Eelco W. Hoving

Kinome Profiling in Pediatric Brain Tumors as a New Approach for Target Discovery

Progression in pediatric brain tumor growth is thought to be the net result of signaling through various protein kinase-mediated networks driving cell proliferation. Defining new targets for treatment of human malignancies, without a priori knowledge on aberrant cell signaling activity, remains exceedingly complicated. Here, we introduce kinome profiling using flow-through peptide microarrays as a new concept for target discovery. Comprehensive tyrosine kinase activity profiles were identified in 29 pediatric brain tumors using the PamChip kinome profiling system. Previously reported activity of epidermal growth factor receptor, c-Met, and vascular endothelial growth factor receptor in pediatric brain tumors could be appreciated in our array results. Peptides corresponding with phosphorylation consensus sequences for Src family kinases showed remarkably high levels of phosphorylation compared with normal tissue types. Src activity was confirmed applying Phos-Tag SDS-PAGE. Furthermore, the Src family kinase inhibitors PP1 and dasatinib induced substantial tumor cell death in nine pediatric brain tumor cell lines but not in control cell lines. Thus, this study describes a new high-throughput technique to generate clinically relevant tyrosine kinase activity profiles as has been shown here for pediatric brain tumors. In the era of a rapidly increasing number of small-molecule inhibitors, this approach will enable us to rapidly identify new potential targets in a broad range of human malignancies.

Fetal endoscopic myelomeningocele closure preserves segmental neurological function

Aim  Our aim was to compare the effect of prenatal endoscopic with postnatal myelomeningocele closure (fetally operated spina bifida aperta [fSBA]) versus neonatally operated spina bifida aperta [nSBA]) on segmental neurological leg condition.

TRAIL-receptor expression is an independent prognostic factor for survival in patients with a primary glioblastoma multiforme.

SummaryPurposeIn order to improve the survival of patients with a glioblastoma multiforme tumor (GBM), new therapeutic strategies must be developed. The use of a death inducing ligand such as TRAIL (TNF Related Apoptosis Inducing Ligand) seems a promising innovative therapy. The aim of this study was to quantify the expression of the death regulating receptors TRAIL-R1, TRAIL-R2 and TRAIL on primary GBM specimens and to correlate this expression with survival.Experimental designExpression of TRAIL and TRAIL-receptors was assessed by immunohistochemistry, both quantitatively (% of positive tumor cells) and semi-quantitatively (staining intensity) within both the perinecrotic and intermediate tumor zones of primary GBM specimens. RT-PCR of GBM tissue was performed to show expression of TRAIL receptor mRNA.ResultsImmunohistochemistry showed a slight diffuse intracytoplasmic and a stronger membranous staining for TRAIL and TRAIL receptors in tumor cells. Semi-quantitative expression of TRAIL showed a significantly higher expression of TRAIL in the perinecrotic zone than in the intermediate zone of the tumor (P=0.0001). TRAIL-R2 expression was significantly higher expressed than TRAIL-R1 (P=0.005). The antigenic load of TRAIL-R2 was positively correlated with survival (P=0.02). Multivariate analysis of TRAIL-R1 within the study group (n=62) showed that age, gender, staining intensity, antigenic load, % of TRAIL-R1 expression, were not statistically correlated with survival however radiotherapy was significantly correlated (multivariate analysis: age: P=0.15; gender: P=0.64; staining intensity: P=0.17; antigenic load: P=0.056; % of TRAIL-R1 expression: P=0.058; radiotherapy: P=0.0001). Subgroup analysis of patients who had received radiotherapy (n=47) showed a significant association of % of TRAIL-R1 expression and the antigenic load of TRAIL-R1 with survival (multivariate analysis: P=0.036, respectively, P=0.023).Multivariate analysis of TRAIL-R2 staining intensity and antigenic load, within the study group (P=0.004, respectively, P=0.03) and the subgroup (P=0.002, respectively, P=0.004), showed a significant association with survival. RT-PCR analysis detected a negative relation between the amount of TRAIL-R1 mRNA and the WHO grade of astrocytic tumors (P=0.03).ConclusionsTRAIL-R1 and TRAIL-R2 expression on tumor cells are independent prognostic factors for survival in patients with a glioblastoma multiforme. Both receptors could be targets for TRAIL therapy. As TRAIL-R2 is more expressed, in comparison with TRAIL-R1, on GBM tumor cells, TRAIL-R2 seems to be of more importance as a target for future TRAIL therapy than TRAIL-R1.

The role of diffusion tensor imaging in brain tumor surgery: a review of the literature.

Diffusion tensor imaging (DTI) is a recent technique that utilizes diffusion of water molecules to make assumptions about white matter tract architecture of the brain. Early on, neurosurgeons recognized its potential value in neurosurgical planning, as it is the only technique that offers the possibility for in vivo visualization of white matter tracts. In this review we give an overview of the current advances made with this technique in neurosurgical practice. The effect of brain shift and the limitations of the technique are highlighted, followed by a comprehensive discussion on its objective value. Although there are many limitations and pitfalls associated with this technique, DTI can provide valuable additional diagnostic information to the neurosurgeon. We conclude that current evidence supports a role for DTI in the multimodal navigation during tumor surgery.

Bilateral retinal hemorrhage after endoscopic third ventriculostomy: iatrogenic Terson syndrome

A serious ophthalmological complication of an endoscopic third ventriculostomy that created an iatrogenic Terson syndrome is described. A patient with an obstructive hydrocephalus was treated endoscopically, but due to the inadvertent use of a pressure bag during rinsing, in combination with a blocked outflow channel, a steep rise in intracranial pressure occurred. Postoperatively the patient experienced disturbed vision caused by bilateral retinal hemorrhages, and an iatrogenic Terson syndrome was diagnosed. The pathogenesis of Terson syndrome is discussed based on this illustrative case.

