Notch1 promotes glioma cell migration and invasion by stimulating β-catenin and NF-κB signaling via AKT activation

The Notch signaling pathway has been implicated in both developmental processes and tumorigenesis. Aberrant Notch signaling has been repeatedly demonstrated to facilitate the proliferation and survival of glioma cells by regulating downstream effectors or other signaling pathways. In glioblastoma multiforme specimens from 59 patients, Notch1 was highly expressed in tumor tissues compared with normal brain tissues, and this expression was correlated with elevated AKT phosphorylation and Snail expression. Increased nuclear localization of β-catenin and p50 as well as enhanced IKKα/AKT interaction were also observed in glioma tissues. In U87MG cells, the activation of Notch1 by DLL4 stimulation or by the overexpression of Notch intracellular domain (NICD) resulted in AKT activation and thereby promoted β-catenin activity and NF-κB signaling. Inhibition of EGFR partially blocked the β-catenin and NF-κB signaling stimulated by Notch1 activation. Furthermore, NICD overexpression in U87MG cells led to the upregulated expression of several metastasis-associated molecules, which could be abrogated by the knockdown of either β-catenin or p50. In U87MG and U251 cells, DLL4-induced cellular migration and invasion could be inhibited by either β-catenin or a p50 inhibitor. Collectively, these results indicate that Notch activation could stimulate β-catenin and NF-κB signaling through AKT activation in glioma cells. Thus, Notch activation-stimulated β-catenin and NF-κB signaling synergistically promote the migratory and invasive properties of glioma cells.     

Scorpion venom induces glioma cell apoptosis in vivo and inhibits glioma tumor growth in vitro

Malignant gliomas are the main brain tumors notoriously resistant to currently available therapies, since they fail to undergo apoptosis upon antieaneer treatment. Recent progress on enhanced studies of ion channels involved in glioma cells shed new light on the investigation of glioma cell growth and proliferation. Here we report BmK scorpion venom.     

Silencing of IKKε using siRNA inhibits proliferation and invasion of glioma cells in vitro and in vivo

Recent studies implicated IKKε in the pathogenesis of many human cancers by promoting cell proliferation, increasing tumor angiogenesis and metastasis, and generating resistance to cell apoptosis. However, whether IKKε can influence the invasive ability and proliferation of glioma cells remains largely unknown. In this study, we showed that overexpression of IKKε is positively correlated to glioma pathological grade, suggesting that IKKε plays a role in tumor progression, rather than tumor initiation. Targeted knockdown of IKKε in human glioma cells using siRNA, was associated with inhibition of cell growth, cell cycle arrest and decreased cell invasion; however, notable apoptosis was not observed. Furthermore, we demonstrated that transposition of NF-κB p65 resulted in the alteration of these phenotypes. Tumor growth was attenuated in established subcutaneous gliomas in nude mice treated with IKKε siRNA in vivo. Collectively, our results suggest that deregulation of IKKε plays a pivotal role in the uncontrolled proliferation and malignant invasion of glioma cells in vitro and in vivo by targeting NF-κB. Silencing of IKKε using synthetic siRNAs may offer a novel therapeutic strategy for the treatment of glioma.     

Control of Atm−/− thymic lymphoma cell proliferation in vitro and in vivo by dexamethasone

Aim Ataxia telangiectasia (A-T) is an autosomal recessive disease in humans caused by mutations in the Atm (A-T mutated) gene. The disease involves multiple organ systems, and is associated with a high incidence of leukemias and lymphomas that develop in childhood. We have reported previously that thymic lymphoma development in Atm knockout (Atm–/–) mice is associated with elevated spontaneous DNA synthesis in thymocytes, and that dexamethasone (Dex) attenuates the elevated DNA synthesis and prevents thymic lymphoma development. The primary objectives of the present study were (1) to investigate possible mechanisms underlying the tumor-suppressing effect of Dex on Atm–/– thymic lymphoma cells, and (2) to determine whether Dex is an effective tumor-suppressing treatment in mice bearing transplanted Atm–/– thymic tumors.Methods Establishment of a number of Atm–/– thymic lymphoma (ATL) cell lines from Atm–/– mice, cell proliferation assays, cell cycle analyses, Western blotting and Hoechst nuclear staining were used to analyze the effects of Dex on Atm–/– thymic lymphoma cells. Atm–/– tumor cells were transplanted into the right flanks of Atm+/+ mice prior to the initiation of Dex treatment.Results Atm–/– tumor cells were highly sensitive to Dex, both in culture and in vivo as ectopic tumors in mice. In cultured ATL-1 cells, Dex induced apoptosis, arrested the cell cycle at the G₁ phase and downregulated NF-B and multiple cell cycle regulators, while upregulating the NF-B inhibitor IB. In Atm+/+ mice transplanted subcutaneously with ATL-1 cells, tumor growth was either prevented completely or significantly suppressed by Dex treatment.Conclusions Our findings identify potential mechanisms by which Dex affects the proliferation and survival of ATL-1 cells in culture, and provide evidence that Dex can suppress the proliferation of Atm–/– thymic lymphoma cells growing in the body. Together these results add to our earlier published data suggesting that the cellular pathways regulated by Dex may be promising therapeutic targets for prevention and treatment of thymic lymphomas in A-T individuals.     

