Glucose transporter Glut1 controls diffuse invasion phenotype with perineuronal satellitosis in diffuse glioma microenvironment.

BACKGROUND: Gliomas typically escape surgical resection and recur due to their "diffuse invasion" phenotype, enabling them to infiltrate diffusely into the normal brain parenchyma. Over the past 80 years, studies have revealed 2 key features of the "diffuse invasion" phenotype, designated the Scherer's secondary structure, and include perineuronal satellitosis (PS) and perivascular satellitosis (PVS). However, the mechanisms are still unknown. METHODS: We established a mouse glioma cell line (IG27) by manipulating the histone H3K27M mutation, frequently harboring in diffuse intrinsic pontine gliomas, that reproduced the diffuse invasion phenotype, PS and PVS, following intracranial transplantation in the mouse brain. Further, to broadly apply the results in this mouse model to human gliomas, we analyzed data from 66 glioma patients. RESULTS: Increased H3K27 acetylation in IG27 cells activated glucose transporter 1 (Glut1) expression and induced aerobic glycolysis and TCA cycle activation, leading to lactate, acetyl-CoA, and oncometabolite production irrespective of oxygen and glucose levels. Gain- and loss-of-function in vivo experiments demonstrated that Glut1 controls the PS of glioma cells, that is, attachment to and contact with neurons. GLUT1 is also associated with early progression in glioma patients. CONCLUSIONS: Targeting the transporter Glut1 suppresses the unique phenotype, "diffuse invasion" in the diffuse glioma mouse model. This work leads to promising therapeutic and potential useful imaging targets for anti-invasion in human gliomas widely.

A new mutation of congenital methemoglobinemia exacerbated after methylene blue treatment.

Case: Methylene blue is useful for the treatment of methemoglobinemia. However, even after the patient's methemoglobin (metHb) rate has improved, careful observation is important because they could have undiagnosed congenital methemoglobinemia. In this case, a 67-year-old man underwent gastrointestinal endoscopy with the use of lidocaine for local anesthesia. During the examination, he complained of dyspnea and had low SpO2 despite normal PaO2 and SaO2. He was transferred to our department as a suspected case of acquired methemoglobinemia. Outcome: The patient's metHb level was 26.2%. We administered methylene blue i.v. and his metHb level subsequently decreased to 1.6%. However, his metHb level gradually increased to 18.2%, and we suspected that he had congenital methemoglobinemia. We administered riboflavin and ascorbic acid orally, and his metHb level decreased to 6.4%. We also obtained genomic DNA from the patient and identified a novel variant of CYB5R3. Conclusion: We report a novel variant of congenital methemoglobinemia that deteriorated after methylene blue treatment.

Current trends in mouse models of glioblastoma.

Glioblastoma is the most deadly brain tumor type and is characterized by a severe and high rate of angiogenesis, remaining an incurable disease in the majority of cases. Mechanistic understanding of glioblastoma initiation and progression is complicated by the complexity of genetic and/or environmental initiating events and lack of clarity regarding the cell or tissue of origin. To determine these mechanisms, mouse models that recapitulate the molecular and histological characteristics of glioblastoma are required. Unlike in other malignancies, viral-mediated mouse models of glioblastoma rather than chemically induced mouse models have been developed because of its sensitivity to viruses. Based on recent molecular analyses reported for human glioblastoma, this review critically evaluates genetically engineered, xenograft, allograft, viral-mediated, and chemically induced mouse models of glioblastoma. Further, we focus on the clinical value of these models by examining their contributions to studies of glioblastoma prevention, tumorigenesis, and chemoresistance.

The p38 signaling pathway mediates quiescence of glioma stem cells by regulating epidermal growth factor receptor trafficking.

EGFR pathway is upregulated in malignant gliomas, and its downstream signaling is important for self-renewal of glioma cancer stem-like cells (GSC). p38 mitogen-activated protein kinase (MAPK) signaling, a stress-activated signaling cascade with suppressive and permissive effects on tumorigenesis, can promote internalization and ubiquitin ligase mediated degradation of EGFR. In this study, we investigated the role of p38 MAPK signaling on the self-renewal of GSCs with the hypothesis that inhibition may lead to enhanced self-renewal capacity by retention of EGFR. Inhibition of p38 MAPK pathway led to increase in EGFR expression but surprisingly, reduced proliferation. Additional functional evaluation revealed that p38 inhibition was associated with decrease in cell death and maintenance of undifferentiated state. Further probing the effect of p38 inhibition demonstrated attenuation of EGFR downstream signaling activity in spite of prolonged surface expression of the receptor. In vitro observations were confirmed in xenograft in vivo experiments. These data suggest that p38 MAPK control of EGFR signaling activity may alter GSC cell cycle state by regulating quiescence and passage into transit amplifying state.

