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Pericyte coverage in GL261 control tumors is shown (CollagenIV, red; desmin, green)

Supplementary Figure 3 demonstrates that dual anti-angiogenic and PD-1 therapy normalized the vasculature at the morphological level

Supplementary Figure 1 showing PD-L1 expression in human GBM

Gating strategy for the delineation of glioma tumor infiltrating lymphocytes.

Legends for movies 1-4

File with supporting methods and tables

Supplementary Figure 2 illustrates PD-L1 expression in the GL261 glioma model

Supplementary Figure Legends 1 - 3 are displayed

Pericyte coverage after PD-1 monotherapy (CollagenIV, red; desmin, green)

Aflibercept/AMG386 combined with anti-PD-1 therapy improves the vasculature as evidenced by desmin staining (CollagenIV, red; desmin, green)

Glioblastoma (GBM) is a non-T-cell–inflamed cancer characterized by an immunosuppressive microenvironment that impedes dendritic cell maturation and T-cell cytotoxicity. Proangiogenic cytokines such as VEGF and angiopoietin-2 (Ang-2) have high expression in glioblastoma in a cell-specific manner and not only drive tumor angiogenesis and vascular permeability but also negatively regulate T-lymphocyte and innate immune cell responses. Consequently, the alleviation of immunosuppression might be a prerequisite for successful immune checkpoint therapy in GBM. We here combined antiangiogenic and immune checkpoint therapy and demonstrated improved therapeutic efficacy in syngeneic, orthotopic GBM models. We observed that blockade of VEGF, Ang-2, and programmed cell death protein-1 (PD-1) significantly extended survival compared with vascular targeting alone. In the GBM microenvironment, triple therapy increased the numbers of CTLs, which inversely correlated with myeloid-derived suppressor cells and regulatory T cells. Transcriptome analysis of GBM microvessels indicated a global vascular normalization that was highest after triple therapy. Our results propose a rationale to overcome tumor immunosuppression and the current limitations of VEGF monotherapy by integrating the synergistic effects of VEGF/Ang-2 and PD-1 blockade to reinforce antitumor immunity through a normalized vasculature.

Supplementary Table S1.

Purpose: Glioblastomas are the most common and most deadly primary brain tumors. Here, we evaluated the chemotherapeutic effect of the natural polyphenol curcumin on glioma cells in vitro and in vivo using an immunocompetent orthotopic mouse model.Experimental Design: Curcumin's effects on proliferation, cell cycle, migration, invasion, JAK/STAT3 signaling, STAT3 target gene expression, and STAT3C rescue experiments were determined in murine glioma cell lines in vitro. Therapeutic effects of curcumin in vivo were evaluated in tumor-bearing mice fed a Western-type diet fortified with curcumin (0.05%, w/w) and in control animals. Tumor growth patterns and survival were evaluated by immunohistochemistry, morphometric analyses, and Kaplan–Meier plots.Results:In vitro, curcumin inhibited JAK1,2/STAT3 tyrosine-phosphorylation in a dose-dependent fashion in murine glioma cell lines. Real-time RT-PCR revealed that curcumin downregulated transcription of the STAT3 target genes c-Myc, MMP-9, Snail, and Twist, and of the proliferation marker Ki67. Curcumin dose-dependently suppressed cell proliferation by inducing a G2/M phase arrest. In wound healing and Matrigel invasion assays, curcumin treatment resulted in a dose-dependent attenuation of the glioma cells' migratory and invasive behavior, which could be rescued by constitutively active STAT3C. In vivo, curcumin intake reduced the growth and midline crossing of intracranially implanted tumors and proliferation of tumor cells ensuing in significant long-term survival compared with control diet.Conclusion: This preclinical study shows that curcumin is capable of suppressing malignant glioma growth in vitro and in vivo. Our data suggest that the pharmacologically safe agent curcumin holds promise for clinical application in glioma therapy. Clin Cancer Res; 16(23); 5781–95. ©2010 AACR.

Glioblastoma (GBM) is a non-T-cell–inflamed cancer characterized by an immunosuppressive microenvironment that impedes dendritic cell maturation and T-cell cytotoxicity. Proangiogenic cytokines such as VEGF and angiopoietin-2 (Ang-2) have high expression in glioblastoma in a cell-specific manner and not only drive tumor angiogenesis and vascular permeability but also negatively regulate T-lymphocyte and innate immune cell responses. Consequently, the alleviation of immunosuppression might be a prerequisite for successful immune checkpoint therapy in GBM. We here combined antiangiogenic and immune checkpoint therapy and demonstrated improved therapeutic efficacy in syngeneic, orthotopic GBM models. We observed that blockade of VEGF, Ang-2, and programmed cell death protein-1 (PD-1) significantly extended survival compared with vascular targeting alone. In the GBM microenvironment, triple therapy increased the numbers of CTLs, which inversely correlated with myeloid-derived suppressor cells and regulatory T cells. Transcriptome analysis of GBM microvessels indicated a global vascular normalization that was highest after triple therapy. Our results propose a rationale to overcome tumor immunosuppression and the current limitations of VEGF monotherapy by integrating the synergistic effects of VEGF/Ang-2 and PD-1 blockade to reinforce antitumor immunity through a normalized vasculature.

