ag-490 and Glioma

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

The compound WP1066 was originally synthesized by modifying the structure of AG490, which inhibits the activation of signal transducer and activator of transcription 3 (STAT3) by directly targeting Janus kinases (JAKs). WP1066 exhibits stronger anti-cancer activity than AG490 against malignant glioma and other cancer cells and is regarded as a promising therapeutic agent. By screening a small library of target-known compounds, we identified WP1066 as an inhibitor of macrophage cell death induced by agonists of the NLRP3 inflammasome, an intracellular protein complex required for the processing of the proinflammatory cytokine interleukin (IL)-1β. WP1066 strongly inhibited cell death as well as extracellular release of IL-1β induced by inflammasome agonists in mouse peritoneal exudate cells and human leukemia monocytic THP-1 cells that were differentiated into macrophagic cells by treatment with PMA. However, inflammasome agonists did not increase STAT3 phosphorylation, and another JAK inhibitor, ruxolitinib, did not inhibit cell death, although it strongly inhibited basal STAT3 phosphorylation. Thus, WP1066 appears to suppress macrophage cell death independently of its inhibitory effect on STAT3. In contrast, WP1066 itself induced the death of undifferentiated THP-1 cells, suggesting that WP1066 differentially modulates cell death in a context-dependent manner. Consistent with previous findings, WP1066 induced the death of human glioma A172 and T98G cells. However, neither ruxolitinib nor AG490, the former of which completely suppressed STAT3 phosphorylation, induced the death of these glioma cells. These results suggest that WP1066 targets cell death-modulating molecules other than those involved in JAK-STAT3 signaling.

Topics: Animals; Antineoplastic Agents; Cell Death; Cell Line, Tumor; Cell Proliferation; Glioma; Humans; Inflammasomes; Interleukin-1beta; Janus Kinases; Macrophages; Mice; Nitriles; Phosphorylation; Pyrazoles; Pyridines; Pyrimidines; 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 formulation of quercetin nanoliposomes (QUE-NLs) has been shown to enhance QUE antitumor activity in C6 glioma cells. At high concentrations, QUE-NLs induce necrotic cell death. In this study, we probed the molecular mechanisms of QUE-NL-induced C6 glioma cell death and examined whether QUE-NL-induced programmed cell death involved Bcl-2 family and mitochondrial pathway through STAT3 signal transduction pathway. Downregulation of Bcl-2 and the overexpression of Bax by QUE-NL supported the involvement of Bcl-2 family proteins upstream of C6 glioma cell death. In addition, the activation of JAK2 and STAT3 were altered following exposure to QUE-NLs in C6 glioma cells, suggesting that QUE-NLs downregulated Bcl-2 mRNAs expression and enhanced the expression of mitochondrial mRNAs through STAT3-mediated signaling pathways either via direct or indirect mechanisms. There are several components such as ROS, mitochondrial, and Bcl-2 family shared by the necrotic and apoptotic pathways. Our studies indicate that the signaling cross point of the mitochondrial pathway and the JAK2/STAT3 signaling pathway in C6 glioma cell death is modulated by QUE-NLs. In conclusion, regulation of JAK2/STAT3 and ROS-mediated mitochondrial pathway agonists alone or in combination with treatment by QUE-NLs could be a more effective method of treating chemical-resistant glioma.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Shape; Cell Survival; Drug Screening Assays, Antitumor; Glioma; Humans; Janus Kinase 2; L-Lactate Dehydrogenase; Liposomes; Mitochondria; Nanocapsules; Necrosis; Particle Size; Quercetin; Reactive Oxygen Species; Signal Transduction; STAT3 Transcription Factor; Tumor Suppressor Protein p53; Tyrphostins

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.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cluster Analysis; Focal Adhesion Protein-Tyrosine Kinases; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Glioma; Humans; Janus Kinases; Mitogen-Activated Protein Kinases; Phosphorylation; Rats; Signal Transduction; STAT3 Transcription Factor; Tyrphostins