The evidence of glioblastoma heterogeneity.

Cancers are composed of heterogeneous combinations of cells that exhibit distinct phenotypic characteristics and proliferative potentials. Because most cancers have a clonal origin, cancer stem cells (CSCs) must generate phenotypically diverse progenies including mature CSCs that can self-renew indefinitely and differentiated cancer cells that possess limited proliferative potential. However, no convincing evidence exists to suggest that only single CSCs are representative of patients' tumors. To investigate the CSCs' diversity, we established 4 subclones from a glioblastoma patient. These subclones were subsequently propagated and analyzed. The morphology, the self-renewal and proliferative capacities of the subclones differed. Fluorescence-activated cell sorting and cDNA-microarray analyses revealed that each subclone was composed of distinct populations of cells. Moreover, the sensitivities of the subclones to an inhibitor of epidermal growth factor receptor were dissimilar. In a mouse model featuring xenografts of the subclones, the progression and invasion of tumors and animal survival were also different. Here, we present clear evidence that a brain tumor contains heterogeneous subclones that exhibit dissimilar morphologies and self-renewal and proliferative capacities. Our results suggest that single cell-derived subclones from a patient can produce phenotypically heterogeneous self-renewing progenies in both in vitro and in vivo settings.

Identification of HLA-A2- and A24-restricted T-cell epitopes derived from SOX6 expressed in glioma stem cells for immunotherapy.

Malignant gliomas are the most aggressive human primary brain tumors and are currently incurable. Immunotherapies have the potential to target glioma and glioma stem cells (GSCs) that are resistant to conventional therapies. We previously identified SOX6 as a human glioma antigen and demonstrated that vaccination with SOX6 DNA induced cytotoxic T lymphocytes (CTLs) specific for glioma, thereby exerting therapeutic antitumor responses in glioma-bearing mice. In this study, we attempted to identify SOX6-derived peptides as specific targets for effective and safe T-cell-mediated immunotherapy targeting SOX6-positive glioma and GSCs. In vitro stimulation with human leukocyte antigen (HLA)-A*2402 (A24)-restricted peptides, RFENLGPQL (SOX6(504)) and PYYEEQARL (SOX6(628)) or the HLA-A*0201 (A2)-restricted peptide, ALFGDQDTV (SOX6(447)) was capable of inducing SOX6 peptide-specific CTLs in peripheral blood mononuclear cells derived from healthy donors and glioma patients. These CTLs were able to lyse a majority of glioma cell lines and a GSC line derived from human glioblastoma in an HLA Class I-restricted and an antigen-dependent manner. Furthermore, peptide vaccines of SOX6(628), which was conserved in the murine SOX6 protein and expected to bind to major histocompatibility complex (MHC) H-2(d), induced CTLs specific for SOX6(628) in H-2(d) mice. Normal autologous cells from mice, in which SOX6-specific immune responses were generated, were not destroyed. These results suggest that these SOX6 peptides are potnetially immunogenic in HLA-A24 or -A2 positive glioma patients and should be considered as a promising strategy for safe and effective T-cell-based immunotherapy of patients with gliomas.

Brain tumor stem cells from an adenoid glioblastoma multiforme.

Brain tumors may arise from and contain cancer stem cells (CSCs) capable of self-renewal, proliferation, and differentiation that recapitulate the parent tumor. These CSCs are thought to be important in gliomagenesis. Detection of CSCs invading the adjacent brain regions is important for the diagnosis and effective treatment of glioblastoma multiforme (GBM). A 57-year-old man presented with an adenoid GBM, and underwent resection of the tumor. Multipotent, self-renewing cells derived from the human adenoid GBM were isolated and identified with the tumor-derived stem cell surface antigen CD133 from whole autopsied patient's brain. Tumorsphere culture and flow cytometric analysis revealed that 1.02-2.32% of the cells were positive for CD133. Transplantation of cultured tumorspheres into the mice brain resulted in the formation of well-defined tumor masses after 12 weeks. The histological and immunohistochemical characteristics of the xenograft were identical to those of the parent tumor. Examination of the patient's brain at autopsy showed CD133-positive cells were identified in the brain regions adjacent to the tumor, suggesting that CD133-positive CSCs might be localized to the vascular niche. Methods to localize CSCs may open new approaches for the treatment of brain tumors.

