

    Xue, Zhao-Jing; Shen, Le; Wang, Zhi-Yao; Hui, Shang-Yi; Huang, Yu-Guang; Ma, Chao

    2014-10-01

    Activation of signal transducer and activator of transcription-3 (STAT3) is suggested to be critically involved in the development of chronic pain, but the complex regulation of STAT3-dependent pathway and the functional significance of inhibiting this pathway during the development of neuropathic pain remain elusive. To evaluate the contribution of the JAK2/STAT3 pathway to neuropathic pain and the potentiality of this pathway as a novel therapeutic target, we examined the effects of the STAT3 inhibitor WP1066 by intrathecal administration in a rat model of bilateral chronic constriction injury (bCCI). The pain behavior tests were performed before the surgery and on postoperative day 3, 7, 14 and 21. L4-L6 dorsal spinal cord were harvested at each time point. Both RT-PCR and Western blot were performed to evaluate the activation of JAK2/STAT3 pathway. To observe the influence of WP1066 on neuropathic pain and its molecular mechanism, WP1066 (10 ?l, 10 mmol/L in DMSO) or the same capacity of DMSO as the control were applied through the intrathecal tube on the day before bCCI surgery, and on the postoperative day 3 and 5. Behavioral tests were performed to observe the therapeutic effect on mechanical, thermal and cold hyperalgesia. L4-L6 dorsal spinal cord was harvested on postoperative day fourteen, followed by RT-PCR and Western blot evaluation of the JAK2/STAT3 pathway activation. The mechanical, thermal and cold hyperalgesia of the bCCI rats were significantly decreased when compared with the Sham or the Naïve group at each postoperative time point (P<0.05). JAK2 mRNA and STAT3 mRNA were significantly increased in the bCCI rats, accompanied by SOCS3 mRNA with a similar tendency. Western blot analysis showed that JAK2 and phosphorylated STAT3 increased significantly since 3 days after bCCI. JAK2 peaked on postoperative day 14 while phosphorylated STAT3 peaked on postoperative day 7 and gradually decreased thereafter and SOCS3?s peak level on postoperative day 3. When WP1066 were administered intrathecally, the pain behaviors of the bCCI rats were significantly improved (P<0.05). WP1066 also inhibited the mRNA level of JAK2, STAT3 and SOCS3 in bCCI rats significantly, together with the protein level of JAK2, phosphorylated STAT3 and SOCS3 on postoperative day 14 as well. Our results found that the JAK2/STAT3 pathway in the spinal cord dorsal horn was significantly activated in the bCCI neuropathic pain rats. WP1066, which inhibited the STAT3 pathway specifically, could partially alleviate the pain behavior of the bCCI rats. So it may serve as a novel therapeutic strategy against neuropathic pain. PMID:25084036

  6. Binding Modes of Peptidomimetics Designed to Inhibit STAT3

    PubMed Central

    Dhanik, Ankur; McMurray, John S.; Kavraki, Lydia E.

    2012-01-01

    STAT3 is a transcription factor that has been found to be constitutively activated in a number of human cancers. Dimerization of STAT3 via its SH2 domain and the subsequent translocation of the dimer to the nucleus leads to transcription of anti-apoptotic genes. Prevention of the dimerization is thus an attractive strategy for inhibiting the activity of STAT3. Phosphotyrosine-based peptidomimetic inhibitors, which mimic pTyr-Xaa-Yaa-Gln motif and have strong to weak binding affinities, have been previously investigated. It is well-known that structures of protein-inhibitor complexes are important for understanding the binding interactions and designing stronger inhibitors. Experimental structures of inhibitors bound to the SH2 domain of STAT3 are, however, unavailable. In this paper we describe a computational study that combined molecular docking and molecular dynamics to model structures of 12 peptidomimetic inhibitors bound to the SH2 domain of STAT3. A detailed analysis of the modeled structures was performed to evaluate the characteristics of the binding interactions. We also estimated the binding affinities of the inhibitors by combining MMPB/GBSA-based energies and entropic cost of binding. The estimated affinities correlate strongly with the experimentally obtained affinities. Modeling results show binding modes that are consistent with limited previous modeling studies on binding interactions involving the SH2 domain and phosphotyrosine(pTyr)-based inhibitors. We also discovered a stable novel binding mode that involves deformation of two loops of the SH2 domain that subsequently bury the C-terminal end of one of the stronger inhibitors. The novel binding mode could prove useful for developing more potent inhibitors aimed at preventing dimerization of cancer target protein STAT3. PMID:23251591

  7. ?-Mangostin suppresses human gastric adenocarcinoma cells in vitro via blockade of Stat3 signaling pathway

    PubMed Central

    Shan, Tao; Cui, Xi-juan; Li, Wei; Lin, Wan-run; Lu, Hong-wei; Li, Yi-ming; Chen, Xi; Wu, Tao

    2014-01-01

    Aim: To investigate the anti-tumor effects of ?-mangostin, a major xanthone identified in the pericarp of mangosteen (Garcinia mangostana Linn), against human gastric adenocarcinoma cells in vitro, and the mechanisms of the effects. Methods: Human gastric adenocarcinoma cell lines BGC-823 and SGC-7901 were treated with ?-mangostin. The cell viability was measured with MTT assay, and cell apoptosis was examined using flow cytometry and TUNEL assay. The expression of the relevant proteins was detected using Western blot. Results: Treatment with ?-mangostin (3–10 ?g/mL) inhibited the viability of both BGC-823 and SGC-7901 cells in dose- and time-manners. Furthermore, ?-mangostin (7 ?g/mL) time-dependently increased the apoptosis index of the cancer cells, reduced the mitochondrial membrane potential of the cancer cells, and significantly increased the release of cytochrome c and AIF into cytoplasm. Moreover, the ?-mangostin treatment markedly suppressed the constitutive Stat3 protein activation, and Stat3-regulated Bcl-xL and Mcl-1 protein levels in the cancer cells. Conclusion: The anti-tumor effects of ?-mangostin against human gastric adenocarcinoma cells in vitro can be partly attributed to blockade of Stat3 signaling pathway. PMID:24976157

  8. Mogrol represents a novel leukemia therapeutic, via ERK and STAT3 inhibition

    PubMed Central

    Liu, Can; Zeng, Yan; Dai, Long-Hai; Cai, Tian-Yu; Zhu, Yue-Ming; Dou, De-Quan; Ma, Lan-Qing; Sun, Yuan-Xia

    2015-01-01

    Unlike solid tumors, the primary strategy for leukemia treatment is chemotherapy. However, leukemia chemotherapy is associated with adverse drug effects and drug resistance. Therefore, it is imperative to identify novel agents that effectively treat leukemia while minimizing adverse effects. The Raf/MEK/extracellular regulated kinase (ERK) and signal transducer and activator of transcription 3 (STAT3) pathways have been implicated in leukemia carcinogenesis, and provide novel molecular targets for therapeutic intervention in cancer. Mogrol, a biometabolite of mogrosides found in Siraitia grosvenorii, has exhibited anti-cancer activities; however, the underlying mechanism of this effect remains unclear. To clarify its anti-cancer activity and mechanism of action, we treated K562 leukemia cells with mogrol. Mogrol suppressed leukemia cell growth via inhibition of the ERK1/2 and STAT3 pathways, in particular, through the suppression of p-ERK1/2 and p-STAT3. Inhibition of these pathways suppressed Bcl-2 expression, thereby inducing K562 cell apoptosis. Furthermore, mogrol enhanced p21 expression, resulting in G0/G1 cell cycle arrest. The findings provide new perspectives regarding the role of mogrol in leukemia treatment.

  9. Acyloxy nitroso compounds inhibit LIF signaling in endothelial cells and cardiac myocytes: evidence that STAT3 signaling is redox-sensitive.

    PubMed

    Zgheib, Carlos; Kurdi, Mazen; Zouein, Fouad A; Gunter, Barak W; Stanley, Brian A; Zgheib, Joe; Romero, Damian G; King, S Bruce; Paolocci, Nazareno; Booz, George W

    2012-01-01

    We previously showed that oxidative stress inhibits leukemia inhibitory factor (LIF) signaling by targeting JAK1, and the catalytic domains of JAK 1 and 2 have a cysteine-based redox switch. Thus, we postulated that the NO sibling and thiophylic compound, nitroxyl (HNO), would inhibit LIF-induced JAK-STAT3 activation. Pretreatment of human microvascular endothelial cells (HMEC-1) or neonatal rat cardiomyocytes with the HNO donors Angeli's salt or nitrosocyclohexyl acetate (NCA) inhibited LIF-induced STAT3 activation. NCA pretreatment also blocked the induction of downstream inflammatory genes (e.g. intercellular adhesion molecule 1, CCAAT/enhancer binding protein delta). The related 1-nitrosocyclohexyl pivalate (NCP; not a nitroxyl donor) was equally effective in inhibiting STAT3 activation, suggesting that these compounds act as thiolate targeting electrophiles. The JAK1 redox switch is likely not a target of acyloxy nitroso compounds, as NCA had no effect on JAK1 catalytic activity and only modestly affected JAK1-induced phosphorylation of the LIF receptor. However, pretreatment of recombinant human STAT3 with NCA or NCP reduced labeling of free sulfhydryl residues. We show that NCP in the presence of diamide enhanced STAT3 glutathionylation and dimerization in adult mouse cardiac myocytes and altered STAT3 under non-reducing conditions. Finally, we show that monomeric STAT3 levels are decreased in the G?q model of heart failure in a redox-sensitive manner. Altogether, our evidence indicates that STAT3 has redox-sensitive cysteines that regulate its activation and are targeted by HNO donors and acyloxy nitroso compounds. These findings raise the possibility of new therapeutic strategies to target STAT3 signaling via a redox-dependent manner, particularly in the context of cardiac and non-cardiac diseases with prominent pro-inflammatory signaling. PMID:22905257

  10. Acyloxy Nitroso Compounds Inhibit LIF Signaling in Endothelial Cells and Cardiac Myocytes: Evidence That STAT3 Signaling Is Redox-Sensitive

    PubMed Central

    Zgheib, Carlos; Kurdi, Mazen; Zouein, Fouad A.; Gunter, Barak W.; Stanley, Brian A.; Zgheib, Joe; Romero, Damian G.; King, S. Bruce; Paolocci, Nazareno; Booz, George W.

    2012-01-01

    We previously showed that oxidative stress inhibits leukemia inhibitory factor (LIF) signaling by targeting JAK1, and the catalytic domains of JAK 1 and 2 have a cysteine-based redox switch. Thus, we postulated that the NO sibling and thiophylic compound, nitroxyl (HNO), would inhibit LIF-induced JAK-STAT3 activation. Pretreatment of human microvascular endothelial cells (HMEC-1) or neonatal rat cardiomyocytes with the HNO donors Angeli’s salt or nitrosocyclohexyl acetate (NCA) inhibited LIF-induced STAT3 activation. NCA pretreatment also blocked the induction of downstream inflammatory genes (e.g. intercellular adhesion molecule 1, CCAAT/enhancer binding protein delta). The related 1-nitrosocyclohexyl pivalate (NCP; not a nitroxyl donor) was equally effective in inhibiting STAT3 activation, suggesting that these compounds act as thiolate targeting electrophiles. The JAK1 redox switch is likely not a target of acyloxy nitroso compounds, as NCA had no effect on JAK1 catalytic activity and only modestly affected JAK1-induced phosphorylation of the LIF receptor. However, pretreatment of recombinant human STAT3 with NCA or NCP reduced labeling of free sulfhydryl residues. We show that NCP in the presence of diamide enhanced STAT3 glutathionylation and dimerization in adult mouse cardiac myocytes and altered STAT3 under non-reducing conditions. Finally, we show that monomeric STAT3 levels are decreased in the G?q model of heart failure in a redox-sensitive manner. Altogether, our evidence indicates that STAT3 has redox-sensitive cysteines that regulate its activation and are targeted by HNO donors and acyloxy nitroso compounds. These findings raise the possibility of new therapeutic strategies to target STAT3 signaling via a redox-dependent manner, particularly in the context of cardiac and non-cardiac diseases with prominent pro-inflammatory signaling. PMID:22905257

  11. The synthetic pentasaccharide fondaparinux attenuates myocardial ischemia-reperfusion injury in rats via STAT-3.

    PubMed

    Macchi, Laurent; Moussa, Walid Ben; Guillou, Sophie; Tamareille, Sophie; Lamon, Delphine; Prunier, Delphine; Prunier, Fabrice

    2014-02-01

    Acute myocardial infarction is a leading cause of mortality and morbidity worldwide. Although essential for successful recovery, myocardium reperfusion is associated with reperfusion injury. Two major cell survival signaling cascades are known to be protective against ischemia-reperfusion (I/R) injury: the reperfusion injury salvage kinase, including Akt, extracellular signal-regulated kinase 1/2, and the downstream target GSK-3?, and the survivor activating factor enhancement, which involves STAT-3. Pharmacologic inhibition of factor Xa has been shown to attenuate I/R injury, but the cellular mechanism is poorly understood. Our aim was to determine the role of whole blood in fondaparinux (FDX)-induced cardioprotection and the involvement of reperfusion injury salvage kinase and survivor activating factor enhancement pathways. We investigated FDX ability to prevent in vivo I/R injury using a transient coronary ligation rat model and ex vivo using a model of crystalloid-perfused isolated rat heart. In both models, infarct size was assessed after 120 min of reperfusion. Myocardial tissues were collected after 15 and 30 min of reperfusion for Western blot analysis. In vivo, FDX decreased infarct size by 29% and induced significant STAT-3 and GSK-3? phosphorylation in comparison to controls. Adding AG490, an inhibitor of JAK/STAT pathway, before I/R, prevented STAT-3 phosphorylation and abolished FDX-induced cardioprotection. On the contrary, FDX did not have an effect on infarct size or hemodynamic parameters in the isolated-heart model. Fondaparinux decreased I/R injury in vivo, but not in a crystalloid-perfused isolated heart. Under our experimental conditions, FDX required whole blood to be protective, and this beneficial effect was mediated through STAT-3 phosphorylation. PMID:24300830

  12. A20 Promotes Liver Regeneration by Decreasing SOCS3 Expression to Enhance IL-6/STAT3 Proliferative Signals

    PubMed Central

    da Silva, Cleide G.; Studer, Peter; Skroch, Marco; Mahiou, Jerome; Minussi, Darlan C.; Peterson, Clayton R.; Wilson, Suzhuei W.; Patel, Virendra I.; Ma, Averil; Csizmadia, Eva; Ferran, Christiane

    2013-01-01

    Liver regeneration is of major clinical importance in the setting of liver injury, resection, and transplantation. A20, a potent anti-inflammatory and NF-?B inhibitory protein, has established pro-proliferative properties in hepatocytes, in part through decreasing expression of the Cyclin Dependent Kinase Inhibitor, p21. Both C-terminal (7-Zinc fingers; 7Zn) and N-terminal (Nter) domains of A20 were required to decrease p21 and inhibit NF-?B. However, both independently increased hepatocyte proliferation, suggesting that additional mechanisms contributed to the pro-proliferative function of A20 in hepatocytes. We ascribed one of A20’s pro-proliferative mechanisms to increased and sustained IL-6 induced STAT3 phosphorylation, as a result of decreased hepatocyte expression of the negative regulator of IL-6 signaling, SOCS3. This novel A20 function segregates with its 7Zn not Nter domain. Conversely, total and partial loss of A20 in hepatocytes increased SOCS3 expression, hampering IL-6-induced STAT3 phosphorylation. Following liver resection in mice pro-proliferative targets downstream of IL-6/STAT3 signaling were increased by A20 overexpression and decreased by A20 knockdown. In contrast, IL-6/STAT3 pro-inflammatory targets were increased in A20 deficient livers, and decreased or unchanged in A20 overexpressing livers. Upstream of SOCS3, levels of its microRNA regulator miR203 were significantly decreased in A20-deficient livers. Altogether these results demonstrate that A20 enhances IL-6/STAT3 pro-proliferative signals in hepatocytes by down-regulating SOCS3, likely through a miR203-dependent manner. This finding together with A20 reducing the levels of the potent cell cycle brake p21 establishes its pro-proliferative properties in hepatocytes and prompts the pursuit of A20-based therapies to promote liver regeneration and repair. PMID:23238769

  13. Diminished allergic disease in patients with STAT3 mutations reveals a role for STAT3 signaling in mast cell degranulation

    PubMed Central

    Siegel, Andrea M.; Stone, Kelly D.; Cruse, Glenn; Lawrence, Monica G.; Olivera, Ana; Jung, Mi-yeon; Barber, John S.; Freeman, Alexandra F.; Holland, Steven M.; O’Brien, Michelle; Jones, Nina; Wisch, Laura B.; Kong, Heidi H.; Desai, Avanti; Farber, Orly; Gilfillan, Alasdair M.; Rivera, Juan; Milner, Joshua D.

    2013-01-01

    Background Severe atopic conditions associated with elevated serum IgE are heterogeneous with few known causes. Nearly every patient with autosomal-dominant hyper-IgE syndrome (AD-HIES) due to signal transducer and activator of transcription 3 (STAT3) mutations has a history of eczematous dermatitis and elevated IgE; however, clinical atopy has never been systematically studied. Objective Understanding of genetic determinants of allergic disease may lead to novel therapies in controlling allergic disease. Methods We conducted clinical evaluation of the rates of food allergies and anaphylaxis in patients with AD-HIES, a cohort of patients with no STAT3 mutation but with similar histories of elevated IgE and atopic dermatitis, and healthy volunteers with no history of atopy. Morphine skin prick testing, ImmunoCAP assays for allergen-specific IgE, and basophil activation were measured. A model of systemic anaphylaxis was studied in transgenic mice carrying an AD-HIES mutation. STAT3 was silenced in LAD2 and primary human mast cells to study the role of STAT3 in signaling and degranulation after IgE cross-linking. Results Food allergies and anaphylaxis were markedly diminished in patients with AD-HIES compared with a cohort of patients with no STAT3 mutation but with similar histories of elevated IgE and atopic dermatitis. Morphine skin prick testing and basophil activation were diminished in patients with AD-HIES, whereas mice carrying an AD-HIES mutation were hyporesponsive to systemic anaphylaxis models. Rapid mast cell STAT3 serine727 phosphorylation was noted after IgE cross-linking, and inhibition of STAT3 signaling in mast cells lead to impaired Fc?RI-mediated proximal and distal signaling, as well as reduced degranulation. Conclusion This study serves as an example for how mutations in specific atopic pathways can lead to discrete allergic phenotypes, encompassing increased risk of some phenotypes but a relative protection from others. PMID:24184145

  14. 6-Shogaol exerts anti-proliferative and pro-apoptotic effects through the modulation of STAT3 and MAPKs signaling pathways.

    PubMed

    Kim, Sung-Moo; Kim, Chulwon; Bae, Hang; Lee, Jong Hyun; Baek, Seung Ho; Nam, Dongwoo; Chung, Won-Seok; Shim, Bum Sang; Lee, Seok-Geun; Kim, Sung-Hoon; Sethi, Gautam; Ahn, Kwang Seok

    2014-06-24

    6-shogaol (6SG), one of active ingredients in ginger (Zingiber officinale), is known to exhibit anti-proliferative, anti-metastatic, and pro-apoptotic activities through a mechanism that is not fully elucidated. Because the aberrant activation of STAT3 and MAPKs have been associated with regulation of proliferation, invasion, and metastasis of tumors, we hypothesized that 6SG modulates the activation of STAT3 and MAPKs activation in tumor cells. We found that 6SG strongly inhibited constitutive phosphorylation of STAT3 through inhibition of the activation of upstream JAK2 and c-Src kinases and nuclear translocation of STAT3 on both MDA-MB231 and DU145 cells. Also, 6SG caused the activation of JNK, p38 MAPK, and ERK. Inhibition of ROS generation by N-acetylcysteine (NAC) significantly prevented 6SG-induced apoptosis. 6SG induced apoptosis as characterized by cleavage of PARP, accumulation of cells in subG1 phase, positive Annexin V binding, down-regulation of STAT3-regulated proteins, and activation of caspase-8, -9, -3 in both MDA-MB231 cells. Compared with other analogues of 6SG, such as 6-gingerol (6G), 8-gingerol (8G), and 10-gingerol (10G), 6SG was found to be the most potent blocker of STAT3 activation. We observed that the administration of 6SG alone significantly suppressed the growth of the tumor. As compared to the vehicle control, 6SG also suppressed the expression of STAT3-regulated gene products such as Bcl-2, Bcl-xL, and Survivin in tumor tissues. Overall, these findings suggest that 6SG can interfere with multiple signaling cascades involved in tumorigenesis and can be used as a potential therapeutic candidate for both the prevention and treatment of cancer. © 2014 Wiley Periodicals, Inc. PMID:24962868

  15. 4-Phenylbutyrate stimulates Hsp70 expression through the Elp2 component of elongator and STAT-3 in cystic fibrosis epithelial cells.

    PubMed

    Suaud, Laurence; Miller, Katelyn; Panichelli, Ashley E; Randell, Rachel L; Marando, Catherine M; Rubenstein, Ronald C

    2011-12-30

    Sodium 4-phenylbutyrate (4PBA) corrects trafficking of ?F508-CFTR in Cystic Fibrosis (CF) epithelia, which is hypothesized to, at least in part, result from increased expression of Hsp70 (stress-induced 70 kDa heat shock protein). To identify other 4PBA-regulated proteins that may promote correction of ?F508 trafficking, we performed differential display RT-PCR on mRNA from IB3-1 CF bronchiolar epithelial cells treated for 0-24 h with 1 mM 4PBA. In this screen, a STAT-3 (signal transducer and activator of transcription-3)-interacting protein, StIP-1 that regulates STAT-3 activation had transiently increased expression. StIP-1 is identical to Elongator protein 2 (Elp2), a component of the Elongator complex that regulates RNA polymerase II. Previous studies have suggested that Elongator regulates Hsp70 mRNA transcription, and that the Hsp70 promoter contains functional STAT-3-binding sites. We therefore tested the hypothesis that 4PBA increases Hsp70 expression by an Elongator- and STAT-3-dependent mechanism. 4PBA treatment of IB3-1 CF bronchiolar epithelial cells caused transiently increased expression of Hsp70 protein, as well as Elp2 protein and mRNA. Elp2 depletion by transfection of small interfering RNAs, reduced both Elp2 and Hsp70 protein expression. 4PBA also caused transient activation of STAT-3, and increased abundance of nuclear proteins that bind to the STAT-3-responsive element of the Hsp70 promoter. Luciferase reporter assays demonstrated that both Elp2 overexpression and 4PBA increase Hsp70 promoter activity, while Elp2 depletion blocked the ability of 4PBA to stimulate Hsp70 promoter activity. Together, these data suggest that Elp2 and STAT-3 mediate, at least in part, the stimulation of Hsp70 expression by 4PBA. PMID:22069317

  16. Stat3 promotes IL-10 expression in lupus T cells through trans-activation and chromatin remodeling

    PubMed Central

    Hedrich, Christian M.; Rauen, Thomas; Apostolidis, Sokratis A.; Grammatikos, Alexandros P.; Rodriguez Rodriguez, Noe; Ioannidis, Christina; Kyttaris, Vasileios C.; Crispin, Jose C.; Tsokos, George C.

    2014-01-01

    The immune-regulatory cytokine IL-10 plays a central role during innate and adaptive immune responses. IL-10 is elevated in the serum and tissues of patients with systemic lupus erythematosus (SLE), an autoimmune disorder characterized by autoantibody production, immune-complex formation, and altered cytokine expression. Because of its B cell-promoting effects, IL-10 may contribute to autoantibody production and tissue damage in SLE. We aimed to determine molecular events governing T cell-derived IL-10 expression in health and disease. We link reduced DNA methylation of the IL10 gene with increased recruitment of Stat family transcription factors. Stat3 and Stat5 recruitment to the IL10 promoter and an intronic enhancer regulate gene expression. Both Stat3 and Stat5 mediate trans-activation and epigenetic remodeling of IL10 through their interaction with the histone acetyltransferase p300. In T cells from SLE patients, activation of Stat3 is increased, resulting in enhanced recruitment to regulatory regions and competitive replacement of Stat5, subsequently promoting IL-10 expression. A complete understanding of the molecular events governing cytokine expression will provide new treatment options in autoimmune disorders, including SLE. The observation that altered activation of Stat3 influences IL-10 expression in T cells from SLE patients offers molecular targets in the search for novel target-directed treatment options. PMID:25187566

  17. Stat3 promotes IL-10 expression in lupus T cells through trans-activation and chromatin remodeling.

    PubMed

    Hedrich, Christian M; Rauen, Thomas; Apostolidis, Sokratis A; Grammatikos, Alexandros P; Rodriguez Rodriguez, Noe; Ioannidis, Christina; Kyttaris, Vasileios C; Crispin, Jose C; Tsokos, George C

    2014-09-16

    The immune-regulatory cytokine IL-10 plays a central role during innate and adaptive immune responses. IL-10 is elevated in the serum and tissues of patients with systemic lupus erythematosus (SLE), an autoimmune disorder characterized by autoantibody production, immune-complex formation, and altered cytokine expression. Because of its B cell-promoting effects, IL-10 may contribute to autoantibody production and tissue damage in SLE. We aimed to determine molecular events governing T cell-derived IL-10 expression in health and disease. We link reduced DNA methylation of the IL10 gene with increased recruitment of Stat family transcription factors. Stat3 and Stat5 recruitment to the IL10 promoter and an intronic enhancer regulate gene expression. Both Stat3 and Stat5 mediate trans-activation and epigenetic remodeling of IL10 through their interaction with the histone acetyltransferase p300. In T cells from SLE patients, activation of Stat3 is increased, resulting in enhanced recruitment to regulatory regions and competitive replacement of Stat5, subsequently promoting IL-10 expression. A complete understanding of the molecular events governing cytokine expression will provide new treatment options in autoimmune disorders, including SLE. The observation that altered activation of Stat3 influences IL-10 expression in T cells from SLE patients offers molecular targets in the search for novel target-directed treatment options. PMID:25187566

  18. Glycyrrhizic acid inhibits leukemia cell growth and migration via blocking AKT/mTOR/STAT3 signaling

    PubMed Central

    He, Si-Qi; Gao, Meng; Fu, Yun-Feng; Zhang, Ya-Nan

    2015-01-01

    Glycyrrhizic acid (GA) is the bioactive compound of licorice and has been used as an herbal medicine because of its anti-viral, anti-cancer, and anti-inflammatory properties. This study was designed to investigate the effects of GA on leukemia cells growth, migration, and the mechanisms underlying the anti-cancer activities of GA. MTT test was used to detect the effect of GA on TF-1 leukemia cell growth. Wound closure assay and Transwell were adopted to assess the effect of GA on TF-1 migration and invasion. Migration and invasion related proteins including AKT and mTOR were detected by western blot assay. We further used western blot and immunofluorescence assay to evaluate the effect of GA on STAT3 phosphorylation in vitro. We also evaluated the anti-tumor effect of GA in TF-1 tumor bearing BALB/c mice model. The present study showed GA significant inhibit of TF-1 proliferation in a dose and time-dependent manner. GA could remarkably inhibit TF-1 cell migration and invasion; meanwhile effectively suppress AKT, mTOR, and STAT3 phosphorylation in TF-1 cells. GA in 100 mg/kg/ could inhibit the tumor growth in vivo and down-regulated AKT, mTOR, and STAT3 phosphorylation in TF-1 tumor tissues. Our findings suggest that GA is a promising therapeutic agent for leukemia that targets the AKT/mTOR/STAT3 pathway. PMID:26191214

  19. Artocarpus altilis (Parkinson) Fosberg Extracts and Geranyl Dihydrochalcone Inhibit STAT3 Activity in Prostate Cancer DU145 Cells.

    PubMed

    Jeon, Yoon Jung; Jung, Seung-Nam; Chang, Hyeyoun; Yun, Jieun; Lee, Chang Woo; Lee, Joonku; Choi, Sangho; Nash, Oyekanmi; Han, Dong Cho; Kwon, Byoung-Mog

    2015-05-01

    Artocarpus altilis (Parkinson) Fosberg has traditionally been used in Indonesia for the treatment of liver cirrhosis, hypertension, and diabetes. In many other countries, it is used for the treatment of malaria, yellow fever, and dengue fever. It has been reported that A. altilis extracts have antiatherosclerotic and cytoprotective effects, but its molecular targets in tumor cells are not yet fully understood. The A. altilis extracts and the partially purified fraction have been shown to inhibit STAT3 activity and the phosphorylation of STAT3 in a dose-dependent manner. To identify the active components, a bioassay-guided isolation of the partially purified fraction resulted in the identification of a geranyl dihydrochalcone, CG901. Its chemical structure was established on the basis of spectroscopic evidence and comparison with published data. The partially purified fraction and the isolated a geranyl dihydrochalcone, CG901, down-regulated the expression of STAT3 target genes, induced apoptosis in DU145 prostate cancer cells via caspase-3 and PARP degradation, and inhibited tumor growth in human prostate tumor (DU145) xenograft initiation model. These results suggest that A. altilis could be a good natural source and that the isolated compound will be a potential lead molecule for developing novel therapeutics against STAT3-related diseases, including cancer and inflammation. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25682949

  20. STAT3: A Novel Molecular Mediator of Resistance to Chemoradiotherapy.

    PubMed

    Spitzner, Melanie; Ebner, Reinhard; Wolff, Hendrik A; Ghadimi, B Michael; Wienands, Jürgen; Grade, Marian

    2014-01-01

    Chemoradiotherapy (CRT) represents a standard treatment for many human cancers, frequently combined with radical surgical resection. However, a considerable percentage of primary cancers are at least partially resistant to CRT, which represents a substantial clinical problem, because it exposes cancer patients to the potential side effects of both irradiation and chemotherapy. It is therefore exceedingly important to determine the molecular characteristics underlying CRT-resistance and to identify novel molecular targets that can be manipulated to re-sensitize resistant tumors to CRT. In this review, we highlight much of the recent evidence suggesting that the signal transducer and activator of transcription 3 (STAT3) plays a prominent role in mediating CRT-resistance, and we outline why inhibition of STAT3 holds great promise for future multimodal treatment concepts in oncology. PMID:25268165

  1. STAT3: A Novel Molecular Mediator of Resistance to Chemoradiotherapy

    PubMed Central

    Spitzner, Melanie; Ebner, Reinhard; Wolff, Hendrik A.; Ghadimi, B. Michael; Wienands, Jürgen; Grade, Marian

    2014-01-01

    Chemoradiotherapy (CRT) represents a standard treatment for many human cancers, frequently combined with radical surgical resection. However, a considerable percentage of primary cancers are at least partially resistant to CRT, which represents a substantial clinical problem, because it exposes cancer patients to the potential side effects of both irradiation and chemotherapy. It is therefore exceedingly important to determine the molecular characteristics underlying CRT-resistance and to identify novel molecular targets that can be manipulated to re-sensitize resistant tumors to CRT. In this review, we highlight much of the recent evidence suggesting that the signal transducer and activator of transcription 3 (STAT3) plays a prominent role in mediating CRT-resistance, and we outline why inhibition of STAT3 holds great promise for future multimodal treatment concepts in oncology. PMID:25268165

  2. STAT3 regulated ARF expression suppresses prostate cancer metastasis

    E-print Network

    Pencik, Jan; Schlederer, Michaela; Gruber, Wolfgang; Unger, Christine; Walker, Steven M.; Chalaris, Athena; Marié, Isabelle J.; Hassler, Melanie R.; Javaheri, Tahereh; Aksoy, Osman; Blayney, Jaine K.; Prutsch, Nicole; Skucha, Anna; Herac, Merima; Krämer, Oliver H.; Mazal, Peter; Grebien, Florian; Egger, Gerda; Poli, Valeria; Mikulits, Wolfgang; Eferl, Robert; Esterbauer, Harald; Kennedy, Richard; Fend, Falko; Scharpf, Marcus; Braun, Martin; Perner, Sven; Levy, David E.; Malcolm, Tim; Turner, Suzanne D.; Haitel, Andrea; Susani, Martin; Moazzami, Ali; Rose-John, Stefan; Aberger, Fritz; Merkel, Olaf; Moriggl, Richard; Culig, Zoran; Dolznig, Helmut; Kenner, Lukas

    2015-01-01

    for prostate cancer prognosis, diagnosis, and follow-up. Biomed Res Int 2014, 890697 (2014). 4. Ost, P. et al. Prognostic factors influencing prostate cancer-specific survival in non-castrate patients with metastatic prostate cancer. Prostate 74, 297... ), an anti-IL- 6 monoclonal antibody, in combination with mitoxantrone/prednisone versus mitoxantrone/prednisone alone in metastatic castration-resistant prostate cancer. Eur J Cancer 48, 85-93 (2012). 10. Song, M.S., Salmena, L. & Pandolfi, P...

  3. Stat3 orchestrates interaction between endothelial and tumor cells and inhibition of Stat3 suppresses brain metastasis of breast cancer cells

    PubMed Central

    Chou, Ping-Chieh; Zhou, Aidong; Yang, Phillip; Conrad, Charles A.; Aldape, Kenneth D.; Priebe, Waldemar; Patterson, Cam; Sawaya, Raymond; Xie, Keping; Huang, Suyun

    2015-01-01

    Brain metastasis is a major cause of morbidity and mortality in patients with breast cancer. Our previous studies indicated that Stat3 plays an important role in brain metastasis. Here, we present evidence that Stat3 functions at the level of the microenvironment of brain metastases. Stat3 controlled constitutive and inducible VEGFR2 expression in tumor-associated brain endothelial cells. Furthermore, inhibition of Stat3 by WP1066 decreased the incidence of brain metastases and increased survival in a preclinical model of breast cancer brain metastasis. WP1066 inhibited Stat3 activation in tumor-associated endothelial cells, reducing their infiltration and angiogenesis. WP1066 also inhibited breast cancer cell invasion. Our results indicate that WP1066 can inhibit tumor angiogenesis and brain metastasis mediated by Stat3 in endothelial and tumor cells. PMID:25881542

  4. Enhancement of Hypothalamic STAT3 Acetylation by Nuclear Receptor Nur77 Dictates Leptin Sensitivity.

    PubMed

    Chen, Yan; Wu, Rong; Chen, Hang-Zi; Xiao, Qian; Wang, Wei-Jia; He, Jian-Ping; Li, Xiao-Xue; Yu, Xian-Wen; Li, Li; Wang, Peng; Wan, Xi-Chen; Tian, Xin-Hua; Li, Shu-Jing; Yu, Xiang; Wu, Qiao

    2015-06-01

    Leptin, an anorexigenic hormone in the hypothalamus, suppresses food intake and increases energy expenditure. Failure to respond to leptin will lead to obesity. Here, we discovered that nuclear receptor Nur77 expression is lower in the hypothalamus of obese mice compared with normal mice. Injection of leptin results in significant reduction in body weight in wild-type mice but not in Nur77 knockout (KO) littermates or mice with specific Nur77 knockdown in the hypothalamus. Hypothalamic Nur77 not only participates in leptin central control of food intake but also expands leptin's reach to liver and adipose tissues to regulate lipid metabolism. Nur77 facilitates signal transducer and activator of transcription 3 (STAT3) acetylation by recruiting acetylase p300 and disassociating deacetylase histone deacetylase 1 (HDAC1) to enhance the transcriptional activity of STAT3 and consequently modulates the expression of downstream gene Pomc in the hypothalamus. Nur77 deficiency compromises response to leptin in mice fed a high-fat diet. Severe leptin resistance in Nur77 KO mice with increased appetite, lower energy expenditure, and hyperleptinemia contributes to aging-induced obesity. Our study opens a new avenue for regulating metabolism with Nur77 as the positive modulator in the leptin-driven antiobesity in the hypothalamus. PMID:25576055

  5. Farnesol inhibits tumor growth and enhances the anticancer effects of bortezomib in multiple myeloma xenograft mouse model through the modulation of STAT3 signaling pathway.

    PubMed

    Lee, Jong Hyun; Kim, Chulwon; Kim, Sung-Hoon; Sethi, Gautam; Ahn, Kwang Seok

    2015-05-01

    Aberrant activation of signal transducer and activator of transcription 3 (STAT3) is frequently observed in multiple myeloma (MM) cancer and can upregulate the expression of several genes involved in proliferation, survival, metastasis, and angiogenesis. The effect of farnesol (FOH) on STAT3 activation, associated protein kinases, its regulated gene products, cellular proliferation, and apoptosis was examined. The in vivo effect of FOH on the growth of human MM xenograft tumors alone and in combination with bortezomib (Bor) in athymic nu/nu female mice was also investigated. We found that FOH suppressed both constitutive and inducible STAT3 activation at Tyr705 in MM cells. The suppression of STAT3 was mediated through the inhibition of activation of upstream JAK1, JAK2, and c-Src kinases. Also, treatment with the protein tyrosine phosphatase (PTP) inhibitor, pervanadate treatment reversed the FOH-induced down-regulation of STAT3, possibly indicating the involvement of a PTP. Indeed, we found that FOH treatment induces the increased expression of SHP-2 protein and knockdown of the SHP-2 gene by small interfering RNA suppressed the ability of FOH to inhibit STAT3 activation. FOH inhibited proliferation and significantly potentiated the apoptotic effects of bortezomib (Bor) in U266 cells. When administered intraperitoneally, FOH enhanced Bor-induced growth suppression of human MM xenograft tumors in athymic nu/nu female mice. Our results suggest that FOH is a novel blocker of STAT3 signaling pathway and exerts both anti-proliferative and apoptotic activities in MM in vitro and in vivo. PMID:25697480

  6. Chrysin overcomes TRAIL resistance of cancer cells through Mcl-1 downregulation by inhibiting STAT3 phosphorylation.

    PubMed

    Lirdprapamongkol, Kriengsak; Sakurai, Hiroaki; Abdelhamed, Sherif; Yokoyama, Satoru; Athikomkulchai, Sirivan; Viriyaroj, Amornrat; Awale, Suresh; Ruchirawat, Somsak; Svasti, Jisnuson; Saiki, Ikuo

    2013-07-01

    Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) selectively kills various types of cancer cells without harming normal cells, but TRAIL resistance has been frequently observed in cancer cells. Propolis (bee glue) is a material collected from various plants by honeybees and is a rich source of bioactive compounds, including the natural flavonoid chrysin, which possesses multiple anticancer effects. We investigated the mechanism underlying the TRAIL sensitization effect of chrysin, which is a major constituent of Thai propolis, in human lung and cervical cancer cell lines. Propolis extract and chrysin sensitizes A549 and HeLa human cancer cell lines to TRAIL-induced apoptosis. The TRAIL sensitization effect of chrysin is not mediated by inhibition of TRAIL-induced NF-?B activation or by glutathione depletion. Immunoblot analysis using a panel of anti-apoptotic proteins revealed that chrysin selectively decreases the levels of Mcl-1 protein, by downregulating Mcl-1 gene expression as determined by qRT-PCR. The contribution of Mcl-1 in TRAIL resistance was confirmed by si-Mcl-1 knockdown. Among signaling pathways that regulate Mcl-1 gene expression, only constitutive STAT3 phosphorylation was suppressed by chrysin. The proposed action of chrysin in TRAIL sensitization by inhibiting STAT3 and downregulating Mcl-1 was supported by using a STAT3?specific inhibitor, cucurbitacin-I, which decreased Mcl-1 levels and enhanced TRAIL-induced cell death, similar to that observed with chrysin treatment. In conclusion, we show the potential of chrysin in overcoming TRAIL resistance of cancer cells and elucidate its mechanism of action. PMID:23636231

  7. Inhibition of a novel specific neuroglial integrin signaling pathway increases STAT3-mediated CNTF expression

    PubMed Central

    2013-01-01

    Background Ciliary neurotrophic factor (CNTF) expression is repressed in astrocytes by neuronal contact in the CNS and is rapidly induced by injury. Here, we defined an inhibitory integrin signaling pathway. Results The integrin substrates laminin, fibronectin and vitronectin, but not collagen, thrombospondin or fibrinogen, reduced CNTF expression in C6 astroglioma cells. Antibodies against ?v and ?5, but not ?6 or ?1, integrin induced CNTF. Together, the ligand and antibody specificity suggests that CNTF is repressed by ?v?5 integrin. Antibodies against Thy1, an abundant neuronal surface protein whose function is unclear, induced CNTF in neuron-astrocyte co-cultures indicating that it is a neuroglial CNTF repressor. Inhibition of the integrin signaling molecule Focal Adhesion Kinase (FAK) or the downstream c-Jun N-terminal kinase (JNK), but not extracellular regulated kinase (ERK) or p38 MAPK, greatly induced CNTF mRNA and protein expression within 4 hours. This selective inhibitory pathway phosphorylated STAT3 on its inhibitory ser-727 residue interfering with activity of the pro-transcription Tyr-705 residue. STAT3 can activate CNTF transcription because it bound to its promoter and FAK antagonist-induced CNTF was reduced by blocking STAT3. Microinjection of FAK inhibitor directly into the brain or spinal cord in adult mice rapidly induced CNTF mRNA and protein expression. Importantly, systemic treatment with FAK inhibitors over 3 days induced CNTF in the subventricular zone and increased neurogenesis. Conclusions Neuron-astroglia contact mediated by integrins serves as a sensor to enable rapid neurotrophic responses and provides a new pharmacological avenue to exploit the neuroprotective properties of endogenous CNTF. PMID:23693126

  8. Expression of p53\\/hgf\\/c-met\\/STAT3 signal in fetuses with neural tube defects

    Microsoft Academic Search

    Maria Trovato; Maria D’Armiento; Luca Lavra; Alessandra Ulivieri; Roberto Dominici; Enrica Vitarelli; Maddalena Grosso; Raffaella Vecchione; Gaetano Barresi; Salvatore Sciacchitano

    2007-01-01

    Neural tube defects (NTD) are morphogenetic alterations due to a defective closure of neural tube. Hepatocyte growth factor\\u000a (HGF)\\/c-met system plays a role in morphogenesis of nervous system, lung, and kidney. HGF\\/c-met morphogenetic effects are\\u000a mediated by signal transducers and activators of transcription (STAT)3 and both HGF and c-met genes are regulated from p53.\\u000a The aim of our study was

  9. Loss of STAT3 in Lymphoma Relaxes NK Cell-Mediated Tumor Surveillance

    PubMed Central

    Putz, Eva Maria; Hoelzl, Maria Agnes; Baeck, Julia; Bago-Horvath, Zsuzsanna; Schuster, Christian; Reichholf, Brian; Kern, Daniela; Aberger, Fritz; Sexl, Veronika; Hoelbl-Kovacic, Andrea

    2014-01-01

    The transcription factors and proto-oncogenes STAT3 and STAT5 are highly activated in hematological malignancies and represent promising therapeutic targets. Whereas the importance of STAT5 as tumor promoter is beyond doubt, the role of STAT3 in hematological cancers is less well understood. Both, enforced as well as attenuated expression of STAT3 were reported in hematopoietic malignancies. Recent evidence implicates STAT3 as key player for tumor immune surveillance as it both mediates the production of and response to inflammatory cytokines. Here we investigated the effects of STAT3 deletion in a BCR/ABL-induced lymphoma model, which is tightly controlled by natural killer (NK) cells in vivo. Upon STAT3 deletion tumor growth is significantly enhanced when compared to STAT3-expressing controls. The increased tumor size upon loss of STAT3 was accompanied by reduced NK cell infiltration and decreased levels of the cytokine IFN-? and the chemokine RANTES. Upon transplantation into NK cell-deficient mice differences in lymphoma size were abolished indicating that STAT3 expression in the tumor cells controls NK cell-dependent tumor surveillance. Our findings indicate that STAT3 inhibition in lymphoma patients will impair NK cell-mediated tumor surveillance, which needs to be taken into account when testing STAT3 inhibitors in preclinical or clinical trials. PMID:24473086

  10. Unphosphorylated STAT3 modulates alpha7 nicotinic receptor signaling and cytokine production in sepsis

    PubMed Central

    Peña, Geber; Cai, Bolin; Liu, Jun; van der Zanden, Esmerij P.; Deitch, Edwin A.; de Jonge, Wouter J.; Ulloa, Luis

    2011-01-01

    The role of STAT3 in infectious diseases remains undetermined, in part because unphosphorylated STAT3 has been considered an inactive protein. Here, we report that unphosphorylated STAT3 contributes to cholinergic anti-inflammation, prevents systemic inflammation, and improves survival in sepsis. Bacterial endotoxin induced STAT3 tyrosine phosphorylation in macrophages. Both alpha7 nicotinic receptor (alpha7nAChR) activation and inhibition of JAK2 blunt STAT3 phosphorylation. Inhibition of STAT3 phosphorylation mimicked the alpha7nAChR signaling, inhibiting NF-?B and cytokine production in macrophages. Transfection of macrophages with the dominant-negative mutant STAT3F, to prevent its tyrosine phosphorylation, reduced TNF production but did not prevent the alpha7nAChR signaling. However, inhibition of STAT3 protein expression enhanced cytokine production and abrogated alpha7nAChR signaling. Alpha7nAChR controls TNF production in macrophages through a mechanism that requires STAT3 protein expression, but not its tyrosine phosphorylation. In vivo, inhibition of STAT3 tyrosine phosphorylation by stattic prevented systemic inflammation and improved survival in experimental sepsis. Stattic also prevented the production of late mediators of sepsis and improved survival in established sepsis. These results reveal the immunological implications of tyrosine-unphosphorylated STAT3 in infectious diseases. PMID:20706987

  11. The Role of STAT3 in Non-Small Cell Lung Cancer

    PubMed Central

    Harada, Daijiro; Takigawa, Nagio; Kiura, Katsuyuki

    2014-01-01

    Persistent phosphorylation of signal transducer and activator of transcription 3 (STAT3) has been demonstrated in 22%~65% of non-small cell lung cancers (NSCLC). STAT3 activation is mediated by receptor tyrosine kinases, such as epidermal growth factor receptor (EGFR) and MET, cytokine receptors, such as IL-6, and non-receptor kinases, such as Src. Overexpression of total or phosphorylated STAT3 in resected NSCLC leads to poor prognosis. In a preclinical study, overexpression of STAT3 was correlated with chemoresistance and radioresistance in NSCLC cells. Here, we review the role of STAT3 and the mechanisms of treatment resistance in malignant diseases, especially NSCLC. As STAT3 is a critical mediator of the oncogenic effects of EGFR mutations, we discuss STAT3 pathways in EGFR-mutated NSCLC, referring to mechanisms of EGFR tyrosine kinase inhibitor resistance. PMID:24675568

  12. STAT3 Oligonucleotide Inhibits Tumor Angiogenesis in Preclinical Models of Squamous Cell Carcinoma

    PubMed Central

    Klein, Jonah D.; Sano, Daisuke; Sen, Malabika; Myers, Jeffrey N.; Grandis, Jennifer R.; Kim, Seungwon

    2014-01-01

    Purpose Signal transducer and activator of transcription 3 (STAT3) has shown to play a critical role in head and neck squamous cell carcinoma (HNSCC) and we have recently completed clinical trials of STAT3 decoy oligonucleotide in patients with recurrent or metastatic HNSCC. However, there is limited understanding of the role of STAT3 in modulating other aspects of tumorigenesis such as angiogenesis. In this study, we aimed to examine the effects of STAT3 decoy oligonucleotide on tumor angiogenesis. Experimental Design A STAT3 decoy oligonucleotide and small interfering RNA (siRNA) were used to inhibit STAT3 in endothelial cells in vitro and in vivo. The biochemical effects of STAT3 inhibition were examined in conjunction with the consequences on proliferation, migration, apoptotic staining, and tubule formation. Additionally, we assessed the effects of STAT3 inhibition on tumor angiogenesis using murine xenograft models. Results STAT3 decoy oligonucleotide decreased proliferation, induces apoptosis, decreased migration, and decreased tubule formation of endothelial cells in vitro. The STAT3 decoy oligonucleotide also inhibited tumor angiogenesis in murine tumor xenografts. Lastly, our data suggest that the antiangiogenic effects of STAT3 decoy oligonucleotide were mediatedthrough the inhibition of both STAT3 and STAT1. Conclusions The STAT3 decoy oligonucleotidewas found to be an effective antiangiogenic agent, which is likely to contribute to the overall antitumor effects of this agent in solid tumors.Taken together with the previously demonstrated antitumor activity of this agent, STAT3 decoy oligonucleotide represents a promising single agent approach to targeting both the tumor and vascular compartments in various malignancies. PMID:24404126

  13. REG3A accelerates pancreatic cancer cell growth under IL-6-associated inflammatory condition: Involvement of a REG3A-JAK2/STAT3 positive feedback loop.

    PubMed

    Liu, Xiulan; Wang, Jun; Wang, Hongjie; Yin, Guoxiao; Liu, Yang; Lei, Xiang; Xiang, Ming

    2015-06-28

    Regenerating gene protein (REG) 3A is a 19 kD secretory pancreas protein with pro-growth function. Previously we demonstrated that overexpression of REG3A, acting as a key molecule for up-regulation of the JAK2/STAT3 pathway, contributed to inflammation-related pancreatic cancer (PaC) development. However the exact network associated with REG3A signaling still remains unclear. Here we determined that exposure of human PaC cells to cytokine IL-6 activated the oncogenic JAK2/STAT3 pathway, which directly upregulated REG3A expression, accelerated cell cycle progression by promoting CyclinD1 expression, and enhancing the expression of the anti-apoptosis Bcl family. Importantly, the activation of REG3A would instead enhance the JAK2/STAT3 pathway to constitute a REG3A-JAK2/STAT3 positive feedback loop, which leads to the amplification of the oncogenic effects of IL-6/JAK2/STAT3, a classic pathway linking to inflammation-related tumorigenesis, ultimately resulting in PaC cell over-proliferation and tumor formation both in vitro and in vivo. Moreover, EGFR was found to mediate the REG3A signal for PaC cell growth and JAK2/STAT3 activation, thus functioning as a REG3A receptor. Collectively, our results provide the first evidence for the presence of the synergistic effect of REG3A and IL-6 on PaC development via a REG3A-JAK2/STAT3 positive feedback loop. PMID:25779676

  14. MicroRNA-520a-5p displays a therapeutic effect upon chronic myelogenous leukemia cells by targeting STAT3 and enhances the anticarcinogenic role of capsaicin.

