Glial tumors progress to malignant grades by heightened proliferation and relentless dispersion throughout the central nervous system. Understanding genetic and biochemical processes that foster these behaviors is likely to reveal specific and effective targets for therapeutic intervention. Our current report shows that the fibroblast growth factor-inducible 14 (Fn14), a member of the tumor necrosis factor (TNF) receptor superfamily, is expressed at high levels in migrating glioma cells in vitro and invading glioma cells in vivo. Forced Fn14 overexpression stimulates glioma cell migration and invasion, and depletion of Rac1 by small interfering RNA inhibits this cellular response. Activation of Fn14 signaling by the ligand TNF-like weak inducer of apoptosis (TWEAK) stimulates migration and up-regulates expression of Fn14; this TWEAK effect requires Rac1 and nuclear factor-KB (NF-KB) activity. The Fn14 promoter region contains NF-KB binding sites, which mediate positive feedback causing sustained overexpression of Fn14 and enduring glioma cell invasion. Furthermore, Fn14 gene expression levels increase with glioma grade and inversely correlate with patient survival. These results show that the Fn14 cascade operates as a positive feedback mechanism for elevated and sustained Fn14 expression. Such a feedback loop argues for aggressive targeting of the Fn14 axis as a unique and specific driver of glioma malignant behavior.

We investigated whether cilengitide could amplify the antitumor effects of radiotherapy in an orthotopic rat glioma xenograft model. Cilengitide is a specific inhibitor of av series integrins, and acts as an antiangiogenic. U251 human glioma cells express avb3 and avb5 integrins. We used in vitro assays of adhesion and growth of tumor and endothelial cells to evaluate cytotoxicity and the potential for cilengitide to enhance radiation toxicity. Treatment was then evaluated in an orthotopic model to evaluate synergy with therapeutic radiation in vivo. In vitro, cilengitide blocked cell adhesion, but did not influence the effects of radiation on U251 cells; cilengitide strongly amplified radiation effects on endothelial cell survival. In vivo, radiotherapy prolonged the survival of U251 tumor-bearing rats from 50 to over 110 days. Cotreatment with cilengitide and radiation dramatically amplified the effects of radiation, producing survival over 200 days and triggering an enhanced apoptotic response and suppression of tumor growth by histology at necropsy. Signaling pathways activated in the tumor included NFjb, a documented mediator of cellular response to radiation. Because cilengitide has a short plasma halflife (t ½ 20 min), antiangiogenic scheduling typically uses daily injections. We found that a single dose of cilengitide (4 mg/kg) given between 4 and 12 hr prior to radiation was sufficient to produce the same effect. Our results demonstrate that blockade of av integrins mediates an unanticipated rapid potentiation of radiation, and suggests possible clinical translation for glioma therapy. ' 2008 Wiley-Liss, Inc.Key words: glioma; cilengitide; integrin; radiation; animal model Integrins control cell attachment to extracellular matrices (ECMs) and participate in cellular defense against genotoxic assaults. 1 These defense mechanisms are a major factor in the resistance of solid malignancies to radiotherapy. In this in vivo study, we examine the effects of an inhibitor of av-integrins, cilengitide, on the growth of gliomas in response to external beam radiotherapy. Malignant gliomas, including anaplastic astrocytoma and glioblastoma multiforme (GBM), are the most common primary brain tumors, afflicting some 6/100,000 individuals annually within the United States. 2 Current treatment options include surgery, radiation therapy (RT) and chemotherapy. But the efficacy of treatment is limited by the infiltrative nature of GBMs, by sustained tumor angiogenesis, and by a marked resistance to chemo and radiotherapies. Indeed, clinical prognosis is poor and the median survival from diagnosis of 12 months in GBM has not changed appreciably over a quarter century. 3 Gliomas, and especially anaplastic gliomas, infiltrate and spread great distances in the brain from a peripheral zone of infiltrating cells in the highly vascularized cellular rim of tumor that surrounds a central necrotic core. 4 The infiltrating tumor cells cause an almost inevitable local recurrence and clinical progression. 5 Recurrence following surger...

Background: Glioblastoma multiforme (GBM) is the most common primary intracranial tumor and despite recent advances in treatment regimens, prognosis for affected patients remains poor. Active cell migration and invasion of GBM cells ultimately lead to ubiquitous tumor recurrence and patient death.

Although astrocytic brain tumors do not metastasize systemically, during tumorigenesis glioma cells adopt an invasive phenotype that is poorly targeted by conventional therapies; hence, glioma patients die of recurrence from the locally invasive tumor population. Our work is aimed at identifying and validating novel therapeutic targets and biomarkers in invasive human gliomas. Transcriptomes of invasive glioma cells relative to stationary cognates were produced from a three-dimensional spheroid in vitro invasion assay by laser capture microdissection and whole human genome expression microarrays. Qualitative differential expression of candidate invasion genes was confirmed by quantitative reverse transcription-PCR, clinically by immunohistochemistry on tissue microarray, by immunoblotting on surgical specimens, and on two independent gene expression data sets of glial tumors. Cell-based assays and ex vivo brain slice invasion studies were used for functional validation. We identify mitogen-activated protein kinase (MAPK) kinase 3 (MKK3) as a key activator of p38 MAPK in glioma; MKK3 activation is strongly correlated with p38 activation in vitro and in vivo. We further report that these members of the MAPK family are strong promoters of tumor invasion, progression, and poor patient survival. Inhibition of either candidate leads to significantly reduced glioma invasiveness in vitro. Consistent with the concept of synthetic lethality, we show that inhibition of invasion by interference with these genes greatly sensitizes arrested glioma cells to cytotoxic therapies. Our findings therefore argue that interference with MKK3 signaling through a novel treatment combination of p38 inhibitor plus temozolomide heightens the vulnerability of glioma to chemotherapy. [Mol Cancer Ther 2007;6(4):1212 -22]

The relationship between glucose concentrations in interstitial fluid (ISF) and blood has generated great interest due to its importance in minimally invasive and noninvasive techniques for measuring blood glucose. The relationship between glucose levels in dermal ISF, and capillary and venous blood was studied with the dermal ISF samples obtained using the suction blister technique. The study was conducted with intensely managed diabetics whose blood glucose levels were manipulated so as to induce rapid changes in blood glucose levels. Glucose levels in the three compartments exhibited high correlations both when individual subjects were considered separately and when data from all subjects were combined. No significant time lag during glucose excursions was observed among the ISF, and capillary and venous glucose levels.