The macrophage migration inhibitory factor (MIF) receptor CD74 is overexpressed in various neoplasms, mainly in hematologic tumors, and currently investigated in clinical studies. CD74 is quickly internalized and recycles after antibody binding, therefore it constitutes an attractive target for antibody-based treatment strategies. CD74 has been further described as one of the most up-regulated molecules in human glioblastomas. To assess the potential relevance for anti-CD74 treatment, we determined the cellular source and clinicopathologic relevance of CD74 expression in human gliomas by immunohistochemistry, immunofluorescence, immunoblotting, cell sorting analysis and quantitative polymerase chain reaction (qPCR). Furthermore, we fractionated glioblastoma cells and glioma-associated microglia/macrophages (GAMs) from primary tumors and compared CD74 expression in cellular fractions with whole tumor lysates. Our results show that CD74 is restricted to GAMs in vivo, while being absent in tumor cells, the latter strongly expressing its ligand MIF. Most interestingly, a higher amount of CD74-positive GAMs was associated with beneficial patient survival constituting an independent prognostic parameter and with an anti-tumoral M1 polarization. In summary, CD74 expression in human gliomas is restricted to GAMs and positively associated with patient survival. In conclusion, CD74 represents a positive prognostic marker most probably because of its association with an M1-polarized immune milieu in high-grade gliomas.

The oral bioavailability of curcuminoids is low, but can be enhanced by incorporation into micelles. The major curcuminoid curcumin has antitumor effects on glioblastoma cells in vitro and in vivo. We therefore aimed to determine intratumoral concentrations and the clinical tolerance of highly bioavailable micellar curcuminoids in glioblastoma patients.Thirteen glioblastoma patients ingested 70 mg micellar curcuminoids [57.4 mg curcumin, 11.2 mg demethoxycurcumin (DMC), and 1.4 mg bis-demethoxycurcumin (BDMC)] three times per day for 4 days (total amount of 689 mg curcumin, 134 mg DMC, and 17 mg BDMC) prior to planned resection of their respective brain tumors. Tumor and blood samples were taken during the surgery and analyzed for total curcuminoid concentrations. (31)P magnetic resonance spectroscopic imaging was performed before and after curcuminoid consumption.Ten patients completed the study. The mean intratumoral concentration of curcumin was 56 pg/mg of tissue (range 9-151), and the mean serum concentration was 253 ng/ml (range 129-364). Inorganic phosphate was significantly increased within the tumor (P = 0.034). The mean ratio of phosphocreatine to inorganic phosphate decreased, and the mean intratumoral pH increased (P = 0.08) after curcuminoid intervention.Oral treatment with micellar curcuminoids led to quantifiable concentrations of total curcuminoids in glioblastomas and may alter intratumoral energy metabolism.

Chronic inflammation and oxidative stress increase with advancing age and appear to be involved in the pathogenesis of coronary heart disease, the leading cause of death worldwide. There is a need for animal models that reflect the increases in pro-inflammatory cytokines and oxidative damage observed during aging in humans. We therefore aimed to investigate the suitability of the fast-aging senescence-accelerated mouse-prone 8 (SAMP8) strain and its normally aging control senescence-accelerated mouse-resistant 1 (SAMR1) to study the age-dependent changes in cytokines, oxidative damage and antioxidants in the heart. To this end, 2-months-old male SAMR1 and SAMP8 mice were fed a Western type diet (control groups) for 5 months. Two groups of SAMP8 mice were simultaneously fed identical diets fortified with 0.5 g curcumin or 1.0 g Ginkgo biloba extract EGb 761(®) per kg diet. Heart tissue homogenates were analysed for protein carbonyls, glutathione, glutathione disulfide, methionine, cysteine and uric acid as well as the cytokines tumor-necrosis factor-α, interleukin-1β, interleukin-6, and monocyte chemoattractant protein 1. Neither the strain (SAMR1 or SAMP8) nor antioxidant intake (curcumin or EGb 761(®)) affected the concentrations of the measured parameters. In conclusion, our data do not support the suitability of the SAMP8 and SAMR1 strains as a model to study age-related changes in pro-inflammatory cytokines and oxidative stress parameters in the heart.

