Integrin involvement in glioblastoma multiforme: possible regulation by NF-kappaB

Fluoride in the Central Nervous System and Its Potential Influence on the Development and Invasiveness of Brain Tumours-A Research Hypothesis

The purpose of this review is to attempt to outline the potential role of fluoride in the pathogenesis of brain tumours, including glioblastoma (GBM). In this paper, we show for the first time that fluoride can potentially affect the generally accepted signalling pathways implicated in the formation and clinical course of GBM. Fluorine compounds easily cross the blood-brain barrier. Enhanced oxidative stress, disruption of multiple cellular pathways, and microglial activation are just a few examples of recent reports on the role of fluoride in the central nervous system (CNS). We sought to present the key mechanisms underlying the development and invasiveness of GBM, as well as evidence on the current state of knowledge about the pleiotropic, direct, or indirect involvement of fluoride in the regulation of these mechanisms in various tissues, including neural and tumour tissue. The effects of fluoride on the human body are still a matter of controversy. However, given the growing incidence of brain tumours, especially in children, and numerous reports on the effects of fluoride on the CNS, it is worth taking a closer look at these mechanisms in the context of brain tumours, including gliomas.

Algorithmically Deduced FREM2 Molecular Pathway Is a Potent Grade and Survival Biomarker of Human Gliomas

Gliomas are the most common malignant brain tumors with high mortality rates. Recently we showed that the FREM2 gene has a role in glioblastoma progression. Here we reconstructed the FREM2 molecular pathway using the human interactome model. We assessed the biomarker capacity of FREM2 expression and its pathway as the overall survival (OS) and progression-free survival (PFS) biomarkers. To this end, we used three literature and one experimental RNA sequencing datasets collectively covering 566 glioblastomas (GBM) and 1097 low-grade gliomas (LGG). The activation level of deduced FREM2 pathway showed strong biomarker characteristics and significantly outperformed the FREM2 expression level itself. For all relevant datasets, it could robustly discriminate GBM and LGG (p < 1.63 × 10-13, AUC > 0.74). High FREM2 pathway activation level was associated with poor OS in LGG (p < 0.001), and low PFS in LGG (p < 0.001) and GBM (p < 0.05). FREM2 pathway activation level was poor prognosis biomarker for OS (p < 0.05) and PFS (p < 0.05) in LGG with IDH mutation, for PFS in LGG with wild type IDH (p < 0.001) and mutant IDH with 1p/19q codeletion(p < 0.05), in GBM with unmethylated MGMT (p < 0.05), and in GBM with wild type IDH (p < 0.05). Thus, we conclude that the activation level of the FREM2 pathway is a potent new-generation diagnostic and prognostic biomarker for multiple molecular subtypes of GBM and LGG.

Extracellular Matrix Proteins Confer Cell Adhesion-Mediated Drug Resistance Through Integrin α v in Glioblastoma Cells

Chemotherapy resistance to glioblastoma (GBM) remains an obstacle that is difficult to overcome, leading to poor prognosis of GBM patients. Many previous studies have focused on resistance mechanisms intrinsic to cancer cells; the microenvironment surrounding tumor cells has been found more recently to have significant impacts on the response to chemotherapeutic agents. Extracellular matrix (ECM) proteins may confer cell adhesion-mediated drug resistance (CAMDR). Here, expression of the ECM proteins laminin, vitronectin, and fibronectin was assessed in clinical GBM tumors using immunohistochemistry. Then, patient-derived GBM cells grown in monolayers on precoated laminin, vitronectin, or fibronectin substrates were treated with cilengitide, an integrin inhibitor, and/or carmustine, an alkylating chemotherapy. Cell adhesion and viability were quantified. Transcription factor (TF) activities were assessed over time using a bioluminescent assay in which GBM cells were transduced with lentiviruses containing consensus binding sites for specific TFs linked to expression a firefly luciferase reporter. Apoptosis, mediated by p53, was analyzed by Western blotting and immunocytofluorescence. Integrin α_v activation of the FAK/paxillin/AKT signaling pathway and effects on expression of the proliferative marker Ki67 were investigated. To assess effects of integrin α_v activation of AKT and ERK pathways, which are typically deregulated in GBM, and expression of epidermal growth factor receptor (EGFR), which is amplified and/or mutated in many GBM tumors, shRNA knockdown was used. Laminin, vitronectin, and fibronectin were abundant in clinical GBM tumors and promoted CAMDR in GBM cells cultured on precoated substrates. Cilengitide treatment induced cell detachment, which was most pronounced for cells cultured on vitronectin. Cilengitide treatment increased cytotoxicity of carmustine, reversing CAMDR. ECM adhesion increased activity of NFκB and decreased that of p53, leading to suppression of p53-mediated apoptosis and upregulation of multidrug resistance gene 1 (MDR1; also known as ABCB1 or P-glycoprotein). Expression of Ki67 was correlative with activation of the integrin α_v-mediated FAK/paxillin/AKT signaling pathway. EGFR expression increased with integrin α_v knockdown GBM cells and may represent a compensatory survival mechanism. These results indicate that ECM proteins confer CAMDR through integrin α_v in GBM cells.

