John Provias

Meningiomas: role of vascular endothelial growth factor/vascular permeability factor in angiogenesis and peritumoral edema.

OBJECTIVE Vascular endothelial growth factor (VEGF)/vascular permeability factor (VPF) is a potent angiogenic growth factor implicated in the tumor angiogenesis/metastasis of a number of human cancers. Activation of receptors for VEGF/VPF is specifically mitogenic to endothelial cells and increases their permeability. Although extensive literature exists regarding VEGF/VPF in human astrocytomas, little is known about its potential biological role(s) in meningiomas. Our interest in meningiomas was initiated by the observation that some meningiomas are extremely vascular and are occasionally associated with a considerable degree of peritumoral brain edema, both potentially related to the biological attributes of VEGF/VPF. METHODS As a first test of this hypothesis, we examined a cohort of 18 meningiomas for expression of VEGF/VPF at the messenger ribonucleic acid and protein levels and correlated expression with pathological characteristics, vascularity, and degree of peritumoral edema. RESULTS The majority of meningiomas expressed VEGF/VPF at both the messenger ribonucleic acid and protein levels. Corresponding serial sections were stained with an endothelial cell marker to obtain a microvascular density count, which positively correlated (P = 0.0005) with expression of VEGF/VPF. Furthermore, meningiomas with a large amount of peritumoral edema, as determined from the preoperative computed tomographic scans or magnetic resonance imaging scans, had elevated expression of VEGF/VPF (P = 0.05). CONCLUSION These data suggest that VEGF/VPF may play a role in both meningioma vascularity and peritumoral edema.

Evidence for Altered LRP/RAGE Expression in Alzheimer Lesion Pathogenesis

There is significant evidence to suggest that a damaged or dysfunctional blood-brain barrier (BBB) may contribute to the pathogenesis of Alzheimers disease (AD) lesions. Lipoprotein receptor-related protein (LRP-1) and receptor for advanced glycation end products (RAGE) are known to be important (BBB) capillary transport proteins. Altered expression of either of these capillary endothelial LRP-1 and RAGE receptor proteins could indicate a dysfunction of the BBB and its transport regulation of beta-amyloid (Abeta). Cortical samples from the superior temporal (ST) and calcarine occipital (COC) cortices of ten confirmed AD brains and ten comparison group (CG) brains were examined. The densities of neurofibrillary tangles (NFTs), senile plaques (SPs) and LRP-1 and RAGE positive capillaries were recorded and statistically analyzed. There was a statistically significant difference between AD and CG cases and the densities of LRP-1 and RAGE positive capillaries, the AD cases demonstrating the greater numbers. Further, in AD brains there were significant negative correlations between the Abeta burden of SPs and both LRP-1 and RAGE-positive capillaries [p < .001]. Additionally, there was a strong positive correlation between LRP-1 and RAGE capillaries in AD brains [p < .001]. These results suggest that alterations in the LRP-1 and RAGE mediated transport of Abeta take place in AD brains in lesion prone regions and may therefore contribute to SP lesion pathogenesis.

Cadmium encephalopathy: a report with elemental analysis and pathological findings

We report a boy of East Indian origin, aged 2 years and 10 months, who died suddenly and unexpectedly. Autopsy findings showed marked cerebral swelling with herniation and histological evidence of marked cerebral edema with perivascular protein leakage, indicating blood-brain barrier disruption. Energy dispersive X-ray microprobe analysis of the brain demonstrated the presence of cadmium and a marked increase in sulfur, predominantly intracellular, both within neuroglial, and to a lesser degree endothelial, cells. Localization was predominantly in the nucleus. Analysis of the kidney showed cadmium deposition in renal tubules and in the basal lamina of podocytes within the glomerulus. Although the environmental source of cadmium remains unknown, we speculate that acute cadmium toxicity led to brain intracellular accumulation with resultant cellular dysfunction, blood-brain barrier disruption, and lethal cerebral edema.