    PubMed

    Kaymaz, Burçin Tezcanl?; Cetinta?, Vildan Bozok; Aktan, Ca?da?; Kosova, Buket

    2014-09-01

    Aberrant expression profiles of microRNAs (miRNAs) have been previously demonstrated for having essential roles in a wide range of cancer types including leukemia. Antiproliferative or proapoptotic effects of capsaicin have been reported in several cancers. We aimed to study miRNAs involved in the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway in chronic myeloid leukemia cell model and the effects of the capsaicin treatment on cell proliferation and miRNA regulation. miR-520a-5p expression was extremely downregulated in capsaicin-treated cells. Repressing the level of miR-520a-5p by transient transfection with specific miRNA inhibitor oligonucleotides resulted in induced inhibition of proliferation in leukemic cells. According to bioinformatics analysis, STAT3 messenger RNA was predicted as a putative miR-520a-5p target; which was confirmed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and Western blot analysis. Cell proliferation inhibition was enhanced upon knockdown of STAT3 by RNA interference applications, but when miR-520a-5p inhibitor was additionally transfected onto STAT3 silenced cells, cell viability was dramatically decreased in leukemia cells. Finally, we observed the effects of capsaicin following miR-520a-5p inhibitor transfection upon cell proliferation, apoptosis, and STAT3 expression levels. We determined that, downregulation of miR-520a-5p affected the proliferation inhibition enhanced by capsaicin and reduced STAT3 mRNA and protein expression levels and increased apoptotic cell number. In summary, miR-520a-5p displays a therapeutic effect by targeting STAT3 and impacting the anticancer effects of capsaicin; whereas capsaicin, potentially through the miR-520a-5p/STAT3 interaction, induces apoptosis and inhibits K562 leukemic cell proliferation with need of further investigation. PMID:24870597

  15. Induction of STAT3-related genes in fast degenerating cone photoreceptors of cpfl1 mice.

    PubMed

    Schaeferhoff, K; Michalakis, S; Tanimoto, N; Fischer, M D; Becirovic, E; Beck, S C; Huber, G; Rieger, N; Riess, O; Wissinger, B; Biel, M; Seeliger, M W; Bonin, M

    2010-09-01

    Cone dystrophies are genetic diseases characterized by loss of cone photoreceptor function and severe impairment of daylight vision. Loss of function is accompanied by a progressive degeneration of cones limiting potential therapeutic interventions. In this study we combined microarray-based gene-expression analysis with electroretinography and immunohistochemistry to characterize the pathological processes in the cone photoreceptor function loss 1 (cpfl1) mouse model. The cpfl1-mouse is a naturally arising mouse mutant with a loss-of-function mutation in the cone-specific Pde6c gene. Cpfl1-mice displayed normal rod-specific light responses while cone-specific responses were strongly diminished. Despite the lack of a general retinal degeneration, the cone-specific functional defect resulted in a marked activation of GFAP, a hallmark of Müller-cell gliosis. Microarray-based network-analysis confirmed activation of Müller-glia-specific transcripts. Unexpectedly, we found up-regulation of the cytokine LIF and the anti-apoptotic transcription factor STAT3 in cpfl1 cone photoreceptors. We postulate that STAT3-related pathways are induced in cpfl1 cone photoreceptors to counteract degeneration. PMID:20467778

  16. Early methyl donor deficiency may induce persistent brain defects by reducing Stat3 signaling targeted by miR-124

    PubMed Central

    Kerek, R; Geoffroy, A; Bison, A; Martin, N; Akchiche, N; Pourié, G; Helle, D; Guéant, J-L; Bossenmeyer-Pourié, C; Daval, J-L

    2013-01-01

    The methyl donors folate (vitamin B9) and vitamin B12 are centrepieces of the one-carbon metabolism that has a key role in transmethylation reactions, and thus in epigenetic and epigenomic regulations. Low dietary intakes of folate and vitamin B12 are frequent, especially in pregnant women and in the elderly, and deficiency constitutes a risk factor for various diseases, including neurological and developmental disorders. In this respect, both vitamins are essential for normal brain development, and have a role in neuroplasticity and in the maintenance of neuronal integrity. The consequences of a methyl donor deficiency (MDD) were studied both in vivo in rats exposed in utero, and in vitro in hippocampal progenitors (H19-7 cell line). Deficiency was associated with growth retardation at embryonic day 20 (E20) and postnatally with long-term brain defects in selective areas. mRNA and protein levels of the transcription factor Stat3 were found to be decreased in the brains of deprived fetuses and in differentiating progenitors (62 and 48% for total Stat3 protein, respectively), along with a strong reduction in its phosphorylation at both Tyr705 and Ser727 residues. Vitamin shortage also affected upstream kinases of Stat3 signaling pathway (phospho-Erk1/2, phospho-Src, phospho-JNK, and phospho-p38) as well as downstream target gene products (Bcl-2 and Bcl-xL), thus promoting apoptosis. Conversely, the expression of the Stat3 regulator miR-124 was upregulated in deficiency conditions (?65%), and its silencing by using siRNA partly restored Stat3 signaling in hippocampal neurons by increasing specifically the phosphorylation of Erk1/2 and Src kinases. Furthermore, miR-124 siRNA improved the phenotype of deprived cells, with enhanced neurite outgrowth. Taken together, our data suggest that downregulation of Stat3 signaling by miR-124 would be a key factor in the deleterious effects of MDD on brain development. PMID:23928694

  17. The IL-6 family of cytokines modulates STAT3 activation by desumoylation of PML through SENP1 induction

    SciTech Connect

    Ohbayashi, Norihiko; Kawakami, Shiho; Muromoto, Ryuta; Togi, Sumihito; Ikeda, Osamu; Kamitani, Shinya; Sekine, Yuichi [Department of Immunology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-Ku Kita 12 Nishi 6, Sapporo 060-0812 (Japan); Honjoh, Tsutomu [Morinaga Institute of Biological Sciences, Inc., 2-1-16, Sachiura, Kanazawa-ku, Yokohama 236-0003 (Japan); Matsuda, Tadashi [Department of Immunology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-Ku Kita 12 Nishi 6, Sapporo 060-0812 (Japan)], E-mail: tmatsuda@pharm.hokudai.ac.jp

    2008-07-11

    Post-translational modification by small ubiquitin-like modifier (SUMO) plays an important role in the regulation of different signaling pathways and is involved in the formation of promyelocytic leukemia (PML) protein nuclear bodies following sumoylation of PML. In the present study, we found that IL-6 induces desumoylation of PML and dissociation between PML and SUMO1 in hepatoma cells. We also found that IL-6 induces mRNA expression of SENP1, a member of the SUMO-specific protease family. Furthermore, wild-type SENP1 but not an inactive SENP1 mutant restored the PML-mediated suppression of STAT3 activation. These results indicate that the IL-6 family of cytokines modulates STAT3 activation by desumoylation and inactivation PML through SENP1 induction.

  18. AAG8 promotes carcinogenesis by activating STAT3.

    PubMed

    Sun, Bing; Kawahara, Masahiro; Ehata, Shogo; Nagamune, Teruyuki

    2014-09-01

    Dysregulation of signalling pathways by changes of gene expression contributes to hallmarks of cancer. The ubiquitously expressed chaperone protein AAG8 (aging-associated gene 8 protein, encoded by the SIGMAR1 gene) is often found to be overexpressed in various cancers. AAG8 is involved in ER (endoplasmic reticulum)-associated degradation and has been intensively elaborated in neuroscience. However, its rationale in carcinogenesis has rarely been noticed. In this study, we explored the intrinsic oncogenetic roles of AAG8 in cancer cells and found that AAG8 promoted carcinogenesis both in vitro and in vivo. We further characterized AAG8, for the first time to our knowledge, as a STAT3 activator and elucidated that it alternatively activated STAT3 in addition to IL6/JAK pathway. Based on these findings and a drug screening study, we demonstrated that combined inhibition of AAG8 and IL6/JAK signalling synergistically limits cancer cell growth. Taken together, our findings shed light on the fundamental evidences for identification of AAG8 as an oncoprotein and potential target for cancer prevention, as well as highlight the importance of ER proteins in contributing to JAK/STAT signaling and carcinogenesis. PMID:24726897

  19. STAT3- and DNA methyltransferase 1-mediated epigenetic silencing of SHP-1 tyrosine phosphatase tumor suppressor gene in malignant T lymphocytes

    PubMed Central

    Zhang, Qian; Wang, Hong Y.; Marzec, Michal; Raghunath, Puthiyaveettil N.; Nagasawa, Tomohiko; Wasik, Mariusz A.

    2005-01-01

    Expression of SHP-1 phosphatase, a key negative regulator of cell signaling, is lost in T cell lymphomas and other malignancies due to DNA methylation of the SHP-1 promoter by a currently undefined mechanism. We demonstrate that malignant T cells express DNA methyltransferase (DNMT) 1 and that constantly activated signal transducer and activator of transcription (STAT) 3 is capable of binding in vitro to DNA oligonucleotides corresponding to four STAT3 SIE/GAS binding sites identified in the SHP-1 promoter. STAT3, DNMT1, and histone deacetylase 1 form complexes and bind to the SHP-1 promoter in vivo. Treatment with pharmacologic grade DNMT1 anti-sense oligonucleotides and STAT3 small-interfering RNA induces in the malignant T cells DNA demethylation and expression of SHP-1 gene. These data indicate that STAT3 may, in part, transform cells by inducing epigenetic silencing of SHP-1 in cooperation with DNMT1 and, apparently, histone deacetylase 1. Reversal of such gene silencing represents an attractive aim for novel anticancer therapies. PMID:15870198

  20. Special suppressive role of miR-29b in HER2-positive breast cancer cells by targeting Stat3

    PubMed Central

    Qin, Ling; Li, Rong; Zhang, Junyi; Li, Aimin; Luo, Rongcheng

    2015-01-01

    Objectives: MiR-29b has been reported to function as a tumor suppressor in a variety of cancers. However, its role in the regulation of breast cancer is controversial. Materials and methods: In this paper, we explored the expression of miR-29b in a cohort of 67 pairs of formalin-fixed paraffin-embedded specimens with detailed pathological and clinical characteristics, and further analyzed the effects of miR-29b on the malignant phenotype of HER-2-positive breast cancer cells and the relevant mechanisms involved. Results: We found that the miR-29b expression is negatively associated with HER-2 expression in breast cancer tissues. Moreover, overexpression of miR-29b induced a complex phenotype in HER-2-positive breast cancer cells, namely an inhibition of cell proliferation, block of G1/S phase transition, induction of cell apoptosis, suppression of cell invasion in vitro, as well as inhibition on tumor growth in vivo, indicating that miR-29b functions as a tumor suppressor in HER2-positive breast cancer cells. Further bioinformatic prediction suggested that oncogene Stat3, which is an up-stream regulator of HER-2, was a target gene of miR-29b in breast cancer cells. We have shown that knocking down of Stat3 attenuated the malignant phenotype of breast cancer cells similar to overexpression of miR-29b, while restore expression of Stat3 in HER-2-positive breast cancer cells partially abolished the suppressive effects of miR-29b. Conclusion: Collectively, our data suggest that miR-29b could reverse the malignant phenotype of HER-2-positvie breast cancer through, at least partially, targeting Stat3 signaling pathway.

  1. Overexpression of P-glycoprotein, STAT3, phospho-STAT3 and KIT in spontaneous canine cutaneous mast cell tumours before and after prednisolone treatment.

    PubMed

    Teng, Shr-Ping; Hsu, Wei-Li; Chiu, Cheng-Yang; Wong, Min-Liang; Chang, Shih-Chieh

    2012-08-01

    Prednisolone is a glucocorticoid (GC) commonly used in the treatment of canine mast cell tumours (MCTs); however, resistance to GCs develops in many MCTs following repeated treatment. P-glycoprotein (P-gp), signal transducer and activator of transcription 3 (STAT3) and KIT (CD117) are involved in GC resistance. The aim of this study was to evaluate the response to prednisolone treatment in canine cutaneous MCTs and to investigate the levels of P-gp, STAT3, phospho-STAT3 (pSTAT3) and KIT proteins in MCTs with or without prednisolone treatment. Immunohistochemistry was performed on tumour samples from 41 dogs with cutaneous MCTs. The overall objective response rate (including complete and partial responses) was 51.8% for dogs treated with prednisolone; poorly differentiated or higher stage MCTs had a lower response rate. The median time-span of tumours to reach maximal tumour regression was 14 d (range 3-77 d); 22 (81.5%) reached maximal regression at 21 d. The majority of MCTs overexpressed both P-gp and STAT3 before and after prednisolone treatment. Reduced expression of pSTAT3 and alterations in the KIT expression pattern were observed in MCTs post-treatment. Prednisolone treatment that caused a marked reduction in tumour volume was correlated with reduced pSTAT3 expression. A cytoplasmic KIT staining pattern was correlated with a lower tumour response rate to prednisolone treatment. PMID:22398132

  2. Rapid communication Genetic depletion of cardiac myocyte STAT3 abolishes classical preconditioning

    Microsoft Academic Search

    Robert M. Smith; Naushaad Suleman; Lydia Lacerda; Lionel H. Opie; Shizuo Akira; Kenneth R. Chien; Michael N. Sack

    Objective: To evaluate the functional requirement of signal transducer and activator of transcription-3 (STAT-3) in cardiac myocyte tolerance to ischemia (I) and in classical preconditioning. Methods: Cardiac myocyte STAT-3 was depleted in mice using Cre-lox p technology. Isolated cardiomyocytes from wild-type (WT) and STAT-3-deficient mice were evaluated for viability following simulated ischemia (SI; 26 h). Cardiomyocytes were then preconditioned by

  3. Cucurbitacin Q: a selective STAT3 activation inhibitor with potent antitumor activity

    Microsoft Academic Search

    Jiazhi Sun; Michelle A Blaskovich; Richard Jove; Sandra K Livingston; Domenico Coppola; Saïd M Sebti

    2005-01-01

    Constitutive activation of the JAK\\/STAT3 pathway is a major contributor to oncogenesis. In the present study, structure–activity relationship (SAR) studies with five cucurbitacin (Cuc) analogs, A, B, E, I, and Q, led to the discovery of Cuc Q, which inhibits the activation of STAT3 but not JAK2; Cuc A which inhibits JAK2 but not STAT3 activation; and Cuc B, E,

  4. Survivin suppression through STAT3/?-catenin is essential for resveratrol-induced melanoma apoptosis.

    PubMed

    Habibie; Yokoyama, Satoru; Abdelhamed, Sherif; Awale, Suresh; Sakurai, Hiroaki; Hayakawa, Yoshihiro; Saiki, Ikuo

    2014-08-01

    Although many chemotherapies have been developed for melanomas, successful therapy would be aided by the identification of intrinsic mechanisms that are crucial for melanoma survival. Here, we used resveratrol, a phytoalexin, as an anti-melanoma reagent. Applying resveratrol to various human and murine melanoma cell lines, we show that survivin is essential for melanoma survival in vitro and in vivo and is targeted by resveratrol. Furthermore, we identify the down regulation of survivin transcription by resveratrol through the suppression of ?-catenin and STAT3. In addition, over expression of survivin protects melanoma cells from resveratrol-induced apoptosis. Collectively, these studies establish that targeting survivin could provide an opportunity to treat melanoma patients. PMID:24946930

  5. Icaritin suppresses multiple myeloma, by inhibiting IL-6/JAK2/STAT3.

    PubMed

    Zhu, Shicong; Wang, Zhihua; Li, Zijian; Peng, Hongling; Luo, Yunya; Deng, Mingyang; Li, Ruijuan; Dai, Chongwen; Xu, Yunxiao; Liu, Sufang; Zhang, Guangsen

    2015-04-30

    Icaritin is an active prenylflavonoid derived from Epimedium genus, a traditional Chinese medicine. Icaritin has a wide range of pharmacological and biological activities, including cardiovascular function improvement, hormone regulation and antitumor activity. Here, we investigated the effect of icaritin on multiple myeloma (MM) in vitro and in vivo. Icaritin inhibited cell growth of MM cell line and primary MM cells. In contrast, icaritin had low or no cytotoxic effect on normal hematopoiesis. We also demonstrated that in MM xenograft mouse models, icaritin suppressed tumor growth and decreased serum IL-6 and IgE levels, but did not show adverse reactions such as body weight loss. The anti-MM activity of icaritin was mainly mediated by inhibiting IL-6/JAK2/STAT3 signaling. We suggest that icaritin can be further tested in clinical trials in MM. PMID:25865044

  6. Oncostatin M Promotes Osteoblastic Differentiation of Human Vascular Smooth Muscle Cells Through JAK3-STAT3 Pathway.

    PubMed

    Kakutani, Yoshinori; Shioi, Atsushi; Shoji, Tetsuo; Okazaki, Hirokazu; Koyama, Hidenori; Emoto, Masanori; Inaba, Masaaki

    2015-07-01

    Vascular calcification is a clinically significant component of atherosclerosis and arises from chronic vascular inflammation. Oncostatin M (OSM) derived from plaque macrophages may contribute to the development of atherosclerotic calcification. Here, we investigated the stimulatory effects of OSM on osteoblastic differentiation of human vascular smooth muscle cells (HVSMC) derived from various arteries including umbilical artery, aorta, and coronary artery and its signaling pathway. Osteoblastic differentiation was induced by exposure of HVSMC to osteogenic differentiation medium (ODM) (10% fetal bovine serum, 0.1??M dexamethasone, 10?mM ?-glycerophosphate and 50??g/ml ascorbic acid 2-phosphate in Dulbecco's modified Eagle's medium [DMEM]). OSM significantly increased alkaline phosphate (ALP) activity and matrix mineralization in HVSMC from all sources. Osteoblast marker genes such as ALP and Runx2 were also up-regulated by OSM in these cells. OSM treatment induced activation of STAT3 in HVSMC from umbilical artery as evidenced by immunoblot. Moreover, not only a JAK3 inhibitor, WHI-P154, but also knockdown of JAK3 by siRNA prevented the OSM-induced ALP activity and matrix mineralization in umbilical artery HVSMC. On the other hand, silencing of STAT3 almost completely suppressed OSM-induced ALP expression and matrix mineralization in HVSMC from all sources. These data suggest that OSM promotes osteoblastic differentiation of vascular smooth muscle cells through JAK3/STAT3 pathway and may contribute to the development of atherosclerotic calcification. J. Cell. Biochem. 116: 1325-1333, 2015. © 2015 Wiley Periodicals, Inc. PMID:25735629

  7. Novel high-throughput screening system for identifying STAT3-SH2 antagonists

    SciTech Connect

    Uehara, Yutaka; Mochizuki, Masato; Matsuno, Kenji [Center for Drug Discovery, Graduate School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526 (Japan); Haino, Takeharu [Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan); Asai, Akira [Center for Drug Discovery, Graduate School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526 (Japan)], E-mail: aasai@u-shizuoka-ken.ac.jp

    2009-03-13

    Constitutive activation of the oncogenic transcription factor STAT3 frequently occurs in various human malignancies. STAT3 activation involves dimerization via intermolecular pTyr-SH2 interaction. Thus, antagonizing this interaction is a feasible approach to inhibit STAT3 activation for cancer therapy. In order to identify selective STAT3 inhibitors, we developed a biochemical HTS system based on AlphaScreen technology, which measures the abilities of test compounds to antagonize pTyr-SH2 interactions. We screened our chemical libraries using this system and identified 5,15-diphenylporphyrin (5,15-DPP) as a selective STAT3-SH2 antagonist. Selective inhibition of STAT3 nuclear translocation and DNA biding activity was observed in cells treated with 5,15-DPP. IL-6-dependent dimerization of STAT3, c-myc promoter binding and c-myc protein expression were all suppressed by 5,15-DPP, whereas no decrement in either expression or phosphorylation level of STAT3 was observed. Thus, the HTS assay system represented herein may be useful for identifying novel STAT3-SH2 antagonists.

  8. Gefitinib resistance resulted from STAT3-mediated Akt activation in lung cancer cells

    PubMed Central

    Wu, Kai; Chang, Qingshan; Lu, Yongju; Qiu, Ping; Chen, Bailing; Thakur, Chitra; Sun, Jiaying; Li, Lingzhi; Kowluru, Anjaneyulu; Chen, Fei

    2013-01-01

    Hyperactivation of Epidermal Growth Factor Receptor (EGFR) tyrosine kinase is prevalent in human lung cancer and its inhibition by the tyrosine kinase inhibitors (TKIs), including gefitinib and erlotinib, initially controls tumor growth. However, most patients ultimately relapse due to the development of drug resistance. In this study, we have discovered a STAT3-dependent Akt activation that impairs the efficacy of gefitinib. Mechanistically, gefitinib increased association of EGFR with STAT3, which de-repressed STAT3 from SOCS3, an upstream suppressor of STAT3. Such a de-repression of STAT3 in turn fostered Akt activation. Genetic or pharmacological inhibition of STAT3 abrogated Akt activation and combined gefitinib with STAT3 inhibition synergistically reduced the growth of the tumor cells. Taken together, this study suggests that activation of STAT3 is an intrinsic mechanism of drug resistance in response to EGFR TKIs. Combinational targeting on both EGFR and STAT3 may enhance the efficacy of gefitinib or other EGFR TKIs in lung cancer. PMID:24280348

  9. Critical role of STAT3 in IL-6-mediated drug resistance in human neuroblastoma.

    PubMed

    Ara, Tasnim; Nakata, Rie; Sheard, Michael A; Shimada, Hiroyuki; Buettner, Ralf; Groshen, Susan G; Ji, Lingyun; Yu, Hua; Jove, Richard; Seeger, Robert C; DeClerck, Yves A

    2013-07-01

    Drug resistance is a major cause of treatment failure in cancer. Here, we have evaluated the role of STAT3 in environment-mediated drug resistance (EMDR) in human neuroblastoma. We determined that STAT3 was not constitutively active in most neuroblastoma cell lines but was rapidly activated upon treatment with interleukin (IL)-6 alone and in combination with the soluble IL-6 receptor (sIL-6R). Treatment of neuroblastoma cells with IL-6 protected them from drug-induced apoptosis in a STAT3-dependent manner because the protective effect of IL-6 was abrogated in the presence of a STAT3 inhibitor and upon STAT3 knockdown. STAT3 was necessary for the upregulation of several survival factors such as survivin (BIRC5) and Bcl-xL (BCL2L1) when cells were exposed to IL-6. Importantly, IL-6-mediated STAT3 activation was enhanced by sIL-6R produced by human monocytes, pointing to an important function of monocytes in promoting IL-6-mediated EMDR. Our data also point to the presence of reciprocal activation of STAT3 between tumor cells and bone marrow stromal cells including not only monocytes but also regulatory T cells (Treg) and nonmyeloid stromal cells. Thus, the data identify an IL-6/sIL-6R/STAT3 interactive pathway between neuroblastoma cells and their microenvironment that contributes to drug resistance. PMID:23633489

  10. Stat3 induces oncogenic Skp2 expression in human cervical carcinoma cells

    SciTech Connect

    Huang, Hanhui [Shanghai Medical College of Fudan University, Shanghai 200032 (China)] [Shanghai Medical College of Fudan University, Shanghai 200032 (China); Zhao, Wenrong [Department of Gynecology, Obstetrics and Gynecology Hospital of Fudan University, Shanghai 200011 (China)] [Department of Gynecology, Obstetrics and Gynecology Hospital of Fudan University, Shanghai 200011 (China); Yang, Dan, E-mail: yangdandr@gmail.com [Department of Gynecology, Shanghai First Maternity and Infant Hospital, Tongji University, Shanghai 200040 (China)] [Department of Gynecology, Shanghai First Maternity and Infant Hospital, Tongji University, Shanghai 200040 (China)

    2012-02-03

    Highlights: Black-Right-Pointing-Pointer Upregulation of Skp2 by IL-6 or Stat3 activation. Black-Right-Pointing-Pointer Stat3 activates Skp2 expression through bound to its promoter region. Black-Right-Pointing-Pointer Stat3 activates Skp2 expression through recruitment of P300. Black-Right-Pointing-Pointer Stat3 activation decreases the P27 stability. -- Abstract: Dysregulated Skp2 function promotes cell proliferation, which is consistent with observations of Skp2 over-expression in many types of human cancers, including cervical carcinoma (CC). However, the molecular mechanisms underlying elevated Skp2 expression have not been fully explored. Interleukin-6 (IL-6) induced Stat3 activation is viewed as crucial for multiple tumor growth and metastasis. Here, we demonstrate that Skp2 is a direct transcriptional target of Stat3 in the human cervical carcinoma cells. Our data show that IL-6 administration or transfection of a constitutively activated Stat3 in HeLa cells activates Skp2 mRNA transcription. Using luciferase reporter and ChIP assays, we show that Stat3 binds to the promoter region of Skp2 and promotes its activity through recruiting P300. As a result of the increase of Skp2 expression, endogenous p27 protein levels are markedly decreased. Thus, our results suggest a previously unknown Stat3-Skp2 molecular network controlling cervical carcinoma development.

  11. Alkylation of cysteine 468 in Stat3 defines a novel site for therapeutic development

    PubMed Central

    Buettner, Ralf; Corzano, Renzo; Rashid, Rumana; Lin, Jianping; Senthil, Maheswari; Hedvat, Michael; Schroeder, Anne; Mao, Allen; Herrmann, Andreas; Yim, John; Li, Hongzhi; Yuan, Yate-Ching; Yakushijin, Kenichi; Yakushijin, Fumiko; Vaidehi, Nagarajan; Moore, Roger; Gugiu, Gabriel; Lee, Terry D.; Yip, Richard; Chen, Yuan; Jove, Richard; Horne, David; Williams, John C.

    2011-01-01

    Stat3 is a latent transcription factor that promotes cell survival and proliferation and is often constitutively active in multiple cancers. Inhibition of Stat3 signaling pathways suppresses cell survival signals and leads to apoptosis in cancer cells, suggesting direct inhibition of Stat3 function is a viable therapeutic approach. Herein, we identify a small molecule, C48, as a selective Stat3-family member inhibitor. To determine its mechanism of action, we used site-directed mutagenesis and multiple biochemical techniques to show that C48 alkylates Cys468 in Stat3, a residue at the DNA-binding interface. We further demonstrate that C48 blocks accumulation of activated Stat3 in the nucleus in tumor cell lines that over-express active Stat3 leading to impressive inhibition of tumor growth in mouse models. Collectively, these findings suggest Cys468 in Stat3 represents a novel site for therapeutic intervention and demonstrates the promise of alkylation as a potentially effective chemical approach for Stat3-dependent cancers. PMID:21226522

  12. Metformin Inhibits Monocyte-to-Macrophage Differentiation via AMPK-Mediated Inhibition of STAT3 Activation: Potential Role in Atherosclerosis.

    PubMed

    Vasamsetti, Sathish Babu; Karnewar, Santosh; Kanugula, Anantha Koteswararao; Thatipalli, Avinash Raj; Kumar, Jerald Mahesh; Kotamraju, Srigiridhar

    2015-06-01

    Monocyte-to-macrophage differentiation is a critical event that accentuates atherosclerosis by promoting an inflammatory environment within the vessel wall. In this study, we investigated the molecular mechanisms responsible for monocyte-to-macrophage differentiation and, subsequently, the effect of metformin in regressing angiotensin II (Ang-II)-mediated atheromatous plaque formation in ApoE(-/-) mice. AMPK activity was dose and time dependently downregulated during phorbol myristate acetate (PMA)-induced monocyte-to-macrophage differentiation, which was accompanied by an upregulation of proinflammatory cytokine production. Of note, AMPK activators metformin and AICAR significantly attenuated PMA-induced monocyte-to-macrophage differentiation and proinflammatory cytokine production. However, inhibition of AMPK activity alone by compound C was ineffective in promoting monocyte-to-macrophage differentiation in the absence of PMA. On the other hand, inhibition of c-Jun N-terminal kinase activity inhibited PMA-induced inflammation but not differentiation, suggesting that inflammation and differentiation are independent events. In contrast, inhibition of STAT3 activity inhibited both inflammation and monocyte-to-macrophage differentiation. By decreasing STAT3 phosphorylation, metformin and AICAR through increased AMPK activation caused inhibition of monocyte-to-macrophage differentiation. Metformin attenuated Ang-II-induced atheromatous plaque formation and aortic aneurysm in ApoE(-/-) mice partly by reducing monocyte infiltration. We conclude that the AMPK-STAT3 axis plays a pivotal role in regulating monocyte-to-macrophage differentiation and that by decreasing STAT3 phosphorylation through increased AMPK activity, AMPK activators inhibit monocyte-to-macrophage differentiation. PMID:25552600

  13. STAT3 inhibition sensitizes colorectal cancer to chemoradiotherapy in vitro and in vivo.

    PubMed

    Spitzner, Melanie; Roesler, Birte; Bielfeld, Christian; Emons, Georg; Gaedcke, Jochen; Wolff, Hendrik A; Rave-Fränk, Margret; Kramer, Frank; Beissbarth, Tim; Kitz, Julia; Wienands, Jürgen; Ghadimi, B Michael; Ebner, Reinhard; Ried, Thomas; Grade, Marian

    2014-02-15

    Increased activity of signal transducer and activator of transcription 3 (STAT3) is common in human malignancies, including colorectal cancers (CRCs). We have recently reported that STAT3 gene expression correlates with resistance of CRC cell lines to 5-fluorouracil (5-FU)-based chemoradiotherapy (CT/RT). This is of considerable clinical importance, because a large proportion of rectal cancers are resistant to preoperative multimodal treatment. To test whether STAT3 contributes to CT/RT-resistance, we first confirmed that STAT3 protein expression correlated positively with increasing resistance. While STAT3 was not constitutively active, stimulation with interleukin-6 (IL-6) resulted in remarkably higher expression levels of phosphorylated STAT3 in CT/RT-resistant cell lines. A similar result was observed when we determined IL-6-induced expression levels of phosphorylated STAT3 following irradiation. Next, STAT3 was inhibited in SW480 and SW837 using siRNA, shRNA and the small-molecule inhibitor STATTIC. Successful silencing and inhibition of phosphorylation was confirmed using Western blot analysis and a luciferase reporter assay. RNAi-mediated silencing as well as STATTIC treatment resulted in significantly decreased clonogenic survival following exposure to 3 µM of 5-FU and irradiation in a dose-dependent manner, with dose-modifying factors of 1.3-2.5 at a surviving fraction of 0.37. Finally, STAT3 inhibition led to a profound CT/RT-sensitization in a subcutaneous xenograft model, with a significantly delayed tumor regrowth in STATTIC-treated mice compared with control animals. These results highlight a potential role of STAT3 in mediating treatment resistance and provide first proof of concept that STAT3 represents a promising novel molecular target for sensitizing resistant rectal cancers to CT/RT. PMID:23934972

  14. FoxM1 Drives a Feed-Forward STAT3-Activation Signaling Loop That Promotes the Self-Renewal and Tumorigenicity of Glioblastoma Stem-like Cells.

    PubMed

    Gong, Ai-Hua; Wei, Ping; Zhang, Sicong; Yao, Jun; Yuan, Ying; Zhou, Ai-Dong; Lang, Frederick F; Heimberger, Amy B; Rao, Ganesh; Huang, Suyun

    2015-06-01

    The growth factor PDGF controls the development of glioblastoma (GBM), but its contribution to the function of GBM stem-like cells (GSC) has been little studied. Here, we report that the transcription factor FoxM1 promotes PDGFA-STAT3 signaling to drive GSC self-renewal and tumorigenicity. In GBM, we found a positive correlation between expression of FoxM1 and PDGF-A. In GSC and mouse neural stem cells, FoxM1 bound to the PDGF-A promoter to upregulate PDGF-A expression, acting to maintain the stem-like qualities of GSC in part through this mechanism. Analysis of the human cancer genomic database The Cancer Genome Atlas revealed that GBM expresses higher levels of STAT3, a PDGF-A effector signaling molecule, as compared with normal brain. FoxM1 regulated STAT3 transcription through interactions with the ?-catenin/TCF4 complex. FoxM1 deficiency inhibited PDGF-A and STAT3 expression in neural stem cells and GSC, abolishing their stem-like and tumorigenic properties. Further mechanistic investigations defined a FoxM1-PDGFA-STAT3 feed-forward pathway that was sufficient to confer stem-like properties to glioma cells. Collectively, our findings showed how FoxM1 activates expression of PDGF-A and STAT3 in a pathway required to maintain the self-renewal and tumorigenicity of glioma stem-like cells. Cancer Res; 75(11); 2337-48. ©2015 AACR. PMID:25832656

  15. A high-affinity protein binder that blocks the IL-6/STAT3 signaling pathway effectively suppresses non-small cell lung cancer.

    PubMed

    Lee, Joong-Jae; Kim, Hyun Jung; Yang, Chul-Su; Kyeong, Hyun-Ho; Choi, Jung-Min; Hwang, Da-Eun; Yuk, Jae-Min; Park, Keunwan; Kim, Yu Jung; Lee, Seung-Goo; Kim, Dongsup; Jo, Eun-Kyeong; Cheong, Hae-Kap; Kim, Hak-Sung

    2014-07-01

    Interleukin-6 (IL-6) is a multifunctional cytokine that regulates immune responses for host defense and tumorigenic process. Upregulation of IL-6 is known to constitutively phosphorylate signal transducer and activator of transcription 3 (STAT3), leading to activation of multiple oncogene pathways and inflammatory cascade. Here, we present the development of a high-affinity protein binder, termed repebody, which effectively suppresses non-small cell lung cancer in vivo by blocking the IL-6/STAT3 signaling. We selected a repebody that prevents human IL-6 (hIL-6) from binding to its receptor by a competitive immunoassay, and modulated its binding affinity for hIL-6 up to a picomolar range by a modular approach that mimics the combinatorial assembly of diverse modules to form antigen-specific receptors in nature. The resulting repebody was highly specific for hIL-6, effectively inhibiting the STAT3 phosphorylation in a dose- and binding affinity-response manner in vitro. The repebody was shown to have a remarkable suppression effect on the growth of tumors and STAT3 phosphorylation in xenograft mice with non-small cell lung cancer by blocking the hIL-6/STAT3 signaling. Structural analysis of the repebody and IL-6 complex revealed that the repebody binds the site 2a of hIL-6, overlapping a number of epitope residues at site 2a with gp130, and consequently causes a steric hindrance to the formation of IL-6/IL-6R? complex. Our results suggest that high-affinity repebody targeting the IL-6/STAT3 pathway can be developed as therapeutics for non-small cell lung cancer. PMID:24682171

  16. A novel 7-bromoindirubin with potent anticancer activity suppresses survival of human melanoma cells associated with inhibition of STAT3 and Akt signaling

    PubMed Central

    Liu, Lucy; Kritsanida, Marina; Magiatis, Prokopios; Gaboriaud, Nicolas; Wang, Yan; Wu, Jun; Buettner, Ralf; Yang, Fan; Nam, Sangkil; Skaltsounis, Leandros; Jove, Richard

    2012-01-01

    STAT3 and Akt signaling have been validated as potential molecular targets for treatment of cancers including melanoma. These small molecule inhibitors of STAT3 or Akt signaling are promising for developing anti-melanoma therapeutic agents. MLS-2438, a novel 7-bromoindirubin, a derivative of the natural product indirubin, was synthesized with a bromo-group at the 7-position on one indole ring and a hydrophilic group at the 3?-position on the other indole ring. We tested the anticancer activity of MLS-2438 and investigated its mechanism of action in human melanoma cell lines. Here, we show that MLS-2438 inhibits viability and induces apoptosis of human melanoma cells associated with inhibition of STAT3 and Akt signaling. Several pro-apoptotic Bcl-2 family proteins are involved in the MLS-2438 mediated apoptosis. MLS-2438 inhibits Src kinase activity in vitro and phosphorylation of JAK2, Src, STAT3 and Akt in cultured cancer cells. In contrast to the decreased phosphorylation levels of JAK2, Src, STAT3 and Akt, phosphorylation levels of the MAPK (Erk1/2) signaling protein were not reduced in cells treated with MLS-2438. These results demonstrate that MLS-2438, a novel natural product derivative, is a Src inhibitor and potentially regulates kinase activity of JAK2 and Akt in cancer cells. Importantly, MLS-2438 suppressed tumor growth with low toxicity in a mouse xenograft model of human melanoma. Our findings support further development of MLS-2438 as a potential small-molecule therapeutic agent that targets both STAT3 and Akt signaling in human melanoma cells. PMID:22895078

  17. Metformin enhances the anti-adipogenic effects of atorvastatin via modulation of STAT3 and TGF-?/Smad3 signaling.

    PubMed

    Kim, Byung-Hak; Han, Songhee; Lee, Haeri; Park, Chi Hye; Chung, Young Mee; Shin, Kyungmin; Lee, Hyun Gyu; Ye, Sang-Kyu

    2015-01-01

    Adipocyte accumulation is associated with the development of obesity and obesity-related diseases. Interactions of master transcription factors and signaling cascades are required for adipogenesis. Regulation of excessive adipogenic processes may be an attractive therapeutic for treatment of obesity and obesity-related diseases. In this study, we found that atorvastatin exerts an anti-adipogenic activity in 3T3-L1 pre-adipocytes, and that this activity is elevated in combination with metformin. Expression of the adipogenic master regulators PPAR? and C/EBP?, and their target gene aP2, was suppressed by atorvastatin. Furthermore, atorvastatin treatment resulted in increased activation of the key master regulator of cellular energy homeostasis, AMPK. These biological activities of atorvastatin were elevated in combination with metformin. These anti-adipogenic activities were associated with regulation of the STAT3 and TGF-? signaling cascades, resulting in the regulation of the expression of STAT3 target genes, such as KLF5, p53, and cyclin D1, and TGF-? signaling inhibitory genes, such as SMAD7. Our results suggest that combination therapy with atorvastatin and metformin may have therapeutic potential for the treatment of obesity and obesity-related diseases caused by excessive adipogenesis. PMID:25462562

  18. Stem cell-specific expression of Dax1 is conferred by STAT3 and Oct3/4 in embryonic stem cells

    SciTech Connect

    Sun Chuanhai [Department of Stem Cell Biology, Graduate School of Medical Science, Kanazawa University, Ishikawa 920-8640 (Japan); Nakatake, Yuhki [Laboratory for Pluripotent Cell Studies, RIKEN Center for Developmental Biology, Kobe 650-0047 (Japan); Ura, Hiroki; Akagi, Tadayuki [Department of Stem Cell Biology, Graduate School of Medical Science, Kanazawa University, Ishikawa 920-8640 (Japan); Niwa, Hitoshi [Laboratory for Pluripotent Cell Studies, RIKEN Center for Developmental Biology, Kobe 650-0047 (Japan); Koide, Hiroshi [Department of Stem Cell Biology, Graduate School of Medical Science, Kanazawa University, Ishikawa 920-8640 (Japan)], E-mail: hkoide@med.kanazawa-u.ac.jp; Yokota, Takashi [Department of Stem Cell Biology, Graduate School of Medical Science, Kanazawa University, Ishikawa 920-8640 (Japan)

    2008-07-18

    Embryonic stem (ES) cells are pluripotent cells derived from inner cell mass of blastocysts. An orphan nuclear receptor, Dax1, is specifically expressed in undifferentiated ES cells and plays an important role in their self-renewal. The regulatory mechanism of Dax1 expression in ES cells, however, remains unknown. In this study, we found that STAT3 and Oct3/4, essential transcription factors for ES cell self-renewal, are involved in the regulation of Dax1 expression. Suppression of either STAT3 or Oct3/4 resulted in down-regulation of Dax1. Reporter assay identified putative binding sites for these factors in the promoter/enhancer region of the Dax1 gene. Chromatin immunoprecipitation analysis suggested the in vivo association of STAT3 and Oct3/4 with the putative sites. Furthermore, gel shift assay indicated that these transcription factors directly bind to their putative binding sites. These results suggest that STAT3 and Oct3/4 control the expression of Dax1 to maintain the self-renewal of ES cells.

  19. Investigating Dynamics of the STAT3 and C/EBP? Pathways upon Stimulation by Inflammatory Cytokines 

    E-print Network

    Cheng, Peng

    2011-08-04

    with the specificity of the cytokine used. Future work will focus on investigating (i) dynamics of STAT3 and C/EBP? clones in response to different concentrations and durations of OSM stimulation and (ii) dynamics of STAT3 and C/EBP? clones upon exposure to additional...

  20. Targeted Disruption of the Mouse Stat3 Gene Leads to Early Embryonic Lethality

    Microsoft Academic Search

    Kiyoshi Takeda; Koichi Noguchi; Wei Shi; Takashi Tanaka; Makoto Matsumoto; Nobuaki Yoshida; Tadamitsu Kishimoto; Shizuo Akira

    1997-01-01

    Signal transducer and activator of transcription (STAT) proteins have been shown to mediate biological actions in response to cytokines. Stat3, a member of the STAT family, is activated by a variety of cytokines, including the interleukin 6 family of cytokines, leptin, granulocyte colony-stimulating factor, and epidermal growth factor. To address the biological function of Stat3, we generated mice deficient in

  1. Differences in antiproliferative effect of STAT3 inhibition in HCC cells with versus without HBV expression.

    PubMed

    Hong, Yun; Zhou, Lin; Xie, Haiyang; Wang, Weilin; Zheng, Shusen

    2015-06-01

    Chronic infection with hepatitis B virus (HBV) plays an important role in the etiology of hepatocellular carcinoma (HCC). Signal transducer and activator of transcription 3 (STAT3) inactivation could inhibit the tumor growth of HCC. In this study, differential antiproliferative effect of STAT3 inhibition was observed with HBV-related HCC cells being more resistant than non-HBV-related HCC cells. Resistance of HBV-related HCC cells to STAT3 inhibition was positively correlated to the expression of HBV. Enhanced ERK activation after STAT3 blockade was detected in HBV-related HCC cells but not in non-HBV-related HCC cells. Combined ERK and STAT3 inhibition eliminates the discrepancy between the two types of HCC cells. Moderate reduced HBV expression was found after STAT3 inhibition. These findings disclose a discrepancy in cellular response to STAT3 inhibition between non-HBV-related and HBV-related HCC cells and underscore the complexity of antiproliferative effect of STAT3 inactivation in HBV-related HCC cells. PMID:25899746

  2. Differential roles of STAT3 in the initiation and growth of lung cancer.

    PubMed

    Zhou, J; Qu, Z; Yan, S; Sun, F; Whitsett, J A; Shapiro, S D; Xiao, G

    2014-10-01

    Signal transducer and activator of transcription 3 (STAT3) is linked to multiple cancers, including pulmonary adenocarcinoma. However, the role of STAT3 in lung cancer pathogenesis has not been determined. Using lung epithelial-specific inducible knockout strategies, we demonstrate that STAT3 has contrasting roles in the initiation and growth of both chemically and genetically induced lung cancers. Selective deletion of lung epithelial STAT3 in mice before cancer induction by the smoke carcinogen, urethane, resulted in increased lung tissue damage and inflammation, K-Ras oncogenic mutations and tumorigenesis. Deletion of lung epithelial STAT3 after establishment of lung cancer inhibited cancer cell proliferation. Simultaneous deletion of STAT3 and expression of oncogenic K-Ras in mouse lung elevated pulmonary injury, inflammation and tumorigenesis, but reduced tumor growth. These studies indicate that STAT3 prevents lung cancer initiation by maintaining pulmonary homeostasis under oncogenic stress, whereas it facilitates lung cancer progression by promoting cancer cell growth. These studies also provide a mechanistic basis for targeting STAT3 to lung cancer therapy.Oncogene advance online publication, 6 October 2014; doi:10.1038/onc.2014.318. PMID:25284582

  3. Knockdown of STAT3 expression by RNAi induces apoptosis in astrocytoma cells

    PubMed Central

    Konnikova, Liza; Kotecki, Maciej; Kruger, Mathew M; Cochran, Brent H

    2003-01-01

    Background Astrocytomas are the most common type of primary central nervous system tumors. They are frequently associated with genetic mutations that deregulate cell cycle and render these tumors resistant to apoptosis. STAT3, signal transducer and activator of transcription 3, participates in several human cancers by inducing cell proliferation and inhibiting apoptosis and is frequently activated in astrocytomas. Methods RNA interference was used to knockdown STAT3 expression in human astrocytes and astrocytoma cell lines. The effect of STAT3 knockdown on apoptosis, cell proliferation, and gene expression was then assessed by standard methods. Results We have found that STAT3 is constitutively activated in several human astrocytoma cell lines. Knockdown of STAT3 expression by siRNA induces morphologic and biochemical changes consistent with apoptosis in several astrocytoma cell lines, but not in primary human astrocytes. Moreover, STAT3 is required for the expression of the antiapoptotic genes survivin and Bcl-xL in the A172 glioblastoma cell line. Conclusion These results show that STAT3 is required for the survival of some astrocytomas. These studies suggest STAT3 siRNA could be a useful therapeutic agent for the treatment of astrocytomas. PMID:13678425

  4. Stat3 Activation in Murine Colitis Induced by Enterotoxigenic Bacteroides fragilis

    PubMed Central

    Wick, Elizabeth C.; Rabizadeh, Shervin; Albesiano, Emilia; Wu, XinQun; Wu, Shaoguang; Chan, June; Rhee, Ki-Jong; Ortega, Guillermo; Huso, David L.; Pardoll, Drew; Housseau, Franck; Sears, Cynthia L.

    2014-01-01

    Background Enterotoxigenic Bacteroides fragilis (ETBF), a molecular subclass of the common human commensal, B. fragilis, has been associated with inflammatory bowel disease. ETBF colitis is characterized by the activation of Stat3 and a Th17 immune response in the colonic mucosa. This study was designed to investigate the time course and cellular distribution of Stat3 activation in ETBF-colonized mice. Methods C57BL/6 wild-type, C57BL/6Stat3?IEC, or Rag-1 mice were inoculated with saline, nontoxigenic B. fragilis or ETBF. Histologic diagnosis and mucosal Stat activation (immunohistochemistry, Western blot, and/or electrophorectic mobility shift assay) were evaluated over time (6–24 h, 1–7 d, and 1–18 mo after inoculation). Mucosal permeability was evaluated at 16 hours, 1 day, and 3 days. Mucosal immune responses were evaluated at 1 week, and 12 and 18 months. Results ETBF induced rapid-onset colitis that persisted for up to 1 year. Stat3 activation (pStat3) was noted in the mucosal immune cells within 16 hours, with colonic epithelial cell activation evident at 24 hours after inoculation. ETBF-induced increased mucosal permeability was first observed at 24 hours after inoculation, after which the initial immune cell pStat3 activation was noted. Immune cell pStat3 was present in the absence of epithelial pStat3 (C57BL/ 6Stat3?IEC). Epithelial pStat3 was present in the absence of T and B cells (Rag-1 mice). pStat3 persisted in the epithelial and immune cells for 1 year, characterized by isolated pStat3-positive cell clusters, with varying intensity distributed through the proximal and distal colon. Similarly, mucosal Th17 immune responses persisted for up to 1 year. Loss of fecal ETBF colonization was associated with the loss of mucosal pStat3 and Th17 immune responses. Conclusions ETBF rapidly induces immune cell pStat3, which is independent of epithelial pStat3. This occurs before ETBF-induced mucosal permeability, suggesting that ETBF, likely through B. fragilis toxin and its action on the colonic epithelial cell, triggers mucosal immune cell Stat3 activation. Peak mucosal Stat3 activation (immune and epithelial cells) occurs subsequently when other colonic bacteria may contribute to the ETBF-initiated immune response due to barrier dysfunction. ETBF induces long-lived, focal colonic Stat3 activation and Th17 immune responses dependent on the ongoing ETBF colonization. Further study is needed to evaluate the early mucosal signaling events, resulting in epithelial Stat3 activation and the sequelae of long-term colonic Stat3 activation. PMID:24704822

  5. Glucose-6-phosphate dehydrogenase and NADPH oxidase 4 control STAT3 activity in melanoma cells through a pathway involving reactive oxygen species, c-SRC and SHP2

    PubMed Central

    Cai, Tianchi; Kuang, Yingmin; Zhang, Chunhua; Zhang, Zheng; Chen, Long; Li, Bo; Li, Yuqian; Wang, Yanling; Yang, Huixin; Han, Qiaoqiao; Zhu, Yuechun

    2015-01-01

    Background: Glucose-6-phosphate dehydrogenase (G6PD) participates in glucose utilization by catalysing the first step of the pentose-phosphate pathway in mammalian cells. Previous studies have shown that changes in G6PD levels can promote tumor cell proliferation or apoptosis via the STAT3/5 pathway in a human melanoma xenograft model. G6PD cooperates with NADPH oxidase 4 (NOX4) in the cellular metabolism of reactive oxygen species (ROS) and in maintaining the intracellular redox state. Methods: In this study, the effect of G6PD or NOX4 silencing in the melanoma line A375 was examined in terms of redox state, proto-oncogene tyrosine-protein kinase Src (c-Src) and the tyrosine-specific protein phosphatase SHP2 expression as well as cell cycle progression. Results: The results demonstrate that: (1) Downregulation of cyclin D1 and CDK4 and up-regulation of p53 and p21 occurred in response to silencing of G6PD and NOX4 thus resulting in G1/S cell cycle arrest and inhibition of A375 cell proliferation. (2) The blockade of cell proliferation is primarily due to a reduced DNA-binding activity of STAT3. (3) The DNA-binding activity of STAT3 was regulated by the upstream factors, c-SRC and SHP2. Silencing of NOX4 in A375 cells inhibited c-SRC and SHP2 regulated STAT3 activity. Conclusion: The data are consistent with a novel G6PD-NOX4-NADPH-ROS-c-SRC/SHP2 pathway controlling STAT3 activity in A375 melanoma cells.

  6. Suppression of JAK2/STAT3 Signaling Reduces End-to-End Arterial Anastomosis Induced Cell Proliferation in Common Carotid Arteries of Rats

    PubMed Central

    Zhao, Jinbing; Zhang, Meijuan; Li, Wei; Su, Xingfen; Zhu, Lin; Hang, Chunhua

    2013-01-01

    Background JAK2/STAT3 pathway was reported to play an essential role in the neointima formation after vascular intima injury. However, little is known regarding this pathway to the whole layer injury after end-to-end arterial anastomosis (AA). Here, we investigated the role of JAK2/STAT3 pathway in common carotid arterial (CCA) anastomosis-induced cell proliferation, phenotypic change of vascular smooth muscle cells (VSMCs) and re-endothelialization. Methods CCAs of adult male Wistar rats were resected at 3, 7, 14, and 30 days after end-to-end CCA anastomosis. Activation of JAK2/STAT3 pathway was detected by Western blotting and Immunofluorescence, and expression of proliferating cell nuclear antigen (PCNA) was detected by Q-PCR and Western blotting. Under the treatment with AG490 (a JAK2 inhibitor), protein levels of JAK2, STAT3 and PCNA, morphological changes of artery, phenotypic change of VSMCs, and re-endothelialization were measured by Western blotting, H&E, Q-PCR, and Evans blue staining respectively. Results The protein levels of p-JAK2, p-STAT3, and PCNA were up-regulated, peaked on the 7th day in the vessel wall after AA. AG490 down-regulated the levels of p-JAK2, p-STAT3, and PCNA on the 7th-day-group, resulting in reduced vessel wall proliferation on the 7th and 14th day after AA. Besides, AG490 switched the phenotypic change of VSMCs after AA representing inhibited mRNA levels of synthetic phase markers (osteopoitin and SMemb) and up-regulated contractile phase markers (ASMA, SM2 and SM22?). Furthermore, AG490 did not affect the re-endothelialization process on all indicated time points after AA (the 3rd, 7th, 14th, and 30th day). Conclusion Our study indicated that JAK2/STAT3 signaling pathway played an important role on cell proliferation of the injured vessel wall, and probably a promising target for the exploration of drugs increasing the patency or reducing the vascular narrowness after AA. PMID:23516544

  7. Carbon Monoxide Induces Heme Oxygenase-1 to Modulate STAT3 Activation in Endothelial Cells via S-Glutathionylation

    PubMed Central

    Yang, Yan-Chang; Huang, Yu-Ting; Hsieh, Chia-Wen; Yang, Po-Min; Wung, Being-Sun

    2014-01-01

    IL-6/STAT3 pathway is involved in a variety of biological responses, including cell proliferation, differentiation, apoptosis, and inflammation. In our present study, we found that CO releasing molecules (CORMs) suppress IL-6-induced STAT3 phosphorylation, nuclear translocation and transactivity in endothelial cells (ECs). CO is a byproduct of heme degradation mediated by heme oxygenase (HO-1). However, CORMs can induce HO-1 expression and then inhibit STAT3 phosphorylation. CO has been found to increase a low level ROS and which may induce protein glutathionylation. We hypothesized that CORMs increases protein glutathionylation and inhibits STAT3 activation. We found that CORMs increase the intracellular GSSG level and induce the glutathionylation of multiple proteins including STAT3. GSSG can inhibit STAT3 phosphorylation and increase STAT3 glutathionylation whereas the antioxidant enzyme catalase can suppress the glutathionylation. Furthermore, catalase blocks the inhibition of STAT3 phosphorylation by CORMs treatment. The inhibition of glutathione synthesis by BSO was also found to attenuate STAT3 glutathionylation and its inhibition of STAT3 phosphorylation. We further found that HO-1 increases STAT3 glutathionylation and that HO-1 siRNA attenuates CORM-induced STAT3 glutathionylation. Hence, the inhibition of STAT3 activation is likely to occur via a CO-mediated increase in the GSSG level, which augments protein glutathionylation, and CO-induced HO-1 expression, which may enhance and maintain its effects in IL-6-treated ECs. PMID:25072782

  8. Critical role of STAT3 in melanoma metastasis through anoikis resistance

    PubMed Central

    Fofaria, Neel M.; Srivastava, Sanjay K.