A combination of methotrexate and irradiation promotes cell death in NK/T-cell lymphoma cells via down-regulation of NF-κB signaling

Nasal NK/T-cell lymphoma (NKTL) is a highly aggressive disease. Although radiotherapy is the first-line of treatment for NKTL, the clinical outcome is poor. Thus, there is a need for an effective radiosensitizer to improve the survival rate of patients. NF-κB activation contributes to cell survival as well as chemo- and radio-resistance in various cancer cells. In NKTL, the constitutive activation of NF-κB is also a critical factor. In the present study, we used two EBV-expressing NKTL cell lines (Hank-1 and NK-92) to evaluate the radiosensitizing effect of methotrexate (MTX), highlighting the role of NF-κB. Combined treatment of MTX and IR significantly induced apoptosis and growth inhibition in both NKTL cells. The synergistic cytotoxicity was correlated with blocking nuclear NF-κB and suppressing expression of NF-κB-mediated anti-apoptotic proteins. These data suggest that the combined treatment with MTX and IR can inhibit IR-induced NF-κB activation in NKTL cells. Taken together, co-treatment with MTX and IR may provide a therapeutic advantage for patients with NKTL.     

CARMA3 overexpression accelerates cell proliferation and inhibits paclitaxel-induced apoptosis through NF-κB regulation in breast cancer cells

CARMA3 was recently reported to be overexpressed in several cancers and associated with malignant behavior of cancer cells. However, the expression pattern and biological roles of CARMA3 in breast cancer have not been reported. In the present study, we found that CARMA3 was overexpressed in 41.9 % of breast cancer specimens. Significant association was observed between CARMA3 overexpression and TNM stage (p?=?0.0223), tumor size (p?=?0.0227), and ErbB-2 status (p?=?0.0049). Furthermore, knockdown of CARMA3 expression in MDA-MB-435 cells with high endogenous expression decreased cell proliferation and sensitized cell to paclitaxel-induced apoptosis, while overexpression of CARMA3 in MDA-MB-231 cell line promoted cell proliferation and inhibited apoptosis. Further analysis showed that CARMA3 depletion downregulated, and its overexpression upregulated cyclin D1, Bcl-2, and p-IκB levels. In conclusion, our study demonstrated that CARMA3 is overexpressed in breast cancers. CARMA3 facilitates proliferation and inhibits apoptosis through nuclear factor-kappaB signaling.     

HGF upregulates CXCR4 expression in gliomas via NF-κB: implications for glioma cell migration

Invasion is a hallmark of malignant gliomas and is the main reason for therapeutic failure and recurrence of the tumor. CXCR4 is a key chemokine receptor implicated in glioma cell migration whose expression is regulated by hypoxia. Here, we report that hepatocyte growth factor (HGF) upregulated CXCR4 protein expression in glioma cells. HGF pre-treatment increased migration of U87MG and LN229 glioma cells towards the CXCR4 ligand, stromal cell-derived factor-1α (SDF-1α). AMD3100, a CXCR4 inhibitor, inhibited the increased migration of HGF pre-treated LN229 glioma cells towards SDF-1α. Following exposure to HGF and hypoxia, both cell lines showed nuclear translocation of NF-κB (p65). The HGF- and hypoxia-induced nuclear translocation of NF-κB (p65) involved phosphorylation and degradation of IκB-α. Knock-down of NF-κB expression inhibited the induction of CXCR4 expression in response to HGF, but not to hypoxia. However, knock-down of NF-κB expression inhibited the induction of CXCR4 expression in response to hypoxia in the presence of HGF. NF-κB mediated migration towards SDF-1α in response to HGF. Knock-down of NF-κB expression resulted in decreased migration of HGF pre-treated glioma cells towards SDF-1α. Therefore, HGF upregulates CXCR4 expression via NF-κB and leads to enhanced migration. To our knowledge, this is the first report to show that a crosstalk mediated by NF-κB exists between the SDF-1α/CXCR4 and HGF/c-Met axes relevant to glioma cell migration. These findings imply that effective inhibition of glioma invasion should be directed against several ligand/receptor signaling pathways.     