The case for blood–brain barrier dysfunction in the pathogenesis of Alzheimer's disease

Alzheimers disease (AD) is a neurodegenerative disease that leads to a progressive loss of integrative and memory capacities of the brain. This is the predominant form of neurodegenerative dementia, with a growing prevalence of between 1 in 50 and 1 in 100 in North America. Numerous hypotheses related to the etiology of AD have developed over the years. However, among the various published hypotheses, the predominant one is related to the progressive and prominent accumulation of central nervous system β‐amyloid peptide and the ensuing brain burden created. It is, therefore, important to consider the homeostatic mechanisms underlying β‐amyloid transport dynamics between the brain and blood vascular compartments. As well, there is a dynamic interrelationship between soluble and insoluble forms of the peptide. Factors that underlie and regulate these dynamic processes are likely relevant to the end accumulation of β‐amyloid peptide in the brain compartment and ultimately in insoluble forms, which is characteristic of, and significant for, the pathophysiology of the Alzheimers brain. Significantly, and in particular relation to the amyloid burden theory mentioned above, it has been postulated that a dysfunctioning blood–brain barrier (BBB) may play a significant, if not critical, role in the pathogenesis of AD. By allowing the influx of injurious materials or agents into the brain or by impeding or blocking the efflux of those materials and/or agents, BBB‐related neuronopathies and their associated sequelae could, and do, ensue.

Significant negative correlations between capillary expressed eNOS and Alzheimer lesion burden

Nitric oxide [NO] is known to have vasoregulatory, neuroprotective and blood-brain barrier (BBB) related transport functions in the human CNS. Altered NO levels are suspected of contributing to neurodegenerative disorders, including Alzheimers disease (AD). NO is produced as a result of the activity of one or more of three isoforms of nitrogen oxide synthase (NOS). In this study we compared Alzheimer and normative comparison brain samples, from temporal and calcarine cortices, with respect to the interactive correlation between eNOS, iNOS and nNOS isoform positive capillaries and the presence of neurofibrillary tangles (NFTs) and senile plaques (SPs). Cortical samples were taken from the superior temporal and calcarine cortices of 10 confirmed AD and 10 non-demented comparison group (CG) brains. Contiguous coronal sections were stained using immunohistochemistry techniques to stain for tau protein, beta amyloid (A beta) n-termini ([40 and 42]), eNOS, iNOS and nNOS. The densities of NFTs, SPs, and eNOS, iNOS and nNOS positive capillaries were recorded. Non-parametric statistical analyses were applied to the data. Our results demonstrate a significant negative correlation between the presence of eNOS positive capillaries and NFTs and SPs in both cortices in AD brains. Our results support the view that eNOS activity should be targeted for further investigation, and that factors involved in the regulation of NO production may be amenable to therapeutic intervention.

A Cancer Stem Cell Model for Studying Brain Metastases From Primary Lung Cancer

BACKGROUND Brain metastases are most common in adults with lung cancer, predicting uniformly poor patient outcome, with a median survival of only months. Despite their frequency and severity, very little is known about tumorigenesis in brain metastases. METHODS We applied previously developed primary solid tumor-initiating cell models to the study of brain metastases from the lung to evaluate the presence of a cancer stem cell population. Patient-derived brain metastases (n = 20) and the NCI-H1915 cell line were cultured as stem-enriching tumorspheres. We used in vitro limiting-dilution and sphere-forming assays, as well as intracranial human-mouse xenograft models. To determine genes overexpressed in brain metastasis tumorspheres, we performed comparative transcriptome analysis. All statistical analyses were two-sided. RESULTS Patient-derived brain metastasis tumorspheres had a mean sphere-forming capacity of 33 spheres/2000 cells (SD = 33.40) and median stem-cell frequency of 1/60 (range = 0-1/141), comparable to that of primary brain tumorspheres (P = .53 and P = .20, respectively). Brain metastases also expressed CD15 and CD133, markers suggestive of a stemlike population. Through intracranial xenotransplantation, brain metastasis tumorspheres were found to recapitulate the original patient tumor heterogeneity. We also identified several genes overexpressed in brain metastasis tumorspheres as statistically significant predictors of poor survival in primary lung cancer. CONCLUSIONS For the first time, we demonstrate the presence of a stemlike population in brain metastases from the lung. We also show that NCI-H1915 tumorspheres could be useful in studying self-renewal and tumor initiation in brain metastases. Our candidate genes may be essential to metastatic stem cell populations, where pathway interference may be able to transform a uniformly fatal disease into a more localized and treatable one.

