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Sample records for activated stat3 pias3

  1. SHP2, SOCS3 and PIAS3 Expression Patterns in Medulloblastomas: Relevance to STAT3 Activation and Resveratrol-Suppressed STAT3 Signaling

    PubMed Central

    Li, Cong; Li, Hong; Zhang, Peng; Yu, Li-Jun; Huang, Tian-Miao; Song, Xue; Kong, Qing-You; Dong, Jian-Li; Li, Pei-Nan; Liu, Jia

    2016-01-01

    Background: Activated STAT3 signaling is critical for human medulloblastoma cells. SHP2, SOCS3 and PIAS3 are known as the negative regulators of STAT3 signaling, while their relevance to frequent STAT3 activation in medulloblastomas remains unknown. Methods: Tissue microarrays were constructed with 17 tumor-surrounding noncancerous brain tissues and 61 cases of the classic medulloblastomas, 44 the large-cell medulloblastomas, and 15 nodular medulloblastomas, which were used for immunohistochemical profiling of STAT3, SHP2, SOCS3 and PIAS3 expression patterns and the frequencies of STAT3 nuclear translocation. Three human medulloblastoma cell lines (Daoy, UW228-2 and UW228-3) were cultured with and without 100 μM resveratrol supplementation. The influences of resveratrol in SHP2, SOCS3 and PIAS3 expression and SOCS3 knockdown in STAT3 activation were analyzed using multiple experimental approaches. Results: SHP2, SOCS3 and PIAS3 levels are reduced in medulloblastomas in vivo and in vitro, of which PIAS3 downregulation is more reversely correlated with STAT3 activation. In resveratrol-suppressed medulloblastoma cells with STAT3 downregulation and decreased incidence of STAT3 nuclear translocation, PIAS3 is upregulated, the SHP2 level remains unchanged and SOCS3 is downregulated. SOCS3 proteins are accumulated in the distal ends of axon-like processes of resveratrol-differentiated medulloblastoma cells. Knockdown of SOCS3 expression by siRNA neither influences cell proliferation nor STAT3 activation or resveratrol sensitivity but inhibits resveratrol-induced axon-like process formation. Conclusion: Our results suggest that (1) the overall reduction of SHP2, SOCS3 and PIAS3 in medulloblastoma tissues and cell lines; (2) the more inverse relevance of PIAS3 expression with STAT3 activation; (3) the favorable prognostic values of PIAS3 for medulloblastomas and (4) the involvement of SOCS3 in resveratrol-promoted axon regeneration of medulloblastoma cells. PMID:28035977

  2. Protein inhibitor of activated STAT3 (PIAS3) protein promotes SUMOylation and nuclear sequestration of the intracellular domain of ErbB4 protein.

    PubMed

    Sundvall, Maria; Korhonen, Anna; Vaparanta, Katri; Anckar, Julius; Halkilahti, Kalle; Salah, Zaidoun; Aqeilan, Rami I; Palvimo, Jorma J; Sistonen, Lea; Elenius, Klaus

    2012-06-29

    ErbB4 is a receptor tyrosine kinase implicated in the development and homeostasis of the heart, central nervous system, and mammary gland. Cleavable isoforms of ErbB4 release a soluble intracellular domain (ICD) that can translocate to the nucleus and function as a transcriptional coregulator. In search of regulatory mechanisms of ErbB4 ICD function, we identified PIAS3 as a novel interaction partner of ErbB4 ICD. In keeping with the small ubiquitin-like modifier (SUMO) E3 ligase function of protein inhibitor of activated STAT (PIAS) proteins, we showed that the ErbB4 ICD is modified by SUMO, and that PIAS3 stimulates the SUMOylation. Upon overexpression of PIAS3, the ErbB4 ICD generated from the full-length receptor accumulated into the nucleus in a manner that was dependent on the functional nuclear localization signal of ErbB4. In the nucleus, ErbB4 colocalized with PIAS3 and SUMO-1 in promyelocytic leukemia nuclear bodies, nuclear domains involved in regulation of transcription. Accordingly, PIAS3 overexpression had an effect on the transcriptional coregulatory activity of ErbB4, repressing its ability to coactivate transcription with Yes-associated protein. Finally, knockdown of PIAS3 with siRNA partially rescued the inhibitory effect of the ErbB4 ICD on differentiation of MDA-MB-468 breast cancer and HC11 mammary epithelial cells. Our findings illustrate that PIAS3 is a novel regulator of ErbB4 receptor tyrosine kinase, controlling its nuclear sequestration and function.

  3. Protein Inhibitor of Activated STAT3 (PIAS3) Protein Promotes SUMOylation and Nuclear Sequestration of the Intracellular Domain of ErbB4 Protein*

    PubMed Central

    Sundvall, Maria; Korhonen, Anna; Vaparanta, Katri; Anckar, Julius; Halkilahti, Kalle; Salah, Zaidoun; Aqeilan, Rami I.; Palvimo, Jorma J.; Sistonen, Lea; Elenius, Klaus

    2012-01-01

    ErbB4 is a receptor tyrosine kinase implicated in the development and homeostasis of the heart, central nervous system, and mammary gland. Cleavable isoforms of ErbB4 release a soluble intracellular domain (ICD) that can translocate to the nucleus and function as a transcriptional coregulator. In search of regulatory mechanisms of ErbB4 ICD function, we identified PIAS3 as a novel interaction partner of ErbB4 ICD. In keeping with the small ubiquitin-like modifier (SUMO) E3 ligase function of protein inhibitor of activated STAT (PIAS) proteins, we showed that the ErbB4 ICD is modified by SUMO, and that PIAS3 stimulates the SUMOylation. Upon overexpression of PIAS3, the ErbB4 ICD generated from the full-length receptor accumulated into the nucleus in a manner that was dependent on the functional nuclear localization signal of ErbB4. In the nucleus, ErbB4 colocalized with PIAS3 and SUMO-1 in promyelocytic leukemia nuclear bodies, nuclear domains involved in regulation of transcription. Accordingly, PIAS3 overexpression had an effect on the transcriptional coregulatory activity of ErbB4, repressing its ability to coactivate transcription with Yes-associated protein. Finally, knockdown of PIAS3 with siRNA partially rescued the inhibitory effect of the ErbB4 ICD on differentiation of MDA-MB-468 breast cancer and HC11 mammary epithelial cells. Our findings illustrate that PIAS3 is a novel regulator of ErbB4 receptor tyrosine kinase, controlling its nuclear sequestration and function. PMID:22584572

  4. TRIM8 regulates stemness in glioblastoma through PIAS3-STAT3.

    PubMed

    Zhang, Changming; Mukherjee, Subhas; Tucker-Burden, Carol; Ross, James L; Chau, Monica J; Kong, Jun; Brat, Daniel J

    2017-03-01

    Glioblastoma (GBM) is the most malignant form of primary brain tumor, and GBM stem-like cells (GSCs) contribute to the rapid growth, therapeutic resistance, and clinical recurrence of these fatal tumors. STAT3 signaling supports the maintenance and proliferation of GSCs, yet regulatory mechanisms are not completely understood. Here, we report that tri-partite motif-containing protein 8 (TRIM8) activates STAT3 signaling to maintain stemness and self-renewing capabilities of GSCs. TRIM8 (also known as 'glioblastoma-expressed ring finger protein') is expressed equally in GBM and normal brain tissues, despite its hemizygous deletion in the large majority of GBMs, and its expression is highly correlated with stem cell markers. Experimental knockdown of TRIM8 reduced GSC self-renewal and expression of SOX2, NESTIN, and p-STAT3, and promoted glial differentiation. Overexpression of TRIM8 led to higher expression of p-STAT3, c-MYC, SOX2, NESTIN, and CD133, and enhanced GSC self-renewal. We found that TRIM8 activates STAT3 by suppressing the expression of PIAS3, an inhibitor of STAT3, most likely through E3-mediated ubiquitination and proteasomal degradation. Interestingly, we also found that STAT3 activation upregulates TRIM8, providing a mechanism for normalized TRIM8 expression in the setting of hemizygous gene deletion. These data demonstrate that bidirectional TRIM8-STAT3 signaling regulates stemness in GSC.

  5. Protein inhibitor of activated STAT3 inhibits adipogenic gene expression

    SciTech Connect

    Deng Jianbei; Hua Kunjie; Caveney, Erica J.; Takahashi, Nobuyuki; Harp, Joyce B. . E-mail: jharp@unc.edu

    2006-01-20

    Protein inhibitor of activated STAT3 (PIAS3), a cytokine-induced repressor of signal transducer and activator of transcription 3 (STAT3) and a modulator of a broad array of nuclear proteins, is expressed in white adipose tissue, but its role in adipogenesis is not known. Here, we determined that PIAS3 was constitutively expressed in 3T3-L1 cells at all stages of adipogenesis. However, it translocated from the nucleus to the cytoplasm 4 days after induction of differentiation by isobutylmethylxanthine, dexamethasone, and insulin (MDI). In ob/ob mice, PIAS3 expression was increased in white adipose tissue depots compared to lean mice and was found in the cytoplasm of adipocytes. Overexpression of PIAS3 in differentiating preadipocytes, which localized primarily to the nucleus, inhibited mRNA level gene expression of adipogenic transcription factors C/EBP{alpha} and PPAR{gamma}, as well as their downstream target genes aP2 and adiponectin. PIAS3 also inhibited C/EBP{alpha} promoter activation mediated specifically by insulin, but not dexamethasone or isobutylmethylxanthine. Taken together, these data suggest that PIAS3 may play an inhibitory role in adipogenesis by modulating insulin-activated transcriptional activation events. Increased PIAS3 expression in adipose tissue may play a role in the metabolic disturbances of obesity.

  6. Protein Inhibitor of Activated STAT3 Suppresses Oxidized LDL-induced Cell Responses during Atherosclerosis in Apolipoprotein E-deficient Mice

    PubMed Central

    Wang, Rong; Zhang, Yanjin; Xu, Liran; Lin, Yan; Yang, Xiaofeng; Bai, Liang; Chen, Yulong; Zhao, Sihai; Fan, Jianglin; Cheng, Xianwu; Liu, Enqi

    2016-01-01

    Atherosclerosis is a serious public health concern. Excessive inflammatory responses of vascular cells are considered a pivotal pathogenesis mechanism underlying atherosclerosis development. It is known that Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signalling plays an important role in atherosclerosis progression. Protein inhibitor of activated STAT3 (PIAS3) is the key negative regulator of JAK/STAT3 signalling. However, its effect on atherogenesis is unknown. Here, we observed that PIAS3 levels are reduced in atherosclerotic lesions and that PIAS3 expression decreases in conjunction with increases in interleukin-6 expression and atherosclerosis severity. Oxidized low-density lipoprotein (ox-LDL), an atherogenic stimulus, reduced PIAS3 expression, an effect that may be attributed to nitric oxide synthesis upregulation. In turn, PIAS3 overexpression effectively suppressed ox-LDL-induced inflammation, lipid accumulation and vascular smooth muscle cell proliferation. These results indicate that PIAS3 is a critical repressor of atherosclerosis progression. The findings of this study have contributed to our understanding on the pathogenesis of atherosclerosis and have provided us with a potential target through which we can inhibit atherosclerosis-related cellular responses. PMID:27845432

  7. STAT3 Activities and Energy Metabolism: Dangerous Liaisons

    PubMed Central

    Camporeale, Annalisa; Demaria, Marco; Monteleone, Emanuele; Giorgi, Carlotta; Wieckowski, Mariusz R.; Pinton, Paolo; Poli, Valeria

    2014-01-01

    STAT3 mediates cytokine and growth factor receptor signalling, becoming transcriptionally active upon tyrosine 705 phosphorylation (Y-P). Constitutively Y-P STAT3 is observed in many tumors that become addicted to its activity, and STAT3 transcriptional activation is required for tumor transformation downstream of several oncogenes. We have recently demonstrated that constitutively active STAT3 drives a metabolic switch towards aerobic glycolysis through the transcriptional induction of Hif-1α and the down-regulation of mitochondrial activity, in both MEF cells expressing constitutively active STAT3 (Stat3C/C) and STAT3-addicted tumor cells. This novel metabolic function is likely involved in mediating pre-oncogenic features in the primary Stat3C/C MEFs such as resistance to apoptosis and senescence and rapid proliferation. Moreover, it strongly contributes to the ability of primary Stat3C/C MEFs to undergo malignant transformation upon spontaneous immortalization, a feature that may explain the well known causative link between STAT3 constitutive activity and tumor transformation under chronic inflammatory conditions. Taken together with the recently uncovered role of STAT3 in regulating energy metabolism from within the mitochondrion when phosphorylated on Ser 727, these data place STAT3 at the center of a hub regulating energy metabolism under different conditions, in most cases promoting cell survival, proliferation and malignant transformation even though with distinct mechanisms. PMID:25089666

  8. Activation of Hepatic STAT3 Maintains Pulmonary Defense during Endotoxemia

    PubMed Central

    Hilliard, Kristie L.; Allen, Eri; Traber, Katrina E.; Kim, Yuri; Wasserman, Gregory A.; Jones, Matthew R.; Mizgerd, Joseph P.

    2015-01-01

    Pneumonia and infection-induced sepsis are worldwide public health concerns. Both pathologies elicit systemic inflammation and induce a robust acute-phase response (APR). Although APR activation is well regarded as a hallmark of infection, the direct contributions of liver activation to pulmonary defense during sepsis remain unclear. By targeting STAT3-dependent acute-phase changes in the liver, we evaluated the role of liver STAT3 activity in promoting host defense in the context of sepsis and pneumonia. We employed a two-hit endotoxemia/pneumonia model, whereby administration of 18 h of intraperitoneal lipopolysaccharide (LPS; 5 mg/kg of body weight) was followed by intratracheal Escherichia coli (106 CFU) in wild-type mice or those lacking hepatocyte STAT3 (hepSTAT3−/−). Pneumonia alone (without endotoxemia) was effectively controlled in the absence of liver STAT3. Following endotoxemia and pneumonia, however, hepSTAT3−/− mice, with significantly reduced levels of circulating and airspace acute-phase proteins, exhibited significantly elevated lung and blood bacterial burdens and mortality. These data suggested that STAT3-dependent liver responses are necessary to promote host defense. While neither recruited airspace neutrophils nor lung injury was altered in endotoxemic hepSTAT3−/− mice, alveolar macrophage reactive oxygen species generation was significantly decreased. Additionally, bronchoalveolar lavage fluid from this group of hepSTAT3−/− mice allowed greater bacterial growth ex vivo. These results suggest that hepatic STAT3 activation promotes both cellular and humoral lung defenses. Taken together, induction of liver STAT3-dependent gene expression programs is essential to countering the deleterious consequences of sepsis on pneumonia susceptibility. PMID:26216424

  9. Inhibition of STAT3 activation by KT-18618 via the disruption of the interaction between JAK3 and STAT3.

    PubMed

    Shin, Dae-Seop; Jung, Seung Nam; Yun, Jieun; Lee, Chang Woo; Han, Dong Cho; Kim, Bumtae; Min, Yong Ki; Kang, Nam Sook; Kwon, Byoung-Mog

    2014-05-01

    The constitutive activation of STAT3 in human cancers causes the abnormal proliferation and survival of cancer cells, and thus, STAT3 is a therapeutic target of antitumor drugs. We screened a small-molecule library of 8600 synthetic compounds from the "Korea Chemical Bank" to identify inhibit STAT3 activity using a cell-based luciferase assay system. KT-18618 ((Z)-N-(4-chlorophenyl)-N-methyl-2-[1,3,3,3,-tetrafluoro-2-(thiophen-2-yl)prop-1-enyloxy]-acetamide) was selected as a novel inhibitor of the JAK/STAT3 pathway. KT-18618 inhibited STAT3 phosphorylation and the expression of STAT3-regulated genes. The inhibition of STAT3 phosphorylation led to the apoptosis of MDA-MB-468 cells. We postulated that the inhibition of the JAK family of proteins or c-Src inhibited STAT3 phosphorylation. Interestingly, the phosphorylation of these kinases was only mildly inhibited, but the phosphorylation of STAT3 was completely inhibited. This result implies that the inhibition of STAT3 phosphorylation by KT-18618 is an independent event that occurs through the phosphorylation of upstream kinases. Co-immunoprecipitation experiments revealed that KT-18618 inhibited the JAK3-STAT3 interaction. Moreover, JAK3 molecules were captured by biotinylated KT-18618, implying that KT-18618 bound to JAK3 molecules. Additionally, 1μM KT-18618 inhibited JAK3 kinase activity by approximately 28% in an in vitro kinase assay. From these results, we suggest that KT-18618 binds to JAK3 molecules and disrupts the JAK3-STAT3 interaction, which leads to the inhibition of STAT3 phosphorylation. KT-18618 is the first inhibitor of the JAK3-STAT3 interaction.

  10. Activation of epithelial STAT3 regulates intestinal homeostasis.

    PubMed

    Neufert, Clemens; Pickert, Geethanjali; Zheng, Yan; Wittkopf, Nadine; Warntjen, Moritz; Nikolaev, Alexei; Ouyang, Wenjun; Neurath, Markus F; Becker, Christoph

    2010-02-15

    The intestinal epithelium that lines the mucosal surface along the GI-tract is a key player for the intestinal homeostasis of the healthy individual. In case of a mucosal damage or a barrier defect as seen in patients with inflammatory bowel disease, the balance is disturbed, and translocation of intestinal microbes to the submucosa is facilitated. We recently demonstrated a pivotal role of STAT3 activation in intestinal epithelial cells (IEC) for the restoration of the balance at the mucosal surface of the gut in an experimental colitis model. STAT3 was rapidly induced in intestinal epithelial cells upon challenge of mice in both experimental colitis and intestinal wound healing models. STAT3 activation was found to be dispensable in the steady-state conditions but was important for efficient regeneration of the epithelium in response to injury. Here, we extend our previous findings by showing epithelial STAT3 activation in human patients suffering from IBD and provide additional insights how the activation of epithelial STAT3 by IL-22 regulates intestinal homeostasis and mucosal wound healing. We also demonstrate that antibody-mediated neutralization of IL-22 has little impact on the development of experimental colitis in mice, but significantly delays recovery from colitis. Thus, our data suggest that targeting the STAT3 signaling pathway in IEC is a promising therapeutic approach in situations when the intestinal homeostasis is disturbed, e.g., as seen in Crohn's disease or Ulcerative colitis.

  11. Mutations in the linker domain affect phospho-STAT3 function and suggest targets for interrupting STAT3 activity.

    PubMed

    Mertens, Claudia; Haripal, Bhagwattie; Klinge, Sebastian; Darnell, James E

    2015-12-01

    Crystallography of the cores of phosphotyrosine-activated dimers of STAT1 (132-713) and STAT3 (127-722) bound to a similar double-stranded deoxyoligonucleotide established the domain structure of the STATs and the structural basis for activation through tyrosine phosphorylation and dimerization. We reported earlier that mutants in the linker domain of STAT1 that connect the DNA-binding domain and SH2 domain can prevent transcriptional activation. Because of the pervasive importance of persistently activated STAT3 in many human cancers and the difficulty of finding useful drug candidates aimed at disrupting the pY interchange in active STAT3 dimers, we have examined effects of an array of mutants in the STAT3 linker domain. We have found several STAT3 linker domain mutants to have profound effects of inhibiting STAT3 transcriptional activation. From these results, we propose (i) there is definite functional interaction of the linker both with the DNA binding domain and with the SH2 domain, and (ii) these putative contacts provide potential new targets for small molecule-induced pSTAT3 inhibition.

  12. Mutations in the linker domain affect phospho-STAT3 function and suggest targets for interrupting STAT3 activity

    PubMed Central

    Mertens, Claudia; Haripal, Bhagwattie; Klinge, Sebastian; Darnell, James E.

    2015-01-01

    Crystallography of the cores of phosphotyrosine-activated dimers of STAT1 (132–713) and STAT3 (127–722) bound to a similar double-stranded deoxyoligonucleotide established the domain structure of the STATs and the structural basis for activation through tyrosine phosphorylation and dimerization. We reported earlier that mutants in the linker domain of STAT1 that connect the DNA-binding domain and SH2 domain can prevent transcriptional activation. Because of the pervasive importance of persistently activated STAT3 in many human cancers and the difficulty of finding useful drug candidates aimed at disrupting the pY interchange in active STAT3 dimers, we have examined effects of an array of mutants in the STAT3 linker domain. We have found several STAT3 linker domain mutants to have profound effects of inhibiting STAT3 transcriptional activation. From these results, we propose (i) there is definite functional interaction of the linker both with the DNA binding domain and with the SH2 domain, and (ii) these putative contacts provide potential new targets for small molecule-induced pSTAT3 inhibition. PMID:26553978

  13. PIAS3 induction of PRB sumoylation represses PRB transactivation by destabilizing its retention in the nucleus

    PubMed Central

    Man, Jiang-Hong; Li, Hui-Yan; Zhang, Pei-Jing; Zhou, Tao; He, Kun; Pan, Xin; Liang, Bing; Li, Ai-Ling; Zhao, Jie; Gong, Wei-Li; Jin, Bao-Feng; Xia, Qing; Yu, Ming; Shen, Bei-Fen; Zhang, Xue-Min

    2006-01-01

    Progesterone receptor (PR) plays a critical role in cell proliferation and differentiation, and its transcriptional activity is known to be modulated by cofactor proteins. In the present study, we demonstrated that in the presence of progesterone, protein inhibitor of activated STAT-3 (PIAS3) significantly inhibited the PR transcriptional activity and the expression of progesterone-responsive genes. Reduction of endogenous PIAS3 by PIAS3 small-interfering RNA enhanced PR transactivation in a ligand-dependent manner. PIAS3 interacted with PR both in vitro and in vivo and the interaction was enhanced by progesterone. Furthermore, our findings suggested that PIAS3 strongly induced PRB sumoylation at three sites, Lys-7, Lys-388 and Lys-531. In addition, novel roles in PRB nuclear retention and transactivation were identified for these sites. Our data also suggested that PIAS3 was recruited in a largely hormone-dependent manner in response to a progesterone-responsive promoter. Finally, we demonstrated that PIAS3 inhibited the DNA-binding activity of PR and influenced its nuclear export as well as PR transactivation. Taken together, these data strongly suggested that PIAS3 played an important physiological role in PR function. PMID:17020914

  14. Resveratrol inhibits Src and Stat3 signaling and induces the apoptosis of malignant cells containing activated Stat3 protein.

    PubMed

    Kotha, Anupama; Sekharam, Madhavi; Cilenti, Lucia; Siddiquee, Khandaker; Khaled, Annette; Zervos, Antonis S; Carter, Bradford; Turkson, James; Jove, Richard

    2006-03-01

    Resveratrol is a naturally occurring phytoalexin with antioxidant and antiinflammatory properties. Recent studies suggest that resveratrol possesses anticancer effects, although its mechanism of action is not well understood. We now show that resveratrol inhibits Src tyrosine kinase activity and thereby blocks constitutive signal transducer and activator of transcription 3 (Stat3) protein activation in malignant cells. Analyses of resveratrol-treated malignant cells harboring constitutively-active Stat3 reveal irreversible cell cycle arrest of v-Src-transformed mouse fibroblasts (NIH3T3/v-Src), human breast (MDA-MB-231), pancreatic (Panc-1), and prostate carcinoma (DU145) cell lines at the G0-G1 phase or at the S phase of human breast cancer (MDA-MB-468) and pancreatic cancer (Colo-357) cells, and loss of viability due to apoptosis. By contrast, cells treated with resveratrol, but lacking aberrant Stat3 activity, show reversible growth arrest and minimal loss of viability. Moreover, in malignant cells harboring constitutively-active Stat3, including human prostate cancer DU145 cells and v-Src-transformed mouse fibroblasts (NIH3T3/v-Src), resveratrol treatment represses Stat3-regulated cyclin D1 as well as Bcl-xL and Mcl-1 genes, suggesting that the antitumor cell activity of resveratrol is in part due to the blockade of Stat3-mediated dysregulation of growth and survival pathways. Our study is among the first to identify Src-Stat3 signaling as a target of resveratrol, further defining the mechanism of antitumor cell activity of resveratrol and raising its potential application in tumors with an activated Stat3 profile.

  15. Heme Mediated STAT3 Activation in Severe Malaria

    PubMed Central

    Liu, Mingli; Amodu, Audu S.; Pitts, Sidney; Patrickson, John; Hibbert, Jacqueline M.; Battle, Monica; Ofori-Acquah, Solomon F.; Stiles, Jonathan K.

    2012-01-01

    Background The mortality of severe malaria [cerebral malaria (CM), severe malaria anemia (SMA), acute lung injury (ALI) and acute respiratory distress syndrome (ARDS)] remains high despite the availability associated with adequate treatments. Recent studies in our laboratory and others have revealed a hitherto unknown correlation between chemokine CXCL10/CXCR3, Heme/HO-1 and STAT3 and cerebral malaria severity and mortality. Although Heme/HO-1 and CXCL10/CXCR3 interactions are directly involved in the pathogenesis of CM and fatal disease, the mechanism dictating how Heme/HO-1 and CXCL10/CXCR3 are expressed and regulated under these conditions is still unknown. We therefore tested the hypothesis that these factors share common signaling pathways and may be mutually regulated. Methods We first clarified the roles of Heme/HO-1, CXCL10/CXCR3 and STAT3 in CM pathogenesis utilizing a well established experimental cerebral malaria mouse (ECM, P. berghei ANKA) model. Then, we further determined the mechanisms how STAT3 regulates HO-1 and CXCL10 as well as mutual regulation among them in CRL-2581, a murine endothelial cell line. Results The results demonstrate that (1) STAT3 is activated by P. berghei ANKA (PBA) infection in vivo and Heme in vitro. (2) Heme up-regulates HO-1 and CXCL10 production through STAT3 pathway, and regulates CXCL10 at the transcriptional level in vitro. (3) HO-1 transcription is positively regulated by CXCL10. (4) HO-1 regulates STAT3 signaling. Conclusion Our data indicate that Heme/HO-1, CXCL10/CXCR3 and STAT3 molecules as well as related signaling pathways play very important roles in the pathogenesis of severe malaria. We conclude that these factors are mutually regulated and provide new opportunities to develop potential novel therapeutic targets that could be used to supplement traditional prophylactics and treatments for malaria and improve clinical outcomes while reducing malaria mortality. Our ultimate goal is to develop novel therapies

  16. Activating STAT3 Alpha for Promoting Healing of Neurons

    NASA Technical Reports Server (NTRS)

    Conway, Greg

    2008-01-01

    A method of promoting healing of injured or diseased neurons involves pharmacological activation of the STAT3 alpha protein. Usually, injured or diseased neurons heal incompletely or not at all for two reasons: (1) they are susceptible to apoptosis (cell death); and (2) they fail to engage in axogenesis that is, they fail to re-extend their axons to their original targets (e.g., muscles or other neurons) because of insufficiency of compounds, denoted neurotrophic factors, needed to stimulate such extension. The present method (see figure) of treatment takes advantage of prior research findings to the effect that the STAT3 alpha protein has anti-apoptotic and pro-axogenic properties.

  17. CNTF protects neurons from hypoxic injury through the activation of STAT3pTyr705.

    PubMed

    Gu, Ying Li; Gao, Guan Qun; Ma, Ning; Ye, Lin Lin; Zhang, Li Wei; Gao, Xu; Zhang, Zhuo Bo

    2016-12-01

    The aim of the present study was to investigate whether ciliary neurotrophic factor (CNTF) plays its neuroprotective role following hypoxic injury through the activation of signal transducer and activator of transcription 3 (STAT3) signaling. Firstly, to determine whether CNTF exerts its effects via STAT3 following hypoxic injury, cultured neurons from the cerebral cortex of mice were prepared and a neuronal model of hypoxia was then established. The neurons exposed to hypoxia were then pre-treated with CNTF and transfected with small interference RNA (siRNA) targeting STAT3 (STAT3 siRNA) using polybrene, or with STAT3Tyr705 mutant or STAT3Ser727 mutant using an electroporation system. The survival, proliferation and neurite outgrowth of the neurons subjected to different treatments were also determined. RT-qPCR and western blot analysis were employed to examine the expression levels of STAT3, p-STAT3Tyr705 and p-STAT3Ser727 following treatment with CNTF and other treatments. Our results revealed that treatment with CNTF: i) protected neurons from hypoxic injury by promoting survival and neurite growth; ii) induced a significant increase in the levels of STAT3, STAT3pTyr705 and the STAT3pTyr705/STAT3 ratio; it did not however, significantly affect the levels of STAT3pSer727 in the hypoxic cerebral cortex neurons. Transfection of the hypoxic neurons pre-treated with CNTF with STAT3 siRNA or STAT3Tyr705 neutralized the protective effects exerted by CNTF. The findings of our study thus demonstrate that CNTF protects neurons from hypoxic injury through the activation of STAT3pTyr705.

  18. PASD1 promotes STAT3 activity and tumor growth by inhibiting TC45-mediated dephosphorylation of STAT3 in the nucleus.

    PubMed

    Xu, Zhi-Sheng; Zhang, Hong-Xia; Zhang, Yu-Long; Liu, Tian-Tian; Ran, Yong; Chen, Liu-Ting; Wang, Yan-Yi; Shu, Hong-Bing

    2016-06-01

    Activation of the transcription factor signal transducer and activator of transcription 3 (STAT3) is tightly regulated during various physiological processes, such as cell proliferation, survival, and differentiation, and aberrant STAT3 activation results in tumorigenesis. In this study, we identified the cancer/testis antigen PASD1 as a positive regulator of STAT3 activity. Overexpression of PASD1 activated STAT3 and potentiated IL-6-induced activation of STAT3, whereas knockdown of PASD1 had opposite effects. Endogenous coimmunoprecipitation experiments indicated that PASD1 interacted with STAT3 in the nucleus. Overexpression of PASD1 enhanced both basal and IL-6-induced STAT3 phosphorylation at Y705, whereas knockdown of PASD1 had opposite effects. Mechanistically, PASD1 competed with TC45, a nuclear protein tyrosine phosphatase, to associate with STAT3, thus inhibited TC45-mediated dephosphorylation of STAT3. Consistently, knockdown of PASD1 inhibited expression of many pro-oncogenic genes, leading to suppression of cell proliferation, anchorage-independent growth, cell migration, and tumor growth in nude mice. Our findings demonstrate that PASD1 serves as a critical nuclear positive regulator of STAT3-mediated gene expression and tumorigenesis.

  19. 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

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

    SciTech Connect

    Arulanandam, Rozanne; Geletu, Mulu; Feracci, Helene; Raptis, Leda

    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.

  1. LIGHT, a member of the TNF superfamily, activates Stat3 mediated by NIK pathway

    SciTech Connect

    Nadiminty, Nagalakshmi; Chun, Jae Yeon; Hu, Yan; Dutt, Smitha; Lin, Xin; Gao, Allen C. . E-mail: allen.gao@roswellpark.org

    2007-07-27

    Stat3, a member of the signal transducers and activators of transcription (STAT) family, is a key signal transduction protein activated by numerous cytokines, growth factors, and oncoproteins that controls cell proliferation, differentiation, development, survival, and inflammation. Constitutive activation of Stat3 has been found frequently in a wide variety of human tumors and induces cellular transformation and tumor formation. In this study, we demonstrated that LIGHT, a member of tumor necrosis factor superfamily, activates Stat3 in cancer cells. LIGHT induces dose-dependent activation of Stat3 by phosphorylation at both the tyrosine 705 and serine 727 residues. The activation of Stat3 by LIGHT appears to be mediated by NIK phosphorylation. Expression of a kinase-inactive NIK mutant abolished LIGHT induced Stat3 activation. Overexpression of an active NIK induces Stat3 activation by phosphorylation at the both tyrosine 705 and serine 727 residues. Activation of Stat3 by NIK requires NIK kinase activity as showed by kinase assays. In addition, LIGHT increases the expression of Stat3 target genes including cyclin D1, survivin, and Bcl-xL, and stimulates human LNCaP prostate cancer cell growth in vitro which can be blocked by expression of a dominant-negative Stat3 mutant. Taken together, these results indicate that in addition to activating NF-{kappa}B/p52, LIGHT also activates Stat3. Activation of Stat3 together with activating non-canonical NF-{kappa}B/p52 signaling by LIGHT may maximize its effects on cellular proliferation, survival, and inflammation.

  2. Epstein-Barr virus-derived EBNA2 regulates STAT3 activation

    SciTech Connect

    Muromoto, Ryuta; Ikeda, Osamu; Okabe, Kanako; Togi, Sumihito; Kamitani, Shinya; Fujimuro, Masahiro; Harada, Shizuko; Oritani, Kenji; Matsuda, Tadashi

    2009-01-16

    The Epstein-Barr virus (EBV)-encoded latency protein EBNA2 is a nuclear transcriptional activator that is essential for EBV-induced cellular transformation. Here, we show that EBNA2 interacts with STAT3, a signal transducer for an interleukin-6 family cytokine, and enhances the transcriptional activity of STAT3 by influencing its DNA-binding activity. Furthermore, EBNA2 cooperatively acts on STAT3 activation with LMP1. These data demonstrate that EBNA2 acts as a transcriptional coactivator of STAT3.

  3. High glucose enhances progression of cholangiocarcinoma cells via STAT3 activation.

    PubMed

    Saengboonmee, Charupong; Seubwai, Wunchana; Pairojkul, Chawalit; Wongkham, Sopit

    2016-01-08

    Epidemiological studies have indicated diabetes mellitus (DM) as a risk of cholangiocarcinoma (CCA), however, the effects and mechanisms of high glucose on progression of CCA remain unclear. This study reports for the first time of the enhancing effects of high glucose on aggressive phenotypes of CCA cells via STAT3 activation. CCA cells cultured in high glucose media exerted significantly higher rates of cell proliferation, adhesion, migration and invasion than those cultured in normal glucose. The phosphokinase array revealed STAT3 as the dominant signal activated in response to high glucose. Increased nuclear STAT3, p-STAT3 and its downstream target proteins, cyclin D1, vimentin and MMP2, were shown to be underling mechanisms of high glucose stimulation. The link of high glucose and STAT3 activation was confirmed in tumor tissues from CCA patients with DM that exhibited higher STAT3 activation than those without DM. Moreover, the levels of STAT3 activation were correlated with the levels of blood glucose. Finally, decreasing the level of glucose or using a STAT3 inhibitor could reduce the effects of high glucose. These findings suggest that controlling blood glucose or using a STAT3 inhibitor as an alternative approach may improve the therapeutic outcome of CCA patients with DM.

  4. 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

  5. Genomic and Transcriptomic Alterations Associated with STAT3 Activation in Head and Neck Cancer

    PubMed Central

    Peyser, Noah D.; Pendleton, Kelsey; Gooding, William E.; Lui, Vivian W. Y.; Johnson, Daniel E.; Grandis, Jennifer R.

    2016-01-01

    Background Hyperactivation of STAT3 via constitutive phosphorylation of tyrosine 705 (Y705) is common in most human cancers, including head and neck squamous carcinoma (HNSCC). STAT3 is rarely mutated in cancer and the (epi)genetic alterations that lead to STAT3 activation are incompletely understood. Here we used an unbiased approach to identify genomic and epigenomic changes associated with pSTAT3(Y705) expression using data generated by The Cancer Genome Atlas (TCGA). Methods and Findings Mutation, mRNA expression, promoter methylation, and copy number alteration data were extracted from TCGA and examined in the context of pSTAT3(Y705) protein expression. mRNA expression levels of 1279 genes were found to be associated with pSTAT3(705) expression. Association of pSTAT3(Y705) expression with caspase-8 mRNA expression was validated by immunoblot analysis in HNSCC cells. Mutation, promoter hypermethylation, and copy number alteration of any gene were not significantly associated with increased pSTAT3(Y705) protein expression. Conclusions These cumulative results suggest that unbiased approaches may be useful in identifying the molecular underpinnings of oncogenic signaling, including STAT3 activation, in HNSCC. Larger datasets will likely be necessary to elucidate signaling consequences of infrequent alterations. PMID:27855189

  6. Death-associated protein kinase controls STAT3 activity in intestinal epithelial cells.

    PubMed

    Chakilam, Saritha; Gandesiri, Muktheshwar; Rau, Tilman T; Agaimy, Abbas; Vijayalakshmi, Mahadevan; Ivanovska, Jelena; Wirtz, Ralph M; Schulze-Luehrmann, Jan; Benderska, Natalya; Wittkopf, Nadine; Chellappan, Ajithavalli; Ruemmele, Petra; Vieth, Michael; Rave-Fränk, Margret; Christiansen, Hans; Hartmann, Arndt; Neufert, Clemens; Atreya, Raja; Becker, Christoph; Steinberg, Pablo; Schneider-Stock, Regine

    2013-03-01

    The TNF-IL-6-STAT3 pathway plays a crucial role in promoting ulcerative colitis-associated carcinoma (UCC). To date, the negative regulation of STAT3 is poorly understood. Interestingly, intestinal epithelial cells of UCC in comparison to ulcerative colitis show high expression levels of anti-inflammatory death-associated protein kinase (DAPK) and low levels of pSTAT3. Accordingly, epithelial DAPK expression was enhanced in STAT3(IEC-KO) mice. To unravel a possible regulatory mechanism, we used an in vitro TNF-treated intestinal epithelial cell model. We identified a new function of DAPK in suppressing TNF-induced STAT3 activation as DAPK siRNA knockdown and treatment with a DAPK inhibitor potentiated STAT3 activation, IL-6 mRNA expression, and secretion. DAPK attenuated STAT3 activity directly by physical interaction shown in three-dimensional structural modeling. This model suggests that DAPK-induced conformational changes in the STAT3 dimer masked its nuclear localization signal. Alternatively, pharmacological inactivation of STAT3 led to an increase in DAPK mRNA and protein levels. Chromatin immunoprecipitation showed that STAT3 restricted DAPK expression by promoter binding, thereby reinforcing its own activation by inducing IL-6. This novel negative regulation principle might balance TNF-induced inflammation and seems to play an important role in the inflammation-associated transformation process as confirmed in an AOM+DSS colon carcinogenesis mouse model. DAPK as a negative regulator of STAT3 emerges as therapeutic option in the treatment of ulcerative colitis and UCC.

  7. 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; Chang, Zhijie; Wang, Jian; Yang, Xiaoming; He, Fuchu

    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.

  8. Activation of the Notch1/STAT3/Twist signaling axis promotes gastric cancer progression.

    PubMed

    Hsu, Kai-Wen; Hsieh, Rong-Hong; Huang, Kuo-Hung; Fen-Yau Li, Anna; Chi, Chin-Wen; Wang, Tzu-Yin; Tseng, Min-Jen; Wu, Kou-Juey; Yeh, Tien-Shun

    2012-08-01

    Gastric carcinoma is one of the most common malignancies and a lethal cancer in the world. Notch signaling and transcription factors STAT3 (signal transducer and activator of transcription 3) and Twist regulate tumor development and are critical regulators of gastric cancer progression. Herein, the relationship among Notch, STAT3 and Twist pathways in the control of gastric cancer progression was studied. We found that Twist and phosphorylated STAT3 levels were promoted by the activated Notch1 receptor in human stomach adenocarcinoma SC-M1, embryonic kidney HEK293 and erythroleukemia K562 cells. Notch1 signaling dramatically induced Twist promoter activity through a C promoter binding factor-1-independent manner and STAT3 phosphorylation. Overexpression of Notch1 receptor intracellular domain (N1IC) enhanced the interaction between nuclear STAT3 and Twist promoter in cells. Gastric cancer progression of SC-M1 cells was promoted by N1IC through STAT3 phosphorylation and Twist expression including colony formation, migration and invasion. STAT3 regulated gastric cancer progression of SC-M1 cells via Twist. N1IC also elevated the progression of other gastric cancer cells such as AGS and KATO III cells through STAT3 and Twist. The N1IC-promoted tumor growth and lung metastasis of SC-M1 cells in mice were suppressed by the STAT3 inhibitor JSI-124 and Twist knockdown. Furthermore, Notch1 and Notch ligand Jagged1 expressions were significantly associated with phosphorylated STAT3 and Twist levels in gastric cancer tissues of patients. Taken together, these results suggest that Notch1/STAT3/Twist signaling axis is involved in progression of human gastric cancer and modulation of this cascade has potential for the targeted combination therapy.

  9. 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/6Stat3ΔIEC, 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/ 6Stat3ΔIEC). 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

  10. At High Levels, Constitutively Activated STAT3 Induces Apoptosis of Chronic Lymphocytic Leukemia Cells.

    PubMed

    Rozovski, Uri; Harris, David M; Li, Ping; Liu, Zhiming; Wu, Ji Yuan; Grgurevic, Srdana; Faderl, Stefan; Ferrajoli, Alessandra; Wierda, William G; Martinez, Matthew; Verstovsek, Srdan; Keating, Michael J; Estrov, Zeev

    2016-05-15

    In chronic lymphocytic leukemia (CLL), the increment in PBLs is slower than the expected increment calculated from the cells' proliferation rate, suggesting that cellular proliferation and apoptosis are concurrent. Exploring this phenomenon, we found overexpression of caspase-3, higher cleaved poly (ADP-ribose) polymerase levels (p < 0.007), and a higher apoptosis rate in cells from patients with high counts compared with cells from patients with low counts. Although we previously found that STAT3 protects CLL cells from apoptosis, STAT3 levels were significantly higher in cells from patients with high counts than in cells from patients with low counts. Furthermore, overexpression of STAT3 did not protect the cells. Rather, it upregulated caspase-3 and induced apoptosis. Remarkably, putative STAT3 binding sites were identified in the caspase-3 promoter, and a luciferase assay, chromatin immunoprecipitation, and an EMSA revealed that STAT3 activated caspase-3 However, caspase-3 levels increased only when STAT3 levels were sufficiently high. Using chromatin immunoprecipitation and EMSA, we found that STAT3 binds with low affinity to the caspase-3 promoter, suggesting that at high levels, STAT3 activates proapoptotic mechanisms and induces apoptosis in CLL cells.

  11. 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)Rα 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

  12. Stat3 links activated keratinocytes and immunocytes required for development of psoriasis in a novel transgenic mouse model.

    PubMed

    Sano, Shigetoshi; Chan, Keith Syson; Carbajal, Steve; Clifford, John; Peavey, Mary; Kiguchi, Kaoru; Itami, Satoshi; Nickoloff, Brian J; DiGiovanni, John

    2005-01-01

    Here we report that epidermal keratinocytes in psoriatic lesions are characterized by activated Stat3. Transgenic mice with keratinocytes expressing a constitutively active Stat3 (K5.Stat3C mice) develop a skin phenotype either spontaneously, or in response to wounding, that closely resembles psoriasis. Keratinocytes from K5.Stat3C mice show upregulation of several molecules linked to the pathogenesis of psoriasis. In addition, the development of psoriatic lesions in K5.Stat3C mice requires cooperation between Stat3 activation in keratinocytes and activated T cells. Finally, abrogation of Stat3 function by a decoy oligonucleotide inhibits the onset and reverses established psoriatic lesions in K5.Stat3C mice. Thus, targeting Stat3 may be potentially therapeutic in the treatment of psoriasis.

  13. Endothelial STAT3 Activation Increases Vascular Leakage Through Downregulating Tight Junction Proteins: Implications for Diabetic Retinopathy.

    PubMed

    Yun, Jang-Hyuk; Park, Sung Wook; Kim, Kyung-Jin; Bae, Jong-Sup; Lee, Eun Hui; Paek, Sun Ha; Kim, Seung U; Ye, Sangkyu; Kim, Jeong-Hun; Cho, Chung-Hyun

    2017-05-01

    Vascular inflammation is characteristic feature of diabetic retinopathy. In diabetic retina, a variety of the pro-inflammatory cytokines are elevated and involved in endothelial dysfunction. STAT3 transcription factor has been implicated in mediating cytokine signaling during vascular inflammation. However, whether and how STAT3 is involved in the direct regulation of the endothelial permeability is currently undefined. Our studies revealed that IL-6-induced STAT3 activation increases retinal endothelial permeability and vascular leakage in retinas of mice through the reduced expression of the tight junction proteins ZO-1 and occludin. In a co-culture model with microglia and endothelial cells under a high glucose condition, the microglia-derived IL-6 induced STAT3 activation in the retinal endothelial cells, leading to increasing endothelial permeability. In addition, IL-6-induced STAT3 activation was independent of ROS generation in the retinal endothelial cells. Moreover, we demonstrated that STAT3 activation downregulates the ZO-1 and occludin levels and increases the endothelial permeability through the induction of VEGF production in retinal endothelial cells. These results suggest the potential importance of IL-6/STAT3 signaling in regulating endothelial permeability and provide a therapeutic target to prevent the pathology of diabetic retinopathy. J. Cell. Physiol. 232: 1123-1134, 2017. © 2016 Wiley Periodicals, Inc.

  14. JAB1 regulates unphosphorylated STAT3 DNA-binding activity through protein–protein interaction in human colon cancer cells

    SciTech Connect

    Nishimoto, Arata; Kugimiya, Naruji; Hosoyama, Toru; Enoki, Tadahiko; Li, Tao-Sheng; Hamano, Kimikazu

    2013-08-30

    Highlights: •JAB1 interacted with unphosphorylated STAT3 in the nucleus. •JAB1 knockdown tended to increase nuclear STAT3 expression. •JAB1 knockdown significantly decreased unphosphorylated STAT3 DNA-binding activity. •JAB1 knockdown significantly decreased MDR1, NANOG, and VEGF expressions. •Nuclear JAB1, but not nuclear STAT3, correlated with STAT3 DNA-binding activity. -- Abstract: Recent studies have revealed that unphosphorylated STAT3 forms a dimer, translocates to the nucleus, binds to the STAT3 binding site, and activates the transcription of STAT3 target genes, thereby playing an important role in oncogenesis in addition to phosphorylated STAT3. Among signaling steps of unphosphorylated STAT3, nuclear translocation and target DNA-binding are the critical steps for its activation. Therefore, elucidating the regulatory mechanism of these signaling steps of unphosphorylated STAT3 is a potential step in the discovery of a novel cancer drug. However, the mechanism of unphosphorylated STAT3 binding to the promoter of target genes remains unclear. In this study, we focused on Jun activation domain-binding protein 1 (JAB1) as a candidate protein that regulates unphosphorylated STAT3 DNA-binding activity. Initially, we observed that both unphosphorylated STAT3 and JAB1 existed in the nucleus of human colon cancer cell line COLO205 at the basal state (no cytokine stimulation). On the other hand, phosphorylated STAT3 did not exist in the nucleus of COLO205 cells at the basal state. Immunoprecipitation using nuclear extract of COLO205 cells revealed that JAB1 interacted with unphosphorylated STAT3. To investigate the effect of JAB1 on unphosphorylated STAT3 activity, RNAi studies were performed. Although JAB1 knockdown tended to increase nuclear STAT3 expression, it significantly decreased unphosphorylated STAT3 DNA-binding activity. Subsequently, JAB1 knockdown significantly decreased the expression levels of MDR1, NANOG, and VEGF, which are STAT3 target

  15. STAT3 activation in circulating monocytes contributes to neovascular age-related macular degeneration

    PubMed Central

    Chen, Mei; Lechner, Judith; Zhao, Jiawu; Toth, Levente; Hogg, Ruth; Silvestri, Giuliana; Kissenpfennig, Adrien; Chakravarthy, Usha; Xu, Heping

    2016-01-01

    Infiltrating macrophages are critically involved in pathogenic angiogenesis such as neovascular age-related macular degeneration (nAMD). Macrophages originate from circulating monocytes and three subtypes of monocyte exist in humans: classical (CD14+CD16-), non-classical (CD14-CD16+) and intermediate (CD14+CD16+) monocytes. The aim of this study was to investigate the role of circulating monocyte in neovascular age-related macular degeneration (nAMD). Flow cytometry analysis showed that the intermediate monocytes from nAMD patients expressed higher levels of CX3CR1 and HLA-DR compared to those from controls. Monocytes from nAMD patients expressed higher levels of phosphorylated Signal Transducer and Activator of Transcription 3 (pSTAT3), and produced higher amount of VEGF. In the mouse model of choroidal neovascularization (CNV), pSTAT3 expression was increased in the retina and RPE/choroid, and 49.24% of infiltrating macrophages express pSTAT3. Genetic deletion of the Suppressor of Cytokine Signalling 3 (SOCS3) in myeloid cells in the LysM-Cre+/-:SOCS3fl/fl mice resulted in spontaneous STAT3 activation and accelerated CNV formation. Inhibition of STAT3 activation using a small peptide LLL12 suppressed laser-induced CNV. Our results suggest that monocytes, in particular the intermediate subset of monocytes are activated in nAMD patients. STAT3 activation in circulating monocytes may contribute to the development of choroidal neovascularisation in AMD. PMID:27009107

  16. The Role of Stat3 Activation in Androgen Receptor Signaling and Prostate Cancer

    DTIC Science & Technology

    2006-07-01

    Naruto, M., and Kishimoto, T. Molecular cloning of APRF, a novel IFN-stimulated gene factor 3 p91- related transcrip- tion factor involved in the gp130...independent tumor cells. The molecular mechanism characterizing prostate cancer progression from androgen-dependence to androgenindependence is incompletely...consequence of Stat3 activation in prostate cancer cell growth and to determine the molecular basis of Stat3 interactions with androgen receptor signaling

  17. Inhibition of Stat3 activation in the endometrium prevents implantation: a nonsteroidal approach to contraception.

    PubMed

    Catalano, Rob D; Johnson, Martin H; Campbell, Elizabeth A; Charnock-Jones, D Stephen; Smith, Stephen K; Sharkey, Andrew M

    2005-06-14

    Activation of the receptors for leukemia inhibitory factor (LIF) and IL-11 is essential for embryo attachment and decidualization in mice. Both receptors induce activation of the Stat family of signal transducers via the Jak/Stat pathway. Here, we aimed to establish whether activation of Stat3 in maternal endometrium is essential for successful implantation. Functional blockade of Stat3 before implantation, by injection into the uterine lumen of a cell-permeable Stat3 peptide inhibitor, reduced embryo implantation specifically by 70% (P < 0.001). Stat3 is phosphorylated in the luminal epithelium (LE) in response to LIF, and this phosphorylation was significantly reduced both in vitro and in vivo by the Stat3 inhibitor. The inhibitor also blocked induction by LIF of several LIF-regulated genes in the LE including Irg1, which has been shown previously to be essential for implantation. Successful implantation is therefore dependent on phosphorylation and activation of Stat3 in the endometrium before implantation. This finding provides a target for contraceptive development, based on selective blockade of signal transduction pathways essential for implantation. This study demonstrates that cell-permeable peptide inhibitors can be used effectively to target intracellular signaling pathways in the uterine LE.

  18. STAT3-Activated GM-CSFRα Translocates to the Nucleus and Protects CLL Cells from Apoptosis

    PubMed Central

    Li, Ping; Harris, David; Liu, Zhiming; Rozovski, Uri; Ferrajoli, Alessandra; Wang, Yongtao; Bueso-Ramos, Carlos; Hazan-Halevy, Inbal; Grgurevic, Srdana; Wierda, William; Burger, Jan; O'Brien, Susan; Faderl, Stefan; Keating, Michael; Estrov, Zeev

    2014-01-01

    Here it was determined that Chronic Lymphocytic Leukemia (CLL) cells express the α-subunit but not the β-subunit of the granulocyte-macrophage colony-stimulating factor receptor (GM-CSFR/CSF3R). GM-CSFRα was detected on the surface, in the cytosol, and the nucleus of CLL cells via confocal microscopy, cell fractionation, and GM-CSFRα antibody epitope mapping. Because STAT3 is frequently activated in CLL and the GM-CSFRα promoter harbors putative STAT3 consensus binding sites, MM1 cells were transfected with truncated forms of the GM-CSFRα promoter, then stimulated with IL-6 to activate STAT3 to identify STAT3 binding sites. Chromatin immunoprecipitation (ChIP) and an electoromobility shift assay (EMSA) confirmed STAT3 occupancy to those promoter regions in both IL-6 stimulated MM1 and CLL cells. Transfection of MM1 cells with STAT3 siRNA or CLL cells with STAT3 shRNA significantly down-regulated GM-CSFRα mRNA and protein levels. RNA transcripts, involved in regulating cell-survival pathways, and the proteins KAP1 (TRIM28) and ISG15 co-immunoprecipitated with GM-CSFRα. GM-CSFRα-bound KAP1 enhanced the transcriptional activity of STAT3, whereas ISG15 inhibited the NF-κB pathway. Nevertheless, overexpression of GM-CSFRα protected MM1 cells from dexamethasone-induced apoptosis, and GM-CSFRα knockdown induced apoptosis in CLL cells, suggesting that GM-CSFRα provides a ligand-independent survival advantage. PMID:24836891

  19. ERp57 modulates STAT3 activity in radioresistant laryngeal cancer cells and serves as a prognostic marker for laryngeal cancer.

    PubMed

    Choe, Min Ho; Min, Joong Won; Jeon, Hong Bae; Cho, Dong-Hyung; Oh, Jeong Su; Lee, Hyun Gyu; Hwang, Sang-Gu; An, Sungkwan; Han, Young-Hoon; Kim, Jae-Sung

    2015-02-20

    Although targeting radioresistant tumor cells is essential for enhancing the efficacy of radiotherapy, the signals activated in resistant tumors are still unclear. This study shows that ERp57 contributes to radioresistance of laryngeal cancer by activating STAT3. Increased ERp57 was associated with the radioresistant phenotype of laryngeal cancer cells. Interestingly, increased interaction between ERp57 and STAT3 was observed in radioresistant cells, compared to the control cells. This physical complex is required for the activation of STAT3 in the radioresistant cells. Among STAT3-regulatory genes, Mcl-1 was predominantly regulated by ERp57. Inhibition of STAT3 activity with a chemical inhibitor or siRNA-mediated depletion of Mcl-1 sensitized radioresistant cells to irradiation, suggesting that the ERp57-STAT3-Mcl-1 axis regulates radioresistance of laryngeal cancer cells. Furthermore, we observed a positive correlation between ERp57 and phosphorylated STAT3 or Mcl-1 and in vivo interactions between ERp57 and STAT3 in human laryngeal cancer. Importantly, we also found that increased ERp57-STAT3 complex was associated with poor prognosis in human laryngeal cancer, indicating the prognostic role of ERp57-STAT3 regulation. Overall, our data suggest that ERp57-STAT3 regulation functions in radioresistance of laryngeal cancer, and targeting the ERp57-STAT3 pathway might be important for enhancing the efficacy of radiotherapy in human laryngeal cancer.

  20. Prevention of Trauma and Hemorrhagic Shock-Mediated Liver Apoptosis by Activation of Stat3α

    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 Stat3β, a naturally occurring, dominant-negative isoform of the Stat3, attenuated trauma/HS-induced liver apoptosis, confirming a role for Stat3, especially Stat3α, 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 Stat3α, which normalizes the trauma/HS-induced liver apoptosis transcriptome. PMID:18997875

  1. An Activating Mutation in STAT3 Results in Neonatal Diabetes Through Reduced Insulin Synthesis.

    PubMed

    Velayos, Teresa; Martínez, Rosa; Alonso, Milagros; Garcia-Etxebarria, Koldo; Aguayo, Anibal; Camarero, Cristina; Urrutia, Inés; Martínez de LaPiscina, Idoia; Barrio, Raquel; Santin, Izortze; Castaño, Luis

    2017-04-01

    Neonatal diabetes mellitus (NDM) is a rare form of diabetes diagnosed within the first 6 months of life. Genetic studies have allowed the identification of several genes linked to the development of NDM; however, genetic causes for ∼20% of the cases remain to be clarified. Most cases of NDM involve isolated diabetes, but sometimes NDM appears in association with other pathological conditions, including autoimmune diseases. Recent reports have linked activating mutations in STAT3 with early-onset autoimmune disorders that include diabetes of autoimmune origin, but the functional impact of STAT3-activating mutations have not been characterized at the pancreatic β-cell level. By using whole-exome sequencing, we identified a novel missense mutation in the binding domain of the STAT3 protein in a patient with NDM. The functional analyses showed that the mutation results in an aberrant activation of STAT3, leading to deleterious downstream effects in pancreatic β-cells. The identified mutation leads to hyperinhibition of the transcription factor Isl-1 and, consequently, to a decrease in insulin expression. These findings represent the first functional indication of a direct link between an NDM-linked activating mutation in STAT3 and pancreatic β-cell dysfunction.

  2. MicroRNA-424 impairs ubiquitination to activate STAT3 and promote prostate tumor progression

    PubMed Central

    Dallavalle, Cecilia; Civenni, Gianluca; Merulla, Jessica; Ostano, Paola; Mello-Grand, Maurizia; Rossi, Simona; Losa, Marco; D’Ambrosio, Gioacchino; Sessa, Fausto; Thalmann, George N.; Zitella, Andrea; Chiorino, Giovanna; Catapano, Carlo V.

    2016-01-01

    Mutations and deletions in components of ubiquitin ligase complexes that lead to alterations in protein turnover are important mechanisms in driving tumorigenesis. Here we describe an alternative mechanism involving upregulation of the microRNA miR-424 that leads to impaired ubiquitination and degradation of oncogenic transcription factors in prostate cancers. We found that miR-424 targets the E3 ubiquitin ligase COP1 and identified STAT3 as a key substrate of COP1 in promoting tumorigenic and cancer stem-like properties in prostate epithelial cells. Altered protein turnover due to impaired COP1 function led to accumulation and enhanced basal and cytokine-induced activity of STAT3. We further determined that loss of the ETS factor ESE3/EHF is the initial event that triggers the deregulation of the miR-424/COP1/STAT3 axis. COP1 silencing and STAT3 activation were effectively reverted by blocking of miR-424, suggesting a possible strategy to attack this key node of tumorigenesis in ESE3/EHF–deficient tumors. These results establish miR-424 as an oncogenic effector linked to noncanonical activation of STAT3 and as a potential therapeutic target. PMID:27820701

  3. Stat3 Activation in Urothelial Stem Cells Leads to Direct Progression to Invasive Bladder Cancer

    PubMed Central

    Ho, Philip Levy; Lay, Erica Julianne; Jian, Weiguo; Parra, Diana; Chan, Keith Syson

    2012-01-01

    Two subtypes of human bladder cancer, noninvasive papillary and muscle-invasive cancer, develop through independent pathologic and molecular pathways. Human invasive bladder cancer frequently develops without prior clinical evidence of a noninvasive tumor stage. However, an animal model that recapitulates this unique clinical progression of invasive bladder cancer has not yet been developed. In this study, we created a novel transgenic mouse model of invasive bladder cancer by targeting an active dimerized form of Stat3 to the basal cells of bladder epithelium. When exposed to the carcinogen nitrosamine, Stat3-transgenic mice developed invasive cancer directly from carcinoma in situ (CIS), bypassing the noninvasive papillary tumor stage. Remarkably, invasive bladder cancer driven by active Stat3 was predominantly composed of stem cells, which were characterized by cytokeratin 14 (CK14) staining and enhanced tumor sphere-forming ability. Active Stat3 was also shown to localize to the nucleus of human invasive bladder cancers that were primarily composed of CK14+ stem cells. Together, our findings show that Stat3-induced stem cell expansion plays a critical role in the unique clinical progression of invasive bladder cancer through the CIS pathway. PMID:22532166

  4. Signal transducer and activator of transcription 3 (STAT3) homologue in turbot (Scophthalmus maximus): molecular characterization and expression analysis.

    PubMed

    Wang, Na; Yang, Chang-Geng; Sun, Zhong-Zhi; Wang, Xian-Li; Chen, Song-Lin

    2011-01-01

    Signal transducer and activator of transcription 3 (STAT3) acts as an important mediator in multiple biological processes induced by different cytokines. So far, little information is available in fish STAT3. In this study, turbot (Scophthalmus maximus) STAT3 gene was cloned and characterized for the first time. The turbot STAT3 full-length cDNA consists of 2355 nucleotides encoding a polypeptide of 784 amino acids with four conserved domains including STAT_int, STAT_alpha, STAT_bind and SH2 domain. The phylogenetic tree showed that turbot STAT3 shared the closest relationship with mandarin fish (Siniperca chuatsi) STAT3. The autoactivation experiment in yeast proved that turbot STAT3 was a strong transcription factor. The quantitative RT-PCR experiment indicated that Stat3 mRNA was expressed in widespread tissues with the highest expression levels in the liver. And the further expression patterns analysis revealed that turbot Stat3 expression levels were increased in liver, spleen, kidney of fish infected with Vibrio anguillarum and liver of fish infected with LCDV. Meantime, hepcidin, one of STAT3 target gene, was also up-regulated in liver of fish infected with two pathogens. These results suggested that turbot Stat3 may involved in the immune defense process as a transcription factor.

  5. Acetylation directs survivin nuclear localization to repress STAT3 oncogenic activity.

    PubMed

    Wang, Haijuan; Holloway, Michael P; Ma, Li; Cooper, Zachary A; Riolo, Matthew; Samkari, Ayman; Elenitoba-Johnson, Kojo S J; Chin, Y Eugene; Altura, Rachel A

    2010-11-12

    The multiple functions of the oncofetal protein survivin are dependent on its selective expression patterns within immunochemically distinct subcellular pools. The mechanism by which survivin localizes to these compartments, however, is only partly understood. Here we show that nuclear accumulation of survivin is promoted by CREB-binding protein (CBP)-dependent acetylation on lysine 129 (129K, Lys-129). We demonstrate a mechanism by which survivin acetylation at this position results in its homodimerization, while deacetylation promotes the formation of survivin monomers that heterodimerize with CRM1 and facilitate its nuclear export. Using proteomic analysis, we identified the oncogenic transcription factor STAT3 as a binding partner of nuclear survivin. We show that acetylated survivin binds to the N-terminal transcriptional activation domain of the STAT3 dimer and represses STAT3 transactivation of target gene promoters. Using multiplex PCR and DNA sequencing, we identified a single-nucleotide polymorphism (A → G) at Lys-129 that exists as a homozygous mutation in a neuroblastoma cell line and corresponds with a defect in survivin nuclear localization. Our results demonstrate that the dynamic equilibrium between survivin acetylation and deacetylation at amino acid 129 determines its interaction with CRM1, its subsequent subcellular localization, and its ability to inhibit STAT3 transactivation, providing a potential route for therapeutic intervention in STAT3-dependent tumors.

  6. AG490 inhibits NFATc1 expression and STAT3 activation during RANKL induced osteoclastogenesis

    SciTech Connect

    Li, Chang-hong; Zhao, Jin-xia; Sun, Lin; Yao, Zhong-qiang; Deng, Xiao-li; Liu, Rui; Liu, Xiang-yuan

    2013-06-14

    Highlights: •AG490 inhibits RANKL-induced osteoclastogenesis in RAW264.7 cells. •AG490 affects cell proliferation and cell cycle distribution. •AG490 reduces NFATc1 expression during RANKL-induced osteoclastogenesis. •AG490 disrupts the activation of RANKL-mediated JAK2/STAT3 signaling pathway. •STAT3 depletion partly mimics the effect of AG490 on RANKL-induced osteoclastogenesis. -- Abstract: Commonly, JAK/STAT relays cytokine signals for cell activation and proliferation, and recent studies have shown that the elevated expression of JAK/STAT is associated with the immune rejection of allografts and the inflammatory processes of autoimmune disease. However, the role which JAK2/STAT3 signaling plays in the receptor activator of nuclear factor-κB ligand (RANKL)-mediated osteoclastogenesis is unknown. In this study, we investigated the effects of AG490, specific JAK2 inhibitor, on osteoclast differentiation in vitro. AG490 significantly inhibited osteoclastogenesis in murine osteoclast precursor cell line RAW264.7 induced by RANKL. AG490 suppressed cell proliferation and delayed the G1 to S cell cycle transition. Furthermore, AG490 also suppressed the expression of nuclear factor of activated T cells (NFAT) c1 but not c-Fos in RAW264.7. Subsequently, we investigated various intracellular signaling components associated with osteoclastogenesis. AG490 had no effects on RANKL-induced activation of Akt, ERK1/2. Interestingly, AG490 partly inhibited RANKL-induced phosphorylation of Ser{sup 727} in STAT3. Additionally, down-regulation of STAT3 using siRNA resulted in suppression of TRAP, RANK and NFATc1 expression. In conclusion, we demonstrated that AG490 inhibited RANKL-induced osteoclastogenesis by suppressing NFATc1 production and cell proliferation via the STAT3 pathway. These results suggest that inhibition of JAK2 may be useful for the treatment of bone diseases characterized by excessive osteoclastogenesis.

  7. Signal transducer and activator of transcription 3 (Stat3) expression and activation in rat uterus during early pregnancy.

    PubMed

    Teng, Chun-Bo; Diao, Hong-Lu; Ma, Hong; Cong, Jing; Yu, Hao; Ma, Xing-Hong; Xu, Li-Bin; Yang, Zeng-Ming

    2004-08-01

    Signal transducer and activator of transcription 3 (Stat3), a member of the Stat family, is specifically activated during mouse embryo implantation. The aim of this study was to investigate the expression, activation and regulation of Stat3 in rat uterus during early pregnancy, pseudopregnancy, delayed implantation and artificial decidualization. Stat3 mRNA was highly expressed in the luminal epithelium on day 5 and in the luminal epithelium and underlying stromal cells at implantation sites on day 6 of pregnancy. There was a strong level of Stat3 protein expression and phosphorylation in the stromal cells near the lumen and in the luminal epithelium on day 5 of pregnancy, which was similar to day 5 of pseudopregnancy. In the afternoon of day 6, the strong level of Stat3 phosphorylation was detected only in the luminal epithelium. Stat3 was highly expressed and activated in the decidual cells from days 7 to 9 of pregnancy and under artificial decidualization in the present study. Our results suggest that the strong level of Stat3 activation in the luminal epithelium and underlying stromal cells during the pre-implantation period may be important for establishing uterine receptivity as in mice, and the high level of Stat3 expression and activation in decidual cells may play a role during decidualization.

  8. Sphingosine-1-phosphate lyase downregulation promotes colon carcinogenesis through STAT3-activated microRNAs.

    PubMed

    Degagné, Emilie; Pandurangan, Ashok; Bandhuvula, Padmavathi; Kumar, Ashok; Eltanawy, Abeer; Zhang, Meng; Yoshinaga, Yuko; Nefedov, Mikhail; de Jong, Pieter J; Fong, Loren G; Young, Stephen G; Bittman, Robert; Ahmedi, Yasmin; Saba, Julie D

    2014-12-01

    Growing evidence supports a link between inflammation and cancer; however, mediators of the transition between inflammation and carcinogenesis remain incompletely understood. Sphingosine-1-phosphate (S1P) lyase (SPL) irreversibly degrades the bioactive sphingolipid S1P and is highly expressed in enterocytes but downregulated in colon cancer. Here, we investigated the role of SPL in colitis-associated cancer (CAC). We generated mice with intestinal epithelium-specific Sgpl1 deletion and chemically induced colitis and tumor formation in these animals. Compared with control animals, mice lacking intestinal SPL exhibited greater disease activity, colon shortening, cytokine levels, S1P accumulation, tumors, STAT3 activation, STAT3-activated microRNAs (miRNAs), and suppression of miR-targeted anti-oncogene products. This phenotype was attenuated by STAT3 inhibition. In fibroblasts, silencing SPL promoted tumorigenic transformation through a pathway involving extracellular transport of S1P through S1P transporter spinster homolog 2 (SPNS2), S1P receptor activation, JAK2/STAT3-dependent miR-181b-1 induction, and silencing of miR-181b-1 target cylindromatosis (CYLD). Colon biopsies from patients with inflammatory bowel disease revealed enhanced S1P and STAT3 signaling. In mice with chemical-induced CAC, oral administration of plant-type sphingolipids called sphingadienes increased colonic SPL levels and reduced S1P levels, STAT3 signaling, cytokine levels, and tumorigenesis, indicating that SPL prevents transformation and carcinogenesis. Together, our results suggest that dietary sphingolipids can augment or prevent colon cancer, depending upon whether they are metabolized to S1P or promote S1P metabolism through the actions of SPL.

  9. Sphingosine-1-phosphate lyase downregulation promotes colon carcinogenesis through STAT3-activated microRNAs

    PubMed Central

    Degagné, Emilie; Pandurangan, Ashok; Bandhuvula, Padmavathi; Kumar, Ashok; Eltanawy, Abeer; Zhang, Meng; Yoshinaga, Yuko; Nefedov, Mikhail; de Jong, Pieter J.; Fong, Loren G.; Young, Stephen G.; Bittman, Robert; Ahmedi, Yasmin; Saba, Julie D.

    2014-01-01

    Growing evidence supports a link between inflammation and cancer; however, mediators of the transition between inflammation and carcinogenesis remain incompletely understood. Sphingosine-1-phosphate (S1P) lyase (SPL) irreversibly degrades the bioactive sphingolipid S1P and is highly expressed in enterocytes but downregulated in colon cancer. Here, we investigated the role of SPL in colitis-associated cancer (CAC). We generated mice with intestinal epithelium-specific Sgpl1 deletion and chemically induced colitis and tumor formation in these animals. Compared with control animals, mice lacking intestinal SPL exhibited greater disease activity, colon shortening, cytokine levels, S1P accumulation, tumors, STAT3 activation, STAT3-activated microRNAs (miRNAs), and suppression of miR-targeted anti-oncogene products. This phenotype was attenuated by STAT3 inhibition. In fibroblasts, silencing SPL promoted tumorigenic transformation through a pathway involving extracellular transport of S1P through S1P transporter spinster homolog 2 (SPNS2), S1P receptor activation, JAK2/STAT3-dependent miR-181b-1 induction, and silencing of miR-181b-1 target cylindromatosis (CYLD). Colon biopsies from patients with inflammatory bowel disease revealed enhanced S1P and STAT3 signaling. In mice with chemical-induced CAC, oral administration of plant-type sphingolipids called sphingadienes increased colonic SPL levels and reduced S1P levels, STAT3 signaling, cytokine levels, and tumorigenesis, indicating that SPL prevents transformation and carcinogenesis. Together, our results suggest that dietary sphingolipids can augment or prevent colon cancer, depending upon whether they are metabolized to S1P or promote S1P metabolism through the actions of SPL. PMID:25347472

  10. Evaluation of quantitative assays for the identification of direct signal transducer and activator of transcription 3 (STAT3) inhibitors.

    PubMed

    Furtek, Steffanie L; Matheson, Christopher J; Backos, Donald S; Reigan, Philip

    2016-11-22

    In many forms of cancer the signal transducer and activator of transcription 3 (STAT3) transcription factor remains constitutively active, driving cancer survival and progression. The critical role of STAT3 in tumorigenesis has prompted a campaign of drug discovery programs to identify small molecules that disrupt the function of STAT3, with more recent efforts focusing on direct STAT3 inhibition. There are two target binding sites for direct STAT3 inhibitors: the SH2 dimerization domain and the DNA-binding domain. An in vitro fluorescence polarization assay, using recombinant STAT3 protein, has successfully identified compounds that target the SH2 domain; however, no assay has been reported to identify inhibitors that bind the DNA-binding domain. The lack of such a quantitative assay has limited the identification and development of STAT3 DNA-binding domain inhibitors. Here, we report a modified DNA-binding ELISA to incorporate recombinant STAT3 protein to evaluate small molecules that prevent STAT3-DNA binding. The concomitant use of the ELISA and fluorescence polarization assay enables the classification of direct STAT3 inhibitors by their site of action. Our data provide further support that niclosamide inhibits STAT3 through interaction with the DNA-binding domain. Furthermore, the ELISA can support medicinal chemistry efforts by identifying DNA-binding domain inhibitors and allowing the determination of an IC50 value, supporting the ranking of inhibitors and development of structure-activity relationships. Therefore, we propose a tandem evaluation approach to identify small molecules that target the SH2 domain or the DNA-binding domain of STAT3, which allows for quantitative evaluation of candidate STAT3 inhibitors.

