The correlation of neoplastic vulnerability with central neuroepithelial cytogeny and glioma differentiation

Osteopontin expression in intratumoral astrocytes marks tumor progression in gliomas induced by prenatal exposure to N-ethyl-N-nitrosourea

To better study early events in glioma genesis, markers that reliably denote landmarks in glioma development are needed. In the present study, we used microarray analysis to compare the gene expression patterns of magnetic resonance imaging (MRI)-localized N-ethyl-N-nitrosourea (ENU)-induced tumors in rat brains with those of uninvolved contralateral side and normal brains. Our analysis identified osteopontin (OPN) as the most up-regulated gene in glioma. Using immunohistochemistry we then confirmed OPN expression in every tumor examined (n = 17), including those with diameters as small as 300 mum. By contrast, no OPN immunostaining was seen in normal brain or in brains removed from ENU-exposed rats before the development of glioma. Further studies confirmed that OPN was co-localized exclusively in intratumoral glial fibrillary acidic protein-expressing cells and was notably absent from nestin-expressing ones. In conjunction with this, we confirmed that both normal neurosphere cells and ENU-im-mortalized subventricular zone/striatal cells produced negligible amounts of OPN compared to the established rat glioma cell line C6. Furthermore, inducing OPN expression in an immortalized cell line increased cell proliferation. Based on these findings, we conclude that OPN overexpression in ENU-induced gliomas occurs within a specific subset of intratumoral glial fibrillary acidic protein-positive cells and becomes evident at the stage of tumor progression.

Lucien J. Rubinstein: enduring contributions to neuro-oncology

Dr. Lucien Rubinstein is best remembered for his significant contributions to the field of neuropathology, particularly in the classification of nervous system tumors. His accomplishments in basic neuro-oncology and in the formulation of diagnostic principles reflected a unique talent for synthesizing fundamental clinicopathological concepts based on skillful diagnostic investigation and a thorough understanding of neurobiology. Dr. Rubinstein was the leader in the establishment of cell cultures from central nervous system (CNS) tumors. He meticulously analyzed both light and electron microscopic features of CNS tumors, recorded his findings, and patiently drew sketches to be shared generously with his colleagues and students. As a pioneer in neuropathology, in his work Dr. Rubinstein set the foundation for many enduring concepts in neurosurgery, neuro-oncology, neurology, and basic tumor biology.

Usefulness of positron emission tomography in diagnosis and treatment follow-up of brain tumors

Clinical and experimental use of positron emission tomography (PET) is expanding and allows quantitative assessment of brain tumor's pathophysiology and biochemistry. PET therefore provides different biochemical and molecular information about primary brain tumors when compared to histological methods or neuroradiological studies. Common clinical indications for PET contain primary brain tumor diagnosis and identification of the metabolically most active brain tumor reactions (differentiation of viable tumor tissue from necrosis), prediction of treatment response by measurement of tumor perfusion, or ischemia. The interesting key question remains not only whether the magnitude of biochemical alterations demonstrated by PET reveals prognostic value with respect to survival, but also whether it identifies early disease and differentiates benign from malignant lesions. Moreover, an early identification of treatment success or failure by PET could significantly influence patient management by providing more objective decision criteria for evaluation of specific therapeutic strategies. Specially, as PET represents a novel technology for molecular imaging assays of metabolism and signal transduction to gene expression, reporter gene assays are used to trace the location and temporal level of expression of therapeutic and endogenous genes. PET probes and drugs are being developed together as molecular probes to image the function of targets without disturbing them and in mass amounts to modify the target's function as a drug. Molecular imaging by PET helps to close the gap between in vitro to in vivo integrative biology of disease.

Medical risk factors and the development of brain tumors

Several diseases and medical treatments are discussed as risk factors for the development of brain tumors. A population-based case-control study in the Rhein-Neckar-Odenwald area (containing 1.3 million inhabitants) of Germany was established to investigate this question. A total of 226 patients (cases) with primary brain tumors (International Classification of Diseases, ninth edition, classes 191, 191.1, and 192.0) and 418 control subjects (controls) were interviewed using a standardized questionnaire over a period of 2 years. No association was seen for head injuries, hereditary diseases, family history, and radiographic examination of the head and teeth. However, more cases than controls had had meningitis (relative risk [RR], 2.7; 95% confidence interval [CI], 0.9 to 8.6) or epilepsy (RR, 2.6; 95% CI, 0.6 to 11.7). The RR was decreased for those who had allergic diseases (RR, 0.7; 95% CI, 0.5 to 1.0), diabetes (RR, 0.7; 95% CI, 0.3 to 1.8), and infections and colds (RR, 0.3; 95% CI, 0.1 to 0.8).

Brain tumors of childhood: nosological and diagnostic problems

Brain tumors containing undifferentiated cells were selected from a series of 504 childhood brain tumors; 117 were analyzed. Most tumors were medulloblastomas, followed by cerebral neuroblastomas, pineocytomas-blastomas, ependymoblastomas, and polar spongioblastomas. Of each oncotype, the main histological features were evaluated, including differentiation and the most important prognostic factors. The terminology and different tumor entities are discussed in light of the recent PNET system. The usefulness of its application is evaluated in relation to prognosis.

The astroblastoma and its possible cytogenic relationship to the tanycyte. An electron microscopic, immunohistochemical, tissue- and organ-culture study

Two examples of cerebral astroblastoma have been studied by electron microscopy and immunohistochemistry, one of them having been maintained in vitro in an organ-culture matrix system for 8 months and the explants studied by light and electron microscopy at different time intervals. The fine structural characteristics were those of a glial cell type with features intermediary between those of astrocytes and ependymocytes. They recapitulated the structure of the tanycyte, a glial precursor cell which is normally found scattered along the ependymal lining of the embryonal and neonatal mammalian brain, but is distinct from epithelial ependymocytes. The possible origin of some astroblastomas from such a cell would account for a number of characteristics in this enigmatic type of glioma.

Immunohistochemical and ultrastructural observations on Homer Wright (neuroblastic) rosettes and the "pale islands" of human cerebellar medulloblastomas

A combined immunohistochemical and ultrastructural study of 20 cerebellar medulloblastomas has demonstrated features of early neuronal differentiation. The differentiation features are primarily encountered in the Homer Wright rosettes and in the reticulin-free "pale islands," or "follicles," of the desmoplastic variant. They consist of parallel arrays of aggregated neurite-like processes containing longitudinally oriented microtubules (immunoreactive for polyvalent antisera to tubulin and gamma-enolase, but nonreactive for a monoclonal antibody to the 150/200 kD subunits of neurofilament protein) and junctional adhesion plaques. We consider the inherent property of self-aggregation of the neurite-like processes with adhesion plaques a significant mechanism in the formation of Homer Wright rosettes. Further differentiation and elongation of these cell processes may lead to the formation of "pale islands" in the desmoplastic medulloblastoma. A meshwork of astroglial cells, coexpressing glial fibrillary acidic protein and S-100 protein immunoreactivity, forms an integral part of the "pale island." The histogenetic significance of these astrocytes and their relationship to tumor cells expressing early neuronal differentiation remains to be defined.