Altered Adhesion and Migration of Human Mesenchymal Stromal Cells under Febrile Temperature Stress Involves NF-κβ Pathway

Mesenchymal stromal cells (MSCs) are clinically beneficial for regenerative treatment of chronic inflammation and autoimmune disorders. However, to attain maximum efficacy from the transplanted MSCs, evaluation of its interaction with the microenvironment, becomes critical. Fever being an important hallmark of inflammation, we investigated the effect of febrile temperature stress on adhesion and migration of umbilical cord-derived MSCs. 40 °C-exposure altered cellular morphology with significant cell flattening, delayed cell-matrix de-adhesion response and slower migration of MSCs, accompanied by suppressed directionality ratio and cell trajectory. Corresponding to the observed changes, mRNA expression of extracellular matrix genes like COLs and VTN were upregulated, while matrix metalloproteinase MMP-1, showed a significant downregulation. NF-κβ pathway inhibition at 40 °C, led to reversal of gene expression pattern, cell spreading, de-adhesion dynamics and migration rate. Independent knockdown of p65 and p53 at 40 °C indicated inhibitory role of p65/p53/p21 axis in regulation of MMP-1 expression. P21 inhibits JNK activity, and JNK pathway inhibition at 40 °C resulted in further downregulation of MMP-1. Hence, our study provides the first evidence of cell migration getting adversely affected in MSCs under elevated temperature stress due to an inverse relationship between p65/p53/p21 and MMP1 with a possible involvement of the JNK pathway.

Adhesion- and stress-related adaptation of glioma radiochemoresistance is circumvented by β1 integrin/JNK co-targeting

Resistance of cancer stem-like and cancer tumor bulk cells to radiochemotherapy and destructive infiltration of the brain fundamentally influence the treatment efficiency to cure of patients suffering from Glioblastoma (GBM). The interplay of adhesion and stress-related signaling and activation of bypass cascades that counteract therapeutic approaches remain to be identified in GBM cells. We here show that combined inhibition of the adhesion receptor β1 integrin and the stress-mediator c-Jun N-terminal kinase (JNK) induces radiosensitization and blocks invasion in stem-like and patient-derived GBM cultures as well as in GBM cell lines. In vivo, this treatment approach not only significantly delays tumor growth but also increases median survival of orthotopic, radiochemotherapy-treated GBM mice. Both, in vitro and in vivo, effects seen with β1 integrin/JNK co-inhibition are superior to the monotherapy. Mechanistically, the in vitro radiosensitization provoked by β1 integrin/JNK targeting is caused by defective DNA repair associated with chromatin changes, enhanced ATM phosphorylation and prolonged G2/M cell cycle arrest. Our findings identify a β1 integrin/JNK co-dependent bypass signaling for GBM therapy resistance, which might be therapeutically exploitable.

αVβ3 Integrin regulates astrocyte reactivity

Background

Neuroinflammation involves cytokine release, astrocyte reactivity and migration. Neuronal Thy-1 promotes DITNC1 astrocyte migration by engaging α_Vβ₃ Integrin and Syndecan-4. Primary astrocytes express low levels of these receptors and are unresponsive to Thy-1; thus, inflammation and astrocyte reactivity might be necessary for Thy-1-induced responses.

Methods

Wild-type rat astrocytes (TNF-activated) or from human SOD1^G93A transgenic mice (a neurodegenerative disease model) were used to evaluate cell migration, Thy-1 receptor levels, signaling molecules, and reactivity markers.

Results

Thy-1 induced astrocyte migration only after TNF priming. Increased expression of α_Vβ₃ Integrin, Syndecan-4, P2X7R, Pannexin-1, Connexin-43, GFAP, and iNOS were observed in TNF-treated astrocytes. Silencing of β₃ Integrin prior to TNF treatment prevented Thy-1-induced migration, while β₃ Integrin over-expression was sufficient to induce astrocyte reactivity and allow Thy-1-induced migration. Finally, hSOD1^G93A astrocytes behave as TNF-treated astrocytes since they were reactive and responsive to Thy-1.

Conclusions

Therefore, inflammation induces expression of α_Vβ₃ Integrin and other proteins, astrocyte reactivity, and Thy-1 responsiveness. Importantly, ectopic control of β₃ Integrin levels modulates these responses regardless of inflammation.

Electronic supplementary material

The online version of this article (10.1186/s12974-017-0968-5) contains supplementary material, which is available to authorized users.