  11. Evaluation of quantitative assays for the identification of direct signal transducer and activator of transcription 3 (STAT3) inhibitors

    PubMed Central

    Furtek, Steffanie L.; Matheson, Christopher J.; Backos, Donald S.; Reigan, Philip

    2016-01-01

    In many forms of cancer the signal transducer and activator of transcription 3 (STAT3) transcription factor remains constitutively active, driving cancer survival and progression. The critical role of STAT3 in tumorigenesis has prompted a campaign of drug discovery programs to identify small molecules that disrupt the function of STAT3, with more recent efforts focusing on direct STAT3 inhibition. There are two target binding sites for direct STAT3 inhibitors: the SH2 dimerization domain and the DNA-binding domain. An in vitro fluorescence polarization assay, using recombinant STAT3 protein, has successfully identified compounds that target the SH2 domain; however, no assay has been reported to identify inhibitors that bind the DNA-binding domain. The lack of such a quantitative assay has limited the identification and development of STAT3 DNA-binding domain inhibitors. Here, we report a modified DNA-binding ELISA to incorporate recombinant STAT3 protein to evaluate small molecules that prevent STAT3-DNA binding. The concomitant use of the ELISA and fluorescence polarization assay enables the classification of direct STAT3 inhibitors by their site of action. Our data provide further support that niclosamide inhibits STAT3 through interaction with the DNA-binding domain. Furthermore, the ELISA can support medicinal chemistry efforts by identifying DNA-binding domain inhibitors and allowing the determination of an IC50 value, supporting the ranking of inhibitors and development of structure-activity relationships. Therefore, we propose a tandem evaluation approach to identify small molecules that target the SH2 domain or the DNA-binding domain of STAT3, which allows for quantitative evaluation of candidate STAT3 inhibitors. PMID:27793003

  12. Hippocalcin Is Required for Astrocytic Differentiation through Activation of Stat3 in Hippocampal Neural Precursor Cells

    PubMed Central

    Kang, Min-Jeong; Park, Shin-Young; Han, Joong-Soo

    2016-01-01

    Hippocalcin (Hpca) is a neuronal calcium sensor protein expressed in the mammalian brain. However, its function in neural stem/precursor cells has not yet been studied. Here, we clarify the function of Hpca in astrocytic differentiation in hippocampal neural precursor cells (HNPCs). When we overexpressed Hpca in HNPCs in the presence or absence of bFGF, expression levels of nerve-growth factors such as neurotrophin-3 (NT-3), neurotrophin-4/5 (NT-4/5), and brain-derived neurotrophic factor (BDNF), together with the proneural basic helix loop helix (bHLH) transcription factors NeuroD and neurogenin 1 (Ngn1), increased significantly. In addition, there was an increase in the number of cells expressing glial fibrillary acidic protein (GFAP), an astrocyte marker, and in branch outgrowth, indicating astrocytic differentiation of the HNPCs. Downregulation of Hpca by transfection with Hpca siRNA reduced expression of NT-3, NT-4/5, BDNF, NeuroD, and Ngn1 as well as levels of GFAP protein. Furthermore, overexpression of Hpca increased the phosphorylation of STAT3 (Ser727), and this effect was abolished by treatment with a STAT3 inhibitor (S3I-201), suggesting that STAT3 (Ser727) activation is involved in Hpca-mediated astrocytic differentiation. As expected, treatment with Stat3 siRNA or STAT3 inhibitor caused a complete inhibition of astrogliogenesis induced by Hpca overexpression. Taken together, this is the first report to show that Hpca, acting through Stat3, has an important role in the expression of neurotrophins and proneural bHLH transcription factors, and that it is an essential regulator of astrocytic differentiation and branch outgrowth in HNPCs. PMID:27840601

  13. An inhibitor of cholesterol absorption displays anti-myeloma activity by targeting the JAK2-STAT3 signaling pathway

    PubMed Central

    Zhu, Jingyu; Mao, Hongwu; Lin, Xu; Zhang, Zubin; Cao, Biyin; Zeng, Yuanying; Mao, Xinliang

    2016-01-01

    The activated JAK2-STAT3 signaling pathway is a high risk factor for multiple myeloma (MM), a fatal malignancy of plasma cells. In the present study, SC09, a potential inhibitor of cholesterol absorption, was identified in a STAT3-targeted drug screen. SC09 suppressed the activation of STAT3 in a time-course and concentration-dependent manner but did not affect its family members STAT1 and STAT5. SC09 inhibited STAT3 transcriptional activity and downregulated the expression of STAT3-regulated genes. Further studies showed that SC09 selectively inhibited JAK2 activation but not other kinases including c-Src, ERK, p38 and mTOR that are all associated with STAT3 activation. Moreover, SC09 obviously induced MM cell death in vitro and delayed MM tumor growth in vivo. SC09-induced MM cell death was dependent on the endogenous STAT3 status, and this effect could be attenuated by enforced expression of STAT3. All the results collectively indicated that SC09 blocks the JAK2-STAT3 signaling thus displaying anti-MM activity. Given its well tolerance and anti-MM potency, SC09 is credited for further investigation as a promising drug for MM treatment. PMID:27705908

  14. STAT3 activation and infiltration of eosinophil granulocytes in mycosis fungoides.

    PubMed

    Fredholm, Simon; Gjerdrum, Lise Mette R; Willerslev-Olsen, Andreas; Petersen, David L; Nielsen, Inger Ø; Kauczok, Claudia-S; Wobser, Marion; Ralfkiaer, Ulrik; Bonefeld, Charlotte M; Wasik, Mariusz A; Krejsgaard, Thorbjørn; Geisler, Carsten; Ralfkiaer, Elisabeth; Gniadecki, Robert; Woetmann, Anders; Odum, Niels

    2014-10-01

    Eosinophil granulocytes have been implicated in anticancer immunity but recent data indicate that eosinophils can also promote cancer. Herein, we studied eosinophils in skin lesions from 43 patients with mycosis fungoides (MF). The presence of eosinophils correlated with disease stage: 78% of patients with advanced disease displayed eosinophil infiltration, whereas this was only seen in 11% of patients with patches (p<0.01), and in 48% of those with plaque disease. Importantly, 72% of patients with positive staining for phospho-signal-transducer-and-activator-of-transcription (pY-STAT3) in malignant T-cells also stained positively for eosinophils, whereas this was only observed in 28% of pY-STAT3-negative patients (p<0.01). Notably, malignant T-cells expressed eosinophilic activation and trafficking factors: High-mobility group BOX-1 protein (HMGB1) and interleukin 5 (IL5). STAT3 siRNA profoundly inhibited IL5 but not HMGB1 expression. In conclusion, these data suggest that malignant T-cells orchestrate accumulation and activation of eosinophils supporting the notion of STAT3 being a putative target for therapy.

  15. 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 α (FRα). The function of FRα 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 FRα 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 FRα-positive HeLa cells, but not in FRα-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 FRα-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 FRα adds complexity to the established roles of B9 vitamins in cancer and neural tube defects.

  16. 14-3-3ζ Interacts with Stat3 and Regulates Its Constitutive Activation in Multiple Myeloma Cells

    PubMed Central

    Li, Wenliang; Xiong, Qian; Yang, Mingkun; Zheng, Peng; Li, Chongyang; Pei, Jianfeng; Ge, Feng

    2012-01-01

    The 14-3-3 proteins are a family of regulatory signaling molecules that interact with other proteins in a phosphorylation-dependent manner and function as adapter or scaffold proteins in signal transduction pathways. One family member, 14-3-3ζ, is believed to function in cell signaling, cycle control, and apoptotic death. A systematic proteomic analysis done in our laboratory has identified signal transducers and activators of transcription 3 (Stat3) as a novel 14-3-3ζ interacting protein. Following our initial finding, in this study, we provide evidence that 14-3-3ζ interacts physically with Stat3. We further demonstrate that phosphorylation of Stat3 at Ser727 is vital for 14-3-3ζ interaction and mutation of Ser727 to Alanine abolished 14-3-3ζ/Stat3 association. Inhibition of 14-3-3ζ protein expression in U266 cells inhibited Stat3 Ser727 phosphorylation and nuclear translocation, and decreased both Stat3 DNA binding and transcriptional activity. Moreover, 14-3-3ζ is involved in the regulation of protein kinase C (PKC) activity and 14-3-3ζ binding to Stat3 protects Ser727 dephosphorylation from protein phosphatase 2A (PP2A). Taken together, our findings support the model that multiple signaling events impinge on Stat3 and that 14-3-3ζ serves as an essential coordinator for different pathways to regulate Stat3 activation and function in MM cells. PMID:22279540

  17. Enhanced Transcriptional Activity and Mitochondrial Localization of STAT3 Co-induce Axon Regrowth in the Adult Central Nervous System.

    PubMed

    Luo, Xueting; Ribeiro, Marcio; Bray, Eric R; Lee, Do-Hun; Yungher, Benjamin J; Mehta, Saloni T; Thakor, Kinjal A; Diaz, Francisca; Lee, Jae K; Moraes, Carlos T; Bixby, John L; Lemmon, Vance P; Park, Kevin K

    2016-04-12

    Signal transducer and activator of transcription 3 (STAT3) is a transcription factor central to axon regrowth with an enigmatic ability to act in different subcellular regions independently of its transcriptional roles. However, its roles in mature CNS neurons remain unclear. Here, we show that along with nuclear translocation, STAT3 translocates to mitochondria in mature CNS neurons upon cytokine stimulation. Loss- and gain-of-function studies using knockout mice and viral expression of various STAT3 mutants demonstrate that STAT3's transcriptional function is indispensable for CNS axon regrowth, whereas mitochondrial STAT3 enhances bioenergetics and further potentiates regrowth. STAT3's localization, functions, and growth-promoting effects are regulated by mitogen-activated protein kinase kinase (MEK), an effect further enhanced by Pten deletion, leading to extensive axon regrowth in the mouse optic pathway and spinal cord. These results highlight CNS neuronal dependence on STAT3 transcriptional activity, with mitochondrial STAT3 providing ancillary roles, and illustrate a critical contribution for MEK in enhancing diverse STAT3 functions and axon regrowth.

  18. Photodynamic therapy activated signaling from epidermal growth factor receptor and STAT3

    PubMed Central

    Edmonds, Christine; Hagan, Sarah; Gallagher-Colombo, Shannon M.; Busch, Theresa M.; Cengel, Keith A.

    2012-01-01

    Patients with serosal (pleural or peritoneal) spread of malignancy have few definitive treatment options and consequently have a very poor prognosis. We have previously shown that photodynamic therapy (PDT) can be an effective treatment for these patients, but that the therapeutic index is relatively narrow. Here, we test the hypothesis that EGFR and STAT3 activation increase survival following PDT, and that inhibiting these pathways leads to increased PDT-mediated direct cellular cytotoxicity by examining BPD-PDT in OvCa and NSCLC cells. We found that BPD-mediated PDT stimulated EGFR tyrosine phosphorylation and nuclear translocation, and that EGFR inhibition by erlotinib resulted in reduction of PDT-mediated EGFR activation and nuclear translocation. Nuclear translocation and PDT-mediated activation of EGFR were also observed in response to BPD-mediated PDT in multiple cell lines, including OvCa, NSCLC and head and neck cancer cells, and was observed to occur in response to porfimer sodium-mediated PDT. In addition, we found that PDT stimulates nuclear translocation of STAT3 and STAT3/EGFR association and that inhibiting STAT3 signaling prior to PDT leads to increased PDT cytotoxicity. Finally, we found that inhibition of EGFR signaling leads to increased PDT cytotoxicity through a mechanism that involves increased apoptotic cell death. Taken together, these results demonstrate that PDT stimulates the nuclear accumulation of both EGFR and STAT3 and that targeting these survival pathways is a potentially promising strategy that could be adapted for clinical trials of PDT for patients with serosal spread of malignancy. PMID:22986230

  19. Involvement of fish signal transducer and activator of transcription 3 (STAT3) in SGIV replication and virus induced paraptosis.

    PubMed

    Huang, Xiaohong; Huang, Youhua; Yang, Ying; Wei, Shina; Qin, Qiwei

    2014-12-01

    Signal transducer and activator of transcription 3 (STAT3) is an important transcription factor which plays crucial roles in immune regulation, inflammation, cell proliferation, transformation, and other physiological processes of the organism. In this study, a novel STAT3 gene from orange spotted grouper (Ec-STAT3) was cloned and characterized. Bioinformatic analysis revealed that full-length of Ec-STAT3 was 3105-bp long and contained a 280-bp 5'UTR, a 470-bp 3'UTR, and a 2355-bp open reading frame (ORF) that encoded a 784-amino acid peptide. The deduced protein of Ec-STAT3 showed 98% identity to that of turbot (Scophthalmus maximus). Amino acid alignment showed that Ec-STAT3 contained four conserved domains, including a protein interaction domain, a coiled coil domain, a DNA binding domain, and an SH2 domain. Quantitative real-time PCR analysis showed that the highest expression level was detected in the liver, followed by skin and spleen. After injection with Singapore grouper iridovirus (SGIV), the transcript of Ec-STAT3 in spleen was increased significantly. To further explore the function of Ec-STAT3, we investigated the roles of Ec-STAT3 in SGIV infection in vitro. Immune fluorescence analysis indicated that SGIV infection altered the distribution of phosphorylated Ec-STAT3 in nucleus, and a small part of phosphorylated Ec-STAT3 was associated with virus assembly sites, suggesting that Ec-STAT3 might be important for SGIV infection. Using STAT3 specific inhibitor, S3I-201, we found that inhibition of Ec-STAT3 activation decreased the SGIV replication significantly. Moreover, inhibition of Ec-STAT3 activation obviously altered SGIV infection induced cell cycle arrest and the expression of pro-survival genes, including Bcl-2, Bcl-xL and Bax inhibitor. Together, our results firstly demonstrated the critical roles of fish STAT3 in DNA virus replication and virus induced paraptosis, but also provided new insights into the mechanism of iridovirus pathogenesis.

  20. Enhanced Stat3 activation in POMC neurons provokes negative feedback inhibition of leptin and insulin signaling in obesity.

    PubMed

    Ernst, Marianne B; Wunderlich, Claudia M; Hess, Simon; Paehler, Moritz; Mesaros, Andrea; Koralov, Sergei B; Kleinridders, André; Husch, Andreas; Münzberg, Heike; Hampel, Brigitte; Alber, Jens; Kloppenburg, Peter; Brüning, Jens C; Wunderlich, F Thomas

    2009-09-16

    Leptin-stimulated Stat3 activation in proopiomelanocortin (POMC)-expressing neurons of the hypothalamus plays an important role in maintenance of energy homeostasis. While Stat3 activation in POMC neurons is required for POMC expression, the role of elevated basal Stat3 activation as present in the development of obesity has not been directly addressed. Here, we have generated and characterized mice expressing a constitutively active version of Stat3 (Stat3-C) in POMC neurons (Stat3-C(POMC) mice). On normal chow diet, these animals develop obesity as a result of hyperphagia and decreased POMC expression accompanied by central leptin and insulin resistance. This unexpected finding coincides with POMC-cell-specific, Stat3-mediated upregulation of SOCS3 expression inhibiting both leptin and insulin signaling as insulin-stimulated PIP(3) (phosphatidylinositol-3,4,5 triphosphate) formation and protein kinase B (AKT) activation in POMC neurons as well as with the fact that insulin's ability to hyperpolarize POMC neurons is largely reduced in POMC cells of Stat3-C(POMC) mice. These data indicate that constitutive Stat3 activation is not sufficient to promote POMC expression but requires simultaneous PI3K (phosphoinositide 3-kinase)-dependent release of FOXO1 repression. In contrast, upon exposure to a high-fat diet, food intake and body weight were unaltered in Stat3-C(POMC) mice compared with control mice. Taken together, these experiments directly demonstrate that enhanced basal Stat3 activation in POMC neurons as present in control mice upon high-fat feeding contributes to the development of hypothalamic leptin and insulin resistance.

  1. IL-6/STAT3 signaling pathway is activated in plasma cell mastitis.

    PubMed

    Liu, Yang; Zhang, Jian; Zhou, Yu-Hui; Jiang, Yi-Na; Zhang, Wei; Tang, Xiao-Jiang; Ren, Yu; Han, Shui-Ping; Liu, Pei-Jun; Xu, Jing; He, Jian-Jun

    2015-01-01

    Plasma cell mastitis (PCM), a particular type of mastitis, mainly occurs in females at nonpregnant and nonlactating stages. The infiltration of abundant plasma cells and lymphocytes is the hallmark of the disease. The incidence rate of PCM increased gradually and its pathogenesis remained unclear. In this study, we investigated the expression of IL-6/STAT3 signaling pathway, which is vital not only for the differentiation of plasma cells but also for survival of plasma cells and T lymphocytes, in 30 PCM cases, 10 acute mastitis cases and 10 normal breast tissues by immunohistochemical analysis. IL-6 level was significantly higher in PCM patients than in acute mastitis patients or normal group. The positive rate of IL-6 and p-STAT3 staining in PCM samples was 93.3% (28/30) and 70% (21/30), respectively, and there was a significant positive association between IL-6 and p-STAT3 staining (r=0.408, P=0.025). In PCM group, the rate of nipple retraction was 40% (12/30). Significantly higher IL-6 expression was found in PCM patients with nipple retraction than in other PCM patients. However, no significant difference in IL-6 or p-STAT3 staining was detected between PCM patients experiencing recurrence and other PCM patients. In addition, Bcl-2 level was higher in PCM patients than in acute mastitis patients or normal group, but there was no difference in Bcl-2 immunostaining between PCM patients experiencing recurrence and other PCM patients. These indicate that IL-6/STAT3 signaling is activated in PCM and may play an important role in the pathogenesis of PCM.

  2. STAT3 pathway regulates lung-derived brain metastasis initiating cell capacity through miR-21 activation.

    PubMed

    Singh, Mohini; Garg, Neha; Venugopal, Chitra; Hallett, Robin; Tokar, Tomas; McFarlane, Nicole; Mahendram, Sujeivan; Bakhshinyan, David; Manoranjan, Branavan; Vora, Parvez; Qazi, Maleeha; Arpin, Carolynn C; Page, Brent; Haftchenary, Sina; Rosa, David A; Lai, Ping-Shan; Gómez-Biagi, Rodolfo F; Ali, Ahmed M; Lewis, Andrew; Geletu, Mulu; Murty, Naresh K; Hassell, John A; Jurisica, Igor; Gunning, Patrick T; Singh, Sheila K

    2015-09-29

    Brain metastases (BM) represent the most common tumor to affect the adult central nervous system. Despite the increasing incidence of BM, likely due to consistently improving treatment of primary cancers, BM remain severely understudied. In this study, we utilized patient-derived stem cell lines from lung-to-brain metastases to examine the regulatory role of STAT3 in brain metastasis initiating cells (BMICs). Annotation of our previously described BMIC regulatory genes with protein-protein interaction network mapping identified STAT3 as a novel protein interactor. STAT3 knockdown showed a reduction in BMIC self-renewal and migration, and decreased tumor size in vivo. Screening of BMIC lines with a library of STAT3 inhibitors identified one inhibitor to significantly reduce tumor formation. Meta-analysis identified the oncomir microRNA-21 (miR-21) as a target of STAT3 activity. Inhibition of miR-21 displayed similar reductions in BMIC self-renewal and migration as STAT3 knockdown. Knockdown of STAT3 also reduced expression of known downstream targets of miR-21. Our studies have thus identified STAT3 and miR-21 as cooperative regulators of stemness, migration and tumor initiation in lung-derived BM. Therefore, STAT3 represents a potential therapeutic target in the treatment of lung-to-brain metastases.

  3. The Antiproliferative and Colony-suppressive Activities of STAT3 Inhibitors in Human Cancer Cells Is Compromised Under Hypoxic Conditions.

    PubMed

    Tian, Jilai; Xiao, Hui; Wu, Ruohan; Cao, Yang; Li, Chenglong; Xu, Ronald; Pierson, Christopher R; Finlay, Jonathan L; Yang, Fang; Gu, Ning; Lin, Jiayuh

    2017-02-01

    Constitutive activation of signal transducer and activator of transcription 3 (STAT3) has been indicated as a novel cancer drug target, since it plays an important role in diverse oncogenic processes including survival, cell proliferation and migration. Emerging STAT3 inhibitors have demonstrated efficacy in cancer cells and animal tumor models. It is well known that most solid tumors are characterized by hypoxia, but it is not clear if hypoxic conditions affect activity of STAT3 inhibitors. To examine this, two STAT3 inhibitors were tested to investigate their inhibitory efficacy in cancer cells grown under hypoxic conditions compared with those without hypoxia. Cell proliferation, colony formation and western blot assays were performed to examine the differences in the cell viability, proliferation and proteins in the STAT3 pathway. Under hypoxic conditions, the half-maximal inhibitory concentration values for both STAT3 inhibitors were increased compared to normoxic conditions in human pancreatic cancer, medulloblastoma and sarcoma cell lines. In addition, the ability of both STAT3 inhibitors to inhibit colony formation in pancreatic cancer, medulloblastoma and sarcoma cell lines was reduced under hypoxic conditions when compared to cells under normoxic conditions. Furthermore, there was an increase in phosphorylated STAT3 levels in cancer cells under hypoxic conditions, suggesting this may be one of the mechanisms of resistance. In summary, the results presented here provide a novel finding of STAT3 inhibitor activity under hypoxic conditions and indicate that under such low oxygen conditions, the anticancer efficacy of STAT3 inhibitors was indeed hampered. These results highlight the need to develop new therapeutic strategies to overcome the resistance of cancer cells to STAT3 inhibitors under hypoxic conditions.

  4. STAT3 activation in response to IL-6 is prolonged by the binding of IL-6 receptor to EGF receptor

    PubMed Central

    Wang, Yuxin; van Boxel-Dezaire, Anette H. H.; Cheon, HyeonJoo; Yang, Jinbo; Stark, George R.

    2013-01-01

    The activation of STAT3 by tyrosine phosphorylation, essential for normal development and for a normal inflammatory response to invading pathogens, is kept in check by negative regulators. Abnormal constitutive activation of STAT3, which contributes to the pathology of cancer and to chronic inflammatory diseases such as rheumatoid arthritis, occurs when negative regulation is not fully effective. SOCS3, the major negative regulator of STAT3, is induced by tyrosine-phosphorylated STAT3 and terminates STAT3 phosphorylation about 2 h after initial exposure of cells to members of the IL-6 family of cytokines by binding cooperatively to the common receptor subunit gp130 and JAKs 1 and 2. We show here that when the epidermal growth factor receptor (EGFR) is present and active, STAT3 is rephosphorylated about 4 h after exposure of cells to IL-6 or oncostatin M and remains active for many hours. Newly synthesized IL-6 drives association of the IL-6 receptor and gp130 with EGFR, leading to EGFR-dependent rephosphorylation of STAT3, which is not inhibited by the continued presence of SOCS3. This second wave of STAT3 activation supports sustained expression of a subset of IL-6-induced proteins, several of which play important roles in inflammation and cancer, in which both IL-6 secretion and EGFR levels are often elevated. PMID:24082147

  5. Requirement of Stat3 but not Stat1 activation for epidermal growth factor receptor- mediated cell growth In vitro.

    PubMed Central

    Grandis, J R; Drenning, S D; Chakraborty, A; Zhou, M Y; Zeng, Q; Pitt, A S; Tweardy, D J

    1998-01-01

    Stimulation of epidermal growth factor receptor (EGFR) by ligand(s) leads to activation of signaling molecules including Stat1 and Stat3, two members of the signal transducers and activators of transcription (STAT) protein family. Activation of Stat1 and Stat3 was constitutive in transformed squamous epithelial cells, which produce elevated levels of TGF-alpha, and was enhanced by the addition of exogenous TGF-alpha. Targeting of Stat3 using antisense oligonucleotides directed against the translation initiation site, resulted in significant growth inhibition. In addition, cells stably transfected with dominant negative mutant Stat3 constructs failed to proliferate in vitro. In contrast, targeting of Stat1 using either antisense or dominant-negative strategies had no effect on cell growth. Thus, TGF-alpha/EGFR-mediated autocrine growth of transformed epithelial cells is dependent on activation of Stat3 but not Stat1. PMID:9769331

  6. HtrA2 suppresses autoimmune arthritis and regulates activation of STAT3

    PubMed Central

    Lee, Seung Hoon; Moon, Young-Mee; Seo, Hyeon-Beom; Kim, Se-Young; Kim, Eun-Kyung; Yi, Junyeong; Nam, Min-Kyung; Min, Jun-Ki; Park, Sung-Hwan; Rhim, Hyangshuk; Cho, Mi-La

    2016-01-01

    Rheumatoid arthritis (RA) is an autoimmune disease that is related to the induction of T helper (Th)17 cells, which secrete interleukin-17, and activation of the signal transducer and activator of transcription (STAT) 3. The expression of high-temperature requirement protein A (HtrA) 2, a serine protease involved in apoptosis, was decreased in RA patients nonresponsive to drug treatment of RA. The aim of this study was to determine whether overexpression of HtrA2 has a therapeutic effect on RA. Th17 differentiation, osteoclastogenesis, and lymphocyte activation are increased in motor neuron degeneration (mnd)2 mice, which lack HtrA2 activity because of a missense mutation (Ser276Cys) in the protease domain of HtrA2. The inhibitor of HtrA2 also increased Th17 differentiation. On the other hand, HtrA2 induced cleavage of STAT3 and overexpression of HtrA2 attenuated CIA in a mouse model. HtrA2 overexpression inhibited plaque development as well as the differentiation of Th17 in ApoE−/− mice after immunization with proteoglycans to induce a hyperlipidemia-based RA animal model. The therapeutic function of HtrA2 in inflammatory diseases is linked with Th17 development and the STAT3 pathway in splenocytes. These results suggest that HtrA2 participates in immunomodulatory activity where the upregulation of HtrA2 may shed light on therapeutic approaches to RA and hyperlipidemia. PMID:28008946

  7. T-cell growth transformation by herpesvirus saimiri is independent of STAT3 activation.

    PubMed

    Heck, Elke; Lengenfelder, Doris; Schmidt, Monika; Müller-Fleckenstein, Ingrid; Fleckenstein, Bernhard; Biesinger, Brigitte; Ensser, Armin

    2005-05-01

    Herpesvirus saimiri (saimirine herpesvirus 2) (HVS), a T-lymphotropic tumor virus, induces lymphoproliferative disease in several species of New World primates. In addition, strains of HVS subgroup C are able to transform T cells of Old World primates, including humans, to permanently growing T-cell lines. In concert with the Stp oncoprotein, the tyrosine kinase-interacting protein (Tip) of HVS C488 is required for T-cell transformation in vitro and lymphoma induction in vivo. Tip was previously shown to interact with the protein tyrosine kinase Lck. Constitutive activation of signal transducers and activators of transcription (STATs) has been associated with oncogenesis and has also been detected in HVS-transformed T-cell lines. Furthermore, Tip contains a putative consensus YXPQ binding motif for the SH2 (src homology 2) domains of STAT1 and STAT3. Tip tyrosine phosphorylation at this site was required for binding of STATs and induction of STAT-dependent transcription. Here we sought to address the relevance of STAT activation for transformation of human T cells by introducing a tyrosine-to-phenylalanine mutation in the YXPQ motif of Tip of HVS C488. Unexpectedly, the recombinant virus was still able to transform human T lymphocytes, but it had lost its capability to activate STAT3 as well as STAT1. This demonstrates that growth transformation by HVS is independent of STAT3 activation.

  8. Stat3 signaling is present and active during development of the central nervous system and eye of vertebrates.

    PubMed

    Yan, Ye; Bian, Wei; Xie, Zhiqin; Cao, Xinmin; Le Roux, Isabelle; Guillemot, Francois; Jing, Naihe

    2004-10-01

    Stat3, a member of the signal transducer and activator of transcription (STAT) family, plays a central role in mediating cell growth, differentiation, and survival signals. In this report, we show that Stat3 immunoreactivity was localized to specific regions in the developing mouse brain, neural tube, and eye from embryonic day 10.5 to postnatal day 0. The active form of Stat3 protein, which is phosphorylated on tyrosine 705 (pYStat3), was also found in the developing neural tube with more restricted distribution. An in ovo chick embryo electroporation assay showed that the endogenous chick Stat3 could drive consensus sis-inducible element-directed reporter gene expression. These results demonstrate that the active Stat3 protein is present and might play a role during the development of the central nervous system and eye.

  9. Signal Transducer and Activator of Transcription (STAT)-3 Activates Nuclear Factor (NF)-κB in Chronic Lymphocytic Leukemia Cells

    PubMed Central

    Liu, Zhiming; Hazan-Halevy, Inbal; Harris, David M.; Li, Ping; Ferrajoli, Alessandra; Faderl, Stefan; Keating, Michael J.; Estrov, Zeev

    2014-01-01

    Nuclear factor (NF)-κB plays a major role in the pathogenesis of B-cell neoplasms. A broad array of mostly extracellular stimuli has been reported to activate NF-κB, to various degrees, in chronic lymphocytic leukemia (CLL) cells. Because CLL cells harbor high levels of unphosphorylated (U) signal transducer and activator of transcription (STAT)-3 protein and U-STAT3 was reported to activate NF-κB, we sought to determine whether U-STAT3 activates NF-κB in CLL. Using the electrophoretic mobility shift assay (EMSA) we studied peripheral blood low-density cells from 15 patients with CLL and found that CLL cell nuclear extracts from all the samples bound to an NF-κB DNA probe, suggesting that NF-κB is constitutively activated in CLL. Immunoprecipitation studies showed that STAT3 bound NF-κB p65, and confocal microscopy studies detected U-STAT3/NF-κB complexes in the nuclei of CLL cells, thereby confirming these findings. Furthermore, infection of CLL cells with retroviral STAT3-shRNA attenuated the binding of NF-κB to DNA, as assessed by EMSA, and downregulated mRNA levels of NF-κB-regulated genes, as assessed by quantitative polymerase chain reaction. Taken together, our data suggest that U-STAT3 binds to the NF-κB p50/p65 dimers and that the U-STAT3/NF-κB complexes bind to DNA and activate NF-κB-regulated genes in CLL cells. PMID:21364020

  10. A novel small molecule agent displays potent anti-myeloma activity by inhibiting the JAK2-STAT3 signaling pathway

    PubMed Central

    Zhu, Jingyu; Xu, Yujia; Wang, Siyu; Xu, Xin; Ji, Peng; Yu, Yang; Cao, Biyin; Han, Kunkun; Hou, Tingjun; Xu, Zhuan; Kong, Yan; Jiang, Gaofeng; Tang, Xiaowen; Qiao, Chunhua; Mao, Xinliang

    2016-01-01

    The oncogenic STAT3 signaling pathway is emerging as a promising target for the treatment of multiple myeloma (MM). In the present study, we identified a novel STAT3 inhibitor SC99 in a target-based high throughput screen. SC99 inhibited JAK2-STAT3 activation but had no effects on other transcription factors such as NF-κB, and kinases such as AKT, ERK, and c-Src that are in association with STAT3 signaling pathway. Furthermore, SC99 downregulated the expression of STAT3-modulated genes, including Bcl-2, Bcl-xL, VEGF, cyclin D2, and E2F-1. By inhibiting the STAT3 signaling, SC99 induced MM cell apoptosis which could be partly abolished by the ectopic expression of STAT3. Furthermore, SC99 displayed potent anti-MM activity in two independent MM xenograft models in nude mice. Oral administration of SC99 led to marked decrease of tumor growth within 10 days at a daily dosage of 30 mg/kg, but did not raise toxic effects. Taken together, this study identified a novel oral JAK2/STAT3 inhibitor that could be developed as an anti-myeloma agent. PMID:26814430

  11. Bioinformatic analyses reveal a distinct Notch activation induced by STAT3 phosphorylation in the mesenchymal subtype of glioblastoma.

    PubMed

    Cheng, Wen; Zhang, Chuanbao; Ren, Xiufang; Jiang, Yang; Han, Sheng; Liu, Yang; Cai, Jinquan; Li, Mingyang; Wang, Kuanyu; Liu, Yanwei; Hu, Huimin; Li, Qingbin; Yang, Pei; Bao, Zhaoshi; Wu, Anhua

    2017-01-01

    OBJECTIVE Glioblastoma (GBM) is the most common and lethal type of malignant glioma. The Cancer Genome Atlas divides the gene expression-based classification of GBM into classical, mesenchymal, neural, and proneural subtypes, which is important for understanding GBM etiology and for designing effective personalized therapy. Signal transducer and activator of transcription 3 (STAT3), a critical transcriptional activator in tumorigenesis, is persistently phosphorylated and associated with an unfavorable prognosis in GBM. Although a set of specific targets has been identified, there have been no systematic analyses of STAT3 signaling based on GBM subtype. METHODS This study compared STAT3-associated messenger RNA, protein, and microRNA expression profiles across different subtypes of GBM. RESULTS The analyses revealed a prominent role for STAT3 in the mesenchymal but not in other GBM subtypes, which can be reliably used to classify patients with mesenchymal GBM into 2 groups according to phosphorylated STAT3 expression level. Differentially expressed genes suggest an association between Notch and STAT3 signaling in the mesenchymal subtype. Their association was validated in the U87 cell, a malignant glioma cell line annotated as mesenchymal subtype. Specific associated proteins and microRNAs further profile the STAT3 signaling among GBM subtypes. CONCLUSIONS These findings suggest a prominent role for STAT3 signaling in mesenchymal GBM and highlight the importance of identifying signaling pathways that contribute to specific cancer subtypes.

  12. Avicin D: A Protein Reactive Plant Isoprenoid Dephosphorylates Stat 3 by Regulating Both Kinase and Phosphatase Activities

    PubMed Central

    Haridas, Valsala; Nishimura, Goshi; Xu, Zhi-Xiang; Connolly, Fiona; Hanausek, Margaret; Walaszek, Zbigniew; Zoltaszek, Robert; Gutterman, Jordan U.

    2009-01-01

    Avicins, a class of electrophilic triterpenoids with pro-apoptotic, anti-inflammatory and antioxidant properties, have been shown to induce redox-dependant post-translational modification of cysteine residues to regulate protein function. Based on (a) the cross-talk that occurs between redox and phosphorylation processes, and (b) the role of Stat3 in the process of apoptosis and carcinogenesis, we chose to study the effects of avicins on the processes of phosphorylation/dephosphorylation in Stat3. Avicins dephosphorylate Stat3 in a variety of human tumor cell lines, leading to a decrease in the transcriptional activity of Stat3. The expression of Stat3-regulated proteins such as c-myc, cyclin D1, Bcl2, survivin and VEGF were reduced in response to avicin treatment. Underlying avicin-induced dephosphorylation of Stat3 was dephosphorylation of JAKs, as well as activation of protein phosphatase-1. Downregulation of both Stat3 activity and expression of Stat 3-controlled pro-survival proteins, contributes to the induction of apoptosis in avicin treated tumor cells. Based on the role of Stat3 in inflammation and wounding, and the in vivo inhibition of VEGF by avicins in a mouse skin carcinogenesis model, it is likely that avicin-induced inhibition of Stat3 activity results in the suppression of the pro-inflammatory and pro-oxidant stromal environment of tumors. Activation of PP-1, which also acts as a cellular economizer, combined with the redox regulation by avicins, can aid in redirecting metabolism from growth promoting anabolic to energy sparing pathways. PMID:19440292

  13. Mesenchymal stem cells promote osteosarcoma cell survival and drug resistance through activation of STAT3

    PubMed Central

    Liu, Shen; Wang, Lei; Fan, Qiming; Hao, Yongqiang; Fan, Cunyi; Tang, Ting-Ting

    2016-01-01

    Increasing evidence suggests that the tumor microenvironment plays a key role in the development of drug resistant tumor cells. In this study, we tried to determine whether the mesenchymal stem cells (MSCs) in the tumor microenvironment contribute to the increased chemoresistance of osteosarcoma. We found that exposure of Saos-2 and U2-OS cells to MSCs conditioned medium (CM) increased the viable cells in the presence of therapeutic concentrations of doxorubicin or cisplatin. Meanwhile, the MSC CM-associated pro-proliferative effects were accompanied by reduced caspase 3/7 activity and Annexin V binding. We confirmed that STAT3 activation by IL-6 regulates MSCs-induced chemoresistance. Blockade of this signal re-sensitized drug-resistant Saos-2 cells to drug treatment. Using a osteosarcoma mouse model with co-injection of MSCs with Saos-2cells, we found that inhibition of STAT3 prolonged the survival time of tumor bearing mice by suppressing tumor growth and increasing the sensitivity of tumor cells to doxorubicin. Finally, we demonstrated that increased expression of p-STAT3, multidrug resistance protein (MRP) and P-glycoprotein (MDR-1) was associated with high chemotherapy resistance in clinical osteosarcoma samples. Collectively, our findings suggest that MSCs within the tumor microenvironment may represent a new target to enhance chemotherapeutic efficacy in osteosarcoma patients. PMID:27340780

  14. Atrazine promotes RM1 prostate cancer cell proliferation by activating STAT3 signaling.

    PubMed

    Hu, Kebang; Tian, Yong; Du, Yanwei; Huang, Liandi; Chen, Junyu; Li, Na; Liu, Wei; Liang, Zuowen; Zhao, Lijing

    2016-05-01

    Atrazine, a widely used pesticide, is frequently detected in soil and surface water, which alarms epidemiologists and medical professionals because of its potential deleterious effects on health. Indeed, atrazine is a potent endocrine disruptor that increases aromatase expression in some human cancer cell lines. Both animal and human studies have suggested that atrazine is possibly carcinogenic, although discrepant results have been reported. In this study, RM1 cells were used to explore the atrazine effects on prostate cancer. Proliferation, migration and invasion of RM1 cells were assessed by colony formation, wound-healing and invasion assays, respectively, after in vitro exposure to atrazine. In addition, an RM1 cell xenograft model was generated to evaluate the effects of atrazine in vivo. To explore the molecular mechanisms, qRT‑PCR, immunohistochemistry, and western blot analyses were employed to detect mRNA and protein levels of STAT3 signaling and cell cycle related proteins, including p53, p21, cyclin B1 and cyclin D1. Interestingly, RM1 cell proliferation was increased after treatment with atrazine, concomitantly with STAT3 signaling activation. These results suggest that atrazine promotes RM1 cell growth in vitro and in vivo by activating STAT3 signaling.

  15. Nutritional control of IL-23/Th17-mediated autoimmune disease through HO-1/STAT3 activation

    PubMed Central

    Brück, Jürgen; Holstein, Julia; Glocova, Ivana; Seidel, Ursula; Geisel, Julia; Kanno, Toshio; Kumagai, Jin; Mato, Naoko; Sudowe, Stephan; Widmaier, Katja; Sinnberg, Tobias; Yazdi, Amir S.; Eberle, Franziska C.; Hirahara, Kiyoshi; Nakayama, Toshinori; Röcken, Martin; Ghoreschi, Kamran

    2017-01-01

    The nutritional curcumin (CUR) is beneficial in cell-mediated autoimmune diseases. The molecular mechanisms underlying this food-mediated silencing of inflammatory immune responses are poorly understood. By investigating antigen-specific immune responses we found that dietary CUR impairs the differentiation of Th1/Th17 cells in vivo during encephalomyelitis and instead promoted Th2 cells. In contrast, feeding CUR had no inhibitory effect on ovalbumin-induced airway inflammation. Mechanistically, we found that CUR induces an anti-inflammatory phenotype in dendritic cells (DC) with enhanced STAT3 phosphorylation and suppressed expression of Il12b and Il23a. On the molecular level CUR readily induced NRF2-sensitive heme oxygenase 1 (HO-1) mRNA and protein in LPS-activated DC. HO-1 enhanced STAT3 phosphorylation, which enriched to Il12b and Il23a loci and negatively regulated their transcription. These findings demonstrate the underlying mechanism through which a nutritional can interfere with the immune response. CUR silences IL-23/Th17-mediated pathology by enhancing HO-1/STAT3 interaction in DC. PMID:28290522

  16. STAT3 activation in Th17 and Th22 cells controls IL-22-mediated epithelial host defense during infectious colitis.

    PubMed

    Backert, Ingo; Koralov, Sergei B; Wirtz, Stefan; Kitowski, Vera; Billmeier, Ulrike; Martini, Eva; Hofmann, Katharina; Hildner, Kai; Wittkopf, Nadine; Brecht, Katrin; Waldner, Maximilian; Rajewsky, Klaus; Neurath, Markus F; Becker, Christoph; Neufert, Clemens

    2014-10-01

    The Citrobacter rodentium model mimics the pathogenesis of infectious colitis and requires sequential contributions from different immune cell populations, including innate lymphoid cells (ILCs) and CD4(+) lymphocytes. In this study, we addressed the role of STAT3 activation in CD4(+) cells during host defense in mice against C. rodentium. In mice with defective STAT3 in CD4(+) cells (Stat3(ΔCD4)), the course of infection was unchanged during the innate lymphoid cell-dependent early phase, but significantly altered during the lymphocyte-dependent later phase. Stat3(ΔCD4) mice exhibited intestinal epithelial barrier defects, including downregulation of antimicrobial peptides, increased systemic distribution of bacteria, and prolonged reduction in the overall burden of C. rodentium infection. Immunomonitoring of lamina propria cells revealed loss of virtually all IL-22-producing CD4(+) lymphocytes, suggesting that STAT3 activation was required for IL-22 production not only in Th17 cells, but also in Th22 cells. Notably, the defective host defense against C. rodentium in Stat3(∆CD4) mice could be fully restored by specific overexpression of IL-22 through a minicircle vector-based technology. Moreover, expression of a constitutive active STAT3 in CD4(+) cells shaped strong intestinal epithelial barrier function in vitro and in vivo through IL-22, and it promoted protection from enteropathogenic bacteria. Thus, our work indicates a critical role of STAT3 activation in Th17 and Th22 cells for control of the IL-22-mediated host defense, and strategies expanding STAT3-activated CD4(+) lymphocytes may be considered as future therapeutic options for improving intestinal barrier function in infectious colitis.

  17. Activation of the GP130-STAT3 axis and its potential implications in nonalcoholic fatty liver disease

    PubMed Central

    Min, Hae-Ki; Mirshahi, Faridoddin; Verdianelli, Aurora; Pacana, Tommy; Patel, Vaishali; Park, Chun-Geon; Choi, Aejin; Lee, Jeong-Hoon; Park, Chung-Berm; Ren, Shunlin

    2015-01-01

    The status of the GP130-STAT3 signaling pathway in humans with nonalcoholic fatty liver disease (NAFLD) and its relevance to disease pathogenesis are unknown. The expression of the gp130-STAT3 axis and gp130 cytokine receptors were studied in subjects with varying phenotypes of NAFLD including nonalcoholic steatohepatitis (NASH) and compared with lean and weight-matched controls without NAFLD. Gp130 and its downstream signaling element (Tyk2 and STAT3) expression were inhibited in obese controls whereas they were increased in NAFLD. IL-6 levels were increased in NASH and correlated with gp130 expression (P < 0.01). Palmitate inhibited gp130-STAT3 expression and signaling. IL-6 and palmitate inhibited hepatic insulin signaling via STAT3-dependent and independent mechanisms, respectively. STAT3 overexpression reversed palmitate-induced lipotoxicity by increasing autophagy (ATG7) and decreasing endoplasmic reticulum stress. These data demonstrate that the STAT3 pathway is activated in NAFLD and can worsen insulin resistance while protecting against other lipotoxic mechanisms of disease pathogenesis. PMID:25747354

  18. CD45 Phosphatase Inhibits STAT3 Transcription Factor Activity in Myeloid Cells and Promotes Tumor-Associated Macrophage Differentiation.

    PubMed

    Kumar, Vinit; Cheng, Pingyan; Condamine, Thomas; Mony, Sridevi; Languino, Lucia R; McCaffrey, Judith C; Hockstein, Neil; Guarino, Michael; Masters, Gregory; Penman, Emily; Denstman, Fred; Xu, Xiaowei; Altieri, Dario C; Du, Hong; Yan, Cong; Gabrilovich, Dmitry I

    2016-02-16

    Recruitment of monocytic myeloid-derived suppressor cells (MDSCs) and differentiation of tumor-associated macrophages (TAMs) are the major factors contributing to tumor progression and metastasis. We demonstrated that differentiation of TAMs in tumor site from monocytic precursors was controlled by downregulation of the activity of the transcription factor STAT3. Decreased STAT3 activity was caused by hypoxia and affected all myeloid cells but was not observed in tumor cells. Upregulation of CD45 tyrosine phosphatase activity in MDSCs exposed to hypoxia in tumor site was responsible for downregulation of STAT3. This effect was mediated by the disruption of CD45 protein dimerization regulated by sialic acid. Thus, STAT3 has a unique function in the tumor environment in controlling the differentiation of MDSC into TAM, and its regulatory pathway could be a potential target for therapy.

  19. Eudesmane-type sesquiterpenoids from Salvia plebeia inhibit IL-6-induced STAT3 activation.

    PubMed

    Jang, Hyun-Jae; Oh, Hyun-Mee; Hwang, Joo Tae; Kim, Mi-Hwa; Lee, Soyoung; Jung, Kyungsook; Kim, Young-Ho; Lee, Seung Woong; Rho, Mun-Chual

    2016-10-01

    Seven eudesmane-type sesquiterpenoid lactones and the known plebeiolide C were isolated from an ethanol-soluble extract of the aerial parts of Salvia plebeia R. Br. Their structures were determined via NMR and MS, and their absolute configurations were elucidated using ECD, and X-ray crystallographic analysis, as well as the modified Mosher ester method. All isolates were evaluated for their inhibitory effects on IL6-induced STAT3 promoter activation in stably transfected Hep3B cells. Of these isolates, eudebeiolide D exhibited an inhibitory effect with the IC50 value of 1.1 μM.

  20. PTEN ameliorates autoimmune arthritis through down-regulating STAT3 activation with reciprocal balance of Th17 and Tregs

    PubMed Central

    Lee, Seung Hoon; Park, Jin-Sil; Byun, Jae-Kyung; Jhun, JooYeon; Jung, KyungAh; Seo, Hyeon-Beom; Moon, Young-Mee; Kim, Ho-Youn; Park, Sung-Hwan; Cho, Mi-La

    2016-01-01

    PTEN is a tyrosine phosphatase with significant function in inhibiting STAT3 activation. Recently, inactivation of STAT3 has been demonstrated as a therapeutic candidate for autoimmune arthritis. The expression of PTEN controlled by p53 regulates autoimmune arthritis through modulating the balance between Th17 and Treg. We hypothesized that PTEN regulated by p53 might reduce CIA severity and inflammatory response via inhibiting STAT3 activation. Our results revealed that PTEN could ameliorate experimental autoimmune arthritis by reducing STAT3 activity and Th17 differentiation. Systemic infusion of PTEN overexpression downregulated CIA severity. In addition, PTEN overexpression decreased the activation of T cells and modulated reciprocal differentiation of Th17 and Treg cells. We observed that PTEN expression downregulated by p53 deficiency induced the activation of STAT3. Loss of p53 exacerbated autoimmune arthritis and dysregulated the population of Th17 and Treg. These data suggest that induction of STAT3-modulatory activity of PTEN may be a therapeutic target for rheumatoid arthritis therapy. PMID:27708408

  1. PTEN ameliorates autoimmune arthritis through down-regulating STAT3 activation with reciprocal balance of Th17 and Tregs.

    PubMed

    Lee, Seung Hoon; Park, Jin-Sil; Byun, Jae-Kyung; Jhun, JooYeon; Jung, KyungAh; Seo, Hyeon-Beom; Moon, Young-Mee; Kim, Ho-Youn; Park, Sung-Hwan; Cho, Mi-La

    2016-10-06

    PTEN is a tyrosine phosphatase with significant function in inhibiting STAT3 activation. Recently, inactivation of STAT3 has been demonstrated as a therapeutic candidate for autoimmune arthritis. The expression of PTEN controlled by p53 regulates autoimmune arthritis through modulating the balance between Th17 and Treg. We hypothesized that PTEN regulated by p53 might reduce CIA severity and inflammatory response via inhibiting STAT3 activation. Our results revealed that PTEN could ameliorate experimental autoimmune arthritis by reducing STAT3 activity and Th17 differentiation. Systemic infusion of PTEN overexpression downregulated CIA severity. In addition, PTEN overexpression decreased the activation of T cells and modulated reciprocal differentiation of Th17 and Treg cells. We observed that PTEN expression downregulated by p53 deficiency induced the activation of STAT3. Loss of p53 exacerbated autoimmune arthritis and dysregulated the population of Th17 and Treg. These data suggest that induction of STAT3-modulatory activity of PTEN may be a therapeutic target for rheumatoid arthritis therapy.

  2. Glutamine activates STAT3 to control cancer cell proliferation independently of glutamine metabolism.

    PubMed

    Cacace, A; Sboarina, M; Vazeille, T; Sonveaux, P

    2017-04-01

    Cancer cells can use a variety of metabolic substrates to fulfill the bioenergetic and biosynthetic needs of their oncogenic program. Besides bioenergetics, cancer cell metabolism also directly influences genetic, epigenetic and signaling events associated with tumor progression. Many cancer cells are addicted to glutamine, and this addiction is observed in oxidative as well as in glycolytic cells. Although both oxidative and bioreductive glutamine metabolism can contribute to cancer progression and glutamine can further serve to generate peptides (including glutathione) and proteins, we report that glutamine promotes the proliferation of cancer cells independently of its use as a metabolic fuel or as a precursor of glutathione. Extracellular glutamine activates transcription factor signal transducer and activator of transcription 3 (STAT3), which is necessary and sufficient to mediate the proliferative effects of glutamine on glycolytic and oxidative cancer cells. Glutamine also activates transcription factors hypoxia-inducible factor-1, mammalian target of rapamycin and c-Myc, but these factors do not mediate the effects of glutamine on cancer cell proliferation. Our findings shed a new light on the anticancer effects of l-asparaginase that possesses glutaminase activity and converts glutamine into glutamate extracellularly. Conversely, cancer resistance to treatments that block glutamine metabolism could arise from glutamine-independent STAT3 reactivation.

  3. Pien Tze Huang suppresses IL-6-inducible STAT3 activation in human colon carcinoma cells through induction of SOCS3.

    PubMed

    Shen, Aling; Chen, Youqin; Hong, Fei; Lin, Jiumao; Wei, Lihui; Hong, Zhenfeng; Sferra, Thomas J; Peng, Jun

    2012-12-01

    IL-6/STAT3 is one of the most critical cellular signal transduction pathways known to malfunction in colorectal cancer (CRC). As a target gene of signal transducer and activator of transcription 3 (STAT3) signaling, suppressor of cytokine signaling 3 (SOCS3) can be quickly induced by interleukin-6 (IL-6) stimulation but it then strongly inhibits IL-6-mediated STAT3 activation, functioning as a negative feedback regulator of the IL-6/STAT3 pathway. Aberrant activation of STAT3 and/or reduced expression of SOCS are strongly correlated with carcinogenesis, which therefore becomes a promising target for the development of novel anticancer chemotherapies. Pien Tze Huang (PZH) is a well-known traditional Chinese formula that was first prescribed by a royal physician 450 years ago in the Ming Dynasty. It has been used in China and Southeast Asia for centuries as a folk remedy for various types of cancer including CRC. However, the precise mechanism of its antitumor activity remains largely unclear. In the present study, we found that PZH could significantly and dose-dependently inhibit IL-6-mediated increase of STAT3 phosphorylation levels and transcriptional activity in the human colon carcinoma HT-29 cells, resulting in the suppression of cell proliferation and the induction of apoptosis. In addition, PZH treatment profoundly inhibited IL-6-induced upregulation of cyclin D1 and Bcl-2, two key target genes of the STAT3 pathway. Moreover, PZH treatment increased the expression of SOCS3. These results suggest that PZH could effectively inhibit proliferation and promote apoptosis of human colon carcinoma cells via modulation of the IL-6/STAT3 signaling pathway and its target genes.

  4. Predominant Activation of JAK/STAT3 Pathway by Interleukin-6 Is Implicated in Hepatocarcinogenesis.

    PubMed

    Jung, In Hye; Choi, Jeffrey Hyun-Kyu; Chung, Yong-Yoon; Lim, Ga-Lam; Park, Young-Nyun; Park, Seung Woo

    2015-07-01

    Chronic inflammation is an important process leading to tumorigenesis. Therefore, targeting and controlling inflammation can be a promising cancer therapy. Inflammation is often caused by a variety of inflammatory cytokine such as the interleukin (IL)-6, a pleiotrophic cytokine known to be involved in the tumorigenesis. In this study, an in vivo hepatic tumorigenesis model of zebrafish was generated to demonstrate a direct consequence of the human IL6 expression causing hepatocarcinogenesis. To do this, an elevated expression of the hIL6 gene was established to specifically target the zebrafish hepatocytes by transgenesis. Interestingly, the elevated hIL6 expression caused the chronic inflammation which results in a massive infiltration of inflammatory cells. This eventually resulted in the generation of various dysplastic lesions such as clear cell, small cell, and large cell changes, and also eosinophilic and basophilic foci of hepatocellular alteration. Hepatocellular carcinoma was then developed in the transgenic zebrafish. Molecular characterization revealed upregulation of the downstream components involved in the IL6-mediated signaling pathways, especially PI3K/Akt and JAK/STAT3 pathways. Further investigation indicated that PI3K was the most reactive to the infiltrated inflammatory cells and dysplasia with large cell change, whereas STAT3 was heavily activated in the region with dysplastic foci, suggesting that the JAK/STAT3 pathway was mainly implicated in the hepatic tumorigenesis in the current model. Our present study provides an in vivo evidence of the relationship between chronic inflammation and tumorigenesis and reinforces the pivotal role of IL6 in the inflammation-associated hepatocarcinogenesis.

  5. Xanthohumol inhibits STAT3 activation pathway leading to growth suppression and apoptosis induction in human cholangiocarcinoma cells.

    PubMed

    Dokduang, Hasaya; Yongvanit, Puangrat; Namwat, Nisana; Pairojkul, Chawalit; Sangkhamanon, Sakkarn; Yageta, Mika Sakurai; Murakami, Yoshinori; Loilome, Watcharin

    2016-04-01

    STAT3 plays a significant role in the development of cholangiocarcinoma (CCA) associated with the liver fluke (Opisthorchis viverrini; Ov). Xanthohumol (XN), a prenylated flavonoid extracted from hops, has known anticancer activity and could potentially target STAT3. The present study determined the effect of XN on STAT3, as well as ascertained its usefulness against CCA. The CCA cell proliferation at 20 µM and 50 µM of XN was shown to inhibited, while 20 µM partially inhibited IL-6-induced STAT3 activation. At 50 µM, the inhibition was complete. The reduction in STAT3 activity at 20 and 50 µM was associated with a significant reduction of CCA cell growth and apoptosis. We also found that the administration of 50 µM XN orally in drinking water to nude mice inoculated with CCA led to a reduction in tumor growth in comparison with controls. In addition, apoptosis of cancer cells increased although there was no visible toxicity. The present study shows that XN can inhibit STAT3 activation both in vivo and in vitro due to suppression of the Akt-NFκB signaling pathway. XN should be considered as a possible therapeutic agent against CCA.

  6. Signal transducer and activator of transcription (STAT)-3 regulates microRNA gene expression in chronic lymphocytic leukemia cells

    PubMed Central

    2013-01-01

    Backgrounds Approximately 1,000 microRNAs (miRs) are present in the human genome; however, little is known about the regulation of miR transcription. Because miR levels are deregulated in chronic lymphocytic leukemia (CLL) and signal transducer and activator of transcription (STAT)-3 is constitutively activated in CLL, we sought to determine whether STAT3 affects the transcription of miR genes in CLL cells. Methods We used publically available data from the ENCODE project to identify putative STAT3 binding sites in the promoters of miR genes. Then we transfected CLL cells with STAT3-shRNA or with an empty vector, and to determine which miRs are differentially expressed, we used a miR microarray approach followed by validation of the microarray results for 6 miRs using quantitative real-time polymerase chain reaction (qRT-PCR). Results We identified putative STAT3 binding sites in 160 promoter regions of 200 miRs, including miR-21, miR-29, and miR-155, whose levels have been reported to be upregulated in CLL. Levels of 72 miRs were downregulated (n = 63) or upregulated (n = 9). qRT-PCR confirmed the array data in 5 of 6 miRs. Conclusions The presence of activated STAT3 has a profound effect on miR expression in CLL cells. PMID:23725032

  7. Icaritin, a novel FASN inhibitor, exerts anti-melanoma activities through IGF-1R/STAT3 signaling

    PubMed Central

    Wu, Jinfeng; Du, Juan; Fu, Xiuqiong; Liu, Bin; Cao, Huihui; Li, Ting; Su, Tao; Xu, Jinhua; Tse, Anfernee Kai-Wing; Yu, Zhi-Ling

    2016-01-01

    Icaritin (IT) is a flavonoid isolated from Herba Epimedii. In this study, we evaluated the anti-melanoma activities of IT, and determined its cytotoxic mechanism. We found that IT exerted cytotoxicity to melanoma cells. Furthermore, IT induced melanoma cell apoptosis, which was accompanied with PARP cleavage. Mechanistically, IT suppressed p-STAT3 (tyr705) level in parallel with increases of p-STAT3 (ser727), p-ERK and p-AKT. IT significantly inhibited STAT3 nuclear translocation and reduced the levels of STAT3 -targeted genes. IT also inhibited IGF-1-induced STAT3 activation through down-regulation of total IGF-1R level. No dramatic changes in IGF-1R mRNA levels were observed in IT-treated cells, suggesting that IT acted primarily at a post-transcriptional level. Using molecular docking analysis, IT was identified as a novel fatty acid synthase (FASN) inhibitor. We found that IT reduced the level of total IGF-1R via FASN inhibition. In summary, we reported that IT exerted anti-melanoma activities, and these effects were partially due to inhibition of FASN/IGF-1R/STAT3 signaling. PMID:27323414

  8. Hes1 Desynchronizes Differentiation of Pluripotent Cells by Modulating STAT3 Activity

    PubMed Central

    Zhou, Xinzhi; Smith, Andrew JH; Waterhouse, Anna; Blin, Guillaume; Malaguti, Mattias; Lin, Chia-Yi; Osorno, Rodrigo; Chambers, Ian; Lowell, Sally

    2013-01-01

    Robust development of the early embryo may benefit from mechanisms that ensure that not all pluripotent cells differentiate at exactly the same time: such mechanisms would build flexibility into the process of lineage allocation. This idea is supported by the observation that pluripotent stem cells differentiate at different rates in vitro. We use a clonal commitment assay to confirm that pluripotent cells commit to differentiate asynchronously even under uniform differentiation conditions. Stochastic variability in expression of the Notch target gene Hes1 has previously been reported to influence neural versus mesodermal differentiation through modulation of Notch activity. Here we report that Hes1 also has an earlier role to delay exit from the pluripotent state into all lineages. The early function of Hes1 to delay differentiation can be explained by an ability of Hes1 to amplify STAT3 responsiveness in a cell-autonomous manner. Variability in Hes1 expression therefore helps to explain why STAT3 responsiveness varies between individual ES cells, and this in turn helps to explain why pluripotent cells commit to differentiate asynchronously. Stem Cells 2013;31:1511–1522 PMID:23649667

  9. Hes1 desynchronizes differentiation of pluripotent cells by modulating STAT3 activity.

    PubMed

    Zhou, Xinzhi; Smith, Andrew J H; Waterhouse, Anna; Blin, Guillaume; Malaguti, Mattias; Lin, Chia-Yi; Osorno, Rodrigo; Chambers, Ian; Lowell, Sally

    2013-08-01

    Robust development of the early embryo may benefit from mechanisms that ensure that not all pluripotent cells differentiate at exactly the same time: such mechanisms would build flexibility into the process of lineage allocation. This idea is supported by the observation that pluripotent stem cells differentiate at different rates in vitro. We use a clonal commitment assay to confirm that pluripotent cells commit to differentiate asynchronously even under uniform differentiation conditions. Stochastic variability in expression of the Notch target gene Hes1 has previously been reported to influence neural versus mesodermal differentiation through modulation of Notch activity. Here we report that Hes1 also has an earlier role to delay exit from the pluripotent state into all lineages. The early function of Hes1 to delay differentiation can be explained by an ability of Hes1 to amplify STAT3 responsiveness in a cell-autonomous manner. Variability in Hes1 expression therefore helps to explain why STAT3 responsiveness varies between individual ES cells, and this in turn helps to explain why pluripotent cells commit to differentiate asynchronously.

  10. Obox4-silencing-activated STAT3 and MPF/MAPK signaling accelerate nuclear membrane breakdown in mouse oocytes.

    PubMed

    Lee, Hyun-Seo; Kim, Kyeoung-Hwa; Kim, Eun-Young; Lee, Su-Yeon; Ko, Jung-Jae; Lee, Kyung-Ah

    2016-04-01

    Mouse oocytes begin to mature in vitro once liberated from ovarian follicles. Previously, we showed that oocyte-specific homeobox 4 (Obox4) is critical for maintaining the intact nuclear membrane of the germinal vesicle (GV) in oocytes and for completing meiosis at the metaphase I-II (MI-MII) transition. This study further examines the molecular mechanisms of OBOX4 in regulating GV nuclear membrane breakdown. Maturation-promoting factor (MPF) and MAPK are normally inactive in GV stage oocytes but were activated prematurely in arrested GV stage oocytes by 3-isobutyl-1-metyl-xanthine (IBMX) in vitro after Obox4 RNA interference (RNAi). Furthermore, signal transducer and activator of transcription 3 (STAT3) was significantly activated by Obox4 RNAi. We confirmed that this Obox4 RNAi-induced premature STAT3 and MPF/MAPK activation at the GV stage provoked subsequent GV breakdown (GVBD) despite the opposing force of high cAMP in the IBMX-supplemented medium to maintain intact GV. When cumulus-oocyte complexes were exposed to interferon α (IFNA), a STAT3 activator, oocytes matured and cumulus cells expanded to resume nuclear maturation in IBMX-supplemented medium, suggesting that STAT3 activation is sufficient for stimulating the continuation of meiosis. Using Stattic, a specific STAT3 inhibitor, we confirmed that GVBD involves STAT3 activation in Obox4-silenced oocytes. Based on these findings, we concluded that i) Obox4 is an important upstream regulator of MPF/MAPK and STAT3 signaling, and ii) Obox4 is a key regulator of the GV arrest mechanism in oocytes.

  11. Dimethylfumarate suppresses adipogenic differentiation in 3T3-L1 preadipocytes through inhibition of STAT3 activity.

    PubMed

    Kang, Hyeon-Ji; Seo, Hyun-Ae; Go, Younghoon; Oh, Chang Joo; Jeoung, Nam Ho; Park, Keun-Gyu; Lee, In-Kyu

    2013-01-01

    The excessive accumulation of adipocytes contributes to the development of obesity and obesity-related diseases. The interactions of several transcription factors, such as C/EBPβ, PPARγ, C/EBPα, Nrf2, and STAT3, are required for adipogenic differentiation. Dimethylfumarate (DMF), an immune modulator and antioxidant, may function as an inhibitor of STAT3 and an activator of Nrf2. This study examined whether DMF inhibits adipogenic differentiation of 3T3-L1 preadipocytes by inhibiting STAT3 or activating Nrf2. DMF suppressed 3T3-L1 preadipocyte differentiation to mature adipocytes in a dose-dependent manner as determined by Oil Red O staining. The mRNA and protein levels of adipogenic genes, including C/EBPβ, C/EBPα, PPARγ, SREBP-1c, FAS, and aP2, were significantly lower in DMF-treated 3T3-L1 preadipocytes. Suppression of adipogenic differentiation by DMF treatment resulted primarily from inhibition of the early stages of differentiation. DMF inhibits clonal expansion during adipogenic differentiation through induction of a G1 cell cycle arrest. Additionally, DMF regulates cell cycle-related proteins, such as p21, pRb, and cyclin D. DMF treatment markedly inhibited differentiation medium-induced STAT3 phosphorylation and inhibited STAT3 transcriptional activation of a reporter construct composed of four synthetic STAT3-response elements. Moreover, inhibition of endogenous Nrf2 activity using a dominant negative Nrf2 did not abolish the DMF-induced inhibition of adipogenic differentiation of 3T3-L1 preadipocytes. In summary, DMF is a negative regulator of adipogenic differentiation based on its regulation of adipogenic transcription factors and cell cycle proteins. This negative regulation by DMF is mediated by STAT3 inhibition, but is unlikely to involve Nrf2 activation.

  12. MicroRNA-199a-5p promotes tumour growth by dual-targeting PIAS3 and p27 in human osteosarcoma

    PubMed Central

    Wang, Chen; Ba, Ximing; Guo, Yu; Sun, Defang; Jiang, Haoyang; Li, Wentao; Huang, Zhen; Zhou, Guangxin; Wu, Sujia; Zhang, Junfeng; Chen, Jiangning

    2017-01-01

    Osteosarcoma (OS) is the most common primary bone malignancy and remains a leading cause of cancer-related deaths in adolescents. Emerging evidence indicates that microRNAs (miRNAs) are correlated with clinical and biological characteristics of OS. However, the involvement of miR-199a-5p in OS development remains unclear. In this study, we examined the function of miR-199a-5p in vitro and in vivo. The results showed that miR-199a-5p was significantly up-regulated in OS patient tissues and cells. The inhibition of miR-199a-5p led to a significant decrease in cell proliferation and tumour growth. We further demonstrated that miR-199a-5p could directly bind to the 3′UTRs of the mRNA of both PIAS3 and p27 and mediate a decrease in the protein levels of PIAS3 and p27, thereby stimulating STAT3 activation and cell cycle progression in OS cells. Rescue experiments of PIAS3 and p27 further revealed that PIAS3 and p27 were functional targets of miR-199a-5p. Moreover, enhancing the expressions of both PIAS3 and p27 using miR-199a-5p-targeted inhibitors in an OS xenograft model was shown to be a promising approach for OS clinical therapy. Our findings indicate that the pathway of miR-199a-5p targeting both PIAS3 and p27 is a possible mechanism that contributes to tumour growth in OS. PMID:28120918

  13. Activation of Antitumorigenic Stat3beta in Breast Cancer by Splicing Redirection

    DTIC Science & Technology

    2013-07-01

    therapy. Nat Rev Cancer 2: 740-749. 3. Levy DE, Lee CK (2002) What does Stat3 do? J Clin Invest 109: 1143-1148. 4. Akira S ( 2000 ) Roles of STAT3 defined...breast cancer cells. Cancer Res 57: 978-987. 17. Inghirami G, Chiarle R, Simmons WJ, Piva R, Schlessinger K, et al. (2005) New and old functions of

  14. IL-15 Activates the Jak3/STAT3 Signaling Pathway to Mediate Glucose Uptake in Skeletal Muscle Cells.

    PubMed

    Krolopp, James E; Thornton, Shantaé M; Abbott, Marcia J

    2016-01-01

    Myokines are specialized cytokines that are secreted from skeletal muscle (SKM) in response to metabolic stimuli, such as exercise. Interleukin-15 (IL-15) is a myokine with potential to reduce obesity and increase lean mass through induction of metabolic processes. It has been previously shown that IL-15 acts to increase glucose uptake in SKM cells. However, the downstream signals orchestrating the link between IL-15 signaling and glucose uptake have not been fully explored. Here we employed the mouse SKM C2C12 cell line to examine potential downstream targets of IL-15-induced alterations in glucose uptake. Following differentiation, C2C12 cells were treated overnight with 100 ng/ml of IL-15. Activation of factors associated with glucose metabolism (Akt and AMPK) and known downstream targets of IL-15 (Jak1, Jak3, STAT3, and STAT5) were assessed with IL-15 stimulation. IL-15 stimulated glucose uptake and GLUT4 translocation to the plasma membrane. IL-15 treatment had no effect on phospho-Akt, phospho-Akt substrates, phospho-AMPK, phospho-Jak1, or phospho-STAT5. However, with IL-15, phospho-Jak3 and phospho-STAT3 levels were increased along with increased interaction of Jak3 and STAT3. Additionally, IL-15 induced a translocation of phospho-STAT3 from the cytoplasm to the nucleus. We have evidence that a mediator of glucose uptake, HIF1α, expression was dependent on IL-15 induced STAT3 activation. Finally, upon inhibition of STAT3 the positive effects of IL-15 on glucose uptake and GLUT4 translocation were abolished. Taken together, we provide evidence for a novel signaling pathway for IL-15 acting through Jak3/STAT3 to regulate glucose metabolism.

  15. TLR9-Targeted STAT3 Silencing Abrogates Immunosuppressive Activity of Myeloid-Derived Suppressor Cells from Prostate Cancer Patients

    PubMed Central

    Hossain, Dewan M. S.; Pal, Sumanta K.; Moreira, Dayson; Duttagupta, Priyanka; Zhang, Qifang; Won, Haejung; Jones, Jeremy; D'Apuzzo, Massimo; Forman, Stephen; Kortylewski, Marcin

    2015-01-01

    Purpose Recent advances in immunotherapy of advanced human cancers underscored the need to address and eliminate tumor immune evasion. The myeloid-derived suppressor cells (MDSCs) are important inhibitors of T cell responses in solid tumors, such as prostate cancers. However, targeting MDSCs proved challenging due to their phenotypic heterogeneity. Experimental Design Myeloid cell populations were evaluated using flow cytometry on blood samples, functional assays and immunohistochemical/immunofluorescent stainings on tumor/tumor-draining lymph node specimens from healthy subjects, localized and metastatic castration-resistant prostate cancer patients. Results Here, we identify a population of Lin−CD15HICD33LO granulocytic MDSCs that accumulate in patients’ circulation during prostate cancer progression from localized to metastatic disease. The prostate cancer-associated MDSCs potently inhibit autologous CD8+ T cells proliferation and production of IFNγ and Granzyme-B. The circulating MDSCs have high levels of activated STAT3, which is a central immune checkpoint regulator. The granulocytic pSTAT3+ cells are also detectable in patients’ prostate tissues. We previously generated an original strategy to silence genes specifically in Toll-like Receptor-9 (TLR9) positive myeloid cells using CpG-siRNA conjugates. We demonstrate that human granulocytic MDSCs express TLR9 and rapidly internalize naked CpG-STAT3siRNA thereby silencing STAT3 expression. STAT3 blocking abrogates immunosuppressive effects of patients-derived MDSCs on effector CD8+ T cells. These effects depended on reduced expression and enzymatic activity of Arginase-1, a downstream STAT3 target gene and a potent T cell inhibitor. Conclusions Overall, we demonstrate the accumulation of granulocytic MDSCs with prostate cancer progression and the feasibility of using TLR9-targeted STAT3siRNA delivery strategy to alleviate MDSC-mediated immunosuppression. PMID:25967142

  16. IL-15 Activates the Jak3/STAT3 Signaling Pathway to Mediate Glucose Uptake in Skeletal Muscle Cells

    PubMed Central

    Krolopp, James E.; Thornton, Shantaé M.; Abbott, Marcia J.

