ag-490 and Brain-Neoplasms

Epithelial-to-mesenchymal transition (EMT) recapitulates metastasis and can be induced in vitro through transforming growth factor (TGF)-β signaling. A role for MMP activity in glioblastoma multiforme has been ascribed to EMT, but the molecular crosstalk between TGF-β signaling and membrane type 1 MMP (MT1-MMP) remains poorly understood. Here, the expression of common EMT biomarkers, induced through TGF-β and the MT1-MMP inducer concanavalin A (ConA), was explored using RNA-seq analysis and differential gene arrays in human U87 glioblastoma cells. TGF-β triggered SNAIL and fibronectin expressions in 2D-adherent and 3D-spheroid U87 glioblastoma cell models. Those inductions were antagonized by the TGF-β receptor kinase inhibitor galunisertib, the JAK/STAT inhibitors AG490 and tofacitinib, and by the diet-derived epigallocatechin gallate (EGCG). Transient gene silencing of MT1-MMP prevented the induction of SNAIL by ConA and abrogated TGF-β-induced cell chemotaxis. Moreover, ConA induced STAT3 and Src phosphorylation, suggesting these pathways to be involved in the MT1-MMP-mediated signaling axis that led to SNAIL induction. Our findings highlight a new signaling axis linking MT1-MMP to TGF-β-mediated EMT-like induction in glioblastoma cells, the process of which can be prevented by the diet-derived EGCG.

Topics: Brain Neoplasms; Catechin; Cell Line, Tumor; Concanavalin A; Epithelial-Mesenchymal Transition; Fibronectins; Glioblastoma; Humans; Matrix Metalloproteinase 14; Piperidines; Pyrazoles; Pyrimidines; Quinolines; Receptors, Transforming Growth Factor beta; Signal Transduction; Snail Family Transcription Factors; STAT3 Transcription Factor; Transforming Growth Factor beta1; Tyrphostins

Glioma is the most aggressive primary brain tumor. We have previously provided evidence that IFITM3 promoted glioma cells migration. However, the mechanism of how IFITM3 regulates glioma cells invasion and whether IFITM3 participates in TGF-β-mediated glioma invasion are still unknown. In this paper, we proved that IFITM3 was notably up-regulated in glioma tissues. Knockdown of IFITM3 suppressed STAT3 phosphorylation in vitro, and a specific STAT3 inhibitor AG490 reversed IFITM3-induced invasion of glioma cells. Furthermore, IFITM3 expression was induced by TGF-β in glioma and IFITM3 knockdown abolished TGF-β-mediated glioma cells invasion. Collectively, the results indicate that IFITM3/STAT3 axis may promote TGF-β-induced glioma cells invasion. This study provided some suggestions for the clinical treatment of the brain tumor.

Topics: Adult; Brain Neoplasms; Cell Line, Tumor; Cell Movement; Cell Proliferation; Female; Gene Expression Regulation, Neoplastic; Glioma; Humans; Male; Membrane Proteins; Middle Aged; Phosphorylation; RNA-Binding Proteins; STAT3 Transcription Factor; Transcriptional Activation; Transforming Growth Factor beta; Tyrphostins

As a commonly mutated form of the epidermal growth factor receptor, EGFRvIII strongly promotes glioblastoma (GBM) tumor invasion and progression, but the mechanisms underlying this promotion are not fully understood.. Through gene manipulation, we established EGFRvIII-, wild-type EGFR-, and vector-expressing GBM cells. We used cDNA microarrays, bioinformatics analysis, target-blocking migration and invasion assays, Western blotting, and an orthotopic U87MG GBM model to examine the phenotypic shifts and treatment effects of EGFRvIII expression in vitro and in vivo. Confocal imaging, co-immunoprecipitation, and siRNA assays detected the focal adhesion-associated complex and their relationships to the EGFRvIII/JAK2/STAT3 axis in GBM cells.. The activation of JAK2/STAT3 signaling is vital for promoting migration and invasion in EGFRvIII-GBM cells. AG490 or WP1066, the JAK2/STAT3 inhibitors, specifically destroyed EGFRvIII/JAK2/STAT3-related focal adhesions and depleted the activation of EGFR/Akt/FAK and JAK2/STAT3 signaling, thereby abolishing the ability of EGFRvIII-expressing GBM cells to migrate and invade. Furthermore, the RNAi silencing of JAK2 in EGFRvIII-expressing GBM cells significantly attenuated their ability to migrate and invade; however, as a result of a potential EGFRvIII-JAK2-STAT3 activation loop, neither EGFR nor STAT3 knockdown yielded the same effects. Moreover, AG490 or JAK2 gene knockdown greatly suppressed tumor invasion and progression in the U87MG-EGFRvIII orthotopic models.. Taken together, our data demonstrate that JAK2/STAT3 signaling is essential for EGFRvIII-driven migration and invasion by promoting focal adhesion and stabilizing the EGFRvIII/JAK2/STAT3 axis. Targeting JAK2/STAT3 therapy, such as AG490, may have potential clinical implications for the tailored treatment of GBM patients bearing EGFRvIII-positive tumors.