Molecular Targeting of Integrins and Integrin-Associated Signaling Networks in Radiation Oncology

Radiation and chemotherapy are the main pillars of the current multimodal treatment concept for cancer patients. However, tumor recurrences and resistances still hamper treatment success regardless of advances in radiation beam application, particle radiotherapy, and optimized chemotherapeutics. To specifically intervene at key recurrence- and resistance-promoting molecular processes, the development of potent and specific molecular-targeted agents is demanded for an efficient, safe, and simultaneous integration into current standard of care regimens. Potential targets for such an approach are integrins conferring structural and biochemical communication between cells and their microenvironment. Integrin binding to extracellular matrix activates intracellular signaling for regulating essential cellular functions such as survival, proliferation, differentiation, adhesion, and cell motility. Tumor-associated characteristics such as invasion, metastasis, and radiochemoresistance also highly depend on integrin function. Owing to their dual functionality and their overexpression in the majority of human malignancies, integrins present ideal and accessible targets for cancer therapy. In the following chapter, the current knowledge on aspects of the tumor microenvironment, the molecular regulation of integrin-dependent radiochemoresistance and current approaches to integrin targeting are summarized.

Potentiation of cytotoxic chemotherapy by growth hormone-releasing hormone agonists

The dismal prognosis of malignant brain tumors drives the development of new treatment modalities. In view of the multiple activities of growth hormone-releasing hormone (GHRH), we hypothesized that pretreatment with a GHRH agonist, JI-34, might increase the susceptibility of U-87 MG glioblastoma multiforme (GBM) cells to subsequent treatment with the cytotoxic drug, doxorubicin (DOX). This concept was corroborated by our findings, in vivo, showing that the combination of the GHRH agonist, JI-34, and DOX inhibited the growth of GBM tumors, transplanted into nude mice, more than DOX alone. In vitro, the pretreatment of GBM cells with JI-34 potentiated inhibitory effects of DOX on cell proliferation, diminished cell size and viability, and promoted apoptotic processes, as shown by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide proliferation assay, ApoLive-Glo multiplex assay, and cell volumetric assay. Proteomic studies further revealed that the pretreatment with GHRH agonist evoked differentiation decreasing the expression of the neuroectodermal stem cell antigen, nestin, and up-regulating the glial maturation marker, GFAP. The GHRH agonist also reduced the release of humoral regulators of glial growth, such as FGF basic and TGFβ. Proteomic and gene-expression (RT-PCR) studies confirmed the strong proapoptotic activity (increase in p53, decrease in v-myc and Bcl-2) and anti-invasive potential (decrease in integrin α3) of the combination of GHRH agonist and DOX. These findings indicate that the GHRH agonists can potentiate the anticancer activity of the traditional chemotherapeutic drug, DOX, by multiple mechanisms including the induction of differentiation of cancer cells.

The functions and applications of RGD in tumor therapy and tissue engineering

Arginine-Glycine-Aspartic (RGD), is the specific recognition site of integrins with theirs ligands, and regulates cell-cell and cell-extracellular matrix interactions. The RGD motif can be combined with integrins overexpressed on the tumor neovasculature and tumor cells with a certain affinity, becoming the new target for imaging agents, and drugs, and gene delivery for tumor treatment. Further, RGD as a biomimetic peptide can also promote cell adherence to the matrix, prevent cell apoptosis and accelerate new tissue regeneration. Functionalizing material surfaces with RGD can improve cell/biomaterial interactions, which facilitates the generation of tissue-engineered constructs. This paper reviews the main functions and advantages of RGD, describes the applications of RGD in imaging agents, drugs, gene delivery for tumor therapy, and highlights the role of RGD in promoting the development of tissue engineering (bone regeneration, cornea repair, artificial neovascularization) in recent years.

Suppression of the proliferation of human U-87 MG glioblastoma cells by new antagonists of growth hormone-releasing hormone in vivo and in vitro

Five-year survival of patients afflicted with glioblastoma multiforme (GBM) is rare, making this cancer one of the most feared malignancies. Previously, we reported that growth hormone-releasing hormone (GHRH) is a potent growth factor in cancers. The present work evaluated the effects of two antagonistic analogs of GHRH (MIA-604 and MIA-690) on the proliferation of U-87 MG GBM tumors, in vivo as well as in vitro. Both analogs were administered subcutaneously and dose-dependently inhibited the growth of tumors transplanted into nude mice (127 animals in seven groups). The analogs also inhibited cell proliferation in vitro, decreased cell size, and promoted apoptotic and autophagic processes. Both antagonists stimulated contact inhibition, as indicated by the expression of the E-cadherin-β-catenin complex and integrins, and decreased the release of humoral regulators of glial growth such as FGF, PDGFβ, and TGFβ, as revealed by genomic or proteomic detection methods. The GHRH analogs downregulated other tumor markers (Jun-proto-oncogene, mitogen-activated protein kinase-1, and melanoma cell adhesion molecule), upregulated tumor suppressors (p53, metastasis suppressor-1, nexin, TNF receptor 1A, BCL-2-associated agonist of cell death, and ifκBα), and inhibited the expression of the regulators of angiogenesis and invasion (angiopoetin-1, VEGF, matrix metallopeptidase-1, S100 calcium binding protein A4, and synuclein-γ). Our findings indicate that GHRH antagonists inhibit growth of GBMs by multiple mechanisms and decrease both tumor cell size and number.