    2016-01-01

    Myokines are specialized cytokines that are secreted from skeletal muscle (SKM) in response to metabolic stimuli, such as exercise. Interleukin-15 (IL-15) is a myokine with potential to reduce obesity and increase lean mass through induction of metabolic processes. It has been previously shown that IL-15 acts to increase glucose uptake in SKM cells. However, the downstream signals orchestrating the link between IL-15 signaling and glucose uptake have not been fully explored. Here we employed the mouse SKM C2C12 cell line to examine potential downstream targets of IL-15-induced alterations in glucose uptake. Following differentiation, C2C12 cells were treated overnight with 100 ng/ml of IL-15. Activation of factors associated with glucose metabolism (Akt and AMPK) and known downstream targets of IL-15 (Jak1, Jak3, STAT3, and STAT5) were assessed with IL-15 stimulation. IL-15 stimulated glucose uptake and GLUT4 translocation to the plasma membrane. IL-15 treatment had no effect on phospho-Akt, phospho-Akt substrates, phospho-AMPK, phospho-Jak1, or phospho-STAT5. However, with IL-15, phospho-Jak3 and phospho-STAT3 levels were increased along with increased interaction of Jak3 and STAT3. Additionally, IL-15 induced a translocation of phospho-STAT3 from the cytoplasm to the nucleus. We have evidence that a mediator of glucose uptake, HIF1α, expression was dependent on IL-15 induced STAT3 activation. Finally, upon inhibition of STAT3 the positive effects of IL-15 on glucose uptake and GLUT4 translocation were abolished. Taken together, we provide evidence for a novel signaling pathway for IL-15 acting through Jak3/STAT3 to regulate glucose metabolism. PMID:28066259

  17. Activation of the STAT3 Signaling Pathway Is Associated With Poor Survival in Diffuse Large B-Cell Lymphoma Treated With R-CHOP

    PubMed Central

    Huang, Xin; Meng, Bin; Iqbal, Javeed; Ding, B. Belinda; Perry, Anamarija M.; Cao, Wenfeng; Smith, Lynette M.; Bi, Chengfeng; Jiang, Chunsun; Greiner, Timothy C.; Weisenburger, Dennis D.; Rimsza, Lisa; Rosenwald, Andreas; Ott, German; Delabie, Jan; Campo, Elias; Braziel, Rita M.; Gascoyne, Randy D.; Cook, James R.; Tubbs, Raymond R.; Jaffe, Elaine S.; Armitage, James O.; Vose, Julie M.; Staudt, Louis M.; McKeithan, Timothy W.; Chan, Wing C.; Ye, B. Hilda; Fu, Kai

    2013-01-01

    Purpose We previously reported that constitutive STAT3 activation is a prominent feature of the activated B-cell subtype of diffuse large B-cell lymphomas (ABC-DLBCL). In this study, we investigated whether STAT3 activation can risk stratify patients with DLBCL. Patients and Methods By an immunohistochemical method, we investigated phosphotyrosine STAT3 (PY-STAT3) expression from 185 patients with DLBCL treated with R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone). Cell line-based siRNA experiments were also performed to generate an 11-gene, PY-STAT3 activation signature, which was used to study a previously published cohort of 222 patients with DLBCL. The STAT3 activation status determined by these two methods and by STAT3 mRNA levels were then correlated with survival. Results PY-STAT3 was detected in 37% of DLBCL and enriched in ABC-DLBCL cases (P = .03). PY-STAT3 positivity significantly correlated with poor overall survival (OS; P = .01) and event-free survival (EFS; P = .006). Similar observations were made for high levels of STAT3 mRNA. In multivariable analysis, PY-STAT3 status (P = .02), International Prognostic Index (P = .02), and BCL2 expression (P = .046) were independent prognosticators of OS in this cohort. Among the cell-of-origin subgroups, PY-STAT3 was associated with poor EFS among non–germinal center B-cell DLBCL cases only (P = .027). Similarly, the 11-gene STAT3 activation signature correlated with poor survival in the entire DLBCL cohort (OS, P < .001; EFS, P < .001) as well as the ABC-DLBCL subgroup (OS, P = .029; EFS, P = .025). Conclusion STAT3 activation correlated with poor survival in patients with DLBCL treated with R-CHOP, especially those with tumors of the ABC-DLBCL subtype. PMID:24220563

  18. Regulation of STAT3 and NF-κB activations by S-nitrosylation in multiple myeloma.

    PubMed

    Kim, Jinsu; Choi, Seungho; Saxena, Nishant; Singh, Avtar K; Singh, Inderjit; Won, Je-Seong

    2017-05-01

    Numerous reports suggest that aberrant activations of STAT3 and NF-κB promote survival and proliferation of multiple myeloma (MM) cells. In the present report, we demonstrate that a synthetic S-nitrosothiol compound, S-nitroso-N-acetylcysteine (SNAC), inhibits proliferation and survival of multiple MM cells via S-nitrosylation-dependent inhibition of STAT3 and NF-κB. In human MM cells (e.g. U266, H929, and IM-9 cells), SNAC treatment increased S-nitrosylation of STAT3 and NF-κB and inhibited their activities. Consequently, SNAC treatment resulted in MM cell cycle arrest at G1/S check point and inhibited their proliferation. SNAC also decreased the expression of cell survival factors and increased the activities of caspases, thus increased sensitivity of MM cells to melphalan, a chemotherapeutic agent for MM. In U266 xenografted mice, SNAC treatment decreased the activity of STAT3 and reduced the growth of human CD138 positive cells (U266 cells) in the bone marrow and also reduced their production of human IgE into the serum. Taken together, these data document the S-nitrosylation mediated inhibition of MM cell proliferation and cell survival via inhibition of STAT3 and NF-κB pathways and its efficacy in animal model of MM.

  19. Differential Pro-Inflammatory Responses of Astrocytes and Microglia Involve STAT3 Activation in Response to 1800 MHz Radiofrequency Fields

    PubMed Central

    Lu, Yonghui; He, Mindi; Zhang, Yang; Xu, Shangcheng; Zhang, Lei; He, Yue; Chen, Chunhai; Liu, Chuan; Pi, Huifeng; Yu, Zhengping; Zhou, Zhou

    2014-01-01

    Microglia and astrocytes play important role in maintaining the homeostasis of central nervous system (CNS). Several CNS impacts have been postulated to be associated with radiofrequency (RF) electromagnetic fields exposure. Given the important role of inflammation in neural physiopathologic processes, we investigated the pro-inflammatory responses of microglia and astrocytes and the involved mechanism in response to RF fields. Microglial N9 and astroglial C8-D1A cells were exposed to 1800 MHz RF for different time with or without pretreatment with STAT3 inhibitor. Microglia and astrocytes were activated by RF exposure indicated by up-regulated CD11b and glial fibrillary acidic protein (GFAP). However, RF exposure induced differential pro-inflammatory responses in astrocytes and microglia, characterized by different expression and release profiles of IL-1β, TNF-α, IL-6, PGE2, nitric oxide (NO), inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX2). Moreover, the RF exposure activated STAT3 in microglia but not in astrocytes. Furthermore, the STAT3 inhibitor Stattic ameliorated the RF-induced release of pro-inflammatory cytokines in microglia but not in astrocytes. Our results demonstrated that RF exposure differentially induced pro-inflammatory responses in microglia and astrocytes, which involved differential activation of STAT3 in microglia and astrocytes. Our data provide novel insights into the potential mechanisms of the reported CNS impacts associated with mobile phone use and present STAT3 as a promising target to protect humans against increasing RF exposure. PMID:25275372

  20. STAT3 activation is associated with cerebrospinal fluid interleukin-10 (IL-10) in primary central nervous system diffuse large B cell lymphoma.

    PubMed

    Mizowaki, Takashi; Sasayama, Takashi; Tanaka, Kazuhiro; Mizukawa, Katsu; Takata, Kumi; Nakamizo, Satoshi; Tanaka, Hirotomo; Nagashima, Hiroaki; Nishihara, Masamitsu; Hirose, Takanori; Itoh, Tomoo; Kohmura, Eiji

    2015-09-01

    Signal transducers and activators of transcription 3 (STAT3) are activated by various cytokines and oncogenes; however, the activity and pathogenesis of STAT3 in diffuse large B cell lymphoma of the central nervous system have not been thoroughly elucidated. We investigated the phosphorylation levels of STAT3 in 40 specimens of primary central nervous system diffuse large B-cell lymphoma (PCNS DLBCL) and analyzed the association between phsopho-STAT3 (pSTAT3) expression and cerebrospinal fluid (CSF) concentration of interleukin-10 (IL-10) or IL-6. Immunohistochemistry and Western blot analysis revealed that most of the specimens in PCNS DLBCL expressed pSTST3 protein, and a strong phosphorylation levels of STAT3 was statistically associated with high CSF IL-10 levels, but not with CSF IL-6 levels. Next, we demonstrated that recombinant IL-10 and CSF containing IL-10 induced the phosphorylation of STAT3 in PCNS DLBCL cells. Furthermore, molecular subtype classified by Hans' algorithm was correlated with pSTAT3 expression levels and CSF IL-10 levels. These results suggest that the STAT3 activity is correlated with CSF IL-10 level, which is a useful marker for STAT3 activity in PCNS DLBCLs.

  1. EBV Latent Membrane Protein 1 Activates Akt, NFκB, and Stat3 in B Cell Lymphomas

    PubMed Central

    Shair, Kathy H. Y; Bendt, Katherine M; Edwards, Rachel H; Bedford, Elisabeth C; Nielsen, Judith N; Raab-Traub, Nancy

    2007-01-01

    Latent membrane protein 1 (LMP1) is the major oncoprotein of Epstein-Barr virus (EBV). In transgenic mice, LMP1 promotes increased lymphoma development by 12 mo of age. This study reveals that lymphoma develops in B-1a lymphocytes, a population that is associated with transformation in older mice. The lymphoma cells have deregulated cell cycle markers, and inhibitors of Akt, NFκB, and Stat3 block the enhanced viability of LMP1 transgenic lymphocytes and lymphoma cells in vitro. Lymphoma cells are independent of IL4/Stat6 signaling for survival and proliferation, but have constitutively activated Stat3 signaling. These same targets are also deregulated in wild-type B-1a lymphomas that arise spontaneously through age predisposition. These results suggest that Akt, NFκB, and Stat3 pathways may serve as effective targets in the treatment of EBV-associated B cell lymphomas. PMID:17997602

  2. SC-2001 Overcomes STAT3-mediated Sorafenib Resistance through RFX-1/SHP-1 Activation in Hepatocellular Carcinoma☆☆☆

    PubMed Central

    Su, Jung-Chen; Tseng, Ping-Hui; Wu, Szu-Hsien; Hsu, Cheng-Yi; Tai, Wei-Tien; Li, Yong-Shi; Chen, I-Ting; Liu, Chun-Yu; Chen, Kuen-Feng; Shiau, Chung-Wai

    2014-01-01

    Hepatocellular carcinoma is the fifth most common solid cancer worldwide. Sorafenib, a small multikinase inhibitor, is the only approved therapy for advanced HCC. The clinical benefit of sorafenib is offset by the acquisition of sorafenib resistance. Understanding of the molecular mechanism of STAT3 overexpression in sorafenib resistance is critical if the clinical benefits of this drug are to be improved. In this study, we explored our hypothesis that loss of RFX-1/SHP-1 and further increase of p-STAT3 as a result of sorafenib treatment induces sorafenib resistance as a cytoprotective response effect, thereby, limiting sorafenib sensitivity and efficiency. We found that knockdown of RFX-1 protected HCC cells against sorafenib-induced cell apoptosis and SHP-1 activity was required for the process. SC-2001, a molecule with similar structure to obatoclax, synergistically suppressed tumor growth when used in combination with sorafenib in vitro and overcame sorafenib resistance through up-regulating RFX-1 and SHP-1 resulting in tumor suppression and mediation of dephosphorylation of STAT3. In addition, sustained sorafenib treatment in HCC led to increased p-STAT3 which was a key mediator of sorafenib sensitivity. The combination of SC-2001 and sorafenib strongly inhibited tumor growth in both wild-type and sorafenib-resistant HCC cell bearing xenograft models. These results demonstrate that inactivation of RFX/SHP-1 induced by sustained sorafenib treatment confers sorafenib resistance to HCC through p-STAT3 up-regulation. These effects can be overcome by SC-2001 through RFX-1/SHP-1 dependent p-STAT3 suppression. In conclusion, the use of SC-2001 in combination with sorafenib may constitute a new strategy for HCC therapy. PMID:25047655

  3. Stimulation of the B-cell receptor activates the JAK2/STAT3 signaling pathway in chronic lymphocytic leukemia cells

    PubMed Central

    Rozovski, Uri; Wu, Ji Yuan; Harris, David M.; Liu, Zhiming; Li, Ping; Hazan-Halevy, Inbal; Ferrajoli, Alessandra; Burger, Jan A.; O’Brien, Susan; Jain, Nitin; Verstovsek, Srdan; Wierda, William G.; Keating, Michael J.

    2014-01-01

    In chronic lymphocytic leukemia (CLL), stimulation of the B-cell receptor (BCR) triggers survival signals. Because in various cells activation of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway provides cells with survival advantage, we wondered whether BCR stimulation activates the JAK/STAT pathway in CLL cells. To stimulate the BCR we incubated CLL cells with anti-IgM antibodies. Anti-IgM antibodies induced transient tyrosine phosphorylation and nuclear localization of phosphorylated (p) STAT3. Immunoprecipitation studies revealed that anti-JAK2 antibodies coimmunoprecipitated pSTAT3 and pJAK2 in IgM-stimulated but not unstimulated CLL cells, suggesting that activation of the BCR induces activation of JAK2, which phosphorylates STAT3. Incubation of CLL cells with the JAK1/2 inhibitor ruxolitinib inhibited IgM-induced STAT3 phosphorylation and induced apoptosis of IgM-stimulated but not unstimulated CLL cells in a dose- and time-dependent manner. Whether ruxolitinib treatment would benefit patients with CLL remains to be determined. PMID:24778152

  4. Stimulation of the B-cell receptor activates the JAK2/STAT3 signaling pathway in chronic lymphocytic leukemia cells.

    PubMed

    Rozovski, Uri; Wu, Ji Yuan; Harris, David M; Liu, Zhiming; Li, Ping; Hazan-Halevy, Inbal; Ferrajoli, Alessandra; Burger, Jan A; O'Brien, Susan; Jain, Nitin; Verstovsek, Srdan; Wierda, William G; Keating, Michael J; Estrov, Zeev

    2014-06-12

    In chronic lymphocytic leukemia (CLL), stimulation of the B-cell receptor (BCR) triggers survival signals. Because in various cells activation of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway provides cells with survival advantage, we wondered whether BCR stimulation activates the JAK/STAT pathway in CLL cells. To stimulate the BCR we incubated CLL cells with anti-IgM antibodies. Anti-IgM antibodies induced transient tyrosine phosphorylation and nuclear localization of phosphorylated (p) STAT3. Immunoprecipitation studies revealed that anti-JAK2 antibodies coimmunoprecipitated pSTAT3 and pJAK2 in IgM-stimulated but not unstimulated CLL cells, suggesting that activation of the BCR induces activation of JAK2, which phosphorylates STAT3. Incubation of CLL cells with the JAK1/2 inhibitor ruxolitinib inhibited IgM-induced STAT3 phosphorylation and induced apoptosis of IgM-stimulated but not unstimulated CLL cells in a dose- and time-dependent manner. Whether ruxolitinib treatment would benefit patients with CLL remains to be determined.

  5. Leptin activates chicken growth hormone promoter without chicken STAT3 in vitro.

    PubMed

    Murase, Daisuke; Namekawa, Shoko; Ohkubo, Takeshi

    2016-01-01

    Leptin is an adipocyte-derived hormone that not only regulates food intake and energy homeostasis but also induces growth hormone (GH) mRNA expression and release, thereby controlling growth and metabolism in mammals. The molecular mechanism of leptin-induced regulation of GH gene transcription is unclear. The current study investigated the effects of leptin on the chicken GH (cGH) promoter and the molecular mechanism underlying leptin-induced cGH gene expression in vitro. Leptin activated the cGH promoter in the presence of chPit-1α in CHO cells stably expressing the chicken leptin receptor. Promoter activation did not require STAT-binding elements in the cGH promoter or STAT3 activity. However, JAK2 activation was required for leptin-dependent activity. JAK2-dependent pathways include p42/44 MAPK and PI3K, and inhibition of these pathways partially blocked leptin-induced cGH gene transcription. Although CK2 directly activates JAK2, a CK2 inhibitor blocked leptin-dependent activation of the cGH gene without affecting JAK2 phosphorylation. The CK2 inhibitor suppressed Erk1/2 and Akt phosphorylation. Additional data implicate Src family kinases in leptin-dependent cGH gene activation. These results suggest that leptin activates the cGH gene in the presence of chPit-1α via several leptin-activated kinases. Although further study is required, we suggest that the leptin-induced JAK2/p42/44 MAPK and JAK2/PI3K cascades are activated by Src-meditated CK2, leading to CBP phosphorylation and interaction with chPit-1α, resulting in transactivation of the cGH promoter.

  6. 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

  7. Interleukin-6-Specific Activation of the C/EBPδ Gene in Hepatocytes Is Mediated by Stat3 and Sp1

    PubMed Central

    Cantwell, Carrie A.; Sterneck, Esta; Johnson, Peter F.

    1998-01-01

    C/EBPδ (CCAAT/enhancer binding protein δ) has been implicated as a regulator of acute-phase response (APR) genes in hepatocytes. Its expression increases dramatically in liver during the APR and can be induced in hepatic cell lines by interleukin-6 (IL-6), an acute-phase mediator that activates transcription of many APR genes. Here we have investigated the mechanism by which C/EBPδ expression is regulated by IL-6 in hepatoma cells. C/EBPδ promoter sequences to −125 bp are sufficient for IL-6 inducibility of a reporter gene and include an APR element (APRE) that is essential for IL-6 responsiveness. DNA binding experiments and transactivation assays demonstrate that Stat3, but not Stat1, interacts with this APRE. Two Sp1 sites, one of which is adjacent to the APRE, are required for IL-6 induction and transactivation by Stat3. Thus, Stat3 and Sp1 function cooperatively to activate the C/EBPδ promoter. Replacement of the APRE with Stat binding elements (SBEs) from the ICAM-1 or C/EBPβ promoter, both of which recognize both Stat1 and Stat3, confers responsiveness to gamma interferon, a cytokine that selectively activates Stat1. Sequence comparisons suggest that the distinct Stat binding specificities of the C/EBPδ and C/EBPβ SBEs are determined primarily by a single base pair difference. Our findings indicate that the cytokine specificity of C/EBPδ gene expression is governed by the APRE sequence. PMID:9528783

  8. The Shc1 adaptor simultaneously balances Stat1 and Stat3 activity to promote breast cancer immune suppression

    PubMed Central

    Ahn, Ryuhjin; Sabourin, Valérie; Bolt, Alicia M.; Hébert, Steven; Totten, Stephanie; De Jay, Nicolas; Festa, Maria Carolina; Young, Yoon Kow; Im, Young Kyuen; Pawson, Tony; Koromilas, Antonis E.; Muller, William J.; Mann, Koren K.; Kleinman, Claudia L.; Ursini-Siegel, Josie

    2017-01-01

    Tyrosine kinase signalling within cancer cells is central to the establishment of an immunosuppressive microenvironment. Although tyrosine kinase inhibitors act, in part, to augment adaptive immunity, the increased heterogeneity and functional redundancy of the tyrosine kinome is a hurdle to achieving durable responses to immunotherapies. We previously identified the Shc1 (ShcA) scaffold, a central regulator of tyrosine kinase signalling, as essential for promoting breast cancer immune suppression. Herein we show that the ShcA pathway simultaneously activates STAT3 immunosuppressive signals and impairs STAT1-driven immune surveillance in breast cancer cells. Impaired Y239/Y240-ShcA phosphorylation selectively reduces STAT3 activation in breast tumours, profoundly sensitizing them to immune checkpoint inhibitors and tumour vaccines. Finally, the ability of diminished tyrosine kinase signalling to initiate STAT1-driven immune surveillance can be overcome by compensatory STAT3 hyperactivation in breast tumours. Our data indicate that inhibition of pY239/240-ShcA-dependent STAT3 signalling may represent an attractive therapeutic strategy to sensitize breast tumours to multiple immunotherapies. PMID:28276425

  9. The Shc1 adaptor simultaneously balances Stat1 and Stat3 activity to promote breast cancer immune suppression.

    PubMed

    Ahn, Ryuhjin; Sabourin, Valérie; Bolt, Alicia M; Hébert, Steven; Totten, Stephanie; De Jay, Nicolas; Festa, Maria Carolina; Young, Yoon Kow; Im, Young Kyuen; Pawson, Tony; Koromilas, Antonis E; Muller, William J; Mann, Koren K; Kleinman, Claudia L; Ursini-Siegel, Josie

    2017-03-09

    Tyrosine kinase signalling within cancer cells is central to the establishment of an immunosuppressive microenvironment. Although tyrosine kinase inhibitors act, in part, to augment adaptive immunity, the increased heterogeneity and functional redundancy of the tyrosine kinome is a hurdle to achieving durable responses to immunotherapies. We previously identified the Shc1 (ShcA) scaffold, a central regulator of tyrosine kinase signalling, as essential for promoting breast cancer immune suppression. Herein we show that the ShcA pathway simultaneously activates STAT3 immunosuppressive signals and impairs STAT1-driven immune surveillance in breast cancer cells. Impaired Y239/Y240-ShcA phosphorylation selectively reduces STAT3 activation in breast tumours, profoundly sensitizing them to immune checkpoint inhibitors and tumour vaccines. Finally, the ability of diminished tyrosine kinase signalling to initiate STAT1-driven immune surveillance can be overcome by compensatory STAT3 hyperactivation in breast tumours. Our data indicate that inhibition of pY239/240-ShcA-dependent STAT3 signalling may represent an attractive therapeutic strategy to sensitize breast tumours to multiple immunotherapies.

  10. 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.

  11. Highly pathogenic avian influenza H5N1 virus delays apoptotic responses via activation of STAT3.

    PubMed

    Hui, Kenrie P Y; Li, Hung Sing; Cheung, Man Chun; Chan, Renee W Y; Yuen, Kit M; Mok, Chris K P; Nicholls, John M; Peiris, J S Malik; Chan, Michael C W

    2016-06-27

    Highly pathogenic avian influenza (HPAI) H5N1 virus continues to pose pandemic threat, but there is a lack of understanding of its pathogenesis. We compared the apoptotic responses triggered by HPAI H5N1 and low pathogenic H1N1 viruses using physiologically relevant respiratory epithelial cells. We demonstrated that H5N1 viruses delayed apoptosis in primary human bronchial and alveolar epithelial cells (AECs) compared to H1N1 virus. Both caspase-8 and -9 were activated by H5N1 and H1N1 viruses in AECs, while H5N1 differentially up-regulated TRAIL. H5N1-induced apoptosis was reduced by TRAIL receptor silencing. More importantly, STAT3 knock-down increased apoptosis by H5N1 infection suggesting that H5N1 virus delays apoptosis through activation of STAT3. Taken together, we demonstrate that STAT3 is involved in H5N1-delayed apoptosis compared to H1N1. Since delay in apoptosis prolongs the duration of virus replication and production of pro-inflammatory cytokines and TRAIL from H5N1-infected cells, which contribute to orchestrate cytokine storm and tissue damage, our results suggest that STAT3 may play a previously unsuspected role in H5N1 pathogenesis.

  12. The Role of Stat3 Activation in Androgen Receptor Signaling and Prostate Cancer

    DTIC Science & Technology

    2005-07-01

    Lapidot oligonucleotides with the Stat3 siRNA identified in Z, Leeder JS, Freedman M, Cohen A, Gazit A, Levitzki A, this study in prostate cancer...3. Catlett-Falcone R, Landowski TH, Oshiro MM, Turkson J, stranded RNA directs the ATP-dependent cleavage of mRNA at Levitzki A, Savino R, Ciliberto G...Lee SO, Xiao X, Pflug B, Nelson JB, Gao AC. Levitzki A, Savino R, Ciliberto G, Moscinski L, Fernandez-Luna Stat3 enhances the growth of LNCaP human

  13. Phosphorylation status determines the opposing functions of Smad2/Smad3 as STAT3 cofactors in TH17 differentiation.

    PubMed

    Yoon, Jeong-Hwan; Sudo, Katsuko; Kuroda, Masahiko; Kato, Mitsuyasu; Lee, In-Kyu; Han, Jin Soo; Nakae, Susumu; Imamura, Takeshi; Kim, Juryun; Ju, Ji Hyeon; Kim, Dae-Kee; Matsuzaki, Koichi; Weinstein, Michael; Matsumoto, Isao; Sumida, Takayuki; Mamura, Mizuko

    2015-07-21

    Transforming growth factor-β (TGF-β) and interleukin-6 (IL-6) are the pivotal cytokines to induce IL-17-producing CD4(+) T helper cells (TH17); yet their signalling network remains largely unknown. Here we show that the highly homologous TGF-β receptor-regulated Smads (R-Smads): Smad2 and Smad3 oppositely modify STAT3-induced transcription of IL-17A and retinoic acid receptor-related orphan nuclear receptor, RORγt encoded by Rorc, by acting as a co-activator and co-repressor of STAT3, respectively. Smad2 linker phosphorylated by extracellular signal-regulated kinase (ERK) at the serine 255 residue interacts with STAT3 and p300 to transactivate, whereas carboxy-terminal unphosphorylated Smad3 interacts with STAT3 and protein inhibitor of activated STAT3 (PIAS3) to repress the Rorc and Il17a genes. Our work uncovers carboxy-terminal phosphorylation-independent noncanonical R-Smad-STAT3 signalling network in TH17 differentiation.

  14. Hepatitis C virus and its protein NS4B activate the cancer-related STAT3 pathway via the endoplasmic reticulum overload response.

    PubMed

    Kong, Lingbao; Li, Shanshan; Yu, Xilan; Fang, Xiaonan; Xu, Ahui; Huang, Mingjie; Wu, Xiaoyu; Guo, Yunli; Guo, Fenglin; Xu, Jin

    2016-08-01

    Oxidative stress induces the activation of signal transducer and activator of transcription 3 (STAT3), which plays an important role in hepatocellular carcinoma (HCC). We have previously reported that hepatitis C virus (HCV) and its protein NS4B induce the production of reactive oxygen species (ROS) via the endoplasmic reticulum overload response (EOR) in human hepatocytes. Here, we found that NS4B and HCV induce STAT3 activation and stimulate the expression of cancer-related STAT3 target genes, including VEGF, c-myc, MMP-9 and Mcl-1, by EOR in human hepatocytes. Moreover, the cancer-related STAT3 pathway activated by NS4B and HCV via EOR were found to promote human hepatocyte viability. Taken together, these findings revealed that HCV NS4B might contribute to HCC by activating the EOR-mediated cancer-related STAT3 pathway, and this could provide novel insights into HCV-induced HCC.

  15. Signal transducer and activator of transcription 3 (Stat3) regulates host defense and protects mice against herpes simplex virus-1 (HSV-1) infection.

    PubMed

    Hsia, Hung-Ching; Stopford, Charles M; Zhang, Zhigang; Damania, Blossom; Baldwin, Albert S

    2016-12-13

    Signal transducer and activator of transcription 3 (STAT3) mediates cellular responses to multiple cytokines, governs gene expression, and regulates the development and activation of immune cells. STAT3 also modulates reactivation of latent herpes simplex virus-1 (HSV-1) in ganglia. However, it is unclear how STAT3 regulates the innate immune response during the early phase of HSV-1 lytic infection. Many cell types critical for the innate immunity are derived from the myeloid lineage. Therefore, in this study, we used myeloid-specific Stat3 knockout mice to investigate the role of STAT3 in the innate immune response against HSV-1. Our results demonstrate that Stat3 knockout bone marrow-derived macrophages (BMMs) expressed decreased levels of interferon-α (IFN-α) and interferon-stimulated genes (ISGs) upon HSV-1 infection. In vivo, knockout mice were more susceptible to HSV-1, as marked by higher viral loads and more significant weight loss. Splenic expression of IFN-α and ISGs was reduced in the absence of STAT3, indicating that STAT3 is required for optimal type I interferon response to HSV-1. Expression of TNF-α and IL-12, cytokines that have been shown to limit HSV-1 replication and pathogenesis, was also significantly lower in knockout mice. Interestingly, Stat3 knockout mice failed to expand the CD8(+) conventional DC (cDC) population upon HSV-1 infection, and this was accompanied by impaired NK and CD8 T cell activation. Collectively, our data demonstrate that myeloid-specific Stat3 deletion causes defects in multiple aspects of the immune system and that STAT3 has a protective role at the early stage of systemic HSV-1 infection.

  16. 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

  17. Spinal leptin contributes to the development of morphine antinociceptive tolerance by activating the STAT3-NMDA receptor pathway in rats.

    PubMed

    Hu, Fen; Cui, Yu; Guo, Ruixian; Chen, Jingfu; Guo, Runming; Shen, Ning; Hua, Xiaoxiao; Mo, Liqiu; Feng, Jianqiang

    2014-08-01

    Leptin, an adipokine synthesized mainly by non‑neuronal tissues, has been reported to contribute to the pathogenesis of neuropathic pain. It has been hypothesized that morphine tolerance and neuropathic pain share some common pathological mechanisms. The present study was designed to examine whether spinal leptin is implicated in the development of morphine antinociceptive tolerance, and whether spinal leptin induces the activation of signal transducer and activator of transcription 3 (STAT3) signaling pathway and the NR1 subunit of N‑methyl‑D‑aspartate (NMDA) receptor, in morphine antinociceptive tolerance in rats. The results demonstrated that intrathecal (i.t.) administration of a leptin antagonist (LA) prevented the development of morphine antinociceptive tolerance in rats. Further studies revealed that the levels of the spinal leptin and the leptin receptor (Ob‑R) were time‑dependently increased following chronic morphine treatment. Mechanistic examination indicated that chronic morphine triggered activation of the STAT3 pathway and an increase in the expression of the NR1 subunit of the NMDA receptor, which was ameliorated by i.t. administration of AG490 [a Janus kinase (JAK)‑STAT inhibitor]. The increased activation of STAT3 and the NR1 subunit was markedly attenuated by i.t. treatment with LA. In addition, the spinal administration of AG490 or MK‑801 (a non‑competitive NMDA receptor inhibitor) blocked the development of morphine antinociceptive tolerance. Taken together, these results have demonstrated, for the first time, to the best of our knowledge, that spinal leptin contributes to the development of morphine antinociceptive tolerance by activating the spinal STAT3‑NMDA receptor pathway.

  18. GITRL modulates the activities of p38 MAPK and STAT3 to promote Th17 cell differentiation in autoimmune arthritis.

    PubMed

    Tang, Xinyi; Tian, Jie; Ma, Jie; Wang, Jiemin; Qi, Chen; Rui, Ke; Wang, Yungang; Xu, Huaxi; Lu, Liwei; Wang, Shengjun

    2016-02-23

    The glucocorticoid-induced TNFR family-related protein (GITR) and its ligand play a critical role in the pathogenesis of autoimmune arthritis by enhancing the Th17 cell response, but their molecular mechanisms remain largely unclear. This study aims to define the role of p38 mitogen-activated protein kinases (MAPK) and signal transducer and activator of transcription 3 (STAT3) signaling in GITRL-induced Th17 cells in autoimmune arthritis. We found that the p38 phosphorylation was enhanced by GITRL in activated CD4+T cells, and the p38 inhibitor restrained the GITRL-induced Th17 cell expansion in a dose-dependent manner. Moreover, there was decreased STAT3 activity on Tyr705 and Ser727 with the p38 inhibitor in vitro. Notably, the p38 inhibitor could prevent GITRL-treated arthritis progression and markedly decrease the Th17 cell percentages. The phosphorylation of the Tyr705 site was significantly lower in the GITRL-treated CIA mice administrated with the p38 inhibitor. A significantly higher phosphorylation of p38 was detected in RA patients and had a positive relationship with the serum level of anti-cyclic citrullinated peptide (anti-CCP) antibody. Our findings have indicated that GITRL could promote Th17 cell differentiation by p38 MAPK and STAT3 signaling in autoimmune arthritis.

  19. STAT3 and HIF1α cooperatively activate HIF1 target genes in MDA-MB-231 and RCC4 cells.

    PubMed

    Pawlus, M R; Wang, L; Hu, C-J

    2014-03-27

    Solid tumors often exhibit simultaneously inflammatory and hypoxic microenvironments. The 'signal transducer and activator of transcription-3' (STAT3)-mediated inflammatory response and the hypoxia-inducible factor (HIF)-mediated hypoxia response have been independently shown to promote tumorigenesis through the activation of HIF or STAT3 target genes and to be indicative of a poor prognosis in a variety of tumors. We report here for the first time that STAT3 is involved in the HIF1, but not HIF2-mediated hypoxic transcriptional response. We show that inhibiting STAT3 activity in MDA-MB-231 and RCC4 cells by a STAT3 inhibitor or STAT3 small interfering RNA significantly reduces the levels of HIF1, but not HIF2 target genes in spite of normal levels of hypoxia-inducible transcription factor 1α (HIF1α) and HIF2α protein. Mechanistically, STAT3 activates HIF1 target genes by binding to HIF1 target gene promoters, interacting with HIF1α protein and recruiting coactivators CREB binding protein (CBP) and p300, and RNA polymerase II (Pol II) to form enhanceosome complexes that contain HIF1α, STAT3, CBP, p300 and RNA Pol II on HIF1 target gene promoters. Functionally, the effect of STAT3 knockdown on proliferation, motility and clonogenic survival of tumor cells in vitro is phenocopied by HIF1α knockdown in hypoxic cells, whereas STAT3 knockdown in normoxic cells also reduces cell proliferation, motility and clonogenic survival. This indicates that STAT3 works with HIF1 to activate HIF1 target genes and to drive HIF1-depedent tumorigenesis under hypoxic conditions, but also has HIF-independent activity in normoxic and hypoxic cells. Identifying the role of STAT3 in the hypoxia response provides further data supporting the effectiveness of STAT3 inhibitors in solid tumor treatment owing to their usefulness in inhibiting both the STAT3 and HIF1 pro-tumorigenic signaling pathways in some cancer types.

  20. Gpr110 deficiency decelerates carcinogen-induced hepatocarcinogenesis via activation of the IL-6/STAT3 pathway

    PubMed Central

    Ma, Benting; Zhu, Junjie; Tan, Juan; Mao, Yulei; Tang, Lingyun; Shen, Chunling; Zhang, Hongxing; Kuang, Ying; Fei, Jian; Yang, Xiao; Wang, Zhugang

    2017-01-01

    Hepatocarcinogenesis is a complex process that includes pronounced necroinflammation, unregulated hepatocyte damage, subsequent extensive fibrosis, and carcinogenesis. GPR110 was an adhesion G protein-coupled receptor. Analysis of the expression pattern of Gpr110 in mice displayed that Gpr110 was expressed highly in liver, implicating the tissue compartments where Gpr110 could execute its functions, the role of Gpr110 in the physiological and pathological state of liver remains unclear. Based on a Gpr110 knockout mouse model, we evaluated the role of Gpr110 in hepatocarcinogenesis by using a carbon tetrachloride (CCl4)-induced liver injury and fibrosis model, as well as diethylnitrosamine (DEN) plus CCl4-induced liver cancer model. In this study, we found subdued chronic liver injury, reduced compensatory proliferation, lower liver fibrosis, but enhanced inflammation occurred in Gpr110-/- mice during CCl4 challenge. In addition, Gpr110-/- mice were resistant to liver tumorigenesis induced by DEN plus CCl4 injection. Molecular mechanisms underlying these differences correlated with augmented activation of the IL-6/STAT3 pathway, which exerted hepatoprotective effects during liver damage, fibrosis, and oncogenesis in Gpr110-/- mice. Furthermore, pharmacological inhibition of the activation of the IL-6/STAT3 pathway enhanced hepatic fibrosis and promoted DEN plus CCl4-induced carcinogenesis in Gpr110-/- mice. In summary, absence of Gpr110 decelerates liver fibrosis/cirrhosis progressing into tumorigenesis, due to strengthening activation of the IL-6/STAT3 pathway, leading to a weaker liver injury and fibrosis microenvironment. It is indicated that targeting Gpr110 and activating the IL-6/STAT3 pathway may be considered to be preventive methods for some cirrhosis transition.

  1. Dual inhibition of Janus and Src family kinases by novel indirubin derivative blocks constitutively-activated Stat3 signaling associated with apoptosis of human pancreatic cancer cells.

    PubMed

    Nam, Sangkil; Wen, Wei; Schroeder, Anne; Herrmann, Andreas; Yu, Hua; Cheng, Xinlai; Merz, Karl-Heinz; Eisenbrand, Gerhard; Li, Hongzhi; Yuan, Yate-Ching; Jove, Richard

    2013-06-01

    Constitutively-activated JAK/Stat3 or Src/Stat3 signaling plays a crucial role in tumor cell survival, proliferation, angiogenesis and immune suppression. Activated JAK/Stat3 or Src/Stat3 has been validated as a promising molecular target for cancer therapy. However, prolonged inhibition of Src family kinases (SFKs) leads to reactivation of signal transducer and activator of transcript 3 (Stat3) and tumor cell survival through altered JAK/Stat3 interaction. This compensatory feedback suggests that dual inhibition of Janus kinases (JAKs) and SFKs might be a promising strategy for targeting downstream Stat3 signaling in the clinic. In this study, we identify that the natural product derivative E738 is a novel dual inhibitor of JAKs and SFKs. The IC(50) values of E738 against recombinant JAKs and SFKs in vitro are in the ranges of 0.7-74.1 nM and 10.7-263.9 nM, respectively. We observed that phosphorylation of both Jak2 and Src was substantially inhibited in the submicromolar range by E738 in cultured human pancreatic tumor cells, followed by blockade of downstream Stat3 activation. E738 down-regulated expression of the Stat3 target proteins Mcl-1 and survivin, associated with induction of apoptosis. Computational models and molecular dynamics simulations of E738/Tyk2 or E738/Src in silico suggest that E738 inhibits both tyrosine kinase 2 (Tyk2) and Src as an ATP-competitive ligand. Moreover, the planar E738 molecule demonstrates a strong binding affinity in the compact ATP-binding site of Tyk2. In sum, E738 is the first dual inhibitor of JAKs and SFKs, followed by inhibition of Stat3 signaling. Thus, according to in vitro experiments, E738 is a promising new therapeutic agent for human pancreatic cancer treatment by blocking both oncogenic pathways simultaneously.

  2. Myocyte-Derived Hsp90 Modulates Collagen Upregulation via Biphasic Activation of STAT-3 in Fibroblasts during Cardiac Hypertrophy.

    PubMed

    Datta, Ritwik; Bansal, Trisha; Rana, Santanu; Datta, Kaberi; Datta Chaudhuri, Ratul; Chawla-Sarkar, Mamta; Sarkar, Sagartirtha

    2017-03-15

    Signal transducer and activator of transcription 3 (STAT-3)-mediated signaling in relation to upregulated collagen expression in fibroblasts during cardiac hypertrophy is well defined. Our recent findings have identified heat shock protein 90 (Hsp90) to be a critical modulator of fibrotic signaling in cardiac fibroblasts in this disease milieu. The present study was therefore intended to analyze the role of Hsp90 in the STAT-3-mediated collagen upregulation process. Our data revealed a significant difference between in vivo and in vitro results, pointing to a possible involvement of myocyte-fibroblast cross talk in this process. Cardiomyocyte-targeted knockdown of Hsp90 in rats (Rattus norvegicus) in which the renal artery was ligated showed downregulated collagen synthesis. Furthermore, the results obtained with cardiac fibroblasts conditioned with Hsp90-inhibited hypertrophied myocyte supernatant pointed toward cardiomyocytes' role in the regulation of collagen expression in fibroblasts during hypertrophy. Our study also revealed a novel signaling mechanism where myocyte-derived Hsp90 orchestrates not only p65-mediated interleukin-6 (IL-6) synthesis but also its release in exosomal vesicles. Such myocyte-derived exosomes and myocyte-secreted IL-6 are responsible in unison for the biphasic activation of STAT-3 signaling in cardiac fibroblasts that culminates in excess collagen synthesis, leading to severely compromised cardiac function during cardiac hypertrophy.

  3. NANOG regulates epithelial-mesenchymal transition and chemoresistance through activation of the STAT3 pathway in epithelial ovarian cancer.

    PubMed

    Liu, Suqing; Sun, Jing; Cai, Bin; Xi, Xiaowei; Yang, Liu; Zhang, Zhenbo; Feng, Youji; Sun, Yunyan

    2016-07-01

    NANOG is a key transcription factor that is overexpressed and plays an important role in various cancers. Its overexpression is associated with highly tumorigenic, drug-resistant, and poor prognosis. However, the underlying mechanism of action of NANOG in ovarian cancer remains unclear. Epithelial-mesenchymal transition (EMT), which is a critical process in cancer invasion and metastasis, is also associated with drug resistance. We determined whether NANOG is associated with EMT and chemoresistance in epithelial ovarian cancer cells. NANOG expression was increased in epithelial ovarian cancer cells (HEY and SKOV3) compared with normal epithelial ovarian cells (Moody). Low expression of NANOG increased the expression of E-cadherin and decreased the expression of vimentin, β-catenin, and Snail. Furthermore, the cell migration and invasion abilities were decreased. The multidrug resistance genes MDR-1 and GST-π were also downregulated when NANOG was lowly expressed. The cells that were transfected with the si-NANOG plasmid were more sensitive to cisplatin compared with the cells that were transfected with empty vector. The data demonstrated that Stat3 was correlated with NANOG-mediated EMT and drug resistance. The silencing of Stat3 expression abrogated NANOG-mediated EMT changes and increased the sensitivity of the cells to chemotherapy. These results suggest that NANOG mediates EMT and drug resistance through activation of the Stat3 pathway in epithelial ovarian cancer.

  4. Phosphorylated heat shock protein 27 promotes lipid clearance in hepatic cells through interacting with STAT3 and activating autophagy.

    PubMed

    Shen, Lei; Qi, Zhilin; Zhu, Yanyan; Song, Xiaomeng; Xuan, Chunxia; Ben, Peiling; Lan, Lei; Luo, Lan; Yin, Zhimin

    2016-08-01

    Nonalcoholic fatty liver disease (NAFLD) has become the major liver disease worldwide. Recently, several studies have identified that the activation of autophagy attenuates hepatic steatosis. Heat shock protein 27 (Hsp27) is involved in autophagy in response to various stimuli. In this study, we demonstrate that phosphorylated Hsp27 stimulates autophagy and lipid droplet clearance and interacts with STAT3. In vivo study showed that high fat diet (HFD) feeding increased Hsp25 (mouse orthology of Hsp27) phosphorylation and autophagy in mouse livers. Inhibition of Hsp25 phosphorylation exacerbated HFD-induced hepatic steatosis in mice. In vitro study showed that palmitate-induced lipid overload in hepatic cells was enhanced by Hsp27 knockdown, KRIBB3 treatment and Hsp27-3A (non-phosphorylatable) overexpression but was prevented by Hsp27-WT (wild type) and Hsp27-3D (phosphomimetic) overexpression. Mechanism analysis demonstrated that palmitate could induce Hsp27 phosphorylation which promoted palmitate-induced autophagy. Phosphorylated Hsp27 interacted with STAT3 in response to palmitate treatment, and disrupted the STAT3/PKR complexes, facilitated PKR-dependent eIF2α phosphorylation, and thus stimulated autophagy. To conclude, our study provides a novel mechanism by which the phosphorylated Hsp27 promotes hepatic lipid clearance and suggests a new insight for therapy of steatotic diseases such as nonalcoholic fatty liver disease (NAFLD).

  5. Early Secreted Antigenic Target of 6-kDa of Mycobacterium tuberculosis Stimulates IL-6 Production by Macrophages through Activation of STAT3

    PubMed Central

    Jung, Bock-Gie; Wang, Xisheng; Yi, Na; Ma, Justin; Turner, Joanne; Samten, Buka

    2017-01-01

    As early secreted antigenic target of 6 kDa (ESAT-6) of Mycobacterium tuberculosis (Mtb) is an essential virulence factor and macrophages are critical for tuberculosis infection and immunity, we studied ESAT-6 stimulated IL-6 production by macrophages. ESAT-6 stimulated significantly higher IL-6 secretion by murine bone marrow derived macrophages (BMDM) compared to culture filtrate protein 10 kDa (CFP10) and antigen 85A. Polymyxin B, an LPS blocker, did not affect ESAT-6 stimulated macrophage IL-6 production. ESAT-6 but not Pam3CSK4 induced IL-6 by TLR2 knockout BMDM. ESAT-6 induced phosphorylation and DNA binding of STAT3 and this was blocked by STAT3 inhibitors but not by rapamycin. STAT3 inhibitors suppressed ESAT-6-induced IL-6 transcription and secretion without affecting cell viability. This was confirmed by silencing STAT3 in macrophages. Blocking neither IL-6Rα/IL-6 nor IL-10 affected ESAT-6-induced STAT3 activation and IL-6 production. Infection of BMDM and human macrophages with Mtb with esat-6 deletion induced diminished STAT3 activation and reduced IL-6 production compared to wild type and esat-6 complemented Mtb strains. Administration of ESAT-6 but not CFP10 induced STAT3 phosphorylation and IL-6 expression in the mouse lungs, consistent with expression of ESAT-6, IL-6 and phosphorylated-STAT3 in Mtb-infected mouse lungs. We conclude that ESAT-6 stimulates macrophage IL-6 production through STAT3 activation. PMID:28106119

  6. Sphingosine-1-phosphate enhances satellite cell activation in dystrophic muscles through a S1PR2/STAT3 signaling pathway.

    PubMed

    Loh, Kenneth C; Leong, Weng-In; Carlson, Morgan E; Oskouian, Babak; Kumar, Ashok; Fyrst, Henrik; Zhang, Meng; Proia, Richard L; Hoffman, Eric P; Saba, Julie D

    2012-01-01

    Sphingosine-1-phosphate (S1P) activates a widely expressed family of G protein-coupled receptors, serves as a muscle trophic factor and activates muscle stem cells called satellite cells (SCs) through unknown mechanisms. Here we show that muscle injury induces dynamic changes in S1P signaling and metabolism in vivo. These changes include early and profound induction of the gene encoding the S1P biosynthetic enzyme SphK1, followed by induction of the catabolic enzyme sphingosine phosphate lyase (SPL) 3 days later. These changes correlate with a transient increase in circulating S1P levels after muscle injury. We show a specific requirement for SphK1 to support efficient muscle regeneration and SC proliferation and differentiation. Mdx mice, which serve as a model for muscular dystrophy (MD), were found to be S1P-deficient and exhibited muscle SPL upregulation, suggesting that S1P catabolism is enhanced in dystrophic muscle. Pharmacological SPL inhibition increased muscle S1P levels, improved mdx muscle regeneration and enhanced SC proliferation via S1P receptor 2 (S1PR2)-dependent inhibition of Rac1, thereby activating Signal Transducer and Activator of Transcription 3 (STAT3), a central player in inflammatory signaling. STAT3 activation resulted in p21 and p27 downregulation in a S1PR2-dependent fashion in myoblasts. Our findings suggest that S1P promotes SC progression through the cell cycle by repression of cell cycle inhibitors via S1PR2/STAT3-dependent signaling and that SPL inhibition may provide a therapeutic strategy for MD.

  7. Gemcitabine enhances cell invasion via activating HAb18G/CD147-EGFR-pSTAT3 signaling

    PubMed Central

    Wu, Xiao-Qing; Wu, Bo; Xu, Liang; Jiang, Jian-Li; Li, Ling; Chen, Zhi-Nan

    2016-01-01

    Pancreatic cancer, one of the most lethal cancers, has very poor 5-year survival partly due to gemcitabine resistance. Recently, it was reported that chemotherapeutic agents may act as stressors to induce adaptive responses and to promote chemoresistance in cancer cells. During long-term drug treatment, the minority of cancer cells survive and acquire an epithelial-mesenchymal transition phenotype with increased chemo-resistance and metastasis. However, the short-term response of most cancer cells remains unclear. This study aimed to investigate the short-term response of pancreatic cancer cells to gemcitabine stress and to explore the corresponding mechanism. Our results showed that gemcitabine treatment for 24 hours enhanced pancreatic cancer cell invasion. In gemcitabine-treated cells, HAb18G/CD147 was up-regulated; and HAb18G/CD147 down-regulation or inhibition attenuated gemcitabine-enhanced invasion. Mechanistically, HAb18G/CD147 promoted gemcitabine-enhanced invasion by activating the EGFR (epidermal growth factor receptor)-STAT3 (signal transducer and activator of transcription 3) signaling pathway. Inhibition of EGFR-STAT3 signaling counteracted gemcitabine-enhanced invasion, and which relied on HAb18G/CD147 levels. In pancreatic cancer tissues, EGFR was highly expressed and positively correlated with HAb18G/CD147. These data indicate that pancreatic cancer cells enhance cell invasion via activating HAb18G/CD147-EGFR-pSTAT3 signaling. Our findings suggest that inhibiting HAb18G/CD147 is a potential strategy for overcoming drug stress-associated resistance in pancreatic cancer. PMID:27556697

  8. Glucagon-like peptide-1 (GLP-1) induces M2 polarization of human macrophages via STAT3 activation.

    PubMed

    Shiraishi, Daisuke; Fujiwara, Yukio; Komohara, Yoshihiro; Mizuta, Hiroshi; Takeya, Motohiro

    2012-08-24

    It is known that glucagon-like peptide-1 (GLP-1) is a hormone secreted postprandially from the L-cells of the small intestine and regulates glucose homeostasis. GLP-1 is now used for the treatment of diabetes because of its beneficial role against insulin resistance. The GLP-1 receptor (GLP-1R) is expressed on many cell types, including macrophages, and GLP-1 suppresses the development of atherosclerosis by inhibiting macrophage function. However, there have so far been few studies that have investigated the significance of GLP-1/GLP-1R signaling in macrophage activation. In the present study, we examined the effect of GLP-1 and exenatide, a GLP-1R agonist, on human monocyte-derived macrophage (HMDM) activation. We found that GLP-1 induced signal transducer and activator of transcription 3 (STAT3) activation. Silencing of GLP-1R suppressed the GLP-1-induced STAT3 activation. In addition, alternatively activated (M2) macrophage-related molecules, such as IL-10, CD163, and CD204 in HMDM, were significantly upregulated by GLP-1. Furthermore, the co-culture of 3T3-L1 adipocytes with GLP-1-treated RAW 264.7 macrophages increased the secretion of adiponectin compared to co-culture of the 3T3-L1 adipocytes with untreated RAW 264.7 macrophages. Our results demonstrate that GLP-1 induces macrophage polarization toward the M2 phenotype, which may contribute to the protective effects of GLP-1 against diabetes and cardiovascular diseases.

  9. Andrographolide causes apoptosis via inactivation of STAT3 and Akt and potentiates antitumor activity of gemcitabine in pancreatic cancer.

    PubMed

    Bao, Guo-Qing; Shen, Bai-Yong; Pan, Chun-Peng; Zhang, Ya-Jing; Shi, Min-Min; Peng, Cheng-Hong

    2013-09-12

    Gemcitabine is a first-line drug utilised in the chemotherapy of pancreatic cancer; however, this drug induces chemo-resistance and toxicity to normal tissue during treatment. Here, we firstly report that andrographolide (ANDRO) alone not only has anti-pancreatic cancer activity, but it also potentiates the anti-tumour activity of gemcitabine. Treatment with ANDRO alone inhibits proliferation of the pancreatic cancer cell lines in a dose- and time-dependent manner in vitro. Interestingly, ANDRO induces cell cycle arrest and apoptosis of pancreatic cancer cells by inhibiting STAT3 and Akt activation, upregulating the expression of p21(WAF1) and Bax, and downregulating the expression of cyclinD1, cyclinE, survivin, X-IAP and Bcl-2. Additionally, ANDRO combined with gemcitabine significantly induce stronger cell cycle arrest and more obvious apoptosis than each single treatment. The mechanistic study demonstrates that this synergistic effect is also dependent on the inhibition of STAT3 and Akt activations which subsequently regulates the pathways involved in the apoptosis and cell cycle arrest. Furthermore, both ANDRO alone and the combination treatments exhibit efficacious anti-tumour activity in vivo. Overall, our results provide solid evidence supporting that ANDRO alone or its combination with gemcitabine is a potential chemotherapeutic approach for treating human pancreatic cancer in clinical practice.

  10. Physalin A exerts anti-tumor activity in non-small cell lung cancer cell lines by suppressing JAK/STAT3 signaling

    PubMed Central

    Loo, Jacky F.C.; Xia, Dajin; Gao, Sizhi P.; Ma, Zhongjun; Chen, Zhe

    2016-01-01

    The signal transducers and activators of transcription 3 (STAT3) signaling pathway plays critical roles in the pathogenesis and progression of various human cancers, including non-small cell lung cancer (NSCLC). In this study, we aimed to evaluate the therapeutic potential of physalin A, a bioactive withanolide derived from Physalis alkekengi var. francheti used in traditional Chinese medicine, was evaluated in human NSCLC cells. Its and determined whether it effect oninhibited both constitutive and induced STAT3 activity, through repressing the phosphorylation levels of JAK2 and JAK3, resulting in anti-proliferation and pro-apoptotic effects on NSCLC cells was also determined, and. theThe antitumor effects of physalin A were also validated usingin an in vivo mouse xenograft models of NSCLC cells. Physalin A had anti-proliferative and pro-apoptotic effects in NSCLC cells with constitutively activated STAT3; it also suppressed both constitutive and induced STAT3 activity by modulating the phosphorylation of JAK2 and JAK3. Furthermore, physalin A abrogated the nuclear translocation and transcriptional activity of STAT3, thereby decreasing the expression levels of STAT3, its target genes, such as Bcl-2 and XIAP. Knockdown of STAT3 expression by small interfering RNA (siRNA) significantly enhanced the pro-apoptotic effects of physalin A in NSCLC cells. Moreover, physalin A significantly suppressed tumor xenograft growth. Thus, as an inhibitor of JAK2/3-STAT3 signaling, physalin A, has potent anti-tumor activities, which may facilitate the development of a therapeutic strategy for treating NSCLC. PMID:26843613

  11. High Glucose-Mediated STAT3 Activation in Endometrial Cancer Is Inhibited by Metformin: Therapeutic Implications for Endometrial Cancer

    PubMed Central

    Wallbillich, John J.; Josyula, Srirama; Saini, Uksha; Zingarelli, Roman A.; Dorayappan, Kalpana Deepa Priya; Riley, Maria K.; Wanner, Ross A.; Cohn, David E.; Selvendiran, Karuppaiyah

    2017-01-01

    Objectives STAT3 is over-expressed in endometrial cancer, and diabetes is a risk factor for the development of type 1 endometrial cancer. We therefore investigated whether glucose concentrations influence STAT3 expression in type 1 endometrial cancer, and whether such STAT3 expression might be inhibited by metformin. Methods In Ishikawa (grade 1) endometrial cancer cells subjected to media with low, normal, or high concentrations of glucose, expression of STAT3 and its target proteins was evaluated by real-time quantitative PCR (qPCR). Ishikawa cells were treated with metformin and assessed with cell proliferation, survival, migration, and ubiquitin assays, as well as Western blot and qPCR. Expression of apoptosis proteins was evaluated with Western blot in Ishikawa cells transfected with a STAT3 overexpression plasmid and treated with metformin. A xenograft tumor model was used for studying the in vivo efficacy of metformin. Results Expression of STAT3 and its target proteins was increased in Ishikawa cells cultured in high glucose media. In vitro, metformin inhibited cell proliferation, survival and migration but induced apoptosis. Metformin reduced expression levels of pSTAT3 ser727, total STAT3, and its associated cell survival and anti-apoptotic proteins. Additionally, metformin treatment was associated with increased degradation of pSTAT3 ser727. No change in apoptotic protein expression was noticed with STAT3 overexpression in Ishikawa cells. In vivo, metformin treatment led to a decrease in tumor weight as well as reductions of STAT3, pSTAT3 ser727, its target proteins. Conclusions These results suggest that STAT3 expression in type 1 endometrial cancer is stimulated by a high glucose environment and inhibited by metformin. PMID:28114390

  12. Gp130-mediated STAT3 activation by S-propargyl-cysteine, an endogenous hydrogen sulfide initiator, prevents doxorubicin-induced cardiotoxicity

    PubMed Central

    Wu, J; Guo, W; Lin, S-Z; Wang, Z-J; Kan, J-T; Chen, S-Y; Zhu, Y-Z

    2016-01-01

    Doxorubicin (Dox) could trigger a large amount of apoptotic cells in the myocardium, which leads to dilated cardiomyopathy and heart failure. S-propargyl-cysteine (SPRC), a producing agent of endogenous hydrogen sulfide (H2S), possesses cardioprotective efficacy. However, the specific effect and mechanism of SPRC in Dox-induced cardiotoxicity remain elusive. Given gp130 with its main downstream signaling molecule, signal transducer and activator of transcription 3 (STAT3), is involved in cardiac myocyte survival and growth; the present study was performed to elucidate whether SPRC counteracts Dox-induced cardiotoxicity, and if so, whether the gp130/STAT3 pathway is involved in this cardioprotective activity. SPRC stimulated the activation of STAT3 via gp130-mediated transduction tunnel in vitro and in vivo. In Dox-stimulated cardiotoxicity, SPRC enhanced cell viability, restored expression of gp130/STAT3-regulated downstream genes, inhibited apoptosis and oxidative stress, and antagonized mitochondrial dysfunction and intracellular Ca2+ overload. Intriguingly, blockade of gp130/STAT3 signaling abrogated all these beneficial capacities of SPRC. Our findings present the first piece of evidence for the therapeutic properties of SPRC in alleviating Dox cardiotoxicity, which could be attributed to the activation of gp130-mediated STAT3 signaling. This will offer a novel molecular basis and therapeutic strategy of H2S donor for the treatment of heart failure. PMID:27537522

  13. 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-β 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

  14. HCS Campaign to Identify Selective Inhibitors of IL-6-Induced STAT3 Pathway Activation in Head and Neck Cancer Cell Lines

    PubMed Central

    Sen, Malabika; Hua, Yun; Camarco, Daniel P.; Shun, Tong Ying; Lazo, John S.; Wilson, Gabriela Mustata; Resnick, Lynn O.; LaPorte, Matthew G.; Wipf, Peter; Huryn, Donna M.; Grandis, Jennifer R.

    2015-01-01

    Abstract Signal transducer and activator of transcription factor 3 (STAT3) is hyperactivated in head and neck squamous cell carcinomas (HNSCC). Cumulative evidence indicates that IL-6 production by HNSCC cells and/or stromal cells in the tumor microenvironment activates STAT3 and contributes to tumor progression and drug resistance. A library of 94,491 compounds from the Molecular Library Screening Center Network (MLSCN) was screened for the ability to inhibit interleukin-6 (IL-6)-induced pSTAT3 activation. For contractual reasons, the primary high-content screening (HCS) campaign was conducted over several months in 3 distinct phases; 1,068 (1.1%) primary HCS actives remained after cytotoxic or fluorescent outliers were eliminated. One thousand one hundred eighty-seven compounds were cherry-picked for confirmation; actives identified in the primary HCS and compounds selected by a structural similarity search of the remaining MLSCN library using hits identified in phases I and II of the screen. Actives were confirmed in pSTAT3 IC50 assays, and an IFNγ-induced pSTAT1 activation assay was used to prioritize selective inhibitors of STAT3 activation that would not inhibit STAT1 tumor suppressor functions. Two hundred three concentration-dependent inhibitors of IL-6-induced pSTAT3 activation were identified and 89 of these also produced IC50s against IFN-γ-induced pSTAT1 activation. Forty-nine compounds met our hit criteria: they reproducibly inhibited IL-6-induced pSTAT3 activation by ≥70% at 20 μM; their pSTAT3 activation IC50s were ≤25 μM; they were ≥2-fold selective for pSTAT3 inhibition over pSTAT1 inhibition; a cross target query of PubChem indicated that they were not biologically promiscuous; and they were ≥90% pure. Twenty-six chemically tractable hits that passed filters for nuisance compounds and had acceptable drug-like and ADME-Tox properties by computational evaluation were purchased for characterization. The hit structures were distributed

  15. NOX1 is responsible for cell death through STAT3 activation in hyperoxia and is associated with the pathogenesis of Acute Respiratory Distress Syndrome

    PubMed Central

    Carnesecchi, Stephanie; Dunand-Sauthier, Isabelle; Zanetti, Filippo; Singovski, Grigory; Deffert, Christine; Donati, Yves; Cagarelli, Thomas; Pache, Jean-Claude; Krause, Karl-Heinz; Reith, Walter; Barazzone-Argiroffo, Constance

    2014-01-01

    Reactive oxygen species (ROS) contribute to alveolar cell death in Acute Respiratory Distress Syndrome (ARDS) and we previously demonstrated that NOX1-derived ROS contributed to hyperoxia-induced alveolar cell death in mice. The study investigates whether NOX1 expression is modulated in epithelial cells concomitantly to cell death and associated to STAT3 signaling in the exudative phase of ARDS. In addition, the role of STAT3 activation in NOX1-dependent epithelial cell death was confirmed by using a lung epithelial cell line and in mice exposed to hyperoxia. NOX1 expression, cell death and STAT3 staining were evaluated in the lungs of control and ARDS patients by immunohistochemistry. In parallel, a stable NOX1-silenced murine epithelial cell line (MLE12) and NOX1-deficient mice were used to characterize signalling pathways. In the present study, we show that NOX1 is detected in alveolar epithelial cells of ARDS patients in the exudative stage. In addition, increased alveolar epithelial cell death and phosphorylated STAT3 are observed in ARDS patients and associated with NOX1 expression. Phosphorylated STAT3 is also correlated with TUNEL staining. We also confirmed that NOX1-dependent STAT3 activation participates to alveolar epithelial cell death. Silencing and acute inhibition of NOX1 in MLE12 led to decreased cell death and cleaved-caspase 3 induced by hyperoxia. Additionally, hyperoxia-induced STAT3 phosphorylation is dependent on NOX1 expression and associated with cell death in MLE12 and mice. This study demonstrates that NOX1 is involved in human ARDS pathophysiology and is responsible for the damage occurring in alveolar epithelial cells at least in part via STAT3 signalling pathways. PMID:24551274

  16. New insights into the Shwachman-Diamond Syndrome-related haematological disorder: hyper-activation of mTOR and STAT3 in leukocytes

    PubMed Central

    Bezzerri, Valentino; Vella, Antonio; Calcaterra, Elisa; Finotti, Alessia; Gasparello, Jessica; Gambari, Roberto; Assael, Baroukh Maurice; Cipolli, Marco; Sorio, Claudio

    2016-01-01

    Shwachman-Diamond syndrome (SDS) is an inherited disease caused by mutations of a gene encoding for SBDS protein. So far little is known about SBDS exact function. SDS patients present several hematological disorders, including neutropenia and myelodysplastic syndrome (MDS), with increased risk of leukemic evolution. So far, the molecular mechanisms that underlie neutropenia, MDS and AML in SDS patients have been poorly investigated. STAT3 is a key regulator of several cellular processes including survival, differentiation and malignant transformation. Moreover, STAT3 has been reported to regulate neutrophil granulogenesis and to induce several kinds of leukemia and lymphoma. STAT3 activation is known to be regulated by mTOR, which in turn plays an important role in cellular growth and tumorigenesis. Here we show for the first time, to the best of our knowledge, that both EBV-immortalized B cells and primary leukocytes obtained from SDS patients present a constitutive hyper-activation of mTOR and STAT3 pathways. Interestingly, loss of SBDS expression is associated with this process. Importantly, rapamycin, a well-known mTOR inhibitor, is able to reduce STAT3 phosphorylation to basal levels in our experimental model. A novel therapeutic hypothesis targeting mTOR/STAT3 should represent a significant step forward into the SDS clinical practice. PMID:27658964

  17. Identification of Canonical Tyrosine-dependent and Non-canonical Tyrosine-independent STAT3 Activation Sites in the Intracellular Domain of the Interleukin 23 Receptor*

    PubMed Central

    Floss, Doreen M.; Mrotzek, Simone; Klöcker, Tobias; Schröder, Jutta; Grötzinger, Joachim; Rose-John, Stefan; Scheller, Jürgen

    2013-01-01

    Signaling of interleukin 23 (IL-23) via the IL-23 receptor (IL-23R) and the shared IL-12 receptor β1 (IL-12Rβ1) controls innate and adaptive immune responses and is involved in the differentiation and expansion of IL-17-producing CD4+ T helper (TH17) cells. Activation of signal transducer and activator of transcription 3 (STAT3) appears to be the major signaling pathway of IL-23, and STAT binding sites were predicted in the IL-23R but not in the IL-12Rβ1 chain. Using site-directed mutagenesis and deletion variants of the murine and human IL-23R, we showed that the predicted STAT binding sites (pYXXQ; including Tyr-504 and Tyr-626 in murine IL-23R and Tyr-484 and Tyr-611 in human IL-23R) mediated STAT3 activation. Furthermore, we identified two uncommon STAT3 binding/activation sites within the murine IL-23R. First, the murine IL-23R carried the Y542PNFQ sequence, which acts as an unusual Src homology 2 (SH2) domain-binding protein activation site of STAT3. Second, we identified a non-canonical, phosphotyrosine-independent STAT3 activation motif within the IL-23R. A third predicted site, Tyr-416 in murine and Tyr-397 in human IL-23R, is involved in the activation of PI3K/Akt and the MAPK pathway leading to STAT3-independent proliferation of Ba/F3 cells upon stimulation with IL-23. In contrast to IL-6-induced short term STAT3 phosphorylation, cellular activation by IL-23 resulted in a slower but long term STAT3 phosphorylation, indicating that the IL-23R might not be a major target of negative feedback inhibition by suppressor of cytokine signaling (SOCS) proteins. In summary, we characterized IL-23-dependent signal transduction with a focus on STAT3 phosphorylation and identified canonical tyrosine-dependent and non-canonical tyrosine-independent STAT3 activation sites in the IL-23R. PMID:23673666

  18. 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.

  19. Scutellaria barbata D. Don inhibits growth and induces apoptosis by suppressing IL-6-inducible STAT3 pathway activation in human colorectal cancer cells

    PubMed Central

    JIANG, QIQIN; LI, QIONGYU; CHEN, HONGWEI; SHEN, ALING; CAI, QIAOYAN; LIN, JIUMAO; PENG, JUN

    2015-01-01

    One of the most critical cellular signal transduction pathways known to malfunction in colorectal cancer is the interleukin-6/signal transducer and activator of transcription 3 (IL-6/STAT3) pathway. Scutellaria barbata D. Don (SB) is well-known traditional medicine in China that targets STAT3 signaling, and it has long been used to treat various types of cancer; however, the precise mechanism of its antitumor activity remains largely unclear. In order to further elucidate this underlying mechanism, an ethanol extract of SB (EESB) in cancer treatment. The aim of the present study was to evaluate the effects of EESB on the IL-6-inducible STAT3 pathway. We tested the dose-response association between EESB, IL-6-induced proliferaion and apoptosis using an MTT assay, colony formation and flow cytometry analysis in vitro. In addition, caspase-9 and caspase-3 activation was determined using a colorimetric assay, the activity of IL-6-induced STAT3 pathway was evaluated using western blot analysis, and the expression levels of cyclin D1, cyclin-dependent kinase 4, Bcl2 and Bcl2-associated X were determined using reverse transcription-polymerase chain reaction and western blot analysis. In the present study it was found that EESB could significantly inhibit the IL-6-mediated increase in STAT3 phosphorylation levels and transcriptional activity in HT-29 human colon carcinoma cells, resulting in the suppression of cell proliferation and the induction of apoptosis. In addition, treatment with EESB markedly inhibited the IL-6-induced upregulation of cyclin D1 and B-cell lymphoma-2, two key target genes of the STAT3 pathway. These results suggest that treatment with EESB could effectively inhibit the proliferation and promote the apoptosis of human colon carcinoma cells via modulation of the IL-6/STAT3 signaling pathway and its target genes. PMID:26622533

  20. Alternative Splicing of STAT3 Is Affected by RNA Editing.

    PubMed

    Goldberg, Lior; Abutbul-Amitai, Mor; Paret, Gideon; Nevo-Caspi, Yael

    2017-03-09

    A-to-I RNA editing, carried out by adenosine deaminase acting on RNA (ADAR) enzymes, is an epigenetic phenomenon of posttranscriptional modifications on pre-mRNA. RNA editing in intronic sequences may influence alternative splicing of flanking exons. We have previously shown that conditions that induce editing result in elevated expression of signal transducer and activator of transcription 3 (STAT3), preferentially the alternatively-spliced STAT3β isoform. Mechanisms regulating alternative splicing of STAT3 have not been elucidated. STAT3 undergoes A-to-I RNA editing in an intron residing in proximity to the alternatively spliced exon. We hypothesized that RNA editing plays a role in regulating alternative splicing toward STAT3β. In this study we extend our observation connecting RNA editing to the preferential induction of STAT3β expression. We study the involvement of ADAR1 in STAT3 editing and reveal the connection between editing and alternative splicing of STAT3. Deferoaxamine treatment caused the induction in STAT3 RNA editing and STAT3β expression. Silencing ADAR1 caused a decrease in STAT3 editing and expression with a preferential decrease in STAT3β. Cells transfected with a mutated minigene showed preferential splicing toward the STAT3β transcript. Editing in the STAT3 intron is performed by ADAR1 and affects STAT3 alternative splicing. These results suggest that RNA editing is one of the molecular mechanisms regulating the expression of STAT3β.

  1. The autophagy molecule Beclin 1 maintains persistent activity of NF-κB and Stat3 in HTLV-1-transformed T lymphocytes.

    PubMed

    Chen, Li; Liu, Dan; Zhang, Yang; Zhang, Huan; Cheng, Hua

    2015-10-02

    The retroviral oncoprotein Tax from human T cell leukemia virus type 1 (HTLV-1) induces persistent activation of IκB kinase (IKK)/NF-κB signaling, an essential step for initiating HTLV-1 oncogenesis. The regulation of the IKK/NF-κB signaling in HTLV-1-transformed T cells remains incompletely understood. In the present study, we showed that the autophagy molecule Beclin1 not only executed a cytoprotective function through induction of autophagy but also played a pivotal role in maintaining Tax-induced activation of two key survival factors, NF-κB and Stat3. Silencing Beclin1 in HTLV-1-transformed T cells resulted in diminished activities of NF-κB and Stat3 as well as impaired growth. In Beclin1-depleted cells, Tax failed to activate NF-κB and Stat3 at its full capacity. In addition, we showed that Beclin1 interacted with the catalytic subunits of IKK. Further, we observed that selective inhibition of IKK repressed the activities of both NF-κB and Stat3 in the context of HTLV-1-transformation of T cells. Our data, therefore, unveiled a key role of Beclin1 in maintaining persistent activities of both NF-κB and Stat3 in the pathogenesis of HTLV-1-mediated oncogenesis.