Purpose: Glioblastomas are the most common and most deadly primary brain tumors. Here, we evaluated the chemotherapeutic effect of the natural polyphenol curcumin on glioma cells in vitro and in vivo using an immunocompetent orthotopic mouse model. Experimental Design: Curcumin's effects on proliferation, cell cycle, migration, invasion, JAK/STAT3 signaling, STAT3 target gene expression, and STAT3C rescue experiments were determined in murine glioma cell lines in vitro. Therapeutic effects of curcumin in vivo were evaluated in tumor-bearing mice fed a Western-type diet fortified with curcumin (0.05%, w/w) and in control animals. Tumor growth patterns and survival were evaluated by immunohistochemistry, morphometric analyses, and Kaplan–Meier plots. Results: In vitro, curcumin inhibited JAK1,2/STAT3 tyrosine-phosphorylation in a dose-dependent fashion in murine glioma cell lines. Real-time RT-PCR revealed that curcumin downregulated transcription of the STAT3 target genes c-Myc, MMP-9, Snail, and Twist, and of the proliferation marker Ki67. Curcumin dose-dependently suppressed cell proliferation by inducing a G2/M phase arrest. In wound healing and Matrigel invasion assays, curcumin treatment resulted in a dose-dependent attenuation of the glioma cells' migratory and invasive behavior, which could be rescued by constitutively active STAT3C. In vivo, curcumin intake reduced the growth and midline crossing of intracranially implanted tumors and proliferation of tumor cells ensuing in significant long-term survival compared with control diet. Conclusion: This preclinical study shows that curcumin is capable of suppressing malignant glioma growth in vitro and in vivo. Our data suggest that the pharmacologically safe agent curcumin holds promise for clinical application in glioma therapy. Clin Cancer Res; 16(23); 5781–95. ©2010 AACR.

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.

Object The aim of this study was to develop and characterize a new orthotopic, syngeneic, transplantable mouse brain tumor model by using the cell lines Tu-9648 and Tu-2449, which were previously isolated from tumors that arose spontaneously in glial fibrillary acidic protein (GFAP)-v-src transgenic mice. Methods Striatal implantation of a 1-μl suspension of 5000 to 10,000 cells from either clone into syngeneic B6C3F1 mice resulted in tumors that were histologically identified as malignant gliomas. Prior subcutaneous inoculations with irradiated autologous cells inhibited the otherwise robust development of a microscopically infiltrating malignant glioma. Untreated mice with implanted tumor cells were killed 12 days later, when the resultant gliomas were several millimeters in diameter. Immunohistochemically, the gliomas displayed both the astroglial marker GFAP and the oncogenic form of signal transducer and activator of transcription–3 (Stat3). This form is called tyrosine-705 phosphorylated Stat3, and is found in many malignant entities, including human gliomas. Phosphorylated Stat3 was particularly prominent, not only in the nucleus but also in the plasma membrane of peripherally infiltrating glioma cells, reflecting persistent overactivation of the Janus kinase/Stat3 signal transduction pathway. The Tu-2449 cells exhibited three non-random structural chromosomal aberrations, including a deletion of the long arm of chromosome 2 and an apparently balanced translocation between chromosomes 1 and 3. The GFAP-v-src transgene was mapped to the pericentromeric region of chromosome 18. Conclusions The high rate of engraftment, the similarity to the high-grade malignant glioma of origin, and the rapid, locally invasive growth of these tumors should make this murine model useful in testing novel therapies for human malignant gliomas.

Photodynamic therapy (PDT) is widely used to treat preneoplastic skin lesions and non-melanoma skin tumours. Studies analyzing the effects of PDT on malignant melanoma have yielded conflicting results. On the one hand, melanoma cell lines in culture as well as cell lines transplanted into experimental animals were sensitive to PDT. On the other hand, spontaneous melanomas of human patients responded poorly to most PDT regimens tested so far. Here, we analyzed effects of 5-aminolaevulinic acid (5-ALA)-based PDT on melanoma cell lines and on experimental melanomas. To mimic the clinical situation as closely as possible, metallothionein-I/ret (MT-ret) mice, a transgenic model of skin melanoma development, were used. Optimal doses of 5-ALA as well as energy doses and power densities were determined in vitro using a cell line (Mel25) established by us from a melanoma of an MT-ret transgenic mouse as well as commercially available human and mouse melanoma cell lines. Treatment with light irradiation alone had no effect. In combination with 5-ALA, however, this illumination readily induced the death of all mouse and human melanoma cell lines examined. Still, 5-ALA PDT caused only minor focal regressive changes including haemorrhages and fibrosis of MT-ret melanomas in vivo and did not significantly delay tumour growth. These results show that, even though MT-ret melanoma cells are vulnerable to 5-ALA PDT in vitro, malignant MT-ret melanomas in vivo are quite resistant to this type of therapy at doses which are highly effective in vitro.