Integrin αvβ3 promotes vitronectin gene expression in human ovarian cancer cells by implicating rel transcription factors

We previously showed that integrin αvβ3 expression upon engagement by its major ligand vitronectin (VN) correlated with enhanced human ovarian cancer cell adhesion, motility, and proliferation, by triggering intracellular signaling events, ultimately leading to altered gene expression. In the present study, we characterized cellular VN expression as a function of αvβ3 and noticed significant upregulation of VN protein which was reflected by elevated VN gene transcription. In order to identify specific transcription factors involved in the αvβ3-regulatory effect on VN, we generated different VN promoter mutants. We noticed that disruption of the DNA consensus motif for Rel proteins did not only prominently reduce VN promoter activity but, moreover, led to a loss of responsiveness to αvβ3, suggesting a crucial role of Rel proteins in αvβ3-provoked VN induction. In cell migration studies, we confirmed increased cell motility as a function of αvβ3/VN which was further enhanced by raising cellular Rel transcription factor levels. Thus, the data of the present study elucidated a positive feedback regulatory loop on VN expression by αvβ3 implicating transcription factors of the Rel family. Hence by altering the composition of the extracellular matrix upon additional VN synthesis and deposition, tumor cells might be enabled to modulate their surrounding reactive microenvironment towards enhanced αvβ3/VN-interactions and, consequently, intrinsic intracellular signaling events affecting cancer progression.

Short hairpin RNA-mediated fibronectin knockdown delays tumor growth in a mouse glioma model

Glioblastoma multiforme is the most common and lethal primary brain tumor. Glioma progression depends on the rapid proliferation of tumor cells accompanied by an acute immunosuppressive environment, facilitated mainly by tumor infiltration of regulatory T cells (Tregs). In this study, we characterize the role of fibronectin, a high-molecular weight extracellular matrix glycoprotein secreted by tumor cells, in controlling glioma progression and in mediating immunosuppression. Fibronectin binds to membrane-spanning integrin receptors and plays an important role in cell signaling, in defining cellular shape, in mobility, and in regulating the cell cycle. We found that inhibition of fibronectin expression in glioma cells, using short hairpin RNA-mediated silencing of gene expression, delayed cell proliferation in vitro. This delayed growth is explained, in part, by the observed reduced expression of integrin β(1) fibronectin receptor, which was restored by the inhibition of proteosomal activity. In our analysis of the downstream signaling targets of integrin β(1), we demonstrated reduced phosphorylation of Src kinase and STAT-3. We also observed reduced survivin expression that induced a three-fold increased accumulation of fibronectin-knockdown cells in the G(2)/M phase. In an experimental animal model, the fibronectin knockdown tumors had a mean survival advantage of 23 days over wild-type tumors. Moreover, brain samples of animals bearing fibronectin-knockdown tumors showed delayed Treg recruitment. Collectively, we propose that fibronectin is a key mediator of glioma progression because its inhibition delays both tumor progression and immunosuppression.

Difucosylated oligosaccharide Lewis Y is contained within integrin αvβ3 on RL95-2 cells and required for endometrial receptivity

OBJECTIVE

To investigate whether Lewis Y (LeY) carried by integrin αvβ3 influences integrin αvβ3-mediated adhesion in an in vitro implantation model.

DESIGN

Laboratory research.

SETTING

Reproduction and glycobiology research laboratory.

INTERVENTION(S)

Specific antibody blockage of LeY or integrin αvβ3 and knockdown of FUT4 expression in RL95-2 cells by transient transfection of FUT4 siRNA.

MAIN OUTCOME MEASURE(S)

The expression of integrin αvβ3 and LeY in both endometrial tissues and RL95-2 cells was measured. LeY carried by integrin αvβ3 was identified by examining the immunoprecipitated integrin αvβ3. The effect of knocking down FUT4 on the expression of integrin αvβ3 and LeY and their impact on the adhesion of JAR cells to the RL95-2 cells were assessed.

RESULT(S)

Integrin αvβ3 and LeY are expressed in both secretory-stage human endometrial tissue and in RL95-2 cells. Although integrin αvβ3 carries LeY, knocking down FUT4 expression only reduces the expression of LeY but not of integrin αvβ3. Knocking down FUT4, antibody blockade of LeY or integrin αvβ3 consistently decreases the adhesion of JAR cells to the RL95-2 cells and prevents focal adhesion kinase (FAK) phosphorylation.

CONCLUSION(S)

LeY carried by integrin αvβ3 plays a critical role on the attachment of JAR cells to the RL95-2 cells and activates integrin αvβ3/FAK signaling.