Signal transducer and activator of transcription-3 (STAT3) is constitutively activated in a variety of cancer types, including malignant gliomas. STAT3 is activated by phosphorylation of a tyrosine residue, after which it dimerizes and translocates into the nucleus. There it regulates the expression of several genes responsible for proliferation and survival at the transcriptional level. A selective inhibitor of STAT3 phosphorylation, AG490, has been shown to inhibit growth and induce apoptosis in some cancer cell types. However, although AG490 routinely shows in vitro anticancer activity, it has not consistently demonstrated an in vivo anticancer effect in animal models. Here, we have tested WP1066, a novel inhibitor structurally related to AG490 but significantly more potent and active, against human malignant glioma U87-MG and U373-MG cells in vitro and in vivo. IC(50) values for WP1066 were 5.6 muM in U87-MG cells and 3.7 muM in U373-MG cells, which represents 18-fold and eightfold increases in potency, respectively, over that of AG490. WP1066 activated Bax, suppressed the expression of c-myc, Bcl-X(L) and Mcl-1, and induced apoptosis. Systemic intraperitoneal administration of WP1066 in mice significantly (P<0.001) inhibited the growth of subcutaneous malignant glioma xenografts during the 30-day follow-up period. Immunohistochemical analysis of the excised tumors revealed that phosphorylated STAT3 levels in the WP1066 treatment group remained inhibited at 3 weeks after the final WP1066 injection, whereas tumors from the control group expressed high levels of phosphorylated STAT3. We conclude that WP1066 holds promise as a therapeutic agent against malignant gliomas.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Survival; Glioma; Humans; Pyridines; Signal Transduction; STAT3 Transcription Factor; Tyrphostins

We determined the cytotoxicity of AG490 as a single agent and in combination with 7-hydroxystaurosporine (UCN-01) in a panel of malignant human glioma cell lines. Because p53 has important roles in cell cycle checkpoints, it has been anticipated that modulation of checkpoint pathways should sensitize p53 defective cells while sparing the normal cells. Cell proliferation was determined from dose-response curves. AG490 was effective as a cytotoxic agent alone regardless of p53 status. Combining the Chk1 inhibitor UCN-01 dramatically enhanced the response to AG490 in p53-mutated or deleted glioma cells. An opposite effect was noted in p53-wild type cells, in which UCN-01 and AG490 had antagonistic effects on cell proliferation and viability. We found that AG490 enhanced BAD phosphorylation in p53 wild type glioma cells, which appeared to protect against UCN-01-induced cytotoxicity, whereas AG490 enhanced UCN-01-induced cytotoxicity in p53 defective cell lines by suppression of BAD phosphorylation and induction of BAX and PARP cleavage. These observations highlight the potential for genotype-dependent factors to strongly influence response to signaling-targeted therapies in malignant gliomas and the importance of considering such factors in correlative response analyses for these agents.

Topics: Annexin A5; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; bcl-2-Associated X Protein; bcl-Associated Death Protein; Cell Line, Tumor; Dose-Response Relationship, Drug; Drug Synergism; Genes, p53; Glioma; Humans; Poly(ADP-ribose) Polymerases; Signal Transduction; Staurosporine; Tumor Suppressor Protein p53; Tyrphostins

Recent studies suggest that erythropoietin plays an important role in the process of neoplastic transformation and malignant phenotype progression observed in malignancy. To study the role of erythropoietin and its receptor (EPOR) on the response of cancer cells in vitro, we used two solid tumor cell lines, namely the human malignant glioma cell line U87 and the primary cervical cancer cell line HT100. All experiments were done with heat-inactivated fetal bovine serum in order to inactivate any endogenous bovine erythropoietin. The expression of the EPOR in these cells was confirmed with immunoblot techniques. The addition of exogenous recombinant human erythropoietin (rhEPO) induces the cancer cells to become more resistant to ionizing radiation and to cisplatin. Furthermore, this rhEPO-induced resistance to ionizing radiation and to cisplatin was reversed by the addition of tyrphostin (AG490), an inhibitor of JAK2. Our findings indicate that rhEPO result in a significant, JAK2-dependent, in vitro resistance to ionizing radiation and to cisplatin in the human cancer cells lines studied in this report.

Topics: Animals; Antineoplastic Agents; Cattle; Cisplatin; Drug Resistance, Neoplasm; Erythropoietin; Female; Glioma; Humans; Janus Kinase 2; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Radiation Tolerance; Radiation, Ionizing; Receptors, Erythropoietin; Recombinant Proteins; Tumor Cells, Cultured; Tyrphostins; Uterine Cervical Neoplasms