Interleukin (IL)-6 is a pleiotropic cytokine that has been shown to inhibit the growth of early stage and to promote the proliferation of advanced stage melanoma cells in vitro. In patients with metastasizing melanomas, highly increased IL-6 blood levels correlate with a poor response to chemotherapy and a worse overall prognosis, suggesting that IL-6 promotes melanoma progression in vivo. Here, we analyzed the role of IL-6 in melanoma development and progression in a transgenic mouse model. We bred IL-6-deficient mice with MT-ret transgenic animals predisposed for melanomas. While MT-ret transgenic animals develop severe melanosis of the skin and subcutis and subsequent melanomas at an incidence of 80% during their first year of life, MT-ret mice devoid of IL-6 developed preneoplastic melanosis and consecutive melanomas significantly less frequently (47%; P < 0.05). Moreover, the tumors were significantly smaller in the groups of MT-ret mice lacking one (P < 0.05) or both (P < 0.01) copies of the IL-6 gene. Immunoblot analysis revealed that ret transgene expression was not reduced in the skin of mice lacking IL-6, indicating that the observed decrease of melanoma incidence and of tumor sizes was not because of a down-regulation of transgene expression. Taken together, these results indicate that IL-6 enhances both the development of melanoma precursor lesions and the subsequent growth of the resulting tumors in the MT-ret model of melanoma development.

Interleukin-6 (IL-6) expression is strongly correlated with the degree of human glioma malignancy and necessary for tumor formation in a mouse model of spontaneous astrocytomas. Yet, exactly how IL-6 contributes to malignant progression of these brain tumors is still unclear. We have scrutinized the mechanism of transcriptional activation of vascular endothelial growth factor (VEGF) expression by IL-6 in the mouse brain and in glioblastoma cells. We demonstrate here that IL-6 drives transcriptional upregulation of VEGF in astrocytes in vivo using glial fibrillary acidic protein (GFAP)-IL-6/VEGF-green fluorescent protein (GFP) double transgenic mice. We further show that IL-6-induced VEGF transcription and VEGF secretion by human glioblastoma cells is dependent on signal transducer and activator of transcription 3 (STAT3). By progressive 5'-deletion analysis we defined the minimal VEGF promoter region for IL-6-responsiveness to nucleotides -88/-50. Surprisingly, this promoter region is rich in GC-boxes and does not contain STAT3 binding elements. Electrophoretic mobility shift and supershift assays revealed binding of Sp1 and Sp3 to the -88/-50 element upon IL-6 stimulation. Interestingly, preincubation with STAT3 antibody prevented the binding of Sp1 and Sp3 to the -88/-50 element, indicating that STAT3 is involved in IL-6-driven Sp1/Sp3 protein-DNA complex formation. Physical interaction of STAT3 and Sp1 was demonstrated by coimmunoprecipitation. The functional relevance of the STAT3/Sp1 association was corroborated by transient transfection experiments, which showed that overexpression of constitutively active STAT3 increased the minimal VEGF promoter activity. Taken together, our study suggests that IL-6 promotes tumor angiogenesis in gliomas and describes a novel transcriptional activation mechanism for STAT3 in the context of a STAT3 binding element (SBE)-free promoter.

The pleiotropic cytokine interleukin-6 (IL-6) contributes to malignant progression and apoptosis resistance of various cancer types. Although IL-6 is elevated in malignant gliomas, and glioma cells respond to IL-6, its functional role in gliomagenesis is unclear. We have investigated this role of IL-6 in a mouse model of spontaneous astrocytoma by crossbreeding glial fibrillary acidic protein (GFAP)-viral src oncogene transgenic mice with IL-6-deficient mice. We show here that ablation of IL-6 prevents tumour formation in these predisposed animals, but did not affect preneoplastic astrogliosis. Moreover, we demonstrate phosphorylation and nuclear translocation of the transcription factor signal transducer and activator of transcription (STAT)3, a prerequisite for IL-6 signalling, in 51 human gliomas WHO grade II-IV and all experimental mouse tumours investigated. Together with the observation that STAT3 activation increases with malignancy, these findings indicate an important role for IL-6 in the development and malignant progression of astrocytomas.