Expression of the constitutively activated RelA/NF-kappaB in human astrocytic tumors and the in vitro implication in the regulation of urokinase-type plasminogen activator, migration, and invasion

Although malignant gliomas are highly invasive tumors, a characteristic that contributes to the commonly observed therapeutic failures and local disease recurrences, the molecular events that regulate invasion in these tumors remain poorly understood. Because the transcription factor RelA/NF-kappaB has been shown to regulate invasion during several cellular processes, we have examined immunohistochemically expression of the constitutively activated RelA/NF-kappaB in tissues obtained from 49 astrocytic tumors [8 diffuse astrocytomas, 9 anaplastic astrocytomas (AAs) and 32 glioblastomas (GBMs)]. In addition, we examined the in vitro effects of antisense oligonucleotides and curcumin on the expression and activation of RelA/NF-kappaB, urokinase-type plasminogen activator (u-PA) expression, migration, and invasion in the T98G glioma cell line. Expression of the constitutively activated RelA/NF-kappaB was observed in 2 (25%) of 8 cases of diffuse astrocytomas, 5 (55.6%) of 9 cases of AAs, and 30 (93.8%) of 32 cases of GBMs. This expression was significantly correlated with the malignant potential in astrocytic tumors (P < 0.001). Moreover, antisense oligonucleotides and curcumin inhibited phorbol-12-myristate-13-acetate (PMA)-induced RelA/NF-kappaB expression or activation (or both), down-regulated u-PA expression, and reduced the migration and invasive potentials of T98G glioma cells. Thus, the expression of constitutively activated RelA/NF-kappaB is associated with malignancy potential in astrocytic tumors and may play a critical role in the regulation of u-PA expression and invasiveness in gliomas. RelA/NF-kappaB may therefore be an intriguing candidate for studies aimed at understanding and prevention of the invasiveness of gliomas.

Epithelial-derived fibronectin expression, signaling, and function in intestinal inflammation

Fibronectin (FN) is a multifunctional extracellular matrix protein that plays an important role in cell proliferation, adhesion, and migration. FN expression or its role in colitis is not known. The goal of this study is to characterize FN expression, regulation, and role during intestinal inflammation. Wild-type and transgenic mice expressing luciferase under the control of the human FN promoter, given water or 3% dextran sodium sulfate, were used as animal models of colitis. The Caco2-BBE model intestinal epithelial cell line was used for in vitro studies. FN protein is abundantly expressed by surface epithelial cells in the normal colon. Immunohistochemistry and luciferase assay in mice expressing the FN promoter linked to luciferase demonstrated that FN synthesis was up-regulated during colitis, during both the acute phase and the healing phase. In vitro experiments demonstrated that FN increased the expression of the FN integrin receptor alpha5beta1 in a dose- and time-dependent manner. FN also induced the expression and activation of NF-kappaB. Further, FN potentiated Caco2-BBE cell attachment and wound healing, which was inhibited by RGD peptide as well as NF-kappaB inhibitors MG-132 and 1-pyrrolidinecarbodithioic acid, ammonium salt. In conclusion, FN is abundantly expressed and synthesized by colonic epithelial cells. FN is transcriptionally up-regulated in epithelial cells during both the dextran sodium sulfate-induced colitic and the recovery phase. FN enhances cell attachment and wound healing, which is dependent on binding to the integrin receptor and the NF-kappaB signaling. Together our data show that epithelial-derived FN potentiates cell attachment and wound healing through epithelial-matrix interactions and that FN expression may have important implications for maintaining normal epithelial integrity as well as regulating epithelial response to injury during colitis.

Human cytomegalovirus induces cellular tyrosine kinase signaling and promotes glioma cell invasiveness

Given our previous findings that human cytomegalovirus (HCMV) nucleic acids and proteins are expressed in human malignant glioma in vivo, we investigated cellular signaling events associated with HCMV infection of human glioma and astroglial cells. HCMV infection caused rapid activation of the phosphatidylinositol-3 kinase (PI-3K) effector AKT kinase in human astro-glial and fibroblast cells, and induced tyrosine phosphorylation of phospholipase Cgamma (PLCgamma). Co-immunoprecipitation experiments revealed association of the p85 regulatory subunit of PI-3K with a high-molecular weight protein phosphorylated on tyrosine, following short-term exposure to HCMV. In contrast to a previous report, we were unable to confirm the identity of this high-molecular weight protein as being the epidermal growth factor receptor (EGFR). Stimulation of glioma and fibroblast cell lines over-expressing EGFR with HCMV (whole virus) or soluble glycoprotein B did not induce tyrosine phosphorylation of the receptor, as did the genuine ligand, EGF. Furthermore, we found that expression levels of the human ErbB1-4 receptors were not rate-limiting for HCMV infection. Dispensability of EGFR function during early HCMV infection was substantiated by demonstration of viral immediate early gene expression in cells lacking the EGFR gene, indicating that HCMV may promote oncogenic signaling pathways independently of EGFR activation. Among non-receptor cellular kinases, HCMV infection induced phosphorylation of focal adhesion kinase (FAK) Tyr397, which is indispensable for integrin-mediated cell migration and invasion. HCMV-induced FAK activation was paralleled by increased extracellular matrix-dependent migration of human malignant glioma but not normal astro-glial cells, suggesting that HCMV can selectively augment glioma cell invasiveness.