Epidermal growth factor plays a crucial role in mitogenic regulation of human brain tumor stem cells.

A cancer stem cell population in malignant brain tumors takes an essential part in brain tumor initiation, growth, and recurrence. Growth factors, such as epidermal growth factor, fibroblast growth factor-2, vascular endothelial growth factor, platelet-derived growth factor, and hepatocyte growth factor, are shown to support the proliferation of neural stem cells and also may play key roles in gliomagenesis. However, the responsible growth factor(s), which controls maintenance of brain tumor stem cells, is not yet uncovered. We have established three cancer stem cell lines from human gliomas. These cells were immunoreactive with the neuronal progenitor markers, nestin and CD133, and established tumors that closely resembled the features of original tumor upon transplantation into mouse brain. Three cell lines retained their self-renewal ability and proliferation only in the presence of epidermal growth factor (>2.5 ng/ml). In sharp contrast, other growth factors, including fibroblast growth factor-2, failed to support maintenance of these cells. The tyrosine kinase inhibitors of epidermal growth factor signaling (AG1478 and gefitinib) suppressed the proliferation and self-renewal of these cells. Gefitinib inhibited phosphorylation of epidermal growth factor receptor as well as Akt kinase and extracellular signal-regulated kinase 1/2. Flow cytometric analysis revealed that epidermal growth factor concentration-dependently increased the population of CD133-positive cells. Gefitinib significantly reduced CD133-positive fractions and also induced their apoptosis. These results indicate that maintenance of human brain tumor stem cells absolutely requires epidermal growth factor and that tyrosine kinase inhibitors of epidermal growth factor signaling potentially inhibit proliferation and induce apoptosis of these cells.

Long-term maintenance of brain tumor stem cell properties under at non-adherent and adherent culture conditions.

There is increasing evidence for the presence of cancer stem-like progenitors in malignant brain tumors. This subpopulation of progenitor cells, the so-called "cancer stem cells (CSCs)", may play a pivotal role in brain tumor initiation, growth, and recurrence. Here we describe the establishment of one permanent brain tumor stem cell line that able to form new spheres after culture under adherent monolayer conditions and to recapitulate the properties of the original tumor upon transplantation into immunodeficient mice. Re-formed spheres retained their stem cell properties and isolated single CSCs from these spheres formed spheres/tumors even after long-term cultures (over 2 years). These data suggested that a small population of CSCs preserved its stem cell properties even after serial passages under non-adherent/adherent culture conditions. Evaluation of underlying metabolic events and assessment of the biological features of these viable cell lines will yield useful knowledge on the in situ behavior of brain tumors.

VEGF promotes tumorigenesis and angiogenesis of human glioblastoma stem cells.

There is increasing evidence for the presence of cancer stem cells (CSCs) in malignant brain tumors, and these CSCs may play a pivotal role in tumor initiation, growth, and recurrence. Vascular endothelial growth factor (VEGF) promotes the proliferation of vascular endothelial cells (VECs) and the neurogenesis of neural stem cells. Using CSCs derived from human glioblastomas and a retrovirus expressing VEGF, we examined the effects of VEGF on the properties of CSCs in vitro and in vivo. Although VEGF did not affect the property of CSCs in vitro, the injection of mouse brains with VEGF-expressing CSCs led to the massive expansion of vascular-rich GBM, tumor-associated hemorrhage, and high morbidity, suggesting that VEGF promoted tumorigenesis via angiogenesis. These results revealed that VEGF induced the proliferation of VEC in the vascular-rich tumor environment, the so-called stem cell niche.

Cognitive impairment after traumatic brain injury: a functional magnetic resonance imaging study using the Stroop task.

The anterior cingulate cortex (ACC) plays a key role in cognition, motor function, and emotion processing. However, little is known about how traumatic brain injury (TBI) affects the ACC system. Our purpose was to compare, by functional magnetic resonance imaging (fMRI) studies, the patterns of cortical activation in patients with cognitive impairment after TBI and those of normal subjects. Cortical activation maps of 11 right-handed healthy control subjects and five TBI patients with cognitive impairment were recorded in response to a Stroop task during a block-designed fMRI experiment. Statistical parametric mapping (SPM99) was used for individual subjects and group analysis. In TBI patients and controls, cortical activation, found in similar regions of the frontal, occipital, and parietal lobes, resembled patterns of activation documented in previous neuroimaging studies of the Stroop task in healthy controls. However, the TBI patients showed a relative decrease in ACC activity compared with the controls. Cognitive impairment in TBI patients seems to be associated with alterations in functional cerebral activity, especially less activation of the ACC. These changes are probably the result of destruction of neural networks after diffuse axonal injury and may reflect cortical disinhibition attributable to disconnection or compensation for an inefficient cognitive process.