Alterations in small GTPase mediated signal transduction pathways have emerged as a central step in the molecular pathogenesis of glioblastoma (GBM), the most common malignant brain tumor in adults. Farnesylpyrophosphate (FPP) and geranylgeranylpyrophosphate (GGPP) are derived from mevalonate, whose production is catalyzed by 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase. Prenylation by FPP and GGPP is required for membrane insertion and oncogenic function of Ras- and Rho-proteins, within the stimulation of the Ras-Raf-MEK-ERK pathway. A straightforward prediction from HMG-CoA reductase inhibitor studies is that statins decrease FPP and GGPP levels and diminish ERK signaling ensuring less proliferation and migration of cancer cells. Perillyl alcohol (POH), a naturally occurring monoterpene inhibits prenyltransferases and is able to inhibit cancer cell growth, but the underlying mechanism is still unclear. We here report that lovastatin (LOV) and POH impair the regulation of the mevalonate- and the Ras-Raf-MEK-ERK pathway in U87 and U343 glioblastoma cells. Both compounds affected the post-translational modification of H-Ras and Rac1. While LOV diminished the substrates of the transferase reaction that catalyze prenylation, POH inhibited the enzymes itself. Our data highlight the impact of isoprenoids for post-translational modification of small GTPases promoting proliferation, migration and invasion capabilities in glioma cells.

The macrophage migration inhibitory factor (MIF) receptor CD74 is overexpressed in various neoplasms, mainly in hematologic tumors, and currently investigated in clinical studies. CD74 is quickly internalized and recycles after antibody binding, therefore it constitutes an attractive target for antibody‐based treatment strategies. CD74 has been further described as one of the most up‐regulated molecules in human glioblastomas. To assess the potential relevance for anti‐CD74 treatment, we determined the cellular source and clinicopathologic relevance of CD74 expression in human gliomas by immunohistochemistry, immunofluorescence, immunoblotting, cell sorting analysis and quantitative polymerase chain reaction (qPCR). Furthermore, we fractionated glioblastoma cells and glioma‐associated microglia/macrophages (GAMs) from primary tumors and compared CD74 expression in cellular fractions with whole tumor lysates. Our results show that CD74 is restricted to GAMs in vivo, while being absent in tumor cells, the latter strongly expressing its ligand MIF. Most interestingly, a higher amount of CD74‐positive GAMs was associated with beneficial patient survival constituting an independent prognostic parameter and with an anti‐tumoral M1 polarization. In summary, CD74 expression in human gliomas is restricted to GAMs and positively associated with patient survival. In conclusion, CD74 represents a positive prognostic marker most probably because of its association with an M1‐polarized immune milieu in high‐grade gliomas.

Angiogenesis is a prerequisite for solid tumor growth. Glioblastoma multiforme, the most common malignant brain tumor, is characterized by extensive vascular proliferation. We previously showed that transgenic mice expressing a GFAP-v-src fusion gene in astrocytes develop low-grade astrocytomas that progressively evolve into hypervascularized glioblastomas. Here, we examined whether tumor progression triggers angiogenetic signals. We found abundant transcription of vascular endothelial growth factor (VEGF) in neoplastic astrocytes at surprisingly early stages of tumorigenesis. VEGF and v-src expression patterns were not identical, suggesting that VEGF activation was not only dependent on v-src. Late-stage gliomas showed perinecrotic VEGF up-regulation similarly to human glioblastoma. Expression patterns of the endothelial angiogenic receptors flt-1, flk-1, tie-1, and tie-2 were similar to those described in human gliomas, but flt-1 was expressed also in neoplastic astrocytes, suggesting an autocrine role in tumor growth. In crossbreeding experiments, hemizygous ablation of the tumor suppressor genes Rb and p53 had no significant effect on the expression of VEGF, flt-1, flk-1, tie-1, and tie-2. Therefore, expression of angiogenic signals is an early event during progression of GFAP-v-src tumors and precedes hypervascularization. Given the close similarities in the progression pattern between GFAP-v-src and human gliomas, the present results suggest that these mice may provide a useful tool for antiangiogenic therapy research.