Aberrant constitutive activation of nuclear factor kappaB in glioblastoma multiforme drives invasive phenotype

Several recent studies have shown that aberrant constitutive activation of nuclear factor kappaB (NF-kappaB) is present in a variety of cancers including gliomas. NF-kappaB is known to play important roles in the physiological regulation of diverse cellular processes such as inflammation, growth and immunity. In contrast, aberrant activation of this latent transcription factor promotes cancer cell migration, invasion and resistance to chemotherapy. Here we show by electro-mobility shift assay (EMSA) and immuno-staining that constitutive NF-kappaB activation is present in various malignant glioma cell lines as well as in primary cultures derived from tumor tissue. This activation was not serum dependent and it led to high IL-8 gene transcription and protein production. Over-expression of an I-kappaB super-repressor (I-kappaB SR) transgene completely blocked constitutive NF-kappaB activation, nuclear localization and transcription of some but not all NF-kappaB regulated genes indicating that NF-kappaB signaling in glioma cells is I-kappaB dependent. Surprisingly, over-expression of IkappaBSR did not have any effect on the transcription levels of anti-apoptotic genes in these glioma cultures and cell lines. Down-regulation of NF-kappaB activation reduced invasion of glioma cells through matrigel. Collectively these data suggest that aberrant constitutive activation of NF-kappaB in glioblastoma cells promotes their invasive phenotype. Interruption of this aberrant NF-kappaB activity may help reduce the spread of this infiltrative tumor.

Expression of integrins in cerebral arteriovenous and cavernous malformations

OBJECTIVE

To assess and compare levels and patterns of expression for integrins alphavbeta1, alphavbeta3, and alphavbeta5 in arteriovenous malformations (AVMs) and cavernous malformations (CCMs) of the brain.

MATERIALS AND METHODS

Specimens from 10 AVM and 10 CCM lesions were selected from 112 patients with AVMs and 97 patients with CCMs who were treated microsurgically in the Department of Neurosurgery, Marmara University, Istanbul, Turkey. Sections were immunohistochemically stained with antibodies for integrins alphavbeta1, alphavbeta3, and alphavbeta5. Separate histological layers of the vascular wall were evaluated, and levels of expression were graded using a four-tier system.

RESULTS

Integrin alphavbeta1 was more strongly expressed in AVMs than in CCMs. This difference was most pronounced in the endothelium and subendothelium/media. Integrin alphavbeta3 was more strongly expressed in CCM endothelium than in AVM endothelium (average grades, 0.9 and 0.4, respectively). All 10 of the CCM lesions expressed integrin alphavbeta5 in the endothelium, whereas only five of the AVMs showed minimal expression of this molecule in the endothelium.

CONCLUSION

Current scientific understanding of the roles integrins play in angiogenesis is far from complete. The levels and patterns of expression for these molecules in the histological layers of the vascular walls of AVMs and CCMs provide some clues about the complex biological activities of integrins in these lesions. If one accepts the premise that immunohistochemistry has its inherent methodological problems, integrins alphavbeta1, alphavbeta3, and alphavbeta5 are expressed in AVMs and CCMs in different ways that may be linked to stages of angiogenic maturation. Integrin alphavbeta1 is expressed more strongly in endothelium and subendothelium/media of AVMs than in the corresponding layers of CCMs. Integrins alphavbeta3 and alphavbeta5 are expressed more strongly in CCM endothelium than in AVM endothelium. In addition, integrin alphavbeta5 staining was stronger in CCM subendothelium than AVM subendothelium/media.

Glioblastoma cells deficient in DNA-dependent protein kinase are resistant to cell death

DNA-dependent protein kinase (DNA-PK), a nuclear serine/threonine kinase, is responsible for the DNA double-strand break repair. Cells lacking or with dysfunctional DNA-PK are often associated with mis-repair, chromosome aberrations, and complex exchanges, all of which are known to contribute to the development of human cancers including glioblastoma. Two human glioblastoma cell lines were used in the experiment, M059J cells lacking the catalytic subunit of DNA-PK, and their isogenic but DNA-PK proficient counterpart, M059K. We found that M059K cells were much more sensitive to staurosporine (STS) treatment than M059J cells, as demonstrated by MTT assay, TUNEL detection, and annexin-V and propidium iodide (PI) staining. A possible mechanism responsible for the different sensitivity in these two cell lines was explored by the examination of Bcl-2, Bax, Bak, and Fas. The cell death stimulus increased anti-apoptotic Bcl-2 and decreased pro-apoptotic Bcl-2 members (Bak and Bax) and Fas in glioblastoma cells deficient in DNA-PK. Activation of DNA-PK is known to promote cell death of human tumor cells via modulation of p53, which can down-regulate the anti-apoptotic Bcl-2 member proteins, induce pro-apoptotic Bcl-2 family members and promote a Bax-Bak interaction. Our experiment also demonstrated that the mode of glioblastoma cell death induced by STS consisted of both apoptosis and necrosis and the percentage of cell death in both modes was similar in glioblastoma cell lines either lacking DNA-PK or containing intact DNA-PK. Taken together, our findings suggest that DNA-PK has a positive role in the regulation of apoptosis in human glioblastomas. The aberrant expression of Bcl-2 family members and Fas was, at least in part, responsible for decreased sensitivity of DNA-PK deficient glioblastoma cells to cell death stimuli.