    2014-01-01

    Anoikis is an anchorage-independent cell death. Resistance to anoikis is one of the key features of metastatic cells. Here, we analyzed the role of STAT3 in anoikis resistance in melanoma cells leading to metastasis. When grown under anchorage-independent conditions, significant proportion of cells resisted anoikis and these resistant cells had higher rate of migration and invasion as compared to the cells grown under anchorage-dependent conditions. The anoikis resistant cells also had significantly higher expression and phosphorylation of STAT3 at Y705 than the cells that were attached to the basement membrane. STAT3 inhibitors, AG 490 and piplartine (PL) induced anoikis in a concentration-dependent manner in anoikis resistant cells. Over-expression of STAT3 or treatment with IL-6 not only increased anoikis resistance, but also protected the cancer cells from PL-induced anoikis. On the other hand, silencing STAT3 decreased the potential of cancer cells to resist anoikis and to migrate. STAT3 knock-down cells and PL treated cells did not form tumors as well as failed to metastasize in SCID-NSG mice as compared to untreated anchorage-independent cells, which formed big tumors and extensively metastasized. In summary, our results for the first time establish STAT3 as a critical player that renders anoikis resistance to melanoma cells and enhance their metastatic potential. PMID:25216522

  9. T-cell STAT3 is required for the maintenance of humoral immunity to LCMV

    PubMed Central

    McIlwain, David R; Grusdat, Melanie; Pozdeev, Vitaly I; Xu, Haifeng C; Shinde, Prashant; Reardon, Colin; Hao, Zhenyue; Beyer, Marc; Bergthaler, Andreas; Häussinger, Dieter; Nolan, Garry P; Lang, Karl S; Lang, Philipp A

    2015-01-01

    STAT3 is a critical transcription factor activated downstream of cytokine signaling and is integral for the function of multiple immune cell types. Human mutations in STAT3 cause primary immunodeficiency resulting in impaired control of a variety of infections, including reactivation of latent viruses. In this study, we investigate how T-cell functions of STAT3 contribute to responses to viral infection by inducing chronic lymphocytic choriomeningitis virus (LCMV) infection in mice lacking STAT3 specifically in T cells. Although mice with conditional disruption of STAT3 in T cells were able to mount early responses to viral infection similar to control animals, including expansion of effector T cells, we found generation of T-follicular helper (Tfh) cells to be impaired. As a result, STAT3 T cell deficient mice produced attenuated germinal center reactions, and did not accumulate bone marrow virus specific IgG-secreting cells, resulting in failure to maintain levels of virus-specific IgG or mount neutralizing responses to LCMV in the serum. These effects were associated with reduced control of viral replication and prolonged infection. Our results demonstrate the importance of STAT3 in T cells for the generation of functional long-term humoral immunity to viral infections. PMID:25393615

  10. Roles of STAT3 in protein secretion pathways during the acute-phase response.

    PubMed

    Ahyi, Ayele-Nati N; Quinton, Lee J; Jones, Matthew R; Ferrari, Joseph D; Pepper-Cunningham, Zachary A; Mella, Juan R; Remick, Daniel G; Mizgerd, Joseph P

    2013-05-01

    The acute-phase response is characteristic of perhaps all infections, including bacterial pneumonia. In conjunction with the acute-phase response, additional biological pathways are induced in the liver and are dependent on the transcription factors STAT3 and NF-?B, but these responses are poorly understood. Here, we demonstrate that pneumococcal pneumonia and other severe infections increase expression of multiple components of the cellular secretory machinery in the mouse liver, including the endoplasmic reticulum (ER) translocon complex, which mediates protein translation into the ER, and the coat protein complexes (COPI and COPII), which mediate vesicular transport of proteins to and from the ER. Hepatocyte-specific mutation of STAT3 prevented the induction of these secretory pathways during pneumonia, with similar results observed following pharmacological activation of ER stress by using tunicamycin. These findings implicate STAT3 in the unfolded protein response and suggest that STAT3-dependent optimization of secretion may apply broadly. Pneumonia also stimulated the binding of phosphorylated STAT3 to promoter regions of secretion-related genes in the liver, supporting a direct role for STAT3 in their transcription. Altogether, these results identify a novel function of STAT3 during the acute-phase response, namely, the induction of secretory machinery in hepatocytes. This may facilitate the processing and delivery of newly synthesized loads of acute-phase proteins, enhancing innate immunity and preventing liver injury during infection. PMID:23460517

  11. Correlation of RKIP, STAT3 and cyclin D1 expression in pathogenesis of gastric cancer

    PubMed Central

    Zhang, Xiao-Mei; Zhou, Chuanwen; Gu, Huan; Yan, Lu; Zhang, Gui-Ying

    2014-01-01

    RKIP is proposed as a new metastasis suppressor. Our recent study showed that RKIP inhibits malignant phenotypes of gastric cancer cells. However, the underlying mechanism of RKIP function in gastric cancer is unclear. This study aimed to investigate the correlation of RKIP, STAT3 and cyclin D1 expression in the tumorigenesis of gastric cancer. RKIP, STAT3 and cyclin D1 proteins were detected by immunohistochemistry in tissues of gastric ulcer (n = 27), gastric adenomatous polyp (n = 7), intestinal metaplasia (n = 26), dysplasia (n = 40), gastric carcinoma (n = 169) and metastatic lymph node (n = 36). RKIP, STAT3 and cyclin D1 mRNA levels were analyzed by RT-PCR in SGC7901 cells. We found that RKIP protein expression was significantly decreased in advanced gastric cancer and metastatic lymph node tissues while cyclin D1 and STAT3 protein expression was markedly increased in severe dysplasia, gastric cancer and metastatic lymph node tissue (P < 0.01). RKIP expression in gastric cancer was negatively correlated with the invasion, TNM stage and lymphoid node metastasis (P < 0.01), while cyclin D1 and STAT3 expression was positively correlated with histological differentiation and lymphoid node metastasis (P < 0.01). RKIP protein level was negatively correlated with cyclin D1 and STAT3 protein level, while cyclin D1 protein level was positively correlated with STAT3 protein level in gastric cancer samples. Moreover, reconstitution of RKIP in SGC7901 gastric cancer cells led to reduced cyclin D1 and STAT3 mRNA levels. In conclusion, these data suggest that RKIP inhibits gastric cancer metastasis via the downregulation of its downstream target genes STAT3 and cyclin D1. PMID:25337233

  12. STAT3 supports experimental K-RasG12D-induced murine myeloproliferative neoplasms dependent on serine phosphorylation.

    PubMed

    Gough, Daniel J; Marié, Isabelle J; Lobry, Camille; Aifantis, Iannis; Levy, David E

    2014-10-01

    Juvenile myelomonocytic leukemia, acute myeloid leukemia (AML), and other myeloproliferative neoplasms (MPNs) are genetically heterogeneous but frequently display activating mutations in Ras GTPases and activation of signal transducer and activator of transcription 3 (STAT3). Altered STAT3 activity is observed in up to 50% of AML correlating with poor prognosis. Activated STAT proteins, classically associated with tyrosine phosphorylation, support tumor development as transcription factors, but alternative STAT functions independent of tyrosine phosphorylation have been documented, including roles for serine-phosphorylated STAT3 in mitochondria supporting transformation by oncogenic Ras. We examined requirements for STAT3 in experimental murine K-Ras-dependent hematopoietic neoplasia. We show that STAT3 is phosphorylated on S727 but not Y705 in diseased animals. Moreover, a mouse with a point mutation abrogating STAT3 S727 phosphorylation displayed delayed onset and decreased disease severity with significantly extended survival. Activated K-Ras required STAT3 for cytokine-independent growth of myeloid progenitors in vitro, and mitochondrially restricted STAT3 and STAT3-Y705F, both transcriptionally inert mutants, supported factor-independent growth. STAT3 was dispensable for growth of normal or K-Ras-mutant myeloid progenitors in response to cytokines. However, abrogation of STAT3-S727 phosphorylation impaired factor-independent malignant growth. These data document that serine-phosphorylated mitochondrial STAT3 supports neoplastic hematopoietic cell growth induced by K-Ras. PMID:25150294

  13. Ponicidin Induces Apoptosis via JAK2 and STAT3 Signaling Pathways in Gastric Carcinoma

    PubMed Central

    Liu, Yuan-Fei; Lu, Yun-Min; Qu, Guo-Qiang; Liu, Yuan; Chen, Wei-Xiong; Liao, Xiao-Hong; Kong, Wu-Ming

    2015-01-01

    Ponicidin has a variety of biological effects such as immunoregulatory and anti-inflammatory functions as well as anti-viral functions especially in the upper respiratory tract infection. This study was aimed to elucidate the antitumor effect of ponicidin in gastric carcinoma MKN28 cells and the possible molecular mechanism involved. Cell viability was measured by the Cell Count Kit-8 (CCK8). Cell apoptosis was assessed by flow cytometry as well as cell cycle and reactive oxygen species (ROS) analysis. Western blot analysis was used to detect the active form of caspase-3 as well as Bax and B-cell lymphoma-2 (Bcl-2) expressions after cells were treated with different concentrations of ponicidin. The results revealed that ponicidin could inhibit the growth of MKN28 cells significantly in both a time- and dose-dependent manner. The cell cycle was blocked and ROS generation was increased after the cells were treated with ponicidin. Bcl-2 expression was down-regulated remarkably while Bax expression and the active form of caspase-3 were increased after apoptosis occurred. We therefore conclude that ponicidin exhibited significant growth inhibition of gastric carcinoma cell line MKN28 and induced apoptosis of MKN28 cells via the signaling pathway regulated by Janus kinase 2 (JAK2) and signal transducers and activators of transcription 3 (STAT3). Ponicidin may serve as a potential therapeutic agent for gastric carcinoma. PMID:25588213

  14. Inhibitory effect of ent-Sauchinone on amyloidogenesis via inhibition of STAT3-mediated NF-?B activation in cultured astrocytes and microglial BV-2 cells

    PubMed Central

    2014-01-01

    Background ent-Sauchinone is a polyphenolic compound found in plants belonging to the lignan family. ent-Sauchinone has been shown to modulate the expression of inflammatory factors through the nuclear factor-kappa B (NF-?B) signaling pathway. It is well known that neuroinflammation is associated with amyloidogenesis. Thus, in the present study, we investigated whether ent-Sauchinone could have anti-amyloidogenic effects through the inhibition of NF-?B pathways via its anti-inflammatory property. Methods To investigate the potential effect of ent-Sauchinone on anti-neuroinflammation and anti-amyloidogenesis in in vitro studies, we used microglial BV-2 cells and cultured astrocytes treated with ent-Sauchinone (1, 5, and 10 ?M) for 24 hours. For the detection of anti-neuro-inflammatory responses, reative oxygen species (ROS) and Nitric oxide (NO) generation and inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression were measured with assay kits and western blotting. ?-secretase and ?-secretase activities and ?-amyloid levels were determined for measuring the anti-amyloidogenic effects of ent-Sauchinone by enzyme assay kits. NF-?B and STAT3 signals were detected with electromobility shift assay (EMSA) to study the related signaling pathways. The binding of ent-Sauchinone to STAT3 was evaluated by a pull-down assay and by a docking model using Autodock VINA software (Hoover’s Inc., Texas, United states). Results ent-Sauchinone (1, 5, and 10 ?M) effectively decreased lipopolysaccharide (LPS)-(1 ?g/ml) induced inflammatory responses through the reduction of ROS and NO generations and iNOS and COX-2 expressions in cultured astrocytes and microglial BV-2 cells. ent-Sauchinone also inhibited LPS-induced amyloidogenesis through the inhibition of ?-secretase and ?-secretase activity. NF- ?B amyloid and STAT3, critical transcriptional factors regulating not only inflammation but also amyloidogenesis, were also inhibited in a concentration dependent manner by ent-Sauchinone by blocking the phosphorylation of I ?B and STAT3 in cultured astrocytes and microglial BV-2 cells. The docking model approach showed that ent-Sauchinone binds to STAT3, and the employment of a STAT3 inhibitor and siRNA reversed ent-Sauchinone-induced inhibition NF-?B activation and A? generation. Conclusions These results indicated that ent-Sauchinone inhibited neuroinflammation and amyloidogenesis through the inhibition of STAT3-mediated NF-?B activity, and thus could be applied in the treatment of neuro-inflammatory diseases, including Alzheimer’s disease. PMID:24985096

  15. Novel synthetic derivatives of the natural product berbamine inhibit Jak2/Stat3 signaling and induce apoptosis of human melanoma cells

    PubMed Central

    Nam, Sangkil; Xie, Jun; Perkins, Angela; Ma, Yuelong; Yang, Fan; Wu, Jun; Wang, Yan; Xu, Rong-zhen; Huang, Wendong; Horne, David A.; Jove, Richard

    2012-01-01

    Persistent Jak/Stat3 signal transduction plays a crucial role in tumorigenesis and immune development. Activated Jak/Stat3 signaling has been validated as a promising molecular target for cancer therapeutics discovery and development. Berbamine (BBM), a natural bis-benzylisoquinoline alkaloid, was identified from the traditional Chinese herbal medicine Berberis amurensis used for treatment of cancer patients. While BBM has been shown to have potent antitumor activities with low toxicity in various cancer types, the molecular mechanism of action of BBM remains largely unknown. Here, we determine the antitumor activities of thirteen synthetic berbamine derivatives (BBMDs) against human solid tumor cells. BBMD3, which is the most potent in this series of novel BBMDs, exhibits over 6-fold increase in biological activity compared to natural BBM. Moreover, BBMD3, directly inhibits Jak2 autophosphorylation kinase activity in vitro with IC50 = 0.69 ?M. Autophosphorylation of Jak2 kinase at Tyr1007/1008 sites also was strongly inhibited in the range of 1 ?M to 5 ?M of BBMD3 in human melanoma cells at 4 h after treatment. Following inhibition of autophosphorylation of Jak2, BBMD3 blocked constitutive activation of downstream Stat3 signaling in melanoma cells. BBMD3 also down-regulated expression of the Stat3 target proteins Mcl-1 and Bcl-xL, associated with induction of apoptosis. In sum, our findings demonstrate that the novel berbamine derivative BBMD3 is an inhibitor of the Jak2/Stat3 signaling pathway, providing evidence for a molecular mechanism whereby BBMD3 exerts at least in part the apoptosis of human melanoma cells. In addition, BBMD3 represents a promising lead compound for development of new therapeutics for cancer treatment. PMID:22717603

  16. Exosomal Hsp70 mediates immunosuppressive activity of the myeloid-derived suppressor cells via phosphorylation of Stat3.

    PubMed

    Diao, Jianjun; Yang, Xue; Song, Xuedong; Chen, Shiyou; He, Yunfeng; Wang, Qingsong; Chen, Gang; Luo, Chunli; Wu, Xiaohou; Zhang, Yao

    2015-02-01

    Myeloid-derived suppressor cells (MDSCs), one of the main cell populations, are responsible for regulating the immune response, which accumulates in tumor-bearing mice and humans contributing to cancer development. Exosomes produced by tumor cells have been involved in tumor-associated immune suppression. However, the role of exosomes is unclear in the activation of MDSCs. Here, we have purified tumor-derived exosomes from the supernatants of Renca cell cultures. Transmission electron microscopy was used to confirm their morphology, and Western blot analysis showed that Hsp70 was rich in these isolated exosomes compared with the whole-cell lysates of Renca cells. Then, we demonstrated that there was a more powerful activity of exosomal Hsp70-mediated induction of proinflammation cytokines, tumor growth factors of MDSCs and tumor progression than exosomes pre-incubated with anti-Hsp70 antibody. Furthermore, we show that an interactive exosomal HSP70 and MDSCs determine the suppressive activity of the MDSCs via phosphorylation of Stat3 (p-Stat3). Finally, we show that exosomal Hsp70 triggers p-Stat3 in MDSCs in a TLR2-MyD88-dependent manner. Meanwhile, we also find that there is a more significant increase in the percentage of CD11b+Gr-1+ cells in the mice, which are treated with exosomal Hsp70 than that exosomes pre-incubated with anti-Hsp70 antibody. Hence, we believe that the signaling pathway activation by exosomal Hsp70 within MDSCs may be a significant target in future treatment of renal cell carcinoma. PMID:25603952

  17. Emerging translational approaches to target STAT3 signalling and its impact on vascular disease

    PubMed Central

    Dutzmann, Jochen; Daniel, Jan-Marcus; Bauersachs, Johann; Hilfiker-Kleiner, Denise; Sedding, Daniel G.

    2015-01-01

    Acute and chronic inflammation responses characterize the vascular remodelling processes in atherosclerosis, restenosis, pulmonary arterial hypertension, and angiogenesis. The functional and phenotypic changes in diverse vascular cell types are mediated by complex signalling cascades that initiate and control genetic reprogramming. The signalling molecule's signal transducer and activator of transcription 3 (STAT3) plays a key role in the initiation and continuation of these pathophysiological changes. This review highlights the pivotal involvement of STAT3 in pathological vascular remodelling processes and discusses potential translational therapies, which target STAT3 signalling, to prevent and treat cardiovascular diseases. Moreover, current clinical trials using highly effective and selective inhibitors of STAT3 signalling for distinct diseases, such as myelofibrosis and rheumatoid arthritis, are discussed with regard to their vascular (side-) effects and their potential to pave the way for a direct use of these molecules for the prevention or treatment of vascular diseases. PMID:25784694

  18. Convergent mutations and kinase fusions lead to oncogenic STAT3 activation in anaplastic large cell lymphoma.

    PubMed

    Crescenzo, Ramona; Abate, Francesco; Lasorsa, Elena; Tabbo', Fabrizio; Gaudiano, Marcello; Chiesa, Nicoletta; Di Giacomo, Filomena; Spaccarotella, Elisa; Barbarossa, Luigi; Ercole, Elisabetta; Todaro, Maria; Boi, Michela; Acquaviva, Andrea; Ficarra, Elisa; Novero, Domenico; Rinaldi, Andrea; Tousseyn, Thomas; Rosenwald, Andreas; Kenner, Lukas; Cerroni, Lorenzo; Tzankov, Alexander; Ponzoni, Maurilio; Paulli, Marco; Weisenburger, Dennis; Chan, Wing C; Iqbal, Javeed; Piris, Miguel A; Zamo', Alberto; Ciardullo, Carmela; Rossi, Davide; Gaidano, Gianluca; Pileri, Stefano; Tiacci, Enrico; Falini, Brunangelo; Shultz, Leonard D; Mevellec, Laurence; Vialard, Jorge E; Piva, Roberto; Bertoni, Francesco; Rabadan, Raul; Inghirami, Giorgio

    2015-04-13

    A systematic characterization of the genetic alterations driving ALCLs has not been performed. By integrating massive sequencing strategies, we provide a comprehensive characterization of driver genetic alterations (somatic point mutations, copy number alterations, and gene fusions) in ALK(-) ALCLs. We identified activating mutations of JAK1 and/or STAT3 genes in ?20% of 155 ALK(-) ALCLs and demonstrated that 38% of systemic ALK(-) ALCLs displayed double lesions. Recurrent chimeras combining a transcription factor (NFkB2 or NCOR2) with a tyrosine kinase (ROS1 or TYK2) were also discovered in WT JAK1/STAT3 ALK(-) ALCL. All these aberrations lead to the constitutive activation of the JAK/STAT3 pathway, which was proved oncogenic. Consistently, JAK/STAT3 pathway inhibition impaired cell growth in vitro and in vivo. PMID:25873174

  19. Dehydroepiandrosterone inhibits the Src/STAT3 constitutive activation in pulmonary arterial hypertension.

    PubMed

    Paulin, Roxane; Meloche, Jolyane; Jacob, Maria Helena; Bisserier, Malik; Courboulin, Audrey; Bonnet, Sébastien

    2011-11-01

    Pulmonary arterial hypertension (PAH) is an obstructive vasculopathy characterized by enhanced pulmonary artery smooth muscle cell (PASMC) proliferation and suppressed apoptosis. This phenotype is sustained by the activation of the Src/signal transducer and activator of transcription 3 (STAT3) axis, maintained by a positive feedback loop involving miR-204 and followed by an aberrant expression/activation of its downstream targets such as Pim1 and nuclear factor of activated T-cells (NFATc2). Dehydroepiandrosterone (DHEA) is a steroid hormone shown to reverse vascular remodeling in systemic vessels. Since STAT3 has been described as modulated by DHEA, we hypothesized that DHEA reverses human pulmonary hypertension by inhibiting Src/STAT3 constitutive activation. Using PASMCs isolated from patients with PAH (n = 3), we demonstrated that DHEA decreases both Src and STAT3 activation (Western blot and nuclear translocation assay), resulting in a significant reduction of Pim1, NFATc2 expression/activation (quantitative RT-PCR and Western blot), as well as Survivin and upregulation of bone morphogenetic protein receptor 2 (BMPR2) and miR-204. Src/STAT3 axis inhibition by DHEA is associated with 1) mitochondrial membrane potential (tetramethylrhodamine methyl-ester perchlorate; n = 150; P < 0.05) depolarization increasing apoptosis by 25% (terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling; n = 150; P < 0.05); and 2) decreased intracellular Ca(2+) concentration (fluo-3 AM; n = 150; P < 0.05) and proliferation by 30% (PCNA). Finally, in vivo similarly to STAT3 inhibition DHEA improves experimental PAH (monocrotaline rats) by decreasing mean PA pressure and right ventricle hypertrophy. These effects were associated with the inhibition of Src, STAT3, Pim1, NFATc2, and Survivin and the upregulation of BMPR2 and miR-204. We demonstrated that DHEA reverses pulmonary hypertension in part by inhibiting the Src/STAT3. PMID:21890685

  20. LLL12, a novel small inhibitor targeting STAT3 for hepatocellular carcinoma therapy.

    PubMed

    Zuo, Mingxin; Li, Chenglong; Lin, Jiayuh; Javle, Milind

    2015-05-10

    The constitutive activation of signal transducer and activator of transcription 3 (STAT3) is frequently detected in clinical incidences of hepatocellular carcinoma (HCC) but not in normal human hepatocytes. STAT3 signaling plays pivotal roles in angiogenesis, survival, metastasis, and growth of HCC. Recent evidence suggests that the blockade of aberrant STAT3 pathways can be exploited as a therapeutic strategy for HCC. We have developed the novel small molecular STAT3 inhibitor LLL12 on the basis of curcumin structure using computer-aided rational design. LLL12 has shown antitumor activity in various solid tumors including breast, brain, pancreatic cancer, and glioblastoma in vitro and in vivo. In this study, we hypothesized LLL12 inhibits STAT3 phosphorylation at tyrosine 705 (Y705) in HCC and show antitumor activity in HCC in vitro and in vivo. Our results show that LLL12 selectively inhibited HCC cell proliferation and induced apoptosis in SNU387, SNU398, SNU449, and Hep3B HCC cells in vitro. Furthermore, LLL12 at 5 mg/kg/day significantly inhibited the growth of SNU398 xenografts in nude mice. Collectively, our results indicate that LLL12 could be used to target STAT3 for the effective prevention or treatment of HCC. PMID:25883212

  1. Fas Signaling Promotes Gastric Cancer Metastasis through STAT3-Dependent Upregulation of Fascin

    PubMed Central

    Cai, Zhijian; Cheng, Guoping; Chen, Ming; Wang, Jiaoli; Zhong, Haijun

    2015-01-01

    Background Fas signaling-activated signal transducers and activators of transcription 3 (STAT3) is required for Fascin upregulation. As an actin-bundling protein, Fascin can mediate gastric cancer (GC) cell migration. Methods Gastric cancer AGS cells were treated with anti-Fas (5 ?g/ml) for 2 h, in order to stimulate the activation of the Fas signaling. The in vitro migration of Fas signaling-activated AGS cells was assessed using Transwell chambers. The levels of Fascin and phosphorylated STAT3 were detected by Western blotting analyses. Nude mice were injected intravenously with AGS cells treated with anti-Fas or treated with STAT3 inhibitor without anti-Fas; tumor pulmonary metastases were measured. Fascin protein expression in tumor tissues was detected by immunohistochemistry. The Fas and Fascin mRNA levels in tumor tissues from patients with GC were measured by real-time PCR and their correlation was analyzed. Results The activation of Fas signaling promoted cell migration and resulted in STAT3-dependent Fascin upregulation in AGS cells. STAT3 enhanced Fascin levels in vivo. Fascin was the mediator of Fas signaling-induced AGS cell migration in vitro and in vivo. Furthermore, there was a positive correlation between Fas and Fascin mRNA levels in tumor tissues from GC patients. Conclusions Fas signaling promotes GC metastasis through the STAT3/Fascin pathway, which may provide a new target for GC therapy. PMID:25992623

  2. Inhibition of the JAK2/STAT3 signaling pathway exerts a therapeutic effect on osteosarcoma.

    PubMed

    Yan, Jun; Wang, Qianliang; Zou, Kang; Wang, Li; Schwartz, Eric B; Fuchs, James R; Zheng, Zugen; Wu, Jianqiang

    2015-07-01

    Osteosarcoma (OS) is the most common type of malignant bone tumor. Despite aggressive multimodal treatments, including surgical resection, chemotherapy and adjunctive immunotherapies, patients with OS with high-grade malignancy have a poor five-year survival rate that has remained unchanged over the past two decades, highlighting the urgent requirement for novel therapeutic approaches. Signal transducers and activators of transcription 3 (STAT3) has been implicated as an oncogene and therapeutic target in a variety of neoplastic diseases. The aim of the present study was to determine whether inhibition of the janus kinase 2 (JAK2)/STAT3 pathway by FLLL32, a specific JAK2/STAT3 inhibitor, is able to provide a potential therapy for OS. FLLL32 inhibited OS cell growth in vitro and delayed OS growth in an OS xenograft nude mouse model. STAT3 knockdown by short hairpin RNA delayed OS formation in vivo. Thus, the JAK2/STAT3 pathway is important in OS formation. Efficacy of the FLLL32 pharmacological inhibitor in delaying OS growth suggests that targeting JAK2/STAT3 may be a potential therapeutic strategy for patients with OS. PMID:25760445

  3. LLL12, a novel small inhibitor targeting STAT3 for hepatocellular carcinoma therapy

    PubMed Central

    Zuo, Mingxin; Li, Chenglong; Lin, Jiayuh; Javle, Milind

    2015-01-01

    The constitutive activation of signal transducer and activator of transcription 3 (STAT3) is frequently detected in clinical incidences of hepatocellular carcinoma (HCC) but not in normal human hepatocytes. STAT3 signaling plays pivotal roles in angiogenesis, survival, metastasis, and growth of HCC. Recent evidence suggests that the blockade of aberrant STAT3 pathways can be exploited as a therapeutic strategy for HCC. We have developed the novel small molecular STAT3 inhibitor LLL12 on the basis of curcumin structure using computer-aided rational design. LLL12 has shown antitumor activity in various solid tumors including breast, brain, pancreatic cancer, and glioblastoma in vitro and in vivo. In this study, we hypothesized LLL12 inhibits STAT3 phosphorylation at tyrosine 705 (Y705) in HCC and show antitumor activity in HCC in vitro and in vivo. Our results show that LLL12 selectively inhibited HCC cell proliferation and induced apoptosis in SNU387, SNU398, SNU449, and Hep3B HCC cells in vitro. Furthermore, LLL12 at 5 mg/kg/day significantly inhibited the growth of SNU398 xenografts in nude mice. Collectively, our results indicate that LLL12 could be used to target STAT3 for the effective prevention or treatment of HCC. PMID:25883212

  4. Everolimus-induced human keratinocytes toxicity is mediated by STAT3 inhibition

    PubMed Central

    2013-01-01

    Background Mammalian target of rapamycin (mTOR) inhibitors are associated with dermatological adverse events. The chief aim of this study was to examine the relation between the signal transducer and activator of transcription 3 (STAT3) protein and the dermatological adverse events associated with the mTOR inhibitor everolimus. Methods We evaluated the effects of STAT3 activity and related signal transduction activities on everolimus-induced cell growth inhibition in the human keratinocyte HaCaT cell line via a WST-8 assay, and on signal transduction mechanisms involved in everolimus treatments via a western blot analysis. Apoptosis was evaluated using an imaging cytometric assay. Results The cell growth inhibitory effects of everolimus were enhanced by stattic or STA-21, which are selective inhibitors of STAT3, treatment in HaCaT cells, although such effects were not observed in Caki-1 and HepG2 cells. Phosphorylation at tyrosine 705 of STAT3 was decreased by treatment with everolimus in a dose-dependent manner in HaCaT cells; in contrast, phosphorylation at serine 727 was not decreased by everolimus, but slightly increased. Furthermore, we found that pretreatment of p38 MAPK inhibitor and transfection with constitutively active form of STAT3 in HaCaT cells resisted the cytostatic activity of everolimus. Conclusions These findings suggest that STAT3 activity may be a biomarker of everolimus-induced dermatological toxicity. PMID:24423131

  5. Analysis of Signal Transducer and Activator of Transcription 3 (Stat 3) Pathway in Multiple Myeloma

    PubMed Central

    Quintanilla-Martinez, Leticia; Kremer, Marcus; Specht, Katja; Calzada-Wack, Julia; Nathrath, Michaela; Schaich, Robert; Höfler, Heinz; Fend, Falko

    2003-01-01

    The signal transducer and activator of transcription molecules (Stats) play key roles in cytokine-induced signal transduction. Recently, it was proposed that constitutively activated Stat 3 (Stat 3 phosphorylated) contributes to the pathogenesis of multiple myeloma (MM) by preventing apoptosis and inducing proliferation. The study aim was to investigate Stat 3 activation in a series of multiple myeloma (MM) cases and its effect on downstream targets such as the anti-apoptotic proteins Bcl-xL, Mcl-1, and Bcl-2, and the cell-cycle protein cyclin D1. Forty-eight cases of MM were analyzed. Immunohistochemistry was performed on paraffin sections using antibodies against cyclin D1, Bcl-2, Bcl-xL, Mcl-1, p21, Stat 3, and Stat 3 phosphorylated (P). Their specificity was corroborated by Western blot analysis using eight human MM cell lines as control. The proliferation rate was assessed with the antibody MiB1. In addition, the mRNA levels of cyclin D1 and Stat 3 were determined by quantitative real-time reverse transcriptase-polymerase chain reaction of paraffin-embedded microdissected tissue. Three different groups determined by the expression of Stat 3P and cyclin D1 (protein and mRNA) were identified: group 1, Stat 3-activated (23 cases, 48%). All cases revealed nuclear expression of Stat 3P. No elevation of Stat 3 mRNA was identified in any of the cases. Three cases in this group showed intermediate to low cyclin D1 protein and mRNA expression. Group 2 included 15 (31%) cases with cyclin D1 staining and lack of Stat 3P. All cases showed intermediate to high levels of cyclin D1 mRNA expression. Group 3 included 10 (21%) cases with no expression of either cyclin D1 or Stat 3P. High levels of anti-apoptotic proteins Bcl-xL and Mcl-1 were identified in 89% and 100% of all cases, respectively. In contrast to Bcl-xL and Mcl-1, the expression of Bcl-2 showed an inverse correlation with proliferation rate (P: 0.0003). No significant differences were found between the three groups in terms of proliferation rate or expression of anti-apoptotic proteins. However, cyclin D1+ cases were always well differentiated and were more likely to show a lymphoplasmocytoid differentiation (chi-square = 9.55). Overall, constitutive activation of Stat 3 was found in almost half (48%) of the investigated MM cases. However, this does not seem to have a major impact on the expression of anti-apoptotic proteins and proliferation. We showed that cyclin D1 overexpression and Stat 3 activation are, mutually exclusive events in MM (P = 0.0066). The universal expression of Mcl-1, independent of activated Stat 3, suggests that its expression is constitutive and that it might play an important role in the pathogenesis of MM. PMID:12707028

  6. STAT3-Mediated Autophagy Dependence Identifies Subtypes of Breast Cancer where Autophagy Inhibition can be Efficacious

    PubMed Central

    Maycotte, Paola; Gearheart, Christy M.; Barnard, Rebecca; Aryal, Suraj; Mulcahy Levy, Jean M.; Fosmire, Susan P.; Hansen, Ryan J.; Morgan, Michael J.; Porter, Christopher C.; Gustafson, Daniel L.; Thorburn, Andrew

    2014-01-01

    Autophagy is a protein and organelle degradation pathway that is involved in diverse diseases including cancer. Recent evidence suggests that autophagy is a cell survival mechanism in tumor cells and that its inhibition especially in combination with other therapy could be beneficial but it remains unclear if all cancer cells behave the same way when autophagy is inhibited. We inhibited autophagy in a panel of breast cancer cell lines and found that some of them are dependent on autophagy for survival even in nutrient rich conditions without any additional stress while others need autophagy only when stressed. Survival under unstressed conditions is due to cell type specific autophagy regulation of STAT3 activity and this phenotype is enriched in triple negative cell lines. This autophagy-dependency affects response to therapy because autophagy inhibition reduced tumor growth in vivo in autophagy-dependent but not in autophagy-independent breast tumors while combination treatment with autophagy inhibitors and other agent was preferentially synergistic in autophagy-dependent cells. These results imply that autophagy-dependence represents a tumor cell specific characteristic where autophagy inhibition will be more effective. Moreover, our results suggest that autophagy inhibition might be a potential therapeutic strategy for triple negative breast cancers, which currently lack an effective targeted treatment. PMID:24590058

  7. Oleanane triterpenoid CDDO-Me induces apoptosis in multidrug resistant osteosarcoma cells through inhibition of Stat3 pathway

    PubMed Central

    2010-01-01

    Background The activation of signal transducer and activator of transcription 3 (Stat3) pathway correlates with tumor growth, survival, drug resistance and poor prognosis in osteosarcoma. To explore the potential therapeutic values of this pathway, we assessed both the expression and the activation of Stat3 pathway in several pairs of multidrug resistant (MDR) osteosarcoma cell lines, and tissues. To explore the potential therapeutic values of this pathway, we analyzed the ability of the synthetic oleanane triterpenoid, C-28 methyl ester of 2-cyano-3,12-dioxoolen-1,9-dien-28-oic acid (CDDO-Me), to inhibit Stat3 expression and activation as well as its effects on doxorubicin sensitivity in osteosarcoma cells. Methods Expression of Stat3, phosphorylated Stat3 (pStat3) and Stat3 targeted proteins, including Bcl-XL, Survivin and MCL-1 were determined in drug sensitive and MDR osteosarcoma cell lines and tissues by Western blot analysis. The effect of CDDO-Me on osteosarcoma cell growth was evaluated by MTT and apoptosis by PARP cleavage assay and caspase-3/7 activity. Results Stat3 pathway was activated in osteosarcoma tissues and in MDR cell lines. CDDO-Me inhibited growth and induced apoptosis in osteosarcoma cell lines. Treatment with CDDO-Me significantly decreased the level of nuclear translocation and phosphorylation of Stat3. The inhibition of Stat3 pathway correlated with the suppression of the anti-apoptotic Stat3 targeted genes Bcl-XL, survivin, and MCL-1. Furthermore, CDDO-Me increased the cytotoxic effects of doxorubicin in the MDR osteosarcoma cell lines. Conclusions Stat3 pathway is overexpressed in MDR osteosarcoma cells. CDDO-Me significantly inhibited Stat3 phosphorylation, Stat3 nuclear translocation and induced apoptosis in osteosarcoma. This study provides the framework for the clinical evaluation of CDDO-Me, either as monotherapy or perhaps even more effectively in combination with doxorubicin to treat osteosarcoma and overcome drug resistance. PMID:20459702

  8. Role of STAT3 in Angiotensin II-Induced Hypertension and Cardiac Remodeling Revealed by Mice Lacking STAT3 Serine 727 Phosphorylation

    PubMed Central

    Zouein, Fouad A.; Zgheib, Carlos; Hamza, Shereen; Fuseler, John W.; Hall, John E.; Soljancic, Andrea; Lopez-Ruiz, Arnaldo; Kurdi, Mazen; Booz, George W.

    2013-01-01

    STAT3 is involved in protection of the heart provided by ischemic preconditioning. However, the role of this transcription factor in the heart in chronic stresses such as hypertension has not been defined. We assessed whether STAT3 is important in hypertension-induced cardiac remodeling using mice with reduced STAT3 activity due to a S727A mutation (SA/SA). Wild type (WT) and SA/SA mice received angiotensin (ANG) II or saline for 17 days. ANG II increased mean arterial and systolic pressure in SA/SA and WT mice, but cardiac levels of cytokines associated with heart failure were increased less in SA/SA mice. Unlike WT mice, hearts of SA/SA mice showed signs of developing systolic dysfunction as evidenced by reduction in ejection fraction and fractional shortening. In the left ventricle of both WT and SA/SA mice, ANG II induced fibrosis. However, fibrosis in SA/SA mice appeared more extensive and was associated with loss of myocytes. Cardiac hypertrophy as indexed by heart to body weight ratio and left ventricular anterior wall dimension during diastole was greater in WT mice. In WT+ANG II mice there was an increase in the mass of individual myofibrils. In contrast, cardiac myocytes of SA/SA+ANG II mice showed a loss in myofibrils and myofibrillar mass density was decreased during ANG II infusion. Our findings reveal that STAT3 transcriptional activity is important for normal cardiac myocyte myofibril morphology. Loss of STAT3 may impair cardiac function in the hypertensive heart due to defective myofibrillar structure and remodeling that may lead to heart failure. PMID:23364341

  9. STAT3-dependent VEGF production from keratinocytes abrogates dendritic cell activation and migration by arsenic: a plausible regional mechanism of immunosuppression in arsenical cancers.

    PubMed

    Hong, Chien-Hui; Lee, Chih-Hung; Chen, Gwo-Shing; Chang, Kee-Lung; Yu, Hsin-Su

    2015-02-01

    Arsenic remains an important environmental hazard that causes several human cancers. Arsenic-induced Bowen's disease (As-BD), a skin carcinoma in situ, is the most common arsenical cancer. While great strides have been made in our understanding of arsenic carcinogenesis, how host immunity contributes to this process remains unknown. Patients with As-BD have an impaired contact hypersensitivity response. Although impaired T cell activation has been well-documented in arsenical cancers, how dendritic cell (DC), the key cell regulating innate immunity, regulates the immune response in arsenical cancers remains unclear. Using myeloid derived DC (MDDC) from patients with As-BD and normal controls as well as bone marrow derived DC (BMDC) from mice fed with or without arsenic, we measured the migration of DC. As-BD patients showed an impaired CCL21-mediated MDDC migration in vitro. Arsenic-fed mice had defective DC migration toward popliteal lymph nodes when injected with allogenic BMDCs via foot pad. Using skin from As-BD and normal controls, we found an increased expression of STAT3, a transcriptional factor contributing to impaired DC activation. Arsenic induced STAT3 activation and the production of VEGF in keratinocytes. The increase in VEGF was blocked by inhibiting STAT3 with RNA interference or pharmaceutically with JSI-124. While VEGF by itself minimally induced the expression of CD86 and MHC-II in MDDC, arsenic induced-MDDC activation was abolished by VEGF pretreatment. We concluded that the STAT3-VEGF axis in keratinocytes inhibits DC migration in the microenvironment of As-BD, indicating that cellular interactions play an important role in regulating the disease course of arsenical cancers. PMID:25559853

  10. NgR1 Expressed in P19 Embryonal Carcinoma Cells Differentiated by Retinoic Acid Can Activate STAT3.

    PubMed

    Lee, Su In; Yun, Jieun; Baek, Ji-Young; Jeong, Yun-Ji; Kim, Jin-Ah; Kang, Jong Soon; Park, Sun Hong; Kim, Sang Kyum; Park, Song-Kyu

    2015-03-01

    NgR1, a Nogo receptor, is involved in inhibition of neurite outgrowth and axonal regeneration and regulation of synaptic plasticity. P19 embryonal carcinoma cells were induced to differentiate into neuron-like cells using all trans-retinoic acid and the presence and/or function of cellular molecules, such as NgR1, NMDA receptors and STAT3, were examined. Neuronally differentiated P19 cells expressed the mRNA and protein of NgR1, which could stimulate the phosphorylation of STAT3 when activated by Nogo-P4 peptide, an active segment of Nogo-66. During the whole period of differentiation, mRNAs of all of the NMDA receptor subtypes tested (NR1, NR2A-2D) were consistently expressed, which meant that neuronally differentiated P19 cells maintained some characteristics of neurons, especially central nervous system neurons. Our results suggests that neuronally differentiated P19 cells expressing NgR1 may be an efficient and convenient in vitro model for studying the molecular mechanism of cellular events that involve NgR1 and its binding partners, and for screening compounds that activate or inhibit NgR1. PMID:25729271

  11. NgR1 Expressed in P19 Embryonal Carcinoma Cells Differentiated by Retinoic Acid Can Activate STAT3

    PubMed Central

    Lee, Su In; Yun, Jieun; Baek, Ji-Young; Jeong, Yun-Ji; Kim, Jin-Ah; Kang, Jong Soon; Park, Sun Hong; Kim, Sang Kyum

    2015-01-01

    NgR1, a Nogo receptor, is involved in inhibition of neurite outgrowth and axonal regeneration and regulation of synaptic plasticity. P19 embryonal carcinoma cells were induced to differentiate into neuron-like cells using all trans-retinoic acid and the presence and/or function of cellular molecules, such as NgR1, NMDA receptors and STAT3, were examined. Neuronally differentiated P19 cells expressed the mRNA and protein of NgR1, which could stimulate the phosphorylation of STAT3 when activated by Nogo-P4 peptide, an active segment of Nogo-66. During the whole period of differentiation, mRNAs of all of the NMDA receptor subtypes tested (NR1, NR2A-2D) were consistently expressed, which meant that neuronally differentiated P19 cells maintained some characteristics of neurons, especially central nervous system neurons. Our results suggests that neuronally differentiated P19 cells expressing NgR1 may be an efficient and convenient in vitro model for studying the molecular mechanism of cellular events that involve NgR1 and its binding partners, and for screening compounds that activate or inhibit NgR1. PMID:25729271

  12. Antitumor progression potential of morusin suppressing STAT3 and NF?B in human hepatoma SK-Hep1 cells.

    PubMed

    Lin, Wea-Lung; Lai, Deng-Yu; Lee, Yean-Jang; Chen, Nai-Fang; Tseng, Tsui-Hwa

    2015-01-22

    Morusin is a prenylated flavonoid that has been isolated from the root bark of the mulberry tree (Morus species, Moraceae), a Chinese traditional medicine. It has been synthesized by our laboratory from commercially available phloroglucinol, and has demonstrated to possess antitumor effects of cell lines including A549, MCF-7, and MDA-MB-231. In this study, at non-cytotoxic concentrations, morusin altered invasive morphology and suppressed cell-matrix adhesion, cell motility and cell invasion in SK-Hep1 cells. Morusin also increased the expression of E-cadherin, an epithelial cell junction protein, decreased the expression of vimentin, a mesecnchymal marker, and ?2-, ?6-, ?1- integrin, which regulated cancer attachment and migration. In addition, morusin reduced the activity of matrix metalloproteinase-2 and 9 (MMP-2 and MMP-9), which were involved in extracellular matrix (ECM) degradation and promoting cancer cell invasion. Furthermore, morusin suppressed the signal transducer and activator of transcription 3 (STAT3) and nuclear factor-?B (NF?B) signaling pathways, which modulate the protein expression involved in the invasion process. Finally, morusin decreased the lung colonization of the SK-Hep1 cells in the nude mice. These results indicate morusin possesses antitumor progression potential through suppressing STAT3 and NF?B. PMID:25476160

  13. Polyunsaturated fatty acids promote the expansion of myeloid-derived suppressor cells by activating the JAK/STAT3 pathway.

    PubMed

    Yan, Dehong; Yang, Quan; Shi, Maohua; Zhong, Limei; Wu, Changyou; Meng, Tao; Yin, Huiyong; Zhou, Jie

    2013-11-01

    Polyunsaturated fatty acids (PUFAs) exert immunosuppressive effects that could prove beneficial in clinical therapies for certain autoimmune and inflammatory disorders. However, the mechanism of PUFA-mediated immunosuppression is far from understood. Here, we provide evidence that PUFAs enhance the accumulation of myeloid-derived suppressor cells (MDSCs), a negative immune regulator. PUFA-induced MDSCs have a more potent suppressive effect on T-cell responses than do control MDSCs. These observations were found both in cultured mouse bone marrow cells in vitro and in vivo in mice fed diets enriched in PUFAs. The enhanced suppressive activity of MDSCs by PUFAs administration was coupled with a dramatic induction of nicotinamide adenine dinucleo- tide phosphate oxidase subunit p47(phox) and was dependent on reactive oxygen species (ROS) production. Mechanistic studies revealed that PUFAs mediate its effects through JAK-STAT3 signaling. Inhibition of STAT3 phosphorylation by JAK inhibitor JSI-124 almost completely abrogated the effects of PUFAs on MDSCs. Moreover, the effects of PUFAs on MDSCs and the underlying mechanisms were confirmed in tumor-bearing mice. In summary, this study sheds new light on the immune modulatory role of PUFAs, and demonstrates that MDSCs expansion may mediate the effects of PUFAs on the immune system. PMID:23897117

  14. 2'-hydroxyflavanone inhibits prostate tumor growth through inactivation of AKT/STAT3 signaling and induction of cell apoptosis.

    PubMed

    Wu, Kaijie; Ning, Zhongyun; Zhou, Jiancheng; Wang, Bin; Fan, Jinhai; Zhu, Jianning; Gao, Yang; Wang, Xinyang; Hsieh, Jer-Tsong; He, Dalin

    2014-07-01

    Although there have been advances in therapeutic regimes for metastatic castration-resistant prostate cancer (CRPC), these recent developments have not led to improved cure rates. Thus, more novel agents to prolong patient survival are desired. 2'-Hydroxyflavanone (2HF), a nontoxic natural flavonoid, has been shown to exhibit pleiotropic anticancer effects in many cancer types, including prostate cancer (PCa). However, the therapeutic effects of 2HF on tumor growth and its potential mechanisms in CRPC have not been completely elucidated. In the present study, utilizing three different metastatic and androgen-independent PCa cell models (PC-3, DU145 and C4-2), we found that 2HF treatment not only resulted in inhibition of cell proliferation and colony formation in vitro, but also delayed subcutaneous tumor growth in vivo. Mechanistically, besides its known inhibitory effects on aldo?keto reductase activity and de novo androgen synthesis, 2HF also markedly suppressed AKT phosphorylation, signal transducer and activator of transcription-3 (STAT3) phosphorylation and transactivation subsequently regulating the expression of members of the BCL-2 family (i.e., Mcl-1, Bcl-2 and Bax) and modulating caspase-mediated cell apoptosis. Overall, this study revealed a novel mechanism for 2HF targeting metastatic CRPC, in which inactivation of AKT/STAT3 signaling led to cell apoptosis and growth inhibition. PMID:24859932

  15. Stat3: linking inflammation to epithelial cancer - more than a "gut" feeling?

    PubMed Central

    2010-01-01

    Inflammation is an important environmental factor that promotes tumourigenesis and the progression of established cancerous lesions, and recent studies have started to dissect the mechanisms linking the two pathologies. These inflammatory and infectious conditions trigger immune and stromal cell release of soluble mediators which facilitate survival and proliferation of tumour cells in a paracrine manner. In addition, (epi-)genetic mutations affecting oncogenes, tumour-suppressor genes, chromosomal rearrangements and amplifications trigger the release of inflammatory mediators within the tumour microenvironment to promote neoplastic growth in an autocrine manner. These two pathways converge in tumour cells and result in activation of the latent signal transducer and activator of transcription 3 (Stat3) which mediates a transcriptional response favouring survival, proliferation and angiogenesis. The abundance of cytokines that activate Stat3 within the tumour microenvironment, which comprises of members of the interleukin (IL) IL6, IL10 and IL17/23 families, underpins a signaling network that simultaneously promotes the growth of neoplastic epithelium, fuels inflammation and suppresses the host's anti-tumour immune response. Accordingly, aberrant and persistent Stat3 activation is a frequent observation in human cancers of epithelial origin and is often associated with poor outcome. Here we summarize insights gained from mice harbouring mutations in components of the Stat3 signaling cascade and in particular of gp130, the shared receptor for the IL6 family of cytokines. We focus on the various feed-back and feed-forward loops in which Stat3 provides the signaling node in cells of the tumour and its microenvironment thereby functionally linking excessive inflammation to neoplastic growth. Although these observations are particularly pertinent to gastrointestinal tumours, we suggest that the tumour's addiction to persistent Stat3 activation is likely to also impact on other epithelial cell-derived cancers. These insights provide clues to the judicious interference of the gp130/Stat3 signaling cascade in therapeutically targeting cancer. PMID:20478049

  16. The study of c-Src kinase and pStat3 protein expression in retinoblastoma.

    PubMed

    Mohan, Adithi; Mallikarjuna, Kandalam; Venkatesan, Nalini; Abhyankar, Dhiraj; Parikh, Purvish M; Krishnakumar, Subramanian

    2006-10-01

    We examine the immunoreactivity of the non-receptor tyrosine kinase, c-Src kinase and its downstream molecule, signal transducer and activator of transcription 3 (pStat3) in retinoblastoma (RB), and correlation with invasiveness and differentiation. Tumor samples from 40 patients with RB were available for the study. There were 18 tumors in group 1 (non-invasive) and 22 tumors in group 2 (invasive). The immunoreactivity of c-Src kinase and pStat3 was compared in the two groups of tumors. Group 1 (non-invasive) RB showed intermediate c-Src kinase immunoreactivity (Allred score 4-5) in 14/18 tumors and low immunoreactivity (Allred score 2-3) in 4/18 tumors. pStat3 was intermediate (Allred score 4-5) in 6/18 tumors and negative (Allred score 0) in 12/18 tumors. Group 2 (invasive) RB showed high c-Src kinase immunoreactivity (Allred score 6-8) in 22/22 tumors and high pStat3 (Allred score 6-8) in 19/22 tumors. The expression of c-Src kinase (P<0.001) and pStat3 (P<0.001) was significantly higher in group 2 RB. Src kinase expression (P<0.05) and pStat3 expression (P<0.05) was higher in the poorly differentiated tumors compared to moderately- and well-differentiated tumors. The increased expression of c-Src kinase and pStat3 expression could play a role in the invasiveness of group 2 tumors. Further characterization of the pathways involved in the pathogenesis of RB will shed light on fundamental mechanisms of tumorigenesis. PMID:16716300

  17. The Status of STAT3 and STAT5 in Human Breast Atypical Ductal Hyperplasia

    PubMed Central

    Shi, Aiping; Dong, Jie; Hilsenbeck, Susan; Bi, Lirong; Zhang, Hong; Li, Yi

    2015-01-01

    Signal Transducer and Activation of Transcription factors (STAT3 and STAT5) play important roles in breast epithelial cell differentiation, proliferation, and apoptosis. They have been investigated extensively in established breast cancer, but their activation status in precancerous lesions has not been reported. Formalin-fixed, paraffin-embedded archival tissues from 59 cases of atypical ductal hyperplasia (ADH) and 31 cases of normal human breast tissue as well as 21 cases of usual ductal hyperplasias (UDH) were obtained from the First Hospital of Jilin University, China, and stained for pSTAT3 and pSTAT5 by immunohistochemistry. The median percentage of pSTAT5+ cells in ADH was 12%, not significantly deviant from that in normal breast. The median percentage of pSTAT3+ cells in ADH was 30%, significantly higher than that of normal breast. pSTAT3 and pSTAT5 were exclusive of each other—they were detected in different ADHs or in different cells within the same ADHs. In addition, both pSTAT3 and pSTAT5 were produced in similar percentages of cells in ADHs from cancer-free patients vs. ADHs that were adjacent to an invasive cancer. Our finding of a complementary expression pattern of pSTAT3 and pSTAT5 in ADH suggests that these two transcription factors may have feedback inhibitory effects on each other during early stages of breast cancer evolution, and that disruption of this inverse relationship may be important in the progression from early lesions to cancer, which exhibits positive association between pSTAT3 and pSTAT5. PMID:26146825

  18. Vaccinia Virus Induces Rapid Necrosis in Keratinocytes by a STAT3-Dependent Mechanism

    PubMed Central

    He, Yong; Fisher, Robert; Chowdhury, Soma; Sultana, Ishrat; Pereira, Claudia P.; Bray, Mike; Reed, Jennifer L.

    2014-01-01

    Rationale Humans with a dominant negative mutation in STAT3 are susceptible to severe skin infections, suggesting an essential role for STAT3 signaling in defense against cutaneous pathogens. Methods To focus on innate antiviral defenses in keratinocytes, we used a standard model of cutaneous infection of severe combined immunodeficient mice with the current smallpox vaccine, ACAM-2000. In parallel, early events post-infection with the smallpox vaccine ACAM-2000 were investigated in cultured keratinocytes of human and mouse origin. Results Mice treated topically with a STAT3 inhibitor (Stattic) developed larger vaccinia lesions with higher virus titers and died more rapidly than untreated controls. Cultured human and murine keratinocytes infected with ACAM-2000 underwent rapid necrosis, but when treated with Stattic or with inhibitors of RIP1 kinase or caspase-1, they survived longer, produced higher titers of virus, and showed reduced activation of type I interferon responses and inflammatory cytokines release. Treatment with inhibitors of RIP1 kinase and STAT3, but not caspase-1, also reduced the inflammatory response of keratinocytes to TLR ligands. Vaccinia growth properties in Vero cells, which are known to be defective in some antiviral responses, were unaffected by inhibition of RIP1K, caspase-1, or STAT3. Conclusions Our findings indicate that keratinocytes suppress the replication and spread of vaccinia virus by undergoing rapid programmed cell death, in a process requiring STAT3. These data offer a new framework for understanding susceptibility to skin infection in patients with STAT3 mutations. Interventions which promote prompt necroptosis/pyroptosis of infected keratinocytes may reduce risks associated with vaccination with live vaccinia virus. PMID:25419841

  19. Prevention of Trauma and Hemorrhagic Shock-Mediated Liver Apoptosis by Activation of Stat3?

    PubMed Central

    Moran, Ana; Akcan Arikan, Ayse; Mastrangelo, Mary-Ann A.; Wu, Yong; Yu, Bi; Poli, Valeria; Tweardy, David J.