Background. Diffuse infiltration remains the fulcrum of glioblastoma’s incurability, leading inevitably to recurrence. Therefore, uncovering the pathological mechanism is imperative. Because signal transducer and activator of transcription 3 (STAT3) correlates with glioma malignancy and predicts poor clinical outcome, we determined its role in glioma single cell infiltration and tumor growth. Methods. STAT3 was silenced in Tu-2449 glioma cells via lentiviral gene transfer. Target gene expression was measured by real-time reverse transcription PCR, Western blotting, and immunohistochemistry. Microvilli were visualized by staining with wheat germ agglutinin. Migration and invasion were measured by Scratch and Matrigel chamber assays. Diffuse infiltration was studied in 350mm-thick organotypic tissue cultures over 14 days using cells tagged with enhanced green fluorescent protein and live confocal laser scanning microscopy. Survival of tumor-bearing syngeneic, immunocompetent B6C3F1 mice was analyzed by Kaplan‐Meier plots. Results. STAT3 silencing reduced cell migration and invasion in vitro and stopped single cell infiltration ex vivo, while STAT3-expressing cells disseminated through the neuropil at � 100 mm/day. STAT3 silencing reduced transcription of several tumor progression genes. Mice with intracranial STAT3 knockdown tumors had a significant (P , .0007) survival advantage over controls, yielding 27% long-term survival. STAT3 knockdown reduced podoplanin expression 50-fold and inhibited concurrent microvilli formation. STAT3 knockdown tumors exhibited a weaker podoplanin immunoreactivity compared with controls. Podoplanin staining was diffuse, preferentially at tumor margins, and absent in normal brain. Conclusions. Our results show compelling evidence that STAT3 is a key driver of diffuse infiltration and glioma growth and might therefore represent a promising target for an anti-invasive therapy.

The human foamy virus (HFV) is a complex retrovirus that contains several regulatory and auxiliary bel genes besides the gag, pol, and env genes. In contrast to the gene products of bel 1 and bel 2/bet that were identified previously, the Bel 3 protein has not been described to date. Here we report the identification of Bel 3 in HFV-infected cells by immunoprecipitation, indirect immunofluorescence, and expression cloning under the control of a strong heterologous promoter. Bel 3 was immunoprecipitated with an antiserum directed against a bacterially expressed and purified form of recombinant Bel 3 antigen. Bel 3 was found to be expressed in low amounts in the cytoplasm of HFV-infected cells and to migrate with an apparent molecular mass of 19.4 kDa on electrophoresis in SDS-polyacrylamide gels, consistent with the calculated value of 18.2 kDa. Radioimmunoprecipitation of HFV-infected cell lysates with the hyperimmune serum against Bel 3 revealed at least two additional immunoreactive bands of 15.5 and 10.6 kDa. The results indicate that Bel 3 was labile, because it was partially degraded even at early time points after infection. On transfection and expression in transfected COS cells, recombinant Bel 3 was immunoprecipitated and migrated in three polypeptide bands of 18.7, 14.8, and 9.3 kDa under denaturing conditions. In the absence of reducing agents, the bacterially expressed and purified recombinant Bel 3 protein of 16.1 kDa can form homodimers of 30 kDa.

Background New drugs are constantly sought after to improve the survival of patients with malignant gliomas. The ideal substance would selectively target tumor cells without eliciting toxic side effects. Here, we report on the anti-proliferative, anti-migratory, and anti-invasive properties of the natural, nontoxic compound Curcumin observed in five human glioblastoma (GBM) cell lines in vitro. Methods We used monolayer wound healing assays, modified Boyden chamber trans-well assays, and cell growth assays to quantify cell migration, invasion, and proliferation in the absence or presence of Curcumin at various concentrations. Levels of the transcription factor phospho-STAT3, a potential target of Curcumin, were determined by sandwich-ELISA. Subsequent effects on transcription of genes regulating the cell cycle were analyzed by quantitative real-time PCR. Effects on apoptosis were determined by caspase assays. Results Curcumin potently inhibited GBM cell proliferation as well as migration and invasion in all cell lines contingent on dose. Simultaneously, levels of the biologically active phospho-STAT3 were decreased and correlated with reduced transcription of the cell cycle regulating gene c-Myc and proliferation marking Ki-67, pointing to a potential mechanism by which Curcumin slows tumor growth. Conclusions Curcumin is part of the diet of millions of people every day and is without known toxic side effects. Our data show that Curcumin bears anti-proliferative, anti-migratory, and anti-invasive properties against GBM cells in vitro. These results warrant further in vivo analyses and indicate a potential role of Curcumin in the treatment of malignant gliomas.