Garcinol inhibits tumour cell proliferation,angiogenesis, cell cycle progression and induces apoptosis via NF-κB inhibition in oral cancer

Garcinol, a polyisoprenylated benzophenone is extracted from the rind of the fruit of Garcinia indica, a plant found extensively in tropical regions. Its ability to inhibit tumour growth has been demonstrated in certain cancers. In this study, we evaluated the potential anti-tumour effects of garcinol on oral squamous cell carcinoma (OSCC) cells. Three OSCC cell lines (SCC-4, SCC-9 and SCC-25) were treated with garcinol for 48 h and its effect on growth and proliferation, clonogenic survival, cell cycle and apoptosis was studied by MTT, clonogenic assay, propidium iodide (PI) staining and annexin-V binding assay, respectively. The alteration in expression of NF-κB and COX-2 was studied by western blot analysis and that of VEGF by ELISA. Garcinol treatment significantly (p?<?0.001) inhibited the growth and proliferation and colony formation of OSCC cells with a concomitant induction of apoptosis and cell cycle arrest. It did not show toxic effect on normal cells. It significantly (p?<?0.05) reduced the expression of NK-κB and COX-2 expression in treated cells as compared to untreated controls besides inhibiting VEGF expression. It appears that garcinol exerts anti-proliferative, pro-apoptotic, cell-cycle regulatory and anti-angiogenic effects on oral cancer cells through inhibition of NF-κB and COX-2. Thus, garcinol may be developed as a potential chemopreventive and/or chemotherapeutic agent for treatment of oral squamous cell carcinoma.     

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) promotes glioma cell invasion through induction of NF-κB-inducing kinase (NIK) and noncanonical NF-κB signaling

Background

High-grade gliomas are one of the most invasive and therapy-resistant cancers. We have recently shown that noncanonical NF-κB/RelB signaling is a potent driver of tumorigenesis and invasion in the aggressive, mesenchymal subtype of glioma. However, the relevant signals that induce activation of noncanonical NF-κB signaling in glioma and its function relative to the canonical NF-κB pathway remain elusive.

Methods

The ability of tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) to regulate NF-κB signaling and promote tumor progression was investigated in both established and primary high-grade glioma tumor lines using a three-dimensional (3-D) collagen invasion assay. The roles of specific NF-κB proteins in regulating glioma cell invasion and expression of Matrix Metalloproteinase 9 (MMP9) in response to TWEAK were evaluated using shRNA-mediated loss-of-function studies. The ability of NF-κB-inducing kinase (NIK) to promote glioma growth in vivo was investigated using an orthotopic xenograft mouse model.

Results

In glioma cells that display elevated noncanonical NF-κB signaling, loss of RelB attenuates invasion without affecting RelA expression or phosphorylation and RelB is sufficient to promote invasion in the absence of RelA. The cytokine TWEAK preferentially activates the noncanonical NF-κB pathway through induction of p100 processing to p52 and nuclear accumulation of both RelB and p52 without activating the canonical NF-κB pathway. Moreover, TWEAK, but not TNFα, significantly increases NIK mRNA levels. TWEAK also promotes noncanonical NFκB-dependent MMP9 expression and glioma cell invasion. Finally, expression of NIK is sufficient to increase gliomagenesis in vivo.

Conclusions

Our data establish a key role for NIK and noncanonical NF-κB in mediating TWEAK-induced, MMP-dependent glioma cell invasion. The findings also demonstrate that TWEAK induces noncanonical NF-κB signaling and signal-specific regulation of NIK mRNA expression. Together, these studies reveal the important role of noncanonical NF-κB signaling in regulating glioma invasiveness and highlight the therapeutic potential of targeting activation of NIK in this deadly disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-014-0273-1) contains supplementary material, which is available to authorized users.