Non-viral delivery of ribozymes for cancer gene therapy

Ribozymes are RNA molecules with the capacity to effect sequence-specific cleavage of other transcripts. Since their initial discovery, there has been considerable interest in the development of ribozymes and other RNA therapeutics for gene therapy, particularly in the realm of cancer. However, as with other gene therapy applications, the delivery of ribozyme-based therapeutics to the target tissues of interest has represented a significant obstacle to the maturation of this technology to the clinical arena. This review will discuss the progress made so far in the use of non-viral methods for the systemic delivery of ribozymes for cancer gene therapy.

IIp45, an insulin-like growth factor binding protein 2 (IGFBP-2) binding protein, antagonizes IGFBP-2 stimulation of glioma cell invasion

Our previous studies have shown that insulin-like growth factor binding protein 2 (IGFBP-2) is frequently overexpressed in the highly invasive glioblastoma multiforme (GBM). By using a yeast two-hybrid system, we identified a gene, invasion inhibitory protein 45 (IIp45), whose protein product bound to IGFBP-2 through the thyroglobulin-RGD region of the C terminus of IGFBP-2. The IIp45 gene is located on chromosome 1p36 and has nine exons. The IIp45 protein has three SEG (segment of low compositional complexity) domains and an integrin-binding RGD motif. The IIp45 protein was not expressed in some GBMs. Functional studies showed that IIp45 inhibited GBM cell invasion both in vitro and in xenograft model. Gene expression profiling studies showed that IIp45 consistently inhibited the expression of cell invasion-associated genes, such as the transcriptional NFkappaB, and its downstream target gene, intercellular adhesion molecule 1. Thus, we report here the isolation and characterization of a gene, IIp45, whose protein product binds to IGFBP-2 and inhibits glioma cell invasion.

NF-kappaB activates fibronectin gene expression in rat hepatocytes

Fibronectin (FN) plays a role in various biological processes such as fibrosis and tumor metastasis. In this study, we investigated the regulation of FN gene expression by NF-kappaB transcription factor. Transient expression of NF-kappaB p65 increased FN promoter activity in rat hepatocytes. Deletion analysis of FN promoter localized the NF-kappaB-responsive region at the position between -1214 and -1126. Mutations in a putative NF-kappaB element (5(')-GAGAATTTCC-3(')) at -1180 blocked most of the p65-induced promoter activity. Electromobility shift assays showed that the expression of p65 induced the binding of the p65/p65 homodimer to the NF-kappaB site at -1180. Stably p65-expressing cells showed increase of promoter activity, FN protein, and its mRNA levels over control cells. Furthermore, treatment of cells with interleukin-1beta, a NF-kappaB-stimulating cytokine, also increased promoter activity, FN production, and mRNA levels. These results show that NF-kappaB activates FN gene expression by binding to the responsive element at -1180 as the p65/p65 homodimer in rat hepatocytes.

The role of alpha(v)beta(3) in prostate cancer progression

Integrin alpha(v)beta(3) is involved in varied cell biological activities, including angiogenesis, cell adhesion, and migration on several extracellular matrix components. Although alpha(v)beta(3) is not typically expressed in epithelial cells, it is expressed in macrophages, activated leukocytes, cytokine-stimulated endothelial cells, osteoclasts, and certain invasive tumors. Interestingly, the adhesion and migration of breast cancer cells on bone matrix are mediated, in part, by alpha(v)beta(3). Similar to breast cancer cells, prostate cancer cells preferentially metastasize to the bone. The biological events that mediate this metastatic pattern of prostate cancer are not well defined. This review discusses the role alpha(v)beta(3) plays in prostate cancer progression, with specific emphasis on bone metastasis and on alpha(v)beta(3) signaling in prostate cancer cells. The data suggest that alpha(v)beta(3), in part, facilitates prostate cancer metastasis to bone by mediating prostate cancer cell adhesion to and migration on osteopontin and vitronectin, which are common proteins in the bone microenvironment. These biological events require the activation of focal adhesion kinase and the subsequent activation of PI-3 kinase/Akt signaling pathway.