Endovascular treatment of asymptomatic cerebral aneurysms: anatomic and technical factors related to ischemic events and coil stabilization.

The present study assessed the safety and efficacy of embolization using Guglielmi detachable coils (GDCs) in 100 asymptomatic cerebral aneurysms classified as sidewall (70) or terminal (30) aneurysms according to the parent artery (68 small aneurysms with a small neck, 21 small aneurysms with a wide neck, and 11 large aneurysms). A balloon-assisted technique was used in 49 aneurysms. Immediate angiography revealed that 71 aneurysms were completely obliterated. Transient deficits occurred in 19 patients, permanent deficits in four patients, and one patient died. Most complications occurred during or immediately after treatment and resolved within a few minutes to a few weeks. None of the surviving patients manifested significant morbidity at 1-year follow up. Follow-up angiographic study was performed in 79 aneurysms. Rates of recanalization and progressive thrombosis (total occlusion of the residual aneurysm at follow up) were 11% and 38%, respectively, in sidewall aneurysms, and 26% and 0%, respectively, in terminal aneurysms. Treatment with GDCs was effective for patients with small aneurysms with small necks, the morbidity was acceptable, and progressive thrombosis occurred during the follow-up period. GDC treatment achieved unsatisfactory results in patients with small terminal aneurysms with wide necks and in large aneurysms, because the obliteration rate was low, and the recanalization and complication rates were high. Multivariate analysis showed that complete occlusion was associated with small-necked aneurysms, and ischemic events tended to occur in terminal aneurysms and in aneurysms treated by the balloon-assisted technique.

Thromboembolic events associated with Guglielmi detachable coil embolization with use of diffusion-weighted MR imaging. Part II. Detection of the microemboli proximal to cerebral aneurysm.

BACKGROUND AND PURPOSE: The purpose of this study was to document the incidence and radiologic appearance of thromboembolic events during Guglielmi detachable coil (GDC) embolization for asymptomatic basilar artery (BA) bifurcation and BA-superior cerebellar artery (SCA) aneurysms by using diffusion-weighted (DW) MR imaging, with special emphasis on the evidence of thromboembolic events in vascular territories proximal from the treated aneurysm, which cause cerebellar infarction, and to discuss which step of the procedure (aneurysm or catheter manipulation) may play a role for most thromboembolic events. METHODS: Since 1999, 38 asymptomatic BA bifurcation and BA-SCA aneurysms were treated with GDCs at the National Cardiovascular Center. DW studies were performed for 26 patients between 2 and 5 days after GDC embolizations. All DW images were reviewed by two radiologists for depiction of abnormalities. These findings were retrospectively evaluated with clinical and technical factors of thromboembolic events. RESULTS: DW images showed new hyperintense lesions in 18 patients (69%), with seven (27%) incurring neurologic deteriorations. All symptomatic patients fully recovered by discharge. Fourteen (78%) of 18 patients showed new lesions proximal to the treated aneurysm; that is, in the cerebellar hemispheres. In three cases treated with the balloon-assisted technique, new hyperintense lesions were seen. CONCLUSION: In our experience, most thromboembolic events related to the use of the GDC embolization may be caused by catheter manipulation, especially in the case of the balloon-assisted technique. Caution should be exercised in the handling of catheters. Furthermore, a softer and smaller caliber catheter and simple GDC technique should be considered.

[Management strategy for infectious cerebral aneurysms: report of four cases].

The surgical and/or endovascular treatment of four patients with infectious cerebral aneurysm associated with infective endocarditis was reported. Two patients presented with intracerebral hemorrhage. One of them, with large hematoma, was treated surgically and the other, with small hematoma, was treated by endovascular surgery. The third patient, with unruptured aneurysm of the distal anterior cerebral artery, was treated by endovascular parent-artery occlusion without neurological deterioration. The fourth patient, with unruptured aneurysm of the distal middle cerebral artery, was initially treated with antibiotics, resulting in stabilization of the aneurysm. However, three weeks after open heart surgery, the aneurysm ruptured, causing a large cerebral hematoma. Despite prompt evacuation of the hematoma and surgical resection of the aneurysm, this patient remained in a vegetative state. Management strategy of intracranial infective aneurysms is discussed.

Continued growth of and increased symptoms from a thrombosed giant aneurysm of the vertebral artery after complete endovascular occlusion and trapping: the role of vasa vasorum. Case report.