    2008-01-01

    Trauma is a major cause of mortality in the United States. Death among those surviving the initial insult is caused by multiple organ failure (MOF) with the liver among the organs most frequently affected. We previously demonstrated in rodents that trauma complicated by hemorrhagic shock (trauma/HS) results in liver injury that can be prevented by IL-6 administration at the start of resuscitation; however, the contribution of the severity of HS to the extent of liver injury, whether or not resuscitation is required and the mechanism for the IL-6 protective effect have not been reported. In the experiments reported here, we demonstrated that the extent of liver apoptosis induced by trauma/HS depends on the duration of hypotension and requires resuscitation. We established that IL-6 administration at the start of resuscitation is capable of completely reversing liver apoptosis and is associated with increased Stat3 activation. Microarray analysis of the livers showed that the main effect of IL-6 was to normalize the trauma/HS-induced apoptosis transcriptome. Pharmacological inhibition of Stat3 activity within the liver blocked the ability of IL-6 to prevent liver apoptosis and to normalize the trauma/HS- induced liver apoptosis transcriptome. Genetic deletion of a Stat3?, a naturally occurring, dominant-negative isoform of the Stat3, attenuated trauma/HS-induced liver apoptosis, confirming a role for Stat3, especially Stat3?, in preventing trauma/HS-mediated liver apoptosis. Thus, trauma/HS-induced liver apoptosis depends on the duration of hypotension and requires resuscitation. IL-6 administration at the start of resuscitation reverses HS-induced liver apoptosis, through activation of Stat3?, which normalizes the trauma/HS-induced liver apoptosis transcriptome. PMID:18997875

  20. Caveolin-1 upregulation mediates suppression of primary breast tumor growth and brain metastases by Stat3 inhibition

    PubMed Central

    Chiu, Wen-Tai; Lee, Hsueh-Te; Huang, Feng-Ju; Aldape, Kenneth D.; Yao, Jun; Steeg, Patricia S.; Chou, Cheng-Yang; Lu, Zhimin; Xie, Keping; Huang, Suyun

    2014-01-01

    Stat3 activation has been implicated as an important driver of brain metastasis in breast cancer, but the critical targets of Stat3 in this process are yet to be fully defined. In this study, we identified the lipid raft organizing protein Caveolin-1 (Cav-1) as a critical genetic target of Stat3 in this process. In human breast cancers, we found that activated Stat3 correlated with attenuation of Cav-1 in brain metastases relative to primary tumors. Cav-1 promoter activity and gene expression was increased by overexpressing an activated form of Stat3, but decreased by attenuation of Stat3 activity or expression. We identified putative Stat3-binding elements in the Cav-1 promoter and demonstrated a direct repression of Cav-1 transcription by Stat3. Reciprocally, we demonstrated that strategies to increase or decrease Cav-1 expression were sufficient to attenuate or promote breast cancer cell invasion. Further, increased expression of Cav-1 phenocopied the effects of Stat3 activation in blocking primary tumor growth and abrogating formation of brain metastases. Collectively, our findings provide clinical and mechanistic evidence that Cav-1 is a critical target for suppression by Stat3 in driving invasion and metastasis of breast cancer cells. PMID:21622714

  1. Feedback activation of STAT3 mediates trastuzumab resistance via upregulation of MUC1 and MUC4 expression.

    PubMed

    Li, Guangchao; Zhao, Likun; Li, Wei; Fan, Kexing; Qian, Weizhu; Hou, Sheng; Wang, Hao; Dai, Jianxin; Wei, Huafeng; Guo, Yajun

    2014-09-30

    Although HER2-targeting antibody trastuzumab confers a substantial benefit for patients with HER2-overexpressing breast and gastric cancer, overcoming trastuzumab resistance remains a large unmet need. In this study, we revealed a STAT3-centered positive feedback loop that mediates the resistance of trastuzumab. Mechanistically, chronic exposure of trastuzumab causes the upregulation of fibronection (FN), EGF and IL-6 in parental trastuzumab-sensitive breast and gastric cells and convergently leads to STAT3 hyperactivation. Activated STAT3 enhances the expression of FN, EGF and IL-6, thus constituting a positive feedback loop which amplifies and maintains the STAT3 signal; furthermore, hyperactivated STAT3 signal promotes the expression of MUC1 and MUC4, consequently mediating trastuzumab resistance via maintenance of persistent HER2 activation and masking of trastuzumab binding to HER2 respectively. Genetic or pharmacological inhibition of STAT3 disrupted STAT3-dependent positive feedback loop and recovered the trastuzumab sensitivity partially due to increased apoptosis induction. Combined trastuzumab with STAT3 inhibition synergistically suppressed the growth of the trastuzumab-resistant tumor xenografts in vivo. Taken together, our results suggest that feedback activation of STAT3 constitutes a key node mediating trastuzumab resistance. Combinatorial targeting on both HER2 and STAT3 may enhance the efficacy of trastuzumab or other HER2-targeting agents in HER2-positive breast and gastric cancer. PMID:25327561

  2. Humanized Lewis-Y specific antibody based delivery of STAT3 siRNA

    PubMed Central

    Ma, Yuelong; Kowolik, Claudia M.; Swiderski, Piotr M.; Kortylewski, Marcin; Yu, Hua; Horne, David A.; Jove, Richard; Caballero, Otavia L.; Simpson, Andrew J.G.; Lee, Fook-Thean; Pillay, Vinochani; Scott, Andrew M.

    2013-01-01

    The clinical application of siRNA is limited largely by the lack of efficient, cell-specific delivery systems. Antibodies are attractive delivery vehicles for targeted therapy due to their high specificity. In this study we describe the use of a humanized monoclonal antibody (mAb), hu3S193, against Lewis-Y (Ley), as a delivery vehicle for STAT3 siRNA. This mAb is rapidly internalized into Ley expressing cancer cells via antigen recognition, and when coupled to STAT3 siRNA, a potentially powerful molecularly targeted delivery agent is created. Selective silencing of STAT3 is associated with tumor suppression. Two hu3S193 based siRNA delivery systems using STAT3 siRNA as a prototype were developed and tested in Ley-positive cancer cells: (a) a covalent construct based on a reductive disulfide linker that is expected to undergo cleavage within cells and (b) a non-covalent construct based on (D-Arginine)9 (9r) modified hu3S193. Ley-specific binding and internalization of both the covalent and non-covalent constructs were confirmed by flow cytometry and confocal microscopy. Both the covalent and the non-covalent system led to efficient STAT3 silencing in Ley-positive cancer cells (A431), but not in Ley-negative cancer cells (MDA-MB-435). The covalent construct, however, required co-treatment with reagents such as chloroquine or 9r that facilitate the escape of the siRNA from endosomes to achieve significant gene silencing. The 9r modified non-covalent construct, induced ~70% STAT3 knockdown at sub-micromolar siRNA concentrations when used at an optimal vehicle-to-siRNA ratio of 5:1. The STAT3 knockdown also led to ~50% inhibition of cell proliferation of Ley-positive cells. Non-covalent linked STAT3 siRNA-hu3S193 has great promise for targeted knockdown of STAT3 in tumor cells. PMID:21766840

  3. Characterization of molecular recognition of STAT3 SH2 domain inhibitors through molecular simulation.

    PubMed

    Park, In-Hee; Li, Chenglong

    2011-01-01

    Signal transducer and activator of transcription 3 (STAT3) is an anti-cancer target protein due to its over-activation in tumor cells. The Tyr705-phosphorylated (pTyr) STAT3 binds to the pTyr-recognition site of its Src Homology 2 (SH2) domain of another STAT3 monomer to form a homo-dimer, which then causes cellular anti-apoptosis, proliferation, and tumor invasion. Recently, many STAT3 SH2 dimerization inhibitors have been discovered via both computational and experimental methods. To systematically assess their binding affinities and specificities, for eight representative inhibitors, we utilized molecular docking, molecular dynamics simulation, and ensuing energetic analysis to compare their binding characteristics. The inhibitors' binding free energies were calculated via MMPB(GB)SA, and the STAT3 SH2 binding "hot spots" were evaluated through binding energy decomposition and hydrogen bond (H-bond) distribution analysis. Several conclusions can be drawn: (1) the overall enthalpy-entropy compensation paradigm is preserved for the STAT3 SH2/ligand binding thermodynamics; (2) at one end of the binding spectrum, two compounds bind to SH2 due to their minimum entropic penalties that result from their relative rigidities and increased dynamics of SH2 upon their binding; at the other end of the binding spectrum, one compound shows a typical weak binder behavior due to its loose binding in the SH2's strongest enthalpy-contributing binding subsite; (3) hydrogen bonding seems a strong indicator to evaluate the SH2/ligand binding potency, which echoes a finding that CH/? non-classical H-bond is responsible for some pTyr peptides binding to their corresponding SH2 domains; (4) STAT3 SH2 domain possesses three binding "hot spots": pTyr705-binding pocket with polar residues and contributing the largest binding enthalpy (two-thirds); Leu706 subsite which is the most dynamic and hardest to target; a hydrophobic side pocket which is unique to STAT3 and very targetable, which may offer unique opportunity to design STAT3-specific inhibitors, particularly with fragment-based approach. PMID:21360612

  4. G-CSF Promotes Neuroblastoma Tumorigenicity and Metastasis via STAT3-Dependent Cancer Stem Cell Activation.

    PubMed

    Agarwal, Saurabh; Lakoma, Anna; Chen, Zaowen; Hicks, John; Metelitsa, Leonid S; Kim, Eugene S; Shohet, Jason M

    2015-06-15

    Increasing evidence suggests that inflammatory cytokines play a critical role in tumor initiation and progression. A cancer stem cell (CSC)-like subpopulation in neuroblastoma is known to be marked by expression of the G-CSF receptor (G-CSFR). Here, we report on the mechanistic contributions of the G-CSFR in neuroblastoma CSCs. Specifically, we demonstrate that the receptor ligand G-CSF selectively activates STAT3 within neuroblastoma CSC subpopulations, promoting their expansion in vitro and in vivo. Exogenous G-CSF enhances tumor growth and metastasis in human xenograft and murine neuroblastoma tumor models. In response to G-CSF, STAT3 acts in a feed-forward loop to transcriptionally activate the G-CSFR and sustain neuroblastoma CSCs. Blockade of this G-CSF-STAT3 signaling loop with either anti-G-CSF antibody or STAT3 inhibitor depleted the CSC subpopulation within tumors, driving correlated tumor growth inhibition, decreased metastasis, and increased chemosensitivity. Taken together, our results define G-CSF as a CSC-activating factor in neuroblastoma, suggest a comprehensive reevaluation of the clinical use of G-CSF in these patients to support white blood cell counts, and suggest that direct targeting of the G-CSF-STAT3 signaling represents a novel therapeutic approach for neuroblastoma. Cancer Res; 75(12); 2566-79. ©2015 AACR. PMID:25908586

  5. Reinforcement of STAT3 activity reprogrammes human embryonic stem cells to naive-like pluripotency

    PubMed Central

    Chen, Hongwei; Aksoy, Irène; Gonnot, Fabrice; Osteil, Pierre; Aubry, Maxime; Hamela, Claire; Rognard, Cloé; Hochard, Arnaud; Voisin, Sophie; Fontaine, Emeline; Mure, Magali; Afanassieff, Marielle; Cleroux, Elouan; Guibert, Sylvain; Chen, Jiaxuan; Vallot, Céline; Acloque, Hervé; Genthon, Clémence; Donnadieu, Cécile; De Vos, John; Sanlaville, Damien; Guérin, Jean- François; Weber, Michael; Stanton, Lawrence W; Rougeulle, Claire; Pain, Bertrand; Bourillot, Pierre-Yves; Savatier, Pierre

    2015-01-01

    Leukemia inhibitory factor (LIF)/STAT3 signalling is a hallmark of naive pluripotency in rodent pluripotent stem cells (PSCs), whereas fibroblast growth factor (FGF)-2 and activin/nodal signalling is required to sustain self-renewal of human PSCs in a condition referred to as the primed state. It is unknown why LIF/STAT3 signalling alone fails to sustain pluripotency in human PSCs. Here we show that the forced expression of the hormone-dependent STAT3-ER (ER, ligand-binding domain of the human oestrogen receptor) in combination with 2i/LIF and tamoxifen allows human PSCs to escape from the primed state and enter a state characterized by the activation of STAT3 target genes and long-term self-renewal in FGF2- and feeder-free conditions. These cells acquire growth properties, a gene expression profile and an epigenetic landscape closer to those described in mouse naive PSCs. Together, these results show that temporarily increasing STAT3 activity is sufficient to reprogramme human PSCs to naive-like pluripotent cells. PMID:25968054

  6. STAT3 Induction of MiR-146b Forms a Feedback Loop to Inhibit the NF-?B to IL-6 Signaling Axis and STAT3-Driven Cancer Phenotypes

    PubMed Central

    Xiang, Michael; Birkbak, Nicolai J.; Vafaizadeh, Vida; Walker, Sarah R.; Yeh, Jennifer E.; Liu, Suhu; Kroll, Yasmin; Boldin, Mark; Taganov, Konstantin; Groner, Bernd; Richardson, Andrea L.; Frank, David A.

    2014-01-01

    Interleukin-6 (IL-6)-mediated activation of signal transducer and activator of transcription 3 (STAT3) is a mechanism by which chronic inflammation can contribute to cancer and is a common oncogenic event. We discovered a pathway the loss of which is associated with persistent STAT3 activation in human cancer. We found that the gene encoding the tumor suppressor microRNA miR-146b is a direct STAT3 target gene and its expression was increased in normal breast epithelial cells but decreased in tumor cells. Methylation of the miR-146b promoter, which inhibited STAT3-mediated induction of expression, was increased in primary breast cancers. Moreover, we found that miR-146b inhibited nuclear factor ?B (NF-?B)-dependent production of IL-6, subsequent STAT3 activation, and IL-6/STAT3-driven migration and invasion in breast cancer cells, thereby establishing a negative feedback loop. In addition, higher expression of miR-146b was positively correlated with patient survival in breast cancer subtypes with increased IL6 expression and STAT3 phosphorylation. Our results identify an epigenetic mechanism of crosstalk between STAT3 and NF-?B relevant to constitutive STAT3 activation in malignancy and the role of inflammation in oncogenesis. PMID:24473196

  7. Stat3 Upregulates Leucine-Rich Repeat-Containing G Protein-Coupled Receptor 4 Expression in Osteosarcoma Cells

    PubMed Central

    Liu, Jia; Wei, Wei; Guo, Chang-An; Han, Ning; Pan, Jian-feng; Fei, Teng; Yan, Zuo-qin

    2013-01-01

    The activation of signal transducer and activator of transcription 3 (Stat3) signaling is the common hallmark in various human cancers including osteosarcoma. In the present study, according to PCR-based microarrays using cDNA prepared from interleukin-6 (IL-6) treated osteosarcoma cells, we found that leucine-rich repeat-containing G protein-coupled receptor 4 (LGR4) was a transcriptional target of Stat3. Overexpression of Stat3 promoted LGR4 expression, while its deficiency using small interfering RNA (siRNA) reduced LGR4 expression. Furthermore, we identified a Stat3 binding motif located at ?556 to ?549?bp in the LGR4 promoter that is able to interact with Stat3. Thus, our results suggest a previously unknown Stat3-LGR4 molecular network, which may control osteosarcoma development and progression. PMID:24455684

  8. Local axonal function of STAT3 rescues axon degeneration in the pmn model of motoneuron disease

    PubMed Central

    Selvaraj, Bhuvaneish Thangaraj; Frank, Nicolas; Bender, Florian L.P.; Asan, Esther

    2012-01-01

    Axonal maintenance, plasticity, and regeneration are influenced by signals from neighboring cells, in particular Schwann cells of the peripheral nervous system. Schwann cells produce neurotrophic factors, but the mechanisms by which ciliary neurotrophic factor (CNTF) and other neurotrophic molecules modify the axonal cytoskeleton are not well understood. In this paper, we show that activated signal transducer and activator of transcription-3 (STAT3), an intracellular mediator of the effects of CNTF and other neurotrophic cytokines, acts locally in axons of motoneurons to modify the tubulin cytoskeleton. Specifically, we show that activated STAT3 interacted with stathmin and inhibited its microtubule-destabilizing activity. Thus, ectopic CNTF-mediated activation of STAT3 restored axon elongation and maintenance in motoneurons from progressive motor neuronopathy mutant mice, a mouse model of motoneuron disease. This mechanism could also be relevant for other neurodegenerative diseases and provide a target for new therapies for axonal degeneration. PMID:23109669

  9. Dovitinib induces apoptosis and overcomes sorafenib resistance in hepatocellular carcinoma through SHP-1-mediated inhibition of STAT3.

    PubMed

    Tai, Wei-Tien; Cheng, Ann-Lii; Shiau, Chung-Wai; Liu, Chun-Yu; Ko, Ching-Huai; Lin, Mai-Wei; Chen, Pei-Jer; Chen, Kuen-Feng

    2012-02-01

    The multiple kinase inhibitor dovitinib is currently under clinical investigation for hepatocellular carcinoma (HCC). Here, we investigated the mechanistic basis for the effects of dovitinib in HCCs. Dovitinib showed significant antitumor activity in HCC cell lines PLC5, Hep3B, Sk-Hep1, and Huh-7. Dovitinib downregulated phospho-STAT3 (p-STAT3) at tyrosine 705 and subsequently reduced the levels of expression of STAT3-related proteins Mcl-1, survivin, and cyclin D1 in a time-dependent manner. Ectopic expression of STAT3 abolished the apoptotic effect of dovitinib, indicating that STAT3 is indispensable in mediating the effect of dovitinib in HCC. SHP-1 inhibitor reversed downregulation of p-STAT3 and apoptosis induced by dovitinib, and silencing of SHP-1 by RNA interference abolished the effects of dovitinib on p-STAT3, indicating that SHP-1, a protein tyrosine phosphatase, mediates the effects of dovitinib. Notably, dovitinib increased SHP-1 activity in HCC cells. Incubation of dovitinib with pure SHP-1 protein enhanced its phosphatase activity, indicating that dovitinib upregulates the activity of SHP-1 via direct interactions. In addition, dovitinib induced apoptosis in two sorafenib-resistant cell lines through inhibition of STAT3, and sorafenib-resistant cells showed significant activation of STAT3, suggesting that targeting STAT3 may be a useful approach to overcome drug resistance in HCC. Finally, in vivo, dovitinib significantly suppressed growth of both Huh-7 and PLC5 xenograft tumors and downregulated p-STAT3 by increasing SHP-1 activity. In conclusion, dovitinib induces significant apoptosis in HCC cells and sorafenib-resistant cells via SHP-1-mediated inhibition of STAT3. PMID:22180308

  10. Analysis of Stat3 (signal transducer and activator of transcription 3) dimerization by fluorescence resonance energy transfer in living cells.

    PubMed Central

    Kretzschmar, Antje K; Dinger, Michaela C; Henze, Christian; Brocke-Heidrich, Katja; Horn, Friedemann

    2004-01-01

    Signal transducer and activator of transcription 3 (Stat3) dimerization is commonly thought to be triggered by its tyrosine phosphorylation in response to interleukin-6 (IL-6) or other cytokines. Accumulating evidence from in vitro studies, however, suggests that cytoplasmic Stat3 may be associated with high-molecular-mass protein complexes and/or dimerize prior to its activation. To directly study Stat3 dimerization and subcellular localization upon cytokine stimulation, we used live-cell fluorescence spectroscopy and imaging microscopy combined with fluorescence resonance energy transfer (FRET). Stat3 fusion proteins with spectral variants of green fluorescent protein (GFP), cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP) were constructed and expressed in human hepatoma cells (HepG2) and human embryonic kidney cells (HEK-293). Like wild-type Stat3, the fusion proteins redistributed from a preferentially cytoplasmic to nuclear localization upon IL-6 stimulation and supported IL-6-dependent target gene expression. FRET studies in cells co-expressing Stat3-CFP and Stat3-YFP demonstrated that Stat3 dimers exist in the absence of tyrosine phosphorylation. IL-6 induced a 2-fold increase of this basal FRET signal, indicating that tyrosine phosphorylation either increases the dimer/monomer ratio of Stat3 or induces a conformational change of the dimer yielding a higher FRET efficiency. Studies using a mutated Stat3 with a non-functional src-homology 2 (SH2) domain showed that the SH2 domain is essential for dimer formation of phosphorylated as well as non-phosphorylated Stat3. Furthermore, our data show that visualization of normalized FRET signals allow insights into the spatiotemporal dynamics of Stat3 signal transduction. PMID:12974672

  11. STAT3 and SOCS3 Expression Patterns During Murine Placenta Development

    PubMed Central

    San Martin, S.; Fitzgerald, J.S.; Weber, M.; Párraga, M.; Sáez, T.; Zorn, T.M.; Markert, U.R.

    2013-01-01

    Signal transducers and activators of transcription 3 (STAT3) has been identified as an important signal transducer in the invasive phenotype of the trophoblasts cells in in vitro studies. However, the in situ distribution and patterns of expression of this molecule in trophoblast cells during the development of the placenta are still under-elucidated. Mice uteri of gestational ages between 7 and 14 days of pregnancy (dop) were fixed in methacarn and processed with immunoperoxidase techniques for detection of STAT3 and its phosphorylation at serine (p-ser727) residues, as well as the suppressor of cytokine signaling 3 (SOCS3) expression. STAT3 was observed at 7 through 9 dop in both the antimesometrial and mesometrial deciduas, while continued immunoreactivity between 10 and 13 dop was seen only in the mesometrial decidua. In the placenta, STAT3 was detected in the cytotrophoblast cells of labyrinth and giant trophoblast cells between 10 and 14 dop. Immunoreactivity for STAT3 was also seen in trophoblast cells surrounding the maternal blood vessels. On days 10 and 11 of pregnancy, p-ser727 was detectable in the mesometrial decidua and in giant trophoblasts, while during 12-14 dop in the spongiotrophoblast region. In addition, SOCS3 was immunodetected in maternal and placental tissues, principally in the giant trophoblast cells during the whole period of the study. The present in situ study shows the distribution of STAT3, its serine activation and SOCS3 in different maternal and fetal compartments during murine placental development, thus further supporting the idea that they play a role during physiological placentation in mice. PMID:23807298

  12. SOCS3 promotes inflammation and apoptosis via inhibiting JAK2/STAT3 signaling pathway in 3T3-L1 adipocyte.

    PubMed

    Liu, Zhenjiang; Gan, Lu; Zhou, Zhongjie; Jin, Wei; Sun, Chao

    2015-08-01

    The suppressor of cytokine signaling 3 (SOCS3) is an established negative feedback regulation transcription factor associated with leptin, tumor necrosis factor-? (TNF-?), interferon-? (IFN-?) and growth hormone (GH). However, the regulatory mechanism of SOCS3 on inflammation and apoptosis of adipocyte is still not clear. In this study, we found an increased expression of adipocyte inflammatory cytokines TNF-? and IL-6 due to leptin treatment. Meanwhile Caspase3, a key executioner of apoptosis, was also elevated in this process. In addition, we observed that SOCS3 could promote inflammation whereas SOCS3 interference reversed this effect in LPS-induced adipocytes inflammatory model. Moreover, the expression of apoptosis-associated genes Bax, cleaved-Caspase9 and cleaved-Caspase3 were elevated along with decreased Bcl-2 expression as detected with Western blot and ELISA assay. The phosphorylation level of JAK2/STAT3 signal was inhibited by SOCS3 along with the elevated expression of IL-6, TNF-? and Caspase3. We also demonstrated that stable knockdown of SOCS3 along with SD1008, a specific inhibitor of JAK2/STAT3 signaling pathway, could significantly inhibit inflammation and apoptosis of adipocyte. Altogether, these results inferred that SOCS3 promotes adipocyte apoptosis by both aggravating inflammation and inhibiting the activity of JAK2/STAT3 signaling pathway. PMID:25720636

  13. Cytokine response is determined by duration of receptor and signal transducers and activators of transcription 3 (STAT3) activation.

    PubMed

    Braun, David A; Fribourg, Miguel; Sealfon, Stuart C

    2013-02-01

    Paradoxically, the pro-inflammatory cytokine IL-6 and the anti-inflammatory cytokine IL-10 both activate STAT3, yet generate nearly opposing cellular responses. Here, we show that the temporal pattern of STAT3 activation codes for the specific cytokine response. A computational model of IL-6 and IL-10 signaling predicted that IL-6 stimulation results in transient activation of STAT3, with a rapid decline in phosphorylation and nuclear localization. In contrast, simulated IL-10 signaling resulted in sustained STAT3 activation. The predicted STAT3 patterns produced by each cytokine were confirmed experimentally in human dendritic cells. Time course microarray studies further showed that the dynamic genome-wide transcriptional responses were nearly identical at early time points following stimulation (when STAT3 is active in response to both IL-6 and IL-10) but divergent at later times (when STAT3 is active only in response to IL-10). Truncating STAT3 activation after IL-10 stimulation caused IL-10 to elicit an IL-6-like transcriptional and secretory response. That the duration of IL-10 receptor and STAT3 activation can direct distinct responses reveals a complex cellular information-coding mechanism that may be relevant to improving the prediction of the effects of drug candidates using this mechanism. PMID:23166328

  14. Loss of STAT3 in mouse embryonic fibroblasts reveals its Janus-like actions on mitochondrial function and cell viability.

    PubMed

    Zouein, Fouad A; Duhé, Roy J; Arany, Istvan; Shirey, Kristin; Hosler, Jonathan P; Liu, Huiling; Saad, Iman; Kurdi, Mazen; Booz, George W

    2014-03-01

    STAT3 has been implicated in mitochondrial function; however, the physiological relevance of this action is not established. Here we studied the importance of STAT3 to the cellular response to stimuli, TNF? and serum deprivation, which increase mitochondrial reactive oxygen species (ROS) formation. Experiments were performed using wild type (WT) and STAT3 knockout (KO) mouse embryonic fibroblasts (MEF). Both WT and STAT3 KO MEF expressed similar levels of tumor necrosis factor receptor 1 (TNFR1) and exhibited comparable I?B? degradation with TNF?. However, in the absence of STAT3 nuclear accumulation of NF?B p65 with TNF? was attenuated and induction of the survival protein c-FLIPL was eliminated. Nonetheless, WT MEF were more sensitive to TNF?-induced death which was attributed to necrosis. Deletion of STAT3 decreased ROS formation induced by TNF? and serum deprivation. STAT3 deletion was associated with lower levels of complex I and rates of respiration. Relative to WT cells, mitochondria of STAT3 KO cells released significantly more cytochrome c in response to oxidative stress and had greater caspase 3 cleavage due to serum deprivation. Our findings are consistent with STAT3 being important for mitochondrial function and cell viability by ensuring mitochondrial integrity and the expression of pro-survival genes. PMID:24548419

  15. IL-6 Trans-signaling-STAT3 Pathway Mediates ECM and Cellular Proliferation in Fibroblasts from Hypertrophic Scar

    PubMed Central

    Ray, Sutapa; Ju, Xiaoxi; Sun, Hong; Finnerty, Celeste C; Herndon, David N; Brasier, Allan R

    2012-01-01

    The molecular mechanisms behind the pathogenesis of post-burn hypertrophic scar (HS) remain unclear. Here, we investigate the role of interleukin-6 (IL-6) trans-signaling-STAT3 pathway in HS fibroblasts (HSF) derived from burned-induced HS skin. HSF showed increased Tyr 705 STAT3 phosphorylation over normal fibroblast (NF) after IL-6•IL-6R? stimulation by immunoassays. The endogenous STAT3 target gene, SOCS3, was upregulated in HSF and showed increased STAT3 binding on its promoter relative to NF in Chromatin Immunoprecipitation assay. We observed that the cell surface signaling transducer glycoprotein 130 is upregulated in HSF using Q-RT-PCR and flow cytometry. The production of excessive extracellular matrix (ECM), including the expression of alpha2 (1) procollagen (Col1A2) and fibronectin 1 (FN) were seen in HSFs. A STAT3 peptide inhibitor abrogated FN and Col1A2 gene expression in HSF indicating involvement of STAT3 in ECM production. The cellular proliferation markers Cyclin D1, Bcl-Xl and c-Myc were also upregulated in HSF and knockdown of STAT3 by siRNA attenuated c-Myc expression indicating the essential role of STAT3 in fibroblast proliferation. Taken together, our results suggest that the IL-6-trans-signaling-STAT3 pathway may play an integral role in HS pathogenesis and disruption of this pathway could be a potential therapeutic strategy for the treatment of burn-induced HS. PMID:23303450

  16. M-HIFU Inhibits Tumor Growth, Suppresses STAT3 Activity and Enhances Tumor Specific Immunity in a Transplant Tumor Model of Prostate Cancer

    PubMed Central

    Huang, Xiaoyi; Yuan, Fang; Liang, Meihua; Lo, Hui-Wen; Shinohara, Mari L.; Robertson, Cary; Zhong, Pei

    2012-01-01

    Objective In this study, we explored the use of mechanical high intensity focused ultrasound (M-HIFU) as a neo-adjuvant therapy prior to surgical resection of the primary tumor. We also investigated the role of signal transducer and activator of transcription 3 (STAT3) in M-HIFU elicited anti-tumor immune response using a transplant tumor model of prostate cancer. Methods RM-9, a mouse prostate cancer cell line with constitutively activated STAT3, was inoculated subcutaneously in C57BL/6J mice. The tumor-bearing mice (with a maximum tumor diameter of 5?6 mm) were treated by M-HIFU or sham exposure two days before surgical resection of the primary tumor. Following recovery, if no tumor recurrence was observed in 30 days, tumor rechallenge was performed. The growth of the rechallenged tumor, survival rate and anti-tumor immune response of the animal were evaluated. Results No tumor recurrence and distant metastasis were observed in both treatment groups employing M-HIFU + surgery and surgery alone. However, compared to surgery alone, M-HIFU combined with surgery were found to significantly inhibit the growth of rechallenged tumors, down-regulate intra-tumoral STAT3 activities, increase cytotoxic T cells in spleens and tumor draining lymph nodes (TDLNs), and improve the host survival. Furthermore, M-HIFU combined with surgery was found to significantly decrease the level of immunosuppression with concomitantly increased number and activities of dendritic cells, compared to surgery alone. Conclusion Our results demonstrate that M-HIFU can inhibit STAT3 activities, and when combined synergistically with surgery, may provide a novel and promising strategy for the treatment of prostate cancers. PMID:22911830

  17. JAK1/STAT3 activation directly inhibits IL-12 production in dendritic cells by preventing CDK9/P-TEFb recruitment to the p35 promoter.

    PubMed

    Wagner, Andreas H; Conzelmann, Michael; Fitzer, Franziska; Giese, Thomas; Gülow, Karsten; Falk, Christine S; Krämer, Oliver H; Dietrich, Sascha; Hecker, Markus; Luft, Thomas

    2015-07-01

    Inhibition of Janus-activated kinase-1 (JAK1) is a promising clinical concept for post-transplant immunosuppression and autoimmunity. However, it also raises concerns regarding possible immunosuppressive side effects. Our study investigates JAK1 signalling in the context of CD40L and bacterially activated human MoDC using siRNA and biological inhibitors. We demonstrate that strong stimuli (e.g. intact Escherichia coli or LPS in addition to IL-1?) induce IL-12p70 via a ROS/RELA/CDK9 pathway that is inhibited by simultaneous JAK1/STAT3 signalling. Transcription is effective if RELA recruits the positive transcription elongation factor b (P-TEFb) component CDK9 to a combined RELA/STAT3 binding site -50 to -20bp upstream of the start site of the IL-12p35 promoter. STAT3 simultaneously attaches to this site and inhibits CDK9 binding. In the presence of IFN?, JAK1/2 inhibitors block STAT1/IRF1/IRF8-dependent activation and simultaneously enhance CDK9-dependent activation signals. This inverse regulation of IFN?- vs. E. coli-induced cytokine production by JAK inhibitors including Ruxolitinib was similarly observed for IL-6 and TNF-? production, but not for IL-10 production. Thus, JAK1 inhibition enhances IL-12p70 production in this context by increased DNA binding of CDK9. In contrast, weak RELA-activation signals (CD40L, LPS) depended on IFN-? induced STAT1/IRF1/IRF8 co-signalling, which was completely blocked by JAK inhibitors as reported before. Our results suggest a novel molecular mechanism of how cytokine responses to invading pathogens are separable from IFN?-dependent autoimmunity by targeting JAK1/STAT3 activation. PMID:25931145

  18. Oncostatin M overexpression induces matrix deposition, STAT3 activation, and SMAD1 Dysregulation in lungs of fibrosis-resistant BALB/c mice.

    PubMed

    Wong, Steven; Botelho, Fernando M; Rodrigues, Rebecca M; Richards, Carl D

    2014-09-01

    Adverse health outcomes in pulmonary fibrosis are associated with extracellular matrix (ECM) accumulation. Although transforming growth factor-? (TGF-?) has been reported to be an important regulator of fibrosis pathogenesis, TGF-?-independent pathways may also be involved. Here, we investigated responses of putative relatively fibrosis-resistant BALB/c mice to transient pulmonary overexpression of oncostatin M (OSM) using an adenovirus vector encoding OSM (AdOSM) and compared responses with the relatively fibrosis-prone C57Bl/6 strain. Interestingly, BALB/c mice showed similar ECM accumulation and collagen 1A1 and 3A1 mRNA elevation to C57Bl/6 mice 7 days after endotracheal administration of AdOSM. TGF-?1 mRNA levels and pSMAD2 signal were not regulated in either strain in total lung extracts. In contrast to C57Bl/6 mice, BALB/c mice lacked eosinophil, Th2 cytokine, and pro-inflammatory cytokine elevation in the broncholveolar space. OSM overexpression induced STAT3 activation and SMAD1/5/8 signaling suppression in lung from both mice strains, which was associated with a downregulation of BMPR2 and BMP ligands, and increased expression of the BMP antagonist gremlin. Although we also observed STAT3 activation and SMAD1/5/8 signaling suppression in mouse lung fibroblast cultures in vitro upon OSM stimulation, immunohistochemistry analyses indicated that the AdOSM-induced pSMAD1/5/8 signal suppression was primarily localized to the airway epithelium. Other gp130 cytokines including IL-6, LIF, CT-1, but not IL-31, also induced STAT3 activation and SMAD1/5/8 signaling suppression in C10 mouse lung epithelial cells and BEAS 2B bronchial epithelial cells, and we found that pharmacological inhibition of STAT3 activation reversed OSM-induced SMAD1/5/8 signaling suppression in vitro. The results demonstrate that OSM induces ECM accumulation in fibrosis-resistant BALB/c mouse lung in the absence of Th2 inflammation or TGF-? signaling, and highlight a dichotomy of STAT3 activation versus SMAD1 suppression in this process. PMID:24933422

  19. Unveiling the Association of STAT3 and HO-1 in Prostate Cancer: Role beyond Heme Degradation1

    PubMed Central

    Elguero, Belen; Gueron, Geraldine; Giudice, Jimena; Toscani, Martin A; De Luca, Paola; Zalazar, Florencia; Coluccio-Leskow, Federico; Meiss, Roberto; Navone, Nora; De Siervi, Adriana; Vazquez, Elba

    2012-01-01

    Activation of the androgen receptor (AR) is a key step in the development of prostate cancer (PCa). Several mechanisms have been identified in AR activation, among them signal transducer and activator of transcription 3 (STAT3) signaling. Disruption of STAT3 activity has been associated to cancer progression. Recent studies suggest that heme oxygenase 1 (HO-1) may play a key role in PCa that may be independent of its catalytic function. We sought to explore whether HO-1 operates on AR transcriptional activity through the STAT3 axis. Our results display that HO-1 induction in PCa cells represses AR activation by decreasing the prostate-specific antigen (PSA) promoter activity and mRNA levels. Strikingly, this is the first report to show by chromatin immunoprecipitation analysis that HO-1 associates to gene promoters, revealing a novel function for HO-1 in the nucleus. Furthermore, HO-1 and STAT3 directly interact as determined by co-immunoprecipitation studies. Forced expression of HO-1 increases STAT3 cytoplasmic retention. When PCa cells were transfected with a constitutively active STAT3 mutant, PSA and STAT3 downstream target genes were abrogated under hemin treatment. Additionally, a significant decrease in pSTAT3 protein levels was detected in the nuclear fraction of these cells. Confocal microscopy images exhibit a decreased rate of AR/STAT3 nuclear co-localization under hemin treatment. In vivo studies confirmed that STAT3 nuclear delimitation was significantly decreased in PC3 tumors overexpressing HO-1 grown as xenografts in nude mice. These results provide a novel function for HO-1 down-modulating AR transcriptional activity in PCa, interfering with STAT3 signaling, evidencing its role beyond heme degradation. PMID:23226098

  20. Autoimmunity, hypogammaglobulinemia, lymphoproliferation, and mycobacterial disease in patients with activating mutations in STAT3.

    PubMed

    Haapaniemi, Emma M; Kaustio, Meri; Rajala, Hanna L M; van Adrichem, Arjan J; Kainulainen, Leena; Glumoff, Virpi; Doffinger, Rainer; Kuusanmäki, Heikki; Heiskanen-Kosma, Tarja; Trotta, Luca; Chiang, Samuel; Kulmala, Petri; Eldfors, Samuli; Katainen, Riku; Siitonen, Sanna; Karjalainen-Lindsberg, Marja-Liisa; Kovanen, Panu E; Otonkoski, Timo; Porkka, Kimmo; Heiskanen, Kaarina; Hänninen, Arno; Bryceson, Yenan T; Uusitalo-Seppälä, Raija; Saarela, Janna; Seppänen, Mikko; Mustjoki, Satu; Kere, Juha

    2015-01-22

    The signal transducer and activator of transcription (STAT) family of transcription factors orchestrate hematopoietic cell differentiation. Recently, mutations in STAT1, STAT5B, and STAT3 have been linked to development of immunodysregulation polyendocrinopathy enteropathy X-linked-like syndrome. Here, we immunologically characterized 3 patients with de novo activating mutations in the DNA binding or dimerization domains of STAT3 (p.K392R, p.M394T, and p.K658N, respectively). The patients displayed multiorgan autoimmunity, lymphoproliferation, and delayed-onset mycobacterial disease. Immunologically, we noted hypogammaglobulinemia with terminal B-cell maturation arrest, dendritic cell deficiency, peripheral eosinopenia, increased double-negative (CD4(-)CD8(-)) T cells, and decreased natural killer, T helper 17, and regulatory T-cell numbers. Notably, the patient harboring the K392R mutation developed T-cell large granular lymphocytic leukemia at age 14 years. Our results broaden the spectrum of phenotypes caused by activating STAT3 mutations, highlight the role of STAT3 in the development and differentiation of multiple immune cell lineages, and strengthen the link between the STAT family of transcription factors and autoimmunity. PMID:25349174

  1. Autoimmunity, hypogammaglobulinemia, lymphoproliferation, and mycobacterial disease in patients with activating mutations in STAT3

    PubMed Central

    Haapaniemi, Emma M.; Kaustio, Meri; Rajala, Hanna L. M.; van Adrichem, Arjan J.; Kainulainen, Leena; Glumoff, Virpi; Doffinger, Rainer; Kuusanmäki, Heikki; Heiskanen-Kosma, Tarja; Trotta, Luca; Chiang, Samuel; Kulmala, Petri; Eldfors, Samuli; Katainen, Riku; Siitonen, Sanna; Karjalainen-Lindsberg, Marja-Liisa; Kovanen, Panu E.; Otonkoski, Timo; Porkka, Kimmo; Heiskanen, Kaarina; Hänninen, Arno; Bryceson, Yenan T.; Uusitalo-Seppälä, Raija; Saarela, Janna; Seppänen, Mikko; Kere, Juha

    2015-01-01

    The signal transducer and activator of transcription (STAT) family of transcription factors orchestrate hematopoietic cell differentiation. Recently, mutations in STAT1, STAT5B, and STAT3 have been linked to development of immunodysregulation polyendocrinopathy enteropathy X-linked–like syndrome. Here, we immunologically characterized 3 patients with de novo activating mutations in the DNA binding or dimerization domains of STAT3 (p.K392R, p.M394T, and p.K658N, respectively). The patients displayed multiorgan autoimmunity, lymphoproliferation, and delayed-onset mycobacterial disease. Immunologically, we noted hypogammaglobulinemia with terminal B-cell maturation arrest, dendritic cell deficiency, peripheral eosinopenia, increased double-negative (CD4?CD8?) T cells, and decreased natural killer, T helper 17, and regulatory T-cell numbers. Notably, the patient harboring the K392R mutation developed T-cell large granular lymphocytic leukemia at age 14 years. Our results broaden the spectrum of phenotypes caused by activating STAT3 mutations, highlight the role of STAT3 in the development and differentiation of multiple immune cell lineages, and strengthen the link between the STAT family of transcription factors and autoimmunity. PMID:25349174

  2. Leukemia. Author manuscript STAT3 transcription factor is constitutively activated and is oncogenic in

    E-print Network

    Paris-Sud XI, Université de

    and is oncogenic in nasal-type NK/T-cell lymphoma Coppo Paul 1 2 3 * , Gouilleux-Gruart Val rieé 4 , Huang Yenlin 8 results suggest that STAT3 protein has a major role in the oncogenic process of nasal-type NK cell

  3. Selective inhibition of the function of tyrosine-phosphorylated STAT3 with a phosphorylation site-specific intrabody

    PubMed Central

    Koo, Mi Young; Park, Jiyoung; Lim, Jung Mi; Joo, Sei Yoon; Shin, Seung-Pil; Shim, Hyun Bo; Chung, Junho; Kang, Dongmin; Woo, Hyun Ae; Rhee, Sue Goo

    2014-01-01

    Signal transducer and activator of transcription 3 (STAT3) is a multifunctional protein that participates in signaling pathways initiated by various growth factors and cytokines. It exists in multiple forms including those phosphorylated on Tyr705 (pYSTAT3) or Ser727 (pSSTAT3) as well as the unphosphorylated protein (USTAT3). In addition to the canonical transcriptional regulatory role of pYSTAT3, both USTAT3 and pSSTAT3 function as transcriptional regulators by binding to distinct promoter sites and play signaling roles in the cytosol or mitochondria. The roles of each STAT3 species in different biological processes have not been readily amenable to investigation, however. We have now prepared an intrabody that binds specifically and with high affinity to the tyrosine-phosphorylated site of pYSTAT3. Adenovirus-mediated expression of the intrabody in HepG2 cells as well as mouse liver blocked both the accumulation of pYSTAT3 in the nucleus and the production of acute phase response proteins induced by interleukin-6. Intrabody expression did not affect the overall accumulation of pSSTAT3 induced by interleukin-6 or phorbol 12-myristate 13-acetate (PMA), the PMA-induced expression of the c-Fos gene, or the PMA-induced accumulation of pSSTAT3 specifically in mitochondria. In addition, it had no effect on interleukin-6–induced expression of the gene for IFN regulatory factor 1, a downstream target of STAT1. Our results suggest that the engineered intrabody is able to block specifically the downstream effects of pYSTAT3 without influencing those of pSSTAT3, demonstrating the potential of intrabodies as tools to dissect the cellular functions of specific modified forms of proteins that exist as multiple species. PMID:24733900

  4. A Novel Role of the STAT3 Pathway in Brain Inflammation-induced Human Neural Progenitor Cell Differentiation

    PubMed Central

    Chen, Emily; Xu, Dongsheng; Lan, Xiqian; Jia, Beibei; Sun, Lijun; Zheng, Jialin C.; Peng, Hui

    2014-01-01

    Brain inflammation is a primary pathological driving force of many neurodegenerative disorders. In the destructive process, pro-inflammatory cytokines (IL-1? and TNF-?), are robustly released, affecting normal neural progenitor cell (NPC) differentiation, and resulting in a vast number of astrocytes and a diminished neural population. A counteractive mechanism is still unknown. In this study, we have identified a link between brain inflammation and the signal transducer and activator of transcription 3 (STAT3) pathway: IL-1? and TNF-? induce STAT3 activation in NPCs. Then to investigate STAT3’s effects on NPC fate, we observed that an inhibition of STAT3 expression by siRNA inhibited astrocytic differentiation and increased neuronal differentiation of human NPCs in fetal bovine serum (FBS)-induced astrocyte differentiation condition. Furthermore, STAT3-targeting siRNA abrogated IL-1? and TNF-?-induced astrocyte differentiation and partially restored neuronal differentiation. Elimination of STAT3 expression also countered IL-1? and TNF-?-induced inhibition of proneural bHLH genes, mammalian achaete-schute homologue-1 (Mash1), Neurogenin1 (Ngn1), and Neurogenin 2 (Ngn2). These data suggest that a suppression of STAT3 during brain inflammation would inhibit astrogliogenesis and promote neurogenesis. Thus, STAT3 could be a potential target of drug therapy for neurodegenerative disorders. PMID:23971732

  5. Dendritic cells from Crohn's disease patients show aberrant STAT1 and STAT3 signaling.

    PubMed

    Nieminen, Janne K; Niemi, Mirja; Sipponen, Taina; Salo, Harri M; Klemetti, Paula; Färkkilä, Martti; Vakkila, Jukka; Vaarala, Outi

    2013-01-01

    Abnormalities of dendritic cells (DCs) and STAT proteins have been reported in Crohn's disease (CD). Studies on JAK/STAT signaling in DCs are, however, lacking in CD. We applied a flowcytometric single-cell-based phosphoepitope assay to evaluate STAT1 and STAT3 pathways in DC subsets from CD patients. In addition, circulating DC counts were determined, together with the activation-related immunophenotype. We found that IL-6- and IFN-?-induced STAT3 phosphorylation and IFN-?-induced STAT1 phosphorylation were impaired in plasmacytoid DCs (pDCs) from CD patients (P = 0.005, P = 0.013, and P = 0.006, respectively). In myeloid DCs (mDCs), IFN-?-induced STAT1 and STAT3 phosphorylation were attenuated (P<0.001 and P = 0.048, respectively), but IL-10-induced STAT3 phosphorylation was enhanced (P = 0.026). IFN-?-induced STAT1 signaling was intact in both DC subtypes. Elevated plasma IL-6 levels were detected in CD (P = 0.004), which strongly correlated with disease activity (? = 0.690, P<0.001) but not with IL-6-induced STAT3 phosphorylation. The numbers of pDCs and BDCA3+ mDCs were decreased, and CD40 expression on CD1c+ mDCs was increased in CD. When elucidating the effect of IL-6 signaling on pDC function, we observed that IL-6 treatment of healthy donor pDCs affected the maturation of and modified the T-cell priming by pDCs, favoring Th2 over Th1 type of response and the expression of IL-10 in T cells. Our results implicate DC signaling in human CD. Reduced IL-6 responsiveness in pDCs, together with the attenuated IFN-?-induced signaling in both DC subtypes, may contribute to the immunological dysregulation in CD patients. PMID:23950992

  6. Prosapogenin A induces apoptosis in human cancer cells in vitro via inhibition of the STAT3 signaling pathway and glycolysis

    PubMed Central

    WANG, TIAN-XIAO; ZHANG, ZHONG-QING; CONG, YUE; SHI, XIAO-YAN; LIU, YING-HUA; ZHAO, FANG-LI

    2013-01-01

    Signal transducer and activator of transcription 3 (STAT3) is considered to be an oncogene. Blocking STAT3 signaling may induce growth arrest and apoptosis in different types of tumors. Cancer cells utilize the glycolytic pathway to maintain cell growth even when adequate oxygen is present. Glycolysis inhibition is a potential therapeutic modality. In the present study, the effects of Prosapogenin A (PSA) from the traditional Chinese medicine, Veratrum, on apoptosis, the STAT3 signaling pathway and glycometabolism in cancer cells were investigated. The results indicated that PSA induced growth inhibition and apoptosis in HeLa, HepG2 and MCF-7 cells. PSA inhibited the STAT3 signaling pathway and modulated the expression of glycometabolism-related genes. The results indicate that the inhibition of the STAT3 signaling and glycometabolism pathways contributes to the PSA-mediated apoptosis of HeLa, HepG2 and MCF-7 cells. PMID:24179517

  7. MicroRNA let-7 downregulates STAT3 phosphorylation in pancreatic cancer cells by increasing SOCS3 expression.

    PubMed

    Patel, Kripa; Kollory, Anita; Takashima, Asami; Sarkar, Sibaji; Faller, Douglas V; Ghosh, Sajal K

    2014-05-28

    Although dispensable for normal pancreatic function, STAT3 signaling is frequently activated in pancreatic cancers. Consistent downregulation of expression of microRNA let-7 is also characteristic of pancreatic ductal adenocarcinoma (PDAC) biopsy specimens. We demonstrate in this study that re-expression of let-7 in poorly-differentiated PDAC cell lines reduced phosphorylation/activation of STAT3 and its downstream signaling events and reduced the growth and migration of PDAC cells. Let-7 re-expression did not repress expression of STAT3 protein or its activator cytokine interleukin 6 (IL-6). However, let-7 re-expression enhanced cytoplasmic expression of suppressor of cytokine signaling 3 (SOCS3), which blocks STAT3 activation by JAK2. Our study thus identified a mechanism by which STAT3 signaling can be inhibited in pancreatic cancer cells by modifying let-7 expression. PMID:24491408

  8. MicroRNA Let-7 Downregulates STAT3 Phosphorylation in Pancreatic Cancer Cells by Increasing SOCS3 Expression

    PubMed Central

    Patel, Kripa; Kollory, Anita; Takashima, Asami; Sarkar, Sibaji; Faller, Douglas V.; Ghosh, Sajal K

    2014-01-01

    Although dispensable for normal pancreatic function, STAT3 signaling is frequently activated in pancreatic cancers. Consistent downregulation of expression of microRNA let-7 is also characteristic of pancreatic ductal adenocarcinoma (PDAC) biopsy specimens. We demonstrate in this study that re-expression of let-7 in poorly-differentiated PDAC cell lines reduced phosphorylation/activation of STAT3 and its downstream signaling events and reduced the growth and migration of PDAC cells. Let-7 re-expression did not repress expression of STAT3 protein or its activator cytokine interleukin 6 (IL-6). However, let-7 re-expression enhanced cytoplasmic expression of suppressor of cytokine signaling 3 (SOCS3), which blocks STAT3 activation by JAK2. Our study thus identified a mechanism by which STAT3 signaling can be inhibited in pancreatic cancer cells by modifying let-7 expression. PMID:24491408

  9. Overexpression of miR -155 Promotes Proliferation and Invasion of Human Laryngeal Squamous Cell Carcinoma via Targeting SOCS1 and STAT3

    PubMed Central

    Zhao, Xu-dong; Zhang, Wei; Liang, Hong-jun; Ji, Wen-yue

    2013-01-01

    MicroRNA155 plays an important role in many solid malignancies. Expression and function of miR-155 in laryngeal carcinoma have not been fully understood. This study aims to investigate the expression and function of miR-155 in laryngeal squamous cell carcinoma (LSCC), the relationship between miR-155 and its downstream target suppressor of cytokine signaling 1 (SOCS1)-STAT3 pathway, and the related clinicopathological factors. Sixty-three samples of laryngeal squamous cell carcinoma and twenty-one samples of control mucosa obtained from total laryngectomy cases were analyzed using Western blot analysis and real-time PCR. Hep-2 cells were cultured and transfected with miR-155 mimic and ASO. Cell proliferation, migration and invasion assays were used to determine the role of miR-155 in regulation of LSCC growth, migration, and invasion, respectively. The expression levels of miR-155 in LSCC were significantly higher than those in the control mucosa tissues. Downregulation of SOCS1 expression and elevated expression of STAT3 were also observed in LSCC. The relevance of the three factors were statistically significant. Moreover, knockdown of miR-155 elevated SOCS1expression level, suppressed STAT3 expression, and inhibited hep-2 cells growth, migration and invasion. Whereas overexpression of miR-155 inhibited SOCS1expression, elevated STAT3 expression, and promoted hep-2 cells growth, migration and invasion. Furthermore, the miR-155 levels in T3 T4 stages, and poor/moderate cell differentiation were significantly higher than those in T2 stage and higher degree of cell differentiation. The STAT3 protein in poor/moderate cell differentiation was significantly higher than those in higher degree of cell differentiation. We firstly demonstrated the aberrant expression and function of miR-155 and itsdownstream targets in LSCC. The current findings suggest that miR-155 play promotingrole during the development of LSCC, and miR-155 may be a useful marker for the prognosis and assessment of therapeutic effects. PMID:23437123

  10. Identification of STAT1 and STAT3 Specific Inhibitors Using Comparative Virtual Screening and Docking Validation

    PubMed Central

    Szelag, Malgorzata; Czerwoniec, Anna; Wesoly, Joanna; Bluyssen, Hans A. R.