  2. The Autophagy Molecule Beclin 1 Maintains Persistent Activity of NF-κB and Stat3 in HTLV-1-transformed T Lymphocytes

    PubMed Central

    Chen, Li; Liu, Dan; Zhang, Yang; Zhang, Huan; Cheng, Hua

    2015-01-01

    The retroviral oncoprotein Tax from human T cell leukemia virus type 1 (HTLV-1) induces persistent activation of IκB kinase (IKK)/NF-κB signaling, an essential step for initiating HTLV-1 oncogenesis. The regulation of the IKK/NF-κB signaling in HTLV-1-transformed T cells remains incompletely understood. In the present study, we showed that the autophagy molecule Beclin1 not only executed a cytoprotective function through induction of autophagy but also played a pivotal role in maintaining Tax-induced activation of two key survival factors, NF-κB and Stat3. Silencing Beclin1 in HTLV-1-transformed T cells resulted in diminished activities of NF-κB and Stat3 as well as impaired growth. In Beclin1-depleted cells, Tax failed to activate NF-κB and Stat3 at its full capacity. In addition, we showed that Beclin1 interacted with the catalytic subunits of IKK. Further, we observed that selective inhibition of IKK repressed the activities of both NF-κB and Stat3 in the context of HTLV-1-transformation of T cells. Our data, therefore, unveiled a key role of Beclin1 in maintaining persistent activities of both NF-κB and Stat3 in the pathogenesis of HTLV-1-mediated oncogenesis. PMID:26319552

  3. The stem cell adjuvant with Exendin-4 repairs the heart after myocardial infarction via STAT3 activation

    PubMed Central

    Liu, Jianfeng; Wang, Haibin; Wang, Yan; Yin, Yujing; Du, Zhiyan; Liu, Zhiqiang; Yang, Junjie; Hu, Shunying; Wang, Changyong; Chen, Yundai

    2014-01-01

    The poor survival of cells in ischaemic myocardium is a major obstacle for stem cell therapy. Exendin-4 holds the potential of cardioprotective effect based on its pleiotropic activity. This study investigated whether Exendin-4 in conjunction with adipose-derived stem cells (ADSCs) could improve the stem cell survival and contribute to myocardial repairs after infarction. Myocardial infarction (MI) was induced by the left anterior descending artery ligation in adult male Sprague-Dawley rats. ADSCs carrying double-fusion reporter gene [firefly luciferase and monomeric red fluorescent protein (fluc-mRFP)] were quickly injected into border zone of MI in rats treated with or without Exendin-4. Exendin-4 enhanced the survival of transplanted ADSCs, as demonstrated by the longitudinal in vivo bioluminescence imaging. Moreover, ADSCs adjuvant with Exendin-4 decreased oxidative stress, apoptosis and fibrosis. They also improved myocardial viability and cardiac function and increased the differentiation rates of ADSCs into cardiomyocytes and vascular smooth muscle cells in vivo. Then, ADSCs were exposed to hydrogen peroxide/serum deprivation (H2O2/SD) to mimic the ischaemic environment in vitro. Results showed that Exendin-4 decreased the apoptosis and enhanced the paracrine effect of ADSCs. In addition, Exendin-4 activated signal transducers and activators of transcription 3 (STAT3) through the phosphorylation of Akt and ERK1/2. Furthermore, Exendin-4 increased the anti-apoptotic protein Bcl-2, but decreased the pro-apoptotic protein Bax of ADSCs. In conclusion, Exendin-4 could improve the survival and therapeutic efficacy of transplanted ADSCs through STAT3 activation via the phosphorylation of Akt and ERK1/2. This study suggests the potential application of Exendin-4 for stem cell–based heart regeneration. PMID:24779911

  4. Acquisition of resistance to trastuzumab in gastric cancer cells is associated with activation of IL-6/STAT3/Jagged-1/Notch positive feedback loop.

    PubMed

    Yang, Zhengyan; Guo, Liang; Liu, Dan; Sun, Limin; Chen, Hongyu; Deng, Que; Liu, Yanjun; Yu, Ming; Ma, Yuanfang; Guo, Ning; Shi, Ming

    2015-03-10

    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.

  5. Selenate Enhances STAT3 Transcriptional Activity in Endothelial Cells: Differential Actions of Selenate and Selenite on LIF Cytokine Signaling and Cell Viability

    PubMed Central

    Alturkmani, Hani J.; Zgheib, Carlos; Zouein, Fouad A.; Alshaaer, Nour Eddin F.; Kurdi, Mazen; Booz, George W.

    2012-01-01

    Sodium selenate may have utility in treating Alzheimer’s disease and diabetes; however, its impact on the associated proinflammatory cytokine signaling of endothelial cells has not been investigated. We report that treatment of human microvascular endothelial cells with sodium selenate at a pharmacological dose (100 μM) enhanced tyrosine phosphorylation of nuclear STAT3 on Y705 in response to IL-6-type cytokine, leukemia inhibitory factor (LIF), indicative of enhanced STAT3 activity. Accordingly, STAT3 nuclear binding to DNA was increased, as well as LIF-induced gene expression of chemokine (C-C motif) ligand 2 (CCL2). CCL2 plays a key role in inflammatory processes associated with neuronal degenerative and vascular diseases. The enhancing action of selenate on LIF-induced STAT3 Y705 phosphorylation was replicated by vanadate and a specific inhibitor of protein tyrosine phosphatase, non-receptor type 1 (PTP1B). Moreover, we observed that selenite, the cellular reduction bioproduct of selenate but not selenate itself, inhibited enzymatic activity of human recombinant PTP1B. Our findings support the conclusion that in human microvascular endothelial cells selenate has a vanadate-like effect in inhibiting PTP1B and enhancing proinflammatory STAT3 activation. These findings raise the possibility that beneficial actions of supranutritional levels of selenate for treating Alzheimer’s and diabetes may be offset by a proinflammatory action on endothelial cells. PMID:22366233

  6. Selenate enhances STAT3 transcriptional activity in endothelial cells: differential actions of selenate and selenite on LIF cytokine signaling and cell viability.

    PubMed

    Alturkmani, Hani J; Zgheib, Carlos; Zouein, Fouad A; Alshaaer, Nour Eddin F; Kurdi, Mazen; Booz, George W

    2012-04-01

    Sodium selenate may have utility in treating Alzheimer's disease and diabetes; however, its impact on the associated proinflammatory cytokine signaling of endothelial cells has not been investigated. We report that treatment of human microvascular endothelial cells with sodium selenate at a pharmacological dose (100 μM) enhanced tyrosine phosphorylation of nuclear STAT3 on Y705 in response to IL-6-type cytokine, leukemia inhibitory factor (LIF), indicative of enhanced STAT3 activity. Accordingly, STAT3 nuclear binding to DNA was increased, as well as LIF-induced gene expression of chemokine (C-C motif) ligand 2 (CCL2). CCL2 plays a key role in inflammatory processes associated with neuronal degenerative and vascular diseases. The enhancing action of selenate on LIF-induced STAT3 Y705 phosphorylation was replicated by vanadate and a specific inhibitor of protein tyrosine phosphatase, non-receptor type 1 (PTP1B). Moreover, we observed that selenite, the cellular reduction bioproduct of selenate but not selenate itself, inhibited enzymatic activity of human recombinant PTP1B. Our findings support the conclusion that in human microvascular endothelial cells selenate has a vanadate-like effect in inhibiting PTP1B and enhancing proinflammatory STAT3 activation. These findings raise the possibility that beneficial actions of supranutritional levels of selenate for treating Alzheimer's and diabetes may be offset by a proinflammatory action on endothelial cells.

  7. Constitutive activation of signal transducer and activator of transcription 3 (STAT3) and nuclear factor κB signaling in glioblastoma cancer stem cells regulates the Notch pathway.

    PubMed

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

    2013-09-06

    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-κB 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-κB signaling pathway and up-regulation of STAT3- and NF-κB-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-κB 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-κB signaling pathways that leads to the regulation of Notch pathway genes in glioma CSCs identifies novel therapeutic targets for the treatment of glioma.

  8. YC-1 enhances the anti-tumor activity of sorafenib through inhibition of signal transducer and activator of transcription 3 (STAT3) in hepatocellular carcinoma

    PubMed Central

    2014-01-01

    Background Traditional systemic chemotherapy does not provide survival benefits in patients with hepatocellular carcinoma (HCC). Molecular targeted therapy shows promise for HCC treatment, however, the duration of effectiveness for targeted therapies is finite and combination therapies offer the potential for improved effectiveness. Methods Sorafenib, a multikinase inhibitor, and YC-1, a soluble guanylyl cyclase (sGC) activator, were tested in HCC by proliferation assay, cell cycle analysis and western blot in vitro and orthotopic and ectopic HCC models in vivo. Results In vitro, combination of sorafenib and YC-1 synergistically inhibited proliferation and colony formation of HepG2, BEL-7402 and HCCLM3 cells. The combination also induced S cell cycle arrest and apoptosis, as observed by activated PARP and caspase 8. Sorafenib and YC-1 respectively suppressed the expression of phosphorylated STAT3 (p-STAT3) (Y705) in a dose- and time-dependent manner. Combination of sorafenib and YC-1 significantly inhibited the expression of p-STAT3 (Y705) (S727), p-ERK1/2, cyclin D1 and survivin and SHP-1 activity compared with sorafenib or YC-1 used alone in all tested HCC cell lines. In vivo, sorafenib-YC-1 combination significantly suppressed the growth of HepG2 tumor xenografts with decreased cell proliferation and increased apoptosis observed by PCNA and PARP. Similar results were also confirmed in a HCCLM3 orthotopic model. There was a reduction in CD31-positive blood vessels and reduced VEGF expression, which suggested a combinational effect of sorafenib and YC-1 on angiogenesis. The reduced expression of p-STAT3, cyclin D1 and survivin was also observed with the combination of sorafenib and YC-1. Conclusions Our data show that sorafenib-YC-1 combination is a novel potent therapeutic agent that can target the STAT3 signaling pathway to inhibit HCC tumor growth. PMID:24418169

  9. The inflammatory/cancer-related IL-6/STAT3/NF-κB positive feedback loop includes AUF1 and maintains the active state of breast myofibroblasts

    PubMed Central

    Hendrayani, Siti-Fauziah; Al-Harbi, Bothaina; Al-Ansari, Mysoon M.; Silva, Gabriela; Aboussekhra, Abdelilah

    2016-01-01

    The IL-6/STAT3/NF-κB positive feedback loop links inflammation to cancer and maintains cells at a transformed state. Similarly, cancer-associated myofibroblats remains active even in absence of cancer cells. However, the molecular basis of this sustained active state remains elusive. We have shown here that breast cancer cells and IL-6 persistently activate breast stromal fibroblasts through the stimulation of the positive IL-6/STAT3/NF-κB feedback loop. Transient neutralization of IL-6 in culture inhibited this signaling circuit and reverted myofibrobalsts to a normalized state, suggesting the implication of the IL-6 autocrine feedback loop as well. Importantly, the IL-6/STAT3/NF-κB pro-inflammatory circuit was also active in cancer-associated fibroblasts isolated from breast cancer patients. Transient inhibition of STAT3 by specific siRNA in active fibroblasts persistently reduced the level of the RNA binding protein AUF1, blocked the loop and normalized these cells. Moreover, we present clear evidence that AUF1 is also part of this positive feedback loop. Interestingly, treatment of breast myofibroblasts with caffeine, which has been previously shown to persistently inhibit active breast stromal fibroblasts, blocked the positive feedback loop through potent and sustained inhibition of STAT3, AKT, lin28B and AUF1. These results indicate that the IL-6/STAT3/NF-κB positive feedback loop includes AUF1 and is responsible for the sustained active status of cancer-associated fibroblasts. We have also shown that normalizing myofibroblasts, which could be of great therapeutic value, is possible through the inhibition of this procarcinogenic circuit. PMID:27248826

  10. Sevoflurane postconditioning protects the myocardium against ischemia/reperfusion injury via activation of the JAK2–STAT3 pathway

    PubMed Central

    Wu, Jianjiang; Yu, Jin; Xie, Peng; Maimaitili, Yiliyaer; Wang, Jiang; Yang, Long; Ma, Haiping; Zhang, Xing; Yang, Yining

    2017-01-01

    Background Sevoflurane postconditioning (S-post) has similar cardioprotective effects as ischemic preconditioning. However, the underlying mechanism of S-post has not been fully elucidated. Janus kinase signaling transduction/transcription activator (JAK2–STAT3) plays an important role in cardioprotection. The purpose of this study was to determine whether the cardioprotective effects of S-post are associated with activation of the JAK2–STAT3 signal pathway. Methods An adult male Sprague–Dawley (SD) rat model of myocardial ischemia/reperfusion (I/R) injury was established using the Langendorff isolated heart perfusion apparatus. At the beginning of reperfusion, 2.4% sevoflurane alone or in combination with AG490 (a JAK2 selective inhibitor) was used as a postconditioning treatment. The cardiac function indicators, myocardial infarct size, lactic dehydrogenase (LDH) release, mitochondrial ultrastructure, mitochondrial reactive oxygen species (ROS) generation rates, ATP content, protein expression of p-JAK, p-STAT3, Bcl-2 and Bax were measured. Results Compared with the I/R group, S-post significantly increased the expression of p-JAK, p-STAT3 and Bcl-2 and reduced the protein expression of Bax, which markedly decreased the myocardial infarction areas, improved the cardiac function indicators and the mitochondrial ultrastructure, decreased the mitochondrial ROS and increased the ATP content. However, the cardioprotective effects of S-post were abolished by treatment with a JAK2 selective inhibitor (p < 0.05). Conclusion This study demonstrates that the cardioprotective effects of S-post are associated with the activation of JAK2–STAT3. The mechanism may be related to an increased expression of p-JAK2 and p-STAT3 after S-post, which reduced mitochondrial ROS generation and increased mitochondrial ATP content, thereby reducing apoptosis and myocardial infarct size. PMID:28392989

  11. Qing Hua Chang Yin inhibits the LPS-induced activation of the IL-6/STAT3 signaling pathway in human intestinal Caco-2 cells.

    PubMed

    Ke, Xiao; Hu, Guanghong; Fang, Wenyi; Chen, Jintuan; Zhang, Xin; Yang, Chunbo; Peng, Jun; Chen, Youqin; Sferra, Thomas J

    2015-04-01

    Increasing evidence indicates that the pathogenesis of ulcerative colitis (UC) is highly regulated by the interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) pathway and its negative feedback regulator, suppressor of cytokine signaling 3 (SOCS3). Therefore, modulating the signaling feedback loop of IL-6/STAT3/SOCS3 may prove to be a novel therapeutic approach for the treatment of UC. Qing Hua Chang Yin (QHCY) is a traditional Chinese formulation that has long been used in clinic for the treatment of UC. We have previously reported that QHCY ameliorates acute intestinal inflammation in vivo and in vitro through the suppression of the nuclear factor-κB (NF-κB) pathway. In the present study, in order to further elucidate the mechanisms responsible for the anti-inflammatory activities of QHCY, we stimulated human intestinal Caco-2 cells with lipopolysaccharide (LPS) to create an in vitro model of an inflamed human intestinal epithelium, and evaluated the effects of QHCY on the IL-6/STAT3/SOCS3 signaling network in inflamed Caco-2 cells. The levels of IL-6 were measured by ELISA and the levels of STAT3 and SOCS3 were measured by western blot analysis. We found that QHCY significantly inhibited the LPS-induced secretion of pro-inflammatory IL-6 in the Caco-2 cells in a dose-dependent manner. Moreover, QHCY profoundly suppressed the LPS-induced phosphorylation of Janus-activated kinase 1 (JAK1), JAK2 and STAT3. Furthermore, treatment with QHCY markedly augmented the expression of SOCS3. Taken together, the findings of the present study suggest that the modulation of the IL-6/STAT3/SOCS3 signaling network may be one of the mechanisms through which QHCY exerts its anti-inflammatory effects.

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

    PubMed

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

    2012-11-01

    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.

  13. Novel small molecular inhibitors disrupt the JAK/STAT3 and FAK signaling pathways and exhibit a potent antitumor activity in glioma cells.

    PubMed

    Swiatek-Machado, Karolina; Mieczkowski, Jakub; Ellert-Miklaszewska, Aleksandra; Swierk, Piotr; Fokt, Izabela; Szymanski, Slawomir; Skora, Stanislaw; Szeja, Wiesław; Grynkiewicz, Grzegorz; Lesyng, Bogdan; Priebe, Waldemar; Kaminska, Bozena

    2012-06-01

    JAK (Janus kinase)/STAT (signal transducers and activators of transcription) signaling is involved in the regulation of cell growth, differentiation and apoptosis. Constitutive activation of STATs, in particular STAT3, is observed in a large number of human tumors, including gliomas and may contribute to oncogenesis by stimulating cell proliferation and preventing apoptosis, thus it emerges as a promising target for anti-cancer therapy. To investigate the therapeutic potential of blocking STAT3 in glioma cells a set of small synthetic molecules - caffeic acid derivatives, structurally related to AG490 was screened for its ability to inhibit STAT3. Inhibitor 2 (E)-2-cyano-N-[(S)-1-phenylethyl]-3-(pyridin-2-yl)acrylamide was the most effective in inhibition of JAK/STAT3 signaling and at doses ≥ 25 μM significantly reduced the level of phosphorylated JAK1, JAK2 and STAT3 (at Tyr705) and downregulated the expression of known STAT3 targets. In treated cells we observed rapid detachment and rounding of cells associated with reduction of focal adhesion kinase phosphorylation and activity, followed by upregulation of phosphorylated p38, JNK and ERK1/2 levels. Accumulation of cells with fragmented DNA, increases of the cleaved caspase 3 and fragmented PARP levels were detected 24 h after the treatment suggesting ongoing apoptotic cell death. Three human malignant glioblastoma cell lines defective in tumor suppressors TP53 and/or PTEN were susceptible to inhibitor 2 that induced the programmed cell death. Global gene expression profiling revealed modulation of numerous genes in cells treated with inhibitor 2 revealing novel, potential JAK/STAT targets. Our study demonstrates that suitably modified caffeic acid molecules exhibit significant cytotoxic potential toward glioma cells.

  14. 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

  15. Soluble egg antigens of Schistosoma japonicum induce senescence in activated hepatic stellate cells by activation of the STAT3/p53/p21 pathway

    PubMed Central

    Chen, Jinling; Pan, Jing; Wang, Jianxin; Song, Ke; Zhu, Dandan; Huang, Caiqun; Duan, Yinong

    2016-01-01

    Liver fibrosis is characterized by the activation of hepatic stellate cells (HSCs). Recent findings suggest that senescence of activated HSCs might limit the development of liver fibrosis. Based on previously observed anti-fibrotic effects of soluble egg antigens from Schistosoma japonicum in vitro, we hypothesized that SEA might play a crucial role in alleviating liver fibrosis through promoting senescence of activated HSCs. We show here that SEA inhibited expression of α-SMA and pro-collagen I and promoted senescence of activated HSCs in vitro. In addition, SEA induced an increased expression of P-p53 and p21. Knockdown of p53 inhibited the expression of p21 and failed to induce senescence of activated-HSCs. Phosphorylated STAT3 was elevated upon SEA stimulation, while loss of STAT3 decreased the level of p53 and senescence of HSCs. Results from immunoprecipitation analysis demonstrated that SOCS3 might be involved in the SEA-induced senescence in HSCs through its interaction with p53. This study demonstrates the potential capacity of SEA in restricting liver fibrosis through promoting senescence in HSCs. Furthermore, a novel STAT3-p53-p21 pathway might participate in the observed SEA-mediated senescence of HSCs. Our results suggest that SEA might carry potential therapeutic effects of restraining liver fibrosis through promoting senescence. PMID:27489164

  16. MDM2 facilitates adipocyte differentiation through CRTC-mediated activation of STAT3

    PubMed Central

    Hallenborg, P; Siersbæk, M; Barrio-Hernandez, I; Nielsen, R; Kristiansen, K; Mandrup, S; Grøntved, L; Blagoev, B

    2016-01-01

    The ubiquitin ligase MDM2 is best known for balancing the activity of the tumor suppressor p53. We have previously shown that MDM2 is vital for adipocyte conversion through controlling Cebpd expression in a p53-independent manner. Here, we show that the proadipogenic effect of MDM2 relies on activation of the STAT family of transcription factors. Their activation was required for the cAMP-mediated induction of target genes. Interestingly, rather than influencing all cAMP-stimulated genes, inhibition of the kinases directly responsible for STAT activation, namely JAKs, or ablation of MDM2, each resulted in abolished induction of a subset of cAMP-stimulated genes, with Cebpd being among the most affected. Moreover, STATs were able to interact with the transcriptional cofactors CRTC2 and CRTC3, hitherto only reported to associate with the cAMP-responsive transcription factor CREB. Last but not least, the binding of CRTC2 to a transcriptional enhancer that interacts with the Cebpd promoter was dramatically decreased upon JAK inhibition. Our data reveal the existence of an unusual functional interplay between STATs and CREB at the onset of adipogenesis through shared CRTC cofactors. PMID:27362806

  17. CD5 costimulation induces stable Th17 development by promoting IL-23R expression and sustained STAT3 activation.

    PubMed

    de Wit, Jelle; Souwer, Yuri; van Beelen, Astrid J; de Groot, Rosa; Muller, Femke J M; Klaasse Bos, Hanny; Jorritsma, Tineke; Kapsenberg, Martien L; de Jong, Esther C; van Ham, S Marieke

    2011-12-01

    IL-17-producing CD4(+) T helper (Th17) cells are important for immunity against extracellular pathogens and in autoimmune diseases. The factors that drive Th17 development in human remain a matter of debate. Here we show that, compared with classic CD28 costimulation, alternative costimulation via the CD5 or CD6 lymphocyte receptors forms a superior pathway for human Th17-priming. In the presence of the Th17-promoting cytokines IL-1β, IL-6, IL-23, and transforming growth factor-β (TGF-β), CD5 costimulation induces more Th17 cells that produce higher amounts of IL-17, which is preceded by prolonged activation of signal transducer and activator of transcription 3 (STAT3), a key regulator in Th17 differentiation, and enhanced levels of the IL-17-associated transcription factor retinoid-related orphan receptor-γt (ROR-γt). Strikingly, these Th17-promoting signals critically depend on CD5-induced elevation of IL-23 receptor (IL-23R) expression. The present data favor the novel concept that alternative costimulation via CD5, rather than classic costimulation via CD28, primes naive T cells for stable Th17 development through promoting the expression of IL-23R.

  18. TNF-α-inducing protein of Helicobacter pylori induces epithelial-mesenchymal transition (EMT) in gastric cancer cells through activation of IL-6/STAT3 signaling pathway.

    PubMed

    Chen, Guodong; Tang, Na; Wang, Chao; Xiao, Linqiao; Yu, Minjun; Zhao, Lanhua; Cai, Hengling; Han, Liang; Xie, Chengyuan; Zhang, Yan

    2017-03-04

    Tumor necrosis factor (TNF)-α-inducing protein (Tipα) is a newly identified carcinogenic factor secreted by Helicobacter pylori (H. pylori). Although it has been proved that Tipα is a strong inducer of epithelial-mesenchymal transition (EMT), a crucial process of migration, the exact molecular mechanism is unknown. Current evidence indicates that the oncogenic transcription factor signal transducers and activators of transcription 3 (STAT3) is inappropriately activated in multiple malignancies, including gastric cancer. In this study, we showed that Tipα significantly down-regulated the expression of EMT-related markers E-cadherin as well as up-regulated N-cadherin and vimentin in SGC7901 cells, with typical morphological changes of EMT. Tipα also promoted proliferation and migration of SGC7901 cells. Furthermore, Tipα activated interleukin-6 (IL-6)/STAT3 signaling pathway in SGC7901 cells. The effects of Tipα treatment observed was abolished when we block IL-6/STAT3 signaling pathway. Altogether, our data demonstrated that Tipα may accelerate tumor aggressiveness in gastric cancer by promoting EMT through activation of IL-6/STAT3 pathway.

  19. Th17-type cytokines, IL-6 and TNF-α synergistically activate STAT3 and NF-kB to promote colorectal cancer cell growth.

    PubMed

    De Simone, V; Franzè, E; Ronchetti, G; Colantoni, A; Fantini, M C; Di Fusco, D; Sica, G S; Sileri, P; MacDonald, T T; Pallone, F; Monteleone, G; Stolfi, C

    2015-07-01

    Colorectal cancers (CRCs) often show a dense infiltrate of cytokine-producing immune/inflammatory cells. The exact contribution of each immune cell subset and cytokine in the activation of the intracellular pathways sustaining CRC cell growth is not understood. Herein, we isolate tumor-infiltrating leukocytes (TILs) and lamina propria mononuclear cells (LPMCs) from the tumor area and the macroscopically unaffected, adjacent, colonic mucosa of patients who underwent resection for sporadic CRC and show that the culture supernatants of TILs, but not of LPMCs, potently enhance the growth of human CRC cell lines through the activation of the oncogenic transcription factors signal transducer and activator of transcription 3 (STAT3) and nuclear factor-kappa B (NF-kB). Characterization of immune cell complexity of TILs and LPMCs reveals no differences in the percentages of T cells, natural killer T cells, natural killer (NK) cells, macrophages and B cells. However, T cells from TILs show a functional switch compared with those from LPMCs to produce large amounts of T helper type 17 (Th17)-related cytokines (that is, interleukin-17A (IL-17A), IL-17F, IL-21 and IL-22), tumor necrosis factor-α (TNF-α) and IL-6. Individual neutralization of IL-17A, IL-17F, IL-21, IL-22, TNF-α or IL-6 does not change TIL-derived supernatant-driven STAT3 and NF-kB activation, as well as their proproliferative effect in CRC cells. In contrast, simultaneous neutralization of both IL-17A and TNF-α, which abrogates NF-kB signaling, and IL-22 and IL-6, which abrogates STAT3 signaling, reduces the mitogenic effect of supernatants in CRC cells. IL-17A, IL-21, IL-22, TNF-α and IL-6 are also produced in excess in the early colonic lesions in a mouse model of sporadic CRC, associated with enhanced STAT3/NF-kB activation. Mice therapeutically given BP-1-102, an orally bioavailable compound targeting STAT3/NF-kB activation and cross-talk, exhibit reduced colon tumorigenesis and diminished expression of

  20. CD44 and CD24 coordinate the reprogramming of nasopharyngeal carcinoma cells towards a cancer stem cell phenotype through STAT3 activation

    PubMed Central

    Shen, Yao-An; Wang, Chia-Yu; Chuang, Hui-Yen; Hwang, John Jeng-Jong; Chi, Wei-Hsin; Shu, Chih-Hung; Ho, Ching-Yin; Li, Wing-Yin; Chen, Yann-Jang

    2016-01-01

    Cell surface proteins such as CD44 and CD24 are used to distinguish cancer stem cells (CSCs) from the bulk-tumor population. However, the molecular functionalities of CD24 and CD44, and how these two molecules coordinate in CSCs remain poorly understood. We found that nasopharyngeal carcinoma (NPC) cells with high expression of CD44 and CD24 proteins presented with pronounced CSC properties. Accordingly, a subpopulation of NPC cells with co-expression of CD44 and CD24 were specially enriched in high-stage clinical samples. Furthermore, ectopically expressing the epithelial-mesenchymal transition (EMT) regulator Twist was able to upregulate the stemness factors, and vice versa. This indicates a reciprocal regulation of stemness and EMT. Intriguingly, we found that this reciprocal regulation was differentially orchestrated by CD44 and CD24, and only simultaneous silencing the expression of CD44 and CD24 led to a broad-spectrum suppression of CSC properties. Oppositely, overexpression of CD44 and CD24 induced the reprogramming of parental NPC cells into CSCs through STAT3 activation, which could be blunted by STAT3 inhibition, indicating that CD44 and CD24 collaboratively drive the reprogramming of NPC cells through STAT3-mediated stemness and EMT activation. Consequently, targeting of the CD44/CD24/STAT3 axis may provide a potential therapeutic paradigm for the treatment of NPC through repressing CSC activities. PMID:27521216

  1. The ETS factor ESE3/EHF represses IL-6 preventing STAT3 activation and expansion of the prostate cancer stem-like compartment

    PubMed Central

    Albino, Domenico; Civenni, Gianluca; Rossi, Simona; Mitra, Abhishek; Catapano, Carlo V.; Carbone, Giuseppina M.

    2016-01-01

    Metastatic prostate cancer represents a yet unsolved clinical problem due to the high frequency of relapse and treatment resistance. Understanding the pathways that lead to prostate cancer progression is an important task to prevent this deadly disease. The ETS transcription factor ESE3/EHF has an important role in differentiation of human prostate epithelial cells. Loss of ESE3/EHF in prostate epithelial cells determines transformation, epithelial-to-mesenchymal transition (EMT) and acquisition of stem-like properties. In this study we identify IL-6 as a direct target of ESE3/EHF that is activated in prostate epithelial cells upon loss of ESE3/EHF. ESE3/EHF and IL-6 were significantly inversely correlated in prostate tumors. Chromatin immunoprecipitation confirmed binding of ESE3/EHF to a novel ETS binding site in the IL-6 gene promoter. Inhibition of IL-6 reverted transformation and stem-like phenotype in tumorigenic ESE3/EHF knockdown prostate epithelial cell models. Conversely, IL-6 stimulation induced malignant phenotypes, stem-like behavior and STAT3 activation. Increased level of IL-6 was observed in prostatospheres compared with adherent bulk cancer cells and this was associated with stronger activation of STAT3. Human prostate tumors with IL-6 elevation and loss of ESE3/EHF were associated with STAT3 activation and displayed upregulation of genes related to cell adhesion, cancer stem-like and metastatic spread. Pharmacological inhibition of IL-6/STAT3 activation by a JAK inhibitor restrained cancer stem cell growth in vitro and inhibited self-renewal in vivo. This study identifies a novel connection between the transcription factor ESE3/EHF and the IL-6/JAK/STAT3 pathway and suggests that targeting this axis might be preferentially beneficial in tumors with loss of ESE3/EHF. PMID:27732936

  2. Photodynamic therapy activated signaling from epidermal growth factor receptor and STAT3: Targeting survival pathways to increase PDT efficacy in ovarian and lung cancer.

    PubMed

    Edmonds, Christine; Hagan, Sarah; Gallagher-Colombo, Shannon M; Busch, Theresa M; Cengel, Keith A

    2012-12-01

    Patients with serosal (pleural or peritoneal) spread of malignancy have few definitive treatment options and consequently have a very poor prognosis. We have previously shown that photodynamic therapy (PDT) can be an effective treatment for these patients, but that the therapeutic index is relatively narrow. Here, we test the hypothesis that EGFR and STAT3 activation increase survival following PDT, and that inhibiting these pathways leads to increased PDT-mediated direct cellular cytotoxicity by examining BPD-PDT in OvCa and NSCLC cells. We found that BPD-mediated PDT stimulated EGFR tyrosine phosphorylation and nuclear translocation, and that EGFR inhibition by erlotinib resulted in reduction of PDT-mediated EGFR activation and nuclear translocation. Nuclear translocation and PDT-mediated activation of EGFR were also observed in response to BPD-mediated PDT in multiple cell lines, including OvCa, NSCLC and head and neck cancer cells, and was observed to occur in response to porfimer sodium-mediated PDT. In addition, we found that PDT stimulates nuclear translocation of STAT3 and STAT3/EGFR association and that inhibiting STAT3 signaling prior to PDT leads to increased PDT cytotoxicity. Finally, we found that inhibition of EGFR signaling leads to increased PDT cytotoxicity through a mechanism that involves increased apoptotic cell death. Taken together, these results demonstrate that PDT stimulates the nuclear accumulation of both EGFR and STAT3 and that targeting these survival pathways is a potentially promising strategy that could be adapted for clinical trials of PDT for patients with serosal spread of malignancy.

  3. Leptin-induced Growth Stimulation of Breast Cancer Cells Involves Recruitment of Histone Acetyltransferases and Mediator Complex to CYCLIN D1 Promoter via Activation of Stat3*

    PubMed Central

    Saxena, Neeraj K.; Vertino, Paula M.; Anania, Frank A.; Sharma, Dipali

    2010-01-01

    Numerous epidemiological studies documented that obesity is a risk factor for breast cancer development in postmenopausal women. Leptin, the key player in the regulation of energy balance and body weight control also acts as a growth factor on certain organs in both normal and disease state. In this study, we analyzed the role of leptin and the molecular mechanism(s) underlying its action in breast cancer cells that express both short and long isoforms of leptin receptor. Leptin increased MCF7 cell population in the S-phase of the cell cycle along with a robust increase in CYCLIN D1 expression. Also, leptin induced Stat3-phosphorylation-dependent proliferation of MCF7 cells as blocking Stat3 phosphorylation with a specific inhibitor, AG490, abolished leptin-induced proliferation. Using deletion constructs of CYCLIN D1 promoter and chromatin immunoprecipitation assay, we show that leptin induced increase in CYCLIN D1 promoter activity is mediated through binding of activated Stat3 at the Stat binding sites and changes in histone acetylation and methylation. We also show specific involvement of coactivator molecules, histone acetyltransferase SRC1, and mediator complex in leptin-mediated regulation of CYCLIN D1 promoter. Importantly, silencing of SRC1 and Med1 abolished the leptin induced increase in CYCLIN D1 expression and MCF7 cell proliferation. Intriguingly, recruitment of both SRC1 and Med1 was dependent on phosphorylated Stat3 as AG490 treatment inhibited leptin-induced recruitment of these coactivators to CYCLIN D1 promoter. Our data suggest that CYCLIN D1 may be a target gene for leptin mediated growth stimulation of breast cancer cells and molecular mechanisms involve activated Stat3-mediated recruitment of distinct coactivator complexes. PMID:17344214

  4. p53 induces miR199a-3p to suppress SOCS7 for STAT3 activation and renal fibrosis in UUO

    PubMed Central

    Yang, Ruhao; Xu, Xuan; Li, Huiling; Chen, Jinwen; Xiang, Xudong; Dong, Zheng; Zhang, Dongshan

    2017-01-01

    The role of p53 in renal fibrosis has recently been suggested, however, its function remains controversial and the underlying mechanism is unclear. Here, we show that pharmacological and genetic blockade of p53 attenuated renal interstitial fibrosis, apoptosis, and inflammation in mice with unilateral urethral obstruction (UUO). Interestingly, p53 blockade was associated with the suppression of miR-215-5p, miR-199a-5p&3p, and STAT3. In cultured human kidney tubular epithelial cells (HK-2), TGF-β1 treatment induced fibrotic changes, including collagen I and vimentin expression, being associated with p53 accumulation, p53 Ser15 phosphorylation, and miR-199a-3p expression. Inhibition of p53 by pifithrin-α blocked STAT3 activation and the expression of miR-199a-3p, collagen I, and vimentin during TGF-β1 treatment. Over-expression of miR-199a-3p increased TGFβ1-induced collagen I and vimentin expression and restored SOCS7 expression. Furthermore, SOCS7 was identified as a target gene of miR-199a-3p, and silencing of SOCS7 promoted STAT3 activation. ChIp analyses indicated the binding of p53 to the promoter region of miR-199a-3p. Consistently, kidney biopsies from patients with IgA nephropathy and diabetic nephropathy exhibited substantial activation of p53 and STAT3, decreased expression of SOCS7, and increase in profibrotic proteins and miR-199a-3p. Together, these results demonstrate the novel p53/miR-199a-3p/SOCS7/STAT3 pathway in renal interstitial fibrosis. PMID:28240316

  5. Entinostat up-regulates the CAMP gene encoding LL-37 via activation of STAT3 and HIF-1α transcription factors

    PubMed Central

    Miraglia, Erica; Nylén, Frank; Johansson, Katarina; Arnér, Elias; Cebula, Marcus; Farmand, Susan; Ottosson, Håkan; Strömberg, Roger; Gudmundsson, Gudmundur H.; Agerberth, Birgitta; Bergman, Peter

    2016-01-01

    Bacterial resistance against classical antibiotics is a growing problem and the development of new antibiotics is limited. Thus, novel alternatives to antibiotics are warranted. Antimicrobial peptides (AMPs) are effector molecules of innate immunity that can be induced by several compounds, including vitamin D and phenyl-butyrate (PBA). Utilizing a luciferase based assay, we recently discovered that the histone deacetylase inhibitor Entinostat is a potent inducer of the CAMP gene encoding the human cathelicidin LL-37. Here we investigate a mechanism for the induction and also find that Entinostat up-regulates human β-defensin 1. Analysis of the CAMP promoter sequence revealed binding sites for the transcription factors STAT3 and HIF-1α. By using short hairpin RNA and selective inhibitors, we found that both transcription factors are involved in Entinostat-induced expression of LL-37. However, only HIF-1α was found to be recruited to the CAMP promoter, suggesting that Entinostat activates STAT3, which promotes transcription of CAMP by increasing the expression of HIF-1α. Finally, we provide in vivo relevance to our findings by showing that Entinostat-elicited LL-37 expression was impaired in macrophages from a patient with a STAT3-mutation. Combined, our findings support a role for STAT3 and HIF-1α in the regulation of LL-37 expression. PMID:27633343

  6. 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.

  7. 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

  8. 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

    2015-01-01

    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.

  9. Acrp30 inhibits leptin-induced metastasis by downregulating the JAK/STAT3 pathway via AMPK activation in aggressive SPEC-2 endometrial cancer cells.

    PubMed

    Wu, Xiaomei; Yan, Qin; Zhang, Zhenbo; Du, Guiqiang; Wan, Xiaoping

    2012-05-01

    Obesity is a well-established risk factor for endometrial cancer, due in part to the adipokines generated by adipose tissue, such as adiponectin (also known as Acrp30) and leptin, which are associated with many endocrine-related cancers. Recent reports suggested that Acrp30 inhibits leptin-stimulated cell proliferation in HEC-1A and RL95-2 endometrial cancer cell lines, and that the serum leptin/Acrp30 ratio plays an important role in endometrial cancer development. We explored whether Acrp30 could reverse the leptin-induced metastasis phenotype in the SPEC-2 endometrial cancer cell line. Transcripts for Acrp30 receptors (AdipoR1 and AdipoR2) and leptin receptor (Ob-Rb) were detected by quantitative real-time RT-PCR (qRT-PCR) in six endometrial cancer cell lines. Leptin (1 µg/ml) treatment stimulated SPEC-2 cell proliferation by inducing cell cycle arrest and apoptosis, while Acrp30 (10 µg/ml) treatment inhibited the growth of SPEC-2 cells. Importantly, Acrp30 was able to inhibit leptin-induced SPEC-2 cell proliferation. Leptin promoted SPEC-2 cell invasion in a Matrigel transwell assay, while Acrp30 partly suppressed the invasion stimulated by leptin. To investigate the molecular mechanism underlying this phenomenon, we monitored the AMPK and JAK/STAT3 signaling pathways by western blotting and cell immunofluorescence. Acrp30 reduced leptin-induced STAT3 phosphorylation and nuclear translocation via activation of the MAPK pathway. AG490 (JAK/STAT3 inhibitor) reduced MMP-2 and MMP-9 protein levels in cells treated with leptin, while IL-6 (JAK/STAT3 stimulator) and Compound C (AMPK inhibitor) elevated MMP-2 and MMP-9 protein levels in cells treated with Acrp30. In conclusion, we demonstrated that Acrp30 effectively reversed the invasion stimulated by leptin, and AMPK and JAK/STAT3 pathways mediated the invasive phenotype of SPEC-2 cells.

  10. NTRK2 activation cooperates with PTEN deficiency in T-ALL through activation of both the PI3K–AKT and JAK–STAT3 pathways

    PubMed Central

    Yuzugullu, Haluk; Von, Thanh; Thorpe, Lauren M; Walker, Sarah R; Roberts, Thomas M; Frank, David A; Zhao, Jean J

    2016-01-01

    Loss of PTEN, a negative regulator of the phosphoinositide 3-kinase signaling pathway, is a frequent event in T-cell acute lymphoblastic leukemia, suggesting the importance of phosphoinositide 3-kinase activity in this disease. Indeed, hyperactivation of the phosphoinositide 3-kinase pathway is associated with the disease aggressiveness, poor prognosis and resistance to current therapies. To identify a molecular pathway capable of cooperating with PTEN deficiency to drive oncogenic transformation of leukocytes, we performed an unbiased transformation screen with a library of tyrosine kinases. We found that activation of NTRK2 is able to confer a full growth phenotype of Ba/F3 cells in an IL3-independent manner in the PTEN-null setting. NTRK2 activation cooperates with PTEN deficiency through engaging both phosphoinositide3-kinase/AKT and JAK/STAT3 pathway activation in leukocytes. Notably, pharmacological inhibition demonstrated that p110α and p110δ are the major isoforms mediating the phosphoinositide 3-kinase/AKT signaling driven by NTRK2 activation in PTEN-deficient leukemia cells. Furthermore, combined inhibition of phosphoinositide 3-kinase and STAT3 significantly suppressed proliferation of PTEN-mutant T-cell acute lymphoblastic leukemia both in culture and in mouse xenografts. Together, our data suggest that a unique conjunction of PTEN deficiency and NTRK2 activation in T-cell acute lymphoblastic leukemia, and combined pharmacologic inhibition of phosphoinositide 3-kinase and STAT3 signaling may serve as an effective and durable therapeutic strategy for T-cell acute lymphoblastic leukemia. PMID:27672444

  11. Lumbar puncture-administered resveratrol inhibits STAT3 activation, enhancing autophagy and apoptosis in orthotopic rat glioblastomas

    PubMed Central

    Xue, Song; Xiao-Hong, Shu; Lin, Sha; Jie, Bian; Li-Li, Wang; Jia-Yao, Gu; Shun, Shi; Pei-Nan, Li; Mo-Li, Wu; Qian, Wang; Xiao-Yan, Chen; Qing-You, Kong; Peng, Zhang; Hong, Li; Jia, Liu

    2016-01-01

    Trans-resveratrol suppresses glioblastoma growth in vitro, but its effects on intracranial glioblastomas remain untested. Resveratrol crosses the blood–brain barrier, and lumbar puncture (LP) greatly increases its bioavailability in rat brains; therefore, we investigated the effectiveness of LP-administered resveratrol on orthotopic rat glioblastomas. Twenty-four tumor-bearing rats were separated into two groups: Group 1 receiving 100 μl saline containing 0.3% DMSO and Group 2 receiving 100 μl resveratrol (300 μM). Treatments started 3 days after transplantation in 2-day intervals until death. Intracranial drug availabilities, tumor sizes, average life spans and the impacts on STAT3 signaling, apoptosis and autophagy rates were evaluated. MRI imaging revealed that average tumor size in the LP group (495.8 ± 22.3 mm2) was smaller than the control groups (810.3 ± 56.4 mm2; P<0.05). The mean survival time in the LP group (22.2 ± 2.1 d) was longer than control animals (16.0 ± 1.8 d; P<0.05). LP resveratrol-treated glioblastomas showed less Cyclin D1 staining, enhanced autophagy with up-regulated LC3 and Beclin1 expression, and widely distributed apoptotic foci around tumor capillaries with suppressed STAT3 expression and nuclear translocation. In conclusion, LP-delivered resveratrol efficiently inhibited orthotopic rat glioblastoma growth by inactivating STAT3 signaling and enhancing autophagy and apoptosis. PMID:27716625

  12. Salinomycin Promotes Anoikis and Decreases the CD44+/CD24- Stem-Like Population via Inhibition of STAT3 Activation in MDA-MB-231 Cells.

    PubMed

    An, Hyunsook; Kim, Ji Young; Oh, Eunhye; Lee, Nahyun; Cho, Youngkwan; Seo, Jae Hong

    2015-01-01

    Triple-negative breast cancer (TNBC) is an aggressive tumor subtype with an enriched CD44+/CD24- stem-like population. Salinomycin is an antibiotic that has been shown to target cancer stem cells (CSC); however, the mechanisms of action involved have not been well characterized. The objective of the present study was to investigate the effect of salinomycin on cell death, migration, and invasion, as well as CSC-like properties in MDA-MB-231 breast cancer cells. Salinomycin significantly induced anoikis-sensitivity, accompanied by caspase-3 and caspase-8 activation and PARP cleavage, during anchorage-independent growth. Salinomycin treatment also caused a marked suppression of cell migration and invasion with concomitant downregulation of MMP-9 and MMP-2 mRNA levels. Notably, salinomycin inhibited the formation of mammospheres and effectively reduced the CD44+/CD24- stem-like population during anchorage-independent growth. These observations were associated with the inhibition of STAT3 phosphorylation (Tyr705). Furthermore, interleukin-6 (IL-6)-induced STAT3 activation was strongly suppressed by salinomycin challenge. These findings support the notion that salinomycin may be potentially efficacious for targeting breast cancer stem-like cells through the inhibition of STAT3 activation.

  13. Cell confluency-induced Stat3 activation regulates NHE3 expression by recruiting Sp1 and Sp3 to the proximal NHE3 promoter region during epithelial dome formation.

    PubMed

    Su, Hsiao-Wen; Wang, Shainn-Wei; Ghishan, Fayez K; Kiela, Pawel R; Tang, Ming-Jer

    2009-01-01

    Activation of signal transducer and activator of transcription-3 (Stat3) during cell confluency is related to its regulatory roles in cell growth arrest- or survival-related physiological or developmental processes. We previously demonstrated that this signaling event triggers epithelial dome formation by transcriptional augmentation of sodium hydrogen exchanger-3 (NHE3) expression. However, the detailed molecular mechanism remained unclear. By using serial deletions, site-directed mutagenesis, and EMSA analysis, we now demonstrate Stat3 binding to an atypical Stat3-response element in the rat proximal NHE3 promoter, located adjacent to a cluster of Sp cis-elements (SpA/B/C), within -77/-36 nt of the gene. SpB (-58/-55 nt) site was more effective than SpA (-72/-69 nt) site for cooperative binding of Sp1/Sp3. Increasing cell density had no effect on Sp1/Sp3 expression but resulted in their increased binding to the SpA/B/C probe along with Stat3 and concurrently with enhanced nuclear pTyr705-Stat3 level. Immunoprecipitation performed with the nuclear extracts demonstrated physical interaction of Stat3 and Sp1/Sp3 triggered by cell confluency. Stat3 inhibition by overexpression of dominant-negative Stat3-D mutant in MDCK cells or by small interfering RNA-mediated knockdown in Caco-2 cells resulted in inhibition of the cell density-induced NHE3 expression, Sp1/Sp3 binding, and NHE3 promoter activity and in decreased dome formation. Thus, during confluency, ligand-independent Stat3 activation leads to its interaction with Sp1/Sp3, their recruitment to the SpA/B/C cluster in a Stat3 DNA-binding domain-dependent fashion, increased transcription, and expression of NHE3, to coordinate cell density-mediated epithelial dome formation.

  14. Autocrine activity of BDNF induced by the STAT3 signaling pathway causes prolonged TrkB activation and promotes human non-small-cell lung cancer proliferation

    PubMed Central

    Chen, Bo; Liang, Yan; He, Zheng; An, Yunhe; Zhao, Weihong; Wu, Jianqing

    2016-01-01

    Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin superfamily, which has been implicated in the pathophysiology of the nervous system. Recently, several studies have suggested that BDNF and/or its receptor, tropomyosin related kinase B (TrkB), are involved in tumor growth and metastasis in several cancers, including prostate cancer, neuroblastoma, pancreatic ductal carcinoma, hepatocellular carcinoma, and lung cancer. Despite the increasing emphasis on BDNF/TrkB signaling in human tumors, how it participates in primary tumors has not yet been determined. Additionally, little is known about the molecular mechanisms that elicit signaling downstream of TrkB in the progression of non-small-cell lung cancer (NSCLC). In this study, we report the significant expression of BDNF in NSCLC samples and show that BDNF stimulation increases the synthesis of BDNF itself through activation of STAT3 in lung cancer cells. The release of BDNF can in turn activate TrkB signaling. The activation of both TrkB and STAT3 contribute to downstream signaling and promote human non-small-cell lung cancer proliferation. PMID:27456333

  15. Oncogenic transformation of human lung bronchial epithelial cells induced by arsenic involves ROS-dependent activation of STAT3-miR-21-PDCD4 mechanism

    PubMed Central

    Pratheeshkumar, Poyil; Son, Young-Ok; Divya, Sasidharan Padmaja; Wang, Lei; Zhang, Zhuo; Shi, Xianglin

    2016-01-01

    Arsenic is a well-documented human carcinogen. The present study explored the role of the onco-miR, miR-21 and its target protein, programmed cell death 4 (PDCD4) in arsenic induced malignant cell transformation and tumorigenesis. Our results showed that treatment of human bronchial epithelial (BEAS-2B) cells with arsenic induces ROS through p47phox, one of the NOX subunits that is the key source of arsenic-induced ROS. Arsenic exposure induced an upregulation of miR-21 expression associated with inhibition of PDCD4, and caused malignant cell transformation and tumorigenesis of BEAS-2B cells. Indispensably, STAT3 transcriptional activation by IL-6 is crucial for the arsenic induced miR-21 increase. Upregulated miR-21 levels and suppressed PDCD4 expression was also observed in xenograft tumors generated with chronic arsenic exposed BEAS-2B cells. Stable shut down of miR-21, p47phox or STAT3 and overexpression of PDCD4 or catalase in BEAS-2B cells markedly inhibited the arsenic induced malignant transformation and tumorigenesis. Similarly, silencing of miR-21 or STAT3 and forced expression of PDCD4 in arsenic transformed cells (AsT) also inhibited cell proliferation and tumorigenesis. Furthermore, arsenic suppressed the downstream protein E-cadherin expression and induced β-catenin/TCF-dependent transcription of uPAR and c-Myc. These results indicate that the ROS-STAT3-miR-21-PDCD4 signaling axis plays an important role in arsenic -induced carcinogenesis. PMID:27876813

  16. XPO1 (CRM1) inhibition represses STAT3 activation to drive a survivin-dependent oncogenic switch in triple-negative breast cancer.

    PubMed

    Cheng, Yan; Holloway, Michael P; Nguyen, Kevin; McCauley, Dilara; Landesman, Yosef; Kauffman, Michael G; Shacham, Sharon; Altura, Rachel A

    2014-03-01

    Inhibition of XPO1 (CRM1)-mediated nuclear export of multiple tumor suppressor proteins has been proposed as a novel cancer therapeutic strategy to turn off oncogenic signals and enhance tumor suppression. Survivin is a multifunctional protein with oncogenic properties when expressed in the cytoplasm that requires the XPO1-RanGTP complex for its nuclear export. We investigated the antitumor mechanisms of the drug-like selective inhibitors of nuclear export (SINE) XPO1 antagonists KPT-185, KPT-251 KPT-276, and KPT-330 in estrogen receptor-positive and triple-negative breast cancer (TNBC) cell lines and xenograft models of human breast tumors. KPT compounds significantly inhibited breast cancer cell growth and induced tumor cell death, both in vitro and in vivo. These drugs initially promoted survivin accumulation within tumor cell nuclei. However, their major in vitro effect was to decrease survivin cytoplasmic protein levels, correlating with the onset of apoptosis. XPO1 inhibition repressed Survivin transcription by inhibiting CREB-binding protein-mediated STAT3 acetylation, and blocking STAT3 binding to the Survivin promoter. In addition, caspase-3 was activated to cleave survivin, rendering it unavailable to bind X-linked inhibitor of apoptosis protein and block the caspase cascade. Collectively, these data demonstrate that XPO1 inhibition by SINE compounds represses STAT3 transactivation to block the selective oncogenic properties of survivin and supports their clinical use in TNBC.

  17. Erythropoietin promotes regeneration of adult CNS neurons via Jak2/Stat3 and PI3K/AKT pathway activation.

    PubMed

    Kretz, Alexandra; Happold, Caroline J; Marticke, Julia K; Isenmann, Stefan

    2005-08-01

    The cytokine hormone erythropoietin (EPO) has proved neuroprotective in CNS injury, and clinical trials for ischemic stroke are ongoing. The capability of EPO to restore postmitotic CNS architecture and function by fibre regeneration has not been examined. Here, we compared in vitro outgrowth capacity of adult retinal ganglion cells (RGCs) following optic nerve (ON) lesion in the presence and absence of EPO. Immediate EPO conditioning in vivo, or delayed EPO treatment of cultures with 10--10,000 IU rhEPO significantly increased numbers (2.66-fold) and length (8.31-fold) of newly generated neurites, without evoking rheological complications. EPO induced Stat3 phosphorylation in RGCs, and inhibition of Jak2/Stat3 abolished EPO-induced growth. EPO-facilitated neuritogenesis was paralleled by upregulation of Bcl-X(L), a Bcl-2 homologue capable of promoting RGC regeneration. The PI3K/Akt pathway was also involved in antiapoptotic and regeneration-enhancing EPO actions. In conclusion, EPO treatment may offer a unique dual-function strategy for neuroprotection and regeneration.

  18. PSM/SH2B1 splice variants: critical role in src catalytic activation and the resulting STAT3s-mediated mitogenic response.

    PubMed

    Zhang, Manchao; Deng, Youping; Riedel, Heimo

    2008-05-01

    A role of PSM/SH2B1 had been shown in mitogenesis and extending to phenotypic cell transformation, however, the underlying molecular mechanism remained to be established. Here, four alternative PSM splice variants and individual functional protein domains were compared for their role in the regulation of Src activity. We found that elevated cellular levels of PSM variants resulted in phenotypic cell transformation and potentiated cell proliferation and survival in response to serum withdrawal. PSM variant activity presented a consistent signature pattern for any tested response of highest activity observed for gamma, followed by delta, alpha, and beta with decreasing activity. PSM-potentiated cell proliferation was sensitive to Src inhibitor herbimycin and PSM and Src were found in the same immune complex. PSM variants were substrates of the Src Tyr kinase and potentiated Src catalytic activity by increasing the V(max) and decreasing the K(m) for ATP with the signature pattern of variant activity. Dominant-negative PSM peptide mimetics including the SH2 or PH domains inhibited Src catalytic activity as well as Src-mediated phenotypic cell transformation. Activation of major Src substrate STAT3 was similarly potentiated by the PSM variants in a Src-dependent fashion or inhibited by PSM domain-specific peptide mimetics. Expression of a dominant-negative STAT3 mutant blocked PSM variant-mediated phenotypic cell transformation. Our results implicate an essential role of the PSM variants in the activation of the Src kinase and the resulting mitogenic response--extending to phenotypic cell transformation and involving the established Src substrate STAT3.

  19. Alternative Roles of STAT3 and MAPK Signaling Pathways in the MMPs Activation and Progression of Lung Injury Induced by Cigarette Smoke Exposure in ACE2 Knockout Mice

    PubMed Central

    Hung, Yi-Han; Hsieh, Wen-Yeh; Hsieh, Jih-Sheng; Liu, Fon-Chang; Tsai, Chin-Hung; Lu, Li-Che; Huang, Chen-Yi; Wu, Chien-Liang; Lin, Chih-Sheng

    2016-01-01

    Inflammation-mediated abnormalities in the renin-angiotensin system (RAS) and expression of matrix metalloproteinases (MMPs) are implicated in the pathogenesis of lung injury. Angiotensin converting enzyme II (ACE2), an angiotensin converting enzyme (ACE) homologue that displays antagonist effects on ACE/angiotensin II (Ang II) axis, could also play a protective role against lung diseases. However, the relationship between ACE2 and MMPs activation in lung injury is still largely unclear. The purpose of this study is to investigate whether MMPs activity could be affected by ACE2 and which ACE2 derived signaling pathways could be also involved via using a mouse model with lung injury induced by cigarette smoke (CS) exposure for 1 to 3 weeks. Wild-type (WT; C57BL/6) and ACE2 KO mice (ACE2-/-) were utilized to study CS-induced lung injury. Increases in the resting respiratory rate (RRR), pulmonary immunokines, leukocyte infiltration and bronchial hyperplasia were observed in the CS-exposed mice. Compared to WT mice, more serious physiopathological changes were found in ACE2-/- mice in the first week of CS exposure. CS exposure increased pulmonary ACE and ACE2 activities in WT mice, and significantly increased ACE in ACE2-/- mice. Furthermore, the activity of pulmonary MMPs was decreased in CS-exposed WT mice, whereas this activity was increased in ACE2-/- mice. CS exposure increased the pulmonary p-p38, p-JNK and p-ERK1/2 level in all mice. In ACE2-/- mice, a significant increase p-STAT3 signaling was detected; however, no effect was observed on the p-STAT3 level in WT mice. Our results support the hypothesis that ACE2 deficiency influences MMPs activation and STAT3 phosphorylation signaling to promote more pulmonary inflammation in the development of lung injury. PMID:27019629

  20. Role of STAT3 in Cancer Metastasis and Translational Advances

    PubMed Central

    Patil, Prachi; Gude, Rajiv P.

    2013-01-01

    Signal transducer and activator of transcription 3 (STAT3) is a latent cytoplasmic transcription factor, originally discovered as a transducer of signal from cell surface receptors to the nucleus. It is activated by tyrosine phosphorylation at position 705 leading to its dimerization, nuclear translocation, DNA binding, and activation of gene transcription. Under normal physiological conditions, STAT3 activation is tightly regulated. However, compelling evidence suggests that STAT3 is constitutively activated in many cancers and plays a pivotal role in tumor growth and metastasis. It regulates cellular proliferation, invasion, migration, and angiogenesis that are critical for cancer metastasis. In this paper, we first describe the mechanism of STAT3 regulation followed by how STAT3 is involved in cancer metastasis, then we summarize the various small molecule inhibitors that inhibit STAT3 signaling. PMID:24199193

  1. AICAR induces astroglial differentiation of neural stem cells via activating the JAK/STAT3 pathway independently of AMP-activated protein kinase.

    PubMed

    Zang, Yi; Yu, Li-Fang; Pang, Tao; Fang, Lei-Ping; Feng, Xu; Wen, Tie-Qiao; Nan, Fa-Jun; Feng, Lin-Yin; Li, Jia

    2008-03-07

    Neural stem cell differentiation and the determination of lineage decision between neuronal and glial fates have important implications in the study of developmental, pathological, and regenerative processes. Although small molecule chemicals with the ability to control neural stem cell fate are considered extremely useful tools in this field, few were reported. AICAR is an adenosine analog and extensively used to activate AMP-activated protein kinase (AMPK), a metabolic "fuel gauge" of the biological system. In the present study, we found an unrecognized astrogliogenic activity of AICAR on not only immortalized neural stem cell line C17.2 (C17.2-NSC), but also primary neural stem cells (NSCs) derived from post-natal (P0) rat hippocampus (P0-NSC) and embryonic day 14 (E14) rat embryonic cortex (E14-NSC). However, another AMPK activator, Metformin, did not alter either the C17.2-NSC or E14-NSC undifferentiated state although both Metformin and AICAR can activate the AMPK pathway in NSC. Furthermore, overexpression of dominant-negative mutants of AMPK in C17.2-NSC was unable to block the gliogenic effects of AICAR. We also found AICAR could activate the Janus kinase (JAK) STAT3 pathway in both C17.2-NSC and E14-NSC but Metformin fails. JAK inhibitor I abolished the gliogenic effects of AICAR. Taken together, these results suggest that the astroglial differentiation effect of AICAR on neural stem cells was acting independently of AMPK and that the JAK-STAT3 pathway is essential for the gliogenic effect of AICAR.

  2. STAT1 and STAT3 in tumorigenesis

    PubMed Central

    Avalle, Lidia; Pensa, Sara; Regis, Gabriella; Novelli, Francesco; Poli, Valeria

    2012-01-01

    The transcription factors STAT1 and STAT3 appear to play opposite roles in tumorigenesis. While STAT3 promotes cell survival/proliferation, motility and immune tolerance and is considered as an oncogene, STAT1 mostly triggers anti-proliferative and pro-apoptotic responses while enhancing anti-tumor immunity. Despite being activated downstream of common cytokine and growth factor receptors, their activation is reciprocally regulated and perturbation in their balanced expression or phosphorylation levels may re-direct cytokine/growth factor signals from proliferative to apoptotic, or from inflammatory to anti-inflammatory. Here we review the functional canonical and non-canonical effects of STAT1 and STAT3 activation in tumorigenesis and their potential cross-regulation mechanisms. PMID:24058752

  3. Downregulated expression of microRNA-124 in pediatric intestinal failure patients modulates macrophages activation by inhibiting STAT3 and AChE

    PubMed Central

    Xiao, Yong-Tao; Wang, Jun; Lu, Wei; Cao, Yi; Cai, Wei

    2016-01-01

    Intestinal inflammation plays a critical role in the pathogenesis of intestinal failure (IF). The macrophages are essential to maintain the intestinal homeostasis. However, the underlying mechanisms of intestinal macrophages activation remain poorly understood. Since microRNAs (miRNAs) have pivotal roles in regulation of immune responses, here we aimed to investigate the role of miR-124 in the activation of intestinal macrophages. In this study, we showed that the intestinal macrophages increased in pediatric IF patients and resulted in the induction of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). The miRNA fluorescence in situ hybridization analysis showed that the expression of miR-124 significantly reduced in intestinal macrophages in IF patients. Overexpression of miR-124 was sufficient to inhibit intestinal macrophages activation by attenuating production of IL-6 and TNF-α. Further studies showed that miR-124 could directly target the 3′-untranslated region of both signal transducer and activator of transcription 3 (STAT3) and acetylcholinesterase (AChE) mRNAs, and suppress their protein expressions. The AChE potentially negates the cholinergic anti-inflammatory signal by hydrolyzing the acetylcholine. We here showed that intestinal macrophages increasingly expressed the AChE and STAT3 in IF patients when compared with controls. The inhibitors against to STAT3 and AChE significantly suppressed the lipopolysaccharides-induced IL-6 and TNF-α production in macrophages. Taken together, these findings highlight an important role for miR-124 in the regulation of intestinal macrophages activation, and suggest a potential application of miR-124 in pediatric IF treatment regarding as suppressing intestinal inflammation. PMID:27977009

  4. Anti-myeloma activity of a multi targeted kinase inhibitor, AT9283, via potent Aurora Kinase and STAT3 inhibition either alone or in combination with lenalidomide

    PubMed Central

    Santo, Loredana; Hideshima, Teru; Cirstea, Diana; Bandi, Madhavi; Nelson, Erik A.; Gorgun, Gullu; Rodig, Scott; Vallet, Sonia; Pozzi, Samantha; Patel, Kishan; Unitt, Christine; Squires, Matt; Hu, Yiguo; Chauhan, Dharminder; Mahindra, Anuj; Munshi, Nikhil C.; Anderson, Kenneth C.; Raje, Noopur

    2014-01-01

    Purpose Aurora Kinases, whose expression is linked to genetic instability and cellular proliferation, are under investigation as novel therapeutic targets in multiple myeloma (MM). Here, we investigated the preclinical activity of a small molecule–multi-targeted kinase inhibitor, AT9283, with potent activity against Aurora kinase A (AURKA), Aurora kinase B (AURKB) and Janus Kinase 2/3. Experimental design We evaluated the in vitro anti myeloma activity of AT9283 alone and in combination with lenalidomide and the in vivo efficacy by using a Xenograft mouse model of human MM. Results Our data demonstrated AT9283 induced cell growth inhibition and apoptosis in MM. Studying the apoptosis mechanism of AT9283 in MM, we observed features consistent with both AURKA and AURKB inhibition, e.g increase of cells with polyploid DNA content, decrease in phospho-Histone H3, and decrease of phospho-Aurora A. Importantly, AT9283 also inhibited STAT3 tyrosine phosphorylation in MM cells. Genetic depletion of STAT3, AURKA or AURKB showed growth inhibition of MM cells, suggesting a role of AT9283-induced inhibition of these molecules in the underlying mechanism of MM cell death. In vivo studies demonstrated decreased MM cell growth and prolonged survival in AT9283-treated mice compared to controls. Importantly, combination studies of AT9283 with lenalidomide showed significant synergistic cytotoxicity in MM cells, even in the presence of bone marrow stromal cells (BMSCs). Enhanced cytotoxicity was associated with increased inhibition of pSTAT3 and pERK. Conclusions Demonstration of in vitro and in vivo anti-MM activity of AT9283 provides the rationale for the clinical evaluation of AT9283 as monotherapy and in combination in patients with MM. PMID:21430070

  5. Activation of the FGFR-STAT3 pathway in breast cancer cells induces a hyaluronan-rich microenvironment that licenses tumor formation.

    PubMed

    Bohrer, Laura R; Chuntova, Pavlina; Bade, Lindsey K; Beadnell, Thomas C; Leon, Ronald P; Brady, Nicholas J; Ryu, Yungil; Goldberg, Jodi E; Schmechel, Stephen C; Koopmeiners, Joseph S; McCarthy, James B; Schwertfeger, Kathryn L

    2014-01-01

    Aberrant activation of fibroblast growth factor receptors (FGFR) contributes to breast cancer growth, progression, and therapeutic resistance. Because of the complex nature of the FGF/FGFR axis, and the numerous effects of FGFR activation on tumor cells and the surrounding microenvironment, the specific mechanisms through which aberrant FGFR activity contributes to breast cancer are not completely understood. We show here that FGFR activation induces accumulation of hyaluronan within the extracellular matrix and that blocking hyaluronan synthesis decreases proliferation, migration, and therapeutic resistance. Furthermore, FGFR-mediated hyaluronan accumulation requires activation of the STAT3 pathway, which regulates expression of hyaluronan synthase 2 (HAS2) and subsequent hyaluronan synthesis. Using a novel in vivo model of FGFR-dependent tumor growth, we demonstrate that STAT3 inhibition decreases both FGFR-driven tumor growth and hyaluronan levels within the tumor. Finally, our results suggest that combinatorial therapies inhibiting both FGFR activity and hyaluronan synthesis is more effective than targeting either pathway alone and may be a relevant therapeutic approach for breast cancers associated with high levels of FGFR activity. In conclusion, these studies indicate a novel targetable mechanism through which FGFR activation in breast cancer cells induces a protumorigenic microenvironment.

  6. Arecoline induces HA22T/VGH hepatoma cells to undergo anoikis - involvement of STAT3 and RhoA activation

    PubMed Central

    2010-01-01

    Background Our previous study showed that, in basal cell carcinoma cells, arecoline reduces levels of the tumor cell survival factor interleukin-6 (IL-6), increases levels of tumor suppressor factor p53, and elicits cell cycle arrest, followed by apoptosis. In preliminarily studies, we observed that arecoline induces detachment of the human-derived hepatoma cell line HA22T/VGH from the extracellular matrix. In the present study, we explored the fate of the detached HA22T/VGH cells and investigated the underlying mechanism. Methods HA22T/VGH cells or primary cultured rat hepatocytes were treated with arecoline, then changes in morphology, viability, apoptosis, and the expression of surface β1-integrin, apoptosis-related proteins, and IL-6 were examined. Furthermore, activation of the signal transducer and activator of transcription 3 (STAT3) pathway and the RhoA/Rock signaling pathway, including p190RhoGAP and Src homology-2 domain-containing phosphatase SHP2, was examined. Results A low concentration of arecoline (≤ 100 μg/ml) caused cytoskeletal changes in HA22T/VGH cells, but not hepatocytes, and this was accompanied by decreased β1-integrin expression and followed by apoptosis, indicating that HA22T/VGH cells undergo anoikis after arecoline treatment. IL-6 expression and phosphorylation of STAT3, which provides protection against anoikis, were inhibited and levels of downstream signaling proteins, including Bcl-XL and Bcl-2, were decreased, while Bax expression, mitochondrial cytochrome c release, and caspase-3 activity were increased. In addition, phosphorylation/activation of p190RhoGAP, a RhoA inhibitor, and of its upstream regulator, SHP2, was inhibited by arecoline treatment, while Rho/Rock activation was increased. Addition of the RhoA inhibitor attenuated the effects of arecoline. Conclusions This study demonstrated that arecoline induces anoikis of HA22T/VGH cells involving inhibition of STAT3 and increased RhoA/Rock activation and that the STAT3

  7. HAVCR/KIM-1 activates the IL-6/STAT-3 pathway in clear cell renal cell carcinoma and determines tumor progression and patient outcome.

    PubMed

    Cuadros, Thaïs; Trilla, Enric; Sarró, Eduard; Vilà, Maya R; Vilardell, Jordi; de Torres, Inés; Salcedo, Mayte; López-Hellin, Joan; Sánchez, Alex; Ramón y Cajal, Santiago; Itarte, Emilio; Morote, Juan; Meseguer, Anna

    2014-03-01

    Renal cell carcinoma (RCC), the third most prevalent urological cancer, claims more than 100,000 lives/year worldwide. The clear cell variant (ccRCC) is the most common and aggressive subtype of this disease. While commonly asymptomatic, more than 30% of ccRCC are diagnosed when already metastatic, resulting in a 95% mortality rate. Notably, nearly one-third of organ-confined cancers treated by nephrectomy develop metastasis during follow-up care. At present, diagnostic and prognostic biomarkers to screen, diagnose, and monitor renal cancers are clearly needed. The gene encoding the cell surface molecule HAVCR1/KIM-1 is a suggested susceptibility gene for ccRCC and ectodomain shedding of this molecule may be a predictive biomarker of tumor progression. Microarray analysis of 769-P ccRCC-derived cells where HAVCR/KIM-1 levels have been upregulated or silenced revealed relevant HAVCR/KIM-1-related targets, some of which were further analyzed in a cohort of 98 ccRCC patients with 100 month follow-up. We found that HAVCR/KIM-1 activates the IL-6/STAT-3/HIF-1A axis in ccRCC-derived cell lines, which depends on HAVCR/KIM-1 shedding. Moreover, we found that pSTAT-3 S727 levels represented an independent prognostic factor for ccRCC patients. Our results suggest that HAVCR/KIM-1 upregulation in tumors might represent a novel mechanism to activate tumor growth and angiogenesis and that pSTAT-3 S727 is an independent prognostic factor for ccRCC.

  8. AZD9150, a Next-Generation Antisense Oligonucleotide Inhibitor of STAT3 with Early Evidence of Clinical Activity in Lymphoma and Lung Cancer

    PubMed Central

    Hong, David; Kurzrock, Razelle; Kim, Youngsoo; Woessner, Richard; Younes, Anas; Nemunaitis, John; Fowler, Nathan; Zhou, Tianyuan; Schmidt, Joanna; Jo, Minji; Lee, Samantha J.; Yamashita, Mason; Hughes, Steven G.; Fayad, Luis; Piha-Paul, Sarina; Nadella, Murali VP; Mohseni, Morvarid; Lawson, Deborah; Reimer, Corinne; Blakey, David C.; Xiao, Xiaokun; Hsu, Jeff; Revenko, Alexey; Monia, Brett P.; MacLeod, A. Robert

    2017-01-01

    Next-generation sequencing technologies have greatly expanded our understanding of cancer genetics. Antisense technology is an attractive platform with the potential to translate these advances into improved cancer therapeutics, because antisense oligonucleotide (ASO) inhibitors can be designed on the basis of gene sequence information alone. Recent human clinical data have demonstrated the potent activity of systemically administered ASOs targeted to genes expressed in the liver. Here, we describe the preclinical activity and initial clinical evaluation of a class of ASOs containing constrained ethyl modifications for targeting the gene encoding the transcription factor STAT3, a notoriously difficult protein to inhibit therapeutically. Systemic delivery of the unformulated ASO, AZD9150, decreased STAT3 expression in a broad range of preclinical cancer models and showed antitumor activity in lymphoma and lung cancer models. AZD9150 preclinical activity translated into single-agent antitumor activity in patients with highly treatment-refractory lymphoma and non-small cell lung cancer in a phase I dose escalation study. PMID:26582900

  9. Targeting STAT3 in cancer: how successful are we?

    PubMed Central

    Yue, Peibin; Turkson, James

    2008-01-01

    Background Aberrant activation of the signal transducer and activator of transcription (STAT)3 occurs in many human tumors. Moreover, studies utilizing genetic and pharmacological approaches to modulate constitutive STAT3 activity have provided compelling evidence for the critical role of aberrant STAT3 activity in malignant transformation and tumor progression, and thereby validated STAT3 as a novel cancer drug target. Objective This review is intended to be a full coverage of the efforts to develop direct STAT3 inhibitors and will provide a discussion on the inhibitory modalities developed to date. Methods Review of the literature focused on the modalities and mechanisms that directly target and inhibit the STAT protein or its functions. Results/conclusion While a variety of STAT3 inhibitors have been identified that induce antitumor cell effects in vitro and in vivo, the landscape remains murky. With a few exceptions, most of the STAT3 inhibitors reported to date have not undergone an in vivo efficacy, pharmacology or toxicity testing. Also, there is no evidence, per the published literature of an impending clinical development for the few agents that were reported to exhibit in vivo efficacy. Overall, there is the need for a reassessment of the ongoing strategies to target STAT3 intended not only for refinement, but also for incorporating some new technologies to strengthen our efforts and ensure the success – sooner, rather than later – of identifying suitable anti-STAT3 agents for development into clinically useful anticancer therapeutics. PMID:19053881

  10. Protein kinase CK2 regulates AKT, NF-κB and STAT3 activation, stem cell viability and proliferation in acute myeloid leukemia.