Bmi1 marks intermediate precursors during differentiation of human brain tumor initiating cells

The master regulatory gene Bmi1 modulates key stem cell properties in neural precursor cells (NPCs), and has been implicated in brain tumorigenesis. We previously identified a population of CD133+ brain tumor cells possessing stem cell properties, known as brain tumor initiating cells (BTICs). Here, we characterize the expression and role of Bmi1 in primary minimally cultured human glioblastoma (GBM) patient isolates in CD133+ and CD133- sorted populations. We find that Bmi1 expression is increased in CD133- cells, and Bmi1 protein and transcript expression are highest during intermediate stages of differentiation as CD133+ BTICs lose their CD133 expression. Furthermore, in vitro stem cell assays and Bmi1 knockdown show that Bmi1 contributes to self-renewal in CD133+ populations, but regulates proliferation and cell fate determination in CD133- populations. Finally, we test if our in vitro stem cell assays and Bmi1 expression in BTIC patient isolates are predictive of clinical outcome for GBM patients. Bmi1 expression profiles show a marked elevation in the proneural GBM subtype, and stem cell frequency as assessed by tumor sphere assays correlates with patient outcome.

An investigation into the role of P-glycoprotein in Alzheimer's disease lesion pathogenesis

The pathogenesis of Alzheimers disease (AD) senile plaque (SP) and neurofibrillary tangle (NFT) lesions putatively involves a compromised blood-brain barrier (BBB). P-glycoprotein (P-gp) is a recognized BBB-related efflux transporter protein. In this investigation we determined the density of SP and NFT lesions and capillary densities stained positively for P-glycoprotein (P-gp), and other transport proteins, in AD and control group (CG) brain samples. Our results indicate that there are significant negative correlations (p<.01) between the densities of NFT and SP(40) lesions and P-gp positive capillaries in AD but not CG brain samples. Significant positive correlations (p<.01) were observed between the densities of P-gp positive capillaries and LRP and RAGE positive capillaries in both AD and CG brains. These results also suggest that the levels of capillary P-gp may contribute to AD lesion development and that the role of P-gp is associated with that of LRP and RAGE.

Congenital Brain Tumors: Diagnostic Pitfalls and Therapeutic Interventions:

Congenital brain tumors are rare, accounting for 0.5% to 4% of all pediatric brain tumors. A 10-year retrospective study based on autopsy and neurosurgical clinical reports with a diagnosis of congenital/fetal/neonatal brain tumor identified 6 cases. Four cases were diagnosed antenatally by neuroradiology. Clinical outcomes in 5 cases resulted in death; 1 patient with choroid plexus papilloma underwent successful resection of the tumor and is still alive. Tumor pathologies consisted of 2 teratomas, 2 choroid plexus papillomas, 1 gemistocytic astrocytoma, and 1 glioblastoma multiforme. A literature review of all fetal cases specific to the pathologies presented in this series was also performed. Relative to the literature, this series contains a rare case of congenital gemistocytic astrocytoma. This series further sheds light on the diagnostic, histological, prognostic, and therapeutic differences between congenital brain tumors and tumors of the same pathology in older pediatric and adult populations.

A heteroplasmic mitochondrial complex I gene mutation in adult-onset dystonia.

Abstract.Mitochondrial DNA (mtDNA) mutations can cause rare forms of dystonia, but the role of mtDNA mutations in other types of dystonia is not well understood. We now report identification by sequencing, restriction endonuclease analyses, and clonal analyses of a heteroplasmic missense A to G base pair substitution at nucleotide position 3796 (A3796G) in the gene encoding the ND1 subunit of mitochondrial complex I in a patient with adult-onset dystonia, spasticity, and core-type myopathy. The mutation converts a highly conserved threonine to an alanine. The same mutation subsequently was identified in 2 of 74 additional unrelated adult-onset dystonia patients. A muscle biopsy was obtained from 1 of these 2 subjects and this revealed abnormalities of electron transport chain (ETC) activities. The mutation was absent in 64 subjects with early onset dystonia, 82 normal controls, and 65 subjects with Parkinsons disease or multiple system atrophy. The A3796G mutation previously has been reported in 3 of 226 subjects from mitochondrial haplogroup H. Each of the 3 subjects in our study harboring the A3796G mutation was also from haplogroup H. However, a subgroup analysis of haplogroup H subjects from our study indicates that the A3796G mutation is significantly overrepresented among haplogroup H adult-onset dystonia subjects compared with haplogroup H controls (P<0.01). This difference remains significant even after excluding the index patient (P=0.04). These data suggest that, among haplogroup H subjects, the presence of the A3796G mutation increases the risk of developing adult-onset dystonia.