    2015-01-01

    Signal transducers and activators of transcription (STATs) facilitate action of cytokines, growth factors and pathogens. STAT activation is mediated by a highly conserved SH2 domain, which interacts with phosphotyrosine motifs for specific STAT-receptor contacts and STAT dimerization. The active dimers induce gene transcription in the nucleus by binding to a specific DNA-response element in the promoter of target genes. Abnormal activation of STAT signaling pathways is implicated in many human diseases, like cancer, inflammation and auto-immunity. Searches for STAT-targeting compounds, exploring the phosphotyrosine (pTyr)-SH2 interaction site, yielded many small molecules for STAT3 but sparsely for other STATs. However, many of these inhibitors seem not STAT3-specific, thereby questioning the present modeling and selection strategies of SH2 domain-based STAT inhibitors. We generated new 3D structure models for all human (h)STATs and developed a comparative in silico docking strategy to obtain further insight into STAT-SH2 cross-binding specificity of a selection of previously identified STAT3 inhibitors. Indeed, by primarily targeting the highly conserved pTyr-SH2 binding pocket the majority of these compounds exhibited similar binding affinity and tendency scores for all STATs. By comparative screening of a natural product library we provided initial proof for the possibility to identify STAT1 as well as STAT3-specific inhibitors, introducing the ‘STAT-comparative binding affinity value’ and ‘ligand binding pose variation’ as selection criteria. In silico screening of a multi-million clean leads (CL) compound library for binding of all STATs, likewise identified potential specific inhibitors for STAT1 and STAT3 after docking validation. Based on comparative virtual screening and docking validation, we developed a novel STAT inhibitor screening tool that allows identification of specific STAT1 and STAT3 inhibitory compounds. This could increase our understanding of the functional role of these STATs in different diseases and benefit the clinical need for more drugable STAT inhibitors with high specificity, potency and excellent bioavailability. PMID:25710482

  11. Identification of STAT1 and STAT3 specific inhibitors using comparative virtual screening and docking validation.

    PubMed

    Szelag, Malgorzata; Czerwoniec, Anna; Wesoly, Joanna; Bluyssen, Hans A R

    2015-01-01

    Signal transducers and activators of transcription (STATs) facilitate action of cytokines, growth factors and pathogens. STAT activation is mediated by a highly conserved SH2 domain, which interacts with phosphotyrosine motifs for specific STAT-receptor contacts and STAT dimerization. The active dimers induce gene transcription in the nucleus by binding to a specific DNA-response element in the promoter of target genes. Abnormal activation of STAT signaling pathways is implicated in many human diseases, like cancer, inflammation and auto-immunity. Searches for STAT-targeting compounds, exploring the phosphotyrosine (pTyr)-SH2 interaction site, yielded many small molecules for STAT3 but sparsely for other STATs. However, many of these inhibitors seem not STAT3-specific, thereby questioning the present modeling and selection strategies of SH2 domain-based STAT inhibitors. We generated new 3D structure models for all human (h)STATs and developed a comparative in silico docking strategy to obtain further insight into STAT-SH2 cross-binding specificity of a selection of previously identified STAT3 inhibitors. Indeed, by primarily targeting the highly conserved pTyr-SH2 binding pocket the majority of these compounds exhibited similar binding affinity and tendency scores for all STATs. By comparative screening of a natural product library we provided initial proof for the possibility to identify STAT1 as well as STAT3-specific inhibitors, introducing the 'STAT-comparative binding affinity value' and 'ligand binding pose variation' as selection criteria. In silico screening of a multi-million clean leads (CL) compound library for binding of all STATs, likewise identified potential specific inhibitors for STAT1 and STAT3 after docking validation. Based on comparative virtual screening and docking validation, we developed a novel STAT inhibitor screening tool that allows identification of specific STAT1 and STAT3 inhibitory compounds. This could increase our understanding of the functional role of these STATs in different diseases and benefit the clinical need for more drugable STAT inhibitors with high specificity, potency and excellent bioavailability. PMID:25710482

  12. Homoharringtonine induces apoptosis and inhibits STAT3 via IL-6/JAK1/STAT3 signal pathway in Gefitinib-resistant lung cancer cells

    PubMed Central

    Cao, Wei; Liu, Ying; Zhang, Ran; Zhang, Bo; Wang, Teng; Zhu, Xianbing; Mei, Lin; Chen, Hongbo; Zhang, Hongling; Ming, Pinghong; Huang, Laiqiang

    2015-01-01

    Tyrosine kinase inhibitors (TKIs) are mostly used in non-small cell lung cancer (NSCLC) treatment. Unfortunately, treatment with Gefitinib for a period of time will result in drug resistance and cause treatment failure in clinic. Therefore, exploring novel compounds to overcome this resistance is urgently required. Here we investigated the antitumor effect of homoharringtonine (HHT), a natural compound extracted from Cephalotaxus harringtonia, on Gefitinib-resistant NSCLC cell lines in vitro and in vivo. NCI-H1975 cells with EGFR T790M mutation are more sensitive to HHT treatment compared with that of A549 cells with wild type EGFR. HHT inhibited cells growth, cell viability and colony formation, as well as induced cell apoptosis through mitochondria pathway. Furthermore, we explored the mechanism of HHT inhibition on NSCLC cells. Higher level of interleukin-6 (IL-6) existed in lung cancer patients and mutant EGFR and TGF? signal requires the upregulation of IL-6 through the gp130/JAK pathway to overactive STAT3, an oncogenic protein which has been considered as a potential target for cancer therapy. HHT reversiblely inhibited IL-6-induced STAT3 Tyrosine 705 phosphorylation and reduced anti-apoptotic proteins expression. Gefitinib-resistant NSCLC xenograft tests also confirmed the antitumor effect of HHT in vivo. Consequently, HHT has the potential in Gefitinib-resistant NSCLC treatment. PMID:26166037

  13. GDNF facilitates differentiation of the adult dentate gyrus-derived neural precursor cells into astrocytes via STAT3

    SciTech Connect

    Boku, Shuken, E-mail: shuboku@med.hokudai.ac.jp [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan)] [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan); Nakagawa, Shin [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan)] [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan); Takamura, Naoki [Pharmaceutical Laboratories, Dainippon Sumitomo Pharma Co. Ltd., Osaka (Japan)] [Pharmaceutical Laboratories, Dainippon Sumitomo Pharma Co. Ltd., Osaka (Japan); Kato, Akiko [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan)] [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan); Takebayashi, Minoru [Department of Psychiatry, National Hospital Organization Kure Medical Center, Kure (Japan)] [Department of Psychiatry, National Hospital Organization Kure Medical Center, Kure (Japan); Hisaoka-Nakashima, Kazue [Department of Pharmacology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima (Japan)] [Department of Pharmacology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima (Japan); Omiya, Yuki; Inoue, Takeshi; Kusumi, Ichiro [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan)] [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan)

    2013-05-17

    Highlights: •GDNF has no effect on ADP proliferation and apoptosis. •GDNF increases ADP differentiation into astrocyte. •A specific inhibitor of STAT3 decreases the astrogliogenic effect of GDNF. •STAT3 knockdown by lentiviral shRNA vector also decreases the astrogliogenic effect of GDNF. •GDNF increases the phosphorylation of STAT3. -- Abstract: While the pro-neurogenic actions of antidepressants in the adult hippocampal dentate gyrus (DG) are thought to be one of the mechanisms through which antidepressants exert their therapeutic actions, antidepressants do not increase proliferation of neural precursor cells derived from the adult DG. Because previous studies showed that antidepressants increase the expression and secretion of glial cell line-derived neurotrophic factor (GDNF) in C6 glioma cells derived from rat astrocytes and GDNF increases neurogenesis in adult DG in vivo, we investigated the effects of GDNF on the proliferation, differentiation and apoptosis of cultured neural precursor cells derived from the adult DG. Data showed that GDNF facilitated the differentiation of neural precursor cells into astrocytes but had no effect on their proliferation or apoptosis. Moreover, GDNF increased the phosphorylation of STAT3, and both a specific inhibitor of STAT3 and lentiviral shRNA for STAT3 decreased their differentiation into astrocytes. Taken together, our findings suggest that GDNF facilitates astrogliogenesis from neural precursor cells in adult DG through activating STAT3 and that this action might indirectly affect neurogenesis.

  14. Brevilin A, a Novel Natural Product, Inhibits Janus Kinase Activity and Blocks STAT3 Signaling in Cancer Cells

    PubMed Central

    Nan, Jing; Zhang, Xinxin; Qin, Xiaodong; Wang, Yuxin; Hou, Jianwen; Wang, Qin; Yang, Jinbo

    2013-01-01

    Signal abnormalities in human cells usually cause unexpected consequences for individual health. We focus on these kinds of events involved in JAK-STAT signal pathways, especially the ones triggered by aberrant activated STAT3, an oncoprotein which participates in essential processes of cell survival, growth and proliferation in many types of tumors, as well as immune diseases. By establishing a STAT3 signal based high-throughput drug screening system in human lung cancer A549 cells, we have screened a library from natural products which contained purified compounds from medicinal herbs. One compound, named Brevilin A, exhibited both strong STAT3 signal inhibition and STAT3 signal dependent cell growth inhibition. Further investigations revealed that Brevilin A not only inhibits STAT3 signaling but also STAT1 signaling for cytokines induced phosphorylation of STAT3 and STAT1 as well as the expression of their target genes. In addition, we found Brevilin A could attenuate the JAKs activity by blocking the JAKs tyrosine kinase domain JH1. The levels of cytokine induced phosphorylation of STATs and other substrates were dramatically reduced by treatment of Brevilin A. The roles of Brevilin A targeting on JAKs activity indicate that Brevilin A may not only be used as a STAT3 inhibitor but also a compound blocking other JAK-STAT hyperactivation. Thus, these findings provided a strong impetus for the development of selective JAK-STAT inhibitors and therapeutic drugs in order to improve survival of patients with hyperactivated JAKs and STATs. PMID:23704931

  15. Association of pSTAT3-VEGF signaling pathway with peritumoral edema in newly diagnosed glioblastoma: an immunohistochemical study

    PubMed Central

    Wang, Xing-Fu; Lin, Guo-Shi; Lin, Zhi-Xiong; Chen, Yu-Peng; Chen, Yao; Zhang, Jian-Dong; Tan, Wen-Long

    2014-01-01

    It is well recognized that peritumoral edema is vasogenic cerebral edema in malignant glioma, and vascular endothelial growth factor (VEGF) induced by phosphorylated signal transducer and activator of transcription factor 3 (pSTAT3) strongly contributes to tumor angiogenesis in glioblastoma. However, there is no study with regard to the correlation between pSTAT3 or VEGF and peritumoral edema. Such evidence may contribute to providing new targets for the management of peritumoral cerebral. In this study, newly diagnosed glioblastoma tissues from 84 patients were collected to investigate pSTAT3 and VEGF expression by immunohistochemistry, and peritumoral edema was detected by preoperative magnetic resonance imaging. We found that a significantly positive correlation emerged between VEGF and pSTAT3 expression (P = 0.000) in glioblastoma tissues, but they were not related to patient gender and age (P > 0.05); the expression of pSTAT3 and VEGF were associated with peritumoral edema extent (P = 0.005), but not with edema shape (P > 0.05). Therefore, the pSTAT3-VEGF signaling pathway, which is correlated with peritumoral edema extent, might be a regulatory mechanism in the course of peritumoral edema formation during glioblastoma tumorigenesis and progression, thereby suggesting that STAT3 inhibition might be helpful for alleviation of peritumoral cerebral edema. PMID:25337261

  16. The IL-10/STAT3-mediated anti-inflammatory response: recent developments and future challenges

    PubMed Central

    Hutchins, Andrew P.; Diez, Diego

    2013-01-01

    Inflammation is a fundamental response of the immune system whose successful termination involves the elimination of the invading pathogens, the resolution of inflammation and the repair of the local damaged tissue. In this context, the interleukin 10 (IL-10)-mediated anti-inflammatory response (AIR) represents an essential homeostatic mechanism that controls the degree and duration of inflammation. Here, we review recent work on the mechanistic characterization of the IL-10-mediated AIR on multiple levels: from the cataloguing of the in vivo genomic targets of STAT3 (the transcription factor downstream of IL-10) to the identification of specific co-factors that endow STAT3 with genomic-binding specificity, and how genomic and computational methods are being used to elucidate the regulatory mechanisms of this essential physiological response in macrophages. PMID:23943603

  17. Constitutive Activation of Stat3 Signaling Confers Resistance to Apoptosis in Human U266 Myeloma Cells

    Microsoft Academic Search

    Robyn Catlett-Falcone; Terry H Landowski; Marc M Oshiro; James Turkson; Alexander Levitzki; Rocco Savino; Gennaro Ciliberto; Lynn Moscinski; Jose Luis Fernández-Luna; Gabriel Nuñez; William S Dalton; Richard Jove

    1999-01-01

    Interleukin 6 (IL-6) is the major survival factor for myeloma tumor cells and induces signaling through the STAT proteins. We report that one STAT family member, Stat3, is constitutively activated in bone marrow mononuclear cells from patients with multiple myeloma and in the IL-6-dependent human myeloma cell line U266. Moreover, U266 cells are inherently resistant to Fas-mediated apoptosis and express

  18. Cucurbitacin I Inhibits Stat3 and Induces Apoptosis in Sézary Cells

    Microsoft Academic Search

    Marloes S van Kester; Jacoba J Out-Luiting; Peter A von dem Borne; Rein Willemze; Cornelis P Tensen; Maarten H Vermeer

    2008-01-01

    Sézary syndrome (Sz) is an aggressive cutaneous CD4+ T-cell lymphoma with tumor cells (Sz cells) localized in the skin, lymph nodes, and peripheral blood. Using western blotting, we demonstrate the expression of phosphorylated (P)-Stat3 in the Sz-derived cell line Seax, and in freshly isolated tumor cells from Sz patients (n=6). In Vitro overnight culture without exogenous cytokines results in decreased

  19. Prediction and Experimental Validation of Novel STAT3 Target Genes in Human Cancer Cells

    Microsoft Academic Search

    Young Min Oh; Jong Kyoung Kim; Yongwook Choi; Seungjin Choi; Joo-Yeon Yoo; Sridhar Hannenhalli

    2009-01-01

    The comprehensive identification of functional transcription factor binding sites (TFBSs) is an important step in understanding complex transcriptional regulatory networks. This study presents a motif-based comparative approach, STAT-Finder, for identifying functional DNA binding sites of STAT3 transcription factor. STAT-Finder combines STAT-Scanner, which was designed to predict functional STAT TFBSs with improved sensitivity, and a motif-based alignment to minimize false positive

  20. LIF-JAK1-STAT3 signaling delays contact inhibition of human corneal endothelial cells.

    PubMed

    Liu, Xin; Tseng, Scheffer Cg; Zhang, Ming-Chang; Chen, Szu-Yu; Tighe, Sean; Lu, Wen-Juan; Zhu, Ying-Ting

    2015-04-18

    Human corneal endothelial cells (HCECs) responsible for corneal transparency have limited proliferative capacity in vivo because of "contact-inhibition." This feature has hampered the ability to engineer HCECs for transplantation. Previously we have reported an in vitro model of HCECs in which contact inhibition was re-established at Day 21, even though cell junction and cell matrix interaction were not perturbed during isolation. Herein, we observe that such HCEC monolayers continue to expand and retain a normal phenotype for 2 more weeks if cultured in a leukemia inhibitory factor (LIF)-containing serum-free medium. Such expansion is accompanied initially by upregulation of Cyclin E2 colocalized with nuclear translocation of phosphorylated retinoblastoma tumor suppressor (p-Rb) at Day 21 followed by a delay in contact inhibition through activation of LIF-Janus kinase1 (JAK1)-signal transducer and activator of transcription 3 (STAT3) signaling at Day 35. The LIF-JAK1-STAT3 signaling is coupled with upregulation of E2F2 colocalized with nuclear p-Rb and with concomitant downregulation of p16(INK4a), of which upregulation is linked to senescence. Hence, activation of LIF-JAK1-STAT3 signaling to delay contact inhibition can be used as another strategy to facilitate engineering of HCEC grafts to solve the unmet global shortage of corneal grafts. PMID:25695744

  1. Inhibition of cellular STAT3 synergizes with the cytomegalovirus kinase inhibitor maribavir to disrupt infection.

    PubMed

    Reitsma, Justin M; Terhune, Scott S

    2013-11-01

    Therapeutic strategies controlling human cytomegalovirus (hCMV) infection are limited due to adverse side effects and emergence of antiviral resistance variants. A compound being evaluated for treating hCMV disease is maribavir (MBV) which disrupts replication by inhibiting the viral kinase pUL97. Previous studies have demonstrated that the antiviral activity of MBV is sensitive to the proliferation state of the infected cell. In these studies, we were interested in determining whether inhibition of the pro-proliferative transcription factor, signal transducer and activator of transcription-3 (STAT3), could influence the antiviral activity of MBV. The addition of the STAT3 inhibitor, S3i-201, during infection altered hCMV-mediated changes in cell cycle protein expression. Upon combining S3i-201 with MBV, our data suggest that STAT3 inhibition is acting synergistically with MBV to inhibit infection in vitro. Furthermore, specific concentrations of S3i-201 and MBV induced caspase-dependent death of infected but not uninfected cell. Our studies suggest that treating infection with both S3i-201 and MBV is a novel approach to inhibit hCMV replication. PMID:24070820

  2. Anti-cancer effect of bee venom toxin and melittin in ovarian cancer cells through induction of death receptors and inhibition of JAK2/STAT3 pathway.

    PubMed

    Jo, Miran; Park, Mi Hee; Kollipara, Pushpa Saranya; An, Byeong Jun; Song, Ho Sueb; Han, Sang Bae; Kim, Jang Heub; Song, Min Jong; Hong, Jin Tae

    2012-01-01

    We investigated whether bee venom and melittin, a major component of bee venom, inhibit cell growth through enhancement of death receptor expressions in the human ovarian cancer cells, SKOV3 and PA-1. Bee venom (1-5 ?g/ml) and melittin (0.5-2 ?g/ml) inhibited the growth of SKOV3 and PA-1 ovarian cancer cells by the induction of apoptotic cell death in a dose dependent manner. Consistent with apoptotic cell death, expression of death receptor (DR) 3 and DR6 was increased in both cancer cells, but expression of DR4 was increased only in PA-1 cells. Expression of DR downstream pro-apoptotic proteins including caspase-3, 8, and Bax was concomitantly increased, but the phosphorylation of JAK2 and STAT3 and the expression of Bcl-2 were inhibited by treatment with bee venom and melittin in SKOV3 and PA-1 cells. Expression of cleaved caspase-3 was increased in SKOV3, but cleaved caspase-8 was increased in PA-1 cells. Moreover, deletion of DR3, DR4, and DR6 by small interfering RNA significantly reversed bee venom and melittin-induced cell growth inhibitory effect as well as down regulation of STAT3 by bee venom and melittin in SKOV3 and PA-1 ovarian cancer cell. These results suggest that bee venom and melittin induce apoptotic cell death in ovarian cancer cells through enhancement of DR3, DR4, and DR6 expression and inhibition of STAT3 pathway. PMID:22027265

  3. Glial Scar Borders Are Formed by Newly Proliferated, Elongated Astrocytes That Interact to Corral Inflammatory and Fibrotic Cells via STAT3-Dependent Mechanisms after Spinal Cord Injury

    PubMed Central

    Anderson, Mark A.; Song, Bingbing; Levine, Jaclynn; Fernandez, Ana; Gray-Thompson, Zachary; Ao, Yan

    2013-01-01

    Astroglial scars surround damaged tissue after trauma, stroke, infection, or autoimmune inflammation in the CNS. They are essential for wound repair, but also interfere with axonal regrowth. A better understanding of the cellular mechanisms, regulation, and functions of astroglial scar formation is fundamental to developing safe interventions for many CNS disorders. We used wild-type and transgenic mice to quantify and dissect these parameters. Adjacent to crush spinal cord injury (SCI), reactive astrocytes exhibited heterogeneous phenotypes as regards proliferation, morphology, and chemistry, which all varied with distance from lesions. Mature scar borders at 14 d after SCI consisted primarily of newly proliferated astroglia with elongated cell processes that surrounded large and small clusters of inflammatory, fibrotic, and other cells. During scar formation from 5 to 14 d after SCI, cell processes deriving from different astroglia associated into overlapping bundles that quantifiably reoriented and organized into dense mesh-like arrangements. Selective deletion of STAT3 from astroglia quantifiably disrupted the organization of elongated astroglia into scar borders, and caused a failure of astroglia to surround inflammatory cells, resulting in increased spread of these cells and neuronal loss. In cocultures, wild-type astroglia spontaneously corralled inflammatory or fibromeningeal cells into segregated clusters, whereas STAT3-deficient astroglia failed to do so. These findings demonstrate heterogeneity of reactive astroglia and show that scar borders are formed by newly proliferated, elongated astroglia, which organize via STAT3-dependent mechanisms to corral inflammatory and fibrotic cells into discrete areas separated from adjacent tissue that contains viable neurons. PMID:23904622

  4. Integrated analysis reveals that STAT3 is central to the crosstalk between HER/ErbB receptor signaling pathways in human mammary epithelial cells

    SciTech Connect

    Gong, Chunhong; Zhang, Yi; Shankaran, Harish; Resat, Haluk

    2015-01-01

    Human epidermal growth factor receptors (HER, also known as ErbB) drive cellular proliferation, pro-survival and stress responses by activating several downstream kinases, in particular ERK, p38, JNK (SAPK), the PI3K/AKT, as well as various transcriptional regulators such as STAT3. When co-expressed, first three members of HER family (HER1-3) can form homo- and hetero-dimers. Based on the considerable evidence which suggest that every receptor dimer activates intracellular signaling pathways differentially, we hypothesized that the HER dimerization pattern is a better predictor of downstream signaling than the total receptor activation levels. We validated our hypothesis using a combination of model-based analysis to quantify the HER dimerization patterns and multi-factorial experiments where HER dimerization patterns and signaling crosstalk were rationally perturbed. We have measured the activation of HER1-3 receptors and of the sentinel signaling proteins ERK, AKT, p38, JNK, STAT3 as a function of time in a panel of human mammary epithelial (HME) cells expressing different levels of HER1-3 stimulated with various ligand combinations. Our analysis using multiple ways of clustering the activation data has confirmed that the HER receptor dimer is a better predictor of the signaling through p38, ERK and AKT pathways than the total HER receptor expression and activation levels. Targeted inhibition studies to identify the causal effects allowed us to obtain a consensus regulatory interaction model, which revealed that STAT3 occupies a central role in the crosstalk between the studied pathways.

  5. Anti-cancer effect of bee venom toxin and melittin in ovarian cancer cells through induction of death receptors and inhibition of JAK2/STAT3 pathway

    SciTech Connect

    Jo, Miran; Park, Mi Hee; Kollipara, Pushpa Saranya [College of Pharmacy and Medical Research Center, Chungbuk National University, 48, Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk, 361-763 (Korea, Republic of)] [College of Pharmacy and Medical Research Center, Chungbuk National University, 48, Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk, 361-763 (Korea, Republic of); An, Byeong Jun; Song, Ho Sueb [College of Oriental Medicine, Kyungwon University, San 65, Bokjeong-dong, Sujeong-gu, Seongnam, Gyeonggii 461-701 (Korea, Republic of)] [College of Oriental Medicine, Kyungwon University, San 65, Bokjeong-dong, Sujeong-gu, Seongnam, Gyeonggii 461-701 (Korea, Republic of); Han, Sang Bae [College of Pharmacy and Medical Research Center, Chungbuk National University, 48, Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk, 361-763 (Korea, Republic of)] [College of Pharmacy and Medical Research Center, Chungbuk National University, 48, Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk, 361-763 (Korea, Republic of); Kim, Jang Heub [Department of Obstetrics and Gynecology, College of Medicine, The Catholic University of Korea, 505, Banpo-dong, Seocho-gu, Seoul 137-040 (Korea, Republic of)] [Department of Obstetrics and Gynecology, College of Medicine, The Catholic University of Korea, 505, Banpo-dong, Seocho-gu, Seoul 137-040 (Korea, Republic of); Song, Min Jong, E-mail: bitsugar@catholic.ac.kr [Department of Obstetrics and Gynecology, College of Medicine, The Catholic University of Korea, 505, Banpo-dong, Seocho-gu, Seoul 137-040 (Korea, Republic of); Hong, Jin Tae, E-mail: jinthong@chungbuk.ac.kr [College of Pharmacy and Medical Research Center, Chungbuk National University, 48, Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk, 361-763 (Korea, Republic of)

    2012-01-01

    We investigated whether bee venom and melittin, a major component of bee venom, inhibit cell growth through enhancement of death receptor expressions in the human ovarian cancer cells, SKOV3 and PA-1. Bee venom (1–5 ?g/ml) and melittin (0.5–2 ?g/ml) inhibited the growth of SKOV3 and PA-1 ovarian cancer cells by the induction of apoptotic cell death in a dose dependent manner. Consistent with apoptotic cell death, expression of death receptor (DR) 3 and DR6 was increased in both cancer cells, but expression of DR4 was increased only in PA-1 cells. Expression of DR downstream pro-apoptotic proteins including caspase-3, 8, and Bax was concomitantly increased, but the phosphorylation of JAK2 and STAT3 and the expression of Bcl-2 were inhibited by treatment with bee venom and melittin in SKOV3 and PA-1 cells. Expression of cleaved caspase-3 was increased in SKOV3, but cleaved caspase-8 was increased in PA-1 cells. Moreover, deletion of DR3, DR4, and DR6 by small interfering RNA significantly reversed bee venom and melittin-induced cell growth inhibitory effect as well as down regulation of STAT3 by bee venom and melittin in SKOV3 and PA-1 ovarian cancer cell. These results suggest that bee venom and melittin induce apoptotic cell death in ovarian cancer cells through enhancement of DR3, DR4, and DR6 expression and inhibition of STAT3 pathway. -- Highlights: ? Some studies have showed that bee venom and/or melittin have anti-cancer effects. ? We found that bee venom and melittin inhibited cell growth in ovarian cancer cells. ? Bee venom and melittin induce apoptosis in SKOV3 and PA-1.

  6. Forced Dimerization of gp130 Leads to Constitutive STAT3 Activation, Cytokine-independent Growth, and Blockade of Differentiation of Embryonic Stem Cells

    PubMed Central

    Stuhlmann-Laeisz, Christiane; Lang, Sigrid; Chalaris, Athena; Krzysztof, Paliga; Enge, Sudarman; Eichler, Jutta; Klingmüller, Ursula; Samuel, Michael; Ernst, Matthias; Scheller, Jürgen

    2006-01-01

    The mode of activation of glycoprotein 130 kDa (gp130) and the transmission of the activation status through the plasma membrane are incompletely understood. In particular, the molecular function of the three juxtamembrane fibronectin III-like domains of gp130 in signal transmission remains unclear. To ask whether forced dimerization of gp130 is sufficient for receptor activation, we replaced the entire extracellular portion of gp130 with the c-jun leucine zipper region in the chimeric receptor protein L-gp130. On expression in cells, L-gp130 stimulates ligand-independent signal transducer and activator of transcription (STAT) 3 and extracellular signal-regulated kinase 1/2 phosphorylation. gp130 activation could be abrogated by the addition of a competing peptide comprising the leucine zipper region of c-fos. When stably expressed in the interleukin-3–dependent Ba/F3 murine pre-B-cells, these cells showed constitutive STAT3 activation and cytokine-independent growth over several months. Because gp130 stimulation completely suppressed differentiation of murine embryonic stem cells in vitro, we also stably expressed L-gp130 in these cells, which completely blocked their differentiation in the absence of cytokine stimulation and was consistent with high constitutive expression levels of the stem cell factor OCT-4. Thus, L-gp130 can be used in vitro and in vivo to mimic constitutive and ligand-independent activation of gp130 and STAT3, the latter of which is frequently observed in neoplastic diseases. PMID:16624864

  7. Forced dimerization of gp130 leads to constitutive STAT3 activation, cytokine-independent growth, and blockade of differentiation of embryonic stem cells.

    PubMed

    Stuhlmann-Laeisz, Christiane; Lang, Sigrid; Chalaris, Athena; Krzysztof, Paliga; Enge, Sudarman; Eichler, Jutta; Klingmüller, Ursula; Samuel, Michael; Ernst, Matthias; Rose-John, Stefan; Scheller, Jürgen

    2006-07-01

    The mode of activation of glycoprotein 130 kDa (gp130) and the transmission of the activation status through the plasma membrane are incompletely understood. In particular, the molecular function of the three juxtamembrane fibronectin III-like domains of gp130 in signal transmission remains unclear. To ask whether forced dimerization of gp130 is sufficient for receptor activation, we replaced the entire extracellular portion of gp130 with the c-jun leucine zipper region in the chimeric receptor protein L-gp130. On expression in cells, L-gp130 stimulates ligand-independent signal transducer and activator of transcription (STAT) 3 and extracellular signal-regulated kinase 1/2 phosphorylation. gp130 activation could be abrogated by the addition of a competing peptide comprising the leucine zipper region of c-fos. When stably expressed in the interleukin-3-dependent Ba/F3 murine pre-B-cells, these cells showed constitutive STAT3 activation and cytokine-independent growth over several months. Because gp130 stimulation completely suppressed differentiation of murine embryonic stem cells in vitro, we also stably expressed L-gp130 in these cells, which completely blocked their differentiation in the absence of cytokine stimulation and was consistent with high constitutive expression levels of the stem cell factor OCT-4. Thus, L-gp130 can be used in vitro and in vivo to mimic constitutive and ligand-independent activation of gp130 and STAT3, the latter of which is frequently observed in neoplastic diseases. PMID:16624864

  8. Peripheral nerve regeneration and NGF-dependent neurite outgrowth of adult sensory neurons converge on STAT3 phosphorylation downstream of neuropoietic cytokine receptor gp130.

    PubMed

    Quarta, Serena; Baeumer, Bastian E; Scherbakov, Nadja; Andratsch, Manfred; Rose-John, Stefan; Dechant, Georg; Bandtlow, Christine E; Kress, Michaela

    2014-09-24

    After nerve injury, adult sensory neurons can regenerate peripheral axons and reconnect with their target tissue. Initiation of outgrowth, as well as elongation of neurites over long distances, depends on the signaling of receptors for neurotrophic growth factors. Here, we investigated the importance of gp130, the signaling subunit of neuropoietic cytokine receptors in peripheral nerve regeneration. After sciatic nerve crush, functional recovery in vivo was retarded in SNS-gp130(-/-) mice, which specifically lack gp130 in sensory neurons. Correspondingly, a significantly reduced number of free nerve endings was detected in glabrous skin from SNS-gp130(-/-) compared with control mice after nerve crush. Neurite outgrowth and STAT3 activation in vitro were severely reduced in cultures in gp130-deficient cultured neurons. Surprisingly, in neurons obtained from SNS-gp130(-/-) mice the increase in neurite length was reduced not only in response to neuropoietic cytokine ligands of gp130 but also to nerve growth factor (NGF), which does not bind to gp130-containing receptors. Neurite outgrowth in the absence of neurotrophic factors was partially rescued in gp130-deficient neurons by leptin, which activates STAT3 downstream of leptic receptor and independent of gp130. The neurite outgrowth response of gp130-deficient neurons to NGF was fully restored in the presence of leptin. Based on these findings, gp130 signaling via STAT3 activation is suggested not only to be an important regulator of peripheral nerve regeneration in vitro and in vivo, but as determining factor for the growth promoting action of NGF in adult sensory neurons. PMID:25253866

  9. STAT3 transcription factor is constitutively activated and is oncogenic in nasal-type NK/T-cell lymphoma

    E-print Network

    Paris-Sud XI, Université de

    STAT3 transcription factor is constitutively activated and is oncogenic in nasal-type NK in the oncogenic process of nasal-type NK cell lymphomas, and may represent a promising therapeutical target. 3

  10. Effects of the tropical ginger compound,1’-acetoxychavicol acetate, against tumor promotion in K5.Stat3C transgenic mice

    PubMed Central

    2012-01-01

    The purpose of the current study was to determine whether a tropical ginger derived compound 1’-acetoxychavicol acetate (ACA), suppresses skin tumor promotion in K5.Stat3C mice. In a two-week study in which wild-type (WT) and K5.Stat3C mice were co-treated with either vehicle, ACA, galanga extract, or fluocinolone acetonide (FA) and tetradecanoyl phorbol acetate (TPA), only the galanga extract and FA suppressed TPA-induced skin hyperproliferation and wet weight. None of these agents were effective at suppressing p-Tyr705Stat3 expression. However, ACA and FA showed promising inhibitory effects against skin tumorigenesis in K5.Stat3C mice. ACA also suppressed phospho-p65 NF-?B activation, suggesting a potential mechanism for its action. PMID:22704648

  11. Translational profiling of cardiomyocytes identifies an early Jak1/Stat3 injury response required for zebrafish heart regeneration

    PubMed Central

    Fang, Yi; Gupta, Vikas; Karra, Ravi; Holdway, Jennifer E.; Kikuchi, Kazu; Poss, Kenneth D.

    2013-01-01

    Certain lower vertebrates like zebrafish activate proliferation of spared cardiomyocytes after cardiac injury to regenerate lost heart muscle. Here, we used translating ribosome affinity purification to profile translating RNAs in zebrafish cardiomyocytes during heart regeneration. We identified dynamic induction of several Jak1/Stat3 pathway members following trauma, events accompanied by cytokine production. Transgenic Stat3 inhibition in cardiomyocytes restricted injury-induced proliferation and regeneration, but did not reduce cardiogenesis during animal growth. The secreted protein Rln3a was induced in a Stat3-dependent manner by injury, and exogenous Rln3 delivery during Stat3 inhibition stimulated cardiomyocyte proliferation. Our results identify an injury-specific cardiomyocyte program essential for heart regeneration. PMID:23901114

  12. New Role of JAK2/STAT3 Signaling in Endothelial Cell Oxidative Stress Injury and Protective Effect of Melatonin

    PubMed Central

    Yan, Juanjuan; Liang, Zhenxin; Wang, Ning; Li, Yue; Chen, Wensheng; Yu, Shiqiang; Jin, Zhenxiao; Yi, Dinghua

    2013-01-01

    Previous studies have shown that the JAK2/STAT3 signaling pathway plays a regulatory role in cellular oxidative stress injury (OSI). In this study, we explored the role of the JAK2/STAT3 signaling pathway in hydrogen peroxide (H2O2)-induced OSI and the protective effect of melatonin against (H2O2)-induced injury in human umbilical vein endothelial cells (HUVECs). AG490 (a specific inhibitor of the JAK2/STAT3 signaling pathway) and JAK2 siRNA were used to manipulate JAK2/STAT3 activity, and the results showed that AG490 and JAK2 siRNA inhibited OSI and the levels of p-JAK2 and p-STAT3. HUVECs were then subjected to H2O2 in the absence or presence of melatonin, the main secretory product of the pineal gland. Melatonin conferred a protective effect against H2O2, which was evidenced by improvements in cell viability, adhesive ability and migratory ability, decreases in the apoptotic index and reactive oxygen species (ROS) production and several biochemical parameters in HUVECs. Immunofluorescence and Western blotting showed that H2O2 treatment increased the levels of p-JAK2, p-STAT3, Cytochrome c, Bax and Caspase3 and decreased the levels of Bcl2, whereas melatonin treatment partially reversed these effects. We, for the first time, demonstrate that the inhibition of the JAK2/STAT3 signaling pathway results in a protective effect against endothelial OSI. The protective effects of melatonin against OSI, at least partially, depend upon JAK2/STAT3 inhibition. PMID:23483946

  13. STAT3 Activation in Pressure-Overloaded Feline Myocardium: Role for Integrins and the Tyrosine Kinase BMX

    PubMed Central

    Willey, Christopher D.; Palanisamy, Arun P.; Johnston, Rebecca K.; Mani, Santhosh K.; Shiraishi, Hirokazu; Tuxworth, William J.; Zile, Michael R.; Balasubramanian, Sundaravadivel; Kuppuswamy, Dhandapani

    2008-01-01

    Growth, survival and cytoskeletal rearrangement of cardiomyocytes are critical for cardiac hypertrophy. Signal transducer and activator of transcription-3 (STAT3) activation is an important cardioprotective factor associated with cardiac hypertrophy. Although STAT3 activation has been reported via signaling through Janus Kinase 2 (JAK2) in several cardiac models of hypertrophy, the importance of other nonreceptor tyrosine kinases (NTKs) has not been explored. Utilizing an in vivo feline right ventricular pressure-overload (RVPO) model of hypertrophy, we demonstrate that in 48 h pressure-overload (PO) myocardium, STAT3 becomes phosphorylated and redistributed to detergent-insoluble fractions with no accompanying JAK2 activation. PO also caused increased levels of phosphorylated STAT3 in both cytoplasmic and nuclear fractions. To investigate the role of other NTKs, we used our established in vitro cell culture model of hypertrophy where adult feline cardiomyocytes are embedded three-dimensionally (3D) in type-I collagen and stimulated with an integrin binding peptide containing an Arg-Gly-Asp (RGD) motif that we have previously shown to recapitulate the focal adhesion complex (FAC) formation of 48 h RVPO. RGD stimulation of adult cardiomyocytes in vitro caused both STAT3 redistribution and activation that were accompanied by the activation and redistribution of c-Src and the TEC family kinase, BMX, but not JAK2. However, infection with dominant negative c-Src adenovirus was unable to block RGD-stimulated changes on either STAT3 or BMX. Further analysis in vivo in 48 h PO myocardium showed the presence of both STAT3 and BMX in the detergent-insoluble fraction with their complex formation and phosphorylation. Therefore, these studies indicate a novel mechanism of BMX-mediated STAT3 activation within a PO model of cardiac hypertrophy that might contribute to cardiomyocyte growth and survival. PMID:18612371

  14. Stimulation of the vagus nerve attenuates macrophage activation by activating the Jak2STAT3 signaling pathway

    Microsoft Academic Search

    Esmerij P van der Zanden; Frans O The; Maarten F Bijlsma; David J van Westerloo; Roelof J Bennink; Hans-Rudolf Berthoud; Satoshi Uematsu; Shizuo Akira; Rene M van den Wijngaard; Guy E Boeckxstaens; Wouter J de Jonge

    2005-01-01

    Acetylcholine released by efferent vagus nerves inhibits macrophage activation. Here we show that the anti-inflammatory action of nicotinic receptor activation in peritoneal macrophages was associated with activation of the transcription factor STAT3. STAT3 was phosphorylated by the tyrosine kinase Jak2 that was recruited to the ?7 subunit of the nicotinic acetylcholine receptor. The anti-inflammatory effect of nicotine required the ability

  15. Molecular Cell STAT3 Activation of miR-21 and miR-181b-1

    E-print Network

    Bulyk, Martha L.

    Molecular Cell Article STAT3 Activation of miR-21 and miR-181b-1 via PTEN and CYLD Are Part- moters. STAT3, a transcription factor activated by IL-6, directly activates miR-21 and miR-181b-1. Remarkably, transient expression of either microRNA induces the epigenetic switch. MiR-21 and miR-181b-1

  16. CTLA4 aptamer delivers STAT3 siRNA to tumor-associated and malignant T cells

    PubMed Central

    Herrmann, Andreas; Priceman, Saul J.; Kujawski, Maciej; Xin, Hong; Cherryholmes, Gregory A.; Zhang, Wang; Zhang, Chunyan; Lahtz, Christoph; Kowolik, Claudia; Forman, Steve J.; Kortylewski, Marcin; Yu, Hua

    2014-01-01

    Intracellular therapeutic targets that define tumor immunosuppression in both tumor cells and T cells remain intractable. Here, we have shown that administration of a covalently linked siRNA to an aptamer (apt) that selectively binds cytotoxic T lymphocyte–associated antigen 4 (CTLA4apt) allows gene silencing in exhausted CD8+ T cells and Tregs in tumors as well as CTLA4-expressing malignant T cells. CTLA4 expression was upregulated in CD8+ T cells in the tumor milieu; therefore, CTLA4apt fused to a STAT3-targeting siRNA (CTLA4apt–STAT3 siRNA) resulted in internalization into tumor-associated CD8+ T cells and silencing of STAT3, which activated tumor antigen–specific T cells in murine models. Both local and systemic administration of CTLA4apt–STAT3 siRNA dramatically reduced tumor-associated Tregs. Furthermore, CTLA4apt–STAT3 siRNA potently inhibited tumor growth and metastasis in various mouse tumor models. Importantly, CTLA4 expression is observed in T cells of patients with blood malignancies, and CTLA4apt–STAT3 siRNA treatment of immunodeficient mice bearing human T cell lymphomas promoted tumor cell apoptosis and tumor growth inhibition. These data demonstrate that a CTLA4apt-based siRNA delivery strategy allows gene silencing in both tumor-associated T cells and tumor cells and inhibits tumor growth and metastasis. PMID:24892807

  17. Downregulation of endogenous STAT3 augments tumoricidal activity of interleukin 15 activated dendritic cell against lymphoma and leukemia via TRAIL.

    PubMed

    Hira, Sumit Kumar; Mondal, Indrani; Bhattacharya, Debasis; Manna, Partha Pratim

    2014-10-01

    Effector functions in tumor resistance by dendritic cells (DCs) are less well characterized. In this study, we describe that the murine DCs upon stimulation with recombinant IL-15 in vitro or in vivo, expresses TNF superfamily member TRAIL which mediates cytotoxicity and growth inhibition against a murine lymphoma called Dalton lymphoma (DL) via apoptosis. Presence of tumor lysate or intact tumor cells significantly reduces the DC mediated tumoricidal effect, possibly via masking and down-regulating TRAIL in DCs. The antitumor effect of DC derived TRAIL was further augmented by deactivation of STAT3 in tumor cells by cucurbitacin I, which makes it more susceptible to DC derived TRAIL Treatment of tumor cells with cucurbitacin I upregulates TRAIL receptor expression in addition to activation of caspases. Compared to naïve DCs, DCs from tumor bearing mice are significantly impaired in TRAIL expression and consequent antitumor functions against DL which was partially restored by activation with IL-15 or LPS. Priming with recombinant IL-15 prolongs the survival of tumor bearing mice treated with cucurbitacin I. Naïve peripheral blood DCs derived from chronic myeloid leukemia (CML) patients have significant impairment in expression of TRAIL and consequent tumoricidal properties against TRAIL sensitive lymphoma cell lines and primary tumor cells compared to normal control. PMID:25139620

  18. Concurrent CD44s and STAT3 expression in human clear cell renal cellular carcinoma and its impact on survival.

    PubMed

    Qin, Jun; Yang, Bo; Xu, Bao-Qin; Smithc, Amber; Xu, Liang; Yuan, Jian-Lin; Li, Ling

    2014-01-01

    Although CD44 was overexpressed and considered as a useful prognostic marker in renal cell carcinoma, the prognostic role of CD44s in clear cell renal cell carcinoma (ccRCC) remains controversial. Moreover, the correlation and prognostic significance of CD44s and its downstream signaling target pSTAT3 are unclear in ccRCC. In this study, 75 pairs of carcinoma and paired adjacent non-tumor renal tissue samples were collected from patients with localized ccRCC who underwent a nephrectomy. The expression levels of CD44s and pSTAT3 were analyzed using immunohistochemistry. Correlations between CD44s/pSTAT3 expression and clinical and pathological characteristics were determined using x(2) test, Kaplan-Meier analysis and Cox's proportional hazards model. We found that CD44s is highly expressed in 46.67% of tumor tissues, and its high expression was significantly associated with high tumor grade (P < 0.001), large tumor size (P = 0.009) and advanced T stage (P = 0.004). A strong correlation exists between high expression of CD44s and pSTAT3 (r = 0.4013, P = 0.0004). The joint over expression of CD44s and pSTAT3 was present in 42.66% of tumor specimens and had an additive negative impact on overall survival. Patients with CD44s(high)pSTAT3(high) expression had significantly poor survival as compared to patients with CD44s(low)pSTAT3(low) tumor expression (P = 0.024), though the concurrent overexpression of CD44s and pSTAT3 was not an independent prognostic factor for overall survival. Our data indicate that expression of both CD44s and pSTAT3 in ccRCC is associated with advanced tumor stage and patient survival. The conclusions from this study may improve the prediction of ccRCC prognosis information when CD44s and pSTAT3 expression are evaluated together with classical clinicopathological parameters. PMID:25031744

  19. Essential role of Pin1 via STAT3 signalling and mitochondria-dependent pathways in restenosis in type 2 diabetes

    PubMed Central

    Lv, Lei; Zhang, Jiwei; Zhang, Lan; Xue, Guanhua; Wang, Peng; Meng, Qiurong; Liang, Wei

    2013-01-01

    Type 2 diabetes (T2D) is associated with accelerated restenosis rates after angioplasty. We have previously proved that Pin1 played an important role in vascular smooth muscle cell (VSMC) cycle and apoptosis. But neither the role of Pin1 in restenosis by T2D, nor the molecular mechanism of Pin1 in these processes has been elucidated. A mouse model of T2D was generated by the combination of high-fat diet (HFD) and streptozotocin (STZ) injections. Both Immunohistochemistry and Western blot revealed that Pin1 expression was up-regulated in the arterial wall in T2D mice and in VSMCs in culture conditions mimicking T2D. Next, increased activity of Pin1 was observed in neointimal hyperplasia after arterial injury in T2D mice. Further analysis confirmed that 10% serum of T2D mice and Pin1-forced expression stimulated proliferation, inhibited apoptosis, enhanced cell cycle progression and migration of VSMCs, whereas Pin1 knockdown resulted in the converse effects. We demonstrated that STAT3 signalling and mitochondria-dependent pathways played critical roles in the involvement of Pin1 in cell cycle regulation and apoptosis of VSMCs in T2D. In addition, VEGF expression was stimulated by Pin1, which unveiled part of the mechanism of Pin1 in regulating VSMC migration in T2D. Finally, the administration of juglone via pluronic gel onto injured common femoral artery resulted in a significant inhibition of the neointima/media ratio. Our findings demonstrated the vital effect of Pin1 on the VSMC proliferation, cell cycle progression, apoptosis and migration that underlie neointima formation in T2D and implicated Pin1 as a potential therapeutic target to prevent restenosis in T2D. PMID:23750710

  20. Radiation-induced senescence in securin-deficient cancer cells promotes cell invasion involving the IL-6/STAT3 and PDGF-BB/PDGFR pathways

    PubMed Central

    Yu, Yi-Chu; Yang, Pei-Ming; Chuah, Qiu-Yu; Huang, Yao-Huei; Peng, Chih-Wen; Lee, Yi-Jang; Chiu, Shu-Jun

    2013-01-01

    Securin overexpression correlates with poor prognosis in various tumours. We have previously shown that securin depletion promotes radiation-induced senescence and enhances radiosensitivity in human cancer cells. However, the underlying molecular mechanisms and the paracrine effects remain unknown. In this study, we showed that radiation induced senescence in securin-deficient human breast cancer cells involving the ATM/Chk2 and p38 pathways. Conditioned medium (CM) from senescent cells promoted the invasion and migration of non-irradiated cancer and endothelial cells. Cytokine assay analysis showed the up-regulation of various senescence-associated secretory phenotypes (SASPs). The IL-6/STAT3 signalling loop and platelet-derived growth factor-BB (PDGF-BB)/PDGF receptor (PDGFR) pathway were important for CM-induced cell migration and invasion. Furthermore, CM promoted angiogenesis in the chicken chorioallantoic membrane though the induction of IL-6/STAT3- and PDGF-BB/PDGFR-dependent endothelial cell invasion. Taken together, our results provide the molecular mechanisms for radiation-induced senescence in securin-deficient human breast cancer cells and for the SASP responses. PMID:23591770

  1. Hypothalamic nesfatin-1/NUCB2 knockdown augments hepatic gluconeogenesis that is correlated with inhibition of mTOR-STAT3 signaling pathway in rats.

    PubMed

    Wu, Dandong; Yang, Mengliu; Chen, Yang; Jia, Yanjun; Ma, Zhongmin Alex; Boden, Guenther; Li, Ling; Yang, Gangyi

    2014-04-01

    Nesfatin-1, an 82-amino acid neuropeptide, has recently been characterized as a potent metabolic regulator. However, the metabolic mechanisms and signaling steps directly associated with the action of nesfatin-1 have not been well delineated. We established a loss-of-function model of hypothalamic nesfatin-1/NUCB2 signaling in rats through an adenoviral-mediated RNA interference. With this model, we found that inhibition of central nesfatin-1/NUCB2 activity markedly increased food intake and hepatic glucose flux and decreased glucose uptake in peripheral tissue in rats fed either a normal chow diet (NCD) or a high-fat diet (HFD). The change of hepatic glucose fluxes in the hypothalamic nesfatin-1/NUCB2 knockdown rats was accompanied by increased hepatic levels of glucose-6-phosphatase and PEPCK and decreased insulin receptor, insulin receptor substrate 1, and AKT kinase phosphorylation. Furthermore, knockdown of hypothalamic nesfatin-1 led to decreased phosphorylation of mammalian target of rapamycin (mTOR) and signal transducer and activator of transcription 3 (STAT3) and the subsequent suppressor of cytokine signaling 3 levels. These results demonstrate that hypothalamic nesfatin-1/NUCB2 plays an important role in glucose homeostasis and hepatic insulin sensitivity, which is, at least in part, associated with the activation of the mTOR-STAT3 signaling pathway. PMID:24478398

  2. STAT3-dependent CXC chemokine formation and neutrophil migration in streptococcal M1 protein-induced acute lung inflammation.

    PubMed

    Zhang, Songen; Hwaiz, Rundk; Luo, Lingtao; Herwald, Heiko; Thorlacius, Henrik

    2015-06-01

    Streptococcus pyogenes cause infections ranging from mild pharyngitis to severe streptococcal toxic shock syndrome (STSS). The M1 serotype of Streptococcus pyogenes is most frequently associated with STSS. Herein, it was hypothesized that STAT3 signaling might be involved in M1 protein-evoked lung inflammation. The STAT3 inhibitor, S3I-201, was administered to male C57Bl/6 mice before iv challenge with M1 protein. Bronchoalveolar fluid and lung tissue were harvested for quantification of STAT3 activity, neutrophil recruitment, edema, and CXC chemokine formation. Neutrophil expression of Mac-1 was quantified by use of flow cytometry. Levels of IL-6 and HMGB1 were determined in plasma. CXCL2-induced neutrophil chemotaxis was studied in vitro. Administration of S3I-201 markedly reduced M1 protein-provoked STAT3 activity, neutrophil recruitment, edema formation, and inflammatory changes in the lung. In addition, M1 protein significantly increased Mac-1 expression on neutrophils and CXC chemokine levels in the lung. Treatment with S3I-201 had no effect on M1 protein-induced expression of Mac-1 on neutrophils. In contrast, inhibition of STAT3 activity greatly reduced M1 protein-induced formation of CXC chemokines in the lung. Interestingly, STAT3 inhibition markedly decreased plasma levels of IL-6 and HMGB1 in animals exposed to M1 protein. Moreover, we found that S3I-201 abolished CXCL2-induced neutrophil migration in vitro. In conclusion, these novel findings indicate that STAT3 signaling plays a key role in mediating CXC chemokine production and neutrophil infiltration in M1 protein-induced acute lung inflammation. PMID:25840996

  3. Noncanonical NF-?B activation mediates STAT3-stimulated IDO upregulation in myeloid-derived suppressor cells in breast cancer.