    PubMed

    Quotti Tubi, L; Canovas Nunes, S; Brancalion, A; Doriguzzi Breatta, E; Manni, S; Mandato, E; Zaffino, F; Macaccaro, P; Carrino, M; Gianesin, K; Trentin, L; Binotto, G; Zambello, R; Semenzato, G; Gurrieri, C; Piazza, F

    2017-02-01

    Protein kinase CK2 sustains acute myeloid leukemia cell growth, but its role in leukemia stem cells is largely unknown. Here, we discovered that the CK2 catalytic α and regulatory β subunits are consistently expressed in leukemia stem cells isolated from acute myeloid leukemia patients and cell lines. CK2 inactivation with the selective inhibitor CX-4945 or RNA interference induced an accumulation of leukemia stem cells in the late S-G2-M phases of the cell cycle and triggered late-onset apoptosis. As a result, leukemia stem cells displayed an increased sensitivity to the chemotherapeutic agent doxorubicin. From a molecular standpoint, CK2 blockade was associated with a downmodulation of the stem cell-regulating protein BMI-1 and a marked impairment of AKT, nuclear factor-κB (NF-κB) and signal transducer and activator of transcription 3 (STAT3) activation, whereas FOXO3a nuclear activity was induced. Notably, combined CK2 and either NF-κB or STAT3 inhibition resulted in a superior cytotoxic effect on leukemia stem cells. This study suggests that CK2 blockade could be a rational approach to minimize the persistence of residual leukemia cells.

  11. Cannabinoid receptor CB1 regulates STAT3 activity and its expression dictates the responsiveness to SR141716 treatment in human glioma patients' cells

    PubMed Central

    Ciaglia, Elena; Torelli, Giovanni; Pisanti, Simona; Picardi, Paola; D'Alessandro, Alba; Laezza, Chiara; Malfitano, Anna Maria; Fiore, Donatella; Zottola, Antonio Christian Pagano; Proto, Maria Chiara; Catapano, Giuseppe; Gazzerro, Patrizia; Bifulco, Maurizio

    2015-01-01

    Herein we show that a majority of human brain tumor samples and cell lines over-expressed cannabinoid receptor CB1 as compared to normal human astrocytes (NHA), while uniformly expressed low levels of CB2. This finding prompted us to investigate the therapeutic exploitation of CB1 inactivation by SR141716 treatment, with regard to its direct and indirect cell-mediated effects against gliomas. Functional studies, using U251MG glioma cells and primary tumor cell lines derived from glioma patients expressing different levels of CB1, highlighted SR141716 efficacy in inducing apoptosis via G1 phase stasis and block of TGF-β1 secretion through a mechanism that involves STAT3 inhibition. According to the multivariate role of STAT3 in the immune escape too, interestingly SR141716 lead also to the functional and selective expression of MICA/B on the surface of responsive malignant glioma cells, but not on NHA. This makes SR141716 treated-glioma cells potent targets for allogeneic NK cell-mediated recognition through a NKG2D restricted mechanism, thus priming them for NK cell antitumor reactivity. These results indicate that CB1 and STAT3 participate in a new oncogenic network in the complex biology of glioma and their expression levels in patients dictate the efficacy of the CB1 antagonist SR141716 in multimodal glioma destruction. SIGNIFICANCE CB1 is implicated in the regulation of cellular processes linked to survival, proliferation, invasion and angiogenesis in several physio-pathological conditions. We shed light on previously unrecognized molecular mechanism of CB1-mediated modulation of human glioma progression and provide the first and original demonstration of CB1-STAT3 axis as a new target and predictor biomarkers of the benefit from specific therapies. Indeed CB1 antagonism capable of tumoral cell division' control while making the glioma immunovisible and engaging the immune system to fight it may represent a hopeful alternative to other established

  12. Inhibition of STAT3 by Anticancer Drug Bendamustine

    PubMed Central

    Iwamoto, Kazunori; Uehara, Yutaka; Inoue, Yukie; Taguchi, Kyoko; Muraoka, Daisuke; Ogo, Naohisa; Matsuno, Kenji; Asai, Akira

    2017-01-01

    Bendamustine (BENDA), which bears the bis(2-chloroethyl)amino moiety, is an alkylating agent that stops the growth of cancer cells by binding to DNA and interfering with its replication. However, the mechanism of action underlying its excellent clinical efficacy remains unclear. In this work, we report that BENDA inhibits signal transducer and activator of transcription 3 (STAT3). In an AlphaScreen-based biochemical assay using recombinant human STAT3, binding of STAT3–Src homology 2 (SH2) to the phosphotyrosine (pTyr, pY) peptide was inhibited by BENDA but not by the inactive metabolite dihydroxy bendamustine (HP2). When a single point mutation of C550A or C712A was introduced into recombinant human STAT3, its sensitivity to BENDA was substantially reduced, suggesting that these cysteine residues are important for BENDA to inhibit STAT3. Furthermore, BENDA suppressed the function of cellular STAT3 as a transcriptional activator in a human breast cancer cell line, MDA-MB-468, with constitutively activated STAT3. A competitive pull-down assay using biotinylated BENDA (Bio-BENDA) revealed that BENDA bound tightly to cellular STAT3, presumably through covalent bonds. Therefore, our results suggest that the anticancer effects of BENDA may be associated, at least in part, with its inhibitory effect on the SH2 domain of STAT3. PMID:28125678

  13. The mitochondrial-derived peptide humanin activates the ERK1/2, AKT, and STAT3 signaling pathways and has age-dependent signaling differences in the hippocampus.

    PubMed

    Kim, Su-Jeong; Guerrero, Noel; Wassef, Gabriella; Xiao, Jialin; Mehta, Hemal H; Cohen, Pinchas; Yen, Kelvin

    2016-07-26

    Humanin is a small secreted peptide that is encoded in the mitochondrial genome. Humanin and its analogues have a protective role in multiple age-related diseases including type 2 diabetes and Alzheimer's disease, through cytoprotective and neuroprotective effects both in vitro and in vivo. However, the humanin-mediated signaling pathways are not well understood. In this paper, we demonstrate that humanin acts through the GP130/IL6ST receptor complex to activate AKT, ERK1/2, and STAT3 signaling pathways. Humanin treatment increases phosphorylation in AKT, ERK 1/2, and STAT3 where PI3K, MEK, and JAK are involved in the activation of those three signaling pathways, respectively. Furthermore, old mice, but not young mice, injected with humanin showed an increase in phosphorylation in AKT and ERK1/2 in the hippocampus. These findings uncover a key signaling pathway of humanin that is important for humanin's function and also demonstrates an age-specific in vivo effect in a region of the brain that is critical for memory formation in an age-dependent manner.

  14. Pyranocoumarins isolated from Peucedanum praeruptorum Dunn suppress lipopolysaccharide-induced inflammatory response in murine macrophages through inhibition of NF-κB and STAT3 activation.

    PubMed

    Yu, Peng-Jiu; Jin, Hong; Zhang, Jun-Yan; Wang, Guang-Fa; Li, Jing-Rong; Zhu, Zheng-Guang; Tian, Yuan-Xin; Wu, Shao-Yu; Xu, Wei; Zhang, Jia-Jie; Wu, Shu-Guang

    2012-06-01

    Praeruptorin C, D, and E (PC, PD, and PE) are three pyranocoumarins isolated from the dried root of Peucedanum praeruptorum Dunn of Umbelliferae. In the present study, we investigated the anti-inflammatory effect of these compounds in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells. Pyranocoumarins significantly inhibited LPS-induced production of nitric oxide, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). The mRNA and protein expressions of inducible nitric oxide synthase, IL-6, and TNF-α were also suppressed by these compounds. Both PD and PE exhibited greater anti-inflammatory activities than PC. Further study showed that pyranocoumarins suppressed the cytoplasmic loss of inhibitor κB-α protein and inhibited the translocation of NF-κB from cytoplasm to nucleus. In addition, pyranocoumarins suppressed LPS-induced STAT3 tyrosine phosphorylation. Taken together, the results suggest that pyranocoumarins may exert anti-inflammatory effects in LPS-stimulated RAW 264.7 macrophages through the inhibition of NF-κB and STAT3 activation.

  15. CD147 promotes Src-dependent activation of Rac1 signaling through STAT3/DOCK8 during the motility of hepatocellular carcinoma cells

    PubMed Central

    Zhao, Pu; Zhang, Yang; Fu, Zhi-Guang; Chen, Zhi-Nan; Jiang, Jian-Li

    2015-01-01

    Metastasis is considered a dynamic process in tumor development that is related to abnormal migration and invasion. Tumor cells can move as individual cells in two interconvertible modes: mesenchymal-type and amoeboid. Previously, we reported that the interaction between CD147 and Annexin II can inhibit the amoeboid movement in hepatocellular carcinoma (HCC) cells. However, the mechanism of CD147 involved in mesenchymal movement is still unclear. Notably, our results show overexpression of CD147 led to mesenchymal-type movement in HCC cells. Evidence indicated that the mesenchymal-type cell movement induced by CD147 was Src dependent, as observed by confocal microscopy and Rac1 activity assay. The phosphorylation of Src (pY416-Src) can be up-regulated by CD147, and this regulation is mediated by focal adhesion kinase (FAK). Next, we identified DOCK8 as a GEF for Rac1, a key molecule driving mesenchymal-type movement. We also found that Src promotes STAT3 phosphorylation and STAT3 facilitates DOCK8 transcription, thus enhancing DOCK8 expression and Rac1 activation. This study provides a novel mechanism of CD147 regulating mesenchymal-type movement in HCC cells. PMID:25428919

  16. CD147 promotes Src-dependent activation of Rac1 signaling through STAT3/DOCK8 during the motility of hepatocellular carcinoma cells.

    PubMed

    Wang, Shi-Jie; Cui, Hong-Yong; Liu, Yan-Mei; Zhao, Pu; Zhang, Yang; Fu, Zhi-Guang; Chen, Zhi-Nan; Jiang, Jian-Li

    2015-01-01

    Metastasis is considered a dynamic process in tumor development that is related to abnormal migration and invasion. Tumor cells can move as individual cells in two interconvertible modes: mesenchymal-type and amoeboid. Previously, we reported that the interaction between CD147 and Annexin II can inhibit the amoeboid movement in hepatocellular carcinoma (HCC) cells. However, the mechanism of CD147 involved in mesenchymal movement is still unclear. Notably, our results show overexpression of CD147 led to mesenchymal-type movement in HCC cells. Evidence indicated that the mesenchymal-type cell movement induced by CD147 was Src dependent, as observed by confocal microscopy and Rac1 activity assay. The phosphorylation of Src (pY416-Src) can be up-regulated by CD147, and this regulation is mediated by focal adhesion kinase (FAK). Next, we identified DOCK8 as a GEF for Rac1, a key molecule driving mesenchymal-type movement. We also found that Src promotes STAT3 phosphorylation and STAT3 facilitates DOCK8 transcription, thus enhancing DOCK8 expression and Rac1 activation. This study provides a novel mechanism of CD147 regulating mesenchymal-type movement in HCC cells.

  17. Elevated level of Interleukin-35 in colorectal cancer induces conversion of T cells into iTr35 by activating STAT1/STAT3

    PubMed Central

    Xie, Guohua; Zhou, Yunlan; Yue, Chaoyan; Yuan, Xiangliang; Zheng, Yingxia; Wang, Weiwei; Deng, Lin; Shen, Lisong

    2016-01-01

    IL-35 is a novel heterodimeric and inhibitory cytokine, composed of interleukin-12 subunit alpha (P35) and Epstein-Barr virus -induced gene 3 (EBI3). IL-35 has been reported to be produced by a range of cell types, especially regulatory T cells, and to exert immunosuppressive effects via the STATx signaling pathway. In this study, we demonstrated that IL-35 expression was elevated in both serum and tumors in patients with colorectal cancer. IL-35 mainly expressed in CD4+ T cells in human colorectal cancer tumors and adjacent tissues. Increased IL-35 expression in tumor-adjacent tissues was significantly associated with tumor metastasis. IL-35 inhibited the proliferation of CD4+CD25− T effector cells in vitro in a dose-dependent manner, and its suppression was partially reversed by applying IL-35-neutralizing antibodies. IL-35 treatment activated the phosphorylation of both STAT1 and STAT3 in human CD4+ T cells. Meanwhile, IL-35 induced a positive feedback loop to promote its own production. We observed that Tregs obtained from colorectal cancer patients were capable of inducing more IL-35 production. In addition, EBI3 promoter-driven luciferase activity was higher than that of the mock plasmid after IL-35stimulation. Thus, our study indicates that the high level of IL-35 in colorectal cancer promotes the production of IL-35 via STAT1 and STAT3, which suppresses T cell proliferation and may participate in tumor immunotolerance. PMID:27682874

  18. The mitochondrial-derived peptide humanin activates the ERK1/2, AKT, and STAT3 signaling pathways and has age-dependent signaling differences in the hippocampus

    PubMed Central

    Kim, Su-Jeong; Guerrero, Noel; Wassef, Gabriella; Xiao, Jialin; Mehta, Hemal H.; Cohen, Pinchas; Yen, Kelvin

    2016-01-01

    Humanin is a small secreted peptide that is encoded in the mitochondrial genome. Humanin and its analogues have a protective role in multiple age-related diseases including type 2 diabetes and Alzheimer's disease, through cytoprotective and neuroprotective effects both in vitro and in vivo. However, the humanin-mediated signaling pathways are not well understood. In this paper, we demonstrate that humanin acts through the GP130/IL6ST receptor complex to activate AKT, ERK1/2, and STAT3 signaling pathways. Humanin treatment increases phosphorylation in AKT, ERK 1/2, and STAT3 where PI3K, MEK, and JAK are involved in the activation of those three signaling pathways, respectively. Furthermore, old mice, but not young mice, injected with humanin showed an increase in phosphorylation in AKT and ERK1/2 in the hippocampus. These findings uncover a key signaling pathway of humanin that is important for humanin's function and also demonstrates an age-specific in vivo effect in a region of the brain that is critical for memory formation in an age-dependent manner. PMID:27384491

  19. Discovery of Potent Anticancer Agent HJC0416, an Orally Bioavailable Small Molecule Inhibitor of Signal Transducer and Activator of Transcription 3 (STAT3)

    PubMed Central

    Chen, Haijun; Yang, Zhengduo; Ding, Chunyong; Xiong, Ailian; Wild, Christopher; Wang, Lili; Ye, Na; Cai, Guoshuai; Flores, Rudolfo M.; Ding, Ye; Shen, Qiang; Zhou, Jia

    2014-01-01

    In a continuing effort to develop orally bioavailable small-molecule STAT3 inhibitors as potential therapeutic agents for human cancer, a series of novel diversified analogues based on our identified lead compound HJC0149 (1) (5-chloro-N-(1,1-dioxo-1H-1λ6-benzo[b]thiophen-6-yl)-2-hydroxybenzamide, Eur. J. Med. Chem. 2013, 62, 498–507) have been rationally designed, synthesized, and pharmacologically evaluated. Molecular docking studies and biological characterization supported our earlier findings that the O-alkylamino-tethered side chain on the hydroxyl group is an effective and essential structural determinant for improving biological activities and druglike properties of these molecules. Compounds with such modifications exhibited potent antiproliferative effects against breast and pancreatic cancer cell lines with IC50 values from low micromolar to nanomolar range. Among them, the newly discovered STAT3 inhibitor 12 (HJC0416) displayed an intriguing anticancer profile both in vitro and in vivo (i.p. & p.o.). More importantly, HJC0416 is an orally bioavailable anticancer agent as a promising candidate for further development. PMID:24904966

  20. The ROS-mediated activation of STAT-3/VEGF signaling is involved in the 27-hydroxycholesterol-induced angiogenesis in human breast cancer cells.

    PubMed

    Zhu, Dongmei; Shen, Zhaoxia; Liu, Jiao; Chen, Juan; Liu, Yun; Hu, Chunyan; Li, Zhong; Li, Yuan

    2016-12-15

    Breast cancer (BC) is the leading cause of cancer-related mortality among females worldwide, and angiogenesis plays a crucial role in BC progression. 27-Hydroxycholesterol (27HC) is an endogenous selective estrogen receptor modulator, which promotes the growth and metastasis of BC. Here, we further found that, 27HC improved the angiogenic ability of BC in a VEGF-dependent manner. For the molecular mechanisms, on one hand, as an estrogen-like factor, 27HC enhanced the expression of VEGF by the classical ERα/VEGF signaling in ER-positive BC cells; on the other hand, in both ER-positive and ER-negative BC cells, 27HC enhanced the generation of ROS, which in turn activated the STAT-3/VEGF signaling in an ER independent manner. Either blocking the generation of ROS or knockdown of STAT-3 attenuated the 27HC-induced autocrine of VEGF and angiogenesis. These findings not only suggested a mechanism whereby 27HC enhanced the angiogenesis, but also helped to recognize the 27HC as a novel potential harmful factor in BC, especially in the menopause patients.

  1. 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 STAT3β, 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

  2. p-21 activated kinase 4 (PAK4) maintains stem cell-like phenotypes in pancreatic cancer cells through activation of STAT3 signaling

    PubMed Central

    Tyagi, Nikhil; Marimuthu, Saravanakumar; Bhardwaj, Arun; Deshmukh, Sachin K.; Srivastava, Sanjeev K.; Singh, Ajay P.; McClellan, Steven; Carter, James E.; Singh, Seema

    2015-01-01

    Pancreatic cancer (PC) remains a highly lethal malignancy due to its unusual chemoresistance and high aggressiveness. A subpopulation of pancreatic tumor cells, known as cancer stem cells (CSCs), is considered responsible not only for tumor-maintenance, but also for its widespread metastasis and therapeutic failure. Here we investigated the role of p-21 activated kinase 4 (PAK4) in driving PC stemness properties. Our data demonstrate that triple-positive (CD24+/CD44+/EpCAM+) subpopulation of pancreatic CSCs exhibits greater level of PAK4 as compared to triple-negative (CD24−/CD44−/EpCAM−) cells. Moreover, PAK4 silencing in PC cells leads to diminished fraction of CD24, CD44, and EpCAM positive cells. Furthermore, we show that PAK4-silenced PC cells exhibit decreased sphere-forming ability and increased chemo-sensitivity to gemcitabine toxicity. PAK4 expression is also associated with enhanced levels of stemness-associated transcription factors (Oct4/Nanog/Sox2 and KLF4). Furthermore, our data show decreased nuclear accumulation and transcriptional activity of STAT3 in PAK4-silenced PC cells and restitution of its activity leads to restoration of stem cell phenotypes. Together, our findings deliver first experimental evidence for the involvement of PAK4 in PC stemness and support its clinical utility as a novel therapeutic target in PC. PMID:26546043

  3. Targeting cancer initiating cells by promoting cell differentiation and restoring chemosensitivity via dual inactivation of STAT3 and Src activity using an active component of Antrodia cinnamomea mycelia

    PubMed Central

    Chan, Ik-On; Chen, Chin-Chu; Sheu, Sen-Je; Lin, Ting-wei; Chou, Shiu-Huey; Liu, Chung-Ji; Lee, Te-Chang; Lo, Jeng-Fan

    2016-01-01

    Cancer initiating cells (CICs) represent a subpopulation of cancer cells, which are responsible for tumor growth and resistance to chemotherapy. Herein, we first used a cell-based aldehyde dehydrogenase (ALDH) activity assay to identify that YMGKI-2 (also named as Ergone), an active component purified from Antrodia cinnamomea Mycelia extract (ACME), effectively abrogated the ALDH activity and abolished the CICs in head and neck squamous cell carcinoma cells (HNSCCs). Consequently, YMGKI-2 treatment suppressed self-renewal ability and expression of stemness signature genes (Oct-4 and Nanog) of sphere cells with enriched CICs. Moreover, YMGKI-2 treated sphere cells displayed reduction of CICs properties and promotion of cell differentiation, but not significant cytotoxicity. YMGKI-2 treatment also attenuated the tumorigenicity of HNSCC cells in vivo. Mechanistically, treatment of YMGKI-2 resulted in inactivation of STAT3 and Src. Lastly, combinatorial treatments with YMGKI-2 and standard chemotherapeutic drugs (cisplatin or Fluorouracil) restored the chemosensivity on sphere cells and cisplatin-resistant HNSCC cells. Together, we demonstrate that YMGKI-2 treatment effectively induces differentiation and reduces tumorigenicity of CICs. Further, combined treatment of YMGKI-2 and conventional chemotherapy can overcome chemoresistance. These results suggest that YMGKI-2 treatment may be used to improve future clinical responses in head and neck cancer treatment through targeting CICs. PMID:27682875

  4. Constitutive Phosphorylation of STAT3 by the CK2-BLNK-CD5 Complex.

    PubMed

    Rozovski, Uri; Harris, David M; Li, Ping; Liu, Zhiming; Jain, Preetesh; Veletic, Ivo; Ferrajoli, Alessandra; Burger, Jan; O'Brien, Susan; Bose, Prithviraj; Thompson, Philip; Jain, Nitin; Wierda, William; Keating, Michael J; Estrov, Zeev

    2017-01-27

    In chronic lymphocytic leukemia (CLL), STAT3 is constitutively phosphorylated on serine 727 and plays a role in the pathobiology of CLL. However, what induces constitutive phosphorylation of STAT3 is currently unknown. Mass spectrometry was used to identify casein kinase 2 (CK2), a serine/threonine kinase that co-immunoprecipitated with serine phosphorylated STAT3 (pSTAT3). Furthermore, activated CK2 incubated with recombinant STAT3 induced phosphorylation of STAT3 on serine 727. Although STAT3 and CK2 are present in normal B- and T-cells, STAT3 is not constitutively phosphorylated in these cells. Further study found that CD5 and BLNK co-expressed in CLL, but not in normal B- or T-cells, are required for STAT3 phosphorylation. To elucidate the relationship of CD5 and BLNK to CK2 and STAT3, STAT3 was immunoprecipitated from CLL cells and CK2, CD5, and BLNK were detected in the immunoprecipitate. Conversely, STAT3, CD5, and BLNK were in the immunoprecipitate of CLL cells immunoprecipitated with CK2 antibodies. Furthermore, siRNA knockdown of CD5 or BLNK, or treatment with CD5-neutralizing antibodies significantly reduced the levels of serine pSTAT3 in CLL cells. Finally, confocal microscopy determined that CD5 is cell membrane bound and fractionation studies revealed that the CK2/CD5/BLNK/STAT3 complex remains in the cytoplasm, whereas serine pSTAT3 is shuttled to the nucleus.

  5. Inorganic Phosphate Prevents Erk1/2 and Stat3 Activation and Improves Sensitivity to Doxorubicin of MDA-MB-231 Breast Cancer Cells.

    PubMed

    Sapio, Luigi; Sorvillo, Luca; Illiano, Michela; Chiosi, Emilio; Spina, Annamaria; Naviglio, Silvio

    2015-09-01

    Due to its expression profile, triple-negative breast cancer (TNBC) is refractory to the most effective targeted therapies available for breast cancer treatment. Thus, cytotoxic chemotherapy represents the mainstay of treatment for early and metastatic TNBC. Therefore, it would be greatly beneficial to develop therapeutic approaches that cause TNBC cells to increase their sensitivity to cytotoxic drugs. Inorganic phosphate (Pi) is emerging as an important signaling molecule in many cell types. Interestingly, it has been shown that Pi greatly enhances the sensitivity of human osteosarcoma cell line (U2OS) to doxorubicin. We investigated the effects of Pi on the sensitivity of TNBC cells to doxorubicin and the underlying molecular mechanisms, carrying out flow cytometry-based assays of cell-cycle progression and cell death, MTT assays, direct cell number counting and immunoblotting experiments. We report that Pi inhibits the proliferation of triple-negative MDA-MB-231 breast cancer cells mainly by slowing down cell cycle progression. Interestingly, we found that Pi strongly increases doxorubicin-induced cytotoxicity in MDA-MB-231 cells by apoptosis induction, as revealed by a marked increase of sub-G1 population, Bcl-2 downregulation, caspase-3 activation and PARP cleavage. Remarkably, Pi/doxorubicin combination-induced cytotoxicity was dynamically accompanied by profound changes in Erk1/2 and Stat3 protein and phosphorylation levels. Altogether, our data enforce the evidence of Pi acting as a signaling molecule in MDA-MB-231 cells, capable of inhibiting Erk and Stat3 pathways and inducing sensitization to doxorubicin of TNBC cells, and suggest that targeting Pi levels at local sites might represent the rationale for developing effective and inexpensive strategies for improving triple-negative breast cancer therapy.

  6. Role of STAT3 pathway in genitourinary tumors

    PubMed Central

    Santoni, Matteo; Conti, Alessandro; Piva, Francesco; Massari, Francesco; Ciccarese, Chiara; Burattini, Luciano; Cheng, Liang; Lopez-Beltran, Antonio; Scarpelli, Marina; Santini, Daniele; Tortora, Giampaolo; Cascinu, Stefano; Montironi, Rodolfo

    2015-01-01

    The STAT3 is often dysregulated in genitourinary tumors. In prostate cancer, STAT3 activation correlates with Gleason score and pathological stage and modulates cancer stem cells and epithelial–mesenchymal transition. In addition, STAT3 promotes the progression from carcinoma in situ to invasive bladder cancer and modulates renal cell carcinoma angiogenesis by increasing the expression of HIF1α and VEGF. STAT3 is also involved in the response to tyrosine kinase inhibitors sunitinib and axitinib, in patients with metastatic renal cell carcinoma, and to second-generation androgen receptor inhibitor enzalutamide in patients with advanced prostate cancer. In this review, we describe the role of STAT3 in genitourinary tumors, thus describing its potential for future therapeutic strategies. PMID:28031890

  7. Design, Synthesis and in vitro Characterization of Novel Hybrid Peptidomimetic Inhibitors of STAT3 Protein

    PubMed Central

    Shahani, Vijay M.; Yue, Peibin; Fletcher, Steven; Sharmeen, Sumaiya; Sukhai, Mahadeo A.; Luu, Diana P.; Zhang, Xiaolei; Sun, Hong; Zhao, Wei; Schimmer, Aaron D.; Turkson, James; Gunning, Patrick T.

    2011-01-01

    Aberrant activation of oncogenic signal transducer and activator of transcription 3 (STAT3) protein signaling pathways has been extensively implicated in human cancers. Given STAT3’s prominent dysregulatory role in malignant transformation and tumorigenesis, there has been a significant effort to discover STAT3-specific inhibitors as chemical probes for defining the aberrant STAT3-mediated molecular events that support the malignant phenotype. To identify novel, STAT3-selective inhibitors suitable for interrogating STAT3 signaling in tumor cells, we explored the design of hybrid molecules by conjugating a known STAT3 inhibitory peptidomimetic, ISS610 to the high-affinity STAT3-binding peptide motif derived from the ILR/gp-130. Several hybrid molecules were examined in in vitro biophysical and biochemical studies for inhibitory potency against STAT3. Lead inhibitor 14aa was shown to strongly bind to STAT3 (KD = 900 nM), disrupt STAT3:phosphopeptide complexes (Ki = 5 μM) and suppress STAT3 activity in in vitro DNA-binding activity/ electrophoretic mobility shift assay (EMSA). Moreover, lead STAT3 inhibitor 14aa induced a time-dependent inhibition of constitutive STAT3 activation in v-Src transformed mouse fibroblasts (NIH3T3/v-Src), with 80 % suppression of constitutively-active STAT3 at six hours following treatment of NIH3T3/v-Src. However, STAT3 activity recovered at 24 hours after treatment of cells, suggesting potential degradation of the compound. Results further showed a suppression of aberrant STAT3 activity in NIH3T3/v-Src by the treatment with compound 14aa-OH, which is the non-pTyr version of compound 14aa. The effect of compounds 14aa and 14aa-OH are accompanied by a moderate loss of cell viability. PMID:21216604

  8. Suppression by Δ(9)-tetrahydrocannabinol of the primary immunoglobulin M response by human peripheral blood B cells is associated with impaired STAT3 activation.

    PubMed

    Ngaotepprutaram, Thitirat; Kaplan, Barbara L F; Carney, Stephen; Crawford, Robert; Kaminski, Norbert E

    2013-08-09

    This study was undertaken to gain insights into the mechanism for Δ(9)-tetrahydrocannabinol (Δ(9)-THC)-mediated suppression of primary immunoglobulin M (IgM) responses in humans. An in vitro activation model, which employs cell surface-expressed CD40 ligand (CD40L) and recombinant cytokines (interleukin (IL)-2, -6, and -10), was used to differentiate human peripheral blood (HPB) naïve B cells into IgM secreting cells. Pretreatment with Δ(9)-THC significantly decreased the number of IgM secreting cells as determined by ELISPOT. The attenuation of IgM secretion by Δ(9)-THC involved, at least in part, the impairment of plasma cell differentiation as evidenced by suppression of immunoglobulin joining chain (IgJ) mRNA expression. The analysis at each of two different stages critically involved in plasma cell differentiation indicates that Δ(9)-THC impaired both the primary activation stage and proliferation of B cells. Interestingly, Δ(9)-THC selectively suppressed the surface expression of CD80, but not other measured B-cell activation markers (CD69, CD86, and ICAM1). Furthermore, pretreatment with Δ(9)-THC was accompanied by a robust decrease of STAT3 phosphorylation, whereas the phosphorylation of the p65 NFκB subunit was not affected. Collectively, these data provide new insights into the mechanisms for impaired B cell function by Δ(9)-THC.

  9. STAT3 upregulation in pituitary somatotroph adenomas induces growth hormone hypersecretion.

    PubMed

    Zhou, Cuiqi; Jiao, Yonghui; Wang, Renzhi; Ren, Song-Guang; Wawrowsky, Kolja; Melmed, Shlomo

    2015-04-01

    Pituitary somatotroph adenomas result in dysregulated growth hormone (GH) hypersecretion and acromegaly; however, regulatory mechanisms that promote GH hypersecretion remain elusive. Here, we provide evidence that STAT3 directly induces somatotroph tumor cell GH. Evaluation of pituitary tumors revealed that STAT3 expression was enhanced in human GH-secreting adenomas compared with that in nonsecreting pituitary tumors. Moreover, STAT3 and GH expression were concordant in a somatotroph adenoma tissue array. Promoter and expression analysis in a GH-secreting rat cell line (GH3) revealed that STAT3 specifically binds the Gh promoter and induces transcription. Stable expression of STAT3 in GH3 cells induced expression of endogenous GH, and expression of a constitutively active STAT3 further enhanced GH production. Conversely, expression of dominant-negative STAT3 abrogated GH expression. In primary human somatotroph adenoma-derived cell cultures, STAT3 suppression with the specific inhibitor S3I-201 attenuated GH transcription and reduced GH secretion in the majority of derivative cultures. In addition, S3I-201 attenuated somatotroph tumor growth and GH secretion in a rat xenograft model. GH induced STAT3 phosphorylation and nuclear translocation, indicating a positive feedback loop between STAT3 and GH in somatotroph tumor cells. Together, these results indicate that adenoma GH hypersecretion is the result of STAT3-dependent GH induction, which in turn promotes STAT3 expression, and suggest STAT3 as a potential therapeutic target for pituitary somatotroph adenomas.

  10. The antihistamines clemastine and desloratadine inhibit STAT3 and c-Myc activities and induce apoptosis in cutaneous T-cell lymphoma cell lines.

    PubMed

    Döbbeling, Udo; Waeckerle-Men, Ying; Zabel, Franziska; Graf, Nicole; Kündig, Thomas M; Johansen, Pål

    2013-02-01

    Mycosis fungoides and its leukaemic counterpart Sézary syndrome are the most frequent cutaneous T-cell lymphomas (CTCL), and there is no cure for these diseases. We evaluated the effect of clinically approved antihistamines on the growth of CTCL cell lines. CTCL cell lines as well as blood lymphocytes from patients with Sézary syndrome were cultured with antihistamines, and the cell were analysed for proliferation, apoptosis and expression of programmed death molecules and transcription factors. The two antihistamines clemastine and desloratadine, currently used for symptom alleviation in allergy, induced potent reduction of the activities of the constitutively active transcription factors c-Myc, STAT3, STAT5a and STAT5b in mycosis fungoides and Sézary syndrome cell lines. This inhibition was followed by apoptosis and cell death, especially in the Sézary syndrome-derived cell line Hut78 that also showed increased expression of the programmed death-1 (PD-1) after clemastine treatment. In lymphocytes isolated from Sézary syndrome patients, the CD4-positive fraction underwent apoptosis after clemastine treatment, while CD4-negative lymphocytes were little affected. Because both c-Myc and STAT transcription factors are highly expressed in proliferating tumours, their inhibition by clemastine, desloratadine and other inhibitors could complement established chemotherapies not only for cutaneous T-cell lymphomas but perhaps also other cancers.

  11. Idiopathic pancreatitis in a patient with a STAT3 mutation

    PubMed Central

    Peppers, Brian; Frith, John; Tcheurekdjian, Haig; Hostoffer, Robert

    2016-01-01

    Background: Hyperimmunoglobulin E syndrome (HIES) is a rare primary immunodeficiency characterized by recurrent skin infections with abscesses, recurrent pneumonias with pneumatoceles, and immunoglobulin E levels of >10 times the upper limit of normal. Case: The patient described herein had a classic case of signal transducer and activator of transcription 3 (STAT3) deficiency associated with HIES diagnosed several years before this particular presentation. He demonstrated extraimmune manifestations of the disease as well, including characteristic facies and a history of skeletal fractures. In addition, the patient had several distinct episodes of idiopathic pancreatitis for which a full gastrointestinal workup had been performed. STAT3 mutation was confirmed by genotyping at the time of diagnosis of HIES. Conclusions: STAT3, a mammalian protein that regulates cell growth, survival, and differentiation, has been linked to human pancreatic carcinogenesis as well as the above-mentioned immune deficiency. Mouse studies demonstrated that genetic ablation of STAT3 exacerbates the course of acute pancreatitis, whereas normal pancreatic STAT3 seems to have a protective effect against necrotizing pancreatitis. An association between STAT3 mutations and pancreatitis has not yet been revealed in humans. Here we describe a case of acute pancreatitis that presented in a patient with STAT3 mutation. PMID:27103560

  12. Hepatocyte-specific Smad7 deletion accelerates DEN-induced HCC via activation of STAT3 signaling in mice

    PubMed Central

    Feng, T; Dzieran, J; Yuan, X; Dropmann, A; Maass, T; Teufel, A; Marhenke, S; Gaiser, T; Rückert, F; Kleiter, I; Kanzler, S; Ebert, M P; Vogel, A; ten Dijke, P; Dooley, S; Meindl-Beinker, N M

    2017-01-01

    TGF-β signaling in liver cells has variant roles in the dynamics of liver diseases, including hepatocellular carcinoma (HCC). We previously found a correlation of high levels of the important endogenous negative TGF-β signaling regulator SMAD7 with better clinical outcome in HCC patients. However, the underlying tumor-suppressive molecular mechanisms are still unclear. Here, we show that conditional (TTR-Cre) hepatocyte-specific SMAD7 knockout (KO) mice develop more tumors than wild-type and corresponding SMAD7 transgenic mice 9 months after diethylnitrosamine (DEN) challenge, verifying SMAD7 as a tumor suppressor in HCC. In line with our findings in patients, Smad7 levels in both tumor tissue as well as surrounding tissue show a significant inverse correlation with tumor numbers. SMAD7 KO mice presented with increased pSMAD2/3 levels and decreased apoptosis in the tumor tissue. Higher tumor incidence was accompanied by reduced P21 and upregulated c-MYC expression in the tumors. Activation of signal transducer and activator of transcription factor 3 signaling was found in Smad7-deficient mouse tumors and in patients with low tumoral SMAD7 expression as compared with surrounding tissue. Together, our results provide new mechanistic insights into the tumor-suppressive functions of SMAD7 in hepatocarcinogenesis. PMID:28134936

  13. Modulation of Stat3 Alternative Splicing in Breast Cancer

    DTIC Science & Technology

    2010-09-01

    The views, opinions and/or findings contained in this report are those of the author(s) and should not be construed as an...Stat3 Alternative Splicing in Breast Cancer Dr. Luca Cartegni Sloan-Kettering Institute New York, NY 10021 Stat3 is a transcription factor...constitutively active in a large number of breast cancers and other tumors, where it works as a central player in the activation of multiple oncogenic pathways

  14. IL-22(+)CD4(+) T cells promote colorectal cancer stemness via STAT3 transcription factor activation and induction of the methyltransferase DOT1L.

    PubMed

    Kryczek, Ilona; Lin, Yanwei; Nagarsheth, Nisha; 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

    2014-05-15

    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 that negatively affects patient outcome. Efforts to target this network might be a strategy in treating colorectal cancer patients.

  15. Induction of caspase-dependent extrinsic apoptosis by apigenin through inhibition of signal transducer and activator of transcription 3 (STAT3) signalling in HER2-overexpressing BT-474 breast cancer cells.

    PubMed

    Seo, Hye-Sook; Jo, Jae Kyung; Ku, Jin Mo; Choi, Han-Seok; Choi, Youn Kyung; Woo, Jong-Kyu; Kim, Hyo In; Kang, Soo-Yeon; Lee, Kang Min; Nam, Koong Won; Park, Namkyu; Jang, Bo-Hyoung; Shin, Yong Cheol; Ko, Seong-Gyu

    2015-10-23

    Phytoestrogen intake is known to be beneficial to decrease breast cancer incidence and progression. But its molecular mechanisms of action are still unknown. The present study aimed to examine the effect of apigenin on proliferation and apoptosis in HER2-expressing breast cancer cells. In our experiments, apigenin inhibited the proliferation of BT-474 cells in a dose- and time-dependent manner. Apigenin also inhibited clonogenic survival (anchorage-dependent and -independent) of BT-474 cells in a dose-dependent manner. These growth inhibitions were accompanied with an increase in sub-G0/G1 apoptotic populations. Apigenin-induced extrinsic a caspase-dependent apoptosis up-regulating the levels of cleaved caspase-8 and cleaved caspase-3, and inducing the cleavage of poly (ADP-ribose) polymerase (PARP). Whereas, apigenin did not induce apoptosis via intrinsic mitochondrial apoptosis pathway since this compound did not decrease mitochondrial membrane potential without affecting the levels of B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (BAX). Apigenin reduced the expression of phospho-JAK1, phospho-JAK2 and phospho-STAT3 and decreased signal transducer and activator of transcription 3 (STAT3) dependent luciferase reporter gene activity in BT-474 cells. Apigenin inhibited CoCl2-induced VEGF secretion and decreased the nuclear translocation of STAT3. Our study indicates that apigenin induces apoptosis through inhibition of STAT3 signalling and could serve as a useful compound to prevent or treat HER2-overexpressing breast cancer.

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

    SciTech Connect

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

    2015-06-05

    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. - Highlights: • HBV endows HCC cells with resistance to STAT3 inactivation on proliferation. • Abnormal ERK activation after STAT3 inhibition in HBV-related HCC cells. • Combined ERK and STAT3 inhibition eliminates the discrepancy. • STAT3 inhibition moderately reduces HBV expression.

  17. STAT3 phosphorylation in injured axons before sensory and motor neuron nuclei: potential role for STAT3 as a retrograde signaling transcription factor.

    PubMed

    Lee, Nancy; Neitzel, Karen L; Devlin, Brenda K; MacLennan, A John

    2004-07-05

    STAT3 is a latent transcription factor that is activated by plasma membrane growth factor receptor complexes. Conditional gene disruption data indicate that it contributes to the survival of cranial motor neurons after peripheral nerve lesion. In agreement, levels of activated STAT3 (Tyr705-phosphorylated STAT3) have been shown to increase in the nuclei of adult cranial motor neurons during their regeneration after the same injury. The data presented here demonstrate that STAT3 is similarly but not identically affected in sciatic motor neurons after sciatic nerve injury. In addition, we find that sensory neuron nuclei also display an analogous increase in activated STAT3, thereby supporting a role for STAT3 in the survival and regeneration of these cells. Most interesting, the present data indicate that peripheral nerve lesion leads to a very rapid activation of STAT3 in axons at the lesion site. This response increases during the first 24 hours after injury and extends back to the motor and sensory neurons such that phospho-STAT3-immunoreactive axons are first detected in the dorsal root ganglia and ventral spinal cord at the same postlesion time intervals at which the activated STAT3 is first detected in the neuronal nuclei. Together these data raise the possibility that axonal STAT3, activated at the injury site, acts as a retrograde signaling transcription factor, which promotes the survival and regeneration of both sensory and motor neurons.

  18. Pancreatic STAT3 protects mice against caerulein-induced pancreatitis via PAP1 induction.

    PubMed

    Shigekawa, Minoru; Hikita, Hayato; Kodama, Takahiro; Shimizu, Satoshi; Li, Wei; Uemura, Akio; Miyagi, Takuya; Hosui, Atsushi; Kanto, Tatsuya; Hiramatsu, Naoki; Tatsumi, Tomohide; Takeda, Kiyoshi; Akira, Shizuo; Takehara, Tetsuo

    2012-12-01

    The signal transducer and activator of transcription 3 (STAT3) is a transcription factor that controls expressions of several genes involved in cell survival, proliferation and differentiation, and tissue inflammation. However, the significance of pancreatic STAT3 in acute pancreatitis remains unclear. We generated conditional STAT3 knockout (stat3(Δ/Δ)) mice by crossing stat3(flox/flox) mice with Pdx1-promoter Cre transgenic mice. Caerulein administration activated pancreatic STAT3 and induced acute pancreatitis as early as 3 hours in wild-type mice, and full recovery from the induced pancreatic injury was observed within 7 days. The levels of serum amylase and lipase and histologic scores of pancreatic necrosis and inflammatory cell infiltration were significantly higher at 3 hours in stat3(Δ/Δ) mice than in stat3(flox/flox) mice. Pancreatic recovery after pancreatitis was significantly delayed in stat3(Δ/Δ) mice compared with stat3(flox/flox) mice. Although stat3(flox/flox) mice had marked production in the pancreas of pancreatitis-associated protein 1 (PAP1), a serum acute phase protein, this induction was completely abrogated in stat3(Δ/Δ) mice. Enforced production of PAP1 by a hydrodynamic procedure in the liver significantly suppressed pancreatic necrosis and inflammation and also promoted pancreatic regeneration and recovery in stat3(Δ/Δ) mice to levels similar to those observed in stat3(flox/flox) mice. In conclusion, pancreatic STAT3 is indispensable for PAP1 production, and this STAT3/PAP1 pathway plays a protective role in caerulein-induced pancreatitis.

  19. ENMD-1198, a novel tubulin-binding agent reduces HIF-1alpha and STAT3 activity in human hepatocellular carcinoma(HCC) cells, and inhibits growth and vascularization in vivo

    PubMed Central

    Moser, Christian; Lang, Sven A; Mori, Akira; Hellerbrand, Claus; Schlitt, Hans J; Geissler, Edward K; Fogler, William E; Stoeltzing, Oliver

    2008-01-01

    Background Hepatocellular carcinoma (HCC) represents a highly vascularized tumor entity and the process of angiogenesis is essential for the growth of HCC. Importantly, the pro-angiogenic transcription factors HIF-1α and STAT3 have been implicated in HCC progression, thus representing interesting targets for molecular targeted therapy. We hypothesized that therapeutic inhibition of HIF-1α could be achieved by using a novel tubulin-binding agent (ENMD-1198). ENMD-1198 is an analog of 2-methoxyestradiol (2ME2) with antiproliferative and antiangiogenic activity. Methods The human HCC cell lines HUH-7 and HepG2 were used for experiments. Effects of ENMD-1198 on constitutive and inducible (hypoxia, growth factors) activation of signaling cascades, including HIF-1α and STAT3, were investigated by Western blotting. Changes in VEGF expression were determined by real-time PCR. Effects of ENMD-1198 on cancer cell migration and invasion were evaluated in in vitro-assays. The growth-inhibitory effects of ENMD-1198 (200 mg/kg/day) were determined in a subcutaneous tumor model (HUH-7). Results ENMD-1198 inhibited the phosphorylation of MAPK/Erk, PI-3K/Akt and FAK. Moreover, activation of HIF-1α and STAT3 was dramatically reduced by ENMD-1198, which resulted in lower VEGF mRNA expression (P < 0.05). In addition, tumor cell migratory and invasive properties were significantly inhibited (P < 0.05, for both). In vivo, treatment with ENMD-1198 led to a significant reduction in tumor growth, tumor vascularization, and numbers of proliferating tumor cells (P < 0.05 for all). Conclusion The novel microtubule destabilizing agent ENMD-1198 is suitable for inhibiting HIF-1α and STAT3 in human HCC cells and leads to reduced tumor growth and vascularization in vivo. Hence, inhibition of HIF-1α and STAT3 could prove valuable for therapy of hepatocellular carcinoma. PMID:18651980

  20. Activation of a pro-survival pathway IL-6/JAK2/STAT3 contributes to glial fibrillary acidic protein induction during the cholera toxin-induced differentiation of C6 malignant glioma cells.

    PubMed

    Shu, Minfeng; Zhou, Yuxi; Zhu, Wenbo; Wu, Sihan; Zheng, Xiaoke; Yan, Guangmei

    2011-06-01

    Differentiation-inducing therapy has been proposed to be a novel potential approach to treat malignant gliomas. Glial fibrillary acidic protein (GFAP) is a well-known specific astrocyte biomarker and acts as a tumor suppressor gene (TSG) in glioma pathogenesis. Previously we reported that a traditional biotoxin cholera toxin could induce malignant glioma cell differentiation characterized by morphologic changes and dramatic GFAP expression. However, the molecular mechanisms underlying GFAP induction are still largely unknown. Here we demonstrate that an oncogenic pathway interleukin-6/janus kinase-2/signal transducer and activator of transcription 3 (IL-6/JAK2/STAT3) cascade mediates the cholera toxin-induced GFAP expression. Cholera toxin dramatically stimulated GFAP expression at the transcriptional level in C6 glioma cells. Meanwhile, phosphorylation of STAT3 and JAK2 was highly induced in a time-dependent manner after cholera toxin incubation, whereas no changes of STAT3 and JAK2 were observed. Furthermore, the IL-6 gene was quickly induced by cholera toxin and subsequent IL-6 protein secretion was stimulated. Importantly, exogenous recombinant rat IL-6 can also induce phosphorylation of STAT3 concomitant with GFAP expression while JAK2 specific inhibitor AG490 could effectively block both cholera toxin- and IL-6-induced GFAP expression. Given that the methylation of the STAT3 binding element can suppress GFAP expression, we detected the methylation status of the critical recognition sequence of STAT3 in the promoter of GFAP gene (-1518 ∼ -1510) and found that it was unmethylated in C6 glioma cells. In addition, neither DNA methyltransferase1 (DNMT1) inhibitor 5-Aza-2'-deoxycytidine (5-AZa-CdR) nor silencing DNMT1 can stimulate GFAP expression, indicating that the loss of GFAP expression in C6 cells is not caused by its promoter hypermethylation. Taken together, our findings suggest that activation of a pro-survival IL-6/JAK2/STAT3 cascade contributes to

  1. STAT3 as a target for inducing apoptosis in solid and hematological tumors

    PubMed Central

    Siddiquee, Khandaker Al Zaid; Turkson, James

    2008-01-01

    Studies in the past few years have provided compelling evidence for the critical role of aberrant Signal Transducer and Activator of Transcription 3 (STAT3) in malignant transformation and tumorigenesis. Thus, it is now generally accepted that STAT3 is one of the critical players in human cancer formation and represents a valid target for novel anticancer drug design. This review focuses on aberrant STAT3 and its role in promoting tumor cell survival and supporting the malignant phenotype. A brief evaluation of the current strategies targeting STAT3 for the development of novel anticancer agents against human tumors harboring constitutively active STAT3 will also be presented. PMID:18227858

  2. High mobility group box 1 induces the activation of the Janus kinase 2 and signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway in pancreatic acinar cells in rats, while AG490 and rapamycin inhibit their activation

    PubMed Central

    Wang, Guoliang; Zhang, Jingchao; Dui, Danhua; Ren, Haoyuan; Liu, Jin

    2016-01-01

    The pathogenesis of severe acute pancreatitis (SAP) remains unclear. The Janus kinase and signal transducer and activator of transcription (JAK/STAT) pathway is important for various cytokines and growth factors. This study investigated the effect of the late inflammatory factor high mobility group box 1 (HMGB1) on the activation of JAK2/STAT3 in pancreatic acinar cells and the inhibitory effects of AG490 (a JAK2 inhibitor) and rapamycin (a STAT3 inhibitor) on this pathway. Rat pancreatic acinar cells were randomly divided into the control, HMGB1, AG490, and rapamycin groups. The mRNA levels of JAK2 and STAT3 at 10, 30, 60, and 120 minutes were detected using reverse transcription polymerase chain reaction (RT-PCR). The protein levels of JAK2 and STAT3 at 60 and 120 minutes were observed using Western blotting. Compared with the control group, the HMGB1 group exhibited significantly increased levels of JAK2 mRNA at each time point; STAT3 mRNA at 30, 60, and 120 minutes; and JAK2 and STAT3 proteins at 60 and 120 minutes (p < 0.01). Compared with the HMGB1 group, the AG490 and rapamycin groups both exhibited significantly decreased levels of JAK2 mRNA at each time point (p < 0.05); STAT3 mRNA at 30, 60, and 120 minutes (p < 0.01); and JAK2 and STAT3 proteins at 60 and 120 minutes (p < 0.01). HMGB1 induces the activation of the JAK2/STAT3 signaling pathway in rat pancreatic acinar cells, and this activation can be inhibited by AG490 and rapamycin. The results of this study may provide new insights for the treatment of SAP. PMID:27754827

  3. Le Carbone, a charcoal supplement, modulates DSS-induced acute colitis in mice through activation of AMPKα and downregulation of STAT3 and caspase 3 dependent apoptotic pathways.

    PubMed

    Afrin, Mst Rejina; Arumugam, Somasundaram; Rahman, Md Azizur; Karuppagounder, Vengadeshprabhu; Sreedhar, Remya; Harima, Meilei; Suzuki, Hiroshi; Nakamura, Takashi; Miyashita, Shizuka; Suzuki, Kenji; Ueno, Kazuyuki; Watanabe, Kenichi

    2017-02-01

    Le Carbone (LC) is a charcoal supplement, which contains a large amount of dietary fibers. Several studies suggested that charcoal supplement may be beneficial for stomach disorders, diarrhea, gas and indigestion. But no studies address whether LC intake would suppress inflammation, cell proliferation or disease progression in colitis. In the present study, the effect of LC on experimental colitis induced by dextran sulfate sodium (DSS) in mice and its possible mechanism of action were examined. A study was designed for 8days, using C57BL/6 female mice that were administered with 3% DSS in drinking water for 7days followed by another 1day consumption of normal water with or without treatment. LC suspension was administered daily for 7days via oral gavage using 5mg/mouse in treatment group and normal group was supplied with drinking water. LC suspension significantly attenuated the loss of body weight and shortening of colon length induced by DSS. The disease activity index, histopathologic changes were significantly reduced by LC treatment. The inflammatory mediators TNFα, IL-1β, p-STAT3 and p-NF-κB induced in the colon by DSS were markedly suppressed by LC. The increased activation of AMPKα in the colon was also detected in LC group. Furthermore, the apoptotic marker protein cleaved caspase 3 was down-regulated and anti-apoptotic proteins Bcl2 and Bcl-xL were significantly up-regulated by LC treatment. Taken together, our results demonstrate the ability of LC to inhibit inflammation, apoptosis and give some evidence for its potential use as adjuvant treatment of inflammatory bowel disease.

  4. Cross-talk between KLF4 and STAT3 regulates axon regeneration

    NASA Astrophysics Data System (ADS)

    Qin, Song; Zou, Yuhua; Zhang, Chun-Li

    2013-10-01

    Cytokine-induced activation of signal transducer and activator of transcription 3 (STAT3) promotes the regrowth of damaged axons in the adult central nervous system (CNS). Here we show that KLF4 physically interacts with STAT3 upon cytokine-induced phosphorylation of tyrosine 705 (Y705) on STAT3. This interaction suppresses STAT3-dependent gene expression by blocking its DNA-binding activity. The deletion of KLF4 in vivo induces axon regeneration of adult retinal ganglion cells (RGCs) via Janus kinase (JAK)-STAT3 signalling. This regeneration can be greatly enhanced by exogenous cytokine treatment, or removal of an endogenous JAK-STAT3 pathway inhibitor called suppressor of cytokine signalling 3 (SOCS3). These findings reveal an unexpected cross-talk between KLF4 and activated STAT3 in the regulation of axon regeneration that might have therapeutic implications in promoting repair of injured adult CNS.

  5. Suppression of autophagy augments the radiosensitizing effects of STAT3 inhibition on human glioma cells

    SciTech Connect

    Yuan, Xiaopeng; Du, Jie; Hua, Song; Zhang, Haowen; Gu, Cheng; Wang, Jie; Yang, Lei; Huang, Jianfeng; Yu, Jiahua Liu, Fenju

    2015-01-15

    Radiotherapy is an essential component of the standard therapy for newly diagnosed glioblastoma. To increase the radiosensitivity of glioma cells is a feasible solution to improve the therapeutic effects. It has been suggested that inhibition of signal transducer and activator of transcription 3 (STAT3) can radiosensitize glioma cells, probably via the activation of mitochondrial apoptotic pathway. In this study, human malignant glioma cells, U251 and A172, were treated with an STAT3 inhibitor, WP1066, or a short hairpin RNA plasmid targeting STAT3 to suppress the activation of STAT3 signaling. The radiosensitizing effects of STAT3 inhibition were confirmed in glioma cells. Intriguingly, combination of ionizing radiation exposure and STAT3 inhibition triggered a pronounced increase of autophagy flux. To explore the role of autophagy, glioma cells were treated with 3-methyladenine or siRNA for autophagy-related gene 5, and it was demonstrated that inhibition of autophagy further strengthened the radiosensitizing effects of STAT3 inhibition. Accordingly, more apoptotic cells were induced by the dual inhibition of autophagy and STAT3 signaling. In conclusion, our data revealed a protective role of autophagy in the radiosensitizing effects of STAT3 inhibition, and inhibition of both autophagy and STAT3 might be a potential therapeutic strategy to increase the radiosensitivity of glioma cells. - Highlights: • Inactivation of STAT3 signaling radiosensitizes malignant glioma cells. • STAT3 inhibition triggers a significant increase of autophagy flux induced by ionizing radiation in glioma cells. • Suppression of autophagy further strengthens the radiosensitizing effects of STAT3 inhibition in glioma cells. • Dual inhibition of autophagy and STAT3 induce massive apoptotic cells upon exposure to ionizing radiation.

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

    PubMed

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

    2015-04-30

    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.

  7. STAT3 activation of miR-21 and miR-181b-1 via PTEN and CYLD are part of the epigenetic switch linking inflammation to cancer.

    PubMed

    Iliopoulos, Dimitrios; Jaeger, Savina A; Hirsch, Heather A; Bulyk, Martha L; Struhl, Kevin

    2010-08-27

    A transient inflammatory signal can initiate an epigenetic switch from nontransformed to cancer cells via a positive feedback loop involving NF-kappaB, Lin28, let-7, and IL-6. We identify differentially regulated microRNAs important for this switch and putative transcription factor binding sites in their promoters. 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, respectively, inhibit PTEN and CYLD tumor suppressors, leading to increased NF-kappaB activity required to maintain the transformed state. These STAT3-mediated regulatory circuits are required for the transformed state in diverse cell lines and tumor growth in xenografts, and their transcriptional signatures are observed in colon adenocarcinomas. Thus, STAT3 is not only a downstream target of IL-6 but, with miR-21, miR-181b-1, PTEN, and CYLD, is part of the positive feedback loop that underlies the epigenetic switch that links inflammation to cancer.

  8. STAT3 links IL-22 signaling in intestinal epithelial cells to mucosal wound healing.

    PubMed

    Pickert, Geethanjali; Neufert, Clemens; Leppkes, Moritz; Zheng, Yan; Wittkopf, Nadine; Warntjen, Moritz; Lehr, Hans-Anton; Hirth, Sebastian; Weigmann, Benno; Wirtz, Stefan; Ouyang, Wenjun; Neurath, Markus F; Becker, Christoph

    2009-07-06

    Signal transducer and activator of transcription (STAT) 3 is a pleiotropic transcription factor with important functions in cytokine signaling in a variety of tissues. However, the role of STAT3 in the intestinal epithelium is not well understood. We demonstrate that development of colonic inflammation is associated with the induction of STAT3 activity in intestinal epithelial cells (IECs). Studies in genetically engineered mice showed that epithelial STAT3 activation in dextran sodium sulfate colitis is dependent on interleukin (IL)-22 rather than IL-6. IL-22 was secreted by colonic CD11c(+) cells in response to Toll-like receptor stimulation. Conditional knockout mice with an IEC-specific deletion of STAT3 activity were highly susceptible to experimental colitis, indicating that epithelial STAT3 regulates gut homeostasis. STAT3(IEC-KO) mice, upon induction of colitis, showed a striking defect of epithelial restitution. Gene chip analysis indicated that STAT3 regulates the cellular stress response, apoptosis, and pathways associated with wound healing in IECs. Consistently, both IL-22 and epithelial STAT3 were found to be important in wound-healing experiments in vivo. In summary, our data suggest that intestinal epithelial STAT3 activation regulates immune homeostasis in the gut by promoting IL-22-dependent mucosal wound healing.

  9. STAT3 links IL-22 signaling in intestinal epithelial cells to mucosal wound healing

    PubMed Central

    Pickert, Geethanjali; Neufert, Clemens; Leppkes, Moritz; Zheng, Yan; Wittkopf, Nadine; Warntjen, Moritz; Lehr, Hans-Anton; Hirth, Sebastian; Weigmann, Benno; Wirtz, Stefan; Ouyang, Wenjun; Neurath, Markus F.

    2009-01-01

    Signal transducer and activator of transcription (STAT) 3 is a pleiotropic transcription factor with important functions in cytokine signaling in a variety of tissues. However, the role of STAT3 in the intestinal epithelium is not well understood. We demonstrate that development of colonic inflammation is associated with the induction of STAT3 activity in intestinal epithelial cells (IECs). Studies in genetically engineered mice showed that epithelial STAT3 activation in dextran sodium sulfate colitis is dependent on interleukin (IL)-22 rather than IL-6. IL-22 was secreted by colonic CD11c+ cells in response to Toll-like receptor stimulation. Conditional knockout mice with an IEC-specific deletion of STAT3 activity were highly susceptible to experimental colitis, indicating that epithelial STAT3 regulates gut homeostasis. STAT3IEC-KO mice, upon induction of colitis, showed a striking defect of epithelial restitution. Gene chip analysis indicated that STAT3 regulates the cellular stress response, apoptosis, and pathways associated with wound healing in IECs. Consistently, both IL-22 and epithelial STAT3 were found to be important in wound-healing experiments in vivo. In summary, our data suggest that intestinal epithelial STAT3 activation regulates immune homeostasis in the gut by promoting IL-22–dependent mucosal wound healing. PMID:19564350

  10. STAT3-dependent effects of IL-22 in human keratinocytes are counterregulated by sirtuin 1 through a direct inhibition of STAT3 acetylation.

    PubMed

    Sestito, Rosanna; Madonna, Stefania; Scarponi, Claudia; Cianfarani, Francesca; Failla, Cristina M; Cavani, Andrea; Girolomoni, Giampiero; Albanesi, Cristina

    2011-03-01

    IL-22 has a pathogenetic role in psoriasis, where it is responsible for the altered proliferation and differentiation of keratinocytes and induces inflammatory molecules. The IL-22-induced effects are mediated by STAT3, whose activity is proportional to acetylation in lysine (Lys)685 and phosphorylation in tyrosine (Tyr)705. Lys 685 acetylation of STAT3 is inhibited by sirtuin (SIRT)1, a class III deacetylase promoting keratinocyte differentiation. Due to the opposite effects of IL-22 and SIRT1, we investigated whether IL-22-induced effects in keratinocytes could be regulated by SIRT1 through control of STAT3. We found that SIRT1 opposes the IL-22-induced STAT3 activity by deacetylating STAT3 and reducing STAT3 Tyr705 phosphorylation. By controlling STAT3, SIRT1 also influences the IL-22-induced expression of molecules involved in proliferation and inflammation as well as proliferation and migration processes in cultured keratinocytes. Although SIRT1 levels were similar in keratinocytes of healthy individuals and patients with psoriasis, they were reduced in psoriatic skin lesions, with the lymphokine IFN-γ inhibiting SIRT1 expression. Concomitantly, IFN-γ enhanced basal acetylation of STAT3 and its phosphorylation induced by IL-22. In conclusion, STAT3-dependent IL-22 signaling and effects in keratinocytes are negatively regulated by SIRT1. In skin affected by psoriasis, SIRT1 is down-regulated by IFN-γ, which thus renders psoriatic keratinocytes more prone to respond to IL-22.

  11. A novel platinum compound inhibits constitutive Stat3 signaling and induces cell cycle arrest and apoptosis of malignant cells.

    PubMed

    Turkson, James; Zhang, Shumin; Mora, Linda B; Burns, Audrey; Sebti, Said; Jove, Richard

    2005-09-23

    Previous studies have established constitutive activation of Stat3 protein as one of the molecular changes required for tumorigenesis. To develop novel therapeutics for tumors harboring constitutively active Stat3, compounds from the NCI 2000 diversity set were evaluated for inhibition of Stat3 DNA-binding activity in vitro. Of these, a novel platinum (IV) compound, IS3 295, interacted with Stat3 and inhibited its binding to specific DNA-response elements. Further analysis suggested noncompetitive-type kinetics for the inhibition of Stat3 binding to DNA. In human and mouse tumor cell lines with constitutively active Stat3, IS3 295 selectively attenuated Stat3 signaling, thereby inducing cell growth arrest at G0/G1 phase and apoptosis. Moreover, in transformed cells, IS3 295 repressed expression of cyclin D1 and bcl-xL, two of the known Stat3-regulated genes that are overexpressed in malignant cells, suggesting that IS3 295 mediates anti-tumor cell activity in part by blocking Stat3-mediated sub-version of cell growth and apoptotic signals. Together, our findings provide evidence for the inhibition of Stat3 activity and biological functions by IS3 295 through interaction with Stat3 protein. This study represents a significant advance in small molecule-based approaches to target Stat3 and suggests potential new applications for platinum (IV) complexes as modulators of the Stat3 pathway for cancer therapy.

  12. A signal transducer and activator of transcription 3·Nuclear Factor κB (Stat3·NFκB) complex is necessary for the expression of fascin in metastatic breast cancer cells in response to interleukin (IL)-6 and tumor necrosis factor (TNF)-α.

    PubMed

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

    2014-10-24

    IL-6 mediated activation of Stat3 is a major signaling pathway in the process of breast cancer metastasis. One important mechanism by which the IL-6/Stat3 pathway promotes metastasis is through transcriptional regulation of the actin-bundling protein fascin. In this study, we further analyzed the transcriptional regulation of the fascin gene promoter. We show that in addition to IL-6, TNF-α increases Stat3 and NFκB binding to the fascin promoter to induce its expression. We also show that NFκB is required for Stat3 recruitment to the fascin promoter in response to IL-6. Furthermore, Stat3 and NFκB form a protein complex in response to cytokine stimulation. Finally, we demonstrate that an overlapping STAT/NFκB site in a highly conserved 160-bp region of the fascin promoter is sufficient and necessary to induce transcription in response to IL-6 and TNF-α.

  13. Myeloid STAT3 promotes formation of colitis-associated colorectal cancer in mice

    PubMed Central

    Pathria, Paulina; Gotthardt, Dagmar; Prchal-Murphy, Michaela; Putz, Eva-Maria; Holcmann, Martin; Schlederer, Michaela; Grabner, Beatrice; Crncec, Ilija; Svinka, Jasmin; Musteanu, Monica; Hoffmann, Thomas; Filipits, Martin; Berger, Walter; Poli, Valeria; Kenner, Lukas; Bilban, Martin; Casanova, Emilio; Müller, Mathias; Strobl, Birgit; Bayer, Editha; Mohr, Thomas; Sexl, Veronika; Eferl, Robert

    2015-01-01

    Myeloid cells lacking STAT3 promote antitumor responses of NK and T cells but it is unknown if this crosstalk affects development of autochthonous tumors. We deleted STAT3 in murine myeloid cells (STAT3Δm) and examined the effect on the development of autochthonous colorectal cancers (CRCs). Formation of Azoxymethane/Dextransulfate (AOM/DSS)-induced CRCs was strongly suppressed in STAT3Δm mice. Gene expression profiling showed strong activation of T cells in the stroma of STAT3Δm CRCs. Moreover, STAT3Δm host mice were better able to control the growth of transplanted MC38 colorectal tumor cells which are known to be killed in a T cell-dependent manner. These data suggest that myeloid cells lacking STAT3 control formation of CRCs mainly via cross activation of T cells. Interestingly, the few CRCs that formed in STAT3Δm mice displayed enhanced stromalization but appeared normal in size indicating that they have acquired ways to escape enhanced tumor surveillance. We found that CRCs in STAT3Δm mice consistently activate STAT3 signaling which is implicated in immune evasion and might be a target to prevent tumor relapse. PMID:26137415

  14. Small-molecule inhibition of STAT3 in radioresistant head and neck squamous cell carcinoma

    PubMed Central

    Bharadwaj, Uddalak; Eckols, T. Kris; Xu, Xuejun; Kasembeli, Moses M.; Chen, Yunyun; Adachi, Makoto; Song, Yongcheng; Mo, Qianxing; Lai, Stephen Y.; Tweardy, David J.

    2016-01-01

    While STAT3 has been validated as a target for treatment of many cancers, including head and neck squamous cell carcinoma (HNSCC), a STAT3 inhibitor is yet to enter the clinic. We used the scaffold of C188, a small-molecule STAT3 inhibitor previously identified by us, in a hit-to-lead program to identify C188-9. C188-9 binds to STAT3 with high affinity and represents a substantial improvement over C188 in its ability to inhibit STAT3 binding to its pY-peptide ligand, to inhibit cytokine-stimulated pSTAT3, to reduce constitutive pSTAT3 activity in multiple HNSCC cell lines, and to inhibit anchorage dependent and independent growth of these cells. In addition, treatment of nude mice bearing xenografts of UM-SCC-17B, a radioresistant HNSCC line, with C188-9, but not C188, prevented tumor xenograft growth. C188-9 treatment modulated many STAT3-regulated genes involved in oncogenesis and radioresistance, as well as radioresistance genes regulated by STAT1, due to its potent activity against STAT1, in addition to STAT3. C188-9 was well tolerated in mice, showed good oral bioavailability, and was concentrated in tumors. Thus, C188-9, either alone or in combination with radiotherapy, has potential for use in treating HNSCC tumors that demonstrate increased STAT3 and/or STAT1 activation. PMID:27027445

  15. SIRT1 activation enhances HDAC inhibition-mediated upregulation of GADD45G by repressing the binding of NF-κB/STAT3 complex to its promoter in malignant lymphoid cells

    PubMed Central

    Scuto, A; Kirschbaum, M; Buettner, R; Kujawski, M; Cermak, J M; Atadja, P; Jove, R

    2013-01-01

    We explored the activity of SIRT1 activators (SRT501 and SRT2183) alone and in combination with panobinostat in a panel of malignant lymphoid cell lines in terms of biological and gene expression responses. SRT501 and SRT2183 induced growth arrest and apoptosis, concomitant with deacetylation of STAT3 and NF-κB, and reduction of c-Myc protein levels. PCR arrays revealed that SRT2183 leads to increased mRNA levels of pro-apoptosis and DNA-damage-response genes, accompanied by accumulation of phospho-H2A.X levels. Next, ChIP assays revealed that SRT2183 reduces the DNA-binding activity of both NF-κB and STAT3 to the promoter of GADD45G, which is one of the most upregulated genes following SRT2183 treatment. Combination of SRT2183 with panobinostat enhanced the anti-growth and anti-survival effects mediated by either compound alone. Quantitative-PCR confirmed that the panobinostat in combination with SRT2183, SRT501 or resveratrol leads to greater upregulation of GADD45G than any of the single agents. Panobinostat plus SRT2183 in combination showed greater inhibition of c-Myc protein levels and phosphorylation of H2A.X, and increased acetylation of p53. Furthermore, EMSA revealed that NF-κB binds directly to the GADD45G promoter, while STAT3 binds indirectly in complexes with NF-κB. In addition, the binding of NF-κB/STAT3 complexes to the GADD45G promoter is inhibited following panobinostat, SRT501 or resveratrol treatment. Moreover, the combination of panobinostat with SRT2183, SRT501 or resveratrol induces a greater binding repression than either agent alone. These data suggest that STAT3 is a corepressor with NF-κB of the GADD45G gene and provides in vitro proof-of-concept for the combination of HDACi with SIRT1 activators as a potential new therapeutic strategy in lymphoid malignancies. PMID:23681230

  16. STAT3 Inhibition by Microtubule-Targeted Drugs: Dual Molecular Effects of Chemotherapeutic Agents

    PubMed Central

    Walker, Sarah R.; Chaudhury, Mousumi; Frank, David A.

    2011-01-01

    To improve the effectiveness of anti-cancer therapies, it is necessary to identify molecular targets that are essential to a tumor cell but dispensable in a normal cell. Increasing evidence indicates that the transcription factor STAT3, which regulates the expression of genes controlling proliferation, survival, and self-renewal, constitutes such a target. Recently it has been found that STAT3 can associate with the cytoskeleton. Since many of the tumors in which STAT3 is activated, such as breast cancer and ovarian cancer, are responsive to drugs that target microtubules, we examined the effect of these compounds on STAT3. We found that microtubule stabilizers, such as paclitaxel, or microtubule inhibitors, such as vinorelbine, decrease the activating tyrosine phosphorylation of STAT3 in tumor cells and inhibit the expression of STAT3 target genes. Paclitaxel decreases the association between STAT3 and microtubules, and appears to decrease STAT3 phosphorylation through induction of a negative feedback regulator. The cytotoxic activity of paclitaxel in breast cancer cell lines correlates with its ability to decrease STAT3 phosphorylation. However, consistent with the necessity for expression of a negative regulator, treatment of resistant MDA-MB-231 cells with the DNA demethylating agent 5-azacytidine restores the ability of paclitaxel to block STAT3-dependent gene expression. Finally, the combination of paclitaxel and agents that directly target STAT3 has beneficial effects in killing STAT3-dependent cell lines. Thus, microtubule-targeted agents may exert some of their effects by inhibiting STAT3, and understanding this interaction may be important for optimizing rational targeted cancer therapies. PMID:21949561

  17. Nifuroxazide inhibits survival of multiple myeloma cells by directly inhibiting STAT3.

    PubMed

    Nelson, Erik A; Walker, Sarah R; Kepich, Alicia; Gashin, Laurie B; Hideshima, Teru; Ikeda, Hiroshi; Chauhan, Dharminder; Anderson, Kenneth C; Frank, David A

    2008-12-15

    Constitutive activation of the transcription factor STAT3 contributes to the pathogenesis of many cancers, including multiple myeloma (MM). Since STAT3 is dispensable in most normal tissue, targeted inhibition of STAT3 is an attractive therapy for patients with these cancers. To identify STAT3 inhibitors, we developed a transcriptionally based assay and screened a library of compounds known to be safe in humans. We found the drug nifuroxazide to be an effective inhibitor of STAT3 function. Nifuroxazide inhibits the constitutive phosphorylation of STAT3 in MM cells by reducing Jak kinase autophosphorylation, and leads to down-regulation of the STAT3 target gene Mcl-1. Nifuroxazide causes a decrease in viability of primary myeloma cells and myeloma cell lines containing STAT3 activation, but not normal peripheral blood mononuclear cells. Although bone marrow stromal cells provide survival signals to myeloma cells, nifuroxazide can overcome this survival advantage. Reflecting the interaction of STAT3 with other cellular pathways, nifuroxazide shows enhanced cytotoxicity when combined with either the histone deacetylase inhibitor depsipeptide or the MEK inhibitor UO126. Therefore, using a mechanistic-based screen, we identified the clinically relevant drug nifuroxazide as a potent inhibitor of STAT signaling that shows cytotoxicity against myeloma cells that depend on STAT3 for survival.