Topics: Animals; Antineoplastic Agents; Brain Neoplasms; Cell Line, Tumor; Enzyme Inhibitors; ErbB Receptors; Focal Adhesions; Glioblastoma; Humans; Janus Kinase 2; Mice; Mice, Nude; Neoplasm Invasiveness; Signal Transduction; STAT3 Transcription Factor; Tyrphostins

To study the relationship of basic fibroblast growth factor (bFGF) and signal transducer and activator of transcription 3(STAT3) in glioma apoptosis and possible mechanisms of its interaction.. Two glioblastomamultiforme (GBM) cell lines: U87 (wild-type p53) and U251 (mutant p53) were used in this study and divided into normal control group, mock group and experiment group.Small interfering RNA-carried recombinant lentivirus, LV-bFGFsiRNA and LV-STAT3siRNA, targeting bFGF and STAT3 were constructed respectively. After 48 hours of lentivirus transfection, small molecular inhibitors were used to block specific signaling pathways, AG490 20 µmol/L blocking JAK, LY294002 20 µmol/L blocking PI3K/Akt pathways for 24 hours, 48 hours and 72 hours, respectively. Then, apoptosis, changes in apoptosis-related proteins and mitochondrial membrane potential were detected through the methods of flow cytometry, protein chip and confocal microscopy, respectively.Groups were compared using single factor analysis of variance (One-way ANOVA).. Western blot results revealed the levels of Tyr705 and Ser727 phosphorylationin reduced in a time dependent manner by blocking JAK and PI3K/Akt pathway respectively. The results of flow cytometry showed that the apoptosis rate in normal control group, mock group, experiment group were 17.97% ± 0.24%, 18.26% ± 0.88%, 46.57% ± 1.63% in U87 cells and 15.94% ± 1.18%, 16.88% ± 0.17%, 39.34% ± 0.87% in U251 cells, respectively. There was no statistically significant change between the normal control group and the mock group (P > 0.05) , while when compared with the experiment group, both group showed statistically significant difference (F = 697.41, 729.58, both P < 0.05). The results of protein chip demonstrated that protein expression of Bad, Caspase3, Cytochrome C, p27 were higher and XIAP was lower in the experiment group compared with the normal control group and mock group. Also, confocal microscopy could detect apoptosis and mitochondrial membrane potential reduced significantly in the experimental group compared with the normal control group and the mock group.. bFGF mainly interacts with STAT3 tyrosine site-pSTAT3(Tyr705) to influence the level of STAT3 phosphorylation;blocking bFGF/STAT3 signaling pathway can induce glioma cell apoptosis through mitochondrial pathway.

Topics: Apoptosis; Brain Neoplasms; Cell Line, Tumor; Cytochromes c; Fibroblast Growth Factor 2; Glioma; Humans; Mitochondria; Phosphatidylinositol 3-Kinases; Phosphorylation; RNA, Small Interfering; Signal Transduction; STAT3 Transcription Factor; Transfection; Tyrphostins

The objective of current treatment strategies for glioblastoma (GBM) is cytoreduction. Unfortunately, the deleterious migratory and invasive behavior of glial tumors remains largely unattended. The transcription factor signal transducer and activator of transcription (STAT) 3 is known to be involved in the development and progression of many different tumor types, including malignant gliomas. Beside other biological effects, STAT3 controls cell proliferation and tissue remodeling, processes common to both wound healing and tumor dissemination. Here, we report on impeded migratory and invasive potential of five different glioblastoma cell lines after treatment with AG490, a pharmacological inhibitor of the upstream STAT3 activator Janus kinase (JAK) 2. STAT3 was constitutively activated in all the cell lines tested, and treatment with AG490 eliminated the biologically active, tyrosine705-phosphorylated form of STAT3 in a dose-dependent fashion, as determined by Western blot analysis. Inhibition of activated STAT3 was paralleled by a decrease in transcriptional expression of the STAT3 target genes MMP-2 and MMP-9, and led to reduced proteolytic activity, as determined by zymography. Accordingly, the migratory behavior of all five GBM cell lines was impeded in monolayer wound-healing assays; invasive capacity in matrigel-coated trans-well assays was also hampered by treatment with AG490. The proliferative activity of the cell lines was also significantly reduced after treatment with AG490. The effects elicited by STAT3 inhibition were observed in both PTEN-expressing and PTEN-deficient cells. Because pharmacological inhibition of the JAK-2/STAT3 signaling pathway affects not only tumor cell proliferation but also the characteristic features of malignant gliomas, i.e. migration and invasion pertinent to invariable tumor recurrence and high morbidity, our findings support the idea that STAT3 is a suitable target in the treatment of brain tumors.

