Characterization of a GM7 glioblastoma cell line showing CD133 positivity and both cytoplasmic and nuclear localization of nestin.

A newly established GM7 cell line was derived from the tumor tissue of a 65-year-old man surgically treated for a relapse of glioblastoma multiforme that occurred 10 months after first surgery following radiotherapy. GM7 cells exhibit spindle or glia-like morphology, and multinucleated giant cells are also present in the culture. The cells proliferate rapidly (PDT is about 18 h) and tend to grow in multilayer without contact inhibition. Using G-banding and SKY, the GM7 cell line was identified as near-triploid with a large number of structural and numerical abnormalities. Repeated karyotyping during long-term cultivation confirmed a chromosome number of 70+/-3 chromosomes per cell. Special attention was paid to the immunocytochemical analysis of protein markers in this cell line; GM7 cells showed strong positivity for CD133, vimentin, nestin, NF-160 and S-100 protein and weak positivity for GFAP and NSE, but were negative for synaptophysin. The most important features of the GM7 cell line are its stable phenotype CD133+/nestin+, which are accepted as stem cell markers in neural stem/progenitor cells, and especially unusual intracellular localization of the IF protein nestin, which was detected and repeatedly confirmed both in the cytoplasm and cell nucleus. For this reason, the new GM7 glioblastoma cell line represents an important model suitable not only for further studies on glioblastoma biology and cancer stem cells, but particularly for the detailed investigation of the role of nestin in transformed cells.

Screening of genomic imbalances in glioblastoma multiforme using high-resolution comparative genomic hybridization.

Comparative genomic hybridization (CGH) is a molecular cytogenetic technique that allows the genome-wide analysis of DNA sequence copy number differences. We applied conventional CGH and the recently developed high-resolution CGH (HR-CGH) to tumour samples from 18 patients with glioblastoma multiforme (GBM) in order to compare the sensitivity of CGH and HR-CGH in the screening of chromosomal abnormalities. The abnormalities were studied in topologically different central and peripheral tumour parts. A total of 78 different changes were observed using CGH (0-16 per tumour, median 3.5) and 154 using HR-CGH (0-21 per tumour, median 6). Using HR-CGH, losses were more frequent than gains. The representation of the most prominent changes revealed by both methods was similar and was comprised of the amplification of 7q12 and 12q13-q15, the gain of 7, 3q and 19, and the loss of 10, 9p, and 13q. However, HR-CGH detected certain other abnormalities (the loss of 6, 14q, 15q and 18q, and the gain of 19), which were rarely revealed by CGH. Using HR-CGH, the numbers and types of chromosomal changes detected in the central and peripheral parts of GBM were almost the same. The loss of chromosomes 10 and 9p and the gain of chromosomes 7 and 19 were the most frequent chromosomal alterations in both tumour parts. Our results from the GBM analysis show that HR-CGH technology can reveal new, recurrent genetic alterations involving the genes known to participate in tumorigenesis and in the progression of several human malignancies, thus allowing for a more accurate genetic characterization of these tumours.

Nestin expression in the cell lines derived from glioblastoma multiforme.

BACKGROUND: Nestin is a protein belonging to class VI of intermediate filaments that is produced in stem/progenitor cells in the mammalian CNS during development and is consecutively replaced by other intermediate filament proteins (neurofilaments, GFAP). Down-regulated nestin may be re-expressed in the adult organism under certain pathological conditions (brain injury, ischemia, inflammation, neoplastic transformation). Our work focused on a detailed study of the nestin cytoskeleton in cell lines derived from glioblastoma multiforme, because re-expression of nestin together with down-regulation of GFAP has been previously reported in this type of brain tumor. METHODS: Two cell lines were derived from the tumor tissue of patients treated for glioblastoma multiforme. Nestin and other cytoskeletal proteins were visualized using imunocytochemical methods: indirect immunofluorescence and immunogold-labelling. RESULTS: Using epifluorescence and confocal microscopy, we described the morphology of nestin-positive intermediate filaments in glioblastoma cells of both primary cultures and the derived cell lines, as well as the reorganization of nestin during mitosis. Our most important result came through transmission electron microscopy and provided clear evidence that nestin is present in the cell nucleus. CONCLUSION: Detailed information concerning the pattern of the nestin cytoskeleton in glioblastoma cell lines and especially the demonstration of nestin in the nucleus represent an important background for further studies of nestin re-expression in relationship to tumor malignancy and invasive potential.