  18. Δ9-Tetrahydrocannabinol-mediated epigenetic modifications elicit myeloid-derived suppressor cell activation via STAT3/S100A8

    PubMed Central

    Sido, Jessica Margaret; Yang, Xiaoming; Nagarkatti, Prakash S.; Nagarkatti, Mitzi

    2015-01-01

    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

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

    SciTech Connect

    Huang, Hanhui; Zhao, Wenrong; Yang, Dan

    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.

  20. Sodium orthovanadate suppresses palmitate-induced cardiomyocyte apoptosis by regulation of the JAK2/STAT3 signaling pathway.

    PubMed

    Liu, Jing; Fu, Hui; Chang, Fen; Wang, Jinlan; Zhang, Shangli; Caudle, Yi; Zhao, Jing; Yin, Deling

    2016-05-01

    Elevated circulatory free fatty acids (FFAs) especially saturated FFAs, such as palmitate (PA), are detrimental to the heart. However, mechanisms responsible for this phenomenon remain unknown. Here, the role of JAK2/STAT3 in PA-induced cytotoxicity was investigated in cardiomyocytes. We demonstrate that PA suppressed the JAK2/STAT3 pathway by dephosphorylation of JAK2 (Y1007/1008) and STAT3 (Y705), and thus blocked the translocation of STAT3 into the nucleus. Conversely, phosphorylation of S727, another phosphorylated site of STAT3, was increased in response to PA treatment. Pretreatment of JNK inhibitor, but not p38 MAPK inhibitor, inhibited STAT3 (S727) activation induced by PA and rescued the phosphorylation of STAT3 (Y705). The data suggested that JNK may be another upstream factor regulating STAT3, and verified the important function of P-STAT3 (Y705) in PA-induced cardiomyocyte apoptosis. Sodium orthovanadate (SOV), a protein tyrosine phosphatase inhibitor, obviously inhibited PA-induced apoptosis by restoring JAK2/STAT3 pathways. This effect was diminished by STAT3 inhibitor Stattic. Collectively, our data suggested a novel mechanism that the inhibition of JAK2/STAT3 activation was responsible for palmitic lipotoxicity and SOV may act as a potential therapeutic agent by targeting JAK2/STAT3 in lipotoxic cardiomyopathy treatment.

  1. STAT3 as a potential therapeutic target in ALDH+ and CD44+/CD24+ stem cell-like pancreatic cancer cells

    PubMed Central

    Lin, Li; Jou, David; Wang, Yina; Ma, Haiyan; Liu, Tianshu; Fuchs, James; Li, Pui-Kai; Lü, Jiagao; Li, Chenglong; Lin, Jiayuh

    2016-01-01

    Persistent activation of signal transducers and activators of transcription 3 (STAT3) is commonly detected in many types of cancer including pancreatic cancer. Whether STAT3 is activated in stem cell-like pancreatic cancer cells and the effect of STAT3 inhibition, is still unknown. Flow cytometry was used to isolate pancreatic cancer stem-like cells which are identified by both aldehyde dehydrogenase (ALDH)-positive (ALDH+) as well as cluster of differentiation (CD) 44-positive/CD24-positive subpopulations (CD44+/CD24+). STAT3 activation and the effects of STAT3 inhibition by STAT3 inhibitors, LLL12, FLLL32, and Stattic in ALDH+ and CD44+/CD24+ cells were examined. Our results showed that ALDH+ and CD44+/CD24+ pancreatic cancer stem-like cells expressed higher levels of phosphorylated STAT3, an active form of STAT3, compared to ALDH-negative (ALDH−) and CD44-negative/CD24-negative (CD44−/CD24−) pancreatic cancer cells, suggesting that STAT3 is activated in pancreatic cancer stem-like cells. Small molecular STAT3 inhibitors inhibited STAT3 phosphorylation, STAT3 downstream target gene expression, cell viability, and tumorsphere formation in ALDH+ and CD44+/CD24+ cells. Our results indicate that STAT3 is a novel therapeutic target in pancreatic cancer stem-like cells and inhibition of activated STAT3 in these cells by STAT3 inhibitors may offer an effective treatment for pancreatic cancer. PMID:27748818

  2. Involvement of Stat3 in mouse brain development and sexual dimorphism: a proteomics approach.

    PubMed

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

    2010-11-29

    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 in the brain and the hypothesis of a gender-linked modulation of STAT3, we analyzed a neuron-specific STAT3 knockout mouse model investigating the influence of STAT3 activity in brain protein expression pattern in both males and females in the absence of neurological insult. We performed a proteomic study aimed to reveal the molecular pathways directly or indirectly controlled by STAT3 underscoring its role in brain development and maintenance. We identified several proteins, belonging to different neuronal pathways such as energy metabolism or synaptic transmission, controlled by STAT3 that confirm its crucial role in brain development and maintenance. Moreover, we investigated the different processes that could contribute to the sexual dimorphic behavior observed in the incidence of neurological and mental disease. Interestingly both STAT3 KO and gender factors influence the expression of several mitochondrial proteins conferring to mitochondrial activity high importance in the regulation of brain physiology and conceivable relevance as therapeutic target.

  3. Significance of Stat3 Signaling in Epithelial Cell Differentiation of Fetal Mouse Lungs

    PubMed Central

    Kameyama, Hiroki; Kudoh, Shinji; Hatakeyama, Jun; Matuo, Akira; Ito, Takaaki

    2017-01-01

    To study the significance of signal transducer and activator of transcription (Stat) 3 in lung epithelial development of fetal mice, we examined fetal mouse lungs, focusing on the expression of Clara cell secretory protein (CCSP), Forkhead box protein J1 (Foxj1), calcitonin gene-related peptide (CGRP), phosphorylated Stat3 (Tyr705), and hairy/enhancer of split (Hes) 1, and observed cultured fetal lungs upon treatment with IL-6, a Stat3 activator, or cucurbitacin I, a Stat3 inhibitor. Moreover, the interaction of Stat3 signaling and Hes1 was studied using Hes1 gene-deficient mice. Phosphorylated Stat3 was detected in fetal lungs and, immunohistochemically, phosphorylated Stat3 was found to be co-localized in developing Clara cells, but not in ciliated cells. In the organ culture studies, upon treatment with IL-6, quantitative RT-PCR revealed that CCSP mRNA increased with increasing Stat3 phosphorylation, while cucurbitacin I decreased Hes1, CCSP, Foxj1 and CGRP mRNAs with decreasing Stat3 phosphorylation. In the lungs of Hes1 gene-deficient mice, Stat3 phosphorylation was not markedly different from wild-type mice, the expression of CCSP and CGRP was enhanced, and the treatment of IL-6 or cucurbitacin I induced similar effects on mouse lung epithelial differentiation regardless of Hes1 expression status. Stat3 signaling acts in fetal mouse lung development, and seems to regulate Clara cell differentiation positively. Hes1 could regulate Clara cell differentiation in a manner independent from Stat3 signaling. PMID:28386145

  4. STAT3 Expression, Molecular Features, Inflammation Patterns and Prognosis in a Database of 724 Colorectal Cancers

    PubMed Central

    Morikawa, Teppei; Baba, Yoshifumi; Yamauchi, Mai; Kuchiba, Aya; Nosho, Katsuhiko; Shima, Kaori; Tanaka, Noriko; Huttenhower, Curtis; Frank, David A.; Fuchs, Charles S.; Ogino, Shuji

    2010-01-01

    Purpose STAT3 (signal transducer and activator of transcription 3) is a transcription factor that is constitutively activated in some cancers. STAT3 appears to play crucial roles in cell proliferation and survival, angiogenesis, tumor-promoting inflammation and suppression of anti-tumor host immune response in the tumor microenvironment. Although the STAT3 signaling pathway is a potential drug target, clinical, pathologic, molecular or prognostic features of STAT3-activated colorectal cancer remain uncertain. Experimental Design Utilizing a database of 724 colon and rectal cancer cases, we evaluated phosphorylated STAT3 (p-STAT3) expression by immunohistochemistry. Cox proportional hazards model was used to compute mortality hazard ratio (HR), adjusting for clinical, pathologic and molecular features, including microsatellite instability (MSI), the CpG island methylator phenotype (CIMP), LINE-1 methylation, 18q loss of heterozygosity, TP53 (p53), CTNNB1 (β-catenin), JC virus T-antigen, and KRAS, BRAF, and PIK3CA mutations. Results Among the 724 tumors, 131 (18%) showed high-level p-STAT3 expression (p-STAT3-high), 244 (34%) showed low-level expression (p-STAT3-low), and the remaining 349 (48%) were negative for p-STAT3. p-STAT3 overexpression was associated with significantly higher colorectal cancer-specific mortality [log-rank p=0.0020; univariate HR (p-STAT3-high vs. p-STAT3-negative) 1.85, 95% confidence interval (CI) 1.30–2.63, Ptrend =0.0005; multivariate HR, 1.61, 95% CI 1.11–2.34, Ptrend =0.015). p-STAT3 expression was positively associated with peritumoral lymphocytic reaction (multivariate odds ratio 3.23; 95% CI, 1.89–5.53; p<0.0001). p-STAT3 expression was not associated with MSI, CIMP, or LINE-1 hypomethylation. Conclusions STAT3 activation in colorectal cancer is associated with adverse clinical outcome, supporting its potential roles as a prognostic biomarker and a chemoprevention and/or therapeutic target. PMID:21310826

  5. 2-Guanidinoquinazolines as new inhibitors of the STAT3 pathway

    PubMed Central

    LaPorte, Matthew G.; da Paz Lima, Dimas José; Zhang, Feng; Sen, Malabika; Grandis, Jennifer R.; Camarco, Daniel; Hua, Yun; Johnston, Paul A.; Lazo, John S.; Resnick, Lynn O.; Wipf, Peter; Huryn, Donna M.

    2014-01-01

    Synthesis and SAR investigation of 2-guanidinoquinazolines, initially identified in a high content screen for selective STAT3 pathway inhibitors, led to a more potent analog (11c) that demonstrated improved anti-proliferative activity against a panel of HNSCC cell lines. PMID:25288188

  6. Paeoniflorin inhibits human glioma cells via STAT3 degradation by the ubiquitin–proteasome pathway

    PubMed Central

    Nie, Xiao-hu; Ou-yang, Jia; Xing, Ying; Li, Dan-yan; Dong, Xing-yu; Liu, Ru-en; Xu, Ru-xiang

    2015-01-01

    We investigated the underlying mechanism for the potent proapoptotic effect of paeoniflorin (PF) on human glioma cells in vitro, focusing on signal transducer and activator of transcription 3 (STAT3) signaling. Significant time- and dose-dependent apoptosis and inhibition of proliferation were observed in PF-treated U87 and U251 glioma cells. Expression of STAT3, its active form phosphorylated STAT3 (p-STAT3), and several downstream molecules, including HIAP, Bcl-2, cyclin D1, and Survivin, were significantly downregulated upon PF treatment. Overexpression of STAT3 induced resistance to PF, suggesting that STAT3 was a critical target of PF. Interestingly, rapid downregulation of STAT3 was consistent with its accelerated degradation, but not with its dephosphorylation or transcriptional modulation. Using specific inhibitors, we demonstrated that the prodegradation effect of PF on STAT3 was mainly through the ubiquitin–proteasome pathway rather than via lysosomal degradation. These findings indicated that PF-induced growth suppression and apoptosis in human glioma cells through the proteasome-dependent degradation of STAT3. PMID:26508835

  7. Down-regulation of microRNA-9 leads to activation of IL-6/Jak/STAT3 pathway through directly targeting IL-6 in HeLa cell.

    PubMed

    Zhang, Jiangbo; Jia, Junqiao; Zhao, Lijun; Li, Xiaojun; Xie, Qing; Chen, Xiangmei; Wang, Jianliu; Lu, Fengmin

    2016-05-01

    MicroRNA-9 (miR-9) presents to exert distinct and even opposite functions in different kinds of tumors through targeting different cellular genes. However, its role in cervical adenocarcinoma remains uncertain. Here, we report that miR-9 is down-regulated in cervical adenocarcinoma due to its frequent promoter-hypermethylation and exerts its tumor suppressor role through inhibiting several novel target genes, including interleukin-6 (IL-6). The promoters of miR-9 precursors (mir-9-1, -2, and -3) were hypermethylated in cervical adenocarcinoma tissues. Demethylation treatment of HeLa dramatically increased the expression of mature miR-9. Both in vitro and in vivo functional experiments confirmed that miR-9 can inhibit the proliferation, migration, and malignant transformation abilities of HeLa cells. Bioinformatics methods and array-based RNA expression profiles were used to screen the downstream target genes of miR-9. Dual-luciferase reporting assay, real-time qPCR, and ELISA or Western blot confirmed four genes (CKAP2, HSPC159, IL-6, and TC10) to be novel direct target genes of miR-9. Pathway annotation analysis of the differently expressed genes (DEGs) induced by ectopic miR-9 expression revealed the enrichment in Jak/STAT3 pathway, which is one of the downstream pathways of IL-6. Ectopic expression of miR-9 in HeLa inhibited Jak/STAT3 signaling activity. Moreover, such effect could be partially reversed by the addition of exogenous IL-6. In conclusion, our results here present a tumor suppressor potential of miR-9 in cervical adenocarcinoma for the first time and suggest that miR-9 could repress tumorigenesis through inhibiting the activity of IL-6/Jak/STAT3 pathway.

  8. Induction of gp130-related cytokines and activation of JAK2/STAT3 pathway in astrocytes precedes up-regulation of glial fibrillary acidic protein in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine model of neurodegeneration: key signaling pathway for astrogliosis in vivo?

    PubMed

    Sriram, Krishnan; Benkovic, Stanley A; Hebert, Meleik A; Miller, Diane B; O'Callaghan, James P

    2004-05-07

    Reactive gliosis is a hallmark of disease-, trauma-, and chemical-induced damage to the central nervous system. The signaling pathways associated with this response to neural injury remain to be elucidated, but recent evidence implicates the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway. Here, we used the known dopaminergic neurotoxicant, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), to selectively damage striatal dopaminergic nerve terminals and elicit a glial response. We then analyzed changes in gene expression and protein phosphorylation, in vivo, to identify ligands and mediators of the JAK-STAT pathway that accompany glial activation. Administration of MPTP caused rapid tyrosine (Tyr-705) phosphorylation and nuclear translocation of STAT3 in striatal astrocytes, prior to the induction of glial fibrillary acidic protein mRNA and protein. Pharmacological protection of dopaminergic nerve terminals with nomifensine abolished MPTP-mediated phosphorylation and translocation of STAT3 and prevented induction of astrogliosis. Among the Janus kinase family of tyrosine kinases, only JAK2 was associated with the phosphorylation of STAT3 after MPTP and, inhibition of JAK2 by AG490, in vivo, attenuated both the phosphorylation of STAT3 and induction of GFAP. The p44/42 mitogen-activated protein kinase (MAPK; ERK1/2) also was activated by MPTP, but was not associated with activation of STAT3, because serine (Ser-727) was not phosphorylated. The mRNA for ligands of the gp130-JAK/STAT3 signaling pathway, interleukin-6, leukemia inhibitory factor, and oncostatin M were elevated prior to activation of STAT3 and induction of astrogliosis; neuroprotection with nomifensine blocked these effects of MPTP. Taken together, our results suggest that the gp130-mediated activation of JAK2/STAT3 signaling pathway may play a key role in the induction of astrogliosis.

  9. Association of STAT3 with Cx26 and Cx43 in human uterine endometrioid adenocarcinoma

    PubMed Central

    SULKOWSKA, URSZULA; FEBP, ANDRZEJ WINCEWICZ; SULKOWSKI, STANISLAW

    2016-01-01

    Signal transducer and activator of transcription-3 (STAT3) drives endometrial carcinogenesis, while signaling via gap junctions gets weakened during cancer progression. Connexin 26 (Cx26), Cx43 and STAT3 were immunohistochemically evaluated in 78 endometrioid adenocarcinomas: Nuclear expression of STAT3 positively correlated with cytoplasmic immunoreactivity to Cx43 (P=0.004, r=0.318) and Cx26 (P=0.006, r=0.309). STAT3 correlated with Cx43 (P=0.022, r=0.411) and Cx26 (P=0.008 r=0.466) in G1 tumors. A statistically significant linkage remained in G2 cancers between STAT3 and Cx43 (P=0.061, r=0.262) and Cx26 (P=0.016, r=0.331); however, no correlations were observed in G3 tumors. STAT3 was significantly associated with Cx 43 (p=0.003, r=0.684) and Cx26 (p=0.049, r=0.500) in estrogen receptor (ER) negative adenocarcinomas. STAT3 did not correlate with Cx43 in ER positive adenocarcinomas; however, STAT3 expression remained correlated with Cx26 expression (P=0.035, r=0.268). In progesterone receptor negative tumors STAT3 was significantly associated with Cx43 (P=0.035, r=0.451) and Cx26 (P<0.0001, r=0.707). However, in PgR positive adenocarcinomas STAT3 correlated with Cx43 (P=0.03, r=0.290) but not with Cx26. Thus, it appears that hormone dependent acceleration of cancer growth breaks the association between STAT3 and Cx expression. These associations become weaker as the tumors dedifferentiate from G1 to G3 endometrioid adenocarcinomas. The present study provides evidence that the loss of correlation between STAT3 and selected Cx proteins occurs in tumors with more aggressive behavior. PMID:27313754

  10. Γ-Ionizing radiation-induced activation of the EGFR-p38/ERK-STAT3/CREB-1-EMT pathway promotes the migration/invasion of non-small cell lung cancer cells and is inhibited by podophyllotoxin acetate.

    PubMed

    Cho, Jeong Hyun; Hong, Wan Gi; Jung, Yu-Jin; Lee, Jaeseok; Lee, Eunah; Hwang, Sang-Gu; Um, Hong-Duck; Park, Jong Kuk

    2016-06-01

    Here, we report a new intracellular signaling pathway involved in γ-ionizing radiation (IR)-induced migration/invasion and show that podophyllotoxin acetate (PA) inhibits the IR-induced invasion and migration of A549 cells (a non-small cell lung cancer (NSCLC) cell line). Our results revealed that IR increased the invasion/migration of A549 cells, and this effect was decreased by 10 nM PA treatment. PA also inhibited the expressions/activities of matrix metalloprotase (MMP) -2, MMP-9, and vimentin, suggesting that PA could block the IR-induced epithelial-mesenchymal transition (EMT). The IR-induced increases in invasion/migration were associated with the activation of EGFR-AKT, and PA inhibited this effect. P38 and p44/42 ERK were also involved in IR-induced invasion/migration, and combined treatments with PA plus inhibitors of each MAPK synergistically blocked this invasion/migration. In terms of transcription factors (TFs), IR-induced increases in cyclic AMP response element-binding protein-1 (CREB-1) and signal transducer and activator of transcription 3 (STAT3) increased invasion/migration and EMT. PA also inhibited these transcription factors and then blocked IR-induced invasion/migration. Collectively, these results indicate that IR induces cancer cell invasion/migration by activating the EGFR-p38/ERK-CREB-1/STAT3-EMT pathway and that PA blocks this pathway to inhibit IR-induced invasion/migration.

  11. STAT3 overexpression promotes metastasis in intrahepatic cholangiocarcinoma and correlates negatively with surgical outcome.

    PubMed

    Yang, Xin-Wei; Li, Liang; Hou, Guo-Jun; Yan, Xin-Zhou; Xu, Qin-Guo; Chen, Lei; Zhang, Bao-Hua; Shen, Feng

    2017-01-31

    Signal transducer and activator of transcription 3 (STAT3) promotes tumor progression in many types of cancer. In this study, we analyzed the prognostic value of this marker in human intrahepatic cholangiocarcinoma (ICC). Using real-time PCR, western blot and immunohistochemistry assays, we found that STAT3 is overexpressed in ICC patients. STAT3 expression correlated with several clinicopathological features, including tumor size, pathological satellite, vascular invasion, undifferentiated-type histology, lymph node metastasis and TNM stage in two independent cohorts of ICC patients. Patients with high STAT3 levels had a poor prognosis in terms of overall survival (OS) and disease-free survival (DFS). Multivariate survival analysis indicated that STAT3 is an independent prognostic factor for OS and DFS. Furthermore, we observed that STAT3 overexpression promotes the invasion, metastasis and proliferation of ICC cells in vitro and in vivo, and also promotes STAT3 phosphorylation. These findings suggest that STAT3 expression correlated negatively with surgical outcome and inhibition of STAT3 expression may constitute a novel target for the treatment of ICC patients.

  12. Necdin, a negative growth regulator, is a novel STAT3 target gene down-regulated in human cancer.

    PubMed

    Haviland, Rachel; Eschrich, Steven; Bloom, Gregory; Ma, Yihong; Minton, Susan; Jove, Richard; Cress, W Douglas

    2011-01-01

    Cytokine and growth factor signaling pathways involving STAT3 are frequently constitutively activated in many human primary tumors, and are known for the transcriptional role they play in controlling cell growth and cell cycle progression. However, the extent of STAT3's reach on transcriptional control of the genome as a whole remains an important question. We predicted that this persistent STAT3 signaling affects a wide variety of cellular functions, many of which still remain to be characterized. We took a broad approach to identify novel STAT3 regulated genes by examining changes in the genome-wide gene expression profile by microarray, using cells expressing constitutively-activated STAT3. Using computational analysis, we were able to define the gene expression profiles of cells containing activated STAT3 and identify candidate target genes with a wide range of biological functions. Among these genes we identified Necdin, a negative growth regulator, as a novel STAT3 target gene, whose expression is down-regulated at the mRNA and protein levels when STAT3 is constitutively active. This repression is STAT3 dependent, since inhibition of STAT3 using siRNA restores Necdin expression. A STAT3 DNA-binding site was identified in the Necdin promoter and both EMSA and chromatin immunoprecipitation confirm binding of STAT3 to this region. Necdin expression has previously been shown to be down-regulated in a melanoma and a drug-resistant ovarian cancer cell line. Further analysis of Necdin expression demonstrated repression in a STAT3-dependent manner in human melanoma, prostate and breast cancer cell lines. These results suggest that STAT3 coordinates expression of genes involved in multiple metabolic and biosynthetic pathways, integrating signals that lead to global transcriptional changes and oncogenesis. STAT3 may exert its oncogenic effect by up-regulating transcription of genes involved in promoting growth and proliferation, but also by down-regulating expression

  13. JAK/STAT3 pathway inhibition blocks skeletal muscle wasting downstream of IL-6 and in experimental cancer cachexia.

    PubMed

    Bonetto, Andrea; Aydogdu, Tufan; Jin, Xiaoling; Zhang, Zongxiu; Zhan, Rui; Puzis, Leopold; Koniaris, Leonidas G; Zimmers, Teresa A

    2012-08-01

    Cachexia, the metabolic dysregulation leading to sustained loss of muscle and adipose tissue, is a devastating complication of cancer and other chronic diseases. Interleukin-6 and related cytokines are associated with muscle wasting in clinical and experimental cachexia, although the mechanisms by which they might induce muscle wasting are unknown. One pathway activated strongly by IL-6 family ligands is the JAK/STAT3 pathway, the function of which has not been evaluated in regulation of skeletal muscle mass. Recently, we showed that skeletal muscle STAT3 phosphorylation, nuclear localization, and target gene expression are activated in C26 cancer cachexia, a model with high IL-6 family ligands. Here, we report that STAT3 activation is a common feature of muscle wasting, activated in muscle by IL-6 in vivo and in vitro and by different types of cancer and sterile sepsis. Moreover, STAT3 activation proved both necessary and sufficient for muscle wasting. In C(2)C(12) myotubes and in mouse muscle, mutant constitutively activated STAT3-induced muscle fiber atrophy and exacerbated wasting in cachexia. Conversely, inhibiting STAT3 pharmacologically with JAK or STAT3 inhibitors or genetically with dominant negative STAT3 and short hairpin STAT3 reduced muscle atrophy downstream of IL-6 or cancer. These results indicate that STAT3 is a primary mediator of muscle wasting in cancer cachexia and other conditions of high IL-6 family signaling. Thus STAT3 could represent a novel therapeutic target for the preservation of skeletal muscle in cachexia.

  14. Increased STAT3 phosphorylation on CD27(+) B-cells from common variable immunodeficiency disease patients.

    PubMed

    Clemente, Antonio; Pons, Jaume; Lanio, Nallibe; Cunill, Vanesa; Frontera, Guillem; Crespí, Catalina; Matamoros, Núria; Ferrer, Joana M

    2015-12-01

    Maturation and differentiation of B-cells are driven by T-cells' help through IL-21/STAT3 axis in GC centers or through extrafollicular pathways, in a T-independent manner. B-cell differentiation is defective in common variable immunodeficiency disease (CVID) patients. We investigated if IL-21/STAT3 axis alterations could influence B-cell fate. We activated purified CVID B-cells with surrogate T-dependent (anti-CD40), T-independent (TLR-9 ligand) stimuli or through B-cell receptor engagement (anti-IgM) with or without IL-21. IL-21 mediated STAT3 activation was greater on CD27(-) than CD27(+) B-cells depending on the stimulus. IL-21 alone induced STAT3 phosphorylation (pSTAT3) only on CD27(-) B-cells and IL-21 induced higher pSTAT3 levels on CD27(-) than CD27(+) B-cells after anti-IgM or anti-CD40 activation. CVID CD27(+) B-cells showed selective STAT3 hyperphosphorylation after activation with anti-IgM or anti-CD40 alone and anti-IgM, anti-CD40 or ODN combined with IL-21. Increased STAT3 activation during immune responses could result in B-cell differentiation defects in CVID.

  15. 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 TNFα 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

  16. STAT3 inhibition is a therapeutic strategy for ABC-like diffuse large B-cell lymphoma.

    PubMed

    Scuto, Anna; Kujawski, Maciej; Kowolik, Claudia; Krymskaya, Ludmila; Wang, Lin; Weiss, Lawrence M; Digiusto, David; Yu, Hua; Forman, Stephen; Jove, Richard

    2011-05-01

    Persistent STAT3 signaling contributes to malignant progression in many diverse types of human cancer. STAT3 is constitutively active in activated B-cell (ABC)-like diffuse large B-cell lymphomas (DLBCL), a class of nongerminal center derived DLBCL cells for which existing therapy is weakly effective. In this report, we provide a preclinical proof of concept that STAT3 is an effective molecular target for ABC-like DLBCL therapy. Direct inhibition of STAT3 with short hairpin RNA suppressed the growth of human ABC-like DLBCL in mouse models in a manner associated with apoptosis, repression of STAT3 target genes, and inhibition of a tumor-promoting microenvironment. Together, these results suggest that STAT3 is essential to maintain the pathophysiology of ABC-like DLBCL and therefore that STAT3 inhibition may offer a promising approach in its therapy.

  17. Hyperactivation of STAT3 is involved in abnormal differentiation of dendritic cells in cancer.

    PubMed

    Nefedova, Yulia; Huang, Mei; Kusmartsev, Sergei; Bhattacharya, Raka; Cheng, Pingyan; Salup, Raoul; Jove, Richard; Gabrilovich, Dmitry

    2004-01-01

    Abnormal differentiation of myeloid cells is one of the hallmarks of cancer. However, the molecular mechanisms of this process remain elusive. In this study, we investigated the effect of tumor-derived factors on Janus kinase (Jak)/STAT signaling in myeloid cells during their differentiation into dendritic cells. Tumor cell conditioned medium induced activation of Jak2 and STAT3, which was associated with an accumulation of immature myeloid cells. Jak2/STAT3 activity was localized primarily in these myeloid cells, which prevented the differentiation of immature myeloid cells into mature dendritic cells. This differentiation was restored after removal of tumor-derived factors. Inhibition of STAT3 abrogated the negative effects of these factors on myeloid cell differentiation, and overexpression of STAT3 reproduced the effects of tumor-derived factors. Thus, this is a first demonstration that tumor-derived factors may affect myeloid cell differentiation in cancer via constitutive activation of Jak2/STAT3.

  18. DIESEL EXHAUST PARTICULATE (DEP)-INDUCED ACTIV ATION OF STAT3 REQUIRES ACTIVITIES OF EGFR AND SRC IN AIRWAY EPITHELIAL CELLS

    EPA Science Inventory

    In vivo exposure to diesel exhaust particles (DEP) elicits acute inflammatory responses in the lung characterized by inflammatory cell influx and elevated expression of mediators such as cytokines, and chemokines. Signal transducers and activators of transcription (STAT) protein...

  19. Mitochondrial STAT3 contributes to transformation of Barrett's epithelial cells that express oncogenic Ras in a p53-independent fashion.

    PubMed

    Yu, Chunhua; Huo, Xiaofang; Agoston, Agoston T; Zhang, Xi; Theiss, Arianne L; Cheng, Edaire; Zhang, Qiuyang; Zaika, Alexander; Pham, Thai H; Wang, David H; Lobie, Peter E; Odze, Robert D; Spechler, Stuart J; Souza, Rhonda F

    2015-08-01

    Metaplastic epithelial cells of Barrett's esophagus transformed by the combination of p53-knockdown and oncogenic Ras expression are known to activate signal transducer and activator of transcription 3 (STAT3). When phosphorylated at tyrosine 705 (Tyr705), STAT3 functions as a nuclear transcription factor that can contribute to oncogenesis. STAT3 phosphorylated at serine 727 (Ser727) localizes in mitochondria, but little is known about mitochondrial STAT3's contribution to carcinogenesis in Barrett's esophagus, which is the focus of this study. We introduced a constitutively active variant of human STAT3 (STAT3CA) into the following: 1) non-neoplastic Barrett's (BAR-T) cells; 2) BAR-T cells with p53 knockdown; and 3) BAR-T cells that express oncogenic H-Ras(G12V). STAT3CA transformed only the H-Ras(G12V)-expressing BAR-T cells (evidenced by loss of contact inhibition, formation of colonies in soft agar, and generation of tumors in immunodeficient mice), and did so in a p53-independent fashion. The transformed cells had elevated levels of both mitochondrial (Ser727) and nuclear (Tyr705) phospho-STAT3. Introduction of a STAT3CA construct with a mutated tyrosine phosphorylation site into H-Ras(G12V)-expressing Barrett's cells resulted in high levels of mitochondrial phospho-STAT3 (Ser727) with little or no nuclear phospho-STAT3 (Tyr705), and the cells still formed tumors in immunodeficient mice. Thus tyrosine phosphorylation of STAT3 is not required for tumor formation in Ras-expressing Barrett's cells. We conclude that mitochondrial STAT3 (Ser727) can contribute to oncogenesis in Barrett's cells that express oncogenic Ras. These findings suggest that agents targeting STAT3 might be useful for chemoprevention in patients with Barrett's esophagus.

  20. 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

    2015-07-01

    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.

  1. Stat3/Cdc25a-dependent cell proliferation promotes embryonic axis extension during zebrafish gastrulation

    PubMed Central

    Sepich, Diane S.

    2017-01-01

    Cell proliferation has generally been considered dispensable for anteroposterior extension of embryonic axis during vertebrate gastrulation. Signal transducer and activator of transcription 3 (Stat3), a conserved controller of cell proliferation, survival and regeneration, is associated with human scoliosis, cancer and Hyper IgE Syndrome. Zebrafish Stat3 was proposed to govern convergence and extension gastrulation movements in part by promoting Wnt/Planar Cell Polarity (PCP) signaling, a conserved regulator of mediolaterally polarized cell behaviors. Here, using zebrafish stat3 null mutants and pharmacological tools, we demonstrate that cell proliferation contributes to anteroposterior embryonic axis extension. Zebrafish embryos lacking maternal and zygotic Stat3 expression exhibit normal convergence movements and planar cell polarity signaling, but transient axis elongation defect due to insufficient number of cells resulting largely from reduced cell proliferation and increased apoptosis. Pharmacologic inhibition of cell proliferation during gastrulation phenocopied axis elongation defects. Stat3 regulates cell proliferation and axis extension in part via upregulation of Cdc25a expression during oogenesis. Accordingly, restoring Cdc25a expression in stat3 mutants partially suppressed cell proliferation and gastrulation defects. During later development, stat3 mutant zebrafish exhibit stunted growth, scoliosis, excessive inflammation, and fail to thrive, affording a genetic tool to study Stat3 function in vertebrate development, regeneration, and disease. PMID:28222105

  2. Inhibition of STAT3 with the Generation 2.5 Antisense Oligonucleotide, AZD9150, Decreases Neuroblastoma Tumorigenicity and Increases Chemosensitivity.

    PubMed

    Odate, Seiichi; Veschi, Veronica; Yan, Shuang; Lam, Norris; Woessner, Richard; Thiele, Carol J

    2017-04-01

    Purpose: Neuroblastoma is a pediatric tumor of peripheral sympathoadrenal neuroblasts. The long-term event-free survival of children with high-risk neuroblastoma is still poor despite the improvements with current multimodality treatment protocols. Activated JAK/STAT3 pathway plays an important role in many human cancers, suggesting that targeting STAT3 is a promising strategy for treating high-risk neuroblastoma.Experimental Design: To evaluate the biologic consequences of specific targeting of STAT3 in neuroblastoma, we assessed the effect of tetracycline (Tet)-inducible STAT3 shRNA and the generation 2.5 antisense oligonucleotide AZD9150 which targets STAT3 in three representative neuroblastoma cell line models (AS, NGP, and IMR32).Results: Our data indicated that Tet-inducible STAT3 shRNA and AZD9150 inhibited endogenous STAT3 and STAT3 target genes. Tet-inducible STAT3 shRNA and AZD9150 decreased cell growth and tumorigenicity. In vivo, STAT3 inhibition by Tet-inducible STAT3 shRNA or AZD9150 alone had little effect on growth of established tumors. However, when treated xenograft tumor cells were reimplanted into mice, there was a significant decrease in secondary tumors in the mice receiving AZD9150-treated tumor cells compared with the mice receiving ntASO-treated tumor cells. This indicates that inhibition of STAT3 decreases the tumor-initiating potential of neuroblastoma cells. Furthermore, inhibition of STAT3 significantly increased neuroblastoma cell sensitivity to cisplatin and decreased tumor growth and increased the survival of tumor-bearing mice in vivoConclusions: Our study supports the development of strategies targeting STAT3 inhibition in combination with conventional chemotherapy for patients with high-risk neuroblastoma. Clin Cancer Res; 23(7); 1771-84. ©2016 AACR.

  3. Abnormal repression of SHP-1, SHP-2 and SOCS-1 transcription sustains the activation of the JAK/STAT3 pathway and the progression of the disease in multiple myeloma

    PubMed Central

    Skouri, Nour; Ben Ali, Cyrine; Safra, Ines; Abdelkefi, Abderrahman; Ladeb, Saloua; Mrad, Karima; Ben Othman, Tarek; Ben Ahmed, Mélika

    2017-01-01

    Sustained activation of JAK/STAT3 signaling pathway is classically described in Multiple Myeloma (MM). One explanation could be the silencing of the JAK/STAT suppressor genes, through the hypermethylation of SHP-1 and SOCS-1, previously demonstrated in MM cell lines or in whole bone marrow aspirates. The link between such suppressor gene silencing and the degree of bone marrow invasion or the treatment response has not been evaluated in depth. Using real-time RT-PCR, we studied the expression profile of three JAK/STAT suppressor genes: SHP-1, SHP-2 and SOCS-1 in plasma cells freshly isolated from the bone marrows of MM patients and healthy controls. Our data demonstrated an abnormal repression of such genes in malignant plasma cells and revealed a significant correlation between such defects and the sustained activation of the JAK/STAT3 pathway during MM. The repressed expression of SHP-1 and SHP-2 correlated significantly with a high initial degree of bone marrow infiltration but was, unexpectedly, associated with a better response to the induction therapy. Collectively, our data provide new evidences that substantiate the contribution of JAK/STAT suppressor genes in the pathogenesis of MM. They also highlight the possibility that the decreased gene expression of SHP-1 and SHP-2 could be of interest as a new predictive factor of a favorable treatment response, and suggest new potential mechanisms of action of the therapeutic molecules. Whether such defect helps the progression of the disease from monoclonal gammopathy of unknown significance to MM remains, however, to be determined. PMID:28369102

  4. Arctigenin enhances chemosensitivity of cancer cells to cisplatin through inhibition of the STAT3 signaling pathway.

    PubMed

    Yao, Xiangyang; Zhu, Fenfen; Zhao, Zhihui; Liu, Chang; Luo, Lan; Yin, Zhimin

    2011-10-01

    Arctigenin is a dibenzylbutyrolactone lignan isolated from Bardanae fructus, Arctium lappa L, Saussureamedusa, Torreya nucifera, and Ipomea cairica. It has been reported to exhibit anti-inflammatory activities, which is mainly mediated through its inhibitory effect on nuclear transcription factor-kappaB (NF-κB). But the role of arctigenin in JAK-STAT3 signaling pathways is still unclear. In present study, we investigated the effect of arctigenin on signal transducer and activator of transcription 3 (STAT3) pathway and evaluated whether suppression of STAT3 activity by arctigenin could sensitize cancer cells to a chemotherapeutic drug cisplatin. Our results show that arctigenin significantly suppressed both constitutively activated and IL-6-induced STAT3 phosphorylation and subsequent nuclear translocation in cancer cells. Inhibition of STAT3 tyrosine phosphorylation was found to be achieved through suppression of Src, JAK1, and JAK2, while suppression of STAT3 serine phosphorylation was mediated by inhibition of ERK activation. Pervanadate reversed the arctigenin-induced downregulation of STAT3 activation, suggesting the involvement of a protein tyrosine phosphatase. Indeed, arctigenin can obviously induce the expression of the PTP SHP-2. Furthermore, the constitutive activation level of STAT3 was found to be correlated to the resistance of cancer cells to cisplatin-induced apoptosis. Arctigenin dramatically promoted cisplatin-induced cell death in cancer cells, indicating that arctigenin enhanced the sensitivity of cancer cells to cisplatin mainly via STAT3 suppression. These observations suggest a novel anticancer function of arctigenin and a potential therapeutic strategy of using arctigenin in combination with chemotherapeutic agents for cancer treatment.

  5. 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

  6. STAT5 Outcompetes STAT3 To Regulate the Expression of the Oncogenic Transcriptional Modulator BCL6

    PubMed Central

    Walker, Sarah R.; Nelson, Erik A.; Yeh, Jennifer E.; Pinello, Luca; Yuan, Guo-Cheng

    2013-01-01

    Inappropriate activation of the transcription factors STAT3 and STAT5 has been shown to drive cancer pathogenesis through dysregulation of genes involved in cell survival, growth, and differentiation. Although STAT3 and STAT5 are structurally related, they can have opposite effects on key genes, including BCL6. BCL6, a transcriptional repressor, has been shown to be oncogenic in diffuse large B cell lymphoma. BCL6 also plays an important role in breast cancer pathogenesis, a disease in which STAT3 and STAT5 can be activated individually or concomitantly. To determine the mechanism by which these oncogenic transcription factors regulate BCL6 transcription, we analyzed their effects at the levels of chromatin and gene expression. We found that STAT3 increases expression of BCL6 and enhances recruitment of RNA polymerase II phosphorylated at a site associated with transcriptional initiation. STAT5, in contrast, represses BCL6 expression below basal levels and decreases the association of RNA polymerase II at the gene. Furthermore, the repression mediated by STAT5 is dominant over STAT3-mediated induction. STAT5 exerts this effect by displacing STAT3 from one of the two regulatory regions to which it binds. These findings may underlie the divergent biology of breast cancers containing activated STAT3 alone or in conjunction with activated STAT5. PMID:23716595

  7. How should we define STAT3 as an oncogene and as a potential target for therapy?

    PubMed

    Sellier, Hélène; Rébillard, Amélie; Guette, Catherine; Barré, Benjamin; Coqueret, Olivier

    2013-07-01

    Aberrant activation of the STAT3 transcription factor has been reported in a large group of tumors and a strong biological basis now defines this protein as an oncogenic driver. Consequently, STAT3 is considered to be a promising target in the field of cancer therapy. For its inhibition to result in a successful therapeutic approach, the definition of a target tumor population identified by specific and detectable alterations is critical. The canonical activation model of STAT3 relies on a constitutive phosphorylation on its 705 tyrosine site, resulting in its dimerization, nuclear translocation, and the consequent activation of cancer genes. Therefore, it is expected that tumors expressing this phosphorylated form are addicted to STAT3 and will be sensitive to existing drugs which are targeting this dimeric form. However, recent results have shown that STAT3 can function as an oncogene in the absence of this tyrosine phosphorylation. This indicates that different forms of the transcription factor also play an important role in tumor growth and chemotherapy resistance. This complicates the definition of STAT3 as an oncogene and as a potential prognosis and predictive biomarker. The obligation to target a defined tumor type implies that future clinical trials should use a precise definition of STAT3 activation. This will allow tumors addicted to this oncogene to be identified correctly, leading to a strong rationale for patient stratification.

  8. STAT3 modulates β-cell cycling in injured mouse pancreas and protects against DNA damage

    PubMed Central

    De Groef, S; Renmans, D; Cai, Y; Leuckx, G; Roels, S; Staels, W; Gradwohl, G; Baeyens, L; Heremans, Y; Martens, G A; De Leu, N; Sojoodi, M; Van de Casteele, M; Heimberg, H

    2016-01-01

    Partial pancreatic duct ligation (PDL) of mouse pancreas induces a doubling of the β-cell mass mainly through proliferation of pre-existing and newly formed β-cells. The molecular mechanism governing this process is still largely unknown. Given the inflammatory nature of PDL and inflammation-induced signaling via the signal transducer and activator of transcription 3 (STAT3), the activation and the role of STAT3 in PDL-induced β-cell proliferation were investigated. Duct ligation stimulates the expression of several cytokines that can act as ligands inducing STAT3 signaling and phosphorylation in β-cells. β-Cell cycling increased by conditional β-cell-specific Stat3 knockout and decreased by STAT3 activation through administration of interleukin-6. In addition, the level of DNA damage in β-cells of PDL pancreas increased after deletion of Stat3. These data indicate a role for STAT3 in maintaining a steady state in the β-cell, by modulating its cell cycle and protection from DNA damage. PMID:27336716

  9. Aberrant LPL Expression, Driven by STAT3, Mediates Free Fatty Acid Metabolism in CLL Cells

    PubMed Central

    Rozovski, Uri; Grgurevic, Srdana; Bueso-Ramos, Carlos; Harris, David M.; Li, Ping; Liu, Zhiming; Wu, Ji Yuan; Jain, Preetesh; Wierda, William; Burger, Jan; O’Brien, Susan; Jain, Nitin; Ferrajoli, Alessandra; Keating, Michael J.; Estrov, Zeev

    2015-01-01

    While reviewing chronic lymphocytic leukemia (CLL) bone marrow slides we identified cytoplasmic lipid vacuoles in CLL cells but not in normal B cells. Because lipoprotein lipase (LPL), which catalyzes hydrolysis of triglycerides into free fatty acids (FFAs), is aberrantly expressed in CLL, we investigated whether LPL regulates the oxidative metabolic capacity of CLL cells. We found that unlike normal B cells, CLL cells metabolize FFAs. Because STAT3 is constitutively activated in CLL cells and because we identified putative STAT3 binding sites in the LPL promoter, we sought to determine whether STAT3 drives the aberrant expression of LPL. Transfection of luciferase reporter gene constructs driven by LPL promoter fragments into MM1 cells revealed that STAT3 activates the LPL promoter. In addition, chromatin immunoprecipitation (ChIP) confirmed that STAT3 binds to the LPL promoter. Furthermore, transfection of CLL cells with STAT3-shRNA downregulated LPL transcripts and protein levels, confirming that STAT3 activates the LPL gene. Finally, transfection of CLL cells with LPL-siRNAs decreased the capacity of CLL cells to oxidize FFAs and reduced cell viability. PMID:25733697

  10. Methanethiosulfonate derivatives as ligands of the STAT3-SH2 domain.

    PubMed

    Gabriele, Elena; Ricci, Chiara; Meneghetti, Fiorella; Ferri, Nicola; Asai, Akira; Sparatore, Anna

    2017-12-01

    With the aim to discover new STAT3 direct inhibitors, potentially useful as anticancer agents, a set of methanethiosulfonate drug hybrids were synthesized. The in vitro tests showed that all the thiosulfonic compounds were able to strongly and selectively bind STAT3-SH2 domain, whereas the parent drugs were completely devoid of this ability. In addition, some of them showed a moderate antiproliferative activity on HCT-116 cancer cell line. These results suggest that methanethiosulfonate moiety can be considered a useful scaffold in the preparation of new direct STAT3 inhibitors. Interestingly, an unusual kind of organo-sulfur derivative, endowed with valuable antiproliferative activity, was occasionally isolated. [Formula: see text].

  11. Loss of androgen receptor expression promotes a stem-like cell phenotype in prostate cancer through STAT3 signaling.

    PubMed

    Schroeder, Anne; Herrmann, Andreas; Cherryholmes, Gregory; Kowolik, Claudia; Buettner, Ralf; Pal, Sumanta; Yu, Hua; Müller-Newen, Gerhard; Jove, Richard

    2014-02-15

    Androgen receptor (AR) signaling is important for prostate cancer progression. However, androgen-deprivation and/or AR targeting-based therapies often lead to resistance. Here, we demonstrate that loss of AR expression results in STAT3 activation in prostate cancer cells. AR downregulation further leads to development of prostate cancer stem-like cells (CSC), which requires STAT3. In human prostate tumor tissues, elevated cancer stem-like cell markers coincide with those cells exhibiting high STAT3 activity and low AR expression. AR downregulation-induced STAT3 activation is mediated through increased interleukin (IL)-6 expression. Treating mice with soluble IL-6 receptor fusion protein or silencing STAT3 in tumor cells significantly reduced prostate tumor growth and CSCs. Together, these findings indicate an opposing role of AR and STAT3 in prostate CSC development.

  12. Role of STAT3 in Transformation and Drug Resistance in CML

    PubMed Central

    Nair, Rajesh R.; Tolentino, Joel H.; Hazlehurst, Lori A.

    2012-01-01

    Chronic myeloid leukemia (CML) is initially driven by the bcr–abl fusion oncoprotein. The identification of bcr–abl led to the discovery and rapid translation into the clinic of bcr–abl kinase inhibitors. Although, bcr–abl inhibitors are efficacious, experimental evidence indicates that targeting bcr–abl is not sufficient for elimination of minimal residual disease found within the bone marrow (BM). Experimental evidence indicates that the failure to eliminate the leukemic stem cell contributes to persistent minimal residual disease. Thus curative strategies will likely need to focus on strategies where bcr–abl inhibitors are given in combination with agents that specifically target the leukemic stem cell or the leukemic stem cell niche. One potential target to be exploited is the Janus kinase (JAK)/signal transducers and activators of transcription 3 (STAT3) pathway. Recently using STAT3 conditional knock-out mice it was shown that STAT3 is critical for initiating the disease. Interestingly, in the absence of treatment, STAT3 was not shown to be required for maintenance of the disease, suggesting that STAT3 is required only in the tumor initiating stem cell population (Hoelbl et al., 2010). In the context of the BM microenvironment, STAT3 is activated in a bcr–abl independent manner by the cytokine milieu. Activation of JAK/STAT3 was shown to contribute to cell survival even in the event of complete inhibition of bcr–abl activity within the BM compartment. Taken together, these studies suggest that JAK/STAT3 is an attractive therapeutic target for developing strategies for targeting the JAK–STAT3 pathway in combination with bcr–abl kinase inhibitors and may represent a viable strategy for eliminating or reducing minimal residual disease located in the BM in CML. PMID:22649784

  13. STAT3 Undergoes Acetylation-dependent Mitochondrial Translocation to Regulate Pyruvate Metabolism

    PubMed Central

    Xu, Yan S.; Liang, Jinyuan J.; Wang, Yumei; Zhao, Xiang-zhong J.; Xu, Li; Xu, Ye-yang; Zou, Quanli C.; Zhang, Junxun M.; Tu, Cheng-e; Cui, Yan-ge; Sun, Wei-hong; Huang, Chao; Yang, Jing-hua; Chin, Y. Eugene

    2016-01-01

    Cytoplasmic STAT3, after activation by growth factors, translocates to different subcellular compartments, including nuclei and mitochondria, where it carries out different biological functions. However, the precise mechanism by which STAT3 undergoes mitochondrial translocation and subsequently regulates the tricarboxylic acid (TCA) cycle-electron transport chain (ETC) remains poorly understood. Here, we clarify this process by visualizing STAT3 acetylation in starved cells after serum reintroduction or insulin stimulation. CBP-acetylated STAT3 undergoes mitochondrial translocation in response to serum introduction or insulin stimulation. In mitochondria, STAT3 associates with the pyruvate dehydrogenase complex E1 (PDC-E1) and subsequently accelerates the conversion of pyruvate to acetyl-CoA, elevates the mitochondrial membrane potential, and promotes ATP synthesis. SIRT5 deacetylates STAT3, thereby inhibiting its function in mitochondrial pyruvate metabolism. In the A549 lung cancer cell line, constitutively acetylated STAT3 localizes to mitochondria, where it maintains the mitochondrial membrane potential and ATP synthesis in an active state. PMID:28004755

  14. IL-17 induces EMT via Stat3 in lung adenocarcinoma

    PubMed Central

    Huang, Qi; Han, Jieli; Fan, Jinshuo; Duan, Limin; Guo, Mengfei; Lv, Zhilei; Hu, Guorong; Chen, Lian; Wu, Feng; Tao, Xiaonan; Xu, Juanjuan; Jin, Yang

    2016-01-01

    Epithelial-mesenchymal transition (EMT) plays a vital role in lung inflammatory diseases, including lung cancer. However, the role and mechanism of action of the proinflammatory cytokine IL-17 in EMT in lung adenocarcinoma remain unresolved. In our study, we discovered that the expression of N-cadherin, Vimentin, Snail1, Snail2, and Twist1 was positively correlated with IL-17 expression, while E-cadherin expression was negatively correlated with IL-17 expression in human lung adenocarcinoma tissues. Moreover, we confirmed that IL-17 promoted EMT in A549 and Lewis lung carcinoma (LLC) cells in vitro by upregulating N-cadherin, Vimentin, Snail1, Snail2, and Twist1 expression and downregulating E-cadherin expression. Stat3 was activated in IL-17-treated A549 and LLC cells, and Stat3 inhibition or siRNA knockdown notably reduced IL-17-induced EMT in A549 and LLC cells. Thus, IL-17 promotes EMT in lung adenocarcinoma via Stat3 signaling; these observations suggest that targeting IL-17 and EMT are potential novel therapeutic strategies for lung cancer. PMID:27186414

  15. STAT3 Induction of MiR-146b Forms a Feedback Loop to Inhibit the NF-κB 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 κB (NF-κB)-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-κB relevant to constitutive STAT3 activation in malignancy and the role of inflammation in oncogenesis. PMID:24473196

  16. Pivotal Importance of STAT3 in Protecting the Heart from Acute and Chronic Stress: New Advancement and Unresolved Issues

    PubMed Central

    Zouein, Fouad A.; Altara, Raffaele; Chen, Qun; Lesnefsky, Edward J.; Kurdi, Mazen; Booz, George W.

    2015-01-01

    The transcription factor, signal transducer and activator of transcription 3 (STAT3), has been implicated in protecting the heart from acute ischemic injury under both basal conditions and as a crucial component of pre- and post-conditioning protocols. A number of anti-oxidant and antiapoptotic genes are upregulated by STAT3 via canonical means involving phosphorylation on Y705 and S727, although other incompletely defined posttranslational modifications are involved. In addition, STAT3 is now known to be present in cardiac mitochondria and to exert actions that regulate the electron transport chain, reactive oxygen species production, and mitochondrial permeability transition pore opening. These non-canonical actions of STAT3 are enhanced by S727 phosphorylation. The molecular basis for the mitochondrial actions of STAT3 is poorly understood, but STAT3 is known to interact with a critical subunit of complex I and to regulate complex I function. Dysfunctional complex I has been implicated in ischemic injury, heart failure, and the aging process. Evidence also indicates that STAT3 is protective to the heart under chronic stress conditions, including hypertension, pregnancy, and advanced age. Paradoxically, the accumulation of unphosphorylated STAT3 (U-STAT3) in the nucleus has been suggested to drive pathological cardiac hypertrophy and inflammation via non-canonical gene expression, perhaps involving a distinct acetylation profile. U-STAT3 may also regulate chromatin stability. Our understanding of how the non-canonical genomic and mitochondrial actions of STAT3 in the heart are regulated and coordinated with the canonical actions of STAT3 is rudimentary. Here, we present an overview of what is currently known about the pleotropic actions of STAT3 in the heart in order to highlight controversies and unresolved issues. PMID:26664907

  17. Roles of STAT3 in Protein Secretion Pathways during the Acute-Phase Response

    PubMed Central

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

    2013-01-01

    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-κB, 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

  18. Early-onset lymphoproliferation and autoimmunity caused by germline STAT3 gain-of-function mutations.

    PubMed

    Milner, Joshua D; Vogel, Tiphanie P; Forbes, Lisa; Ma, Chi A; Stray-Pedersen, Asbjørg; Niemela, Julie E; Lyons, Jonathan J; Engelhardt, Karin R; Zhang, Yu; Topcagic, Nermina; Roberson, Elisha D O; Matthews, Helen; Verbsky, James W; Dasu, Trivikram; Vargas-Hernandez, Alexander; Varghese, Nidhy; McClain, Kenneth L; Karam, Lina B; Nahmod, Karen; Makedonas, George; Mace, Emily M; Sorte, Hanne S; Perminow, Gøri; Rao, V Koneti; O'Connell, Michael P; Price, Susan; Su, Helen C; Butrick, Morgan; McElwee, Joshua; Hughes, Jason D; Willet, Joseph; Swan, David; Xu, Yaobo; Santibanez-Koref, Mauro; Slowik, Voytek; Dinwiddie, Darrell L; Ciaccio, Christina E; Saunders, Carol J; Septer, Seth; Kingsmore, Stephen F; White, Andrew J; Cant, Andrew J; Hambleton, Sophie; Cooper, Megan A

    2015-01-22

    Germline loss-of-function mutations in the transcription factor signal transducer and activator of transcription 3 (STAT3) cause immunodeficiency, whereas somatic gain-of-function mutations in STAT3 are associated with large granular lymphocytic leukemic, myelodysplastic syndrome, and aplastic anemia. Recently, germline mutations in STAT3 have also been associated with autoimmune disease. Here, we report on 13 individuals from 10 families with lymphoproliferation and early-onset solid-organ autoimmunity associated with 9 different germline heterozygous mutations in STAT3. Patients exhibited a variety of clinical features, with most having lymphadenopathy, autoimmune cytopenias, multiorgan autoimmunity (lung, gastrointestinal, hepatic, and/or endocrine dysfunction), infections, and short stature. Functional analyses demonstrate that these mutations confer a gain-of-function in STAT3 leading to secondary defects in STAT5 and STAT1 phosphorylation and the regulatory T-cell compartment. Treatment targeting a cytokine pathway that signals through STAT3 led to clinical improvement in 1 patient, suggesting a potential therapeutic option for such patients. These results suggest that there is a broad range of autoimmunity caused by germline STAT3 gain-of-function mutations, and that hematologic autoimmunity is a major component of this newly described disorder. Some patients for this study were enrolled in a trial registered at www.clinicaltrials.gov as #NCT00001350.

  19. Mitochondrial Stat3, the Need for Design Thinking

    PubMed Central

    Yang, Rui; Rincon, Mercedes

    2016-01-01

    Stat3 has been studied extensively as a transcription factor, however the finding that Stat3 also localizes to mitochondria has opened a new area to discover non-classical functions. Here we review the current knowledge of mitochondrial Stat3 as a regulator of the electron transport chain (ETC) and its impact on mitochondrial production of ATP and ROS. We also describe recent findings identifying Stat3 as a regulator of mitochondrial Ca2+ homeostasis through its effect on the ETC. It is becoming evident that these non-classical functions of Stat3 can have a major impact on cancer progression, cardiovascular diseases, and inflammatory diseases. Therefore, mitochondrial Stat3 functions challenge the current design of therapies that solely target Stat3 as a transcription factor and suggest the need for “design thinking,” which leads to the development of novel strategies, to intervene the Stat3 pathway. PMID:27019635

  20. MicroRNA-124 suppresses growth of human hepatocellular carcinoma by targeting STAT3

    SciTech Connect

    Lu, Yanxin; Yue, Xupeng; Cui, Yuanyuan; Zhang, Jufeng; Wang, KeWei

    2013-11-29

    Highlights: •miR-124 is down-regulated in hepatocellular carcinoma HepG2 cells. •Over-expression of miR-124 suppresses proliferation and induces apoptosis in HepG2 cells. •miR-124 inhibits xenograft tumor growth in nude mice implanted with HepG2 cells by reducing STAT3 expression. •STATs function as a novel target of miR-124 in HCC HepG2 cells. -- Abstract: The aberrant expression of microRNAs is associated with development and progression of cancers. Down-regulation of miR-124 has been demonstrated in the hepatocellular carcinoma (HCC), but the underlying mechanism by which miR-124 suppresses tumorigenesis in HCC remains elusive. In this study, we found that miR-124 suppresses the tumor growth of HCC through targeting the signal transducers and activators of transcription 3 (STAT3). Overexpression of miR-124 suppressed proliferation and induced apoptosis in HepG-2 cells. Luciferase assay confirmed that miR-124 binding to the 3′-UTR region of STAT3 inhibited the expression of STAT3 and phosphorylated STAT3 proteins in HepG-2 cells. Knockdown of STAT3 by siRNA in HepG-2 cells mimicked the effect induced by miR-124. Overexpression of STAT3 in miR-124-transfected HepG-2 cells effectively rescued the inhibition of cell proliferation caused by miR-124. Furthermore, miR-124 suppressed xenograft tumor growth in nude mice implanted with HepG-2 cells by reducing STAT3 expression. Taken together, our findings show that miR-124 functions as tumor suppressor in HCC by targeting STAT3, and miR-124 may therefore serve as a biomarker for diagnosis and therapeutics in HCC.

  1. STATs in cancer inflammation and immunity: a leading role for STAT3.

    PubMed

    Yu, Hua; Pardoll, Drew; Jove, Richard

    2009-11-01

    Commensurate with their roles in regulating cytokine-dependent inflammation and immunity, signal transducer and activator of transcription (STAT) proteins are central in determining whether immune responses in the tumour microenvironment promote or inhibit cancer. Persistently activated STAT3 and, to some extent, STAT5 increase tumour cell proliferation, survival and invasion while suppressing anti-tumour immunity. The persistent activation of STAT3 also mediates tumour-promoting inflammation. STAT3 has this dual role in tumour inflammation and immunity by promoting pro-oncogenic inflammatory pathways, including nuclear factor-kappaB (NF-kappaB) and interleukin-6 (IL-6)-GP130-Janus kinase (JAK) pathways, and by opposing STAT1- and NF-kappaB-mediated T helper 1 anti-tumour immune responses. Consequently, STAT3 is a promising target to redirect inflammation for cancer therapy.

  2. Interplay of hepatic and myeloid STAT3 in facilitating liver regeneration via tempering innate immunity

    PubMed Central

    Wang, Hua; Park, Ogyi; Lafdil, Fouad; Shen, Kezhen; Horiguchi, Norio; Yin, Shi; Fu, Xin-Yuan; Kunos, George; Gao, Bin

    2009-01-01

    Liver regeneration triggered by 2/3 partial hepatectomy is accompanied by elevated hepatic levels of endotoxin, which contributes to the regenerative process, but liver inflammation and apoptosis remain paradoxically limited. Here we show that STAT3, an important anti-inflammatory signal, is activated in myeloid cells after partial hepatectomy and its conditional deletion results in an enhanced inflammatory response. Surprisingly, this is accompanied by an improved rather than impaired regenerative response with increased hepatic STAT3 activation, which may contribute to the enhanced liver regeneration. Indeed, conditional deletion of STAT3 in both hepatocytes and myeloid cells results in elevated activation of STAT1 and apoptosis of hepatocytes, and a dramatic reduction in survival after partial hepatectomy, whereas additional global deletion of STAT1 protects against these effects. Conclusions: An interplay of myeloid and hepatic STAT3 signaling is essential to prevent liver failure during liver regeneration through tempering a strong innate inflammatory response mediated by STAT1 signaling. PMID:20041412

  3. STATs in cancer inflammation and immunity: a leading role for STAT3

    PubMed Central

    Yu, Hua; Pardoll, Drew; Jove, Richard

    2016-01-01

    Commensurate with their roles in regulating cytokine-dependent inflammation and immunity, signal transducer and activator of transcription (STAT) proteins are central in determining whether immune responses in the tumour microenvironment promote or inhibit cancer. Persistently activated STAT3 and, to some extent, STAT5 increase tumour cell proliferation, survival and invasion while suppressing anti-tumour immunity. The persistent activation of STAT3 also mediates tumour-promoting inflammation. STAT3 has this dual role in tumour inflammation and immunity by promoting pro-oncogenic inflammatory pathways, including nuclear factor-κB (NF-κB) and interleukin-6 (IL-6)–GP130–Janus kinase (JAK) pathways, and by opposing STAT1- and NF-κB-mediated T helper 1 anti-tumour immune responses. Consequently, STAT3 is a promising target to redirect inflammation for cancer therapy. PMID:19851315

  4. Decreased STAT3 Phosphorylation Mediates Cell Swelling in Ammonia-Treated Astrocyte Cultures

    PubMed Central

    Jayakumar, Arumugam R.; Curtis, Kevin M.; Panickar, Kiran S.; Shamaladevi, Nagarajarao; Norenberg, Michael D.

    2016-01-01

    Brain edema, due largely to astrocyte swelling, and the subsequent increase in intracranial pressure and brain herniation, are major complications of acute liver failure (ALF). Elevated level of brain ammonia has been strongly implicated in the development of astrocyte swelling associated with ALF. The means by which ammonia brings about astrocyte swelling, however, is incompletely understood. Recently, oxidative/nitrosative stress and associated signaling events, including activation of mitogen-activated protein kinases (MAPKs), as well as activation of the transcription factor, nuclear factor-kappaB (NF-κB), have been implicated in the mechanism of ammonia-induced astrocyte swelling. Since these signaling events are known to be regulated by the transcription factor, signal transducer and activator of transcription 3 (STAT3), we examined the state of STAT3 activation in ammonia-treated cultured astrocytes, and determined whether altered STAT3 activation and/or protein expression contribute to the ammonia-induced astrocyte swelling. STAT3 was found to be dephosphorylated (inactivated) at Tyrosine705 in ammonia-treated cultured astrocytes. Total STAT3 protein level was also reduced in ammonia-treated astrocytes. We also found a significant increase in protein tyrosine phosphatase receptor type-1 (PTPRT-1) protein expression in ammonia-treated cultured astrocytes, and that inhibition of PTPRT-1 enhanced the phosphorylation of STAT3 after ammonia treatment. Additionally, exposure of cultured astrocytes to inhibitors of protein tyrosine phosphatases diminished the ammonia-induced cell swelling, while cultured astrocytes over-expressing STAT3 showed a reduction in the astrocyte swelling induced by ammonia. Collectively, these studies strongly suggest that inactivation of STAT3 represents a critical event in the mechanism of the astrocyte swelling associated with acute liver failure. PMID:27918421

  5. 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

  6. Mitochondrial STAT3 and reactive oxygen species: A fulcrum of adipogenesis?

    PubMed Central

    Kramer, Adam H; Kadye, Rose; Houseman, Pascalene S; Prinsloo, Earl

    2015-01-01

    The balance between cellular lineages can be controlled by reactive oxygen species (ROS). Cellular differentiation into adipocytes is highly dependent on the production of ROS to initiate the process through activation of multiple interlinked factors that stimulate mitotic clonal expansion and cellular maturation. The signal transducer and activator of transcription family of signaling proteins have accepted roles in adipogenesis and associated lipogenesis. Non-canonical mitochondrial localization of STAT3 and other members of the STAT family however opens up new avenues for investigation of its role in the aforementioned processes. Following recent observations of differences in mitochondrially localized serine 727 phosphorylated STAT3 (mtSTAT3-pS727) in preadipocytes and adipocytes, here, we hypothesize and speculate further on the role of mitochondrial STAT3 in adipogenesis. PMID:27127727

  7. Regulation of Natural Killer Cell Function by STAT3

    PubMed Central

    Cacalano, Nicholas A.

    2016-01-01

    Natural killer (NK) cells, key members of a distinct hematopoietic lineage, innate lymphoid cells, are not only critical effectors that mediate cytotoxicity toward tumor and virally infected cells but also regulate inflammation, antigen presentation, and the adaptive immune response. It has been shown that NK cells can regulate the development and activation of many other components of the immune response, such as dendritic cells, which in turn, modulate the function of NK cells in multiple synergistic feed back loops driven by cell–cell contact, and the secretion of cytokines and chemokines that control effector function and migration of cells to sites of immune activation. The signal transducer and activator of transcription (STAT)-3 is involved in driving almost all of the pathways that control NK cytolytic activity as well as the reciprocal regulatory interactions between NK cells and other components of the immune system. In the context of tumor immunology, NK cells are a first line of defense that eliminates pre-cancerous and transformed cells early in the process of carcinogenesis, through a mechanism of “immune surveillance.” Even after tumors become established, NK cells are critical components of anticancer immunity: dysfunctional NK cells are often found in the peripheral blood of cancer patients, and the lack of NK cells in the tumor microenvironment often correlates to poor prognosis. The pathways and soluble factors activated in tumor-associated NK cells, cancer cells, and regulatory myeloid cells, which determine the outcome of cancer immunity, are all critically regulated by STAT3. Using the tumor microenvironment as a paradigm, we present here an overview of the research that has revealed fundamental mechanisms through which STAT3 regulates all aspects of NK cell biology, including NK development, activation, target cell killing, and fine tuning of the innate and adaptive immune responses. PMID:27148255

  8. Rosmarinic acid suppresses colonic inflammation in dextran sulphate sodium (DSS)-induced mice via dual inhibition of NF-κB and STAT3 activation

    PubMed Central

    Jin, Bo-Ram; Chung, Kyung-Sook; Cheon, Se-Yun; Lee, Minho; Hwang, Soonjae; Noh Hwang, Sam; Rhee, Ki-Jong; An, Hyo-Jin

    2017-01-01

    Ulcerative colitis (UC), a type of inflammatory bowel disease (IBD), is a chronic inflammatory disorder of the colon. Although UC is generally treated with anti-inflammatory drugs or immunosuppressants, most of these treatments often prove to be inadequate. Rosmarinic acid (RA) is a phenolic ester included in various medicinal herbs such as Salvia miltiorrhiz and Perilla frutescens. Although RA has many biological and pharmacological activities, the anti-inflammatory effect of RA in colonic tissue remains unclear. In this study, we investigated the anti-inflammatory effects and underlying molecular mechanism of RA in mice with dextran sulphate sodium (DSS)-induced colitis. In the DSS-induced colitis model, RA significantly reduced the severity of colitis, as assessed by disease activity index (DAI) scores, colonic damage, and colon length. In addition, RA resulted in the reduction of the inflammatory-related cytokines, such as IL-6, IL-1β, and IL-22, and protein levels of COX-2 and iNOS in mice with DSS-induced colitis. Furthermore, RA effectively and pleiotropically inhibited nuclear factor-kappa B and signal transducer and activator of transcription 3 activation, and subsequently reduced the activity of pro-survival genes that depend on these transcription factors. These results demonstrate that RA has an ameliorative effect on colonic inflammation and thus a potential therapeutic role in colitis. PMID:28383063

  9. 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; Sayama, Koji

    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.

  10. Targeting Signal Transducers and Activators of Transcription-3 (Stat3) As a Novel Strategy In Sensitizing Breast Cancer To Egfr-Targeted Therapy

    DTIC Science & Technology

    2008-06-01

    transition of the epithelial to the mesenchymal -like phenotype in cultured breast cancer cells . Cancer cells of epithelial origin undergo EMT as...induce epithelial mesenchymal transition by activating expression of TWIST, an E-cadherin repressor. In breast cancer cells with high levels of EGFR...expressing cancer cells to undergo a transition from the epithelial to the spindle-like

  11. Ablation of STAT3 in the B Cell Compartment Restricts Gammaherpesvirus Latency In Vivo

    PubMed Central

    Reddy, Sandeep Steven; Foreman, Hui-Chen Chang; Sioux, Thubten Ozula; Park, Gee Ho; Poli, Valeria; Reich, Nancy C.

    2016-01-01

    ABSTRACT A challenging property of gammaherpesviruses is their ability to establish lifelong persistence. The establishment of latency in B cells is thought to involve active virus engagement of host signaling pathways. Pathogenic effects of these viruses during latency or following reactivation can be devastating to the host. Many cancers, including those associated with members of the gammaherpesvirus family, Kaposi’s sarcoma-associated herpesvirus and Epstein-Barr virus, express elevated levels of active host signal transducer and activator of transcription-3 (STAT3). STAT3 is activated by tyrosine phosphorylation in response to many cytokines and can orchestrate effector responses that include proliferation, inflammation, metastasis, and developmental programming. However, the contribution of STAT3 to gammaherpesvirus pathogenesis remains to be completely understood. This is the first study to have identified STAT3 as a critical host determinant of the ability of gammaherpesvirus to establish long-term latency in an animal model of disease. Following an acute infection, murine gammaherpesvirus 68 (MHV68) established latency in resident B cells, but establishment of latency was dramatically reduced in animals with a B cell-specific STAT3 deletion. The lack of STAT3 in B cells did not impair germinal center responses for immunoglobulin (Ig) class switching in the spleen and did not reduce either total or virus-specific IgG titers. Although ablation of STAT3 in B cells did not have a global effect on these assays of B cell function, it had long-term consequences for the viral load of the host, since virus latency was reduced at 6 to 8 weeks postinfection. Our findings establish host STAT3 as a mediator of gammaherpesvirus persistence. PMID:27486189

  12. CpG-STAT3siRNA for Castration-Resistant Prostate Cancer Therapy

    DTIC Science & Technology

    2015-12-01

    host, likely through activation of host innate immunity. We also verified CpG-STAT3 siRNA efficacy in Ras/Myc oncogene-driven and STAT3-dependent...Kawai T, Akira S (2010) The role of pattern- recognition receptors in innate immunity: update on Toll-like receptors. Nat Immunol 11:373–384 10...Cancer Immunotherapeutics & Tumor Immunology , Beckman Research Institute at City of Hope, Duarte, CA 91010, USA 2Bioinformatics Core Facility, Beckman

  13. Indirubin derivatives inhibit Stat3 signaling and induce apoptosis in human cancer cells.

    PubMed

    Nam, Sangkil; Buettner, Ralf; Turkson, James; Kim, Donghwa; Cheng, Jin Q; Muehlbeyer, Stephan; Hippe, Frankie; Vatter, Sandra; Merz, Karl-Heinz; Eisenbrand, Gerhard; Jove, Richard

    2005-04-26

    Stat3 protein has an important role in oncogenesis and is a promising anticancer target. Indirubin, the active component of a traditional Chinese herbal medicine, has been shown previously to inhibit cyclin-dependent kinases, resulting in cell cycle arrest. Here, we show that the indirubin derivatives E564, E728, and E804 potently block constitutive Stat3 signaling in human breast and prostate cancer cells. In addition, E804 directly inhibits Src kinase activity (IC(50) = 0.43 microM) in an in vitro kinase assay. Levels of tyrosyl phosphorylation of c-Src are also reduced in cultured cells 30 min after E804 treatment. Tyrosyl phosphorylation of Stat3, which is known to be phosphorylated by c-Src, was decreased, and constitutive Stat3 DNA binding-activity was suppressed in cells 30 min after E804 treatment. The antiapoptotic proteins Mcl-1 and Survivin, which are encoded in target genes of Stat3, were down-regulated by indirubin derivatives, followed by induction of apoptosis. These results demonstrate that E804 directly blocks the Src-Stat3 signaling pathway, suggesting that the antitumor activity of indirubin compounds is at least partially due to inhibition of this pathway.

