Jörg-Christian Tonn

Cell-extracellular matrix interaction in glioma invasion.

 The complex receptor-ECM interaction in glioma cell invasion is discussed focussing upon the role of integrin receptors and matrix-metalloproteinases. Influencing these molecules or their regulation may lead to novel therapeutic approaches in the treatment of malignant glioma.

Extraneural metastases of primary brain tumors.

Extraneural metastasis (ENM) of primary brain tumors is a rare occurence. Based on a critical analysis of the literature the present review focuses on illustrating special common features of these tumors with regard to immunological, cytokinetical and tumorbiological issues. In this respect much can be learned from the specific conditions following organ transplantation which is extensively discussed.

ECM-MEDIATED GLIOMA CELL INVASION

Cell adhesion receptors of the integrin superfamily, CD44, and adhesion receptors of the immunoglobulin superfamily are expressed by high‐grade astrocytic tumors of the central nervous system. These receptors are critical for the invasion of these tumors in the nervous system. Glioma cells utilize these receptors to adhere to and migrate along the components of the extracellular matrix, which is uniquely distributed and regulated within the brain and the spinal cord. For this reason, glioma cell invasion into the adjacent brain tissue is dependent on the interaction of glioma cells with the extracellular matrix. The receptor‐ECM component interaction is discussed, focusing on the role of cell adhesion molecules of the integrin family and CD44 in glioma cell adhesion and invasion. Microsc. Res. Tech. 43:250–257, 1998.

Glioma cell migration is associated with glioma-induced angiogenesis in vivo.

To simultaneously assess glioma cell invasion and glioma angiogenesis in vivo by non‐invasive and quantitative means, DiI‐labeled C6 glioma spheroids were implanted into the dorsal skinfold chamber preparation of nude mice (n=6). Heat‐inactivated spheroids served as controls to distinguish between active and passive cell spread. Using multi‐flourescent intravital videomicroscopy, glioma cell migration was analyzed on days 1–4, 6, and 10 and spheroid vascularization was analyzed on days 3, 6, and 10 after implantation. Additionaly, C6 glioma spheroids were implanted into the chronic cranial window of nude mice as an orthotopic implantation site (n=4). In the dorsal skinfold chamber, spheroids were vascularized within 10 days and revealed a tumor‐specific microvasculature. In parallel, individual glioma cells detached from the spheroid edge and migrated centrifugally demonstrating an affinity to tumor and host vessels. Glioma cells demonstrated a heterogeneous pattern of their regional migratory actvity (0.2–9.6 μm/h) which correlated well with regional glioma angiogenesis (r=0.733). Using the cranial window, glioma cells spread similarily demonstrating an affinity to the perivascular space of pial/subpial vessels with preference to the arteriolar segments. Intravital fluorescence microscopy represents a versatile technique to assess the complex relationship between glioma‐driven angiogenesis and glioma cell invasion.

Inverse correlation of cell proliferation and expression of progesterone receptors in tumor spheroids and monolayer cultures of human meningiomas.

OBJECTIVE The progesterone receptor (PgR) can be detected in 60 to 70% of meningiomas using immunohistochemistry] in situ. Whereas in monolayer tissue cultures the PgR is only rarely expressed, we were able recently to demonstrate the preservation of the PgR in fragment spheroid cultures of meningiomas. The aim of the present study was to evaluate the stability of PgR expression in meningioma spheroids in vitro and the correlation of PgR expression and cell proliferation in spheroids and whether meningioma cells reaggregated to spheroids from monolayer cultures to reexpress the PgR again. METHODS Tumor fragment spheroids (Weeks 1-6) and cell monolayers (Passages 1 and 3) of 15 PgR-positive meningiomas were investigated by immunohistochemistry for the expression of PgRs and their proliferative activity, as demonstrated by positivity for the proliferation-related antigen Ki-67. To study PgR reexpression in reaggregated spheroids, Northern blots were performed. In addition, a reverse transcriptase-polymerase chain reaction technique was established and evaluated in combination with immunohistochemistry. Growth of meningioma spheroids was quantified in the presence of progesterone and the specific antagonist onapristone. RESULTS The PgR remained stable in spheroids for 6 weeks in 9 of 13 cases that were able to be evaluated. All tumor fragment spheroids exhibited a proliferation index of 5 to 40% Ki-67-positive cells. Monolayer cell cultures, on the other hand, failed to express PgRs but revealed higher proliferation indices (40-90%) to a significant extent. The detection of PgR messenger ribonucleic acid in reaggregated spheroids by means of reverse transcriptase-polymerase chain reaction correlated to the nuclear expression of PgR in immunohistochemistry. Neither progesterone nor its antagonist onapristone altered spheroid growth in vitro. CONCLUSION The expression of the PgR in meningiomas is preserved in spheroid cultures with low proliferation indices for at least 6 weeks, whereas monolayer cell cultures with a high proliferative activity lack PgR expression. The inverse pattern of Ki-67-positive cells in the outer regions of the spheroids and PgR-expressing tumor cells in the spheroid centers leads us to the conclusion that proliferating meningioma tumor cells do not express PgRs. This might also explain why tumor cell growth in vitro was neither affected by progesterone nor by onapristone. Monolayer cell cultures can be reaggregated to spheroids, the consequence being a reexpression of PgRs and, therefore, a down-regulation of proliferation.