A 58-year-old woman harboring a partially thrombosed giant aneurysm of the vertebral artery (VA) presented with lower cranial nerve palsies and cerebellar ataxia. The authors initially attempted to reduce the mass effect by obliterating the lumen of the aneurysm as well as by trapping of the parent artery with coils. Although there was no angiographically demonstrated evidence of filling, the aneurysm continued to enlarge. Magnetic resonance imaging revealed a marked enhancement around the packed coils close to the neck of the aneurysm. Aneurysmectomy and removal of the coils were performed and resulted in an almost complete cure of the patient's symptoms. Interestingly, at the time of resection, a marked development of vasa vasorum on the occluded VA and the neck of the aneurysm was noted. When the occluded VA was cut, there was blood oozing through the coils packed within its lumen on the side where the aneurysm lay. Histological examination showed the presence of inflammatory cells and neovascularization of a partially organized thrombus around the packed coils in both the aneurysm and occluded VA. The proliferation of vasa vasorum was also recognized histologically. This unique case provides insight into the growth mechanisms of a partially thrombosed giant aneurysm after an apparently complete occlusion by endovascular treatment, especially the role of vaso vasorum on the occluded parent artery in the dynamic process of neovascularization in the incomplete organization of thrombus around the packed coils.

Cobb syndrome in an infant: treatment with endovascular embolization and corticosteroid therapy: case report.

OBJECTIVE AND IMPORTANCE: Cobb syndrome is a rare clinical entity characterized by the combination of a vascular skin nevus and an angioma in the spinal canal at the same metamere. We present a case report of an infant with Cobb syndrome. CLINICAL PRESENTATION: A 5-month-old girl presented with cutaneous hemangioma of the thoracolumbar region (T5-T12) and paraparesis. The infant was examined by magnetic resonance imaging and aortography and was diagnosed with Cobb syndrome. INTERVENTION: The patient received orally administered prednisolone therapy and underwent endovascular embolization of paravertebral and spinal angiomas with the use of n-butyl-2-cyanoacrylate. Her symptoms improved by combined treatment with liquid embolization and corticosteroid therapy. CONCLUSION: Although Cobb syndrome has been reported in older children, it is extremely rare in infants. To our knowledge, this is the first report of an infant with Cobb syndrome treated with endovascular embolization and corticosteroid therapy. The combined treatment with corticosteroid therapy and endovascular embolization of cutaneomeningospinal angioma in Cobb syndrome seems effective in alleviating symptoms and minimizing morbidity.

Thromboembolic events associated with Guglielmi detachable coil embolization of asymptomatic cerebral aneurysms: evaluation of 66 consecutive cases with use of diffusion-weighted MR imaging.

BACKGROUND AND PURPOSE: Although Guglielmi detachable coil (GDC) endovascular treatment of intracranial aneurysms has become an accepted alternative to surgery, the main complication continues to be thromboembolic events. We sought to determine the frequency and radiologic appearance of thromboembolic events during GDC embolization for asymptomatic cerebral aneurysms by using diffusion-weighted (DW) MR imaging and to determine whether aneurysmal anatomic factors or use of the balloon-assisted technique affected the frequency. METHODS: In 74 patients, 79 asymptomatic cerebral aneurysms were treated with GDC embolizations at the National Cardiovascular Center from 1999 to 2001. Thirty-nine of these aneurysms (49%) were treated with the balloon-assisted technique. DW imaging was performed in 66 patients at 2-5 days after GDC embolization. All DW images were reviewed by two radiologists for depiction of abnormalities. RESULTS: DW images showed hyperintense lesions in 40 patients (61%), with 16 of these patients (40%) incurring neurologic deteriorations. Fifteen of the symptomatic patients (94%) fully recovered by discharge, and the remaining one experienced permanent deficits. Hyperintense lesions were detected more frequently in wide-neck (73%) or large (100%) aneurysms and in procedures that used the balloon-assisted technique (73%) than in small aneurysms (50%) or in procedures with the simple GDC method (49%). The occurrence of new lesions was significantly associated with use of the balloon-assisted technique and with aneurysm diameter in multivariate analysis (P <.05). CONCLUSION: In our experience, thromboembolic events related to the use of GDC embolization are relatively common, especially in wide-neck or large aneurysms or in association with the balloon-assisted technique. Although permanent deficits are rare, the high rate of thromboembolic events suggests that improvements in the technique such as the addition of antiplatelet agents and the development of new embolic materials are mandatory.