The objective of this study was to investigate the therapeutic effects of doxorubicin bound to polysorbate-coated nanoparticles that had previously been shown to significantly enhance survival in the ortho-topic rat 101/8 glioblastoma model. Tumor-bearing animals were subjected to chemotherapy using doxorubicin in solution (Dox-sol) or doxorubicin bound to polysorbate 80-coated poly(butyl cyanoacrylate) nanoparticles (Dox-np) injected intravenously on Days 2, 5 and 8 post tumor implantation. The antitumor effect was assessed on Days 10, 14 and 18 post tumor implantation. Tumors showed signs of malignancy including invasion of brain tissue, brisk mitotic activity, microvascular proliferation, necrosis and increased proliferation resembling human glioblastoma. Dox-np produced a considerably more pronounced antitumor effect exhibited as a reduced tumor size, lower proliferation, and a decreased necrotic area compared to Dox-sol and to untreated control groups. A drastic effect of Dox-np on vascularization indicated an antiangiogenic mode of action.

Interleukin-6 (IL-6), a major cytokine with diverse effects on cells mainly of the immune and hematopoietic systems, has been linked to several neurological disorders such as acquired immune deficiency syndrome dementia, multiple sclerosis, and Alzheimer's disease. Central nervous system (CNS)-specific expression of IL-6 caused neurodegeneration, massive gliosis, and vascular proliferation in transgenic mice. However, the effects of systemically circulating IL-6 and its receptor IL-6Ralpha on the CNS are unknown. IL-6Ralpha is the specific component of the IL-6 receptor system and hence an important co-factor of IL-6. IL-6Ralpha is bioactive in a membrane-bound and in a soluble (s) form. We investigated the effects of systemically elevated levels of either human IL-6 or human sIL-6Ralpha or both on the CNS of transgenic mice. Although IL-6 and sIL-6Ralpha single transgenic mice were free of neurological disease, IL-6/sIL-6Ralpha double-transgenic mice showed neurological signs, such as tremor, gait abnormalities, and paresis. However, these mice also frequently showed prominent general weakness probably because of the systemic effects of IL-6/IL-6Ralpha such as liver damage and plasmacytomas. IL-6/sIL-6Ralpha transgenic mice exhibited massive reactive gliosis. Lack of signs of neuronal breakdown versus ample astrogliosis suggested that astrocytes were selectively affected in these mice. There was neither vascular proliferation nor inflammatory infiltration. Ultrastructural analysis revealed blood-brain barrier (BBB) changes manifested by hydropic astrocytic end-feet. However, albumin immunohistochemistry did not reveal major BBB leakage. Our results indicate that increased and constitutive systemic expression of IL-6 together with its soluble receptor sIL-6Ralpha is less harmful to the brain than to other organs. The BBB remains primarily intact. IL-6/IL-6Ralpha, however, might be directly responsible for the selective activation of astrocytes.

Transgenic animal models for neurocarcinogenesis have provided significant insights into the molecular mechanisms underlying carcinogenic processes, including those which affect the nervous system. In view of the very rapid pace of acquisition of knowledge, it is not possible to cover all transgenic mouse models for neural tumors. Instead, this article discusses some of the most important technical innovations for manipulation of the mammalian genome (notably the various methods for targeted genome modifications, as well as the technology for introducing large DNA fragments into the germ line of mice), and presents a selection of the transgenic mouse models which are proving most promising for furthering our understanding of the pathogenetic basis of cancer in the nervous system.

We have generated a transgenic mouse model for astrocytoma by expressing the v-src kinase under control of the glial fibrillary acidic protein (GFAP) gene regulatory elements in astrocytes. Abnormal astrogliosis was observed in all transgenic animals already at 2 weeks postnatally, frequently followed by the development of dysplastic changes. Later, small proliferative foci arose, and overt astrocytoma developed in the brain and spinal cord in 14.4% of mice after a follow up time of 65 weeks. While early lesions were histologically consistent with low-grade astrocytoma, at later stages most tumors were highly mitotic and frankly malignant. Vascular endothelial growth factor (VEGF) was expressed by tumor cells already at early stages, suggesting induction by v-src, and it was most pronounced in pseudopalisading cells surrounding necrotic areas, implying additional upregulation by hypoxia. In larger lesions, mitotic activity and expression of flk-1, the cognate receptor of VEGF were induced in endothelial cells. Therefore, end-stage tumors mimicked the morphological and molecular characteristics of human glioblastoma multiforme. Time course and stochastic nature of the process indicate that v-src did not suffice for malignant transformation, and that astrocytomas were the result of a multistep process necessitating co-operation of additional genetic events.