Topics: Apoptosis; Blotting, Western; Brain Neoplasms; Cell Adhesion; Cell Movement; Cell Proliferation; Cells, Cultured; Endothelium, Vascular; Enzyme Inhibitors; Glioblastoma; Humans; Janus Kinase 2; Matrix Metalloproteinase 2; Neoplasm Invasiveness; Phosphorylation; PTEN Phosphohydrolase; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; STAT3 Transcription Factor; Tyrphostins; Umbilical Veins; Wound Healing

Disruption of apoptosis may allow metastatic cell survival and confer resistance to chemotherapeutic drugs. We have analysed the molecular pathways that activate these survival genes in specific sites of metastasis. Estrogen receptor-negative breast cancer cell line MDA-MB435 and two metastatic sublines derived from lung (435L) and brain (435B) were analysed for the expression of members of the Bcl-2 family of apoptosis regulators. The levels of Bcl-2 were higher in the metastatic sublines than in parental cells, which correlated with the activation of Stat3, but not with the expression and/or activation of known bcl-2 transcription factors (CREB and WT1). In the brain subline, both expression of Bcl-2 and Stat3 activation were induced by epidermal growth factor and abrogated after treatment with kinase inhibitors specific for epidermal growth factor receptor or Jak2. Furthermore, transfection of 435B with a dominant-negative Stat3 markedly reduced the expression of Bcl-2 protein, whereas transient expression of a constitutively active Stat3 increased Bcl-2 in parental 435 cells. In addition, blockade of Stat3 activation by treatment with epidermal growth factor receptor and Jak2 kinase inhibitors or transfection with a dominant negative Stat3, sensitizes 435B cells to chemotherapy-induced apoptosis. Our data suggest that an increased activation of the Stat3-Bcl-2 pathway in estrogen receptor-negative metastatic breast cancer cell lines confer a survival advantage to these cells and contribute to their chemoresistance.

Topics: Antineoplastic Agents; Apoptosis; bcl-X Protein; Brain Neoplasms; Breast Neoplasms; Carcinoma; Cyclic AMP Response Element-Binding Protein; DNA-Binding Proteins; Enzyme Inhibitors; ErbB Receptors; Female; Humans; Janus Kinase 2; Lung Neoplasms; Neoplasm Metastasis; Neoplasms, Hormone-Dependent; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Receptors, Estrogen; STAT3 Transcription Factor; Trans-Activators; Transcription, Genetic; Tumor Cells, Cultured; Tyrphostins

Glioblastoma multiforme (GBM), the most common and malignant central nervous system tumor in humans, is highly proliferative and resistant to apoptosis. Stat3, a latent transcription factor being activated by aberrant cytokine or growth factor signaling, acts as a suppressor of apoptosis in a number of cancer cells. Here we report that GBM tumors and cell lines contain high levels of constitutively activated Stat3 when compared with normal human astrocytes, white matter, and normal tissue adjacent to tumor. The persistent activation of Stat3 is in part, attributable to an autocrine action of interleukin-6 in the GBM cell line U251. Janus kinase inhibitor AG490 inhibits Stat3 activation with a concomitant reduction in steady-state levels of Bcl-X(L), Bcl-2 and Mcl-1 proteins and induces apoptosis in U251 cells as revealed by Poly (ADP-ribose) polymerase cleavage and Annexin-V staining. Expression of a dominant negative mutant Stat3 protein or treatment with AG490 markedly reduces the proliferation of U251 cells by inhibiting the constitutive activation of Stat3. These results provide evidence that constitutive activation of Stat3 contributes to the pathogenesis of glioblastoma by promoting both proliferation and survival of GBM cells. Therefore, targeting Stat3 signaling may provide a potential therapeutic intervention for GBM.

Topics: Acute-Phase Proteins; Antineoplastic Agents; Apoptosis; Brain Neoplasms; Cell Division; Cell Survival; DNA-Binding Proteins; Enzyme Inhibitors; Glioblastoma; Humans; STAT3 Transcription Factor; Trans-Activators; Transcription, Genetic; Tumor Cells, Cultured; Tyrphostins