    PubMed

    Yu, Jinpu; Wang, Yue; Yan, Fang; Zhang, Peng; Li, Hui; Zhao, Hua; Yan, Cihui; Yan, Fan; Ren, Xiubao

    2014-09-01

    Immunotherapy for cancer treatment is achieved through the activation of competent immune effector cells and the inhibition of immunosuppressive cells, such as myeloid-derived suppressor cells (MDSCs). Although MDSCs have been shown to contribute to breast cancer development, the mechanism underlying MDSC-mediated immunosuppression is unclear. We have identified a poorly differentiated MDSC subset in breast cancer-suppressing T cell function through STAT3-dependent IDO upregulation. In this study we investigated the mechanisms underlying aberrant expression of IDO in MDSCs. MDSCs were induced by coculturing human CD33(+) myeloid progenitors with MDA-MB-231 breast cancer cells. Increased STAT3 activation in MDSCs was correlated with activation of the noncanonical NF-?B pathway, including increased NF-?B-inducing kinase (NIK) protein level, phosphorylation of cytoplasmic inhibitor of NF-?B kinase ? and p100, and RelB-p52 nuclear translocation. Blocking STAT3 activation with the small molecule inhibitor JSI-124 significantly inhibited the accumulation of NIK and IDO expression in MDSCs. Knockdown of NIK in MDSCs suppressed IDO expression but not STAT3 activation. RelB-p52 dimers were found to directly bind to the IDO promoter, leading to IDO expression in MDSCs. IL-6 was found to stimulate STAT3-dependent, NF-?B-mediated IDO upregulation in MDSCs. Furthermore, significant positive correlation between the numbers of pSTAT3(+) MDSCs, IDO(+) MDSCs, and NIK(+) MDSCs was observed in human breast cancers. These results demonstrate a STAT3/NF-?B/IDO pathway in breast cancer-derived MDSCs, which provides insight into understanding immunosuppressive mechanisms of MDSCs in breast cancer. PMID:25063873

  4. The cardioprotective effects of urocortin are mediated via activation of the Src tyrosine kinase-STAT3 pathway

    PubMed Central

    Chen-Scarabelli, Carol; Saravolatz II, Louis; Mccaukey, Roy; Scarabelli, Gabriele; Di Rezze, Justin; Mohanty, Bibhu; Barry, Sean; Latchman, David; Georgiadis, Vassilis; McCormick, James; Saravolatz, Louis; Knight, Richard; Faggian, Giuseppe; Narula, Jagat; Stephanou, Anastasis; Scarabelli, Tiziano M

    2013-01-01

    Src tyrosine kinase family was recently identified as a novel upstream modulator of MAP kinase subfamily, p42/p44, whose activation is required for urocortin (Ucn)-mediated cardioprotection. Src kinase was also shown to reduce apoptosis in different cancer cell lines, enhancing phosphorylation and DNA binding affinity of signal transducer and activator of transcription (STAT)3. In order to evaluate the effects of Ucn on the activation status of different STAT family members, HL-1 cardiac cells were incubated with Ucn (10 nM) for increasing periods of time. STAT3 was rapidly phosphorylated at Tyr705, while neither phosphorylation at Ser727 nor induction of total STAT3 was observed. Pretreatment with PP2, a selective inhibitor of Src tyrosine kinase, reduced the pSTAT?T705 phosphorylation and transcriptional activity induced by Ucn in a dose-dependent manner. Overexpression of STAT3 in HL-1 cardiac myocytes pretreated with Ucn reduced the magnitude of cell death as compared with Ucn treatment alone, while transfection of HL-1 cells with a STAT3 mutant functionally inactive, acting as a dominant negative (DN-STAT3), enhanced the extent of cell death in a dose-dependent manner. In line with this finding, in HL-1 cardiac myocytes overexpressing STAT3 treated with Ucn, addition of the Src kinase inhibitor PP2 reversed the cytoprotective effects of Ucn, proving that the cytoprotective effects of Ucn are also mediated via the Src-pSTAT?T705 phosphorylation pathway. By immunocytochemistry, Ucn induced nuclear translocation of pST3-T705, which was inhibited by pretreatment with PP2. Together, these data strongly suggest that Ucn can mediate cardioprotection by activating the Src-pSTAT-T705 phosphorylation pathway. PMID:24069562

  5. STAT3-Activating Cytokines: A Therapeutic Opportunity for Inflammatory Bowel Disease?

    PubMed Central

    Nguyen, Paul M.; Putoczki, Tracy L.

    2015-01-01

    The gastrointestinal tract is lined by a single layer of epithelial cells that secrete mucus toward the lumen, which collectively separates the immune sentinels in the underlying lamina propria from the intestinal microflora to prevent aberrant immune responses. Inflammatory bowel disease (IBD) describes a group of autoimmune diseases that arise from defects in epithelial barrier function and, as a consequence, aberrant production of inflammatory cytokines. Among these, interleukin (IL)-6, IL-11, and IL-22 are elevated in human IBD patients and corresponding mouse models and, through activation of the JAK/STAT3 pathway, can both propagate and ameliorate disease. In particular, cytokine-mediated activation of STAT3 in the epithelial lining cells affords cellular protection, survival, and proliferation, thereby affording therapeutic opportunities for the prevention and treatment of colitis. In this review, we focus on recent insights gained from therapeutic modulation of the activities of IL-6, IL-11, and IL-22 in models of IBD and advocate a cautionary approach with these cytokines to minimize their tumor-promoting activities on neoplastic epithelium. PMID:25760898

  6. HDAC8 and STAT3 repress BMF gene activity in colon cancer cells

    PubMed Central

    Kang, Y; Nian, H; Rajendran, P; Kim, E; Dashwood, W M; Pinto, J T; Boardman, L A; Thibodeau, S N; Limburg, P J; Löhr, C V; Bisson, W H; Williams, D E; Ho, E; Dashwood, R H

    2014-01-01

    Histone deacetylase (HDAC) inhibitors are undergoing clinical trials as anticancer agents, but some exhibit resistance mechanisms linked to anti-apoptotic Bcl-2 functions, such as BH3-only protein silencing. HDAC inhibitors that reactivate BH3-only family members might offer an improved therapeutic approach. We show here that a novel seleno-?-keto acid triggers global histone acetylation in human colon cancer cells and activates apoptosis in a p21-independent manner. Profiling of multiple survival factors identified a critical role for the BH3-only member Bcl-2-modifying factor (Bmf). On the corresponding BMF gene promoter, loss of HDAC8 was associated with signal transducer and activator of transcription 3 (STAT3)/specificity protein 3 (Sp3) transcription factor exchange and recruitment of p300. Treatment with a p300 inhibitor or transient overexpression of exogenous HDAC8 interfered with BMF induction, whereas RNAi-mediated silencing of STAT3 activated the target gene. This is the first report to identify a direct target gene of HDAC8 repression, namely, BMF. Interestingly, the repressive role of HDAC8 could be uncoupled from HDAC1 to trigger Bmf-mediated apoptosis. These findings have implications for the development of HDAC8-selective inhibitors as therapeutic agents, beyond the reported involvement of HDAC8 in childhood malignancy. PMID:25321483

  7. Qianliening capsule treats benign prostatic hyperplasia via suppression of the EGF/STAT3 signaling pathway

    PubMed Central

    LIN, JIUMAO; ZHOU, JIANHENG; XU, WEI; ZHONG, XIAOYONG; HONG, ZHENFENG; PENG, JUN

    2013-01-01

    Benign prostatic hyperplasia (BPH) is a pathological overgrowth of the human prostate. It may cause increased resistance to urine flow through the urethra and occasionally kidney damage, bladder stones and urinary tract infections, and therefore affect the quality of life. Qianliening capsule (QC) is a traditional Chinese formula that has been used clinically in China to treat BPH for a number of years. However, the mechanism of its anti-BPH effect remains largely unknown. We evaluated the therapeutic effect of QC in a rat model of BPH, established by the injection of testosterone following castration, and investigated the underlying molecular mechanism of action. We observed that QC treatment significantly and dose-dependently decreased the prostatic volume (PV) and prostatic index (PI; P<0.05 or P<0.01), and ameliorated the histological damage of the prostate tissue in the BPH rats. In addition, treatment with QC inhibited the phosphorylation of signal transducer and activator of transcription 3 (STAT3), as well as the expression of epidermal growth factor (EGF), epidermal growth factor receptor (EGFR), cyclin D1 and Bcl-2. Our results suggest that suppression of the EGF/STAT3 pathway may be one of the mechanisms by which QC treats BPH. PMID:23737867

  8. Notch1–STAT3–ETBR signaling axis controls reactive astrocyte proliferation after brain injury

    PubMed Central

    LeComte, Matthew D.; Shimada, Issei S.; Sherwin, Casey; Spees, Jeffrey L.

    2015-01-01

    Defining the signaling network that controls reactive astrogliosis may provide novel treatment targets for patients with diverse CNS injuries and pathologies. We report that the radial glial cell antigen RC2 identifies the majority of proliferating glial fibrillary acidic protein-positive (GFAP+) reactive astrocytes after stroke. These cells highly expressed endothelin receptor type B (ETBR) and Jagged1, a Notch1 receptor ligand. To study signaling in adult reactive astrocytes, we developed a model based on reactive astrocyte-derived neural stem cells isolated from GFAP-CreER-Notch1 conditional knockout (cKO) mice. By loss- and gain-of-function studies and promoter activity assays, we found that Jagged1/Notch1 signaling increased ETBR expression indirectly by raising the level of phosphorylated signal transducer and activator of transcription 3 (STAT3), a previously unidentified EDNRB transcriptional activator. Similar to inducible transgenic GFAP-CreER-Notch1-cKO mice, GFAP-CreER-ETBR-cKO mice exhibited a defect in reactive astrocyte proliferation after cerebral ischemia. Our results indicate that the Notch1–STAT3–ETBR axis connects a signaling network that promotes reactive astrocyte proliferation after brain injury. PMID:26124113

  9. Skin microbiome imbalance in patients with STAT1/STAT3 defects impairs innate host defense responses

    PubMed Central

    Smeekens, Sanne P.; Huttenhower, Curtis; Riza, Anca; van de Veerdonk, Frank; Zeeuwen, Patrick L.J.M.; Schalkwijk, Joost; van der Meer, Jos W.M.; Xavier, Ramnik J.; Netea, Mihai G.; Gevers, Dirk

    2014-01-01

    Background Chronic mucocutaneous candidiasis (CMC) and hyper IgE syndrome (HIES) are primary immunodeficiencies mainly caused by mutations in STAT1 and STAT3, respectively. CMC and HIES patients have an increased risk for skin and mucosal infections with fungal pathogens and Staphylococcus aureus. However, it is unknown whether the genetic defects in these patients also affect the skin and mucosal microbiome, which in turn may influence host defense mechanisms. Methods The skin and oral microbiome of CMC and HIES patients was compared to that of healthy controls at five body sites using 16S rRNA sequencing. The influence of skin colonizers on the immune response was investigated using in-vitro experiments. Results The microbiome of CMC and HIES patients contained more Gram-negative bacteria, especially Acinetobacter spp, and less of the normal Corynebacterium spp., compared to healthy controls. Exposure of human primary leukocytes to Acinetobacter suppressed the cytokine response to C. albicans and S. aureus, while the normal Corynebacteria did not suppress cytokine responses. Discussion These results demonstrate that central mediators of immune responses like STAT1 and STAT3 not only directly influence immune responses, but also result in changes of the skin microbiome that in turn can amplify the defective immune response against fungal and microbial pathogens. PMID:23796786

  10. HDAC8 and STAT3 repress BMF gene activity in colon cancer cells.

    PubMed

    Kang, Y; Nian, H; Rajendran, P; Kim, E; Dashwood, W M; Pinto, J T; Boardman, L A; Thibodeau, S N; Limburg, P J; Löhr, C V; Bisson, W H; Williams, D E; Ho, E; Dashwood, R H

    2014-01-01

    Histone deacetylase (HDAC) inhibitors are undergoing clinical trials as anticancer agents, but some exhibit resistance mechanisms linked to anti-apoptotic Bcl-2 functions, such as BH3-only protein silencing. HDAC inhibitors that reactivate BH3-only family members might offer an improved therapeutic approach. We show here that a novel seleno-?-keto acid triggers global histone acetylation in human colon cancer cells and activates apoptosis in a p21-independent manner. Profiling of multiple survival factors identified a critical role for the BH3-only member Bcl-2-modifying factor (Bmf). On the corresponding BMF gene promoter, loss of HDAC8 was associated with signal transducer and activator of transcription 3 (STAT3)/specificity protein 3 (Sp3) transcription factor exchange and recruitment of p300. Treatment with a p300 inhibitor or transient overexpression of exogenous HDAC8 interfered with BMF induction, whereas RNAi-mediated silencing of STAT3 activated the target gene. This is the first report to identify a direct target gene of HDAC8 repression, namely, BMF. Interestingly, the repressive role of HDAC8 could be uncoupled from HDAC1 to trigger Bmf-mediated apoptosis. These findings have implications for the development of HDAC8-selective inhibitors as therapeutic agents, beyond the reported involvement of HDAC8 in childhood malignancy. PMID:25321483

  11. Loss of STAT3 signaling during elevated activity causes vulnerability in hippocampal neurons

    PubMed Central

    Murase, Sachiko; Kim, Eunyoung; Lin, Lin; Hoffman, Dax A.; McKay, Ronald D.

    2012-01-01

    Chronically altered levels of network activity lead to changes in the morphology and functions of neurons. However, little is known of how changes in neuronal activity alter the intracellular signaling pathways mediating neuronal survival. Here we use primary cultures of rat hippocampal neurons to show that elevated neuronal activity impairs phosphorylation of the serine/threonine kinase, Erk1/2 and the activation of signal transducer and activator of transcription 3 (STAT3) by phosphorylation of Serine 727. Chronically stimulated neurons go through apoptosis when they fail to activate another serine/threonine kinase, Akt. Gain and loss of function experiments show that STAT3 plays the key role directly downstream from Erk1/2 as the alternative survival pathway. Elevated neuronal activity resulted in increased expression of a tumor suppressor, p53 and its target gene, Bax. These changes are observed in Kv4.2 knockout mouse hippocampal neurons, which are also sensitive to the blockade of TrkB signaling, confirming that the alteration occurs in vivo. Thus, this study provides new insight to a mechanism by which chronic elevation of activity may cause neurodegeneration. PMID:23115188

  12. VEGF drives cancer-initiating stem cells through VEGFR-2/Stat3 signaling to upregulate Myc and Sox2.

    PubMed

    Zhao, D; Pan, C; Sun, J; Gilbert, C; Drews-Elger, K; Azzam, D J; Picon-Ruiz, M; Kim, M; Ullmer, W; El-Ashry, D; Creighton, C J; Slingerland, J M

    2015-06-11

    Vascular endothelial growth factor-A (VEGF), a potent angiogenic factor, is also implicated in self-renewal in several normal tissue types. VEGF has been shown to drive malignant stem cells but mechanisms thereof and tumor types affected are not fully characterized. Here, we show VEGF promotes breast and lung cancer stem cell (CSC) self-renewal via VEGF receptor-2 (VEGFR-2)/STAT3-mediated upregulation of Myc and Sox2. VEGF increased tumor spheres and aldehyde dehydrogenase activity, both proxies for stem cell function in vitro, in triple-negative breast cancer (TNBC) lines and dissociated primary cancers, and in lung cancer lines. VEGF exposure before injection increased breast cancer-initiating cell abundance in vivo yielding increased orthotopic tumors, and increased metastasis from orthotopic primaries and following tail vein injection without further VEGF treatment. VEGF rapidly stimulated VEGFR-2/JAK2/STAT3 binding and activated STAT3 to bind MYC and SOX2 promoters and induce their expression. VEGFR-2 knockdown or inhibition abrogated VEGF-mediated STAT3 activation, MYC and SOX2 induction and sphere formation. Notably, knockdown of either STAT3, MYC or SOX2 impaired VEGF-upregulation of pSTAT3, MYC and SOX2 expression and sphere formation. Each transcription factor, once upregulated, appears to promote sustained activation of the others, creating a feed-forward loop to drive self-renewal. Thus, in addition to angiogenic effects, VEGF promotes tumor-initiating cell self-renewal through VEGFR-2/STAT3 signaling. Analysis of primary breast and lung cancers (>1300 each) showed high VEGF expression, was prognostic of poor outcome and strongly associated with STAT3 and MYC expression, supporting the link between VEGF and CSC self-renewal. High-VEGF tumors may be most likely to escape anti-angiogenics by upregulating VEGF, driving CSC self-renewal to re-populate post-treatment. Our work highlights the need to better define VEGF-driven cancer subsets and supports further investigation of combined therapeutic blockade of VEGF or VEGFR-2 and JAK2/STAT3. PMID:25151964

  13. Signal transducer and activator of transcription (STAT) 3 inhibition delays the onset of lupus nephritis in MRL/lpr mice.

    PubMed

    Edwards, Lindsay J; Mizui, Masayuki; Kyttaris, Vasileios

    2015-06-01

    The transcription factor STAT3 is overexpressed and hyperactivated in T cells from SLE patients. STAT3 plays a central role in T cell differentiation into Th17 and T follicular helper cells, two subsets that orchestrate autoimmune responses in SLE. Moreover, STAT3 is important in chemokine-mediated T cell migration. To better understand its role in SLE, we inhibited STAT3 in lupus-prone mice using the small molecule Stattic. Stattic-treated mice exhibited delayed onset of proteinuria (3weeks later than controls), and had lower levels of anti-dsDNA antibodies and inflammatory cytokines. Inhibitor treatment reduced lymphadenopathy, resulted in a 3-fold decrease in total T cell number, and a 4-fold decrease in the numbers of T follicular helper cells. In vitro experiments showed that Stattic-treated T cells exhibited decreased proliferation and a decrease in ability to migrate to CXCL12. We propose that STAT3 inhibition represents a therapeutic target in SLE, particularly lupus nephritis. PMID:25869298

  14. Targeted disruption of stat3 reveals a major role for follicular stem cells in skin tumor initiation.

    PubMed

    Kim, Dae Joon; Kataoka, Ken; Rao, Dharanija; Kiguchi, Kaoru; Cotsarelis, George; Digiovanni, John

    2009-10-01

    The initiation stage of mouse skin carcinogenesis involves the induction of mutations in keratinocyte stem cells (KSC), which confers a selective growth advantage allowing clonal expansion during tumor promotion. Targeted disruption of signal transducer and activator of transcription 3 (Stat3) in bulge region KSCs was achieved by treating K15.CrePR1 x Stat3(fl/fl) mice with RU486. Deletion of Stat3 prior to skin tumor initiation with 7,12-dimethylbenz(a)anthracene significantly increased the number of apoptotic KSCs and decreased the frequency of Ha-ras codon 61 A(182)-->T transversion mutations in this cell population compared with wild-type littermates. Targeted disruption of Stat3 in bulge region KSCs at the time of initiation also dramatically reduced the number of skin tumors (by approximately 80%) produced following promotion with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate. These results show that Stat3 is required for the survival of bulge region KSCs during tumor initiation. Furthermore, these data provide direct evidence that bulge region KSCs are the primary targets for the initiation of skin tumors in this model system. PMID:19738054

  15. JSI-124 (Cucurbitacin I) Inhibits Tumor Angiogenesis of Human Breast Cancer Through Reduction of STAT3 Phosphorylation.

    PubMed

    Qi, Jia; Xia, Ge; Huang, Cheng Rong; Wang, Jian Xia; Zhang, Jian

    2015-01-01

    Breast cancer (BC) is the most frequently diagnosed type of cancer all over the world. Angiogenesis, a physiological or pathological process characterized by the sprouting of new blood vessels from existing vessels, plays a vital role in tumor nutrition. In this work, we used JSI-124 (Cucurbitacin I), a selective JAK/STAT3 signaling pathway inhibitor, to investigate the role of STAT3 in tumor angiogenesis of a human BC cell line in vitro. JSI-124 inhibited cell viability, proliferation, adhesion, migration and tube formation of a human BC cell line MDA-MB-468. After transfection with pMXs-Stat3C, a dominant active mutant, the inhibitory effects of JSI-124 on MDA-MB-468 were abolished. Furthermore, JSI-124 reduced the phosphorylation of STAT3. These results suggested that JSI-124 inhibited tumor angiogenesis of the human BC cell line in vitro through the reduction of STAT3 phosphorylation. In addition, JSI-124 could reduce VEGF transcription and secretion, suggesting that JSI-124 is also involved in the inhibition of the VEGF autocrine loop in the tumor microenvironment. PMID:25787299

  16. Role of the IL-6-JAK1-STAT3-Oct-4 pathway in the conversion of non-stem cancer cells into cancer stem-like cells

    PubMed Central

    Kim, Seog-Young; Kang, Jin Wook; Song, Xinxin; Kim, Bo Kyoung; Yoo, Young Dong; Kwon, Yong Tae; Lee, Yong J.

    2013-01-01

    Previous studies have demonstrated that a small subset of cancer cells is capable of tumor initiation. The existence of tumor initiating cancer stem cells (CSCs) has several implications in terms of future cancer treatment and therapies. However, recently, several researchers proposed that differentiated cancer cells (non-CSCs) can convert to stem-like cells to maintain equilibrium. These results imply that removing CSCs may prompt non-CSCs in the tumor to convert into stem cells to maintain the equilibrium. Interleukin-6 (IL-6) has been found to play an important role in the inducible formation of CSCs and their dynamic equilibrium with non-stem cells. In this study, we used CSC-like human breast cancer cells and their alternate subset non-CSCs to investigate how IL-6 regulates the conversion of non-CSCs to CSCs. MDA-MB-231 and MDA-MB-453 CSC-like cells formed mammospheres well, whereas most of non-stem cells died by anoikis and only part of the remaining non-stem cells produced viable mammospheres. Similar results were observed in xenograft tumor formation. Data from cytokine array assay show that IL-6 was secreted from non-CSCs when cells were cultured in ultra-low attachment plates. IL-6 regulates CSC-associated OCT-4 gene expression through the IL-6-JAK1-STAT3 signal transduction pathway in non-CSCs. Inhibiting this pathway by treatment with anti-IL-6 antibody (1 ?g/ml) or niclosamide (0.5–2 ?M)/LLL12 (5–10 ?M) effectively prevented OCT-4 gene expression. These results suggest that the IL-6-JAK1-STAT3 signal transduction pathway plays an important role in the conversion of non-CSCs into CSCs through regulation of OCT-4 gene expression. PMID:23333246

  17. Cytostatic Effect of Epstein–Barr Virus Latent Membrane Protein1 Analyzed Using Tetracycline-Regulated Expression in B Cell Lines

    Microsoft Academic Search

    J. E. Floettmann; K. Ward; A. B. Rickinson; M. Rowe

    1996-01-01

    Tetracycline-regulated vectors were used to obtain inducible expression in stable transfected B cell lines of two Epstein–Barr virus (EBV) latent genes, LMP1 and EBNA2. The transfected genes were tightly repressed by low, nontoxic concentrations of tetracycline (?1 ?g\\/ml) and, following removal of tetracycline, were induced to levels comparable to or up to 3× that of EBV-transformed normal lymphoblastoid cell lines.

  18. Novel and recurrent STAT3 mutations in hyper-IgE syndrome patients from different ethnic groups.

    PubMed

    Jiao, Hong; Tóth, Beáta; Erdos, Melinda; Fransson, Ingegerd; Rákóczi, Eva; Balogh, István; Magyarics, Zoltán; Dérfalvi, Beáta; Csorba, Gabriella; Szaflarska, Anna; Megarbane, Andre; Akatcherian, Carlo; Dbaibo, Ghassan; Rajnavölgyi, Eva; Hammarström, Lennart; Kere, Juha; Lefranc, Gérard; Maródi, László

    2008-11-01

    We performed clinical, immunological and genetic studies of 12 hyper-IgE syndrome (HIES) patients from 4 Hungarian, 2 Lebanese, one Russian, one Polish, and one Swedish families with autosomal dominant (AD) or sporadic forms of the disease to reveal cross-ethnicity of recurrent and novel mutations in the signal transducer and activator of transcription-3 gene (STAT3). Four patients from 3 Hungarian families, and one Russian, and one Swedish patient carried the heterozygous R382W germline mutation at the DNA-binding site of STAT3. The recurrent V637M mutation affecting the SRC homology 2 (SH2) domain was detected in one Lebanese and one Polish family, and the V463del deletion located in the DNA-binding domain was unveiled in another Lebanese family. A novel H332Y mutation affecting the DNA-binding site of STAT3 in three Hungarian patients from a Gypsy family was also found. The segregation of this mutation with HIES, restriction fragment length polymorphism analysis of STAT3 from patients and controls and the negligible production upon IL-6 stimulation of monocyte chemotactic protein-1 by the patient's blood mononuclear cells suggested that the H332Y mutation was disease-causing. These data suggest, that dominant negative mutations of the DNA-binding and SH2 domains of STAT3 cause AD and sporadic cases of HIES in different ethnic groups with R382W as the predominant mutation found in 5 of the 9 families. Functional and genetic data support that the novel H332Y mutation may result in the loss of function of STAT3 and leads to the HIES phenotype. PMID:18706697

  19. In silico simulations of STAT1 and STAT3 inhibitors predict SH2 domain cross-binding specificity.

    PubMed

    Szelag, Malgorzata; Sikorski, Krzysztof; Czerwoniec, Anna; Szatkowska, Katarzyna; Wesoly, Joanna; Bluyssen, Hans A R

    2013-11-15

    Signal transducers and activators of transcription (STATs) comprise a family of transcription factors that are structurally related and which participate in signaling pathways activated by cytokines, growth factors and pathogens. Activation of STAT proteins is mediated by the highly conserved Src homology 2 (SH2) domain, which interacts with phosphotyrosine motifs for specific contacts between STATs and receptors and for STAT dimerization. By generating new models for human (h)STAT1, hSTAT2 and hSTAT3 we applied comparative in silico docking to determine SH2-binding specificity of the STAT3 inhibitor stattic, and of fludarabine (STAT1 inhibitor). Thus, we provide evidence that by primarily targeting the highly conserved phosphotyrosine (pY+0) SH2 binding pocket stattic is not a specific hSTAT3 inhibitor, but is equally effective towards hSTAT1 and hSTAT2. This was confirmed in Human Micro-vascular Endothelial Cells (HMECs) in vitro, in which stattic inhibited interferon-?-induced phosphorylation of all three STATs. Likewise, fludarabine inhibits both hSTAT1 and hSTAT3 phosphorylation, but not hSTAT2, by competing with the highly conserved pY+0 and pY-X binding sites, which are less well-preserved in hSTAT2. Moreover we observed that in HMECs in vitro fludarabine inhibits cytokine and lipopolysaccharide-induced phosphorylation of hSTAT1 and hSTAT3 but does not affect hSTAT2. Finally, multiple sequence alignment of STAT-SH2 domain sequences confirmed high conservation between hSTAT1 and hSTAT3, but not hSTAT2, with respect to stattic and fludarabine binding sites. Together our data offer a molecular basis that explains STAT cross-binding specificity of stattic and fludarabine, thereby questioning the present selection strategies of SH2 domain-based competitive small inhibitors. PMID:24211327

  20. AGER/RAGE-mediated autophagy promotes pancreatic tumorigenesis and bioenergetics through the IL6-pSTAT3 pathway.

    PubMed

    Kang, Rui; Tang, Daolin; Lotze, Michael T; Zeh, Herbert J

    2012-06-01

    Pancreatic ductal adenocarcinoma (PDA), the fourth leading cause of cancer death in the United States, is a complex disease that arises in the setting of genetic alterations (KRAS, BRCA1, SMAD4, CDKN2A/p16 (INK4a) and TP53), epigenetic perturbations (MIR155, acetylation and methylation) and epicellular events (diabetes and inflammation). We have demonstrated that the advanced glycation end product-specific receptor (AGER, also called RAGE) contributes to pancreatic tumorigenesis. Targeted ablation of AGER diminishes the amount of autophagic flux and attenuates the development of early pancreatic intraepithelial neoplasia (PanIN) lesions in a murine model of KRAS-drivien carcinogenesis. Autophagy (programmed cell survival), a metabolic process of lysosome-mediated self-digestion, promotes pancreatic cancer growth. In pancreatic tumor cell lines, AGER-mediated autophagy promotes interleukin-6 (IL6)-induced phosphorylation of signal transducer and activator of transcription 3 (pSTAT3) and mitochondrial localization of pSTAT3. Enhanced mitochondrial pSTAT3 increases the pool of available ATP and increases cellular proliferation. Moreover, we observed a positive feedback loop between activation of autophagy and the IL6-pSTAT3 pathway, perhaps different from the role of cytosolic nonphosphorylated STAT3, which has been reported to inhibit autophagy. These AGER-dependent changes were found during the earliest stages of pancreatic cancer development. These observations of inflammation and altered metabolism in PDA provide a pathological link to early precursor lesion development. Thus, AGER is an important inflammatory mediator that modulates crosstalk between prosurvival pathways, IL6-pSTAT3 and autophagy, in PDA tumor cells, and contributes to early PanIN formation. PMID:22722139

  1. The clinical relevance of the miR-197/CKS1B/STAT3-mediated PD-L1 network in chemoresistant non-small-cell lung cancer.

    PubMed

    Fujita, Yu; Yagishita, Shigehiro; Hagiwara, Keitaro; Yoshioka, Yusuke; Kosaka, Nobuyoshi; Takeshita, Fumitaka; Fujiwara, Tomohiro; Tsuta, Koji; Nokihara, Hiroshi; Tamura, Tomohide; Asamura, Hisao; Kawaishi, Makoto; Kuwano, Kazuyoshi; Ochiya, Takahiro

    2015-04-01

    Programmed cell death ligand-1 (PD-L1) has recently gained considerable attention for its role in tumor immune escape. Here, we identify a miR-197/CKS1B/STAT3-mediated PD-L1 network in chemoresistant non-small-cell lung cancer (NSCLC), independent of immunoinhibitory signals. miR-197 is downregulated in platinum-resistant NSCLC specimens, resulting in the promotion of chemoresistance, tumorigenicity, and pulmonary metastasis in vitro and in vivo. Mechanistic investigations reveal that a miR-197-mediated CKS1B/STAT3 axis exerts tumor progression regulated by various oncogenic genes (Bcl-2, c-Myc, and cyclin D1), and PD-L1 is a putative biomarker of this axis. Furthermore, we demonstrate that a miR-197 mimic sensitizes PD-L1(high) drug-resistant cells to chemotherapy. These results indicate that the biological interaction between PD-L1 and chemoresistance occurs through the microRNA regulatory cascade. More importantly, expression levels of miR-197 are inversely correlated with PD-L1 expression (n = 177; P = 0.026) and are associated with worse overall survival (P = 0.015). Our discoveries suggest that the miR-197/CKS1B/STAT3-mediated network can drive tumor PD-L1 expression as a biomarker of this cascade, and miR-197 replacement therapy may be a potential treatment strategy for chemoresistant NSCLC. PMID:25597412

  2. The Clinical Relevance of the miR-197/CKS1B/STAT3-mediated PD-L1 Network in Chemoresistant Non-small-cell Lung Cancer

    PubMed Central

    Fujita, Yu; Yagishita, Shigehiro; Hagiwara, Keitaro; Yoshioka, Yusuke; Kosaka, Nobuyoshi; Takeshita, Fumitaka; Fujiwara, Tomohiro; Tsuta, Koji; Nokihara, Hiroshi; Tamura, Tomohide; Asamura, Hisao; Kawaishi, Makoto; Kuwano, Kazuyoshi; Ochiya, Takahiro

    2015-01-01

    Programmed cell death ligand-1 (PD-L1) has recently gained considerable attention for its role in tumor immune escape. Here, we identify a miR-197/CKS1B/STAT3-mediated PD-L1 network in chemoresistant non-small-cell lung cancer (NSCLC), independent of immunoinhibitory signals. miR-197 is downregulated in platinum-resistant NSCLC specimens, resulting in the promotion of chemoresistance, tumorigenicity, and pulmonary metastasis in vitro and in vivo. Mechanistic investigations reveal that a miR-197-mediated CKS1B/STAT3 axis exerts tumor progression regulated by various oncogenic genes (Bcl-2, c-Myc, and cyclin D1), and PD-L1 is a putative biomarker of this axis. Furthermore, we demonstrate that a miR-197 mimic sensitizes PD-L1high drug-resistant cells to chemotherapy. These results indicate that the biological interaction between PD-L1 and chemoresistance occurs through the microRNA regulatory cascade. More importantly, expression levels of miR-197 are inversely correlated with PD-L1 expression (n = 177; P = 0.026) and are associated with worse overall survival (P = 0.015). Our discoveries suggest that the miR-197/CKS1B/STAT3-mediated network can drive tumor PD-L1 expression as a biomarker of this cascade, and miR-197 replacement therapy may be a potential treatment strategy for chemoresistant NSCLC. PMID:25597412

  3. Nicotine Promotes Apoptosis Resistance of Breast Cancer Cells and Enrichment of Side Population Cells with Cancer Stem Cell Like Properties via a Signaling Cascade Involving Galectin-3, ?9 Nicotinic Acetylcholine Receptor and STAT3

    PubMed Central

    Guha, Prasun; Bandyopadhyaya, Gargi; Polumuri, Swamy K.; Chumsri, Saranya; Gade, Padmaja; Kalvakolanu, Dhananjaya V.; Ahmed, Hafiz

    2014-01-01

    Nicotine, a main addictive compound in tobacco smoke, has been linked to promotion and progression of lung, head and neck, pancreatic, and breast cancers, but the detailed mechanisms of cancer progression remain elusive. Here we show that nicotine induces the expression of galectin-3 (an anti-apoptotic ?-galactoside-binding lectin) in breast cancer cell line and in primary tumors from breast cancer patients. Nicotine-induced up regulation of galectin-3 is due to an increased expression of ?9 isoform of nicotinic acetylcholine receptor (?9nAChR), which activates transcription factor STAT3 that in turn, physically binds to galectin-3 (LGALS3) promoter and induces transcription of galectin-3. Intracellular galectin-3 increased mitochondrial integrity and suppressed chemotherapeutic-induced apoptosis of breast cancer cell. Moreover, nicotine induced enrichment of side population cells with cancer stem cell-like properties was modulated by galectin-3 expression and could be significantly reduced by transient knock down of LGALS3 and its upstream signaling molecules STAT3 and ?9nAChR. Thus, galectin-3 or its upstream signaling molecule STAT3 or ?9nAChR could be a potential target to prevent nicotine-induced chemoresistance in breast cancer. PMID:24668500

  4. Anti-Fibrotic Effects of Class I HDAC Inhibitor, Mocetinostat Is Associated with IL-6/Stat3 Signaling in Ischemic Heart Failure

    PubMed Central

    Nural-Guvener, Hikmet; Zakharova, Liudmila; Feehery, Lorraine; Sljukic, Snjezana; Gaballa, Mohamed

    2015-01-01

    Background: Recent studies have linked histone deacetylases (HDAC) to remodeling of the heart and cardiac fibrosis in heart failure. However, the molecular mechanisms linking chromatin remodeling events with observed anti-fibrotic effects are unknown. Here, we investigated the molecular players involved in anti-fibrotic effects of HDAC inhibition in congestive heart failure (CHF) myocardium and cardiac fibroblasts in vivo. Methods and Results: MI was created by coronary artery occlusion. Class I HDACs were inhibited in three-week post MI rats by intraperitoneal injection of Mocetinostat (20 mg/kg/day) for duration of three weeks. Cardiac function and heart tissue were analyzed at six week post-MI. CD90+ cardiac fibroblasts were isolated from ventricles through enzymatic digestion of heart. In vivo treatment of CHF animals with Mocetinostat reduced CHF-dependent up-regulation of HDAC1 and HDAC2 in CHF myocardium, improved cardiac function and decreased scar size and total collagen amount. Moreover, expression of pro-fibrotic markers, collagen-1, fibronectin and Connective Tissue Growth Factor (CTGF) were reduced in the left ventricle (LV) of Mocetinostat-treated CHF hearts. Cardiac fibroblasts isolated from Mocetinostat-treated CHF ventricles showed a decrease in expression of collagen I and III, fibronectin and Timp1. In addition, Mocetinostat attenuated CHF-induced elevation of IL-6 levels in CHF myocardium and cardiac fibroblasts. In parallel, levels of pSTAT3 were reduced via Mocetinostat in CHF myocardium. Conclusions: Anti-fibrotic effects of Mocetinostat in CHF are associated with the IL-6/STAT3 signaling pathway. In addition, our study demonstrates in vivo regulation of cardiac fibroblasts via HDAC inhibition. PMID:25997003

  5. Interruption of macrophage-derived IL-27(p28) production by IL-10 during sepsis requires STAT3 but not SOCS3.

    PubMed

    Bosmann, Markus; Russkamp, Norman F; Strobl, Birgit; Roewe, Julian; Balouzian, Liza; Pache, Florence; Radsak, Markus P; van Rooijen, Nico; Zetoune, Firas S; Sarma, J Vidya; Núñez, Gabriel; Müller, Mathias; Murray, Peter J; Ward, Peter A

    2014-12-01

    Severe sepsis and septic shock are leading causes of morbidity and mortality worldwide. Infection-associated inflammation promotes the development and progression of adverse outcomes in sepsis. The effects of heterodimeric IL-27 (p28/EBI3) have been implicated in the natural course of sepsis, whereas the molecular mechanisms underlying the regulation of gene expression and release of IL-27 in sepsis are poorly understood. We studied the events regulating the p28 subunit of IL-27 in endotoxic shock and polymicrobial sepsis following cecal ligation and puncture. Neutralizing Abs to IL-27(p28) improved survival rates, restricted cytokine release, and reduced bacterial burden in C57BL/6 mice during sepsis. Genetic disruption of IL-27 signaling enhanced the respiratory burst of macrophages. Experiments using splenectomized mice or treatment with clodronate liposomes suggested that macrophages in the spleen may be a significant source of IL-27(p28) during sepsis. In cultures of TLR4-activated macrophages, the frequency of F4/80(+)CD11b(+)IL-27(p28)(+) cells was reduced by the addition of IL-10. IL-10 antagonized both MyD88-dependent and TRIF-dependent release of IL-27(p28). Genetic deletion of STAT3 in Tie2-Cre/STAT3flox macrophages completely interrupted the inhibition of IL-27(p28) by IL-10 after TLR4 activation. In contrast, IL-10 remained fully active to suppress IL-27(p28) with deletion of SOCS3 in Tie2-Cre/SOCS3flox macrophages. Blockade of IL-10R by Ab or genetic deficiency of IL-10 resulted in 3-5-fold higher concentrations of IL-27(p28) in endotoxic shock and polymicrobial sepsis. Our studies identify IL-10 as a critical suppressing factor for IL-27(p28) production during infection-associated inflammation. These findings may be helpful for a beneficial manipulation of adverse IL-27(p28) release during sepsis. PMID:25348624

  6. Tumour immunologyCrosstalk between cancer and immune cells: role of STAT3 in the tumour microenvironment

    Microsoft Academic Search

    Marcin Kortylewski; Drew Pardoll; Hua Yu

    2007-01-01

    Immune cells in the tumour microenvironment not only fail to mount an effective anti-tumour immune response, but also interact intimately with the transformed cells to promote oncogenesis actively. Signal transducer and activator of transcription 3 (STAT3), which is a point of convergence for numerous oncogenic signalling pathways, is constitutively activated both in tumour cells and in immune cells in the

  7. The STAT3 inhibitor WP1066 synergizes with vorinostat to induce apoptosis of mantle cell lymphoma cells.

    PubMed

    Lu, Kang; Chen, Na; Zhou, Xiang-Xiang; Ge, Xue-Ling; Feng, Li-Li; Li, Pei-Pei; Li, Xin-Yu; Geng, Ling-Yun; Wang, Xin

    2015-08-14

    Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin lymphoma (NHL) characterized by the translocation t (11; 14) (q13; q32). Drug resistance remains a formidable obstacle to treatment and the median survival for MCL patients is between 3 and 5 years. Thus, there is an urgent need to discover novel approaches to MCL therapy. The signal transducer and activation of transcription 3 (STAT3) has been found to be constitutively activated in several subtypes of MCL cell lines and MCL tumors. WP1066, a small-molecule inhibitor of STAT3, exerted antitumor activity in hematological and solid malignancies by inhibiting key survival and growth signaling pathways. In the present study, we evaluated the antiproliferative and proapoptotic activity of WP1066 combined with pan-histone deacetylase (HDAC) inhibitor vorinostat (SAHA) in a panel of MCL cell lines. In addition, potential mechanisms involved were also explored. The outcome showed that combination of WP1066 with SAHA resulted in synergistic growth inhibition and apoptosis induction in MCL cell lines in vitro. Furthermore, combination of WP1066 with SAHA inhibited the constitutive STAT3 activation and modulated mRNA expressions of anti- and pro-apoptotic genes. Our findings suggest that agents targeting the STAT3 pathway such as WP1066 may be useful therapeutic drugs for MCL when combined with SAHA. PMID:26116769

  8. STAT3-independent inhibition of lysophosphatidic acid-mediated upregulation of connective tissue growth factor (CTGF) by cucurbitacin I

    Microsoft Academic Search

    Angela Graness; Valeria Poli; Margarete Goppelt-Struebe

    2006-01-01

    Cucurbitacins are recognised as anti-tumour agents because of their interference with STAT3 signalling, but may also affect the integrity of the actin cytoskeleton. In the present study the effect of cucurbitacin I was investigated in fibroblasts. In these cells, cucurbitacin I interfered with lysophosphatidic acid (LPA) signalling. It inhibited tyrosine phosphorylation of focal adhesion proteins and induction of connective tissue

  9. Cytostatic effect of Epstein-Barr virus latent membrane protein-1 analyzed using tetracycline-regulated expression in B cell lines.

    PubMed

    Floettmann, J E; Ward, K; Rickinson, A B; Rowe, M

    1996-09-01

    Tetracycline-regulated vectors were used to obtain inducible expression in stable transfected B cell lines of two Epstein-Barr virus (EBV) latent genes, LMP1 and EBNA2. The transfected genes were tightly repressed by low, nontoxic concentrations of tetracycline (< or = 1 microgram/ml) and, following removal of tetracycline, were induced to levels comparable to or up to 3x that of EBV-transformed normal lymphoblastoid cell lines. In transfected DG75 cells, induced expression of LMP1, but not of EBNA2, led to the expected upregulation of various cell surface markers, including: CD40, CD54, CD58, and HLA class I.A novel observation was that both LMP1 and EBNA2 independently caused the downregulation of surface IgM, an effect mirrored in EBV-positive Burkitt lymphoma lines undergoing phenotypic drift during the transition from latency I to latency III in which both LMP1 and EBNA2 are upregulated. Most remarkably, induced LMP1 expression almost completely inhibited cell growth for 4 to 5 days, after which the cells recovered a limited proliferative capacity. The cytostatic effect of LMP1 was observed in all three B cell lines studied: DG75, BJAB, and Akata. Further analysis showed that induction of LMP1 coincided with a reduction in the levels of c-myc, and that the cytostatic effect was due to an accumulation of cells at the G2/M phase of the cell cycle. These data suggest a novel function for the LMP1 oncogene in controlling the proliferation of EBV-infected cells by regulating progress through G2/M phase. PMID:8806537

  10. STAT3 mutations unify the pathogenesis of chronic lymphoproliferative disorders of NK cells and T-cell large granular lymphocyte leukemia

    PubMed Central

    Jerez, Andres; Clemente, Michael J.; Makishima, Hideki; Koskela, Hanna; LeBlanc, Francis; Peng Ng, Kwok; Olson, Thomas; Przychodzen, Bartlomiej; Afable, Manuel; Gomez-Segui, Ines; Guinta, Kathryn; Durkin, Lisa; Hsi, Eric D.; McGraw, Kathy; Zhang, Dan; Wlodarski, Marcin W.; Porkka, Kimmo; Sekeres, Mikkael A.; List, Alan; Mustjoki, Satu; Loughran, Thomas P.

    2012-01-01

    Chronic lymphoproliferative disorders of natural killer cells (CLPD-NKs) and T-cell large granular lymphocytic leukemias (T-LGLs) are clonal lymphoproliferations arising from either natural killer cells or cytotoxic T lymphocytes (CTLs). We have investigated for distribution and functional significance of mutations in 50 CLPD-NKs and 120 T-LGL patients by direct sequencing, allele-specific PCR, and microarray analysis. STAT3 gene mutations are present in both T and NK diseases: approximately one-third of patients with each type of disorder convey these mutations. Mutations were found in exons 21 and 20, encoding the Src homology 2 domain. Patients with mutations are characterized by symptomatic disease (75%), history of multiple treatments, and a specific pattern of STAT3 activation and gene deregulation, including increased expression of genes activated by STAT3. Many of these features are also found in patients with wild-type STAT3, indicating that other mechanisms of STAT3 activation can be operative in these chronic lymphoproliferative disorders. Treatment with STAT3 inhibitors, both in wild-type and mutant cases, resulted in accelerated apoptosis. STAT3 mutations are frequent in large granular lymphocytes suggesting a similar molecular dysregulation in malignant chronic expansions of NK and CTL origin. STAT3 mutations may distinguish truly malignant lymphoproliferations involving T and NK cells from reactive expansions. PMID:22859607

  11. Arctigenin promotes apoptosis in ovarian cancer cells via the iNOS/NO/STAT3/survivin signalling.

    PubMed

    Huang, Ke; Li, Li-an; Meng, Yuan-guang; You, Yan-qin; Fu, Xiao-yu; Song, Lei

    2014-12-01

    Arctigenin is a biologically active lignan extracted from the seeds of Arctium lappa and shows anticancer activity against a variety of human cancers. The aim of this study was to determine the effects of arctigenin on ovarian cancer cell proliferation and survival and associated molecular mechanisms. Human ovarian cancer OVCAR3 and SKOV3 cells were treated with arctigenin, and cell proliferation and apoptosis were assessed. Western blot analysis was used to examine signal transducer and activator of transcription-3 (STAT3) phosphorylation and survivin and inducible nitric oxide synthase (iNOS) expression. The involvement of STAT3/survivin/iNOS/NO signalling in arctigenin action was checked. Arctigenin treatment resulted in a significant and dose-dependent inhibition of cell proliferation. Arctigenin-treated cells showed a 4-6 times increase in the percentage of apoptosis, compared with control cells. Pre-treatment with Ac-DEVD-CHO, a specific inhibitor of caspase-3, counteracted the induction of apoptosis by arctigenin. Arctigenin treatment significantly inhibited STAT3 phosphorylation and survivin and iNOS expression. Arctigenin-induced apoptosis was impaired by pre-transfection with survivin-expressing plasmid or addition of chemical nitric oxide (NO) donors. Additionally, exogenous NO prevented the suppression of STAT3 phosphorylation and survivin expression by arctigenin. Arctigenin treatment inhibits the proliferation and induces caspase-3-dependent apoptosis of ovarian cancer cells. Suppression of iNOS/NO/STAT3/survivin signalling is causally linked to the anticancer activity of arctigenin. Therefore, arctigenin may be applicable to anticancer therapy for ovarian cancer. PMID:24842412

  12. HO-3867, a curcumin analog, sensitizes cisplatin-resistant ovarian carcinoma, leading to therapeutic synergy through STAT3 inhibition.

    PubMed

    Selvendiran, Karuppaiyah; Ahmed, Shabnam; Dayton, Alex; Kuppusamy, M Lakshmi; Rivera, Brian K; Kálai, Tamás; Hideg, Kálmán; Kuppusamy, Periannan

    2011-11-01

    Cisplatin resistance is a major obstacle in the treatment of ovarian cancer. Drug combinations with synergistic or complementary functions are a promising strategy to overcome this issue. We studied the anticancer efficacy of a novel compound, HO-3867, used in combination with cisplatin against chemotherapy-resistant ovarian cancer. A2780R cells, a cisplatin-resistant human ovarian cancer cell line, were exposed to 1, 5, or 10 uM of HO-3867 alone or in combination with cisplatin (10 ug/ml) for 24 hours. Cell viability (MTT), proliferation (BrdU), cell-cycle analysis (FACS), and protein expression (western blot) were used for in vitro studies. STAT3 overexpression was performed using transfected STAT3 cDNA. In vivo studies used cisplatin-resistant xenograft tumors grown in nude mice and treated with 100-ppm HO-3867 and weekly injections of 4-mg/kg cisplatin. HO-3867/cisplatin combination treatment significantly inhibited cisplatin-resistant cell proliferation in a concentration-dependent manner. The inhibition was associated with increased expression of p53 and p21, and decreased expression of cdk5 and cyclin D1. Apoptosis was induced by activation of Bax, cytochrome c release, and stimulated cleavage of caspase-9, caspase-3, and PARP. Overexpression of STAT3 decreased the HO-3867-induced apoptosis. The combination treatment significantly inhibited the growth of cisplatin-resistant xenograft tumors with significant downregulation of pSTAT3, and without apparent toxicity to healthy tissues. The combination treatment exhibited synergistic anticancer efficacy, which appears largely due to HO-3867-induced downregulation of pSTAT3. The results, combined with the previously-reported safety features of HO-3867, suggest the potential use of this compound as a safe and effective adjuvant for the treatment of ovarian cancer. PMID:21885917

  13. Inhibition of stat3 activation suppresses caspase-3 and the ubiquitin-proteasome system, leading to preservation of muscle mass in cancer cachexia.

    PubMed

    Silva, Kleiton Augusto Santos; Dong, Jiangling; Dong, Yanjun; Dong, Yanlan; Schor, Nestor; Tweardy, David J; Zhang, Liping; Mitch, William E

    2015-04-24

    Cachexia occurs in patients with advanced cancers. Despite the adverse clinical impact of cancer-induced muscle wasting, pathways causing cachexia are controversial, and clinically reliable therapies are not available. A trigger of muscle protein loss is the Jak/Stat pathway, and indeed, we found that conditioned medium from C26 colon carcinoma (C26) or Lewis lung carcinoma cells activates Stat3 (p-Stat3) in C2C12 myotubes. We identified two proteolytic pathways that are activated in muscle by p-Stat3; one is activation of caspase-3, and the other is p-Stat3 to myostatin, MAFbx/Atrogin-1, and MuRF-1 via CAAT/enhancer-binding protein ? (C/EBP?). Using sequential deletions of the caspase-3 promoter and CHIP assays, we determined that Stat3 activation increases caspase-3 expression in C2C12 cells. Caspase-3 expression and proteolytic activity were stimulated by p-Stat3 in muscles of tumor-bearing mice. In mice with cachexia caused by Lewis lung carcinoma or C26 tumors, knock-out of p-Stat3 in muscle or with a small chemical inhibitor of p-Stat3 suppressed muscle mass losses, improved protein synthesis and degradation in muscle, and increased body weight and grip strength. Activation of p-Stat3 stimulates a pathway from C/EBP? to myostatin and expression of MAFbx/Atrogin-1 and increases the ubiquitin-proteasome system. Indeed, C/EBP? KO decreases the expression of MAFbx/Atrogin-1 and myostatin, while increasing muscle mass and grip strength. In conclusion, cancer stimulates p-Stat3 in muscle, activating protein loss by stimulating caspase-3, myostatin, and the ubiquitin-proteasome system. These results could lead to novel strategies for preventing cancer-induced muscle wasting. PMID:25787076

  14. A shift from pStat6 to pStat3 predominance is associated with inflammatory bowel disease-associated dysplasia

    PubMed Central

    Wick, Elizabeth C.; LeBlanc, Robert E.; Ortega, Guillermo; Robinson, Chelsea; Platz, Elizabeth; Pardoll, Drew M.; Iacobuzio-Donahue, Chris; Sears, Cynthia L.

    2011-01-01

    Background Activated Stat3 is an important mediator of oncogenesis in the colon. To test the hypothesis that select Stat activation and/or the pattern of Stat activation serves as a marker for early neoplastic transformation, we examined the distribution of activated Stat1(pStat1), Stat6(pStat6) and Stat3(pStat3) in colitis along the continuum of inactive disease to colitis-associated cancer. Methods Tissue microarrays were constructed using colonoscopy biopsy and surgical specimens from 67 patients with ulcerative colitis or Crohn’s colitis and 11 controls. 111 sets of samples were analyzed representing normal tissue, active disease, low-grade dysplasia, high-grade dysplasia, and colitis-associated cancer. Immunohistochemistry to detect pStat1, pStat6 and pStat3 in colonic epithelial and mucosal immune cells was then correlated with clinical and pathological data (tumor location, histologic type, grade and lymph node involvement). Results In 50% of colitis-associated cancer samples, pStat3 was detected prominently in epithelial cells, where it was routinely associated with intense pStat3 staining in surrounding immune cells. Stat3 activation was greater in low-grade tumors than in high-grade ones (P<0.05). pStat6 expression was more common in normal tissues than in colitis-associated cancer (P<0.05). pStat1 was detected in a small subset of immune cells in patients with chronic inactive and active colitis, low and high grade dysplasia, but not in colitis-associated cancer. Conclusions pStat3 may be a marker for neoplastic transformation in patients with colitis. A shift from predominant immune cell Stat6 activation to Stat3 activation accompanies the onset of dysplasia with concomitant increased epithelial cell Stat3 activation in a subset of patients. PMID:22021169

  15. Distinct Behaviour of Sorafenib in Experimental Cachexia-Inducing Tumours: The Role of STAT3

    PubMed Central

    Busquets, Sílvia; López-Soriano, Francisco J.; Argilés, Josep M.