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults. GBM cells are highly resistant to apoptosis induced by antitumor drugs and radiotherapy resulting in cancer progression. We assessed whether a systems medicine approach, analysing the ability of tumor cells to execute apoptosis could be utilized to predict the response of GBM patients to treatment. Concentrations of the key proapoptotic proteins procaspase-3, procaspase-9, Smac and Apaf-1 and the antiapopotic protein XIAP were determined in a panel of GBM cell lines and GBM patient tumor resections. These values were used as input for APOPTO-CELL, a systems biological based mathematical model built to predict cellular susceptibility to undergo caspase activation. The modeling was capable of accurately distinguishing between GBM cells that die or survive in response to treatment with temozolomide in 10 of the 11 lines analysed. Importantly the results obtained using GBM patient samples show that APOPTO-CELL was capable of stratifying patients according to their progression-free survival times and predicted the ability of tumor cells to support caspase activation in 16 of the 21 GBM patients analysed. Calculating the susceptibility to apoptosis execution may be a potent tool in predicting GBM patient therapy responsiveness and may allow for the use of APOPTO-CELL in a clinical setting.

The human foamy virus is a complex retrovirus that codes for several regulatory bel genes in addition to the conventional gag, pol, and env genes. The bel 3 gene is located in the 3' part of the viral genome comparable to that of the superantigen of the mouse mammary tumor virus. Superantigens bound to major histocompatibility complex (MHC) class II molecules have been shown to stimulate T cells in a V beta-specific manner. The recombinant Bel 3 protein purified to near homogeneity was assayed in vitro to determine whether or not it functions as a superantigen that stimulates human T lymphocytes expressing particular V beta T cell receptor (TCR) chains. Therefore, an analysis including all known human V beta elements was performed. The expression of different V beta chains of the TCR was analyzed by reverse transcription of the V beta RNAs and subsequent amplification of the corresponding V beta cDNA elements by polymerase chain reaction in unstimulated, phytohemaggluttinin (PHA)- and Bel 3-stimulated human T lymphocytes. In addition, eight monoclonal antibodies directed against particular V beta family members were used to determine any change in the expression of the remaining known V beta elements upon treatment with PHA and Bel 3. The comparative V beta-specific transcriptional analysis revealed that the in vitro expression of the V beta 18 chain was specifically and strongly expanded in Bel 3-stimulated human T cells, a property characteristic for a superantigen.

Glioblastoma multiforme (GBM) is the most aggressive and malignant tumour of the central nervous system. It is characterised by a rapid clinical course and extremely unfavourable prognosis. GBM cells are highly resistant to apoptosis induced by anti-tumour drugs and radiotherapy, resulting in cancer progression. A critical determinant of a cell's susceptibility to undergo apoptosis is the balance of pro-apoptotic and antiapoptotic proteins within a cell. Both commercially bought GBM cells lines (A172 and U87) and a cell line recently derived from a GBM patient (MZ294), were resistant to apoptosis induction upon treatment with temozolomide (TMZ; 150 μM) and TNF-related apoptosis inducing ligand (TRAIL; 100 ng/ml) as assessed by MTT cell survival assay and Hoechst staining. However, they were shown to undergo apoptosis after treatment with r-roscovitine (20 μM) in a time dependent manner. R-roscovitine, a cyclin-dependent kinase inhibitor, has previously been shown to induce apoptosis in multiple cell types via downregulation of the anti-apoptotic protein myeloid cell leukemia-1 (Mcl-1). We also saw that the induction of apoptosis in MZ294 cells was associated with a downregulation of Mcl-1 protein expression. Western blot analysis of resections from GBM patients demonstrated a negative correlation between the expression of the anti-apoptotic protein Mcl-1 and progression free survival times of patients after treatment, highlighting an important role for Mcl-1 in GBM progression. Since Mcl-1 was shown to be an important survival protein in GBM patient samples and cell lines, we assessed if the downregulation of Mcl-1 could sensitize MZ294 cells to TMZ and TRAIL and further augment r-roscovitine-induced apoptosis. Accordingly, MZ294 cells were transfected with a shRNA targeting Mcl-1 and subsequently treated with TMZ (150 μM), TRAIL (100 ng/ml) or r-roscovitine (20 μM) for 48 h. Knockdown of Mcl-1 alone increased the percentage of MZ294 cells undergoing apoptosis and enhanced their sensitivity to TMZ, TRAIL and r-roscovitine treatment. We next assessed if the pharmacological targeting of Mcl-1, a more clinically relevant approach, could also yield similar results. Co-treatment of MZ294 cells with r-roscovitine (20 μM) and TRAIL (100 ng/ml) or r-roscovitine (20 μM) and TMZ (150 μM) for 48 h synergistically increased the induction of apoptosis when compared to either drug treatment alone. Finally and perhaps most crucially similar observations were noted upon treatment of MZ294 neurospheres, the cancer stem cell population of this cell line. Collectively this body of work highlights that the efficacy of potential therapies for GBM patients can be increased if the critical levels of Mcl-1 expression are concomitantly reduced. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr C41.