  14. The Anti-inflammatory Activities of Two Major Withanolides from Physalis minima Via Acting on NF-κB, STAT3, and HO-1 in LPS-Stimulated RAW264.7 Cells.

    PubMed

    Li, Rui-Jun; Gao, Cai-Yun; Guo, Chao; Zhou, Miao-Miao; Luo, Jun; Kong, Ling-Yi

    2016-12-02

    Physalis minima has been traditionally used as a folk herbal medicine in China for the treatment of many inflammatory diseases. However, little is known about its anti-inflammatory constituents and associated molecular mechanisms. In our study, withaphysalin A (WA) and 2, 3-dihydro-withaphysalin C (WC), two major withanolide-type compounds, were obtained from the anti-inflammatory fraction of P. minima. Both WA and WC significantly inhibited the production of nitrite oxide (NO), prostaglandin E2 (PGE2), and several pro-inflammatory cytokines, such as interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) in lipopolysaccharide (LPS)-activated RAW264.7 macrophages. Further research indicated that they downregulated the LPS-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the mRNA and protein levels. In addition, they also suppressed nuclear translocation of NF-κB p65, phosphorylation of STAT3, and upregulated HO-1 expression. Intriguingly, the activation of MAPKs was suppressed by WA but was not altered by WC. Taken together, these data provide scientific evidence for elucidating the major bioactive constituents and related molecular mechanisms for the traditional use of P. minima and suggest that WA and WC can be attractive therapeutic candidates for various inflammatory diseases.

  15. Serum-resistant CpG-STAT3 decoy for targeting survival and immune checkpoint signaling in acute myeloid leukemia.

    PubMed

    Zhang, Qifang; Hossain, Dewan Md Sakib; Duttagupta, Priyanka; Moreira, Dayson; Zhao, Xingli; Won, Haejung; Buettner, Ralf; Nechaev, Sergey; Majka, Marcin; Zhang, Bin; Cai, Qi; Swiderski, Piotr; Kuo, Ya-Huei; Forman, Stephen; Marcucci, Guido; Kortylewski, Marcin

    2016-03-31

    Targeting oncogenic transcription factor signal transducer and activator of transcription 3 (STAT3) in acute myeloid leukemia (AML) can reduce blast survival and tumor immune evasion. Decoy oligodeoxynucleotides (dODNs), which comprise STAT3-specific DNA sequences are competitive inhibition of STAT3 transcriptional activity. To deliver STAT3dODN specifically to myeloid cells, we linked STAT3dODN to the Toll-like receptor 9 (TLR9) ligand, cytosine guanine dinucleotide (CpG). The CpG-STAT3dODN conjugates are quickly internalized by human and mouse TLR9(+)immune cells (dendritic cells, B cells) and the majority of patients' derived AML blasts, including leukemia stem/progenitor cells. Following uptake, CpG-STAT3dODNs are released from endosomes, and bind and sequester cytoplasmic STAT3, thereby inhibiting downstream gene expression in target cells. STAT3 inhibition in patients' AML cells limits their immunosuppressive potential by reduced arginase expression, thereby partly restoring T-cell proliferation. Partly chemically modified CpG-STAT3dODNs have >60 hours serum half-life which allows for IV administration to leukemia-bearing mice (50% effective dose ∼ 2.5 mg/kg). Repeated administration of CpG-STAT3dODN resulted in regression of human MV4-11 AML in mice. The antitumor efficacy of this strategy is further enhanced in immunocompetent mice by combining direct leukemia-specific cytotoxicity with immunogenic effects of STAT3 blocking/TLR9 triggering. CpG-STAT3dODN effectively reducedCbfb/MYH11/MplAML burden in various organs and eliminated leukemia stem/progenitor cells, mainly through CD8/CD4 T-cell-mediated immune responses. In contrast, small-molecule Janus kinase 2/STAT3 inhibitor failed to reproduce therapeutic effects of cell-selective CpG-STAT3dODN strategy. These results demonstrate therapeutic potential of CpG-STAT3dODN inhibitors with broad implications for treatment of AML and potentially other hematologic malignancies.

  16. Induction of innate lymphoid cell-derived interleukin-22 by the transcription factor STAT3 mediates protection against intestinal infection.

    PubMed

    Guo, Xiaohuan; Qiu, Ju; Tu, Tony; Yang, Xuanming; Deng, Liufu; Anders, Robert A; Zhou, Liang; Fu, Yang-Xin

    2014-01-16

    Inhibitors of the transcription factor STAT3 target STAT3-dependent tumorigenesis but patients often develop diarrhea from unknown mechanisms. Here we showed that STAT3 deficiency increased morbidity and mortality after Citrobacter rodentium infection with decreased secretion of cytokines including IL-17 and IL-22 associated with the transcription factor RORγt. Administration of the cytokine IL-22 was sufficient to rescue STAT3-deficient mice from lethal infection. Although STAT3 was required for IL-22 production in both innate and adaptive arms, by using conditional gene-deficient mice, we observed that STAT3 expression in RORγt(+) innate lymphoid cells (ILC3s), but not T cells, was essential for the protection. However, STAT3 was required for RORγt expression in T helper cells, but not in ILC3s. Activated STAT3 could directly bind to the Il22 locus. Thus, cancer therapies that utilize STAT3 inhibitors increase the risk for pathogen-mediated diarrhea through direct suppression of IL-22 from gut ILCs.

  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. 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.

  19. Endogenous transmembrane protein UT2 inhibits pSTAT3 and suppresses hematological malignancy

    PubMed Central

    Wang, Ying-Hua; Kalaitzidis, Demetrios; Ramachandran, Janani; Sykes, David B.; Raje, Noopur; Scadden, David T.

    2016-01-01

    Regulation of STAT3 activation is critical for normal and malignant hematopoietic cell proliferation. Here, we have reported that the endogenous transmembrane protein upstream-of-mTORC2 (UT2) negatively regulates activation of STAT3. Specifically, we determined that UT2 interacts directly with GP130 and inhibits phosphorylation of STAT3 on tyrosine 705 (STAT3Y705). This reduces cytokine signaling including IL6 that is implicated in multiple myeloma and other hematopoietic malignancies. Modulation of UT2 resulted in inverse effects on animal survival in myeloma models. Samples from multiple myeloma patients also revealed a decreased copy number of UT2 and decreased expression of UT2 in genomic and transcriptomic analyses, respectively. Together, these studies identify a transmembrane protein that functions to negatively regulate cytokine signaling through GP130 and pSTAT3Y705 and is molecularly and mechanistically distinct from the suppressors of cytokine signaling (SOCS) family of genes. Moreover, this work provides evidence that perturbations of this activation-dampening molecule participate in hematologic malignancies and may serve as a key determinant of multiple myeloma pathophysiology. UT2 is a negative regulator shared across STAT3 and mTORC2 signaling cascades, functioning as a tumor suppressor in hematologic malignancies driven by those pathways. PMID:26927669

  20. Icaritin Reduces Oral Squamous Cell Carcinoma Progression via the Inhibition of STAT3 Signaling

    PubMed Central

    Yang, Jian-Guang; Lu, Rui; Ye, Xiao-Jing; Zhang, Jing; Tan, Ya-Qin; Zhou, Gang

    2017-01-01

    Icaritin, a traditional Chinese medicine, possesses antitumor activity. The current study aimed to investigate icaritin effect and potential mechanism on oral squamous cell carcinoma (OSCC) development. OSCC cells proliferation, apoptosis, and autophagy were analyzed after incubation with icaritin at different concentrations and incubation times. The expressions of proteins related to proliferation, apoptosis, and autophagy, as well as signal transducer and activator of transcription 3 (STAT3) signal network, were also evaluated by western blot. Furthermore, STAT3 was knocked down by siRNA transfection to determine STAT3 role in OSCC cell proliferation and apoptosis. An oral specific carcinogenesis mouse model was used to explore icaritin effect on OSCC in vivo. Icaritin significantly inhibited OSCC proliferation in vitro and reduced the expression of both the cell-cycle progression proteins cyclin A2 and cyclin D1. Besides, icaritin increased cleaved caspase 3 and cleaved poly-(ADP-ribose) polymerase expression leading to apoptosis, and it activated autophagy. Icaritin significantly inhibited the expression of phospho-STAT3 (p-STAT3) in a dose- and time-dependent manner. In the in vivo experiment, the number of malignant tumors in the icaritin-treated group was significantly lower than the control. Overall, icaritin suppressed proliferation, promoted apoptosis and autophagy, and inhibited STAT3 signaling in OSCC in vitro and in vivo. In conclusion, icaritin might be a potential therapeutic agent against OSCC development. PMID:28085115

  1. Targeting STAT3 in adoptively transferred T cells promotes their in vivo expansion and antitumor effects

    PubMed Central

    Kujawski, Maciej; Zhang, Chunyan; Herrmann, Andreas; Reckamp, Karen; Scuto, Anna; Jensen, Michael; Deng, Jiehui; Forman, Stephen; Figlin, Robert; Yu, Hua

    2010-01-01

    Adoptive cell therapy with engineered T cells to improve natural immune response and antitumor functions has shown promise for treating cancer. However, the requirement for extensive ex vivo manipulation of T cells and the immunosuppressive effects of the tumor microenvironment limit this therapeutic modality. In the present study, we investigated the possibility to circumvent these limitations by engineering Stat3-deficient CD8+ T cells or by targeting Stat3 in the tumor microenvironment. We show that ablating Stat3 in CD8+ T cells prior to their transfer allows their efficient tumor infiltration and robust proliferation, resulting in increased tumor antigen-specific T cell activity and tumor growth inhibition. For potential clinical translation, we combined adoptive T cell therapy with an FDA-approved tyrosine kinase inhibitor, sunitinib, in renal cell carcinoma and melanoma tumor models. Sunitinib inhibited Stat3 in dendritic cells and T cells, reduced conversion of transferred Foxp3− T cells to tumor-associated T regulatory cells while increasing transferred CD8+ T cell infiltration and activation at the tumor site, leading to inhibition of primary tumor growth. These data demonstrate that adoptively transferred T cells can be expanded and activated in vivo either by engineering Stat3 silenced T cells or by targeting Stat3 systemically with small-molecule inhibitors. PMID:21118964

  2. Stat3 expression and its correlation with proliferation and apoptosis/autophagy in gliomas.

    PubMed

    Caldera, Valentina; Mellai, Marta; Annovazzi, Laura; Valente, Guido; Tessitore, Luciana; Schiffer, Davide

    2008-01-01

    Signal transducer and activator of transcription-3 (Stat3) was studied along with several steps of the PI3/Akt pathway in a series of 64 gliomas that included both malignant and low-grade tumors, using quantitative immunohistochemistry, Western blotting, and molecular biology techniques. The goal of the study was to investigate whether activated Stat3 (phospho-Stat3) levels correlated with cell proliferation, apoptosis, and autophagy. Stat3 and activated Akt (phospho-Akt) expression increased with malignancy grade, but did not correlate with proliferation and survival within the category of glioblastomas. A correlation of Stat3 with Akt was found, indicating a regulation of the former by the PI3/Akt pathway, which, in turn, was in relation with EGFR amplification. Stat3 and Akt did not show any correlation with apoptosis, whereas they showed an inverse correlation with Beclin 1, a stimulator of autophagy, which was rarely positive in glioblastomas. Autophagy seems then to be inactivated in malignant gliomas.

  3. Sip-jeon-dea-bo-tang, a traditional herbal medicine, ameliorates cisplatin-induced anorexia via the activation of JAK1/STAT3-mediated leptin and IL-6 production in the fat tissue of mice.

    PubMed

    Woo, Sang-Mi; Choi, Youn Kyung; Kim, Ah-Jeong; Yun, Yee Jin; Shin, Yong Cheol; Cho, Sung-Gook; Ko, Seong Gyu

    2016-04-01

    Despite its therapeutic advantages, chemotherapy can also cause adverse effects, including anorexia and loss of appetite. Although numerous patients with cancer have been reported to suffer from anorexia during or following chemotherapy, treatment options for anorexia remain to be determined. In Asian countries, traditional medicines are widely used to treat problems with appetite; sip-jeon-dea-bo-tang (SJDBT) is one of those medicines used for the treatment of anorexia. The present study demonstrated that SJDBT ameliorated cisplatin-induced anorexia. In a mouse model of chemotherapy-induced anorexia, oral administration of SJDBT prevented the cisplatin-induced reduction of food intake, inhibiting weight loss. The results of multiplex assays showed that SJDBT only altered the levels of interleukin (IL)-6 and leptin in the serum and fat tissue. In addition, SJDBT maintained the serum leptin level and increased the serum IL-6 level, whereas cisplatin reduced the levels of both serum leptin and IL‑6. Furthermore, SJDBT was revealed to increase the levels of leptin and IL-6 in the fat tissue by activating the JAK1/STAT3 signaling pathway. In conclusion, the present results revealed that SJDBT ameliorated cisplatin-induced anorexia, suggesting its usefulness in the prevention of anorexia during chemotherapy.

  4. Pharmacological Targeting SHP-1-STAT3 Signaling Is a Promising Therapeutic Approach for the Treatment of Colorectal Cancer12

    PubMed Central

    Fan, Li-Ching; Teng, Hao-Wei; Shiau, Chung-Wai; Tai, Wei-Tien; Hung, Man-Hsin; Yang, Shung-Haur; Jiang, Jeng-Kai; Chen, Kuen-Feng

    2015-01-01

    STAT3 activation is associated with poor prognosis in human colorectal cancer (CRC). Our previous data demonstrated that regorafenib (Stivarga) is a pharmacological agonist of SH2 domain-containing phosphatase 1 (SHP-1) that enhances SHP-1 activity and induces apoptosis by targeting STAT3 signals in CRC. This study aimed to find a therapeutic drug that is more effective than regorafenib for CRC treatment. Here, we showed that SC-43 was more effective than regorafenib at inducing apoptosis in vitro and suppressing tumorigenesis in vivo. SC-43 significantly increased SHP-1 activity, downregulated p-STAT3Tyr705 level, and induced apoptosis in CRC cells. An SHP-1 inhibitor or knockdown of SHP-1 by siRNA both significantly rescued the SC-43–induced apoptosis and decreased p-STAT3Tyr705 level. Conversely, SHP-1 overexpression increased the effects of SC-43 on apoptosis and p-STAT3Tyr705 level. These data suggest that SC-43–induced apoptosis mediated through the loss of p-STAT3Tyr705 was dependent on SHP-1 function. Importantly, SC-43–enhanced SHP-1 activity was because of the docking potential of SC-43, which relieved the autoinhibited N-SH2 domain of SHP-1 and inhibited p-STAT3Tyr705 signals. Importantly, we observed that a significant negative correlation existed between SHP-1 and p-STAT3Tyr705expression in CRC patients (P = .038). Patients with strong SHP-1 and weak p-STAT3Tyr705 expression had significantly higher overall survival compared with patients with weak SHP-1 and strong p-STAT3Tyr705 expression (P = .029). In conclusion, SHP-1 is suitable to be a useful prognostic marker and a pharmacological target for CRC treatment. Targeting SHP-1-STAT3 signaling by SC-43 may serve as a promising pharmacotherapy for CRC. PMID:26476076

  5. Multiple regulation pathways and pivotal biological functions of STAT3 in cancer.

    PubMed

    Yuan, Jie; Zhang, Fei; Niu, Ruifang

    2015-12-03

    STAT3 is both a transcription activator and an oncogene that is tightly regulated under normal physiological conditions. However, abundant evidence indicates that STAT3 is persistently activated in several cancers, with a crucial position in tumor onset and progression. In addition to its traditional role in cancer cell proliferation, invasion, and migration, STAT3 also promotes cancer through altering gene expression via epigenetic modification, inducing epithelial-mesenchymal transition (EMT) phenotypes in cancer cells, regulating the tumor microenvironment, and promoting cancer stem cells (CSCs) self-renewal and differentiation. STAT3 is regulated not only by the canonical cytokines and growth factors, but also by the G-protein-coupled receptors, cadherin engagement, Toll-like receptors (TLRs), and microRNA (miRNA). Despite the presence of diverse regulators and pivotal biological functions in cancer, no effective therapeutic inventions are available for inhibiting STAT3 and acquiring potent antitumor effects in the clinic. An improved understanding of the complex roles of STAT3 in cancer is required to achieve optimal therapeutic effects.

  6. Multiple regulation pathways and pivotal biological functions of STAT3 in cancer

    PubMed Central

    Yuan, Jie; Zhang, Fei; Niu, Ruifang

    2015-01-01

    STAT3 is both a transcription activator and an oncogene that is tightly regulated under normal physiological conditions. However, abundant evidence indicates that STAT3 is persistently activated in several cancers, with a crucial position in tumor onset and progression. In addition to its traditional role in cancer cell proliferation, invasion, and migration, STAT3 also promotes cancer through altering gene expression via epigenetic modification, inducing epithelial–mesenchymal transition (EMT) phenotypes in cancer cells, regulating the tumor microenvironment, and promoting cancer stem cells (CSCs) self-renewal and differentiation. STAT3 is regulated not only by the canonical cytokines and growth factors, but also by the G-protein-coupled receptors, cadherin engagement, Toll-like receptors (TLRs), and microRNA (miRNA). Despite the presence of diverse regulators and pivotal biological functions in cancer, no effective therapeutic inventions are available for inhibiting STAT3 and acquiring potent antitumor effects in the clinic. An improved understanding of the complex roles of STAT3 in cancer is required to achieve optimal therapeutic effects. PMID:26631279

  7. FoxO1 negatively regulates leptin-induced POMC transcription through its direct interaction with STAT3.

    PubMed

    Ma, Wei; Fuentes, Gloria; Shi, Xiaohe; Verma, Chandra; Radda, George K; Han, Weiping

    2015-03-01

    FoxO1, which is up-regulated during early stages of diet-induced leptin resistance, directly interacts with STAT3 and prevents STAT3 from binding to specificity protein 1 (SP1)-pro-opiomelanocortin (POMC) promoter complex, and thereby inhibits STAT3-mediated regulation of POMC transcription. FoxO1 also binds directly to the POMC promoter and negatively regulates its transcription. The present study aims to understand the relative contribution of the two interactions in regulating POMC expression. We studied the structural requirement of FoxO1 for its interaction with STAT3 and POMC promoter, and tested the inhibitory action of FoxO1 mutants by using biochemical assays, molecular biology and computer modelling. FoxO1 mutant with deletion of residues Ala137-Leu160 failed to bind to STAT3 or inhibit STAT3-mediated POMC activation, although its binding to the POMC promoter was unaffected. Further analysis mapped Gly140-Leu160 to be critical for STAT3 binding. The identified region Gly140-Leu160 was conserved among mammalian FoxO1 proteins, and showed a high degree of sequence identity with FoxO3, but not FoxO4. Consistently, FoxO3 could interact with STAT3 and inhibit POMC promoter activity, whereas FoxO4 could not bind to STAT3 or affect POMC promoter activity. We further identified that five residues (Gln145, Arg147, Lys148, Arg153 and Arg154) in FoxO1 were necessary in FoxO1-STAT3 interaction, and mutation of these residues abolished its interaction with STAT3 and inhibition of POMC promoter activity. Finally, a FoxO1-STAT3 interaction interface model generated by computational docking simulations confirmed that the identified residues of FoxO1 were in close proximity to STAT3. These results show that FoxO1 inhibits STAT3-mediated leptin signalling through direct interaction with STAT3.

  8. Viability and stress protection of chronic lymphoid leukemia cells involves overactivation of mitochondrial phosphoSTAT3Ser727

    PubMed Central

    Capron, C; Jondeau, K; Casetti, L; Jalbert, V; Costa, C; Verhoyen, E; Massé, J M; Coppo, P; Béné, M C; Bourdoncle, P; Cramer-Bordé, E; Dusanter-Fourt, I

    2014-01-01

    Chronic lymphoid leukemia (CLL) is characterized by the accumulation of functionally defective CD5-positive B lymphocytes. The clinical course of CLL is highly variable, ranging from a long-lasting indolent disease to an unpredictable and rapidly progressing leukemia requiring treatment. It is thus important to identify novel factors that reflect disease progression or contribute to its assessment. Here, we report on a novel STAT3-mediated pathway that characterizes CLL B cells-extended viability and oxidative stress control. We observed that leukemic but not normal B cells from CLL patients exhibit constitutive activation of an atypical form of the STAT3 signaling factor, phosphorylated on serine 727 (Ser727) in the absence of detectable canonical tyrosine 705 (Tyr705)-dependent activation in vivo. The Ser727-phosphorylated STAT3 molecule (pSTAT3Ser727) is localized to the mitochondria and associates with complex I of the respiratory chain. This pSer727 modification is further controlled by glutathione-dependent antioxidant pathway(s) that mediate stromal protection of the leukemic B cells and regulate their viability. Importantly, pSTAT3Ser727, but neither Tyr705-phosphorylated STAT3 nor total STAT3, levels correlate with prolonged in vivo CLL B cells survival. Furthermore, STAT3 activity contributes to the resistance to apoptosis of CLL, but not normal B cells, in vitro. These data reveal that mitochondrial (Mt) pSTAT3Ser727 overactivity is part of the antioxidant defense pathway of CLL B cells that regulates their viability. Mt pSTAT3Ser727 appears to be a newly identified cell-protective signal involved in CLL cells survival. Targeting pSTAT3Ser727 could be a promising new therapeutic approach. PMID:25299776

  9. Distinct roles of STAT3 and STAT5 in the pathogenesis and targeted therapy of breast cancer

    PubMed Central

    Walker, Sarah R.; Xiang, Michael; Frank, David A.

    2013-01-01

    The transcription factors STAT3 and STAT5 play important roles in the regulation of mammary gland function during pregnancy, lactation, and involution. Given that STAT3 and STAT5 regulate genes involved in proliferation and survival, it is not surprising that inappropriate activation of STAT3 and STAT5 occurs commonly in breast cancer. Although these proteins are structurally similar, they have divergent and opposing effects on gene expression and cellular phenotype. Notably, when STAT5 and STAT3 are activated simultaneously, STAT5 has a dominant effect, and leads to decreased proliferation and increased sensitivity to cell death. Similarly, in breast cancer, activation of both STAT5 and STAT3 is associated with longer patient survival than activation of STAT3 alone. Pharmacological inhibitors of STAT3 and STAT5 are being developed for cancer therapy, though understanding the activation state and functional interaction of STAT3 and STAT5 in a patient's tumor may be critical for the optimal use of this strategy. PMID:23531638

  10. Sustained IL-6/STAT-3 Signaling in Cholangiocarcinoma Cells due to SOCS-3 Epigenetic Silencing

    PubMed Central

    Isomoto, Hajime; Mott, Justin L.; Kobayashi, Shogo; Werneburg, Nathan W.; Bronk, Steve F.; Haan, Serge; Gores, Gregory J.

    2008-01-01

    Background and aims IL-6 mediated STAT-3 phosphorylation (activation) is aberrantly sustained in cholangiocarcinoma cells resulting in enhanced Mcl-1 expression and resistance to apoptosis. Because SOCS-3 controls the IL-6/STAT-3 signaling pathway by a classic feedback loop, the aims of this study were to examine SOCS-3 regulation in human cholangiocarcinoma. Methods SOCS-3 expression was assessed in human cholangiocarcinoma tissue and the Mz-ChA-1 and CCLP1 human cholangiocarcinoma cell lines. Results An inverse correlation was observed between phospho-STAT-3 and SOCS-3 protein expression in cholangiocarcinoma. In those cancers failing to express SOCS-3, extensive methylation of the SOCS-3 promoter was demonstrated in tumor but not in paired non-tumor tissue. Likewise, methylation of the socs-3 promoter was also identified in two cholangiocarcinoma cell lines. Treatment with a demethylating agent, 5-aza-2′-deoxycytidine (DAC), restored IL-6 induction of SOCS-3, terminated the phospho-STAT-3 response, and reduced cellular levels of Mcl-1. Enforced expression of SOCS-3 also reduced IL-6 induction of phospho-STAT-3 and Mcl-1. Either DAC treatment or enforced SOCS-3 expression sensitized the cells to TRAIL-mediated apoptosis. Conclusion SOCS-3 epigenetic silencing is responsible for sustained IL-6/STAT-3 signaling and enhanced Mcl-1 expression in cholangiocarcinoma. PMID:17241887

  11. An essential role for the Stat3 in regulating IgG immune complex-induced pulmonary inflammation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Growing evidence suggests that transcription factor signal transducer and activator of transcription (Stat) 3 may play an important regulatory role during inflammation. However, the function of Stat3 in acute lung injury (ALI) is largely unknown. In the current study, by using an adenoviral vector e...

  12. miR520c blocks EMT progression of human breast cancer cells by repressing STAT3.

    PubMed

    Wang, Nian; Wei, Lan; Huang, Yunxiu; Wu, Yang; Su, Min; Pang, Xueli; Wang, Nian; Ji, Feihu; Zhong, Changli; Chen, Tingmei; Li, Bing

    2017-03-01

    Breast cancer is one of the most malignant diseases world-wide and it ranks the first among female cancers. Masses of intrinsic and extrinsic factors, especially the inflammatory factors can lead to breast cancer. Aberrant activation and accumulation of key molecules can lead to inflammation associated carcinogenesis. The signal transducers and activators of transcription 3 (STAT3) is one of them. Therefore, to evaluate the novel molecular mechanisms, STAT3 has become our focus for breast cancer targeted therapy. At present, many tumor suppressing microRNAs have been validated, and are the highlights in research on microRNAs. Thus, we predicted microRNAs which could putatively regulate STAT3 through databases and selected six to screen with Dual-luciferase assay. The result hinted that miR520c could bind with STAT3 3'UTR. We mutated the seed sequence of miR520c on STAT3 3'UTR, which illustrated a reverse effect compared with wild-type of STAT3 3'UTR. Subsequently, STAT3, p-STAT3 and miR520c were assessed in three different grades of breast cancer cells, with the degree of malignancy, we found an escalating trend of STAT3 and p-STAT3, on the contrary, a downward trend of miR520c. We observed STAT3 was deactivated by miR520c. Epithelial to mesenchymal transition (EMT) is a fatal transfer of cancer progression. To find out whether the downregulation of STAT3 can repress breast cancer motility and invasion ability, we detected EMT markers. The result implied a suppression effect on EMT. We overexpressed STAT3 to conduct rescue experiments, the result showed a recovery of STAT3 and EMT characteristics. Cell motility and invasion property were regained as well. In the study, we elucidated miR520c could inhibit breast cancer EMT by targeting STAT3. It can enrich the mechanism of breast cancer and may lay the foundation for breast cancer targeted treatment.

  13. Macrophages promote benzopyrene-induced tumor transformation of human bronchial epithelial cells by activation of NF-κB and STAT3 signaling in a bionic airway chip culture and in animal models.

    PubMed

    Li, Encheng; Xu, Zhiyun; Zhao, Hui; Sun, Zhao; Wang, Lei; Guo, Zhe; Zhao, Yang; Gao, Zhancheng; Wang, Qi

    2015-04-20

    We investigated the role of macrophages in promoting benzopyrene (BaP)-induced malignant transformation of human bronchial epithelial cells using a BaP-induced tumor transformation model with a bionic airway chip in vitro and in animal models. The bionic airway chip culture data showed that macrophages promoted BaP-induced malignant transformation of human bronchial epithelial cells, which was mediated by nuclear factor (NF)-κB and STAT3 pathways to induce cell proliferation, colony formation in chip culture, and tumorigenicity in nude mice. Blockage of interleukin (IL)-6 or tumor necrosis factor (TNF)-α signaling or inhibition of NF-κB, STAT3, or cyclinD1 expression abrogated the effect of macrophages on malignant transformation in the bionic airway chip culture. In vivo, macrophages promoted lung tumorigenesis in a carcinogen-induced animal model. Similarly, blockage of NF-κB, STAT3, or cyclinD1 using siRNA transfection decreased the carcinogen-induced tumorigenesis in rats. We demonstrated that macrophages are critical in promoting lung tumorigenesis and that the macrophage-initiated TNF-α/NF-κB/cyclinD1 and IL-6/STAT3/cyclinD1 pathways are primarily responsible for promoting lung tumorigenesis.

  14. Macrophages promote benzopyrene-induced tumor transformation of human bronchial epithelial cells by activation of NF-κB and STAT3 signaling in a bionic airway chip culture and in animal models

    PubMed Central

    Sun, Zhao; Wang, Lei; Guo, Zhe; Zhao, Yang; Gao, Zhancheng; Wang, Qi

    2015-01-01

    We investigated the role of macrophages in promoting benzopyrene (BaP)-induced malignant transformation of human bronchial epithelial cells using a BaP-induced tumor transformation model with a bionic airway chip in vitro and in animal models. The bionic airway chip culture data showed that macrophages promoted BaP-induced malignant transformation of human bronchial epithelial cells, which was mediated by nuclear factor (NF)-κB and STAT3 pathways to induce cell proliferation, colony formation in chip culture, and tumorigenicity in nude mice. Blockage of interleukin (IL)-6 or tumor necrosis factor (TNF)-α signaling or inhibition of NF-κB, STAT3, or cyclinD1 expression abrogated the effect of macrophages on malignant transformation in the bionic airway chip culture. In vivo, macrophages promoted lung tumorigenesis in a carcinogen-induced animal model. Similarly, blockage of NF-κB, STAT3, or cyclinD1 using siRNA transfection decreased the carcinogen-induced tumorigenesis in rats. We demonstrated that macrophages are critical in promoting lung tumorigenesis and that the macrophage-initiated TNF-α/NF-κB/cyclinD1 and IL-6/STAT3/cyclinD1 pathways are primarily responsible for promoting lung tumorigenesis. PMID:25823926

  15. A novel obatoclax derivative, SC-2001, induces apoptosis in hepatocellular carcinoma cells through SHP-1-dependent STAT3 inactivation.

    PubMed

    Chen, Kuen-Feng; Su, Jung-Chen; Liu, Chun-Yu; Huang, Jui-Wen; Chen, Kuei-Chiu; Chen, Wei-Lin; Tai, Wei-Tien; Shiau, Chung-Wai

    2012-08-01

    We investigated the effects of a novel compound, SC-2001, on hepatocellular carcinoma (HCC). SC-2001, which is structurally related to the Mcl-1 inhibitor obatoclax, showed better antitumor effects than obatoclax in HCC cell lines, including HepG2, PLC5 and Huh-7. Like obatoclax, SC-2001 inhibited the protein-protein interactions between Mcl-1 and Bak. However, SC-2001 downregulated the protein levels of Mcl-1 by reducing its transcription whereas obatoclax had no significant effect on Mcl-1 expression. As Mcl-1 is regulated by signal transducers and activators of transcription 3 (STAT3), we found that SC-2001 downregulated the phosphorylation of STAT3 (Tyr 705) and subsequently inhibited transcriptional activities of STAT3 in a dose-dependent manner. In addition to Mcl-1, STAT3-regulated proteins, including survivin and cyclin D1, were also repressed by SC-2001. Notably, SC-2001 reduced IL-6-induced STAT3 activation in HepG2 and PLC5 cells. Ectopic expression of STAT3 abolished the prominent apoptotic death in SC-2001-treated PLC5 cells, indicating that STAT3 is indispensable in mediating the effects of SC-2001. Importantly, SC-2001 enhanced the expression of SHP1, a negative regulator of STAT3. Inhibition of SHP-1 by either specific inhibitor or small interference RNA reduced the apoptotic effects of SC-2001, indicating that SHP-1 plays a key role in mediating SC2001-induced cell death. SC-2001 enhanced the activity of SHP-1 in all tested HCC cells including HepG2, PLC5 and Huh-7. Finally, SC-2001 reduced PLC5 tumor growth, downregulated p-STAT3 and upregulated SHP-1 expression and activity in vivo. In conclusion, our results suggest that SC-2001 induces apoptosis in HCC, and that this effect is mediated through SHP-1-dependent STAT3 inactivation.

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

    SciTech Connect

    Michaud-Levesque, Jonathan; Bousquet-Gagnon, Nathalie; Beliveau, Richard

    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.

  17. 6-Bromoindirubin-3'-oxime inhibits JAK/STAT3 signaling and induces apoptosis of human melanoma cells.

    PubMed

    Liu, Lucy; Nam, Sangkil; Tian, Yan; Yang, Fan; Wu, Jun; Wang, Yan; Scuto, Anna; Polychronopoulos, Panos; Magiatis, Prokopios; Skaltsounis, Leandros; Jove, Richard

    2011-06-01

    STAT3 is persistently activated and contributes to malignant progression in various cancers. Janus activated kinases (JAK) phosphorylate STAT3 in response to stimulation by cytokines or growth factors. The STAT3 signaling pathway has been validated as a promising target for development of anticancer therapeutics. Small-molecule inhibitors of JAK/STAT3 signaling represent potential molecular-targeted cancer therapeutic agents. In this study, we investigated the role of JAK/STAT3 signaling in 6-bromoindirubin-3'-oxime (6BIO)-mediated growth inhibition of human melanoma cells and assessed 6BIO as a potential anticancer drug candidate. We found that 6BIO is a pan-JAK inhibitor that induces apoptosis of human melanoma cells. 6BIO directly inhibited JAK-family kinase activity, both in vitro and in cancer cells. Apoptosis of human melanoma cells induced by 6BIO was associated with reduced phosphorylation of JAKs and STAT3 in both dose- and time-dependent manners. Consistent with inhibition of STAT3 signaling, expression of the antiapoptotic protein Mcl-1 was downregulated. In contrast to the decreased levels of phosphorylation of JAKs and STAT3, phosphorylation levels of the Akt and mitogen-activated protein kinase (MAPK) signaling proteins were not inhibited in cells treated with 6BIO. Importantly, 6BIO suppressed tumor growth in vivo with low toxicity in a mouse xenograft model of melanoma. Taken together, these results show that 6BIO is a novel pan-JAK inhibitor that can selectively inhibit STAT3 signaling and induces tumor cell apoptosis. Our findings support further development of 6BIO as a potential anticancer therapeutic agent that targets JAK/STAT3 signaling in tumor cells.

  18. Evaluation of STAT3 Signaling in ALDH+ and ALDH+/CD44+/CD24− Subpopulations of Breast Cancer Cells

    PubMed Central

    Lin, Li; Hutzen, Brian; Lee, Hsiu-Fang; Peng, Zhengang; Wang, Wenlong; Zhao, Chongqiang; Lin, Huey-Jen; Sun, Duxin; Li, Pui-Kai; Li, Chenglong; Korkaya, Hasan; Wicha, Max S.; Lin, Jiayuh

    2013-01-01

    Background STAT3 activation is frequently detected in breast cancer and this pathway has emerged as an attractive molecular target for cancer treatment. Recent experimental evidence suggests ALDH-positive (ALDH+), or cell surface molecule CD44-positive (CD44+) but CD24-negative (CD24−) breast cancer cells have cancer stem cell properties. However, the role of STAT3 signaling in ALDH+ and ALDH+/CD44+/CD24− subpopulations of breast cancer cells is unknown. Methods and Results We examined STAT3 activation in ALDH+ and ALDH+/CD44+/CD24− subpopulations of breast cancer cells by sorting with flow cytometer. We observed ALDH-positive (ALDH+) cells expressed higher levels of phosphorylated STAT3 compared to ALDH-negative (ALDH−) cells. There was a significant correlation between the nuclear staining of phosphorylated STAT3 and the expression of ALDH1 in breast cancer tissues. These results suggest that STAT3 is activated in ALDH+ subpopulations of breast cancer cells. STAT3 inhibitors Stattic and LLL12 inhibited STAT3 phosphorylation, reduced the ALDH+ subpopulation, inhibited breast cancer stem-like cell viability, and retarded tumorisphere-forming capacity in vitro. Similar inhibition of STAT3 phosphorylation, and breast cancer stem cell viability were observed using STAT3 ShRNA. In addition, LLL12 inhibited STAT3 downstream target gene expression and induced apoptosis in ALDH+ subpopulations of breast cancer cells. Furthermore, LLL12 inhibited STAT3 phosphorylation and tumor cell proliferation, induced apoptosis, and suppressed tumor growth in xenograft and mammary fat pad mouse models from ALDH+ breast cancer cells. Similar in vitro and tumor growth in vivo results were obtained when ALDH+ cells were further selected for the stem cell markers CD44+ and CD24−. Conclusion These studies demonstrate an important role for STAT3 signaling in ALDH+ and ALDH+/CD44+/CD24− subpopulations of breast cancer cells which may have cancer stem cell properties and suggest

  19. Targeting Mitochondrial STAT3 with the Novel Phospho-Valproic Acid (MDC-1112) Inhibits Pancreatic Cancer Growth in Mice

    PubMed Central

    Mackenzie, Gerardo G.; Huang, Liqun; Alston, Ninche; Ouyang, Nengtai; Vrankova, Kvetoslava; Mattheolabakis, George; Constantinides, Panayiotis P.; Rigas, Basil

    2013-01-01

    New agents are needed to treat pancreatic cancer, one of the most lethal human malignancies. We synthesized phospho-valproic acid, a novel valproic acid derivative, (P-V; MDC-1112) and evaluated its efficacy in the control of pancreatic cancer. P-V inhibited the growth of human pancreatic cancer xenografts in mice by 60%–97%, and 100% when combined with cimetidine. The dominant molecular target of P-V was STAT3. P-V inhibited the phosphorylation of JAK2 and Src, and the Hsp90-STAT3 association, suppressing the activating phosphorylation of STAT3, which in turn reduced the expression of STAT3-dependent proteins Bcl-xL, Mcl-1 and survivin. P-V also reduced STAT3 levels in the mitochondria by preventing its translocation from the cytosol, and enhanced the mitochondrial levels of reactive oxygen species, which triggered apoptosis. Inhibition of mitochondrial STAT3 by P-V was required for its anticancer effect; mitochondrial STAT3 overexpression rescued animals from the tumor growth inhibition by P-V. Our results indicate that P-V is a promising candidate drug against pancreatic cancer and establish mitochondrial STAT3 as its key molecular target. PMID:23650499

  20. Adenosine augments IL-10-induced STAT3 signaling in M2c macrophages.

    PubMed

    Koscsó, Balázs; Csóka, Balázs; Kókai, Endre; Németh, Zoltán H; Pacher, Pál; Virág, László; Leibovich, S Joseph; Haskó, György

    2013-12-01

    The alternatively activated macrophage phenotype induced by IL-10 is called M2c. Adenosine is an endogenous purine nucleoside that accumulates in the extracellular space in response to metabolic disturbances, hypoxia, inflammation, physical damage, or apoptosis. As adenosine is known to regulate classically activated M1 and IL4- and IL-13-activated M2a macrophages, the goal of the present study was to explore its effects on M2c macrophages. We found that adenosine augmented the IL-10-induced expression of TIMP-1 and arginase-1 by the mouse macrophage cell line RAW 264.7 and by mouse BMDMs. The effects of AR stimulation on IL-10-induced TIMP-1 or arginase-1 expression were lacking in A2BAR KO macrophages. The role of A2BAR on TIMP-1 production of RAW 264.7 cells was confirmed with specific agonist BAY606583 and antagonist PSB0788. AR stimulation augmented IL-10-induced STAT3 phosphorylation in macrophages, and pharmacological inhibition or silencing of STAT3 using siRNA reduced the stimulatory effect of AR stimulation on TIMP-1 production. In contrast to its stimulatory effect on IL-10-induced STAT3 activation, adenosine inhibited IL-6-induced STAT3 phosphorylation and SAA3 expression. In conclusion, adenosine enhances IL-10-induced STAT3 signaling and M2c macrophage activation.

  1. The Stat3/GR interaction code: predictive value of direct/indirect DNA recruitment for transcription outcome.

    PubMed

    Langlais, David; Couture, Catherine; Balsalobre, Aurélio; Drouin, Jacques

    2012-07-13

    Transcription factor recruitment to genomic sites of action is primarily due to direct protein:DNA interactions. The subsequent recruitment of coregulatory complexes leads to either transcriptional activation or repression. In contrast to this canonical scheme, some transcription factors, such as the glucocorticoid receptor (GR), behave as transcriptional repressors when recruited to target genes through protein tethering. We have investigated the genome-wide prevalence of tethering between GR and Stat3 and found nonreciprocal interactions, namely that GR tethering to DNA-bound Stat3 results in transcriptional repression, whereas Stat3 tethering to GR results in synergism. Further, other schemes of GR and Stat3 corecruitment to regulatory modules result in transcriptional synergism, including neighboring and composite binding sites. The results indicate extensive transcriptional interactions between Stat3 and GR; further, they provide a genome-wide assessment of transcriptional regulation by tethering and a molecular basis for integration of signals mediated by GR and Stats in health and disease.

  2. Keratinocyte-specific stat3 heterozygosity impairs development of skin tumors in human papillomavirus 8 transgenic mice.

    PubMed

    De Andrea, Marco; Rittà, Massimo; Landini, Manuela M; Borgogna, Cinzia; Mondini, Michele; Kern, Florian; Ehrenreiter, Karin; Baccarini, Manuela; Marcuzzi, Gian Paolo; Smola, Sigrun; Pfister, Herbert; Landolfo, Santo; Gariglio, Marisa

    2010-10-15

    Human papillomaviruses (HPV) of the genus β are thought to play a role in human skin cancers, but this has been difficult to establish using epidemiologic approaches. To gain insight into the transforming activities of β-HPV, transgenic mouse models have been generated that develop skin tumors. Recent evidence suggests a central role of signal transducer and activator of transcription 3 (Stat3) as a transcriptional node for cancer cell-autonomous initiation of a tumor-promoting gene signature associated with cell proliferation, cell survival, and angiogenesis. Moreover, high levels of phospho-Stat3 have been detected in tumors arising in HPV8-CER transgenic mice. In this study, we investigate the in vivo role of Stat3 in HPV8-induced skin carcinogenesis by combining our established experimental model of HPV8-induced skin cancer with epidermis-restricted Stat3 ablation. Stat3 heterozygous epidermis was less prone to tumorigenesis than wild-type epidermis. Three of the 23 (13%) Stat3(+/-):HPV8 animals developed tumors within 12 weeks of life, whereas 54.3% of Stat3(+/+):HPV8 mice already exhibited tumors in the same observation period (median age for tumor appearance, 10 weeks). The few tumors that arose in the Stat3(+/-):HPV8 mice were benign and never progressed to a more malignant phenotype. Collectively, these results offer direct evidence of a critical role for Stat3 in HPV8-driven epithelial carcinogenesis. Our findings imply that targeting Stat3 activity in keratinocytes may be a viable strategy to prevent and treat HPV-induced skin cancer.

  3. Mesoderm-specific Stat3 deletion affects expression of Sox9 yielding Sox9-dependent phenotypes

    PubMed Central

    Hall, Michael D.; Murray, Caroline A.; Perantoni, Alan O.

    2017-01-01

    To date, mutations within the coding region and translocations around the SOX9 gene both constitute the majority of genetic lesions underpinning human campomelic dysplasia (CD). While pathological coding-region mutations typically result in a non-functional SOX9 protein, little is known about what mechanism(s) controls normal SOX9 expression, and subsequently, which signaling pathways may be interrupted by alterations occurring around the SOX9 gene. Here, we report the identification of Stat3 as a key modulator of Sox9 expression in nascent cartilage and developing chondrocytes. Stat3 expression is predominant in tissues of mesodermal origin, and its conditional ablation using mesoderm-specific TCre, in vivo, causes dwarfism and skeletal defects characteristic of CD. Specifically, Stat3 loss results in the expansion of growth plate hypertrophic chondrocytes and deregulation of normal endochondral ossification in all bones examined. Conditional deletion of Stat3 with a Sox9Cre driver produces palate and tracheal irregularities similar to those described in Sox9+/- mice. Furthermore, mesodermal deletion of Stat3 causes global embryonic down regulation of Sox9 expression and function in vivo. Mechanistic experiments ex vivo suggest Stat3 can directly activate the expression of Sox9 by binding to its proximal promoter following activation. These findings illuminate a novel role for Stat3 in chondrocytes during skeletal development through modulation of a critical factor, Sox9. Importantly, they further provide the first evidence for the modulation of a gene product other than Sox9 itself which is capable of modeling pathological aspects of CD and underscore a potentially valuable therapeutic target for patients with the disorder. PMID:28166224

  4. Autophagy Promotes the Repair of Radiation-Induced DNA Damage in Bone Marrow Hematopoietic Cells via Enhanced STAT3 Signaling.

    PubMed

    Xu, Fei; Li, Xin; Yan, Lili; Yuan, Na; Fang, Yixuan; Cao, Yan; Xu, Li; Zhang, Xiaoying; Xu, Lan; Ge, Chaorong; An, Ni; Jiang, Gaoyue; Xie, Jialing; Zhang, Han; Jiang, Jiayi; Li, Xiaotian; Yao, Lei; Zhang, Suping; Zhou, Daohong; Wang, Jianrong

    2017-03-01

    Autophagy protects hematopoietic cells from radiation damage in part by promoting DNA damage repair. However, the molecular mechanisms by which autophagy regulates DNA damage repair remain largely elusive. Here, we report that this radioprotective effect of autophagy depends on STAT3 signaling in murine bone marrow mononuclear cells (BM-MNCs). Specifically, we found that STAT3 activation and nuclear translocation in BM-MNCs were increased by activation of autophagy with an mTOR inhibitor and decreased by knockout of the autophagy gene Atg7. The autophagic regulation of STAT3 activation is likely mediated by induction of KAP1 degradation, because we showed that KAP1 directly interacted with STAT3 in the cytoplasm and knockdown of KAP1 increased the phosphorylation and nuclear translocation of STAT3. Subsequently, activated STAT3 transcriptionally upregulated the expression of BRCA1, which increased the ability of BM-MNCs to repair radiation-induced DNA damage. This novel finding that activation of autophagy can promote DNA damage repair in BM-MNCs via the ATG-KAP1-STAT3-BRCA1 pathway suggests that autophagy plays an important role in maintaining genomic integrity of BM-MNCs and its activation may confer protection of BM-MNCs against radiation-induced genotoxic stress.

  5. Nicotine protects against DSS colitis through regulating microRNA-124 and STAT3.

    PubMed

    Qin, Zhen; Wan, Jing-Jing; Sun, Yang; Wu, Tingyu; Wang, Peng-Yuan; Du, Peng; Su, Ding-Feng; Yang, Yili; Liu, Xia

    2017-02-01

    Although it is generally believed that nicotine accounts for the beneficial effect of smoking on ulcerative colitis, the underlying mechanisms remain not well understood. Our previous finding that nicotine inhibits inflammatory responses through inducing miR-124 prompted us to ask whether the miRNA is involved in the protective action of nicotine against UC. Our present study found that miR-124 expression is upregulated in colon tissues from UC patients and DSS colitis mice. Nicotine treatment further augmented miR-124 expression in lymphocytes isolated from human ulcerative colonic mucosa and ulcerative colon tissues from DSS mice, both in infiltrated lymphocytes and epithelial cells. Moreover, knockdown of miR-124 significantly diminished the beneficial effect of nicotine on murine colitis and IL-6-treated Caco-2 colon epithelial cells. Further analysis indicated that nicotine inhibited STAT3 activation in vivo and in IL-6 treated Caco-2 cells and Jurkat human T lymphocytes, in which miR-124 knockdown led to increased activation of STAT3. Blocking STAT3 activity alone is beneficial for DSS colitis and also abolished nicotine's protective effect in this model. These data indicate that nicotine exerts its protective action in UC through inducing miR-124 and inhibiting STAT3, and suggest that the miR-124/STAT3 system is a potential target for the therapeutic intervention of UC.

  6. 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. PMID:26106584

  7. 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

  8. Silencing of the transcription factor STAT3 sensitizes lung cancer cells to DNA damaging drugs, but not to TNFα- and NK cytotoxicity

    SciTech Connect

    Kulesza, Dorota W.; Carré, Thibault; Chouaib, Salem; Kaminska, Bozena

    2013-02-15

    Transcription factor STAT3 (Signal Transducers and Activators of Transcription 3) is persistently active in human tumors and may contribute to tumor progression. Inhibition of STAT3 expression/activity could be a good strategy to modulate tumor cell survival and responses to cancer chemotherapeutics or immune cytotoxicity. We silenced STAT3 expression in human A549 lung cancer cells to elucidate its role in cell survival and resistance to chemotherapeutics, TNFα and natural killer (NK)-mediated cytotoxicity. We demonstrate that STAT3 is not essential for basal survival and proliferation of A549 cancer cells. Stable silencing of STAT3 expression sensitized A549 cells to DNA damaging chemotherapeutics doxorubicin and cisplatin in a p53-independent manner. Sensitization to DNA damage-inducing chemotherapeutics could be due to down-regulation of the Bcl-xL expression in STAT3 depleted cells. In contrast, knockdown of STAT3 in cancer cells did not modulate responses to TNFα and NK-mediated cytotoxicity. We found that STAT3 depletion increased the NFκB activity likely providing the compensatory, pro-survival signal. The treatment with TNFα, but not doxorubicin, enhanced this effect. We conclude that STAT3 is not crucial for the control of basal cell proliferation and survival of lung carcinoma cells but modulates susceptibility to DNA damaging chemotherapeutics by regulation of intrinsic pro-survival pathways. - Highlights: ► STAT3 silencing is negligent for basal lung cancer cell viability and proliferation. ► STAT3 depletion sensitizes lung cancer cells to DNA damaging chemotherapeutics. ► STAT3 depletion has no effect on susceptibility to extrinsic apoptosis inducers. ► Increased pro-survival NFκB activity may compensate for STAT3 depletion.

  9. Inhibition of the JAK-STAT3 pathway by andrographolide enhances chemosensitivity of cancer cells to doxorubicin.

    PubMed

    Zhou, Jing; Ong, Choon-Nam; Hur, Gang-Min; Shen, Han-Ming

    2010-05-01

    Andrographolide (Andro), a diterpenoid lactone isolated from a traditional herbal medicine Andrographis paniculata, is known to possess potent anti-inflammatory and anticancer properties. In this study, we sought to examine the effect of Andro on signal transducer and activator of transcription 3 (STAT3) pathway and evaluate whether suppression of STAT3 activity by Andro could sensitize cancer cells to a chemotherapeutic drug doxorubicin. First, we demonstrated that Andro is able to significantly suppress both constitutively activated and IL-6-induced STAT3 phosphorylation and subsequent nuclear translocation in cancer cells. Such inhibition is found to be achieved through suppression of Janus-activated kinase (JAK)1/2 and interaction between STAT3 and gp130. For understanding the biological significance of the inhibitory effect of Andro on STAT3, we next investigated the effect of Andro on doxorubicin-induced apoptosis in human cancer cells. In our study the constitutive activation level of STAT3 was found to be correlated to the resistance of cancer cells to doxorubicin-induced apoptosis. Both the short-term MTT assay and the long-term colony formation assay showed that Andro dramatically promoted doxorubicin-induced cell death in cancer cells, indicating that Andro enhances the sensitivity of cancer cells to doxorubicin mainly via STAT3 suppression. These observations thus reveal a novel anticancer function of Andro and suggest a potential therapeutic strategy of using Andro in combination with chemotherapeutic agents for treatment of cancer.

  10. Shp2 Inhibits Proliferation of Esophageal Squamous Cell Cancer via Dephosphorylation of Stat3.

    PubMed

    Qi, Chen; Han, Tao; Tang, Hua; Huang, Kenan; Min, Jie; Li, Jing; Ding, Xinyu; Xu, Zhifei

    2017-01-12

    Shp2 (Src-homology 2 domain-containing phosphatase 2) was originally reported as an oncogene in kinds of solid tumors and hematologic malignancies. However, recent studies indicated that Shp2 may act as tumor suppressors in several tumor types. We investigated the function of Shp2 in esophageal squamous cell cancer (ESCC). The expression level of Shp2 was analyzed in tumor tissues in comparison with adjacent normal tissues of ESCC patients by immunohistochemistry and Western blot. Shp2 was knocked down by Short hairpin RNA to evaluate its function in ESCC cell lines. The relationship between Shp2 and p-Stat3 (signal transducer and activator of transcription 3) in human ESCC tissues was statistically examined. A significant low expression of Shp2 was found in ESCC tissues. Low expression of Shp2 was related to poorer overall survival in patients from The Cancer Genome Atlas (TCGA) dataset. Knockdown of Shp2 increased the growth of ESCC cell lines both in vivo and vitro. Activation of Stat3 (p-Stat3) was induced by Shp2 depletion. Expression of p-Stat3 was negatively correlated with Shp2 expression in ESCC tissues. Furthermore, knockdown of Shp2 attenuated cisplatin-sensitivity of ESCC cells. Shp2 might suppress the proliferation of ESCC by dephosphorylation of p-Stat3 and represents a novel research field for targeted therapy.

  11. Shp2 Inhibits Proliferation of Esophageal Squamous Cell Cancer via Dephosphorylation of Stat3

    PubMed Central

    Qi, Chen; Han, Tao; Tang, Hua; Huang, Kenan; Min, Jie; Li, Jing; Ding, Xinyu; Xu, Zhifei

    2017-01-01

    Shp2 (Src-homology 2 domain-containing phosphatase 2) was originally reported as an oncogene in kinds of solid tumors and hematologic malignancies. However, recent studies indicated that Shp2 may act as tumor suppressors in several tumor types. We investigated the function of Shp2 in esophageal squamous cell cancer (ESCC). The expression level of Shp2 was analyzed in tumor tissues in comparison with adjacent normal tissues of ESCC patients by immunohistochemistry and Western blot. Shp2 was knocked down by Short hairpin RNA to evaluate its function in ESCC cell lines. The relationship between Shp2 and p-Stat3 (signal transducer and activator of transcription 3) in human ESCC tissues was statistically examined. A significant low expression of Shp2 was found in ESCC tissues. Low expression of Shp2 was related to poorer overall survival in patients from The Cancer Genome Atlas (TCGA) dataset. Knockdown of Shp2 increased the growth of ESCC cell lines both in vivo and vitro. Activation of Stat3 (p-Stat3) was induced by Shp2 depletion. Expression of p-Stat3 was negatively correlated with Shp2 expression in ESCC tissues. Furthermore, knockdown of Shp2 attenuated cisplatin-sensitivity of ESCC cells. Shp2 might suppress the proliferation of ESCC by dephosphorylation of p-Stat3 and represents a novel research field for targeted therapy. PMID:28085101

  12. Saw Palmetto Extract Inhibits Metastasis and Antiangiogenesis through STAT3 Signal Pathway in Glioma Cell.

    PubMed

    Ding, Hong; Shen, Jinglian; Yang, Yang; Che, Yuqin

    2015-01-01

    Signal transducer and activator of transcription factor 3 (STAT3) plays an important role in the proliferation and angiogenesis in human glioma. Previous research indicated that saw palmetto extract markedly inhibited the proliferation of human glioma cells through STAT3 signal pathway. But its effect on tumor metastasis and antiangiogenesis is not clear. This study is to further clear the impact of saw palmetto extract on glioma cell metastasis, antiangiogenesis, and its mechanism. TUNEL assay indicated that the apoptotic cells in the saw palmetto treated group are higher than that in the control group (p < 0.05). The apoptosis related protein is detected and the results revealed that saw palmetto extract inhibits the proliferation of human glioma. Meanwhile pSTAT3 is lower in the experimental group and CD34 is also inhibited in the saw palmetto treated group. This means that saw palmetto extract could inhibit the angiogenesis in glioma. We found that saw palmetto extract was an important phytotherapeutic drug against the human glioma through STAT3 signal pathway. Saw palmetto extract may be useful as an adjunctive therapeutic agent for treatment of individuals with glioma and other types of cancer in which STAT3 signaling is activated.

  13. Saw Palmetto Extract Inhibits Metastasis and Antiangiogenesis through STAT3 Signal Pathway in Glioma Cell

    PubMed Central

    Ding, Hong; Shen, Jinglian; Yang, Yang; Che, Yuqin

    2015-01-01

    Signal transducer and activator of transcription factor 3 (STAT3) plays an important role in the proliferation and angiogenesis in human glioma. Previous research indicated that saw palmetto extract markedly inhibited the proliferation of human glioma cells through STAT3 signal pathway. But its effect on tumor metastasis and antiangiogenesis is not clear. This study is to further clear the impact of saw palmetto extract on glioma cell metastasis, antiangiogenesis, and its mechanism. TUNEL assay indicated that the apoptotic cells in the saw palmetto treated group are higher than that in the control group (p < 0.05). The apoptosis related protein is detected and the results revealed that saw palmetto extract inhibits the proliferation of human glioma. Meanwhile pSTAT3 is lower in the experimental group and CD34 is also inhibited in the saw palmetto treated group. This means that saw palmetto extract could inhibit the angiogenesis in glioma. We found that saw palmetto extract was an important phytotherapeutic drug against the human glioma through STAT3 signal pathway. Saw palmetto extract may be useful as an adjunctive therapeutic agent for treatment of individuals with glioma and other types of cancer in which STAT3 signaling is activated. PMID:26788112

  14. STAT1 and STAT3 in tumorigenesis: A matter of balance.

    PubMed

    Avalle, Lidia; Pensa, Sara; Regis, Gabriella; Novelli, Francesco; Poli, Valeria

    2012-04-01

    The transcription factors STAT1 and STAT3 appear to play opposite roles in tumorigenesis. While STAT3 promotes cell survival/proliferation, motility and immune tolerance and is considered as an oncogene, STAT1 mostly triggers anti-proliferative and pro-apoptotic responses while enhancing anti-tumor immunity. Despite being activated downstream of common cytokine and growth factor receptors, their activation is reciprocally regulated and perturbation in their balanced expression or phosphorylation levels may re-direct cytokine/growth factor signals from proliferative to apoptotic, or from inflammatory to anti-inflammatory. Here we review the functional canonical and non-canonical effects of STAT1 and STAT3 activation in tumorigenesis and their potential cross-regulation mechanisms.

  15. Inhibition of the STAT3 signaling pathway contributes to apigenin-mediated anti-metastatic effect in melanoma.

    PubMed

    Cao, Hui-Hui; Chu, Jian-Hong; Kwan, Hiu-Yee; Su, Tao; Yu, Hua; Cheng, Chi-Yan; Fu, Xiu-Qiong; Guo, Hui; Li, Ting; Tse, Anfernee Kai-Wing; Chou, Gui-Xin; Mo, Huan-Biao; Yu, Zhi-Ling

    2016-02-25

    Signal transducer and activator of transcription 3 (STAT3) signaling is constantly activated in human melanoma, and promotes melanoma metastasis. The dietary flavonoid apigenin is a bioactive compound that possesses low toxicity and exerts anti-metastatic activity in melanoma. However, the anti-metastasis mechanism of apigenin has not been fully elucidated. In the present study, we showed that apigenin suppressed murine melanoma B16F10 cell lung metastasis in mice, and inhibited cell migration and invasion in human and murine melanoma cells. Further study indicated that apigenin effectively suppressed STAT3 phosphorylation, decreased STAT3 nuclear localization and inhibited STAT3 transcriptional activity. Apigenin also down-regulated STAT3 target genes MMP-2, MMP-9, VEGF and Twist1, which are involved in cell migration and invasion. More importantly, overexpression of STAT3 or Twist1 partially reversed apigenin-impaired cell migration and invasion. Our data not only reveal a novel anti-metastasis mechanism of apigenin but also support the notion that STAT3 is an attractive and promising target for melanoma treatment.

  16. Inhibition of the STAT3 signaling pathway contributes to apigenin-mediated anti-metastatic effect in melanoma

    PubMed Central

    Cao, Hui-Hui; Chu, Jian-Hong; Kwan, Hiu-Yee; Su, Tao; Yu, Hua; Cheng, Chi-Yan; Fu, Xiu-Qiong; Guo, Hui; Li, Ting; Tse, Anfernee Kai-Wing; Chou, Gui-Xin; Mo, Huan-Biao; Yu, Zhi-Ling

    2016-01-01

    Signal transducer and activator of transcription 3 (STAT3) signaling is constantly activated in human melanoma, and promotes melanoma metastasis. The dietary flavonoid apigenin is a bioactive compound that possesses low toxicity and exerts anti-metastatic activity in melanoma. However, the anti-metastasis mechanism of apigenin has not been fully elucidated. In the present study, we showed that apigenin suppressed murine melanoma B16F10 cell lung metastasis in mice, and inhibited cell migration and invasion in human and murine melanoma cells. Further study indicated that apigenin effectively suppressed STAT3 phosphorylation, decreased STAT3 nuclear localization and inhibited STAT3 transcriptional activity. Apigenin also down-regulated STAT3 target genes MMP-2, MMP-9, VEGF and Twist1, which are involved in cell migration and invasion. More importantly, overexpression of STAT3 or Twist1 partially reversed apigenin-impaired cell migration and invasion. Our data not only reveal a novel anti-metastasis mechanism of apigenin but also support the notion that STAT3 is an attractive and promising target for melanoma treatment. PMID:26911838

  17. 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/π 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

  18. Roles of STAT3 and ZEB1 proteins in E-cadherin down-regulation and human colorectal cancer epithelial-mesenchymal transition.

    PubMed

    Xiong, Hua; Hong, Jie; Du, Wan; Lin, Yan-wei; Ren, Lin-lin; Wang, Ying-chao; Su, Wen-yu; Wang, Ji-lin; Cui, Yun; Wang, Zhen-hua; Fang, Jing-Yuan

    2012-02-17

    The progression of colorectal carcinoma (CRC) to invasive and metastatic disease may involve localized occurrences of epithelial-mesenchymal transition (EMT). However, mechanisms of the EMT process in CRC progression are not fully understood. We previously showed that knockdown of signal transducer and activator of transcription 3 (STAT3) up-regulated E-cadherin (a key component in EMT progression) in CRC. In this study, we examined the roles of STAT3 in CRC EMT and ZEB1, an EMT inducer, in STAT3-induced down-regulation of E-cadherin. Knockdown of STAT3 significantly increased E-cadherin and decreased N-cadherin and vimentin expressions in highly invasive LoVo CRC cells. Meanwhile, overexpression of STAT3 significantly reduced E-cadherin and enhanced N-cadherin and vimentin expressions in weakly invasive SW1116 CRC cells. Activation of STAT3 significantly increased CRC cell invasiveness and resistance to apoptosis. Knockdown of STAT3 dramatically enhanced chemosensitivity of CRC cells to fluorouracil. STAT3 regulated ZEB1 expression in CRC cells, and the STAT3-induced decrease in E-cadherin and cell invasion depended on activation of ZEB1 in CRC cells. Additionally, pSTAT3(Tyr-705) and ZEB1 expressions were significantly correlated with TNM (tumor, lymph node, and metastasis stages) (p < 0.01). In conclusion, STAT3 may directly mediate EMT progression and regulate ZEB1 expression in CRC. ZEB1 may participate in STAT3-induced cell invasion and E-cadherin down-regulation in CRC cells. The expressions of pSTAT3(Tyr-705) and ZEB1 may be positively associated with CRC metastasis. Our data may provide potential targets to prevent and/or treat CRC invasion and metastasis.

  19. A novel small molecule STAT3 inhibitor, LY5, inhibits cell viability, colony formation, and migration of colon and liver cancer cells

    PubMed Central

    Yu, Wenying; Jou, David; Wang, Yina; Ma, Haiyan; Xiao, Hui; Qin, Hua; Zhang, Cuntai; Lü, Jiagao; Li, Sheng; Li, Chenglong; Lin, Jiayuh; Lin, Li

    2016-01-01

    Signal Transducer and Activator of Transcription 3 (STAT3) is persistently activated in human liver and colon cancer cells and is required for cancer cell viability, survival and migration. Therefore, inhibition of STAT3 signaling may be a viable therapeutic approach for these two cancers. We recently designed a non-peptide small molecule STAT3 inhibitor, LY5, using in silico site-directed Fragment-based drug design (FBDD). The inhibitory effect on STAT3 phosphorylation, cell viability, migration and colony forming ability by LY5 were examined in human liver and colon cancer cells. We demonstrated that LY5 inhibited constitutive Interleukin-6 (IL-6)-induced STAT3 phosphorylation, STAT3 nuclear translocation, decreased STAT3 downstream targeted gene expression and induced apoptosis in liver and colon cancer cells. LY5 had little effect on STAT1 phosphorylation mediated by IFN-γ. Inhibition of persistent STAT3 phosphorylation by LY5 also inhibited colony formation, cell migration, and decreased the viability of liver cancer and colon cancer cells. Furthermore, LY5 inhibited STAT3 phosphorylation and suppressed colon tumor growth in a mouse model in vivo. Our results suggest that LY5 is a potent STAT3 inhibitor and may be a potential drug candidate for liver and colon cancer therapy. PMID:26883202

  20. Thymoquinone inhibits proliferation in gastric cancer via the STAT3 pathway in vivo and in vitro

    PubMed Central

    Zhu, Wen-Qian; Wang, Jun; Guo, Xu-Feng; Liu, Zhou; Dong, Wei-Guo

    2016-01-01

    AIM: To elucidate the mechanism of thymoquinone (TQ)-induced apoptosis in human gastric cancer cells in vitro and in vivo. METHODS: HGC27, BGC823, and SGC7901 cells were cultured in vitro and treated with TQ (0, 10, 25, 50, 75, 100, 125 μmol/L) for 12 h, 24 h, and 36 h, and then the proliferation inhibitory rates were detected by methylthiazole tetrazolium assay. Apoptosis was observed after Hoechst staining. The protein expressions of signal transducer and activator of transcription (STAT)3, p-STAT3, STAT5, p-STAT5, phospho-janus-activated kinase 2 (JAK2), JAK2, p-Src, Src, glyceraldehyde-3-phosphate dehydrogenase, lamin-A, survivin, Cyclin D, Bcl-2, Bax, peroxisome proliferator activated receptor, and caspase-3,7,9 were detected by western blot. Cell cycle and apoptosis were determined with flow cytometry. TQ induced dose-dependent apoptotic cell death in HGC27 cells was measured by Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) analysis and Hoechst 33258. RESULTS: TQ inhibited the phosphorylation of STAT3 but not STAT5. TQ-induced downregulation of STAT3 activation was associated with a reduction in JAK2 and c-Src activity. TQ also downregulated the expression of STAT3-regulated genes, such as Bcl-2, cyclin D, survivin, and vascular endothelial growth factor, and activated caspase-3,7,9. Consistent with the in vitro results, TQ was significantly effective as an antitumor agent in a xenograft tumor mouse model. CONCLUSION: This study provides strong evidence that downregulation of the STAT3 signaling pathway mediates TQ-induced apoptosis in gastric cancer. PMID:27122665

  1. Novel Role of Mitochondrial Manganese Superoxide Dismutase in STAT3 Dependent Pluripotency of Mouse Embryonic Stem Cells

    PubMed Central

    Sheshadri, Preethi; Ashwini, Ashwathnarayan; Jahnavi, Sowmya; Bhonde, Ramesh; Prasanna, Jyothi; Kumar, Anujith

    2015-01-01

    Leukemia Inhibitory Factor (LIF)/Signal transducer and activator of transcription 3 (STAT3) signaling pathway maintains the stemness and pluripotency of mouse embryonic stem cells (mESCs). Detailed knowledge on key intermediates in this pathway as well as any parallel pathways is largely missing. We initiated our study by investigating the effect of small molecule Curcumin on various signalling pathways essential for self-renewal. Curcumin sustained the LIF independent self-renewal of mESCs and induced pluripotent stem cells (miPSCs) in a STAT3 activity dependent manner. Gene expression analysis showed LIF/STAT3 and redox signaling components to be majorly modulated. Amongst ROS genes, expression of Manganese Superoxide Dismutase (MnSOD) specifically relied on STAT3 signaling as evidenced by STAT3 inhibition and reporter assay. The silencing of MnSOD, but not Cu-ZnSOD expression, resulted in the loss of mESC pluripotency in presence of LIF, and the overexpression of MnSOD is sufficient for maintaining the expression of pluripotent genes in the absence of STAT3 signaling. Finally, we demonstrate MnSOD to stabilize the turnover of pluripotent proteins at the post-translational level by modulating proteasomal activity. In conclusion, our findings unravel a novel role of STAT3 mediated MnSOD in the self-renewal of mESCs. PMID:25822711

  2. Sinomenine inhibits A549 human lung cancer cell invasion by mediating the STAT3 signaling pathway

    PubMed Central

    Jiang, Shulong; Gao, Yebo; Hou, Wei; Liu, Rui; Qi, Xin; Xu, Xia; Li, Jie; Bao, Yanju; Zheng, Honggang; Hua, Baojin

    2016-01-01

    Increasing evidence suggests that the failure of lung cancer treatment may occur as a result of tumor invasion and metastasis. Signal transducer and activator of transcription 3 (STAT3), an epithelial-mesenchymal transition-inducing transcription factor, is a key signaling molecule involved in the proliferation, apoptosis, invasion and metastasis of tumor cells. Sinomenine is an alkaloid compound with an antineoplastic potential against a variety of cancer cells. The aim of the present study was to assess the antitumor mechanisms of sinomenine in the A549 human lung cancer cell line. The results demonstrated that sinomenine manifested dose-dependent cytotoxicity and induced apoptosis in A549 cells. The protein expression of Janus kinase 2, STAT3, phosphorylated-STAT3, Snail, N-cadherin and vimentin decreased in sinomenine-treated cells, while E-cadherin protein expression increased. The regulation of STAT3, N-cadherin and E-cadherin by sinomenine was further confirmed by reverse transcription-quantitative polymerase chain reaction and immunofluorescent staining. It was demonstrated that sinomenine exerts inhibitory effects on A549 human lung cancer cell invasion, possibly through the inhibition of STAT3 signaling. These results provide a novel insight into the role of sinomenine in the treatment of non-small cell lung cancer. PMID:27446441

  3. Blockade of STAT3 in T Cells Inhibits Germinal Center Reactions against Intranasal Allergens.

    PubMed

    Choi, Garam; Chung, Yeonseok

    2016-05-01

    Understanding the developmental mechanisms of humoral immunity against intranasal antigens is essential for the development of therapeutic approaches against air-borne pathogens as well as allergen-induced pulmonary inflammation. Follicular helper T (Tfh) cells expressing CXCR5 are required for humoral immunity by providing IL-21 and ICOS costimulation to activated B cells. However, the regulation of Tfh cell responses against intranasal antigens remains unclear. Here, we found that the generation of Tfh cells and germinal center B cells in the bronchial lymph node against intranasal proteinase antigens was independent of TGF-β. In contrast, administration of STAT3 inhibitor STA-21 suppressed the generation of Tfh cells and germinal center B cells. Compared with wild-type OT-II T cells, STAT3-deficient OT-II T cells transferred into recipients lacking T cells not only showed significantly reduced frequency Tfh cells, but also induced diminished IgG as well as IgE specific for the intranasal antigens. Cotransfer study of wild-type OT-II and STAT3-deficient OT-II T cells revealed that the latter failed to differentiate into Tfh cells. These findings demonstrate that T cell-intrinsic STAT3 is required for the generation of Tfh cells to intranasal antigens and that targeting STAT3 might be an effective approach to ameliorate antibody-mediated pathology in the lung.