    2014-01-01

    The presence of a tumour is very often associated with wasting in the host, affecting both skeletal muscle and adipose tissue. In the present study we used sorafenib, a multi-kinase inhibitor with anti-tumour activity, in order to investigate the effects of chemotherapy on wasting. Three different experimental mouse tumour models were included: C26 colon carcinoma, B16 melanoma and Lewis lung carcinoma (LLC). The results obtained clearly show that sorafenib was effective in reducing tumour growth in LLC and B16 models, while it had no effect on C26. Interestingly, sorafenib treatment reduced the signs of muscle wasting and improved the physical activity in the LLC model and also in the C26, despite the absence of antineoplastic action in the latter. Our results discard a role for IL-6 in the action of sorafenib since the drug did not affect the levels of this cytokine. Conversely, sorafenib seems to act by influencing both STAT3 and ERK activity at muscle level, leading to reduced accumulation of Pax7 and atrogin-1. Sorafenib may interfere with muscle wasting by decreasing the activation of these signal transduction pathways. PMID:25436606

  16. Oncostatin M activates STAT3 to promote endometrial cancer invasion and angiogenesis.

    PubMed

    Zhu, Minjiao; Che, Qi; Liao, Yun; Wang, Huihui; Wang, Jingyun; Chen, Zheng; Wang, Fangyuan; Dai, Chenjun; Wan, Xiaoping

    2015-07-01

    Oncostatin M (OSM), a pleiotropic cytokine, can either promote or inhibit the growth of tumors derived from specific tissues. However, little is known about the activity and expression pattern of OSM in endometrial cancers (ECs). Herein we show that expression of OSM in human ECs was significantly higher than that in hyperplastic or normal tissues. In EC tissues, high OSM levels were positively correlated with tumor stage, histological grade, myometrial invasion, and lymph node metastasis. Additionally, we demonstrated that recombinant human OSM (rhOSM) promoted tumor angiogenesis in EC cell lines by activating STAT3 (signal transducer and activator of transcription 3) and enhanced both cell migration and cell invasion. rhOSM did not, however, influence the proliferation of EC cells in vitro. In contrast, in our in vivo xenograft model, overexpression of rhOSM promoted cell proliferation, tumor growth, and angiogenesis in nude mice. Collectively, these experiments suggest that OSM may be a tumor promoter that encourages EC progression. OSM may thus serve as a potential target of antiangiogenic therapy for endometrial cancer. PMID:25954856

  17. Cisplatin-selected resistance is associated with increased motility and stem-like properties via activation of STAT3/Snail axis in atypical teratoid/rhabdoid tumor cells

    PubMed Central

    Liu, Wei-Hsiu; Wang, Mong-Lien; Chiou, Guang-Yuh; Chien, Chian-Shiu; Huang, Pin-I; Chen, Yi-Wei; Huang, Ming-Chao; Chiou, Shih-Hwa; Shih, Yang-Hsin; Ma, Hsin-I

    2015-01-01

    Atypical teratoid/rhabdoid tumor (ATRT) is a malignant pediatric brain tumor with great recurrence after complete surgery and chemotherapy. Here, we demonstrate that cisplatin treatment selects not only for resistance but also for a more oncogenic phenotype characterized by high self-renewal and invasive capabilities. These phenomena are likely due to STAT3 upregulatoin which occurred simultaneously with higher expression of Snail, an activator of epithelial–mesenchymal transition (EMT), in ATRT-CisR cells. STAT3 knockdown effectively suppressed Snail expression and blocked motility and invasion in ATRT-CisR cells, while overexpressing Snail reversed these effects. Chromatin immunoprecipitation assay indicated that STAT3 directly bound to Snail promoter. Moreover, STAT3 knockdown effectively suppressed cancer stem-like properties, synergistically enhanced the chemotherapeutic effect, and significantly improved survival rate in ATRT-CisR-transplanted immunocompromised mice. Finally, immunohistochemistrical analysis showed that STAT3 and Snail were coexpressed at high levels in recurrent ATRT tissues. Thus, the STAT3/Snail pathway plays an important role in oncogenic resistance, rendering cells not only drug-resistant but also increasingly oncogenic (invasion, EMT and recurrence). Therefore, the STAT3/Snail could be a target for ATRT treatment. PMID:25638155

  18. Astaxanthin inhibits JAK/STAT-3 signaling to abrogate cell proliferation, invasion and angiogenesis in a hamster model of oral cancer.

    PubMed

    Kowshik, J; Baba, Abdul Basit; Giri, Hemant; Deepak Reddy, G; Dixit, Madhulika; Nagini, Siddavaram

    2014-01-01

    Identifying agents that inhibit STAT-3, a cytosolic transcription factor involved in the activation of various genes implicated in tumour progression is a promising strategy for cancer chemoprevention. In the present study, we investigated the effect of dietary astaxanthin on JAK-2/STAT-3 signaling in the 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis model by examining the mRNA and protein expression of JAK/STAT-3 and its target genes. Quantitative RT-PCR, immunoblotting and immunohistochemical analyses revealed that astaxanthin supplementation inhibits key events in JAK/STAT signaling especially STAT-3 phosphorylation and subsequent nuclear translocation of STAT-3. Furthermore, astaxanthin downregulated the expression of STAT-3 target genes involved in cell proliferation, invasion and angiogenesis, and reduced microvascular density, thereby preventing tumour progression. Molecular docking analysis confirmed inhibitory effects of astaxanthin on STAT signaling and angiogenesis. Cell culture experiments with the endothelial cell line ECV304 substantiated the role of astaxanthin in suppressing angiogenesis. Taken together, our data provide substantial evidence that dietary astaxanthin prevents the development and progression of HBP carcinomas through the inhibition of JAK-2/STAT-3 signaling and its downstream events. Thus, astaxanthin that functions as a potent inhibitor of tumour development and progression by targeting JAK/STAT signaling may be an ideal candidate for cancer chemoprevention. PMID:25296162

  19. Cisplatin-selected resistance is associated with increased motility and stem-like properties via activation of STAT3/Snail axis in atypical teratoid/rhabdoid tumor cells.

    PubMed

    Liu, Wei-Hsiu; Chen, Ming-Teh; Wang, Mong-Lien; Lee, Yi-Yen; Chiou, Guang-Yuh; Chien, Chian-Shiu; Huang, Pin-I; Chen, Yi-Wei; Huang, Ming-Chao; Chiou, Shih-Hwa; Shih, Yang-Hsin; Ma, Hsin-I

    2015-01-30

    Atypical teratoid/rhabdoid tumor (ATRT) is a malignant pediatric brain tumor with great recurrence after complete surgery and chemotherapy. Here, we demonstrate that cisplatin treatment selects not only for resistance but also for a more oncogenic phenotype characterized by high self-renewal and invasive capabilities. These phenomena are likely due to STAT3 upregulatoin which occurred simultaneously with higher expression of Snail, an activator of epithelial-mesenchymal transition (EMT), in ATRT-CisR cells. STAT3 knockdown effectively suppressed Snail expression and blocked motility and invasion in ATRT-CisR cells, while overexpressing Snail reversed these effects. Chromatin immunoprecipitation assay indicated that STAT3 directly bound to Snail promoter. Moreover, STAT3 knockdown effectively suppressed cancer stem-like properties, synergistically enhanced the chemotherapeutic effect, and significantly improved survival rate in ATRT-CisR-transplanted immunocompromised mice. Finally, immunohistochemistrical analysis showed that STAT3 and Snail were coexpressed at high levels in recurrent ATRT tissues. Thus, the STAT3/Snail pathway plays an important role in oncogenic resistance, rendering cells not only drug-resistant but also increasingly oncogenic (invasion, EMT and recurrence). Therefore, the STAT3/Snail could be a target for ATRT treatment. PMID:25638155

  20. Embelin Reduces Systemic Inflammation and Ameliorates Organ Injuries in Septic Rats Through Downregulating STAT3 and NF-?B Pathways.

    PubMed

    Zhou, Xian-Long; Huang, Lei; Cao, Jun

    2015-08-01

    Current evidence shows that the majority of the damage induced during sepsis is pursuant to induction and overproduction of endogenous cytokines. Embelin has been reported to suppress cytokine expressions in inflammatory disorders. The present study was designed to investigate the effects of embelin on cecal and ligation and puncture (CLP)-induced rat sepsis. Single-dose administration of embelin 1 h after surgery significantly improved survival of rats with CLP-induced sepsis. In addition, embelin treatment reduced the serum levels of pro-inflammatory cytokines including tumor necrosis factor (TNF)-?, interleukin (IL)-1?, and IL-6 and decreased organ inflammation and injuries. Moreover, embelin suppressed the activation of p65 subunit of nuclear factor-kappa B (NF-?B) and signal transducers and activators of transcription 3 (STAT3). Collectively, these results indicated that embelin ameliorates sepsis in rats through suppressing STAT3 and NF-?B pathways. PMID:25682469

  1. Blocking c-myc and stat3 by E. coli expressed and enzyme digested siRNA in mouse melanoma

    SciTech Connect

    Hong Jie [Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai 200433 (China); Zhao Yingchun [Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai 200433 (China); Huang Weida [Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai 200433 (China)]. E-mail: whuang@fudan.edu.cn

    2006-09-22

    Tumour cells often show alteration in the signal-transduction pathways, leading to proliferation in response to external signals. Oncogene overexpression and constitutive expression is a common phenomenon in the development and progression of many human cancers. Therefore oncogenes provide potential targets for cancer therapy. RNA interference (RNAi), mediated by small interfering RNA (siRNA), silences genes with a high degree of specificity and potentially represents a general approach for molecularly targeted anti-cancer therapy. The data presented in this report evaluated the method of systemically administering combined esiRNAs to multiple targets as compared with the method of using a single kind of esiRNA to a single target. Our experimental data revealed that the mixed treatment of esiC-MYC and esiSTAT3 had a better inhibition effect than the single treatment of esiC-MYC or esiSTAT3 on mouse B16 melanoma.

  2. Dihydroxypentamethoxyflavone Down-Regulates Constitutive and Inducible Signal Transducers and Activators of Transcription-3 through the Induction of Tyrosine Phosphatase SHP-1

    PubMed Central

    Phromnoi, Kanokkarn; Prasad, Sahdeo; Gupta, Subash C.; Kannappan, Ramaswamy; Reuter, Simone; Limtrakul, Pornngarm

    2011-01-01

    Because constitutive activation of signal transducers and activators of transcription-3 (STAT3) has been linked with cellular transformation, survival, proliferation, chemoresistance, and angiogenesis of various tumor cells, agents that can suppress STAT3 activation have potential as cancer therapeutics. In the present report, we identified a flavone from the leaves of a Thai plant, Gardenia obtusifolia, 5,3?-dihydroxy-3,6,7,8,4?-pentamethoxyflavone (PMF), that has the ability to inhibit STAT3 activation. PMF inhibited both constitutive and interleukin-6-inducible STAT3 activation in multiple myeloma (MM) cells, as indicated by suppression of STAT3 phosphorylation, nuclear translocation, DNA binding, and STAT3-regulated gene expression. The inhibition of STAT3 by PMF was reversible. We found that the activation of various kinases including Janus-like kinase (JAK)-1, JAK-2, c-Src, extracellular signal-regulated kinases 1 and 2, AKT, and epidermal growth factor receptor, implicated in STAT3 activation, were inhibited by the flavone. It is noteworthy that pervanadate suppressed the ability of PMF to inhibit the phosphorylation of STAT3, suggesting that protein tyrosine phosphatase was involved. PMF induced the expression of SHP-1 and was linked to the dephosphorylation of STAT3, because its deletion by small interfering RNA abolished the PMF-induced constitutive and inducible STAT3 inhibition. STAT3 inhibition led to the suppression of proteins involved in proliferation (cyclin D1 and c-myc), survival (survivin, Mcl-1, Bcl-xL, Bcl-2, and cIAP-2), and angiogenesis (vascular endothelial growth factor). Finally, PMF inhibited proliferation and induced apoptosis of MM cells. PMF also significantly potentiated the apoptotic effects of Velcade and thalidomide in MM cells. Overall, these results suggest that PMF is a novel blocker of STAT3 activation and thus may have potential in suppression of tumor cell proliferation and reversal of chemoresistance in MM cells. PMID:21816954

  3. Inhibition of STAT3 and ErbB2 Suppresses Tumor Growth, Enhances Radiosensitivity, and Induces Mitochondria-Dependent Apoptosis in Glioma Cells

    SciTech Connect

    Gao Ling; Li Fengsheng; Dong Bo; Zhang Junquan; Rao Yalan; Cong Yue; Mao Bingzhi [Department of Experimental Therapy of ARS, Beijing Institute of Radiation Medicine, Beijing (China); Chen Xiaohua, E-mail: chenxh@nic.bmi.ac.c [Department of Experimental Therapy of ARS, Beijing Institute of Radiation Medicine, Beijing (China)

    2010-07-15

    Purpose: Constitutively activated signal transducer and activator of transcription 3 (STAT3) and ErbB2 are involved in the pathogenesis of many tumors, including astrocytoma. Inactivation of these molecules is reported to result in radiosensitization. The purpose of this study was to investigate whether inhibition of STAT3, ErbB2, or both could enhance radiotherapy in the human glioma model (U251 and U87 cell lines). Methods and Materials: The RNAi plasmids targeting STAT3 or ErbB2 were constructed, and their downregulatory effects on target proteins were examined by immunoblotting. After combination treatment of RNAi with or without irradiation, the cell viability was determined using 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and clonogenic assays. The in vivo effect of combined treatment was determined using the U251 xenograft model. The apoptosis caused by the inhibition of STAT3 and ErbB2 was detected, and the mechanism involved in the apoptosis was investigated, including increases in caspase proteins, mitochondrial damage, and the expression of key modulating protein of different apoptosis pathways. Results: Transfection of U251 cells with STAT3 or ErbB2 siRNA plasmids specifically reduced their target gene expressions. Inhibition of STAT3 or ErbB2 greatly decreased glioma cell survival after 2, 4, or 6 Gy irradiation. Inhibition of STAT3 and ErbB2 also enhanced radiation-induced tumor growth inhibition in the U251 xenograft model. Furthermore, the suppression of either STAT3 or ErbB2 could induce U251 cell apoptosis, which was related primarily to the mitochondrial apoptotic pathway. Conclusions: These results indicated that simultaneous inhibition of STAT3 and ErbB2 expression can promote potent antitumor activity and radiosensitizing activity in human glioma.

  4. Prognostic Role of Phospho-STAT3 in Patients with Cancers of the Digestive System: A Systematic Review and Meta-Analysis

    PubMed Central

    Huang, Zhen; Zhao, Jian-jun; Han, Yue; Li, Zhi-yu; Zhang, Ye-fan; Li, Yuan; Chen, Xiao; Hu, Xu-hui; Zhao, Hong; Cai, Jian-qiang

    2015-01-01

    Objective The definite prognostic role of p-STAT3 has not been well defined. We performed a meta-analysis evaluating the prognostic role of p-STAT3 expression in patients with digestive system cancers. Methods We searched the available articles reporting the prognostic value of p-STAT3 in patients with cancers of the digestive system, mainly including colorectal cancer, gastric cancer, hepatocellular carcinoma, esophagus cancer and pancreatic cancer. The pooled hazard ratios (HRs) with 95 % confidence intervals (95 % CIs) of overall survival (OS) and disease-free survival (DFS) were used to assess the prognostic role of p-STAT3 expression level in cancer tissues. And the association between p-STAT3 expression and clinicopathological characteristics was evaluated. Results A total of 22 studies with 3585 patients were finally enrolled in the meta-analysis. The results showed that elevated p-STAT3 expression level predicted inferior OS (HR=1.809, 95% CI: 1.442-2.270, P<0.001) and DFS (HR=1.481, 95% CI: 1.028-2.133, P= 0.035) in patients with malignant cancers of the digestive system. Increased expression of p-STAT3 is significantly related with tumor cell differentiation (Odds ratio (OR) =1.895, 95% CI: 1.364-2.632, P<0.001) and lymph node metastases (OR=2.108, 95% CI: 1.104-4.024, P=0.024). Sensitivity analysis suggested that the pooled HR was stable and omitting a single study did not change the significance of the pooled HR. Funnel plots and Egger’s tests revealed there was no significant publication bias in the meta-analysis. Conclusion Phospho-STAT3 might be a prognostic factor of patients with digestive system cancers. More well designed studies with adequate follow-up are needed to gain a thorough understanding of the prognostic role of p-STAT3. PMID:26024373

  5. Mitochondrially Associated Hepatitis B Virus X Protein Constitutively Activates Transcription Factors STAT-3 and NF-?B via Oxidative Stress

    PubMed Central

    Waris, Gulam; Huh, Kyung-Won; Siddiqui, Aleem

    2001-01-01

    The hepatitis B virus X protein (HBx) plays essential roles in viral replication and the generation of hepatocellular carcinoma. In spite of a large number of suggestive cellular targets and functions, a clear picture of its mechanism(s) of action has remained elusive. In this report, we continue to characterize its recently described mitochondrial association and further examine its impact on mitochondrial functions. HBx was previously shown to bind to a voltage-dependent anion channel (VDAC3) and alter the mitochondrial transmembrane potential (??m). Here we show that, as a consequence of association with mitochondria, HBx constitutively induces activation of transcription factors, which include STAT-3 and NF-?B. This induction of activation was sensitive to the antioxidants N-acetyl l-cysteine and pyrrolidine dithiocarbamate, as well as to overexpression of Mn-superoxide dismutase. These results therefore implicate a potential role of reactive oxygen species (ROS) in a process that ultimately leads to the activation of STAT-3 and NF-?B. Evidence is also presented for the HBx-induced generation of ROS. The ability of HBx to induce the activation of STAT-3 and NF-?B was demonstrated by mobility shift and reporter gene expression assays with lysates from HBx-transfected HepG2 cells. A C-terminal HBx deletion mutant, HBx?99, failed to bind VDAC3 and activate STAT-3 and NF-?B. These studies shed new light on the physiological significance of HBx's mitochondrial association and its role in inducing oxidative stress which can contribute to the liver disease pathogenesis associated with the hepatitis B virus infection. PMID:11604508

  6. A novel phosphorylated STAT3 inhibitor enhances T cell cytotoxicity against melanoma through inhibition of regulatory T cells

    Microsoft Academic Search

    Ling-Yuan Kong; Jun Wei; Amit K. Sharma; Jason Barr; Mohamed K. Abou-Ghazal; Izabela Fokt; Jeffrey Weinberg; Ganesh Rao; Elizabeth Grimm; Waldemar Priebe; Amy B. Heimberger

    2009-01-01

    The activation of signal transducer and activator of transcription 3 (STAT3) has been identified as a key mediator that drives\\u000a the fundamental components of melanoma malignancy, including immune suppression in melanoma patients. Increasing evidence\\u000a also suggests that regulatory T cells (Tregs) are important in suppressing anti-tumor immunity and play a dominant role in\\u000a negating efficacious immunotherapy approaches. We hypothesized that

  7. Dietary Iron Enhances Colonic Inflammation and IL-6/IL-11-Stat3 Signaling Promoting Colonic Tumor Development in Mice

    PubMed Central

    Ho, Desiree S.; Fu, S. Kristine; Forrest, Cynthia H.; Croft, Kevin D.; Olynyk, John K.; Lawrance, Ian C.; Trinder, Debbie

    2013-01-01

    Chronic intestinal inflammation and high dietary iron are associated with colorectal cancer development. The role of Stat3 activation in iron-induced colonic inflammation and tumorigenesis was investigated in a mouse model of inflammation-associated colorectal cancer. Mice, fed either an iron-supplemented or control diet, were treated with azoxymethane and dextran sodium sulfate (DSS). Intestinal inflammation and tumor development were assessed by endoscopy and histology, gene expression by real-time PCR, Stat3 phosphorylation by immunoblot, cytokines by ELISA and apoptosis by TUNEL assay. Colonic inflammation was more severe in mice fed an iron-supplemented compared with a control diet one week post-DSS treatment, with enhanced colonic IL-6 and IL-11 release and Stat3 phosphorylation. Both IL-6 and ferritin, the iron storage protein, co-localized with macrophages suggesting iron may act directly on IL-6 producing-macrophages. Iron increased DSS-induced colonic epithelial cell proliferation and apoptosis consistent with enhanced mucosal damage. DSS-treated mice developed anemia that was not alleviated by dietary iron supplementation. Six weeks post-DSS treatment, iron-supplemented mice developed more and larger colonic tumors compared with control mice. Intratumoral IL-6 and IL-11 expression increased in DSS-treated mice and IL-6, and possibly IL-11, were enhanced by dietary iron. Gene expression of iron importers, divalent metal transporter 1 and transferrin receptor 1, increased and iron exporter, ferroportin, decreased in colonic tumors suggesting increased iron uptake. Dietary iron and colonic inflammation synergistically activated colonic IL-6/IL-11-Stat3 signaling promoting tumorigenesis. Oral iron therapy may be detrimental in inflammatory bowel disease since it may exacerbate colonic inflammation and increase colorectal cancer risk. PMID:24223168

  8. Active Stat3 is required for survival of human squamous cell carcinoma cells in serum-free conditions

    Microsoft Academic Search

    Weihong Yin; Satish Cheepala; Jennifer N Roberts; Keith Syson-Chan; John DiGiovanni; John L Clifford

    2006-01-01

    BACKGROUND: Squamous cell carcinoma (SCC) of the skin is the most aggressive form of non-melanoma skin cancer (NMSC), and is the single most commonly diagnosed cancer in the U.S., with over one million new cases reported each year. Recent studies have revealed an oncogenic role of activated signal transducer and activator of transcription 3 (Stat3) in many human tumors, especially

  9. Excessive Mechanical Stress Increases HMGB1 Expression in Human Lung Microvascular Endothelial Cells Via STAT3

    PubMed Central

    Garcia, Joe G.N.

    2014-01-01

    Ventilator-induced lung injury (VILI) occurs when the lung parenchyma and vasculature are exposed to repetitive and excessive mechanical stress via mechanical ventilation utilized as supportive care for the adult respiratory distress syndrome (ARDS). VILI induces gene expression and systemic release of inflammatory mediators that contribute to the multi-organ dysfunction and morbidity and mortality of ARDS. HMGB1, an intracellular transcription factor with cytokine properties, is a late mediator in sepsis and ARDS pathobiology, however, the role of HMGB1 in VILI remains poorly described. We now report HMGB1 expression in human lung microvessel endothelial cells (EC) exposed to excessive, equibiaxial mechanical stress, an in vitro correlate of VILI. We determined that high amplitude cyclic stretch (18% CS) increased HMGB1 expression (2-4 fold) via a signaling pathway with critical involvement of the transcription factor, STAT3. Concomitant exposure to 18% CS and oxidative stress (H2O2) augmented HMGB1 expression (~13 fold increase) whereas lipopolysaccharide (LPS) challenge increased HMGB1 expression in static EC, but not in 18% CS-challenged EC. In contrast, physiologic, low amplitude cyclic stretch (5% CS) attenuated both oxidative H2O2- and LPS-induced increases in HMGB1 expression, suggesting that physiologic mechanical stress is protective. These results indicate that HMGB1 gene expression is markedly responsive to VILI-mediated mechanical stress, an effect that is augmented by oxidative stress. We speculate that VILI-induced HMGB1 expression acts locally to increase vascular permeability and alveolar flooding, thereby exacerbating systemic inflammatory responses and increasing the likelihood of multi-organ dysfunction. PMID:24370952

  10. Excessive mechanical stress increases HMGB1 expression in human lung microvascular endothelial cells via STAT3.

    PubMed

    Wolfson, Rachel K; Mapes, Brandon; Garcia, Joe G N

    2014-03-01

    Ventilator-induced lung injury (VILI) occurs when the lung parenchyma and vasculature are exposed to repetitive and excessive mechanical stress via mechanical ventilation utilized as supportive care for the adult respiratory distress syndrome (ARDS). VILI induces gene expression and systemic release of inflammatory mediators that contribute to the multi-organ dysfunction and morbidity and mortality of ARDS. HMGB1, an intracellular transcription factor with cytokine properties, is a late mediator in sepsis and ARDS pathobiology, however, the role of HMGB1 in VILI remains poorly described. We now report HMGB1 expression in human lung microvessel endothelial cells (ECs) exposed to excessive, equibiaxial mechanical stress, an in vitro correlate of VILI. We determined that high amplitude cyclic stretch (18% CS) increased HMGB1 expression (2-4-fold) via a signaling pathway with critical involvement of the transcription factor, STAT3. Concomitant exposure to 18% CS and oxidative stress (H?O?) augmented HMGB1 expression (~13 fold increase) whereas lipopolysaccharide (LPS) challenge increased HMGB1 expression in static EC, but not in 18% CS-challenged EC. In contrast, physiologic, low amplitude cyclic stretch (5% CS) attenuated both oxidative H?O?- and LPS-induced increases in HMGB1 expression, suggesting that physiologic mechanical stress is protective. These results indicate that HMGB1 gene expression is markedly responsive to VILI-mediated mechanical stress, an effect that is augmented by oxidative stress. We speculate that VILI-induced HMGB1 expression acts locally to increase vascular permeability and alveolar flooding, thereby exacerbating systemic inflammatory responses and increasing the likelihood of multi-organ dysfunction. PMID:24370952

  11. Alantolactone Induces Apoptosis in HepG2 Cells through GSH Depletion, Inhibition of STAT3 Activation, and Mitochondrial Dysfunction

    PubMed Central

    Khan, Muhammad; Li, Ting; Ahmad Khan, Muhammad Khalil; Rasul, Azhar; Nawaz, Faisal; Sun, Meiyan; Zheng, Yongchen; Ma, Tonghui

    2013-01-01

    Signal transducer and activator of transcription 3 (STAT3) constitutively expresses in human liver cancer cells and has been implicated in apoptosis resistance and tumorigenesis. Alantolactone, a sesquiterpene lactone, has been shown to possess anticancer activities in various cancer cell lines. In our previous report, we showed that alantolactone induced apoptosis in U87 glioblastoma cells via GSH depletion and ROS generation. However, the molecular mechanism of GSH depletion remained unexplored. The present study was conducted to envisage the molecular mechanism of alantolactone-induced apoptosis in HepG2 cells by focusing on the molecular mechanism of GSH depletion and its effect on STAT3 activation. We found that alantolactone induced apoptosis in HepG2 cells in a dose-dependent manner. This alantolactone-induced apoptosis was found to be associated with GSH depletion, inhibition of STAT3 activation, ROS generation, mitochondrial transmembrane potential dissipation, and increased Bax/Bcl-2 ratio and caspase-3 activation. This alantolactone-induced apoptosis and GSH depletion were effectively inhibited or abrogated by a thiol antioxidant, N-acetyl-L-cysteine (NAC). The data demonstrate clearly that intracellular GSH plays a central role in alantolactone-induced apoptosis in HepG2 cells. Thus, alantolactone may become a lead chemotherapeutic candidate for the treatment of liver cancer. PMID:23533997

  12. Teleost IL-6 promotes antibody production through STAT3 signaling via IL-6R and gp130.

    PubMed

    Kaneda, Mitsuru; Odaka, Tomoyuki; Suetake, Hiroaki; Tahara, Daisuke; Miyadai, Toshiaki

    2012-10-01

    Teleost IL-6 is upregulated after antigen stimulation; therefore, we hypothesized that fish IL-6 contributes to antibody production during immune responses against infections. To verify this hypothesis, we first cloned IL-6R and gp130 in fugu (Takifugu rubripes) in the present study. The membrane and soluble forms of IL-6R were identified by the identification of cDNA clones of IL-6R homologues. Three STAT3-docking sites were found in the intracellular region of fugu gp130. Expression analysis showed that fugu IL-6R and gp130 were expressed in mIgM(+) B cells, suggesting that fugu B cells are stimulated by IL-6. Recombinant fugu IL-6 (rfIL-6) increased the gene expression of secretory antibodies by mIgM(+) B cells in vitro. The rfIL-6 and soluble form of rfIL-6R activated STAT3 phosphorylation in the B cells and a cultured cell line transfected with fugu gp130. These results indicate that fugu IL-6 enhances antibody production in the B-cell lineage via gp130 and STAT3 signaling. PMID:22469658

  13. A STAT3-NFkB/DDIT3/CEBP? axis modulates ALDH1A3 expression in chemoresistant cell subpopulations

    PubMed Central

    Canino, Claudia; Luo, YuYing; Marcato, Paola; Blandino, Giovanni; Pass, Harvey I.; Cioce, Mario

    2015-01-01

    Here we studied the relevance and modulation of aldehyde dehydrogenase (ALDH) expression in malignant pleural mesothelioma (MPM) chemoresistant cell subpopulations (ALDHbright cells), which survive pemetrexed + cisplatin treatment in vitro and in vivo. Expression of the ALDH1A3 isoform was invariably enriched in purified ALDHbright cells from multiple MPM cell lines and accounted for the enzymatic activity of those cells. RNAi mediated downregulation of ALDH1A3 reduced the survival of the ALDHbright cells at steady state and, much more, after pemetrexed + cisplatin treatment. We demonstrated, for the first time, that a pSTAT3(tyr705)-NFkB(p65) complex is required for the repression of DDIT3 mRNA and this ensures high levels of CEBP?-dependent ALDH1A3 promoter activity. Inhibition of STAT3-NFkB activity allowed high levels of DDIT3 expression with increased formation of a DDIT3-CEBP? complex. This reduced the occupancy of the ALDH1A3 promoter by CEBP?, thus largely reducing the ALDH1A3 expression. Consequently, survival of ALDHbright cells in pemetrexed + cisplatin-treated cultures was impaired, following increased apoptosis. We show that such a mechanism is relevant in vivo and underlies the action of butein, a dual STAT3-NFkB inhibitor capable of abating the chemoresistance of mesothelioma cells in vivo. The possible broad translational relevance of the described mechanism is discussed. PMID:25868979

  14. Nuclear translocation of the transcription factor STAT3 in the guinea pig brain during systemic or localized inflammation

    PubMed Central

    Rummel, Christoph; Hübschle, Thomas; Gerstberger, Rüdiger; Roth, Joachim

    2004-01-01

    The purpose of the present study was to investigate a possible lipopolysaccharide (LPS)-induced activation of brain cells that is mediated by the pleiotropic cytokine interleukin-6 (IL-6) and its transcription factor STAT3 during systemic or localized inflammation. In guinea pigs, intra-arterial (i.a., 10 ?g kg?1) or intraperitoneal (i.p., 30 ?g kg?1) injections of bacterial LPS cause a systemic inflammatory response which is accompanied by a robust fever. A febrile response can also be induced by administration of LPS into artificial subcutaneously implanted Teflon chambers (s.c. 100 or 10 ?g kg?1), which reflects an experimental model that mimics local tissue inflammation. Baseline plasma levels of bioactive IL-6 determined 60 min prior to injections of LPS or vehicle amounted to 35–80 international units (i.u.) ml?1. Within 90 min of LPS injection, plasma IL-6 rose about 1000-fold in the groups injected i.a. or i.p., about 50-fold in the group injected s.c. with 100 ?g kg?1 LPS, and only 5-fold in guinea pigs injected with the lower dose of LPS (10 ?g kg?1). At this time point, a distinct nuclear translocation pattern of the transcription factor STAT3 became evident in several brain structures. Amongst those, the sensory circumventricular organs known to lack a tight blood—brain barrier such as the area postrema, the vascular organ of the lamina terminalis and the subfornical organ, as well as the hypothalamic supraoptic nucleus showed intense nuclear STAT3 signals in the i.a. or i.p. injected groups. In contrast a moderate (s.c. group, 100 ?g kg?1), or even no (s.c. group, 10 ?g kg?1), nuclear STAT3 translocation occurred in response to s.c. injections of LPS. These results suggest that STAT3-mediated genomic activation of target gene transcription in brain cells occurred only in those cases in which sufficiently high concentrations of circulating IL-6 were formed during systemic (i.a.. and i.p. groups) or localized (s.c. group, 100 ?g kg?1) inflammation. PMID:14966301

  15. Expression and activation of EGFR and STAT3 during the multistage carcinogenesis of intrahepatic cholangiocarcinoma induced by 3’-methyl-4 dimethylaminoazobenzene in rats

    PubMed Central

    Zhang, Fan; Li, Lianhong; Yang, Xingwu; Wang, Bo; Zhao, Jinyao; Lu, Shilun; Yu, Xiaotang

    2015-01-01

    The purpose of this study was to investigate whether the epidermal growth factor receptor (EGFR) and signal transducer and activator of transcription-3 (STAT3) signal pathway contributes to the carcinogenesis of intrahepatic cholangiocarcinoma (ICC) induced by 3’-methyl-4 dimethylaminoazobenzene (3’Me-DAB) in rats. EGFR, TGF?, STAT3 and p-STAT3 in different stages of carcinogenesis were detected by immunohistochemistry (IHC). In situ hybridization (ISH) was applied to investigate the expression of STAT3 mRNA. Oval cells were verified by the immunohistochemical staining of alpha-fetoprotein (AFP), CD133 and epithelial cell adhesion molecules (EpCAM). Sequential development of necrosis, oval cell proliferation, cholangiofibrosis (CF) and ICC was observed in the liver of rats administered 3’Me-DAB. Oval cells showed positive expression of AFP, CD133 and EpCAM. The expression of EGFR was significantly higher in the ICC than in oval cells, CF or normal bile ducts (p<0.05), but there was no difference in EGFR expression between the other groups. The highest expression of p-STAT3 and TGF? was observed in CF. The expression of these two molecules in the ICC and oval cells was significantly higher than in normal bile ducts (p<0.05). Elevation of STAT3 mRNA was detected during carcinogenesis as shown by ISH, strong intensity was observed in the ICC and moderate intensity was observed in oval cells and CF. These observations suggest that the EGFR and STAT3 signal pathway contributes to the carcinogenesis of ICC. High activity of STAT3 during the carcinogenesis of ICC may be the result of high activity of EGFR triggered by TGF?.

  16. Essential Role of STAT3 in the Control of the Acute-Phase Response as Revealed by Inducible Gene Activation in the Liver

    Microsoft Academic Search

    TONINO ALONZI; DIEGO MARITANO; BARBARA GORGONI; GABRIELLA RIZZUTO; CLAUDE LIBERT; VALERIA POLI

    2001-01-01

    We generated mice carrying a STAT3 allele amenable to Cre-mediated deletion and intercrossed them with Mx-Cre transgenic mice, in which the expression of Cre recombinase can be induced by type I interferon. Interferon-induced deletion of STAT3 occurred very efficiently (more than 90%) in the liver and slightly less efficiently (about 70%) in the bone marrow. Analysis of the induction of

  17. Foxm1 Mediates LIF/Stat3-Dependent Self-Renewal in Mouse Embryonic Stem Cells and Is Essential for the Generation of Induced Pluripotent Stem Cells

    PubMed Central

    Tan, Guixiang; Cheng, Liang; Chen, Tuanhui; Yu, Li; Tan, Yongjun

    2014-01-01

    Activation of signal transducer and activator of transcription 3 (Stat3) by leukemia inhibitory factor (LIF) is required for maintaining self-renewal and pluripotency of mouse embryonic stem cells (mESCs). Here, we have confirmed transcription factor Forkhead Box m1 (Foxm1) as a LIF/Stat3 downstream target that mediates LIF/Stat3-dependent mESC self-renewal. The expression of Foxm1 relies on LIF signaling and is stimulated by Stat3 directly in mESCs. The knockdown of Foxm1 results in the loss of mESC pluripotency in the presence of LIF, and the overexpression of Foxm1 alone maintains mESC pluripotency in the absence of LIF and feeder layers, indicating that Foxm1 is a mediator of LIF/Stat3-dependent maintenance of pluripotency in mESCs. Furthermore, the inhibition of Foxm1 expression prevents the reprogramming of mouse embryonic fibroblasts to induced pluripotent stem cells (iPSCs), suggesting that Foxm1 is essential for the reprogramming of somatic cells into iPSCs. Our results reveal an essential function of Foxm1 in the LIF/Stat3-mediated mESC self-renewal and the generation of iPSCs. PMID:24743237

  18. STAT3 activation by KSHV correlates with IL-10, IL-6 and IL-23 release and an autophagic block in dendritic cells

    PubMed Central

    Santarelli, Roberta; Gonnella, Roberta; Di Giovenale, Giulia; Cuomo, Laura; Capobianchi, Angela; Granato, Marisa; Gentile, Giuseppe; Faggioni, Alberto; Cirone, Mara

    2014-01-01

    Kaposis's sarcoma associated herpesvirus (KSHV) has been reported to infect, among others, monocytes and dendritic cells DCs impairing their function. However, the underlying mechanisms remain not completely elucidated yet. Here we show that DC exposure to active or UV-inactivated KSHV resulted in STAT3 phosphorylation. This effect, partially dependent on KSHV-engagement of DC-SIGN, induced a high release of IL-10, IL-6 and IL-23, cytokines that in turn might maintain STAT3 in a phosphorylated state. STAT3 activation also correlated with a block of autophagy in DCs, as indicated by LC3II reduction and p62 accumulation. The IL-10, IL-6 and IL-23 release and the autophagic block could be overcome by inhibiting STAT3 activation, highlighting the role of STAT3 in mediating such effects. In conclusion, here we show that STAT3 activation can be one of the molecular mechanisms leading to KSHV-mediated DC dysfunction, that might allow viral persistence and the onset of KSHV-associated malignancies. PMID:24577500

  19. IL-22+CD4+ T cells promote colorectal cancer stemness via STAT3 transcription factor activation and induction of the methyltransferase DOT1L

    PubMed Central

    Peng, Dongjun; Zhao, Lili; Zhao, Ende; Vatan, Linda; Szeliga, Wojciech; Dou, Yali; Owens, Scott; Zgodzinski, Witold; Majewski, Marek; Wallner, Grzegorz; Fang, Jingyuan; Huang, Emina; Zou, Weiping

    2014-01-01

    Little is known about how the immune system impacts human colorectal cancer invasiveness and stemness. Here we detected interleukin-22 (IL-22) in patient colorectal cancer tissues that was produced predominantly by CD4+ T cells. In a mouse model, migration of these cells into the colon cancer microenvironment required the chemokine receptor CCR6 and its ligand CCL20. IL-22 acted on cancer cells to promote activation of the transcription factor STAT3 and expression of the histone 3 lysine 79 (H3K79) methytransferase DOT1L. The DOT1L complex induced the core stem cell genes NANOG, SOX2 and Pou5F1, resulting in increased cancer stemness and tumorigenic potential. Furthermore, high DOT1L expression and H3K79me2 in colorectal cancer tissues was a predictor of poor patient survival. Thus, IL-22+ cells promote colon cancer stemness via regulation of stemness genes which negatively affects patient outcome. Efforts to target this network might be a strategy in treating colorectal cancer patients. PMID:24816405

  20. A Novel Strategy for Inducing the Antitumor Effects of Triterpenoid Compounds: Blocking the Protumoral Functions of Tumor-Associated Macrophages via STAT3 Inhibition

    PubMed Central

    Komohara, Yoshihiro

    2014-01-01

    There are many types of nontumor cells, including leukocytes, fibroblasts, and endothelial cells, in the tumor microenvironment. Among these cells, infiltrating macrophages have recently received attention as novel target cells due to their protumoral functions. Infiltrating macrophages are called tumor-associated macrophages (TAMs). TAMs polarized to the M2 phenotype are involved in tumor development and are associated with a poor clinical prognosis. Therefore, the regulation of TAM activation or M2 polarization is a new strategy for antitumor therapy. We screened natural compounds possessing an inhibitory effect on the M2 polarization of human macrophages. Among 200 purified natural compounds examined, corosolic acid (CA) and oleanolic acid (OA), both are categorized in triterpenoid compounds, inhibited macrophage polarization to M2 phenotype by suppressing STAT3 activation. CA and OA also directly inhibited tumor cell proliferation and sensitized tumor cells to anticancer drugs, such as adriamycin and cisplatin. The in vivo experiments showed that CA significantly suppressed subcutaneous tumor development and lung metastasis in a murine sarcoma model. The application of triterpenoid compounds, such as CA and OA, is a potential new anticancer therapy targeting macrophage activation, with synergistic effects with anticancer agents. PMID:24738052

  1. Proline protects liver from D-galactosamine hepatitis by activating the IL-6/STAT3 survival signaling pathway.

    PubMed

    Obayashi, Yoko; Arisaka, Harumi; Yoshida, Shintaro; Mori, Masato; Takahashi, Michio

    2012-12-01

    The oral administration of proline, one of the non-essential amino acids, has been shown to effectively protect the liver from D-galactosamine (GalN)-induced liver injury and to improve the survival rate. The aim of this study was to investigate the mechanism of this protective action of proline. We paid particular attention to the effect of proline on inflammatory activation, regenerative response, and the associated signal transduction in the liver. Male Fischer rats received intraperitoneal injections of GalN (1.4 g/kg) with or without the oral administration of proline (2 g/kg) 1 h before GalN treatment. Liver pathology, plasma indices of inflammation, and the level of proliferative marker in the liver were monitored. The hepatic activation of interleukin-6 (IL-6)/signal transducer and activator of transcription (STAT)-3 pathway, which is downstream of tumor necrosis factor (TNF)-?/nuclear factor-?B, was also studied. GalN induced massive inflammatory expansion in the liver, leading to a high death rate (60 %) more than 72 h after the treatment. Proline administration significantly suppressed inflammatory infiltration in the live after 48 h, which was accompanied by depletion of plasma TNF-?, glutamic oxaloacetic transaminase, and glutamic pyruvic transaminase. The mRNA expression of histone H3, a marker of proliferation, was significantly upregulated in the liver of proline-treated animals. Furthermore, IL-6/STAT-3 pathway, an anti-inflammatory and regenerative signaling pathway, was strongly activated prior to these observations, with the upregulated expression of downstream genes. These results suggest that the tissue-protective mechanism of proline involves the early activation of IL-6/STAT-3 pathway in the liver, with subsequent activation of the regenerative response and suppression of massive inflammatory activation. PMID:22585093

  2. The role of the JAK2-STAT3 pathway in pro-inflammatory responses of EMF-stimulated N9 microglial cells

    PubMed Central

    2010-01-01

    Background In several neuropathological conditions, microglia can become overactivated and cause neurotoxicity by initiating neuronal damage in response to pro-inflammatory stimuli. Our previous studies have shown that exposure to electromagnetic fields (EMF) activates cultured microglia to produce tumor necrosis factor (TNF)-? and nitric oxide (NO) through signal transduction involving the activator of transcription STAT3. Here, we investigated the role of STAT3 signaling in EMF-induced microglial activation and pro-in?ammatory responses in more detail than the previous study. Methods N9 microglial cells were treated with EMF exposure or a sham treatment, with or without pretreatment with an inhibitor (Pyridone 6, P6) of the Janus family of tyrosine kinases (JAK). The activation state of microglia was assessed via immunoreaction using the microglial marker CD11b. Levels of inducible nitric oxide synthase (iNOS), TNF-? and NO were measured using real-time reverse transcription-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA) and the nitrate reductase method. Activation of JAKs and STAT3 proteins was evaluated by western blotting for specific tyrosine phosphorylation. The ability of STAT3 to bind to DNA was detected with an electrophoresis mobility shift assay (EMSA). Results EMF was found to significantly induce phosphorylation of JAK2 and STAT3, and DNA-binding ability of STAT3 in N9 microglia. In addition, EMF dramatically increased the expression of CD11b, TNF-? and iNOS, and the production of NO. P6 strongly suppressed the phosphorylation of JAK2 and STAT3 and diminished STAT3 activity in EMF-stimulated microglia. Interestingly, expression of CD11b as well as gene expression and production of TNF-? and iNOS were suppressed by P6 at 12 h, but not at 3 h, after EMF exposure. Conclusions EMF exposure directly triggers initial activation of microglia and produces a significant pro-inflammatory response. Our findings confirm that the JAK2-STAT3 pathway may not mediate this initial microglial activation but does promote pro-inflammatory responses in EMF-stimulated microglial cells. Thus, the JAK2-STAT3 pathway might be a therapeutic target for reducing pro-inflammatory responses in EMF-activated microglia. PMID:20828402

  3. MicroRNA-10a silencing reverses cisplatin resistance in the A549/cisplatin human lung cancer cell line via the transforming growth factor-?/Smad2/STAT3/STAT5 pathway.

    PubMed

    Sun, Wei; Ma, Yiping; Chen, Peng; Wang, Dong

    2015-05-01

    Lung cancer is one of the primary causes of mortality worldwide and drug resistance is the key contributing factor which results in the failure of lung cancer chemotherapy. Previous studies have shown that microRNA (miR)?10a was involved in the reversal of cisplatin (DDP) resistance in numerous types of tumors; however, the underlying mechanism of action of this remains to be fully elucidated. In the present study, miR?10a silencing in human DDP?resistant lung cancer A549/DDP cells was demonstrated to improve DDP sensitivity, apoptosis, intracellular rhodamine?123 content as well as the expression and activity of caspase?3/8. In addition, miR?10a suppressed the cellular expression of P?glycoprotein, multi?drug resistance protein (MDR) 1, MDR?associated protein 1, RhoE, B cell lymphoma?2 and survivin in A549/DDP cells. Furthermore, miR?10a silencing inhibited the secretion of transforming growth factor (TGF)??, phosphorylation of Sma? and Mad?related protein (Smad)2, signal transducer and activator of transcription (STAT)3 and STAT5, the transcriptional activity of hypoxia?inducible factor and eukaryotic translation initiation factor 4E in human lung cancer A549/DDP cell line. These results therefore indicated that miR?10a may be a potential target for improving the effectiveness of lung cancer chemotherapy via regulation of the TGF??/Smad2/STAT3/STAT5 pathway. PMID:25586740

  4. Intranuclear Crosstalk between Extracellular Regulated Kinase1/2 and Signal Transducer and Activator of Transcription 3 Regulates JEG-3 Choriocarcinoma Cell Invasion and Proliferation

    PubMed Central

    Morales-Prieto, Diana M.; Ospina-Prieto, Stephanie; Weber, Maja; Schleussner, Ekkehard; Fitzgerald, Justine S.; Markert, Udo R.

    2013-01-01

    Invasiveness of trophoblast and choriocarcinoma cells is in part mediated via leukemia inhibitory factor- (LIF-) induced activation of signal transducer and activator of transcription 3 (STAT3). The regulation of STAT3 phosphorylation at its ser727 binding site, possible crosstalk with intracellular MAPK signaling, and their functional implications are the object of the present investigation. JEG-3 choriocarcinoma cells were cultured in presence/absence of LIF and the specific ERK1/2 inhibitor (U0126). Phosphorylation of signaling molecules (p-STAT3 (ser727 and tyr705) and p-ERK1/2 (thr 202/tyr 204)) was assessed per Western blot. Immunocytochemistry confirmed results, but also pinpointed the location of phosphorylated signaling molecules. STAT3 DNA-binding capacity was studied with a colorimetric ELISA-based assay. Cell viability and invasion capability were assessed by MTS and Matrigel assays. Our results demonstrate that LIF-induced phosphorylation of STAT3 (tyr705 and ser727) is significantly increased after blocking ERK1/2. STAT3 DNA-binding capacity and cell invasiveness are enhanced after LIF stimulation and ERK1/2 blockage. In contrast, proliferation is enhanced by LIF but reduced after ERK1/2 inhibition. The findings herein show that blocking ERK1/2 increases LIF-induced STAT3 phosphorylation and STAT3 DNA-binding capacity by an intranuclear crosstalk, which leads to enhanced invasiveness and reduced proliferation. PMID:24288470

  5. Activation of Nicotinic Receptors Inhibits TNF-?-Induced Production of Pro-inflammatory Mediators Through the JAK2/STAT3 Signaling Pathway in Fibroblast-Like Synoviocytes.

    PubMed

    Li, Tong; Wu, Shiyao; Zhang, Huali; Wang, Yanping; Luo, Hui; Zuo, Xiaoxia; Xiao, Xianzhong

    2015-08-01

    It was recently demonstrated that stimulation of the nicotine receptor attenuates collagen-induced arthritis and inhibits cytokine release in mice. We elucidated the possible intracellular signaling mechanism of the cholinergic anti-inflammatory pathway in fibroblast-like synoviocytes (FLSs). Levels of interleukin (IL)-6, IL-10, and monocyte chemoattractant protein (MCP)-1 in culture supernatants of tumor necrosis factor (TNF)-?-stimulated FLSs were measured using an enzyme-linked immunosorbent assay (ELISA). FLSs were transfected with a small interfering RNA oligonucleotide (STAT3 siRNA or control siRNA). AG490, a specific inhibitor of JAK2, was added 16 h before nicotine, and blocker of nAChR was added 30 min before nicotine. Activation of signal transducers and activators of transcription (STAT) such as STAT1 and STAT3 were detected using Western blotting. Nicotine downregulated production of IL-6 and MCP-1 in RA-FLSs induced by TNF? in a concentration-dependent manner, and IL-10 levels were not significantly different after nicotine pretreatment. Nicotine-induced activation of STAT3 (but not STAT1) and deactivation of STAT3 decreased the anti-inflammatory effect of nicotine. AG490 inhibited the phosphorylation of STAT1 and STAT3 and decreased the TNF-?-induced production of pro-inflammatory mediators in RA-FLSs. A ?7nAChR antagonist abrogated the anti-inflammatory effects of nicotine and suppressed STAT3 activity. In conclusion, nicotine has an anti-inflammatory effect on RA by downregulating production of IL-6 and MCP-1 in FLSs, and this is mediated through activation of the JAK2-STAT3 signal pathway. PMID:25616906

  6. In vivo and in vitro evidence that chronic activation of the hexosamine biosynthetic pathway interferes with leptin-dependent STAT3 phosphorylation.

    PubMed

    Zimmerman, Arthur D; Harris, Ruth B S

    2015-03-15

    We previously reported that a 2-day peripheral infusion of glucosamine caused leptin resistance in rats, suggesting a role for the hexosamine biosynthetic pathway (HBP) in the development of leptin resistance. Here we tested leptin responsiveness in mice in which HBP activity was stimulated by offering 30% sucrose solution in addition to chow and water or by infusing glucosamine. Mice were leptin resistant after 33 days of access to sucrose. Resistance was associated with increased activity of the HBP and with phosphorylation of transcription factor signal transducer and activator of transcription-3 Tyr705 [pSTAT3(Y705)] but inhibition of suppressor of cytokine signaling 3 in the liver and hypothalamus. Intravenous infusion of glucosamine for 3 h stimulated pSTAT3(Y705) but prevented leptin-induced phosphorylation of STAT3(S727). In an in vitro system, glucose, glucosamine, and leptin each dose dependently increased O-linked ?-N-acetylglucosamine (O-GlcNAc) protein and pSTAT3(Y705) in HepG2 cells. To test the effect of glucose on leptin responsiveness cells were incubated in 5.5 mM (LG) or 20 mM (HG) glucose for 18 h and were treated with 0 or 50 ng/ml leptin for 15 min. HG alone and LG + leptin produced similar increases in O-GlcNAc protein, glutamine fructose-6-phosphate amidotransferase (GFAT), and pSTAT3(Y705) compared with LG media. Leptin did not stimulate these proteins in HG cells, suggesting leptin resistance. Leptin-induced pSTAT3(S727) was prevented by HG media. Inhibition of GFAT with azaserine prevented LG + leptin and HG stimulation of pSTAT3. These data demonstrate development of leptin resistance in sucrose-drinking mice and provide new evidence of leptin-induced stimulation of the HBP. PMID:25568075

  7. Selected contribution: role of IL-6 in LPS-induced nuclear STAT3 translocation in sensory circumventricular organs during fever in rats.