EphB2 activity plays a pivotal role in pediatric medulloblastoma cell adhesion and invasion

Eph/ephrin signaling has been implicated in various types of key cancer-enhancing processes, like migration, proliferation, and angiogenesis. In medulloblastoma, invading tumor cells characteristically lead to early recurrence and a decreased prognosis. Based on kinase-activity profiling data published recently, we hypothesized a key role for the Eph/ephrin signaling system in medulloblastoma invasion. In primary medulloblastoma samples, a significantly higher expression of EphB2 and the ligand ephrin-B1 was observed compared with normal cerebellum. Furthermore, medulloblastoma cell lines showed high expression of EphA2, EphB2, and EphB4. Stimulation of medulloblastoma cells with ephrin-B1 resulted in a marked decrease in in vitro cell adhesion and an increase in the invasion capacity of cells expressing high levels of EphB2. The cell lines that showed an ephrin-B1-induced phenotype possessed increased levels of phosphorylated EphB2 and, to a lesser extent, EphB4 after stimulation. Knockdown of EphB2 expression by short hairpin RNA completely abolished ephrin ligand-induced effects on adhesion and migration. Analysis of signal transduction identified p38, Erk, and mTOR as downstream signaling mediators potentially inducing the ephrin-B1 phenotype. In conclusion, the observed deregulation of Eph/ephrin expression in medulloblastoma enhances the invasive phenotype, suggesting a potential role in local tumor cell invasion and the formation of metastases.

Insights from the supplementary motor area syndrome in balancing movement initiation and inhibition

The supplementary motor area (SMA) syndrome is a characteristic neurosurgical syndrome that can occur after unilateral resection of the SMA. Clinical symptoms may vary from none to a global akinesia, predominantly on the contralateral side, with preserved muscle strength and mutism. A remarkable feature is that these symptoms completely resolve within weeks to months, leaving only a disturbance in alternating bimanual movements. In this review we give an overview of the old and new insights from the SMA syndrome and extrapolate these findings to seemingly unrelated diseases and symptoms such as Parkinson’s disease (PD) and tics. Furthermore, we integrate findings from lesion, stimulation and functional imaging studies to provide insight in the motor function of the SMA.

Desmoplastic infantile ganglioglioma with a malignant course : Case report

Desmoplastic infantile gangliogliomas (DIGs) are rare supratentorial tumors that arise in infancy. Despite the large size of these lesions, the prognosis is generally considered favorable after gross-total resection (GTR); however, in incidental cases tumor progression has been described. The authors report on a child harboring a DIG with a high-grade primitive cell population and glial differentiation. The progressive clinical course was determined by this cell component in spite of GTR and adjuvant chemotherapy. The significance of the presence of a high-grade primitive tumor component in the context of DIG is discussed.

Neonatal high pressure hydrocephalus is associated with elevation of pro-inflammatory cytokines IL-18 and IFNγ in cerebrospinal fluid

BackgroundIn human neonatal high pressure hydrocephalus (HPHC), diffuse white matter injury and gliosis predispose to poor neuro-developmental outcome. The underlying mechanism for diffuse white matter damage in neonatal HPHC is still unclear. Analogous to inflammatory white matter damage after neonatal hypoxemia/ischemia, we hypothesized that pro-inflammatory cytokines could be involved in neonatal HPHC. If so, early anti-inflammatory therapy could ameliorate white matter damage in HPHC, before irreversible apoptosis has occurred. In HPHC and control neonates, we therefore aimed to compare cerebrospinal fluid (CSF) concentrations of IL18, IFNγ and sFasL (interleukin 18, interferon gamma and apoptosis marker soluble-Fas ligand, respectively).MethodsIn neonatal HPHC (n = 30) and controls (n = 15), we compared CSF concentrations of IL18, IFNγ and sFasL using sandwich ELISA. HPHC was grouped according to etiology: spina bifida aperta (n = 20), aqueduct stenosis (n = 4), and fetal intra-cerebral haemorrhage (n = 6). Neonatal control CSF was derived from otherwise healthy neonates (n = 15), who underwent lumbar puncture for exclusion of meningitis.ResultsIn all three HPHC groups, CSF IL18 concentrations were significantly higher than control values, and the fetal intracranial haemorrhage group was significantly higher than SBA group. Similarly, in all HPHC groups CSF-IFNγ concentrations significantly exceeded the control group. In both HPHC and control neonates, CSF FasL concentrations remained within the range of reference values.ConclusionIndependent of the pathogenesis, neonatal HPHC is associated with the activation of the pro-inflammatory cytokines (IL-18 and IFNγ) in the CSF, whereas CSF apoptosis biomarkers (sFasL) were unchanged. This suggests that anti-inflammatory treatment (in addition to shunting) could be helpful to preserve cerebral white matter.

Vascular endothelial growth factor receptor 2 (VEGFR‐2) signalling activity in paediatric pilocytic astrocytoma is restricted to tumour endothelial cells

A. H. Sikkema, E. S. J. M. de Bont, G. Molema, A. Dimberg, P. J. Zwiers, S. H. Diks, E. W. Hoving, W. A. Kamps, M. P. Peppelenbosch and W. F. A. den Dunnen (2011) Neuropathology and Applied Neurobiology37, 538–548