Identification of gene function and functional pathways by systemic plasmid-based ribozyme targeting in adult mice

To date, functional genomic studies have been confined to either cell-based assays or germline mutations, using transgenic or knockout animals. However, these approaches are often unable either to recapitulate complex biologic phenotypes, such as tumor metastasis, or to identify the specific genes and functional pathways that produce serious diseases in adult animals. Although the transcription factor NF-kappaB transactivates many metastasis-related genes in cells, the precise genes and functional-pathways through which NF-kappaB regulates metastasis in tumor-bearing hosts are poorly understood. Here, we show that the systemic delivery of plasmid-based ribozymes targeting NF-kappaB in adult, tumor-bearing mice suppressed NF-kappaB expression in metastatic melanoma cells, as well as in normal cell types, and significantly reduced metastatic spread. Plasmid-based ribozymes suppressed target-gene expression with sequence specificity not achievable by using synthetic oligonucleotide-based approaches. NF-kappaB seemed to regulate tumor metastasis through invasion-related, rather than angiogenesis-, cell-cycle- or apoptosis-related pathways in tumor-bearing mice. Furthermore, ribozymes targeting either of the NF-kappaB-regulated genes, integrin beta(3) or PECAM-1 (a ligand-receptor pair linked to cell adhesion), reduced tumor metastasis at a level comparable to NF-kappaB. These studies demonstrate the utility of gene targeting by means of systemic, plasmid-based ribozymes to dissect out the functional genomics of complex biologic phenotypes, including tumor metastasis.

Expression of nuclear factor-kappa B in hepatocellular carcinoma and its relation with the X protein of hepatitis B virus

AIM

In this study we investigated the relationship of the X protein of HBV and nuclear factor-kappa B (NF-kappa B) and the expression of NF-kappa B in human hepatocellular carcinoma tissues.

METHODS

Immunohistochemistry SP method was used to detect the expression of NF-kappa B and the X protein of HBV in human hepatocellular carcinoma tissues of 52 cases. Gene transfection mediated by lipofectamine was used to transfect the eukaryotic expression vector pCDNA3.1-HBX of HBV x gene into human hepatocellular carcinoma cell line HCC-9204 and NF-kappa B was detected.

RESULTS

NF kappa B was widely expressed in human hepatocellular carcinoma tissues in a total of 52 cases and its expression was related to the X protein of HBV. NF-kappa B was localized both in the cytoplasm and the nuclei of hepatocellular carcinoma cells in 11 cases which were positive for the X protein of HBV while in 41 cases negative for the X protein of HBV, NF-kappa B was only localized in the cytoplasm of hepatocellular carcinoma cells but translocated to the nuclei of hepatocellular carcinoma cells after the eukaryotic expression vector pCDNA3.1-HBX was transfected into HCC-9204 cells.

CONCLUSION

This study strongly suggests that the nuclear factor NF-kappa B is widely expressed in hepatocellular carcinoma tissues in different styles according to the expression of the X protein of HBV. NF-kappa B is abnormally activated in hepatocellular carcinoma, which is probably related to the X protein of HBV. The X protein of HBV can activate NF-kappa B to translocate into nuclei of hepatocellular carcinoma cells.

Cell cycle regulation of NF-kappa b-binding activity in cells from human glioblastomas

Glioblastoma multiforme is a highly malignant and anaplastic tumor of the central nervous system representing more than 50% of all malignant gliomas. The cell origin of this highly undifferentiated tumor remains obscure, although it is postulated that glioblastomas are developed from astrocytes. The rapid growth of the glioma and the state of its undifferentiation are attributed to the deregulation of several signal transduction pathways and cell cycle events. Recent studies showed diverse functions for the NF-kappa B/Rel family of inducible transcription factors including differentiation, apoptosis, oncogenesis, and cell cycle regulation. We sought to examine the level of NF-kappa B activity throughout the glioma's cell cycle. Results from band-shift studies indicated a biphasic NF-kappa B DNA-binding activity in the nuclei of cycling glioblastoma cells. We showed that NF-kappa B-binding activity maximizes in nuclear extracts at specific cell cycle stages including G0/G1, mid-late G1, and S phase. Results from Northern blotting studies revealed that the differential expression of the NF-kappa B subunits, p50 and p65, may not be responsible for cell cycle stage-specific association of NF-kappa B subunits with DNA. However, results from Western blotting analysis utilizing nuclear extracts from glioma cells throughout the cell cycle demonstrated that the nuclear accumulation of p50 and p65 perfectly correlates with their DNA-binding activity. These observations suggest that the nuclear translocation of the p50/p65 subunit of NF-kappa B in glioma cells is cell cycle stage-dependent and that is distinct from the differential mRNA expression of these genes during glioma cell cycling. The possible role of NF-kappa B in glioma cell formation and regulation of cellular genes by NF-kappa B in these tumor cells is discussed.

Activators and target genes of Rel/NF-kappaB transcription factors

The vertebrate transcription factor NF-kappaB is induced by over 150 different stimuli. Active NF-kappaB, in turn, participates in the control of transcription of over 150 target genes. Because a large variety of bacteria and viruses activate NF-kappaB and because the transcription factor regulates the expression of inflammatory cytokines, chemokines, immunoreceptors, and cell adhesion molecules, NF-kappaB has often been termed a 'central mediator of the human immune response'. This article contains a complete listing of all NF-kappaB inducers and target genes described to date. The collected data argue that NF-kappaB functions more generally as a central regulator of stress responses. In addition, NF-kappaB activation blocks apoptosis in several cell types. Coupling stress responsiveness and anti-apoptotic pathways through the use of a common transcription factor may result in increased cell survival following stress insults.