  4. Merging Absolute and Relative Quantitative PCR Data to Quantify STAT3 Splice Variant Transcripts

    PubMed Central

    Turton, Keren B.; Esnault, Stephane; Delain, Larissa P.; Mosher, Deane F.

    2016-01-01

    Human signal transducer and activator of transcription 3 (STAT3) is one of many genes containing a tandem splicing site. Alternative donor splice sites 3 nucleotides apart result in either the inclusion (S) or exclusion (ΔS) of a single residue, Serine-701. Further downstream, splicing at a pair of alternative acceptor splice sites result in transcripts encoding either the 55 terminal residues of the transactivation domain (α) or a truncated transactivation domain with 7 unique residues (β). As outlined in this manuscript, measuring the proportions of STAT3's four spliced transcripts (Sα, Sβ, ΔSα and ΔSβ) was possible using absolute qPCR (quantitative polymerase chain reaction). The protocol therefore distinguishes and measures highly similar splice variants. Absolute qPCR makes use of calibrator plasmids and thus specificity of detection is not compromised for the sake of efficiency. The protocol necessitates primer validation and optimization of cycling parameters. A combination of absolute qPCR and efficiency-dependent relative qPCR of total STAT3 transcripts allowed a description of the fluctuations of STAT3 splice variants' levels in eosinophils treated with cytokines. The protocol also provided evidence of a co-splicing interdependence between the two STAT3 splicing events. The strategy based on a combination of the two qPCR techniques should be readily adaptable to investigation of co-splicing at other tandem splicing sites. PMID:27768061

  5. 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.

  6. 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; Huang, Jiansheng; Liu, Xiangyuan

    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.

  7. Suppression of epithelial apoptosis and delayed mammary gland involution in mice with a conditional knockout of Stat3

    PubMed Central

    Chapman, Rachel S.; Lourenco, Paula C.; Tonner, Elizabeth; Flint, David J.; Selbert, Stefan; Takeda, Kiyoshi; Akira, Shizuo; Clarke, Alan R.; Watson, Christine J.

    1999-01-01

    Mammary gland involution is characterized by extensive apoptosis of the epithelial cells. At the onset of involution, Stat3 is specifically activated. To address the function of this signaling molecule in mammary epithelial apoptosis, we have generated a conditional knockout of Stat3 using the Cre-lox recombination system. Following weaning, a decrease in apoptosis and a dramatic delay of involution occurred in Stat3 null mammary tissue. Involution is normally associated with a significant increase in IGFBP-5 levels. This was observed in control glands, but not in the absence of Stat3. IGFBP-5 has been suggested to induce apoptosis by sequestering IGF-1 to casein micelles, thereby inhibiting its survival function. Our findings suggest that IGFBP-5 is a direct or indirect target for Stat3 and its upregulation is essential to normal involution. No marked differences were seen in the regulation of Stat5, Bcl-xL, or Bax in the absence of Stat3. Precocious activation of Stat1 and increases in levels of p53 and p21 occurred and may act as compensatory mechanisms for the eventual initiation of involution observed in Stat3 null mammary glands. This is the first demonstration of the importance of a Stat factor in signaling the initiation of physiological apoptosis in vivo. PMID:10521404

  8. Role of STAT3 Phosphorylation in Ethanol-Mediated Proliferation of Breast Cancer Cells

    PubMed Central

    Narayanan, Poornima devi; Nandabalan, Sangeetha Kadapakkam

    2016-01-01

    Purpose In this study, we investigated the molecular mechanism involved in ethanol (EtOH)-mediated proliferation of breast cancer cells. Methods EtOH concentration was optimized by studying its effect on cell proliferation in MCF-7 and MDA MB-231 cells. We used flow cytometry and immunoblot analysis to evaluate the increased proliferation caused by the optimized concentrations of EtOH. The mechanism of EtOH-mediated proliferation was determined using reactive oxygen species (ROS) release assay, reverse transcription polymerase chain reaction, and immunoblot studies. Gene silencing followed by quantitative real-time polymerase chain reaction studies and inhibitor studies indicated the involvement of signal transducer and activator of transcription 3 (STAT3) in EtOH-mediated breast cancer proliferation. Results Exposure to EtOH caused an increase in cell proliferation and an accumulation of cells in S-phase in MCF-7 (347 µM EtOH) and MDA MB-231 (173 µM EtOH) cells. Additionally, increased release of ROS and the expression of pro-inflammatory cytokines, such as interleukin 6 and tumor necrosis factor α, confirmed that the proliferation was induced by the ROS-linked inflammatory response in breast cancer. The proinflammatory response was followed by phosphorylation of STAT3. The importance of STAT3 activation in EtOH-mediated proliferation was confirmed through the silencing of STAT3, followed by an investigation on the expression of cyclins and matrix metalloproteinases. Finally, studies using specific inhibitors indicated that the EtOH-mediated effect on STAT3 activation could be regulated by phosphoinositide-3-kinase and Janus kinase 2. Conclusion The study demonstrates the involvement of STAT3 signaling in EtOH-mediated breast cancer proliferation. PMID:27382387

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

    SciTech Connect

    Boku, Shuken; Nakagawa, Shin; Takamura, Naoki; Kato, Akiko; Takebayashi, Minoru; Hisaoka-Nakashima, Kazue; Omiya, Yuki; Inoue, Takeshi; Kusumi, Ichiro

    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.

  10. Niclosamide inhibition of STAT3 synergizes with erlotinib in human colon cancer

    PubMed Central

    Shi, Lingyi; Zheng, Hailun; Hu, Wanle; Zhou, Bin; Dai, Xuanxuan; Zhang, Yi; Liu, Zhiguo; Wu, Xiaoping; Zhao, Chengguang; Liang, Guang

    2017-01-01

    Niclosamide, an anthelmintic drug approved by the US Food and Drug Administration against cestodes, is used to treat tapeworm infection. In this study, we show that niclosamide can potentially inhibit signal transducer and activator of transcription 3 (STAT3) in colon cancer cell lines. Combined inhibition of epidermal growth factor receptor and STAT3 by erlotinib and niclosamide synergistically induces apoptosis and antiproliferation in colon cancer cell lines. Our findings suggest that erlotinib and niclosamide combination provides an effective therapeutic approach to improving the prognosis of colon cancer. PMID:28367059

  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. IL10R2 Overexpression Promotes IL22/STAT3 Signaling in Colorectal Carcinogenesis.

    PubMed

    Khare, Vineeta; Paul, Gregor; Movadat, Oliver; Frick, Adrian; Jambrich, Manuela; Krnjic, Anita; Marian, Brigitte; Wrba, Friedrich; Gasche, Christoph

    2015-11-01

    The mucosal immune response in the setting of intestinal inflammation contributes to colorectal cancer. IL10 signaling has a central role in gut homeostasis and is impaired in inflammatory bowel disease (IBD). Out of two IL10 receptor subunits, IL10R1 and IL10R2, the latter is shared among the IL10 family of cytokines and activates STAT signaling. STAT3 is oncogenic in colorectal cancer; however, knowledge about IL10 signaling upstream of STAT3 in colorectal cancer is lacking. Here, expression of IL10 signaling genes was examined in matched pairs from normal and tumor tissue from colorectal cancer patients showing overexpression (mRNA, protein) of IL10R2 and STAT3 but not IL10R1. IL10R2 overexpression was related to microsatellite stability. Transient overexpression of IL10R2 in HT29 cells increased proliferation upon ligand activation (IL10 and IL22). IL22, and not IL10, phosphorylated STAT3 along with increased phosphorylation of AKT and ERK. A significantly higher expression of IL22R1 and IL10R2 was also confirmed in a separate cohort of colorectal cancer samples. IL22 expression was elevated in gut mucosa from patients with IBD and colitis-associated cancer, which also exhibited increased expression of IL22R1 but not its coreceptor IL10R2. Overall, these data indicate that overexpression of IL10R2 and STAT3 contributes to colorectal carcinogenesis in microsatellite-stable tumors through IL22/STAT3 signaling.

  13. Ginkgetin induces apoptosis in 786-O cell line via suppression of JAK2-STAT3 pathway

    PubMed Central

    Ren, Yu; Huang, Shuang-shuang; Wang, Xue; Lou, Zhong-guan; Yao, Xu-ping; Weng, Guo-bin

    2016-01-01

    Objective(s): Renal cell carcinoma (RCC) is insensitive to conventional chemotherapy. Ginkgetin effectively treats several carcinoma cells. However, little is known about effects of Ginkgetin on RCC. In the present study, using 786-O cells, we evaluate whether Ginkgetin exerts anticancer effects against RCC. Materials and Methods: 786-O cells suspended in the medium containing Ginkgetin were cultured for 24 hr to 72 hr, and then MTT assay was used to study cytotoxic effect of Ginkgetin. Apoptosis in 786-O was measured by an FITC Annexin apoptosis detection kit. Protein expression was detected by Western blotting. 786-O cells with active Janus kinase 2 (JAK2)-Signal transducer and activator of transcription 3 (STAT3) were prepared by stimulant of interleukin-6 (IL-6), whereas 786-O cells with deactivated STAT3 were produced by small interfering RNA (siRNA) STAT3. Results: Ginkgetin suppressed the growth of 786-O in dose and time-dependent manners with IC50 values of 7.23 μM. Ginkgetin induced apoptosis of 786-O cells and increased the levels of caspase-8, caspase-9, and caspase-3. Additionally, Ginkgetin treated 786-O cells showed decreased levels of JAK2 and phosphorylated-STAT3 whether or not IL-6 was pretreated. Interestingly, pretreatment of siRNA STAT3 exerted inhibitory effects on the growth of 786-O cells, and the observation could be further reinforced after the Ginkgetin treatment. Conclusion: Our results indicate Ginkgetin possesses obvious inhibitory effects on the proliferation of 786-O, and this effect is probably due to its inhibition of JAK2/STAT3 pathway. Our findings imply Ginkgetin is a potential therapeutic medicine for RCC. PMID:27917282

  14. Benzoxathiol derivative BOT-4-one suppresses L540 lymphoma cell survival and proliferation via inhibition of JAK3/STAT3 signaling

    PubMed Central

    Kim, Byung Hak; Min, Yun Sook; Choi, Jung Sook; Baeg, Gyeong-Hun; Kim, Youngsoo; Shin, Jong Wook; Kim, Tae-Yoon

    2011-01-01

    Persistently activated JAK/STAT3 signaling pathway plays a pivotal role in various human cancers including major carcinomas and hematologic tumors, and is implicated in cancer cell survival and proliferation. Therefore, inhibition of JAK/STAT3 signaling may be a clinical application in cancer therapy. Here, we report that 2-cyclohexylimino-6-methyl-6,7-dihydro-5H-benzo [1,3]oxathiol-4-one (BOT-4-one), a small molecule inhibitor of JAK/STAT3 signaling, induces apoptosis through inhibition of STAT3 activation. BOT-4-one suppressed cytokine (upd)-induced tyrosine phosphorylation and transcriptional activity of STAT92E, the sole Drosophila STAT homolog. Consequently, BOT-4-one significantly inhibited STAT3 tyrosine phosphorylation and expression of STAT3 downstream target gene SOCS3 in various human cancer cell lines, and its effect was more potent in JAK3-activated Hodgkin's lymphoma cell line than in JAK2-activated breast cancer and prostate cancer cell lines. In addition, BOT-4-one-treated Hodgkin's lymphoma cells showed decreased cell survival and proliferation by inducing apoptosis through down-regulation of STAT3 downstream target anti-apoptotic gene expression. These results suggest that BOT-4-one is a novel small molecule inhibitor of JAK3/STAT3 signaling and may have therapeutic potential in the treatment of human cancers harboring aberrant JAK3/STAT3 signaling, specifically Hodgkin's lymphoma. PMID:21499010

  15. Benzoxathiol derivative BOT-4-one suppresses L540 lymphoma cell survival and proliferation via inhibition of JAK3/STAT3 signaling.

    PubMed

    Kim, Byung Hak; Min, Yun Sook; Choi, Jung Sook; Baeg, Gyeong Hun; Kim, Young Soo; Shin, Jong Wook; Kim, Tae Yoon; Ye, Sang Kyu

    2011-05-31

    Persistently activated JAK/STAT3 signaling pathway plays a pivotal role in various human cancers including major carcinomas and hematologic tumors, and is implicated in cancer cell survival and proliferation. Therefore, inhibition of JAK/STAT3 signaling may be a clinical application in cancer therapy. Here, we report that 2-cyclohexylimino-6-methyl-6,7-dihydro-5H-benzo [1,3]oxathiol-4-one (BOT-4-one), a small molecule inhibitor of JAK/STAT3 signaling, induces apoptosis through inhibition of STAT3 activation. BOT-4-one suppressed cytokine (upd)-induced tyrosine phosphorylation and transcriptional activity of STAT92E, the sole Drosophila STAT homolog. Consequently, BOT-4-one significantly inhibited STAT3 tyrosine phosphorylation and expression of STAT3 downstream target gene SOCS3 in various human cancer cell lines, and its effect was more potent in JAK3-activated Hodgkin's lymphoma cell line than in JAK2-activated breast cancer and prostate cancer cell lines. In addition, BOT-4-one-treated Hodgkin's lymphoma cells showed decreased cell survival and proliferation by inducing apoptosis through down-regulation of STAT3 downstream target anti-apoptotic gene expression. These results suggest that BOT-4-one is a novel small molecule inhibitor of JAK3/STAT3 signaling and may have therapeutic potential in the treatment of human cancers harboring aberrant JAK3/STAT3 signaling, specifically Hodgkin's lymphoma.

  16. Ablation of Stat3 by siRNA alters gene expression profiles in JEG-3 cells: a systems biology approach.

    PubMed

    Jiang, K; Krous, L C; Knowlton, N; Chen, Y; Frank, M B; Cadwell, C; Centola, M; Jarvis, J N

    2009-09-01

    Control of inflammation at the maternal-fetal interface is a critical element in mammalian pregnancy. Previous work from our laboratory has shown that Stat3 may be a placental mediator involved in maintaining immunologic homeostasis at the maternal-fetal interface. The aim of the current study is to further elucidate the role of Stat3 in response to inflammation. As ablation of Stat3 in mice results in embryonic lethality, we evaluated the role of Stat3 in vitro using an siRNA approach. Trophoblast-like JEG-3 cells were transfected with an siRNA construct specific to Stat3. Experimental and control cells were exposed to conditioned medium from PHA-activated peripheral blood mononuclear cells and incubated for 45 min. Cells were then collected and RNA isolated for transcriptional profiling using human Affymetrix U133 plus 2.0 GeneChips. Differences in gene expression between control and Stat3-ablated cells were evaluated using conventional statistical methods. Fifty-two genes were detected as up-regulated in conditioned medium in both mock transfected and in Stat3 siRNA transfected JEG-3 cells. Two genes (EPAS1 and RASGEF1B) were up-regulated only in cells transfected with negative control siRNA, while 36 genes were up-regulated only in cells transfected with Stat3 siRNA. Sixty genes were differentially expressed between Stat3 siRNA transfected cells relative to mock transfected cells both in basal and conditioned medium. These included 31 genes up-regulated with Stat3 siRNA transfected cells and 29 genes down-regulated with Stat3 siRNA. Eleven genes were differentially expressed only in basal medium. Seven of these were up-regulated in the presence of Stat3 siRNA and four were down-regulated. Nine genes were differentially expressed only in conditioned medium. Six of these were up-regulated and three down-regulated in the presence of Stat3 siRNA. Off-target effects were excluded in a second set of experiments in which Stat3 mRNA was targeted at a different site and

  17. The Ubiquitin Ligase TRAF6 Negatively Regulates the JAK-STAT Signaling Pathway by Binding to STAT3 and Mediating Its Ubiquitination

    PubMed Central

    Jin, Chaozhi; Chen, Hui; Leng, Ling; He, Fuchu; Wang, Jian

    2012-01-01

    STAT3 is a key transcription factor that mediates various cellular and organismal processes, such as cell growth, apoptosis, immune response and cancer. However, the molecular mechanisms of STAT3 regulation remain poorly understood. Here, we identified TRAF6 as a new STAT3 interactor. TRAF6 augmented the ubiquitination of STAT3 and deactivated its transcriptional activity induced by IFNα stimulation or overexpressed with JAK2. Both the RING domain and the TRAF-type zinc finger domain of TRAF6 were indispensable for STAT3 deactivation. Accordingly, TRAF6 also down-regulated the expression of two known STAT3 target genes, CRP and ACT. Therefore, we showed that TRAF6 is a new regulator of JAK/STAT signaling and provide a new mechanistic explanation for the crosstalk between the NF-κB and the JAK-STAT pathways. PMID:23185365

  18. BCL3 exerts an oncogenic function by regulating STAT3 in human cervical cancer

    PubMed Central

    Zhao, Hu; Wang, Wuliang; Zhao, Qinghe; Hu, Guiming; Deng, Kehong; Liu, Yuling

    2016-01-01

    Aberrant expression of oncogenes and/or tumor suppressors play a fundamental effect on the pathogenesis and tumorigenicity of cervical cancer (CC). B-cell CLL/lymphoma 3 (BCL3) was previously found to be a putative proto-oncogene in human cancers and regulated signal transducer and activator of transcription 3 (STAT3), a critical oncogene, in CC cell line. However, its expression status, clinical significance and biological functions in CC remain largely unclear. The expressions of BCL3 and STAT3 in CC specimens were determined by immunohistochemistry. MTT, colony formation assays and flow cytometry analysis were carried out to test proliferation and cell cycle of CC cells. Here, the levels of BCL3 were overexpressed in CC compared to adjacent cervical tissues. Furthermore, high levels of BCL3 protein were confirmed by immunoblotting in CC cells as compared with normal cervical epithelial cells. The positive expression of BCL3 was correlated with adverse prognostic features and reduced survival rate. In addition, BCL3 regulated STAT3 abundance in CC cells. STAT3 was found to be upregulated and positively correlated with BCL3 expression in CC specimens. BCL3 overexpression resulted in prominent increased proliferation and cell cycle progression in Hela cells. By contrast, inhibition of BCL3 in CaSki cells remarkably suppressed proliferative ability and cell cycle progression. In vivo studies showed that knockdown of BCL3 inhibited tumor growth of CC in mice xenograft model. Notably, we confirmed that STAT3 mediated the oncogenic roles of BCL3 in CC. In conclusion, we suggest that BCL3 serves as an oncogene in CC by modulating proliferation and cell cycle progression, and its oncogenic effect is mediated by its downstream target gene, STAT3. PMID:27822067

  19. Targeting Stat3 induces senescence in tumor cells and elicits prophylactic and therapeutic immune responses against breast cancer growth mediated by NK cells and CD4+ T cells.

    PubMed

    Tkach, Mercedes; Coria, Lorena; Rosemblit, Cinthia; Rivas, Martín A; Proietti, Cecilia J; Díaz Flaqué, María Celeste; Beguelin, Wendy; Frahm, Isabel; Charreau, Eduardo H; Cassataro, Juliana; Elizalde, Patricia V; Schillaci, Roxana

    2012-08-01

    Aberrant Stat3 activation and signaling contribute to malignant transformation by promoting cell cycle progression, inhibiting apoptosis, and mediating tumor immune evasion. Stat3 inhibition in tumor cells induces the expression of chemokines and proinflammatory cytokines, so we proposed to apply Stat3-inhibited breast cancer cells as a source of immunogens to induce an antitumor immune response. Studies were performed in two murine breast cancer models in which Stat3 is activated: progestin-dependent C4HD cells and 4T1 cells. We immunized BALB/c mice with irradiated cancer cells previously transfected with a dominant-negative Stat3 vector (Stat3Y705F) in either a prophylactic or a therapeutic manner. Prophylactic administration of breast cancer cells transfected with Stat3Y705F (Stat3Y705F-breast cancer cells) inhibited primary tumor growth compared with administration of empty vector-transfected cells in both models. In the 4T1 model, 50% of the challenged mice were tumor free, and the incidence of metastasis decreased by 90%. In vivo assays of C4HD tumors showed that the antitumor immune response involves the participation of CD4(+) T cells and cytotoxic NK cells. Therapeutic immunization with Stat3Y705F-breast cancer cells inhibited tumor growth, promoted tumor cell differentiation, and decreased metastasis. Furthermore, inhibition of Stat3 activation in breast cancer cells induced cellular senescence, contributing to their immunogenic phenotype. In this work, we provide preclinical proof of concept that ablating Stat3 signaling in breast cancer cells results in an effective immunotherapy against breast cancer growth and metastasis. Moreover, our findings showing that Stat3 inactivation results in induction of a cellular senescence program disclose a potential mechanism for immunotherapy research.

  20. Heme oxygenase-1 induction attenuates imiquimod-induced psoriasiform inflammation by negative regulation of Stat3 signaling.

    PubMed

    Zhang, Bin; Xie, Sijing; Su, Zhonglan; Song, Shiyu; Xu, Hui; Chen, Gang; Cao, Wangsen; Yin, Shasha; Gao, Qian; Wang, Hongwei

    2016-02-19

    Heme oxygenase-1 (HO-1), a stress-inducible protein with a potential anti-inflammatory effect, plays an important role in skin injury and wound healing. However, the function of HO-1 in cutaneous inflammatory diseases, such as psoriasis, remains unknown. The abnormal activation of Stat3, a known transcription factor that induces inflammation and regulates cell differentiation, is directly involved in the pathogenesis and development of psoriasis. Hence, targeting Stat3 is potentially beneficial in the treatment of psoriasis. In this study, HO-1 activation significantly alleviated the disease-related pathogenesis abnormality. To determine the mechanism by which HO-1 exerts immune protection on Th17-related cytokines, IL6/IL22-induced Stat3 activation was significantly suppressed, accompanied by decreased cell proliferation and reversed abnormal cell proliferation. Importantly, HO-1-induced Stat3 suppression was mediated through the activation of protein tyrosine phosphatase SHP-1. Overall, our study provides direct evidence indicating that HO-1 might be a useful therapeutic target for psoriasis. SHP-1-mediated suppression of Stat3 activation after HO-1 activation is a unique molecular mechanism for the regulation of Stat3 activation.

  1. STAT3 signaling pathway is necessary for cell survival and tumorsphere forming capacity in ALDH{sup +}/CD133{sup +} stem cell-like human colon cancer cells

    SciTech Connect

    Lin, Li; Fuchs, James; Li, Chenglong; Olson, Veronica; Bekaii-Saab, Tanios; Lin, Jiayuh

    2011-12-16

    Highlights: Black-Right-Pointing-Pointer The phosphorylated or activated form of STAT3 was expressed in colon cancer stem-like cells. Black-Right-Pointing-Pointer STAT3 inhibitor, FLLL32 inhibits P-STAT3 and STAT3 target genes in colon cancer stem-like cells. Black-Right-Pointing-Pointer Inhibition of STAT3 resulted in decreased cell viability and reduced numbers of tumorspheres. Black-Right-Pointing-Pointer STAT3 is required for survival and tumorsphere forming capacity in colon cancer stem-like cells. Black-Right-Pointing-Pointer Targeting STAT3 in cancer stem-like cells may offer a novel treatment approach for colon cancer. -- Abstract: Persistent activation of Signal Transducers and Activators of Transcription 3 (STAT3) is frequently detected in colon cancer. Increasing evidence suggests the existence of a small population of colon cancer stem or cancer-initiating cells may be responsible for tumor initiation, metastasis, and resistance to chemotherapy and radiation. Whether STAT3 plays a role in colon cancer-initiating cells and the effect of STAT3 inhibition is still unknown. Flow cytometry was used to isolate colon cancer stem-like cells from three independent human colon cancer cell lines characterized by both aldehyde dehydrogenase (ALDH)-positive and CD133-positive subpopulation (ALDH{sup +}/CD133{sup +}). The effects of STAT3 inhibition in colon cancer stem-like cells were examined. The phosphorylated or activated form of STAT3 was expressed in colon cancer stem-like cells and was reduced by a STAT3-selective small molecular inhibitor, FLLL32. FLLL32 also inhibited the expression of potential STAT3 downstream target genes in colon cancer stem-like cells including survivin, Bcl-XL, as well as Notch-1, -3, and -4, which may be involved in stem cell function. Furthermore, FLLL32 inhibited cell viability and tumorsphere formation as well as induced cleaved caspase-3 in colon cancer stem-like cells. FLLL32 is more potent than curcumin as evidenced with lower

  2. Tofacitinib regulates synovial inflammation in psoriatic arthritis, inhibiting STAT activation and induction of negative feedback inhibitors

    PubMed Central

    Gao, W; McGarry, T; Orr, C; McCormick, J; Veale, D J; Fearon, U

    2016-01-01

    Background Psoriatic arthritis (PsA) is a chronic inflammatory disease, characterised by synovitis and destruction of articular cartilage/bone. Janus-kinase and signal transducer and activator of transcription (JAK-STAT) signalling pathway is implicated in the pathogenesis of PsA. Objectives To examine the effect of tofacitinib (JAK inhibitor) on proinflammatory mechanisms in PsA. Methods Primary PsA synovial fibroblasts (PsAFLS) and ex vivo PsA synovial explants were cultured with tofacitinib (1 µM). PhosphoSTAT3 (pSTAT3), phosphoSTAT1 (pSTAT1), suppressor of cytokine signaling-3 (SOCS3), protein inhibitor of activated Stat3 (PIAS3) and nuclear factor kappa B cells (NFκBp65) were quantified by western blot. The effect of tofacitinib on PsAFLS migration, invasion, Matrigel network formation and matrix metallopeptidase (MMP)2/9 was quantified by invasion/migration assays and zymography. Interleukin (IL)-6, IL-8, IFN-gamma-inducible protein 10 (IP-10) monocyte chemoattractant protein (MCP)-1, IL-17, IL-10, MMP3 and tissue inhibitor of metalloproteinases 3 (TIMP3) were assessed by ELISA. Results Tofacitinib significantly decreased pSTAT3, pSTAT1, NFκBp65 and induced SOCS3 and PIAS3 expression in PsAFLS and synovial explant cultures (p<0.05). Functionally, PsAFLS invasion, network formation and migration were inhibited by tofacitinib (all p<0.05). In PsA explant, tofacitinib significantly decreased spontaneous secretion of IL-6, IL-8, MCP-1, MMP9/MMP2, MMP3 (all p<0.05) and decreased the MMP3/TIMP3 ratio (p<0.05), with no effect observed for IP-10 or IL-10. Conclusions This study further supports JAK-STAT inhibition as a therapeutic target for the treatment of PsA. PMID:26353790

  3. LYR71, a derivative of trimeric resveratrol, inhibits tumorigenesis by blocking STAT3-mediated matrix metalloproteinase 9 expression

    PubMed Central

    Kim, Ja Eun; Kim, Hong Sook; Shin, Yong-Jae; Lee, Chang Seok; Won, Cheolhee; Lee, Sin-Ae; Lee, Jung Weon; Kim, Youngsoo; Kang, Jae-Seung; Chung, Myung-Hee

    2008-01-01

    Tumor migration/invasion is the main cause of tumor progression and STAT3 is needed to enhance tumor migration/invasion by up-regulating MMP-9. Thus, agents that inhibit STAT3 activation may be used as an anticancer drug. We present herein that 6-methyl-2-propylimino-6, 7-dihydro-5H-benzo [1, 3]-oxathiol-4-one (LYR71) , a derivative of trimeric resveratrol, has an anticancer activity through inhibition of STAT3 activation. We found that LYR71 suppressed STAT3 activation and inhibited the expression and activity of MMP-9 in RANTES-stimulated breast cancer cells. In addition, LYR71 reduced RANTES-induced MMP-9 transcripts by blocking STAT3 recruitment, dissociating p300 and deacetylating histone H3 and H4 on the MMP-9 promoter. Furthermore, LYR71 inhibited tumor migration/invasion in RANTES-treated breast cancer cells and consequently blocked tumor progression in tumor-bearing mice. Taken together, the results of this study suggest that LYR71 can be therapeutically useful due to the inhibition effect of STAT3-mediated MMP-9 expression in breast cancer cells. PMID:18985009

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

    PubMed Central

    Shin, Minkyung; Yi, Eun Hee; Kim, Byung-Hak; Shin, Jae-Cheon; Park, Jung Youl; Cho, Chung-Hyun; Park, Jong-Wan; Choi, Kang-Yell; Ye, Sang-Kyu

    2016-01-01

    The β-catenin functions as an adhesion molecule and a component of the Wnt signaling pathway. In the absence of the Wnt ligand, β-catenin is constantly phosphorylated, which designates it for degradation by the APC complex. This process is one of the key regulatory mechanisms of β-catenin. The level of β-catenin is also controlled by the E3 ubiquitin protein ligase SIAH-1 via a phosphorylation-independent degradation pathway. Similar to β-catenin, STAT3 is responsible for various cellular processes, such as survival, proliferation, and differentiation. However, little is known about how these molecules work together to regulate diverse cellular processes. In this study, we investigated the regulatory relationship between STAT3 and β-catenin in HEK293T cells. To our knowledge, this is the first study to report that β-catenin-TCF-4 transcriptional activity was suppressed by phosphorylated STAT3; furthermore, STAT3 inactivation abolished this effect and elevated activated β-catenin levels. STAT3 also showed a strong interaction with SIAH-1, a regulator of active β-catenin via degradation, which stabilized SIAH-1 and increased its interaction with β-catenin. These results suggest that activated STAT3 regulates active β-catenin protein levels via stabilization of SIAH-1 and the subsequent ubiquitin-dependent proteasomal degradation of β-catenin in HEK293T cells. PMID:27871173

  5. Protein Tyrosine Phosphatases, TC-PTP, SHP1, and SHP2, Cooperate in Rapid Dephosphorylation of Stat3 in Keratinocytes Following UVB Irradiation

    PubMed Central

    Kim, Dae Joon; Tremblay, Michel L.; DiGiovanni, John

    2010-01-01

    Stat3 is initially dephosphorylated in murine keratinocytes in response to UVB irradiation. Treatment with Na3VO4 desensitized keratinocytes to UVB-induced apoptosis with the recovery of phosphorylated Stat3 protein levels, implying that a protein tyrosine phosphatase (PTP) is involved in this mechanism. In the current work, we report that three PTPs including TC45 (the nuclear form of TC-PTP), SHP1, and SHP2 are involved in this rapid dephosphorylation of Stat3 in keratinocytes induced by UVB irradiation. Dephosphorylation of Stat3 was increased rapidly after UVB irradiation of cultured keratinocytes. Knockdown of TC-PTP, SHP1, or SHP2 using RNAi showed that these PTPs are likely responsible for most of the rapid Stat3 dephosphorylation observed following UVB irradiation. The level of phosphorylated Stat3 was significantly higher in keratinocytes transfected with TC-PTP, SHP1, or SHP2 siRNA in the presence or absence of UVB compared with keratinocytes transfected with control siRNA. TC45 was mainly localized in the cytoplasm of keratinocytes and translocated from cytoplasm to nucleus upon UVB irradiation. Stat3 dephosphorylation was associated with nuclear translocation of TC45. Further studies revealed that knockdown of all three phosphatases, using RNAi, prevented the rapid dephosphorylation of Stat3 following UVB irradiation. In mouse epidermis, the level of phosphorylated Stat3 was initially decreased, followed by a significant increase at later time points after UVB exposure. The levels of Stat3 target genes, such as cyclin D1 and c-Myc, followed the changes in activated Stat3 in response to UVB irradiation. Collectively, these results suggest that three phosphatases, TC45, SHP1, and SHP2, are primarily responsible for UVB-mediated Stat3 dephosphorylation and may serve as part of an initial protective mechanism against UV skin carcinogenesis. PMID:20421975

  6. Curcuminoid-phospholipid complex induces apoptosis in mammary epithelial cells by STAT-3 signaling

    PubMed Central

    Cucuzza, Laura Starvaggi; Motta, Massimiliano; Miretti, Silvia; Accornero, Paolo

    2008-01-01

    Curcumin (from the rhizome of Curcuma longa) is well documented for its medicinal properties in Indian and Chinese systems of medicine where it is widely used for the treatment of several diseases. Epidemiological observations are suggestive that curcumin consumption may reduce the risk of some form of cancers and provide other protective biological effects in humans. These biological properties have been attributed to curcuminoids that have been widely studied for their anti-inflammatory, anti-angiogenic, antioxidant, wound healing and anti-cancer effects. In this study we have investigated on the effect of a curcumin phospholipid complex on mammary epithelial cell viability. HC11 and BME-UV cell lines, validated models to study biology of normal, not tumoral, mammary epithelial cells, were used to analyse these effects. We report that curcumin acts on STAT-3 signal pathway to reduce cell viability and increase apoptosis evaluated by the the amount of activated caspase 3. Further it reduces MAPK and AKT activations. JSI-124, a STAT-3 inhibitor (100 nM) was able to block the negative effect of curcumin on cell viability and caspase 3 activation. Finally the negative effect of cucumin on cell viability has been impaired in STAT-3i HC11, where STAT-3 protein was greatly reduced by shRNA-interference. These results indicate that curcumin presents a potential adverse effect to normal mammary epithelial cells and that it has a specific effect on signal trasduction in mammary epithelium. PMID:19116450

  7. IL-17 promotes tumor angiogenesis through Stat3 pathway mediated upregulation of VEGF in gastric cancer.

    PubMed

    Wu, Xiaoqin; Yang, Tao; Liu, Xiang; Guo, Jia Nian; Xie, Tingting; Ding, Yuanwei; Lin, Manpeng; Yang, Hui

    2016-04-01

    Gastric cancer is the world's second most common malignancy and is a major threat to global health. IL-17, a CD4 T cell-derived mediator of angiogenesis, plays a major role in stimulating angiogenesis by regulating the production of a variety of proangiogenic factors, including the vascular endothelial growth factor (VEGF). The level of VEGF expression correlates with tumor progression and metastasis in gastric cancer tissues. Abnormal activation of signal transducer and activator of transcription 3 (Stat3) rendered the tumor cells highly angiogenic, which is manifested by an increased microvascular density (MVD) and considered it as a potential molecular marker for poor prognosis in gastric cancer angiogenesis. We determined that IL-17A-induced VEGF upregulation and neovascularization through a Stat3-mediated signaling pathway and hypothesized that blocking the Stat3 activation by using JSI-124, an inhibitor of phosphorylated Stat3, could significantly reduce the VEGF expression and can thus prevent angiogenesis. We showed an inhibition of angiogenesis and tumor progression when JSI-124 was treated with IL-17A in the cells and xenografts in an animal model and suggested that targeting the Stat pathway with JSI-124 could derive an effective therapeutic target for gastric cancers and could be a promising drug in gastric cancer treatment.

  8. Patrinia scabiosaefolia extract suppresses proliferation and promotes apoptosis by inhibiting the STAT3 pathway in human multiple myeloma cells.

    PubMed

    Peng, Jun; Chen, Youqin; Lin, Jiumao; Zhuang, Qunchuan; Xu, Wei; Hong, Zhenfeng; Sferra, Thomas J

    2011-01-01

    Signal transducer and activator of transcription 3 (STAT3) plays an important role in tumor cell survival and proliferation and thus has become a major focus in the development of anti-cancer therapies. Patrinia scabiosaefolia has been used for the treatment of various types of cancer. However, the precise mechanism of the anti-cancer activity of Patrinia scabiosaefolia remains unclear. In this study, we evaluated the effect of the ethanol extract of Patrinia scabiosaefolia (EEPS) on proliferation and apoptosis in human multiple myeloma U266 cells that persistently express phosphorylated STAT3, and investigated the possible molecular mechanisms mediating its biological effects. We found that EEPS inhibited the phosphorylation of STAT3 in U266 cells. Consequently, the inhibitory effect of EEPS on STAT3 activation resulted in the suppression of cell proliferation and the induction of cell apoptosis. Moreover, EEPS treatment inhibited the expression of cyclin D1 (a promoter of cell proliferation) and Bcl-2 (an inhibitor of apoptosis), two important target genes of the STAT3 signaling pathway. Our findings for the first time demonstrate that Patrinia scabiosaefolia inhibits proliferation and promotes the apoptosis of cancer cells via inhibition of the STAT3 pathway, which may in part explain its anti-cancer activity.

  9. The histone deacetylase inhibitor valproic acid inhibits NKG2D expression in natural killer cells through suppression of STAT3 and HDAC3

    PubMed Central

    Ni, Lulu; Wang, Lixin; Yao, Chao; Ni, Zhongya; Liu, Fei; Gong, Chenyuan; Zhu, Xiaowen; Yan, Xuewei; Watowich, Stephanie S.; Lee, Dean A.; Zhu, Shiguo

    2017-01-01

    NKG2D is a major activating receptor of NK cells and plays a critical role in tumor immunosurveillance. NKG2D expression in NK cells is inhibited by the histone deacetylase (HDAC) inhibitor valproic acid (VPA) and enhanced by the narrow-spectrum HDAC inhibitor entinostat. We previously demonstrated that entinostat enhanced NKG2D transcription by increasing acetylation of Histones H3 and H4. However, the mechanism by which VPA reduces NKG2D expression in NK cells is not known. We have also shown that NKG2D transcription is regulated by STAT3 phosphorylation. In this study, we investigated regulation of NKG2D expression in NK cells by VPA and entinostat by assessing protein expression, phosphorylation, and interaction of HDACs and STAT3. We find that VPA selectively inhibits STAT3 tyrosine705 phosphorylation, but entinostat does not. STAT3 complexes with HDAC3, and HDAC3 inhibition represses STAT3 phosphorylation and therefore NKG2D expression. NK cells from STAT3 wild-type mice downregulate NKG2D in response to VPA, but not NK cells from STAT3 knockout mice. These results show that VPA is a potent inhibitor of STAT3 phosphorylation and demonstrate that histone acetylation and STAT3 tyrosine705 phosphorylation cooperate in regulating NKG2D expression in NK cells. PMID:28338101

  10. The Akt1/IL-6/STAT3 pathway regulates growth of lung tumor initiating cells

    PubMed Central

    Malanga, Donatella; De Marco, Carmela; Guerriero, Ilaria; Colelli, Fabiana; Rinaldo, Nicola; Scrima, Marianna; Mirante, Teresa; De Vitis, Claudia; Zoppoli, Pietro; Ceccarelli, Michele; Riccardi, Miriam; Ravo, Maria; Weisz, Alessandro; Federico, Antonella; Franco, Renato; Rocco, Gaetano; Mancini, Rita; Rizzuto, Antonia; Gulletta, Elio; Ciliberto, Gennaro; Viglietto, Giuseppe

    2015-01-01

    Here we report that the PI3K/Akt1/IL-6/STAT3 signalling pathway regulates generation and stem cell-like properties of Non-Small Cell Lung Cancer (NSCLC) tumor initiating cells (TICs). Mutant Akt1, mutant PIK3CA or PTEN loss enhances formation of lung cancer spheroids (LCS), self-renewal, expression of stemness markers and tumorigenic potential of human immortalized bronchial cells (BEAS-2B) whereas Akt inhibition suppresses these activities in established (NCI-H460) and primary NSCLC cells. Matched microarray analysis of Akt1-interfered cells and LCSs identified IL-6 as a critical target of Akt signalling in NSCLC TICs. Accordingly, suppression of Akt in NSCLC cells decreases IL-6 levels, phosphorylation of IkK and IkB, NF-kB transcriptional activity, phosphorylation and transcriptional activity of STAT3 whereas active Akt1 up-regulates them. Exposure of LCSs isolated from NSCLC cells to blocking anti-IL-6 mAbs, shRNA to IL-6 receptor or to STAT3 markedly reduces the capability to generate LCSs, to self-renew and to form tumors, whereas administration of IL-6 to Akt-interfered cells restores the capability to generate LCSs. Finally, immunohistochemical studies in NSCLC patients demonstrated a positive correlative trend between activated Akt, IL-6 expression and STAT3 phosphorylation (n = 94; p < 0.05). In conclusion, our data indicate that aberrant Akt signalling contributes to maintaining stemness in lung cancer TICs through a NF-kB/IL-6/STAT3 pathway and provide novel potential therapeutic targets for eliminating these malignant cells in NSCLC. PMID:26486080

  11. The Akt1/IL-6/STAT3 pathway regulates growth of lung tumor initiating cells.

    PubMed

    Malanga, Donatella; De Marco, Carmela; Guerriero, Ilaria; Colelli, Fabiana; Rinaldo, Nicola; Scrima, Marianna; Mirante, Teresa; De Vitis, Claudia; Zoppoli, Pietro; Ceccarelli, Michele; Riccardi, Miriam; Ravo, Maria; Weisz, Alessandro; Federico, Antonella; Franco, Renato; Rocco, Gaetano; Mancini, Rita; Rizzuto, Antonia; Gulletta, Elio; Ciliberto, Gennaro; Viglietto, Giuseppe

    2015-12-15

    Here we report that the PI3K/Akt1/IL-6/STAT3 signalling pathway regulates generation and stem cell-like properties of Non-Small Cell Lung Cancer (NSCLC) tumor initiating cells (TICs). Mutant Akt1, mutant PIK3CA or PTEN loss enhances formation of lung cancer spheroids (LCS), self-renewal, expression of stemness markers and tumorigenic potential of human immortalized bronchial cells (BEAS-2B) whereas Akt inhibition suppresses these activities in established (NCI-H460) and primary NSCLC cells. Matched microarray analysis of Akt1-interfered cells and LCSs identified IL-6 as a critical target of Akt signalling in NSCLC TICs. Accordingly, suppression of Akt in NSCLC cells decreases IL-6 levels, phosphorylation of IkK and IkB, NF-kB transcriptional activity, phosphorylation and transcriptional activity of STAT3 whereas active Akt1 up-regulates them. Exposure of LCSs isolated from NSCLC cells to blocking anti-IL-6 mAbs, shRNA to IL-6 receptor or to STAT3 markedly reduces the capability to generate LCSs, to self-renew and to form tumors, whereas administration of IL-6 to Akt-interfered cells restores the capability to generate LCSs. Finally, immunohistochemical studies in NSCLC patients demonstrated a positive correlative trend between activated Akt, IL-6 expression and STAT3 phosphorylation (n = 94; p < 0.05). In conclusion, our data indicate that aberrant Akt signalling contributes to maintaining stemness in lung cancer TICs through a NF-kB/IL-6/STAT3 pathway and provide novel potential therapeutic targets for eliminating these malignant cells in NSCLC.

  12. TRPM7 channels regulate glioma stem cell through STAT3 and Notch signaling pathways.

    PubMed

    Liu, Mingli; Inoue, Koichi; Leng, Tiandong; Guo, Shanchun; Xiong, Zhi-gang

    2014-12-01

    Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor in adults with median survival time of 14.6 months. A small fraction of cancer stem cells (CSC) initiate and maintain tumors thus driving glioma tumorigenesis and being responsible for resistance to classical chemo- and radio-therapies. It is desirable to identify signaling pathways related to CSC to develop novel therapies to selectively target them. Transient receptor potential cation channel, subfamily M, member 7, also known as TRPM7 is a ubiquitous, Ca(2+) and Mg(2+) permeable ion channels that are special in being both an ion channel and a serine/threonine kinase. In studies of glioma cells silenced for TRPM7, we demonstrated that Notch (Notch1, JAG1, Hey2, and Survivin) and STAT3 pathways are down regulated in glioma cells grown in monolayer. Furthermore, phospho-STAT3, Notch target genes and CSC markers (ALDH1 and CD133) were significantly higher in spheroid glioma CSCs when compared with monolayer cultures. The results further show that tyrosine-phosphorylated STAT3 binds and activates the ALDH1 promoters in glioma cells. We found that TRMP7-induced upregulation of ALDH1 expression is associated with increases in ALDH1 activity and is detectable in stem-like cells when expanded as spheroid CSCs. Finally, TRPM7 promotes proliferation, migration and invasion of glioma cells. These demonstrate that TRPM7 activates JAK2/STAT3 and/or Notch signaling pathways and leads to increased cell proliferation and migration. These findings for the first time demonstrates that TRPM7 (1) activates a previously unrecognized STAT3→ALDH1 pathway, and (2) promotes the induction of ALDH1 activity in glioma cells.

  13. Quantifying the dynamics of the oligomeric transcription factor STAT3 by pair correlation of molecular brightness.

    PubMed

    Hinde, Elizabeth; Pandžić, Elvis; Yang, Zhengmin; Ng, Ivan H W; Jans, David A; Bogoyevitch, Marie A; Gratton, Enrico; Gaus, Katharina

    2016-03-24

    Oligomerization of transcription factors controls their translocation into the nucleus and DNA-binding activity. Here we present a fluorescence microscopy analysis termed pCOMB (pair correlation of molecular brightness) that tracks the mobility of different oligomeric species within live cell nuclear architecture. pCOMB amplifies the signal from the brightest species present and filters the dynamics of the extracted oligomeric population based on arrival time between two locations. We use this method to demonstrate a dependence of signal transducer and activator of transcription 3 (STAT3) mobility on oligomeric state. We find that on entering the nucleus STAT3 dimers must first bind DNA to form STAT3 tetramers, which are also DNA-bound but exhibit a different mobility signature. Examining the dimer-to-tetramer transition by a cross-pair correlation analysis (cpCOMB) reveals that chromatin accessibility modulates STAT3 tetramer formation. Thus, the pCOMB approach is suitable for mapping the impact oligomerization on transcription factor dynamics.

  14. Quantifying the dynamics of the oligomeric transcription factor STAT3 by pair correlation of molecular brightness

    PubMed Central

    Hinde, Elizabeth; Pandžić, Elvis; Yang, Zhengmin; Ng, Ivan H. W.; Jans, David A.; Bogoyevitch, Marie A.; Gratton, Enrico; Gaus, Katharina

    2016-01-01

    Oligomerization of transcription factors controls their translocation into the nucleus and DNA-binding activity. Here we present a fluorescence microscopy analysis termed pCOMB (pair correlation of molecular brightness) that tracks the mobility of different oligomeric species within live cell nuclear architecture. pCOMB amplifies the signal from the brightest species present and filters the dynamics of the extracted oligomeric population based on arrival time between two locations. We use this method to demonstrate a dependence of signal transducer and activator of transcription 3 (STAT3) mobility on oligomeric state. We find that on entering the nucleus STAT3 dimers must first bind DNA to form STAT3 tetramers, which are also DNA-bound but exhibit a different mobility signature. Examining the dimer-to-tetramer transition by a cross-pair correlation analysis (cpCOMB) reveals that chromatin accessibility modulates STAT3 tetramer formation. Thus, the pCOMB approach is suitable for mapping the impact oligomerization on transcription factor dynamics. PMID:27009358

  15. Human metapneumovirus inhibits the IL-6-induced JAK/STAT3 signalling cascade in airway epithelium.

    PubMed

    Mitzel, Dana N; Jaramillo, Richard J; Stout-Delgado, Heather; Senft, Albert P; Harrod, Kevin S

    2014-01-01

    The host cytokine IL-6 plays an important role in host defence and prevention of lung injury from various pathogens, making IL-6 an important mediator in the host's susceptibility to respiratory infections. The cellular response to IL-6 is mediated through a Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signal transduction pathway. Human metapneumovirus (hMPV) is an important causative agent of viral respiratory infections known to inhibit the IFN-mediated activation of STAT1. However, little is known about the interactions between this virus and other STAT signalling cascades. Herein, we showed that hMPV can attenuate the IL-6-mediated JAK/STAT3 signalling cascade in lung epithelial cells. HMPV inhibited a key event in this pathway by impeding the phosphorylation and nuclear translocation of STAT3 in A549 cells and in primary normal human bronchial epithelial cells. Further studies established that hMPV interrupted the IL-6-induced JAK/STAT pathway early in the signal transduction pathway by blocking the phosphorylation of JAK2. By antagonizing the IL-6-mediated JAK/STAT3 pathway, hMPV perturbed the expression of IL-6-inducible genes important for apoptosis, cell differentiation and growth. Infection with hMPV also differentially regulated the effects of IL-6 on apoptosis. Thus, hMPV regulation of these genes could usurp the protective roles of IL-6, and these data provide insight into an important element of viral pathogenesis.

  16. Genomic regulation of invasion by STAT3 in triple negative breast cancer.

    PubMed

    McDaniel, Joy M; Varley, Katherine E; Gertz, Jason; Savic, Daniel S; Roberts, Brian S; Bailey, Sarah K; Shevde, Lalita A; Ramaker, Ryne C; Lasseigne, Brittany N; Kirby, Marie K; Newberry, Kimberly M; Partridge, E Christopher; Jones, Angela L; Boone, Braden; Levy, Shawn E; Oliver, Patsy G; Sexton, Katherine C; Grizzle, William E; Forero, Andres; Buchsbaum, Donald J; Cooper, Sara J; Myers, Richard M

    2017-01-31

    Breast cancer is a heterogeneous disease comprised of four molecular subtypes defined by whether the tumor-originating cells are luminal or basal epithelial cells. Breast cancers arising from the luminal mammary duct often express estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth receptor 2 (HER2). Tumors expressing ER and/or PR are treated with anti-hormonal therapies, while tumors overexpressing HER2 are targeted with monoclonal antibodies. Immunohistochemical detection of ER, PR, and HER2 receptors/proteins is a critical step in breast cancer diagnosis and guided treatment. Breast tumors that do not express these proteins are known as "triple negative breast cancer" (TNBC) and are typically basal-like. TNBCs are the most aggressive subtype, with the highest mortality rates and no targeted therapy, so there is a pressing need to identify important TNBC tumor regulators. The signal transducer and activator of transcription 3 (STAT3) transcription factor has been previously implicated as a constitutively active oncogene in TNBC. However, its direct regulatory gene targets and tumorigenic properties have not been well characterized. By integrating RNA-seq and ChIP-seq data from 2 TNBC tumors and 5 cell lines, we discovered novel gene signatures directly regulated by STAT3 that were enriched for processes involving inflammation, immunity, and invasion in TNBC. Functional analysis revealed that STAT3 has a key role regulating invasion and metastasis, a characteristic often associated with TNBC. Our findings suggest therapies targeting STAT3 may be important for preventing TNBC metastasis.

  17. LPA Induces Colon Cancer Cell Proliferation through a Cooperation between the ROCK and STAT-3 Pathways

    PubMed Central

    Leve, Fernanda; Peres-Moreira, Rubem J.; Binato, Renata; Abdelhay, Eliana; Morgado-Díaz, José A.

    2015-01-01

    Lysophosphatidic acid (LPA) plays a critical role in the proliferation and migration of colon cancer cells; however, the downstream signaling events underlying these processes remain poorly characterized. The aim of this study was to investigate the signaling pathways triggered by LPA to regulate the mechanisms involved in the progression of colorectal cancer (CRC). We have used three cell line models of CRC, and initially analyzed the expression profile of LPA receptors (LPAR). Then, we treated the cells with LPA and events related to their tumorigenic potential, such as migration, invasion, anchorage-independent growth, proliferation as well as apoptosis and cell cycle were evaluated. We used the Chip array technique to analyze the global gene expression profiling that occurs after LPA treatment, and we identified cell signaling pathways related to the cell cycle. The inhibition of these pathways verified the conclusions of the transcriptomic analysis. We found that the cell lines expressed LPAR1, -2 and -3 in a differential manner and that 10 μM LPA did not affect cell migration, invasion and anchorage-independent growth, but it did induce proliferation and cell cycle progression in HCT-116 cells. Although LPA in this concentration did not induce transcriptional activity of β-catenin, it promoted the activation of Rho and STAT-3. Moreover, ROCK and STAT-3 inhibitors prevented LPA-induced proliferation, but ROCK inhibition did not prevent STAT-3 activation. Finally, we observed that LPA regulates the expression of genes related to the cell cycle and that the combined inhibition of ROCK and STAT-3 prevented cell cycle progression and increased the LPA-induced expression of cyclins E1, A2 and B1 to a greater degree than either inhibitor alone. Overall, these results demonstrate that LPA increases the proliferative potential of colon adenocarcinoma HCT-116 cells through a mechanism involving cooperation between the Rho-ROCK and STAT3 pathways involved in cell

  18. LPA Induces Colon Cancer Cell Proliferation through a Cooperation between the ROCK and STAT-3 Pathways.

    PubMed

    Leve, Fernanda; Peres-Moreira, Rubem J; Binato, Renata; Abdelhay, Eliana; Morgado-Díaz, José A

    2015-01-01

    Lysophosphatidic acid (LPA) plays a critical role in the proliferation and migration of colon cancer cells; however, the downstream signaling events underlying these processes remain poorly characterized. The aim of this study was to investigate the signaling pathways triggered by LPA to regulate the mechanisms involved in the progression of colorectal cancer (CRC). We have used three cell line models of CRC, and initially analyzed the expression profile of LPA receptors (LPAR). Then, we treated the cells with LPA and events related to their tumorigenic potential, such as migration, invasion, anchorage-independent growth, proliferation as well as apoptosis and cell cycle were evaluated. We used the Chip array technique to analyze the global gene expression profiling that occurs after LPA treatment, and we identified cell signaling pathways related to the cell cycle. The inhibition of these pathways verified the conclusions of the transcriptomic analysis. We found that the cell lines expressed LPAR1, -2 and -3 in a differential manner and that 10 μM LPA did not affect cell migration, invasion and anchorage-independent growth, but it did induce proliferation and cell cycle progression in HCT-116 cells. Although LPA in this concentration did not induce transcriptional activity of β-catenin, it promoted the activation of Rho and STAT-3. Moreover, ROCK and STAT-3 inhibitors prevented LPA-induced proliferation, but ROCK inhibition did not prevent STAT-3 activation. Finally, we observed that LPA regulates the expression of genes related to the cell cycle and that the combined inhibition of ROCK and STAT-3 prevented cell cycle progression and increased the LPA-induced expression of cyclins E1, A2 and B1 to a greater degree than either inhibitor alone. Overall, these results demonstrate that LPA increases the proliferative potential of colon adenocarcinoma HCT-116 cells through a mechanism involving cooperation between the Rho-ROCK and STAT3 pathways involved in cell

  19. Procaine Attenuates Pain Behaviors of Neuropathic Pain Model Rats Possibly via Inhibiting JAK2/STAT3

    PubMed Central

    Li, Donghua; Yan, Yurong; Yu, Lingzhi; Duan, Yong

    2016-01-01

    Neuropathic pain (NPP) is the main culprit among chronic pains affecting the normal life of patients. Procaine is a frequently-used local anesthesia with multiple efficacies in various diseases. However, its role in modulating NPP has not been reported yet. This study aims at uncovering the role of procaine in NPP. Rats were pretreated with procaine by intrathecal injection. Then NPP rat model was induced by sciatic nerve chronic compression injury (CCI) and behavior tests were performed to analyze the pain behaviors upon mechanical, thermal and cold stimulations. Spinal expression of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) was detected by qRT-PCR and western blot. JAK2 was also overexpressed in procaine treated model rats for behavior tests. Results showed that procaine pretreatment improved the pain behaviors of model rats upon mechanical, thermal and cold stimulations, with the best effect occurring on the 15th day post model construction (p<0.05). Procaine also inhibited JAK2 and STAT3 expression in both mRNA (p<0.05) and protein levels. Overexpression of JAK2 increased STAT3 level and reversed the improvement effects of procaine in pain behaviors (p<0.01). These findings indicate that procaine is capable of attenuating NPP, suggesting procaine is a potential therapeutic strategy for treating NPP. Its role may be associated with the inhibition on JAK2/STAT3 signaling. PMID:27530113

  20. Insulin enhanced leptin-induced STAT3 signaling by inducing GRP78

    PubMed Central

    Thon, Mina; Hosoi, Toru; Ozawa, Koichiro

    2016-01-01

    Leptin, an adipocyte-derived hormone, centrally regulates energy homeostasis. Overlaps in the regulation of glucose and energy homeostasis have been reported between leptin and insulin. However, the effects of insulin on leptin’s actions in the central nervous system (CNS) have not yet been elucidated in detail. In the present study, we found that insulin potentiated leptin’s actions through GRP78 in the neuronal cell line, SH-SY5Y-ObRb. Since insulin induces GRP78, we speculated that it may also enhance leptin’s actions through this induction. We found that insulin enhanced leptin-induced STAT3 phosphorylation and this effect was ameliorated by the knockdown of GRP78. The role of GRP78 in leptin’s actions was also confirmed by impairments in leptin-induced STAT3 phosphorylation in HEK293-ObRb cells in which GRP78 was knocked down. Furthermore, we found that the overexpression of GRP78 enhanced leptin-induced STAT3 phosphorylation. These results suggest that GRP78 plays an important role in leptin’s actions. Furthermore, insulin may enhance the leptin-induced activation of STAT3 by inducing GRP78, which may provide an important connection between insulin and leptin in the CNS. PMID:27677243

  1. Lipopolysaccharides upregulate hepcidin in neuron via microglia and the IL-6/STAT3 signaling pathway.

    PubMed

    Qian, Zhong-Ming; He, Xuan; Liang, Tuo; Wu, Ka-Chun; Yan, Yik-Chun; Lu, Li-Na; Yang, Guang; Luo, Qian Qian; Yung, Wing-Ho; Ke, Ya

    2014-12-01

    Neuroinflammation is closely related to brain iron homeostasis. Our previous study demonstrated that lipopolysaccharides (LPS) can regulate expression of iron-regulatory peptide hepcidin; however, the mechanism is undefined. Here, we demonstrated that intracerebroventricular injection of LPS in rat brain upregulated hepcidin and downregulated ferroportin 1 in the cortex and substantia nigra. LPS increased hepcidin expression in neurons only when they were co-cultured with BV-2 microglia, and the upregulation was suppressed by IL-6 neutralizing antibody in vitro. In addition, IL-6 but not IL-1α, IL-1β, or tumor necrosis factor-alpha increased hepcidin expression and signal transducer and activator of transcription 3 (STAT3) phosphorylation in cortical neurons and MES23.5 dopaminergic neurons. These effects were blocked by the STAT3 inhibitor, stattic. Our results show that neurons are the major source of increased hepcidin expression in response to LPS challenge but microglia play a key mediator role by releasing IL-6 and recruiting the STAT3 pathway. We conclude that LPS upregulates hepcidin expression in neurons via microglia and the IL-6/STAT3 signaling pathway.

  2. Oncogenic role of rab escort protein 1 through EGFR and STAT3 pathway.

    PubMed

    Yun, Un-Jung; Sung, Jee Young; Park, Seog-Yun; Ye, Sang-Kyu; Shim, Jaegal; Lee, Jae-Seon; Hibi, Masahiko; Bae, Young-Ki; Kim, Yong-Nyun

    2017-02-23

    Rab escort protein-1 (REP1) is linked to choroideremia (CHM), an X-linked degenerative disorder caused by mutations of the gene encoding REP1 (CHM). REP1 mutant zebrafish showed excessive cell death throughout the body, including the eyes, indicating that REP1 is critical for cell survival, a hallmark of cancer. In the present study, we found that REP1 is overexpressed in human tumor tissues from cervical, lung, and colorectal cancer patients, whereas it is expressed at relatively low levels in the normal tissue counterparts. REP1 expression was also elevated in A549 lung cancer cells and HT-29 colon cancer cells compared with BEAS-2B normal lung and CCD-18Co normal colon epithelial cells, respectively. Interestingly, short interfering RNA (siRNA)-mediated REP1 knockdown-induced growth inhibition of cancer cell lines via downregulation of EGFR and inactivation of STAT3, but had a negligible effect on normal cell lines. Moreover, overexpression of REP1 in BEAS-2B cells enhanced cell growth and anchorage-independent colony formation with little increase in EGFR level and STAT3 activation. Furthermore, REP1 knockdown effectively reduced tumor growth in a mouse xenograft model via EGFR downregulation and STAT3 inactivation in vivo. These data suggest that REP1 plays an oncogenic role, driving tumorigenicity via EGFR and STAT3 signaling, and is a potential therapeutic target to control cancers.

  3. WP1066 Sensitizes Oral Squamous Cell Carcinoma Cells to Cisplatin by Targeting STAT3/miR-21 axis

    PubMed Central

    Zhou, Xuan; Ren, Yu; Liu, Aiqin; Jin, Rui; Jiang, Qingping; Huang, Yuanyuan; Kong, Lingping; Wang, Xudong; Zhang, Lun

    2014-01-01

    Accumulating evidence reveals that activation of STAT3 and miR-21 contributes to chemoresistance in multiple tumors. We examined the expression of STAT3 and miR-21 in 43 oral squamous cell carcinoma (OSCC) tumors and classified them into cisplatin sensitive or resistant group. Tca8113 and Tca8113/DDP cells were treated with cisplatin (DDP), WP1066 (STAT3 inhibitor) or in combination. MTT, colony formation, wound healing, 3-D culture, and transwell chamber assays were used to evaluate the malignant phenotype of OSCC cells. We evaluated the effect of WP1066 on the expression of STAT3 and miR-21. A Tca8113/DDP OSCC xenograft tumor model was established to evaluate the therapeutic effect of WP1066 in combination with DDP. The expression of STAT3/miR-21 was significantly increased in DDP-resistant OSCC samples and Tca8113/DDP cells compared to its parental cell. Treatment of DDP combined with WP1066 efficiently inhibited Tca8113 and Tca8113/DDP cell proliferation, migration and invasion. STAT3 mediated OSCC cell survival and DDP resistance through upregulating the expression of miR-21 and downregulating miR-21 downstream targets, including PTEN, TIMP3 and PDCD4. WP1066 plus DDP treatment could inhibit Tca8113 and Tca8113/DDP cell growth by inhibiting STAT3 phosphorylation and miR-21 expression. These results indicated that STAT3/miR-21 axis could be a candidate therapeutic target for OSCC chemoresistance. PMID:25514838

  4. Pancreatic stellate cell secreted IL-6 stimulates STAT3 dependent invasiveness of pancreatic intraepithelial neoplasia and cancer cells.

    PubMed

    Nagathihalli, Nagaraj S; Castellanos, Jason A; VanSaun, Michael N; Dai, Xizi; Ambrose, Mahogany; Guo, Qiaozhi; Xiong, Yanhua; Merchant, Nipun B

    2016-10-04

    Pancreatic ductal adenocarcinoma (PDAC) is a dynamic tumor supported by several stromal elements such as pancreatic stellate cells (PSC). Significant crosstalk exists between PSCs and tumor cells to stimulate oncogenic signaling and malignant progression of PDAC. However, how PSCs activate intercellular signaling in PDAC cells remains to be elucidated. We have previously shown that activated signal transducer and activator of transcription 3 (STAT3) signaling is a key component in the progression of pancreatic neoplasia. We hypothesize that PSC secreted IL-6 activates STAT3 signaling to promote PanIN progression to PDAC. Human PDAC and mouse PanIN cells were treated with PSC-conditioned media (PSC-CM), and phospho- and total-STAT3 levels by immunoblot analysis were determined. IL-6 was quantified in PSC-CM and cell invasion and colony formation assays were performed in the presence or absence of a neutralizing IL-6 antibody and the JAK/STAT3 inhibitor AZD1480. Serum from Ptf1aCre/+;LSL-KrasG12D/+;Tgfbr2flox/flox (PKT) and LSL-KrasG12D/+; Trp53R172H/+; Pdx1Cre/+ (KPC) mice demonstrated increased levels of IL-6 compared to serum from non-PDAC bearing KC and PK mice. PSC secreted IL-6 activated STAT3 signaling in noninvasive, precursor PanIN cells as well as PDAC cells, resulting in enhanced cell invasion and colony formation in both cell types. There was a significant positive linear correlation between IL-6 concentration and the ratio of phosphorylated STAT3/total STAT3. IL-6 neutralization or STAT3 inhibition attenuated PSC-CM induced activation of STAT3 signaling and tumorigenicity. These data provide evidence that PSCs are directly involved in promoting the progression of PanINs towards invasive carcinoma. This study demonstrates a novel role of PSC secreted IL-6 in transitioning noninvasive pancreatic precursor cells into invasive PDAC through the activation of STAT3 signaling.

  5. Pancreatic stellate cell secreted IL-6 stimulates STAT3 dependent invasiveness of pancreatic intraepithelial neoplasia and cancer cells

    PubMed Central

    Nagathihalli, Nagaraj S.; Castellanos, Jason A.; VanSaun, Michael N.; Dai, Xizi; Ambrose, Mahogany; Guo, Qiaozhi; Xiong, Yanhua; Merchant, Nipun B.

    2016-01-01

    Pancreatic ductal adenocarcinoma (PDAC) is a dynamic tumor supported by several stromal elements such as pancreatic stellate cells (PSC). Significant crosstalk exists between PSCs and tumor cells to stimulate oncogenic signaling and malignant progression of PDAC. However, how PSCs activate intercellular signaling in PDAC cells remains to be elucidated. We have previously shown that activated signal transducer and activator of transcription 3 (STAT3) signaling is a key component in the progression of pancreatic neoplasia. We hypothesize that PSC secreted IL-6 activates STAT3 signaling to promote PanIN progression to PDAC. Human PDAC and mouse PanIN cells were treated with PSC-conditioned media (PSC-CM), and phospho- and total-STAT3 levels by immunoblot analysis were determined. IL-6 was quantified in PSC-CM and cell invasion and colony formation assays were performed in the presence or absence of a neutralizing IL-6 antibody and the JAK/STAT3 inhibitor AZD1480. Serum from Ptf1aCre/+;LSL-KrasG12D/+;Tgfbr2flox/flox' (PKT) and LSL-KrasG12D/+; Trp53R172H/+; Pdx1Cre/+ (KPC) mice demonstrated increased levels of IL-6 compared to serum from non-PDAC bearing KC and PK mice. PSC secreted IL-6 activated STAT3 signaling in noninvasive, precursor PanIN cells as well as PDAC cells, resulting in enhanced cell invasion and colony formation in both cell types. There was a significant positive linear correlation between IL-6 concentration and the ratio of phosphorylated STAT3/total STAT3. IL-6 neutralization or STAT3 inhibition attenuated PSC-CM induced activation of STAT3 signaling and tumorigenicity. These data provide evidence that PSCs are directly involved in promoting the progression of PanINs towards invasive carcinoma. This study demonstrates a novel role of PSC secreted IL-6 in transitioning noninvasive pancreatic precursor cells into invasive PDAC through the activation of STAT3 signaling. PMID:27602757

  6. STAT3 governs hyporesponsiveness and granzyme B-dependent suppressive capacity in human CD4+ T cells

    PubMed Central

    Schmetterer, Klaus G.; Neunkirchner, Alina; Wojta-Stremayr, Daniela; Leitner, Judith; Steinberger, Peter; Pickl, Winfried F.

    2015-01-01

    Signal transducer and activator of transcription 3 (STAT3) integrates key signals of cell surface immune receptors, yet its precise role in cluster of differentiation (CD)4+ T cells is not well-established. Current research has indicated T-helper cell 17–inducing roles but also tolerogenic roles. To address this issue, human T cells were transduced with the constitutively active STAT3 mutant STAT3C. Following stimulation, STAT3C+ T cells up-regulated IL-10 (4.1 ± 0.5-fold; P < 0.001) and granzyme B (2.5 ± 1.2, P < 0.05) secretion, combined with significantly reduced IFN-γ (35 ± 5%), IL-2 (57 ± 4%), TNF-α (64 ± 8%), and IL-13 (89 ± 3%) secretion (P < 0.001). CD3/CD2- or CD3/CD28-activated STAT3C+ T cells revealed reduced proliferation (53.4 ± 23.5% and 70.5 ± 10.4%, respectively), which was independent of IL-10 production and significantly suppressed effector T cell proliferation by 68.7 ± 10.6% and 65.9 ± 2.6%, respectively (P < 0.001). Phenotypically, STAT3C-transgenic CD4+ T cells resembled effector T cells regarding expression of T regulatory cell markers, but up-regulated granzyme B expression levels by 2.4-fold (P < 0.05). Suppression was cell contact dependent and mediated by granzyme B-induced cell death, but was independent of IL-10 and TGF-β. Notably, peripheral blood CD4+CD45RA−lymphocyte activation gene-3+CD49+ type 1 regulatory T cells revealed activation-induced hyperphosphorylation of STAT3. In agreement, pharmacological inhibition of STAT3 activation partially reverted hyporesponsiveness of peripheral type 1 regulatory T cells (increasing their division index from 0.46 ± 0.11 to 0.89 ± 0.04; P < 0.01). These observations indicate a clear-cut relation between activation of STAT3 and the acquisition of a tolerogenic program, which is also used by peripheral blood type 1 regulatory T cells.—Schmetterer, K. G., Neunkirchner, A., Wojta-Stremayr, D., Leitner, J., Steinberger, P., Pickl, W. F. STAT3 governs hyporesponsiveness and

  7. 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-κB (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-α, but not by Il-6/gp130. This Rantes production was dependent on the binding of a p65/Stat3 complex to NF-κB–binding sites within the Rantes promoter, with shRNA knockdown of either Stat3 or p65 markedly attenuating Rantes production. In vivo, acute NF-κB 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

  8. Angiotensin-(1-7) has a dual role on growth-promoting signalling pathways in rat heart in vivo by stimulating STAT3 and STAT5a/b phosphorylation and inhibiting angiotensin II-stimulated ERK1/2 and Rho kinase activity.

    PubMed

    Giani, Jorge F; Gironacci, Mariela M; Muñoz, Marina C; Turyn, Daniel; Dominici, Fernando P

    2008-05-01

    Angiotensin (ANG) II contributes to cardiac remodelling by inducing the activation of several signalling molecules, including ERK1/2, Rho kinase and members of the STAT family of proteins. Angiotensin-(1-7) is produced in the heart and inhibits the proliferative actions of ANG II, although the mechanisms of this inhibition are poorly understood. Accordingly, in the present study we examined whether ANG-(1-7) affects the ANG II-mediated activation of ERK1/2 and Rho kinase, STAT3 and STAT5a/b in rat heart in vivo. We hypothesized that ANG-(1-7) inhibits these growth-promoting pathways, counterbalancing the trophic action of ANG II. Solutions of normal saline (0.9% NaCl) containing ANG II (8 pmol kg(-1)) plus ANG-(1-7) in increasing doses (from 0.08 to 800 pmol kg(-1)) were administered via the inferior vena cava to anaesthetized male Sprague-Dawley rats. After 5 min, hearts were removed and ERK1/2, Rho kinase, STAT3 and STAT5a/b phosphorylation was determined by Western blotting using phosphospecific antibodies. Angiotensin II stimulated ERK1/2 and Rho kinase phosphorylation (2.3 +/- 0.2- and 2.1 +/- 0.2-fold increase over basal values, respectively), while ANG-(1-7) was without effect. The ANG II-mediated phosphorylation of ERK1/2 and Rho kinase was prevented in a dose-dependent manner by ANG-(1-7) and disappeared in the presence of the Mas receptor antagonist d-Ala7-ANG-(1-7). Both ANG II and ANG-(1-7) increased STAT3 and STAT5a/b phosphorylation to a similar extent (130-140% increase). The ANG-(1-7)-stimulated STAT phosphorylation was blocked by the AT(1) receptor antagonist losartan and not by d-Ala7-ANG-(1-7). Our results show a dual action of ANG-(1-7), that is, a stimulatory effect on STAT3 and 5a/b phosphorylation through AT(1) receptors and a blocking action on ANG II-stimulated ERK1/2 and Rho kinase phosphorylation through Mas receptor activation. The latter effect could be representative of a mechanism for a protective role of ANG-(1-7) in the heart by

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

    SciTech Connect

    Chetty, Chandramu; Dontula, Ranadheer; Gujrati, Meena; Lakka, Sajani S.

    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. T