    PubMed

    Harré, Eva-Maria; Roth, Joachim; Pehl, Ulrich; Kueth, Matthias; Gerstberger, Rüdiger; Hübschle, Thomas

    2002-06-01

    Interleukin-6 (IL-6) is regarded as an endogenous mediator of lipopolysaccharide (LPS)-induced fever. IL-6 is thought to act on the brain at sites that lack a blood-brain barrier, the circumventricular organs (CVOs). Cells that are activated by IL-6 respond with nuclear translocation of the signal transducer and activator of transcription 3 molecule (STAT3) and can be detected by immunohistochemistry. We investigated whether the LPS-induced release of IL-6 into the systemic circulation was accompanied by a nuclear STAT3 translocation within the sensory CVOs. Treatment with LPS (100 microg/kg) led to a slight (1 h) and then a strong increase (2-8 h) in plasma IL-6 levels, which started to decline at the end of the febrile response. Administration of both pyrogens LPS and IL-6 (45 microg/kg) induced a febrile response with IL-6, causing a rather moderate fever compared with the LPS-induced fever. Nuclear STAT3 translocation in response to LPS was observed within the vascular organ of the lamina terminalis (OVLT) and the subfornical organ (SFO) 2 h after LPS treatment. To investigate whether this effect was mediated by IL-6, the cytokine itself was systemically applied and indeed an identical pattern of nuclear STAT3 translocation was observed. However, nuclear STAT3 translocation already occurred 1 h after IL-6 application and proved to be less effective compared with LPS treatment when analyzing OVLT and SFO cell numbers that showed nuclear STAT3 immunoreactivity after the respective pyrogen treatment. Our observations represent the first molecular evidence for an IL-6-induced STAT3-mediated genomic activation of OVLT and SFO cells and support the proposed role of these brain areas as sensory structures for humoral signals created by the activated immune system and resulting in the generation of fever. PMID:12015387

  8. ?9-Tetrahydrocannabinol-mediated epigenetic modifications elicit myeloid-derived suppressor cell activation via STAT3/S100A8.

    PubMed

    Sido, Jessica Margaret; Yang, Xiaoming; Nagarkatti, Prakash S; Nagarkatti, Mitzi

    2015-04-01

    MDSCs are potent immunosuppressive cells that are induced during inflammatory responses, as well as by cancers, to evade the anti-tumor immunity. We recently demonstrated that marijuana cannabinoids are potent inducers of MDSCs. In the current study, we investigated the epigenetic mechanisms through which THC, an exogenous cannabinoid, induces MDSCs and compared such MDSCs with the naïve MDSCs found in BM of BL6 (WT) mice. Administration of THC into WT mice caused increased methylation at the promoter region of DNMT3a and DNMT3b in THC-induced MDSCs, which correlated with reduced expression of DNMT3a and DNMT3b. Furthermore, promoter region methylation was decreased at Arg1 and STAT3 in THC-induced MDSCs, and consequently, such MDSCs expressed higher levels of Arg1 and STAT3. In addition, THC-induced MDSCs secreted elevated levels of S100A8, a calcium-binding protein associated with accumulation of MDSCs in cancer models. Neutralization of S100A8 by use of anti-S100A8 (8H150) in vivo reduced the ability of THC to trigger MDSCs. Interestingly, the elevated S100A8 expression also promoted the suppressive function of MDSCs. Together, the current study demonstrates that THC mediates epigenetic changes to promote MDSC differentiation and function and that S100A8 plays a critical role in this process. PMID:25713087

  9. Modulation of dendritic cell differentiation by HLA-G and ILT4 requires the IL-6—STAT3 signaling pathway

    PubMed Central

    Liang, Siyuan; Ristich, Vladimir; Arase, Hisashi; Dausset, Jean; Carosella, Edgardo D.; Horuzsko, Anatolij

    2008-01-01

    The expression of Ig-like transcript (ILT) inhibitory receptors is a characteristic of tolerogenic dendritic cells (DCs). However, the mechanisms of modulation of DCs via ILT receptors remain poorly defined. HLA-G is a preferential ligand for several ILTs. Recently, we demonstrated that triggering of ILT4 by HLA-G1 inhibits maturation of human monocyte-derived conventional DCs and murine DCs from ILT4 transgenic mice, resulting in diminished expression of MHC class II molecules, CD80 and CD86 costimulatory molecules, and prolongation of skin allograft survival. Different isoforms of HLA-G have diverse effects on the efficiency to induce ILT-mediated signaling. In this work, we show that HLA-G1 tetrameric complex and HLA-G5 dimer, but not HLA-G5 monomer, induce strong ILT-mediated signaling. We determined that the arrest of maturation of ILT4-positive DCs by HLA-G ligands involves the IL-6 signaling pathway and STAT3 activation. Ligation of ILT4 with HLA-G on DCs results in recruitment of SHP-1 and SHP-2 protein tyrosine phosphatases. We propose a model where SHP-2 and the IL-6–STAT3 signaling pathway play critical roles in the modulation of DC differentiation by ILT4 and HLA-G. PMID:18550825

  10. ?-Tocotrienol Induces Human Bladder Cancer Cell Growth Arrest, Apoptosis and Chemosensitization through Inhibition of STAT3 Pathway

    PubMed Central

    Yan, Xiang; Lu, Qun; Chang, Cunjie; Huang, Xiaojing; Zhou, Ji; Xie, Bingxian; Zhang, Zhen; Yao, Xin; Yan, Jun; Guo, Hongqian

    2015-01-01

    Vitamin E intake has been implicated in reduction of bladder cancer risk. However, the mechanisms remain elusive. Here we reported that ?-tocotrienol (?-T3), one of vitamin E isomers, possessed the most potent cytotoxic capacity against human bladder cancer cells, compared with other Vitamin E isomers. ?-T3 inhibited cancer cell proliferation and colonogenicity through induction of G1 phase arrest and apoptosis. Western blotting assay revealed that ?-T3 increased the expression levels of cell cycle inhibitors (p21, p27), pro-apoptotic protein (Bax) and suppressed expression levels of cell cycle protein (Cyclin D1), anti-apoptotic proteins (Bcl-2, Bcl-xL and Mcl-1), resulting in the Caspase-3 activation and cleavage of PARP. Moreover, the ?-T3 treatment inhibited ETK phosphorylation level and induced SHP-1 expression, which was correlated with downregulation of STAT3 activation. In line with this, ?-T3 reduced the STAT3 protein level in nuclear fraction, as well as its transcription activity. Knockdown of SHP-1 partially reversed ?-T3-induced cell growth arrest. Importantly, low dose of ?-T3 sensitized Gemcitabine-induced cytotoxic effects on human bladder cancer cells. Overall, our findings demonstrated, for the first time, the cytotoxic effects of ?-T3 on bladder cancer cells and suggest that ?-T3 might be a promising chemosensitization reagent for Gemcitabine in bladder cancer treatment. PMID:25849286

  11. Nucleophosmin/anaplastic lymphoma kinase (NPM/ALK) oncoprotein induces the T regulatory cell phenotype by activating STAT3

    PubMed Central

    Kasprzycka, Monika; Marzec, Michal; Liu, Xiaobin; Zhang, Qian; Wasik, Mariusz A.

    2006-01-01

    The mechanisms of malignant cell transformation mediated by the oncogenic, chimeric nucleophosmin/anaplastic lymphoma kinase (NPM/ALK) tyrosine kinase remain only partially understood. Here we report that the NPM/ALK-carrying T cell lymphoma (ALK+TCL) cells secrete IL-10 and TGF-? and express FoxP3, indicating their T regulatory (Treg) cell phenotype. The secreted IL-10 suppresses proliferation of normal immune, CD3/CD28-stimulated peripheral blood mononuclear cells and enhances viability of the ALK+TCL cells. The Treg phenotype of the affected cells is strictly dependent on NPM/ALK expression and function as demonstrated by transfection of the kinase into BaF3 cells and inhibition of its enzymatic activity and expression in ALK+TCL cells. NPM/ALK, in turn, induces the phenotype through activation of its key signal transmitter, signal transducer and activator of transcription 3 (STAT3). These findings identify a mechanism of NPM/ALK-mediated oncogenesis based on induction of the Treg phenotype of the transformed CD4+ T cells. These results also provide an additional rationale to therapeutically target the chimeric kinase and/or STAT3 in ALK+TCL. PMID:16766651

  12. Qishenyiqi Protects Ligation-Induced Left Ventricular Remodeling by Attenuating Inflammation and Fibrosis via STAT3 and NF-?B Signaling Pathway

    PubMed Central

    Shi, Tianjiao; Wu, Yan; Han, Jing; Chai, Xingyun; Wang, Wei

    2014-01-01

    Aim Qi-shen-yi-qi (QSYQ), a formula used for the routine treatment of heart failure (HF) in China, has been demonstrated to improve cardiac function through down-regulating the activation of the Renin-Angiotensin-Aldosterone System (RAAS). However, the mechanisms governing its therapeutic effects are largely unknown. The present study aims to demonstrate that QSYQ treatment can prevent left ventricular remodeling in heart failure by attenuating oxidative stress and inhabiting inflammation. Methods Sprague-Dawley (SD) rats were randomly divided into 6 groups: sham group, model group (LAD coronary artery ligation), QSYQ group with high dosage, middle dosage and low dosage (LAD ligation and treated with QSYQ), and captopril group (LAD ligation and treated with captopril as the positive drug). Indicators of fibrosis (Masson, MMPs, and collagens) and inflammation factors were detected 28 days after surgery. Results Results of hemodynamic alterations (dp/dt value) in the model group as well as other ventricular remodeling (VR) markers, such as MMP-2, MMP-9, collagen I and III elevated compared with sham group. VR was accompanied by activation of RAAS (angiotensin II and NADPHoxidase). Levels of pro-inflammatory cytokines (TNF-?, IL-6) in myocardial tissue were also up-regulated. Treatment of QSYQ improved cardiac remodeling through counter-acting the aforementioned events. The improvement of QSYQ was accompanied with a restoration of angiotensin II-NADPHoxidase-ROS-MMPs pathways. In addition, “therapeutic” QSYQ administration can reduce both TNF-?-NF-B and IL-6-STAT3 pathways, respectively, which further proves the beneficial effects of QSYQ. Conclusions Our study demonstrated that QSYQ protected LAD ligation-induced left VR via attenuating AngII -NADPH oxidase pathway and inhabiting inflammation. These findings provide evidence as to the cardiac protective efficacy of QSYQ to HF and explain the beneficial effects of QSYQ in the clinical application for HF. PMID:25122164

  13. Anti-arthritis effects of (E)-2,4-bis(p-hydroxyphenyl)- 2-butenal are mediated by inhibition of the STAT3 pathway

    PubMed Central

    Ban, Jung Ok; Kim, Dae Hwan; Lee, Hee Pom; Hwang, Chul Ju; Shim, Jung-Hyun; Kim, Dae Joong; Kim, Tae Myoung; Jeong, Heon-Sang; Nah, Seong Su; Chen, Hanyong; Dong, Zigang; Ham, Young Wan; Kim, Youngsoo; Han, Sang-Bae; Hong, Jin Tae

    2014-01-01

    Background and Purpose Products of Maillard reactions between aminoacids and reducing sugars are known to have anti-inflammatory properties. Here we have assessed the anti-arthritis effects of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal and its possible mechanisms of action. Experimental Approach We used cultures of LPS-activated macrophages (RAW264.7 cells) and human synoviocytes from patients with rheumatoid arthritis for in vitro assays and the collagen-induced arthritis model in mice. NO generation, iNOS and COX2 expression, and NF-?B/IKK and STAT3 activities were measured in vitro and in joint tissues of arthritic mice, along with clinical scores and histopathological assessments. Binding of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal to STAT3 was evaluated by a pull-down assay and its binding site was predicted using molecular docking studies with Autodock VINA. Key Results (E)-2,4-bis(p-hydroxyphenyl)-2-butenal (2.5–10 ?g·mL?1) inhibited LPS-inducedNO generation, iNOS and COX2 expression, and NF-?B/IKK and STAT3 activities in macrophage and human synoviocytes. This compound also suppressedcollagen-induced arthritic responses in mice by inhibiting expression of iNOS and COX2, and NF-?B/IKK and STAT3 activities; it also reduced bone destruction and fibrosis in joint tissues. A pull-down assay showed that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal interfered with binding of ATP to STAT3. Docking studies suggested that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal bound to the DNA-binding interface of STAT3 possibly inhibiting ATP binding to STAT3 in an allosteric manner. Conclusions and Implications (E)-2,4-bis(p-hydroxyphenyl)-2-butenal exerted anti-inflammatory and anti-arthritic effects through inhibition of the NF-?B/STAT3 pathway by direct binding to STAT3. This compound could be a useful agent for the treatment of arthritic disease. PMID:24520814

  14. Over-expression of CKS1B activates both MEK/ERK and JAK/STAT3 signaling pathways and promotes myeloma cell drug-resistance

    PubMed Central

    Zangari, Maurizio; Xu, Hongwei; Cao, Thai M.; Xu, Chunjiao; Wu, Yong; Xiao, Fang; Liu, Yinghong; Yang, Ye; Salama, Mohamed; Li, Guiyuan; Tricot, Guido; Zhan, Fenghuang

    2010-01-01

    Here we demonstrate the crucial role of CKS1B in multiple myeloma (MM) progression and define CKS1B-mediated SKP2/p27Kip1-independent down-stream signaling pathways. Forced-expression of CKS1B in MM cells increased cell multidrug-resistance. CKS1B activates STAT3 and MEK/ERK pathways. In contrast, SKP2 knockdown or p27Kip1 over-expression resulted in activation of the STAT3 and MEK/ERK pathways. Further investigations showed that BCL2 is a downstream target of MEK/ERK signaling. Stimulation of STAT3 and MEK/ERK signaling pathways partially abrogated CKS1B knockdown induced MM cell death and growth inhibition. Targeting STAT3 and MEK/ ERK signaling pathways by specific inhibitors induced significant MM cell death and growth inhibition in CKS1B-overexpressing MM cells and their combinations resulted in synergy. Thus, our findings provide a rationale for targeting STAT3 and MEK/ERK/ BCL2 signaling in aggressive CKS1B-overexpressing MM. PMID:20930946

  15. Over-expression of CKS1B activates both MEK/ERK and JAK/STAT3 signaling pathways and promotes myeloma cell drug-resistance.

    PubMed

    Shi, Lei; Wang, Siqing; Zangari, Maurizio; Xu, Hongwei; Cao, Thai M; Xu, Chunjiao; Wu, Yong; Xiao, Fang; Liu, Yinghong; Yang, Ye; Salama, Mohamed; Li, Guiyuan; Tricot, Guido; Zhan, Fenghuang

    2010-05-01

    Here we demonstrate the crucial role of CKS1B in multiple myeloma (MM) progression and define CKS1B-mediated SKP2/p27(Kip1)-independent down-stream signaling pathways. Forced-expression of CKS1B in MM cells increased cell multidrug-resistance. CKS1B activates STAT3 and MEK/ERK pathways. In contrast, SKP2 knockdown or p27(Kip1) over-expression resulted in activation of the STAT3 and MEK/ERK pathways. Further investigations showed that BCL2 is a downstream target of MEK/ERK signaling. Stimulation of STAT3 and MEK/ERK signaling pathways partially abrogated CKS1B knockdown induced MM cell death and growth inhibition. Targeting STAT3 and MEK/ERK signaling pathways by specific inhibitors induced significant MM cell death and growth inhibition in CKS1B-overexpressing MM cells and their combinations resulted in synergy. Thus, our findings provide a rationale for targeting STAT3 and MEK/ERK/BCL2 signaling in aggressive CKS1B-overexpressing MM. PMID:20930946

  16. Constitutive activation of STAT3 and STAT5 is present in the majority of nasopharyngeal carcinoma and correlates with better prognosis.

    PubMed

    Hsiao, J-R; Jin, Y-T; Tsai, S-T; Shiau, A-L; Wu, C-L; Su, W-C

    2003-07-21

    Constitutively activated signal transducers and activators of transcription (STAT) factors, in particular STAT1, STAT3 and STAT5, have been demonstrated in a variety of human tumours and cancer cell lines. However, data on the expression of these STATs in nasopharyngeal carcinoma (NPC) are limited. In this study, the expression patterns of STAT1, STAT3 and STAT5 were immunohistochemically examined on the archival specimens from 61 patients with NPC. Staining results of each STATs were then correlated with the clinical parameters and prognosis of these patients. The results showed that constitutive activation of STAT3 and STAT5 was detected in the majority, 70.5 and 62.3%, respectively, of the 61 tumour specimens. Furthermore, coexpression of activated STAT3 and STAT5 was found in 54.1% of the specimens. In contrast, constitutive activated STAT1 could only be detected in 8 (13.1%) cases. Surprisingly, following radiotherapy, patients with constitutive STAT5 activation, or activation of both STAT3 and STAT5, had better disease-free survival and overall survival than those without activated STAT5. To our knowledge, this is the first report providing the overall expression patterns and prognostic significance of specific STATs in NPC. PMID:12865928

  17. Inhibition of STAT3, FAK and Src mediated signaling reduces cancer stem cell load, tumorigenic potential and metastasis in breast cancer

    PubMed Central

    Thakur, Ravi; Trivedi, Rachana; Rastogi, Namrata; Singh, Manisha; Mishra, Durga Prasad

    2015-01-01

    Cancer stem cells (CSCs) are responsible for aggressive tumor growth, metastasis and therapy resistance. In this study, we evaluated the effects of Shikonin (Shk) on breast cancer and found its anti-CSC potential. Shk treatment decreased the expression of various epithelial to mesenchymal transition (EMT) and CSC associated markers. Kinase profiling array and western blot analysis indicated that Shk inhibits STAT3, FAK and Src activation. Inhibition of these signaling proteins using standard inhibitors revealed that STAT3 inhibition affected CSCs properties more significantly than FAK or Src inhibition. We observed a significant decrease in cell migration upon FAK and Src inhibition and decrease in invasion upon inhibition of STAT3, FAK and Src. Combined inhibition of STAT3 with Src or FAK reduced the mammosphere formation, migration and invasion more significantly than the individual inhibitions. These observations indicated that the anti-breast cancer properties of Shk are due to its potential to inhibit multiple signaling proteins. Shk also reduced the activation and expression of STAT3, FAK and Src in vivo and reduced tumorigenicity, growth and metastasis of 4T1 cells. Collectively, this study underscores the translational relevance of using a single inhibitor (Shk) for compromising multiple tumor-associated signaling pathways to check cancer metastasis and stem cell load. PMID:25973915

  18. Signal transducer and activator of transcription 3 (Stat3C) promotes myeloid-derived suppressor cell expansion and immune suppression during lung tumorigenesis.

    PubMed

    Wu, Lingyan; Du, Hong; Li, Yuan; Qu, Peng; Yan, Cong

    2011-10-01

    Signal transducer and activator of transcription 3 (Stat3) is a potent transcription factor with diverse biological functions. Overexpression of constitutively active form Stat3C in lung alveolar type II (AT II) epithelial cells in CCSP-rtTA/(tetO)(7)-CMV-Stat3C bitransgenic mice induces chronic inflammation and lung bronchioalveolar adenocarcinoma. In the present study, the population of CD11b(+)Gr-1(+) myeloid-derived suppressor cells (MDSCs) was significantly increased in lung and blood of doxycycline-treated bitransgenic mice, but CD4(+) and CD8(+) T cells were decreased. In bronchioalveolar lavage fluid and plasma of doxycycline-treated bitransgenic mice, concentrations of MDSC-stimulating cytokines IL-1?, IL-6, IL-10, IL-13, INF-?, TNF-?, and GM-CSF were significantly increased, which stimulated alveolar monocytes/macrophages to CD11b(+)Gr-1(+) cell conversion in vitro. Phosphorylation of proto-oncogenic intracellular signaling molecules Stat3, Erk1/2, and P38 was significantly increased in CD11b(+)Gr-1(+) cells from lung and blood of doxycycline-treated bitransgenic mice. CD11b(+)Gr-1(+) cells from lung of doxycycline-treated bitransgenic mice strongly inhibited proliferation and function of wild-type CD4(+) T cells in vitro. These findings support the concept that persistent activation of Stat3 induces inflammation during lung cancer by promoting MDSC-mediated immune suppression. PMID:21864492

  19. Acquisition of resistance to trastuzumab in gastric cancer cells is associated with activation of IL-6/STAT3/Jagged-1/Notch positive feedback loop

    PubMed Central

    Liu, Dan; Sun, Limin; Chen, Hongyu; Deng, Que; Liu, Yanjun; Yu, Ming; Ma, Yuanfang; Guo, Ning; Shi, Ming

    2015-01-01

    In the present study, we demonstrate that prolonged treatment by trastuzumab induced resistance of NCI-N87 gastric cancer cells to trastuzumab. The resistant cells possessed typical characteristics of epithelial to mesenchymal transition (EMT)/cancer stem cells and acquired more invasive and metastatic potentials both in vitro and in vivo. Long term treatment with trastuzumab dramatically inhibited the phosphorylation of Akt, but triggered the activation of STAT3. The level of IL-6 was remarkably increased, implicating that the release of IL-6 that drives the STAT3 activation initiates the survival signaling transition. Furthermore, the Notch activities were significantly enhanced in the resistant cells, companied by upregulation of the Notch ligand Jagged-1 and the Notch responsive genes Hey1 and Hey2. Inhibiting the endogenous Notch pathway reduced the IL-6 expression and restored the sensitivities of the resistant cells to trastuzumab. Blocking of the STAT3 signaling abrogated IL-6-induced Jagged-1 expression, effectively inhibited the growth of the trastuzumab resistant cells, and enhanced the anti-tumor activities of trastuzumab in the resistant cells. These findings implicate that the IL-6/STAT3/Jagged-1/Notch axis may be a useful target and that combination of the Notch or STAT3 inhibitors with trastuzumab may prevent or delay clinical resistance and improve the efficacy of trastuzumab in gastric cancer. PMID:25669984

  20. Inhibition of STAT3 signaling and induction of SHP1 mediate antiangiogenic and antitumor activities of ergosterol peroxide in U266 multiple myeloma cells

    PubMed Central

    2012-01-01

    Background Ergosterol peroxide (EP) derived from edible mushroom has been shown to exert anti-tumor activity in several cancer cells. In the present study, anti-angiogenic activity of EP was investigated with the underlying molecular mechanisms in human multiple myeloma U266 cells. Results Despite weak cytotoxicity against U266 cells, EP suppressed phosphorylation, DNA binding activity and nuclear translocalization of signal transducer and activator of transcription 3 (STAT3) in U266 cells at nontoxic concentrations. Also, EP inhibited phosphorylation of the upstream kinases Janus kinase 2 (JAK2) and Src in a time-dependent manner. Furthermore, EP increased the expression of protein tyrosine phosphatase SHP-1 at protein and mRNA levels, and conversely silencing of the SHP-1 gene clearly blocked EP-mediated STAT3 inactivation. In addition, EP significantly decreased vascular endothelial growth factor (VEGF), one of STAT3 target genes at cellular and protein levels as well as disrupted in vitro tube formation assay. Moreover, EP significantly suppressed the growth of U266 cells inoculated in female BALB/c athymic nude mice and immunohistochemistry revealed that EP effectively reduced the expression of STAT3 and CD34 in tumor sections compared to untreated control. Conclusion These findings suggest that EP can exert antitumor activity in multiple myeloma U266 cells partly with antiangiogenic activity targeting JAK2/STAT3 signaling pathway as a potent cancer preventive agent for treatment of multiple myeloma cells. PMID:22260501

  1. Herbal Extract SH003 Suppresses Tumor Growth and Metastasis of MDA-MB-231 Breast Cancer Cells by Inhibiting STAT3-IL-6 Signaling

    PubMed Central

    Woo, Sang-Mi; Park, Sunju; Shin, Yong Cheol; Ko, Seong-Gyu

    2014-01-01

    Cancer inflammation promotes cancer progression, resulting in a high risk of cancer. Here, we demonstrate that our new herbal extract, SH003, suppresses both tumor growth and metastasis of MDA-MB-231 breast cancer cells via inhibiting STAT3-IL-6 signaling path. Our new herbal formula, SH003, mixed extract from Astragalus membranaceus, Angelica gigas, and Trichosanthes kirilowii Maximowicz, suppressed MDA-MB-231 tumor growth and lung metastasis in vivo and reduced the viability and metastatic abilities of MDA-MB-231 cells in vitro. Furthermore, SH003 inhibited STAT3 activation, which resulted in a reduction of IL-6 production. Therefore, we conclude that SH003 suppresses highly metastatic breast cancer growth and metastasis by inhibiting STAT3-IL-6 signaling path. PMID:24976685

  2. Activation of Stat3 preassembled with platelet-derived growth factor ? receptors requires Src kinase activity

    Microsoft Academic Search

    Yi-Zhe Wang; Walker Wharton; Roy Garcia; Alan Kraker; Richard Jove; W J Pledger

    2000-01-01

    Members of the STAT family of transcriptional regulators modulate the expression of a variety of gene products that promote cell proliferation, survival and transformation. Although initially identified as mediators of cytokine signaling, the STAT proteins are also activated by, and thus may contribute to the actions of, polypeptide growth factors. To define the mechanism by which these factors activate STATs,

  3. Autosomal Dominant STAT3 Deficiency and Hyper-IgE Syndrome Molecular, Cellular, and Clinical Features From a French National Survey

    PubMed Central

    Chandesris, Marie-Olivia; Melki, Isabelle; Natividad, Angels; Puel, Anne; Fieschi, Claire; Yun, Ling; Thumerelle, Caroline; Oksenhendler, Eric; Boutboul, David; Thomas, Caroline; Hoarau, Cyrille; Lebranchu, Yvon; Stephan, Jean-Louis; Cazorla, Celine; Aladjidi, Nathalie; Micheau, Marguerite; Tron, Fran[cedil]cois; Baruchel, Andre; Barlogis, Vincent; Palenzuela, Gilles; Mathey, Catherine; Dominique, Stephane; Body, Gerard; Munzer, Martine; Fouyssac, Fanny; Jaussaud, Rolland; Bader-Meunier, Brigitte; Mahlaoui, Nizar; Blanche, Stephane; Debre, Marianne; Le Bourgeois, Muriel; Gandemer, Virginie; Lambert, Nathalie; Grandin, Virginie; Ndaga, Stephanie; Jacques, Corinne; Harre, Chantal; Forveille, Monique; Alyanakian, Marie-Alexandra; Durandy, Anne; Bodemer, Christine; Suarez, Felipe; Hermine, Olivier; Lortholary, Olivier; Casanova, Jean-Laurent; Fischer, Alain; Picard, Capucine

    2013-01-01

    Autosomal dominant deficiency of signal transducer and activator of transcription 3 (STAT3) is the main genetic etiology of hyper-immunoglobulin (Ig) E syndrome. We documented the molecular, cellular, and clinical features of 60 patients with heterozygous STAT3 mutations from 47 kindreds followed in France. We identified 11 known and 13 new mutations of STAT3. Low levels of interleukin (IL)-6-dependent phosphorylation and nuclear translocation (or accumulation) of STAT3 were observed in Epstein-Barr virus-transformed B lymphocytes (EBV-B cells) from all STAT3-deficient patients tested. The immunologic phenotype was characterized by high serum IgE levels (96% of the patients), memory B-cell lymphopenia (94.5%), and hypereosinophilia (80%). A low proportion of IL-17A-producing circulating T cells was found in 14 of the 15 patients tested. Mucocutaneous infections were the most frequent, typically caused by Staphylococcus aureus (all patients) and Candida albicans (85%). Up to 90% of the patients had pneumonia, mostly caused by Staph. aureus (31%) or Streptococcus pneumoniae (30%). Recurrent pneumonia was associated with secondary bronchiectasis and pneumatocele (67%), as well as secondary aspergillosis (22%). Up to 92% of the patients had dermatitis and connective tissue abnormalities, with facial dysmorphism (95%), retention of decidual teeth (65%), osteopenia (50%), and hyperextensibility (50%). Four patients developed non-Hodgkin lymphoma. The clinical outcome was favorable, with 56 patients, including 43 adults, still alive at the end of study (mean age, 21 yr; range, 1 mo to 46 yr). Only 4 patients died, 3 from severe bacterial infection (aged 1, 15, and 29 yr, respectively). Antibiotic prophylaxis (90% of patients), antifungal prophylaxis (50%), and IgG infusions (53%) improved patient health, as demonstrated by the large decrease in pneumonia recurrence. Overall, the prognosis of STAT3 deficiency may be considered good, provided that multiple prophylactic measures, including IgG infusions, are implemented. PMID:22751495

  4. Astrocytic TLR4 expression and LPS-induced nuclear translocation of STAT3 in the sensory circumventricular organs of adult mouse brain.

    PubMed

    Nakano, Yousuke; Furube, Eriko; Morita, Shoko; Wanaka, Akio; Nakashima, Toshihiro; Miyata, Seiji

    2015-01-15

    The sensory circumventricular organs (CVOs) comprise the organum vasculosum of the lamina terminalis (OVLT), subfornical organ (SFO), and area postrema (AP) and lack the blood-brain barrier. The expression of Toll-like receptor 4 (TLR4) was seen at astrocytes throughout the sensory CVOs and at microglia in the AP and solitary nucleus around the central canal. The peripheral and central administration of lipopolysaccharide induced a similar pattern of nuclear translocation of STAT3. A microglia inhibitor minocycline largely suppressed lipopolysaccharide-induced astrocytic nuclear translocation of STAT3 in the OVLT and AP, but its effect was less in the SFO. PMID:25595264

  5. The traditional Chinese medicinal formula BDL301 suppresses tumor growth by inhibiting STAT3 pathway and inducing apoptosis in colorectal cancer cells.

    PubMed

    Chu, Li; Zhao, Huaxin; Fang, Juemin; Li, Chunyan; Liu, Zhuqing; Cui, Ran; Hu, Fei; Zhang, Xi; Chen, Yijing; Han, Hui; Cao, Chuanhai; Xu, Qing

    2015-03-01

    The traditional Chinese medicinal formula BDL301 has been used to inhibit inflammation for hundreds of years. The development of colorectal cancer and chronic inflammation are closely related. In this study, we investigated whether BDL301 could inhibit tumor growth. We found that angiogenesis and tumor growth were both inhibited in vivo. In addition, apoptosis was induced and the signal transducer and activator of transcription-3 (STAT3) pathway were suppressed in the colorectal cancer cells in vitro and in vivo by BDL301. This study demonstrates that BDL301 exerted significant anticancer activity by inhibiting the STAT3 pathways and inducing apoptosis in colorectal cancer cells. PMID:25607688

  6. Quinolone-indolone conjugate induces apoptosis by inhibiting the EGFR-STAT3-HK2 pathway in human cancer cells.

    PubMed

    Liu, Ying-Hua; Wei, Xiao-Li; Hu, Guo-Qiang; Wang, Tian-Xiao

    2015-08-01

    The epidermal growth factor receptor (EGFR) is involved in the proliferation of human tumors and is an effective target for the treatment of cancer. In the present study, a novel quinolone?indolone conjugate, QIC1 [9?Fluoro?3,7?dihydro?3?methyl?10? (4?methyl ?1?piperazinyl) ?6?(2?oxo?1,2?dihydro?indol?3?ylidenemethyl) ?7?oxo?2H?(1,4) oxazino(2,3,4?ij)quinoline], which targeted EGFR, was synthesized in order to investigate the anticancer activity and the potential mechanisms underlying the effect of this compound in human cancer cells. Using MTT assays it was observed that QIC1 inhibited the growth of HepG2 human hepatoma cells, MCF7 human breast cancer cells, HeLa human cervical cancer cells and A549 human lung adenocarcinoma cells. QIC1 arrested cell cycle progression at the G2/M phase in HepG2 cells. QIC1 inhibited the synthesis of DNA in A549 cells. In addition, it resulted in cell apoptosis, in association with increased expression of Bax and reduced expression of Bcl?2. Further analyses demonstrated that QIC1 attenuated the activity of EGFR, and the downstream signal transducer and activator of transcription 3 (STAT3)?mediated hexokinase II (HK2) signaling pathways. Furthermore, QIC1 exhibited antiproliferative effects in MCF7/DOX human doxorubicin?resistant breast cancer cells and also enhanced the anticancer activity of doxorubicin in these cells. In conclusion, the inhibition of proliferation and the induction of apoptosis was associated with reduced expression of phospho?EGFR?phospho?STAT3?HK2. The present results suggest a potential role for QIC1 in the treatment of human cancer. PMID:25937091

  7. MICRO-RNA146B PROMOTES ALVEOLAR PROGENITOR CELL MAINTENANCE THROUGH PREFERENTIAL REGULATION OF STAT3B

    E-print Network

    Elsarraj, Hanan Sataa

    2012-08-31

    , our laboratory isolated distinct ductal, alveolar and multipotent mammary progenitors by single-cell cloning of the COMMA-D (CD) cell line. Molecular characterization of the distinct clones showed significantly higher expression of miR146b in the CD...

  8. RFX-1-dependent activation of SHP-1 inhibits STAT3 signaling in hepatocellular carcinoma cells.

    PubMed

    Su, Jung-Chen; Chiang, Heng-Chieh; Tseng, Ping-Hui; Tai, Wei-Tien; Hsu, Cheng-Yi; Li, Yong-Shi; Huang, Jui-Wen; Ko, Ching-Huai; Lin, Mai-Wei; Chu, Pei-Yi; Liu, Chun-Yu; Chen, Kuen-Feng; Shiau, Chung-Wai

    2014-12-01

    Regulatory factor X-1 (RFX-1) is a transcription factor that has been linked to negative regulation of tumor progression; however, its biological function and signaling cascades are unknown. Here, we performed several studies to elucidate the roles of RFX-1 in the regulation of SHP-1 in hepatocellular carcinoma (HCC) cells. Overexpression of RFX-1 resulted in the activation of SHP-1 and repressed colony formation of HCC cells. In addition, by a mouse xenograft model, we demonstrated that RFX-1 overexpression also inhibited the tumor growth of HCC cells in vivo, suggesting that RFX-1 is of potential interest for small-molecule-targeted therapy. We also found that SC-2001, a bipyrrole molecule, induced apoptosis in HCC cells through activating RFX-1 expression. SC-2001 induced RFX-1 translocation from the cytosol to nucleus, bound to the SHP-1 promoter, and activated SHP-1 transcription. In a xenograft model, knockdown of RFX-1 reversed the antitumor effect of SC-2001. Notably, SC-2001 is much more potent than sorafenib, a clinically approved drug for HCC, in in vitro and in vivo assays. Our study confirmed that RFX-1 acts as a tumor suppressor in HCC and might be a new target for HCC therapy. The findings of this study also provide a new lead compound for targeted therapy via the activation of the RFX-1/SHP-1 pathway. PMID:25322871

  9. Resistin and interleukin-6 exhibit racially-disparate expression in breast cancer patients, display molecular association and promote growth and aggressiveness of tumor cells through STAT3 activation.

    PubMed

    Deshmukh, Sachin K; Srivastava, Sanjeev K; Bhardwaj, Arun; Singh, Ajay P; Tyagi, Nikhil; Marimuthu, Saravanakumar; Dyess, Donna L; Dal Zotto, Valeria; Carter, James E; Singh, Seema

    2015-05-10

    African-American (AA) women with breast cancer (BC) are diagnosed with more aggressive disease, have higher risk of recurrence and poorer prognosis as compared to Caucasian American (CA) women. Therefore, it is imperative to define the factors associated with such disparities to reduce the unequal burden of cancer. Emerging data suggest that inherent differences exist in the tumor microenvironment of AA and CA BC patients, however, its molecular bases and functional impact have remained poorly understood. Here, we conducted cytokine profiling in serum samples from AA and CA BC patients and identified resistin and IL-6 to be the most differentially-expressed cytokines with relative greater expression in AA patients. Resistin and IL-6 exhibited positive correlation in serum levels and treatment of BC cells with resistin led to enhanced production of IL-6. Moreover, resistin also enhanced the expression and phosphorylation of STAT3, and treatment of BC cells with IL-6-neutralizing antibody prior to resistin stimulation abolished STAT3 phosphorylation. In addition, resistin promoted growth and aggressiveness of BC cells, and these effects were mediated through STAT3 activation. Together, these findings suggest a crucial role of resistin, IL-6 and STAT3 in BC racial disparity. PMID:25868978

  10. STAT3 activity is necessary and sufficient for the development of immune-mediated myocarditis in mice and promotes progression to dilated cardiomyopathy

    PubMed Central

    Camporeale, Annalisa; Marino, Francesca; Papageorgiou, Anna; Carai, Paolo; Fornero, Sara; Fletcher, Steven; Page, Brent D G; Gunning, Patrick; Forni, Marco; Chiarle, Roberto; Morello, Mara; Jensen, Ole; Levi, Renzo; Heymans, Stephane; Poli, Valeria

    2013-01-01

    Myocarditis, often triggered by viral infection, may lead to heart auto-immunity and dilated cardiomyopathy. What determines the switch between disease resolution and progression is however incompletely understood. We show that pharmacological inhibition of STAT3, the main mediator of IL-6 signalling and of Th17-cell differentiation, protects mice from the development of Experimental Auto-immune Myocarditis reducing liver production of the complement component C3, and can act therapeutically when administered at disease peak. Further, we demonstrate that STAT3 is sufficient when constitutively active for triggering the onset of immune-mediated myocarditis, involving enhanced complement C3 production and IL-6 signalling amplification in the liver. Disease development can be prevented by C3 depletion and IL-6 receptor neutralization. This appears to be relevant to disease pathogenesis in humans, since acute myocarditis patients display significantly elevated circulating IL-6 and C3 levels and activated heart STAT3. Thus, aberrant IL-6/STAT3-mediated induction of liver acute phase response genes including C3, which occurs as a consequence of pre-existing inflammatory conditions, might represent an important factor determining the degree of myocarditis and its clinical outcome. PMID:23460527

  11. Initial interrogation, confirmation and fine mapping of modifying genes: STAT3, IL1B and IFNGR1 determine cystic fibrosis disease manifestation

    PubMed Central

    Labenski, Heike; Hedtfeld, Silke; Becker, Tim; Tümmler, Burkhard; Stanke, Frauke

    2011-01-01

    We have used a stepwise approach consisting of initial interrogation, confirmation and fine mapping to analyze STAT3, IL1B and IFNGR1 as modifiers of cystic fibrosis disease building upon the data and sample collection of the European Cystic Fibrosis Twin and Sibling Study. We have observed direct correlation between the length of the intronic microsatellite STAT3Sat to STAT3 expression levels among F508del-CFTR homozygous patients (P=0.0075), and an association of longer STAT3Sat-alleles with the presence of CFTR-mediated residual chloride secretion (P=0.0031), measured as the manifestation of the CF basic defect in intestinal tissue. Both, family-based analysis by TDT and case-reference comparison identified consistently the same intragenic IL1B haplotype as a risk variant (Praw=0.055 for TDT, Praw<0.3 for case-reference comparison). Using haplotype-guided hierarchical fine mapping, we have identified two single nucleotide exchanges for which concordant and discordant sibling pairs differ at a 7?kb – spanning core haplotype in IFNGR1 (Praw=0.0113). Taken together, our findings imply that immunorelevant pathways and ion secretion, dominated by CFTR in intestinal and respiratory epithelium, merge at the level of the epithelial cell to integrate the signaling of cytokines due to innate and acquired immune defense. PMID:21731057

  12. Curcumin Blocks Small Cell Lung Cancer Cells Migration, Invasion, Angiogenesis, Cell Cycle and Neoplasia through Janus Kinase-STAT3 Signalling Pathway

    Microsoft Academic Search

    Cheng-Liang Yang; Yong-Yu Liu; Ye-Gang Ma; Yi-Xue Xue; De-Gui Liu; Yi Ren; Xiao-Bai Liu; Yao Li; Zhen Li

    2012-01-01

    Curcumin, the active component of turmeric, has been shown to protect against carcinogenesis and prevent tumor development. However, little is known about its anti-tumor mechanism in small cell lung cancer (SCLC). In this study, we found that curcumin can inhibit SCLC cell proliferation, cell cycle, migration, invasion and angiogenesis through suppression of the STAT3. SCLC cells were treated with curcumin

  13. A sorafenib derivative and novel SHP-1 agonist, SC-59, acts synergistically with radiotherapy in hepatocellular carcinoma cells through inhibition of STAT3.

    PubMed

    Huang, Chao-Yuan; Tai, Wei-Tien; Hsieh, Chi-Ying; Hsu, Wan-Mai; Lai, Ying-Jiun; Chen, Li-Ju; Shiau, Chung-Wai; Chen, Kuen-Feng

    2014-07-28

    Radiotherapy shows limited benefit as treatment for hepatocellular carcinoma (HCC). In this study, we aimed to overcome the radioresistance of HCC by using a novel sorafenib derivative, SC-59 that targets SHP-1-related signaling. HCC cell lines (SK-Hep1, Hep3B, and Huh7) were treated with sorafenib, SC-59, radiation, sorafenib plus radiation, or SC-59 plus radiation, and then apoptosis, colony formation, signal transduction and the phosphatase activity were analyzed. The synergistic effect of radiotherapy and SC-59 was analyzed using a combination index (CI) approach. In vivo efficacy was determined in a Huh7-bearing subcutaneous model. Mice were treated with radiation (5 Gy, one fraction per day) for 4 days, SC-59 (10mg/kg/day) for 24 days, or a combination. Tumor samples were further analyzed for p-STAT3 and SHP-1 activity. SC-59 displayed a better synergistic effect when used in combination with radiotherapy than sorafenib in HCC cell lines. SC-59 downregulated p-STAT3 and its downstream targets and increased SHP-1 phosphatase activity. Both ectopic STAT3 and inhibition of SHP-1 abolished SC-59-induced radiosensitization. Moreover, SC-59 significantly synergized radiotherapy in a Huh7 xenograft model by targeting SHP-1/STAT3 signaling. The novel sorafenib derivative, SC-59, acting as a SHP-1 agonist, displays a better synergistic effect when used in combination with radiotherapy than sorafenib for the treatment of HCC. Further clinical investigation is warranted. PMID:24735751

  14. SMND-309, a novel derivative of salvianolic acid B, protects rat brains ischemia and reperfusion injury by targeting the JAK2/STAT3 pathway.

    PubMed

    Zhu, Haibo; Zou, Libo; Tian, Jingwei; Du, Guangying; Gao, Yubai

    2013-08-15

    SMND-309 is a novel derivative of salvianolic acid B, and has shown protective effects against rat cortical neuron damage in vitro and in vivo. However the molecular mechanisms through which SMND-309 affords this protection are unclear. The present study aimed to investigate the mechanisms associated with the protective activities of SMND-309 in a cerebral ischemia and reperfusion injury rat model. In this study, we used AG490, a specific inhibitor of the signaling pathway involving the Janus Kinase 2 (JAK2)/Signal Transducers and Activators of Transcription 3 (STAT3) signaling molecules and suramin, a potent inhibitor of vascular endothelial growth factor (VEGF), to investigate the mechanisms of SMND-309. The cerebral ischemia and reperfusion injury model was induced by performing middle cerebral artery occlusion (MCAO) in the rats. SMND-309 mitigated the effects of ischemia and reperfusion injury on brain by decreasing the infract volume, improving neurological function, increasing the survival of neurons and promoting angiogenesis by increasing the levels of erythropoietin (EPO), erythropoietin receptor (EPOR), phosphorylated JAK2 (P-JAK2), phosphorylated STAT3 (P-STAT3), VEGF and VEGF receptor 2 (Flk-1) in the brain. Our results suggest that SMND-309 provides significant neuroprotective effects against cerebral ischemia and reperfusion injury. The mechanisms of this protection may be attributed to the increased VEGF expression occurring from the JAK2/STAT3 pathway, activated by the increased EPO/EPOR expression in the brain. PMID:23764464

  15. Resistin and interleukin-6 exhibit racially-disparate expression in breast cancer patients, display molecular association and promote growth and aggressiveness of tumor cells through STAT3 activation

    PubMed Central

    Bhardwaj, Arun; Singh, Ajay P.; Tyagi, Nikhil; Marimuthu, Saravanakumar; Dyess, Donna L.; Zotto, Valeria Dal; Carter, James E.; Singh, Seema

    2015-01-01

    African-American (AA) women with breast cancer (BC) are diagnosed with more aggressive disease, have higher risk of recurrence and poorer prognosis as compared to Caucasian American (CA) women. Therefore, it is imperative to define the factors associated with such disparities to reduce the unequal burden of cancer. Emerging data suggest that inherent differences exist in the tumor microenvironment of AA and CA BC patients, however, its molecular bases and functional impact have remained poorly understood. Here, we conducted cytokine profiling in serum samples from AA and CA BC patients and identified resistin and IL-6 to be the most differentially-expressed cytokines with relative greater expression in AA patients. Resistin and IL-6 exhibited positive correlation in serum levels and treatment of BC cells with resistin led to enhanced production of IL-6. Moreover, resistin also enhanced the expression and phosphorylation of STAT3, and treatment of BC cells with IL-6-neutralizing antibody prior to resistin stimulation abolished STAT3 phosphorylation. In addition, resistin promoted growth and aggressiveness of BC cells, and these effects were mediated through STAT3 activation. Together, these findings suggest a crucial role of resistin, IL-6 and STAT3 in BC racial disparity. PMID:25868978

  16. Anti-angiogenic activity of thienopyridine derivative LCB03-0110 by targeting VEGFR-2 and JAK/STAT3 Signalling.

    PubMed

    Kim, Byung-Hak; Lee, Yoonji; Yoo, Hyun; Cui, Minghua; Lee, Sungwoon; Kim, Sun Young; Cho, Jong Un; Lee, Hyangsook; Yang, Beom-Seok; Kwon, Young-Guen; Choi, Sun; Kim, Tae-Yoon

    2015-07-01

    Vascular endothelial growth factor receptor-2 (VEGFR-2) and Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) signalling are important for tumor angiogenesis and metastasis. In this study, we identified (3-(2-(3-(morpholinomethyl)phenyl)thieno[3,2-b]pyridin-7-ylamino)phenol (LCB03-0110) as a potent angiogenesis inhibitor. LCB03-0110 inhibited VEGFR-2 and JAK/STAT3 signalling in primary cultured human endothelial cells and cancer cells. An in vitro kinase assay and molecular modelling revealed that LCB03-0110 inhibited VEGFR-2, c-SRC and TIE-2 kinase activity via preferential binding at the ATP-binding site of their kinases. LCB03-0110 successfully occupied the hydrophobic pocket of VEGFR-2, c-SRC and TIE-2. LCB03-0110 also inhibited hypoxia-induced HIF/STAT3 and EGF- or angiopoietin-induced signalling cascades. In addition, LCB03-0110 inhibited VEGF-induced proliferation, viability, migration and capillary-like tube formation. LCB03-0110 also suppressed the sprouting of endothelial cells in the rat aorta and the formation of new blood vessels in the mouse Matrigel plug assay, but also suppressed pulmonary metastasis and tumor xenograft in mice. Our results suggest that LCB03-0110 is a potential candidate small molecule for blocking angiogenesis mediated by aberrant activation of VEGFR-2 and JAK/STAT3 signalling. PMID:25808463

  17. Inhibition of ?-Catenin signaling suppresses pancreatic tumor growth by disrupting nuclear ?-Catenin/TCF-1 complex: Critical role of STAT-3

    PubMed Central

    Pramanik, Kartick C.; Fofaria, Neel M.; Gupta, Parul; Ranjan, Alok; Kim, Sung-Hoon; Srivastava, Sanjay K.

    2015-01-01

    Aberrant activation of ?-catenin/TCF signaling is related to the invasiveness of pancreatic cancer. In the present study, we evaluated the effect of capsaicin on ?-catenin/TCF signaling. In a concentration and time-dependent study, we observed that capsaicin treatment inhibits the activation of dishevelled (Dsh) protein DvI-1 in L3.6PL, PanC-1 and MiaPaCa-2 pancreatic cancer cells. Capsaicin treatment induced GSK-3? by inhibiting its phosphorylation and further activated APC and Axin multicomplex, leading to the proteasomal degradation of ?-catenin. Expression of TCF-1 and ?-catenin-responsive proteins, c-Myc and cyclin D1 also decreased in response to capsaicin treatment. Pre-treatment of cells with MG-132 blocked capsaicin-mediated proteasomal degradation of ?-catenin. To establish the involvement of ?-catenin in capsaicin-induced apoptosis, cells were treated with LiCl or SB415286, inhibitors of GSK-3?. Our results reveal that capsaicin treatment suppressed LiCl or SB415286-mediated activation of ?-catenin signaling. Our results further showed that capsaicin blocked nuclear translocation of ?-catenin, TCF-1 and p-STAT-3 (Tyr705). The immunoprecipitation results indicated that capsaicin treatment reduced the interaction of ?-catenin and TCF-1 in the nucleus. Moreover, capsaicin treatment significantly decreased the phosphorylation of STAT-3 at Tyr705. Interestingly, STAT-3 over expression or STAT-3 activation by IL-6, significantly increased the levels of ?-catenin and attenuated the effects of capsaicin in inhibiting ?-catenin signaling. Finally, capsaicin mediated inhibition of orthotopic tumor growth was associated with inhibition of ?-catenin/TCF-1 signaling. Taken together, our results suggest that capsaicin-induced apoptosis in pancreatic cancer cells was associated with inhibition of ?-catenin signaling due to the dissociation of ?-catenin/TCF-1 complex and the process was orchestrated by STAT-3. PMID:25869100

  18. Oral administration of penta-O-galloyl-?-D-glucose suppresses triple-negative breast cancer xenograft growth and metastasis in strong association with JAK1-STAT3 inhibition.

    PubMed

    Lee, Hyo-Jeong; Seo, Nam-Jun; Jeong, Soo-Jin; Park, Yongjin; Jung, Deok-Beom; Koh, Wonil; Lee, Hyo-Jung; Lee, Eun-Ok; Ahn, Kwang Seok; Ahn, Kyoo Seok; Lü, Junxuan; Kim, Sung-Hoon

    2011-06-01

    There is an urgent clinical need for chemotherapeutic and chemopreventive drugs for triple-negative breast cancer (TNBCa). Extending on our recent work, we hypothesize that the herbal compound 1,2,3,4,6-penta-O-galloyl-beta-D-glucose (PGG) can inhibit the growth and metastasis of TNBCa xenograft and target Janus-activated kinase (JAK)-signal transducer and activator of transcription (STAT) 3-signaling axis. Daily oral gavage of 10 mg PGG/kg body wt decreased MDA-MB-231 xenograft weight by 49.3% (P < 0.01) at 40 days postinoculation, whereas weekly intraperitoneal injections of Taxol at the same dosage resulted in a 21.4% reduction (P > 0.1). PGG treatment also decreased the incidence of lung metastasis. Immunohistochemical staining detected decreased Ki-67 (proliferation) index and increased terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling (apoptosis) index in PGG-treated and Taxol-treated xenografts. However, the CD34 (angiogenesis) index was decreased only in PGG-treated xenografts along with decreased phospho-STAT3. In cell culture of MDA-MB-231 cells, PGG decreased pSTAT3 and its downstream target proteins, decreased its upstream kinase pJAK1 and induced the expression of SHP1, a JAK1 upstream tyrosine phosphatase, within as early as 1 h of exposure. The phosphatase inhibitor pervanadate reversed the PGG-induced downregulation of pSTAT3 and caspase activation. Orally administered PGG can inhibit TNBCa growth and metastasis, probably through anti-angiogenesis, antiproliferation and apoptosis induction. Mechanistically, PGG-induced inhibition of JAK1-STAT3 axis may contribute to the observed in vivo efficacy and the effects on the cellular processes. PMID:21289371

  19. Inhibition of ?-catenin signaling suppresses pancreatic tumor growth by disrupting nuclear ?-catenin/TCF-1 complex: critical role of STAT-3.

    PubMed

    Pramanik, Kartick C; Fofaria, Neel M; Gupta, Parul; Ranjan, Alok; Kim, Sung-Hoon; Srivastava, Sanjay K

    2015-05-10

    Aberrant activation of ?-catenin/TCF signaling is related to the invasiveness of pancreatic cancer. In the present study, we evaluated the effect of capsaicin on ?-catenin/TCF signaling. In a concentration and time-dependent study, we observed that capsaicin treatment inhibits the activation of dishevelled (Dsh) protein DvI-1 in L3.6PL, PanC-1 and MiaPaCa-2 pancreatic cancer cells. Capsaicin treatment induced GSK-3? by inhibiting its phosphorylation and further activated APC and Axin multicomplex, leading to the proteasomal degradation of ?-catenin. Expression of TCF-1 and ?-catenin-responsive proteins, c-Myc and cyclin D1 also decreased in response to capsaicin treatment. Pre-treatment of cells with MG-132 blocked capsaicin-mediated proteasomal degradation of ?-catenin. To establish the involvement of ?-catenin in capsaicin-induced apoptosis, cells were treated with LiCl or SB415286, inhibitors of GSK-3?. Our results reveal that capsaicin treatment suppressed LiCl or SB415286-mediated activation of ?-catenin signaling. Our results further showed that capsaicin blocked nuclear translocation of ?-catenin, TCF-1 and p-STAT-3 (Tyr705). The immunoprecipitation results indicated that capsaicin treatment reduced the interaction of ?-catenin and TCF-1 in the nucleus. Moreover, c