Primary Ki-1-positive T-cell lymphoma of the brain—An aggressive subtype of lymphoma: Case report and review of the literature

BACKGROUND By detection of the Ki-1 antigen, Stein (1985) defined a new entity of anaplastic large cell lymphoma [24]. Apart from our case, only four further cases of Ki-1 positive primary central nervous system lymphoma (PCNSL) have been reported in the literature to date. CASE REPORT A 63-year-old man presented with two frontal and parietal mass lesions and one ring lesion on computed tomography scan. Clinically, no evidence of brain metastases or abscesses could be found. Immunohistochemical investigations of biopsy specimens revealed a large cell anaplastic T-cell lymphoma positive to Ki-1 antigen. In spite of all therapeutic efforts, the patient died less than 3 months after the onset of symptoms. DISCUSSION In all cases the clinical course was very rapid, suggesting that Ki-1 positive PCNSL might form an aggressive subtype of lymphomas. Since the radiologic appearance was atypical and clinical diagnosis was not possible, diagnostic biopsy for immunohistochemical diagnosis should be performed.

Human medulloblastomas lack point mutations and homozygous deletions of the hSNF5/INI1 tumour suppressor gene

Medulloblastomas (MBs) are malignant primitive neuroectodermal tumours (PNETs) of the cerebellum occurring predominantly in childhood. The association of monosomy of chromosome 22 with MB is controversial. Atypical teratoid/rhabdoid tumours (AT/RTs) of the brain share clinical and histological features with MBs and supratentorial PNETs (sPNETs). In particular, AT/RTs can be misdiagnosed as MBs and sPNETs because AT/RTs frequently contain areas of primitive neuroepithelial cells similar to PNETs. Recently, mutations of the tumour suppressor gene hSNF5/INI1, located on 22q11.23, have been described in AT/RTs, MBs and sPNETs, with conflicting data on the prevalence of hSNF5/INI1 mutations in the latter entities. Therefore, we screened MBs for point mutations and homozygous deletions of the hSNF5/INI1 tumour suppressor gene. In 90 MBs, no mutations of the hSNF5/INI1 gene were identified. Thus, our study virtually rules out hSNF5/INI1 as a tumour suppressor gene involved in the pathogenesis of medulloblastoma.

Reservoir systems for intraventricular chemotherapy

This paper describes the current techniques for intraventricular drug administration in patients with meningiosis. Advantages and disadvantages of different reservoir systems, the standard implantation procedure and more recently developed image-guided techniques are discussed. In patients with slit ventricles, the CT-based stereotactic approach is recommended for reservoir implantation.

Effect of changes in the CD44 gene on tumour cell invasion in gliomas.

H. Bouterfa, M. Janka, E. Meese, S. Kerkau, K. Roosen & J. C. Tonn (1997) Neuropathology and Applied Neurobiology23, 373–379

Mitoxantrone-induced DNA strand breaks in cell-cultures of malignant human astrocytoma and glioblastoma tumors

In this study mitoxantrone (Mtx) induced DNA strand breaks were measured with the alkaline elution technique in short term cell cultures derived from human gliomas. Glioblastomas or astrocytomasfrom 5 patients who underwent intracranial surgery were cultured and incubated 1 h with different concentrations of Mtx (0, 0.01, 0.1 and 1.0 μg/ml). The alkaline elution methodwas modified to measure DNA lesions in human gliomas. Mtx inducedDNA strand breaks in a dose dependent manner in all cell culturestested. There was a linear increase of DNA strand break frequencyinduced by Mtx between 0.01—1.0 μg/ml. Concerning these in vitro data, Mtx might be potentially useful for the treatment ofpatients with malignant brain tumors.