Biomedical subjects

Burt G Feuerstein

Publications and source records attributed to Burt G Feuerstein.

13 recordsLinked to original sources

PubMed2006

A genetic strategy to overcome the senescence of primary meningioma cell cultures.

Even though meningiomas are the second most common brain tumor in adults, little is known about the molecular basis of their growth and development. The lack of suitable cell culture model systems is an impediment to this understanding. Most studies on meningiomas rely on primary, early passage cell lines that eventually senesce or a few established cell lines that have been derived from aggressive variants of meningiomas. We have isolated three primary meningioma cell lines that are negative for telomerase activity. We can overcome the senescence of a Grade III derived meningioma cell line by expressing the telomerase catalytic subunit (hTERT), whereas Grade I meningioma cell lines require the expression of the human papillomavirus E6 and E7 oncogenes in conjunction with hTERT. Meningioma cell lines, immortalized in this manner, maintain their pre-transfection morphology and form colonies in vitro. We have confirmed the meningothelial origin of these cell lines by assessing expression of vimentin and desmoplakin, characteristic markers for meningiomas. Additionally, we have karyotyped these cell lines using array CGH and shown that they represent a spectrum of the genetic diversity seen in primary meningiomas. Thus, these cell lines represent novel cellular reagents for investigating the molecular oncogenesis of meningiomas.

Biomarkers, Tumor↗

PubMed2006

Chromosome transfer experiments link regions on chromosome 7 to radiation resistance in human glioblastoma multiforme.

Glioblastoma multiforme (GM) is the most lethal form of brain tumor, with a median survival of approximately 1 year. Treatment options are limited. Radiation therapy is a common form of treatment, but many tumors are resistant. In earlier studies, we found that gain of chromosome 7 is associated with radiation resistance in human primary GM. In this study, we extend that result to a model system in which we transferred chromosome 7 to recipient cells and confirmed radiation resistance as a function of chromosome 7 gain. We identified three candidate regions on chromosome 7 that conferred radiation resistance in our model system.

Brain Neoplasms↗

PubMed2006

Molecular subclasses of high-grade glioma predict prognosis, delineate a pattern of disease progression, and resemble stages in neurogenesis.

Previously undescribed prognostic subclasses of high-grade astrocytoma are identified and discovered to resemble stages in neurogenesis. One tumor class displaying neuronal lineage markers shows longer survival, while two tumor classes enriched for neural stem cell markers display equally short survival. Poor prognosis subclasses exhibit markers either of proliferation or of angiogenesis and mesenchyme. Upon recurrence, tumors frequently shift toward the mesenchymal subclass. Chromosomal locations of genes distinguishing tumor subclass parallel DNA copy number differences between subclasses. Functional relevance of tumor subtype molecular signatures is suggested by the ability of cell line signatures to predict neurosphere growth. A robust two-gene prognostic model utilizing PTEN and DLL3 expression suggests that Akt and Notch signaling are hallmarks of poor prognosis versus better prognosis gliomas, respectively.

Biomarkers, Tumor↗

PubMed2005

Molecular cytogenetic analysis of chromosomes 1 and 19 in glioma cell lines.

Deletions of chromosome 1p and 19q arms are frequent genetic abnormalities in primary human gliomas and are especially common in oligodendrogliomas. However, the chromosome 1p and 19q status of many glioma cell lines has not been established. Using homozygosity mapping, fluorescence in situ hybridization (FISH), and comparative genomic hybridization to arrayed BAC (CGHa), we screened 17 glioma cell lines for chromosome 1 and 19 deletions. Sequence tagged site polymorphisms were used to evaluate the cell lines for regions of chromosome 1p and 19q homozygosity. Cell lines A172, U251, TP265, U118, SW1088, U87, SW1783, and D32 contained significant regions of 19q homozygosity. In addition, A172, U87, TP483, D37, U118, MO67, and TP265 contained significant regions of 1p homozygosity. FISH probes localized to 1p36.32 and 19q13.33 as well as CGHa were used to determine which cell lines had deletions of 1p and/or 19q. Cell lines A172, U87, TP483, TP265, H4, U251, and D37 were deleted for portions of 1p. CGHa and homozygosity mapping of these cell lines define a 700-kilobase (Kb) common deletion region that is encompassed by a larger deletion region previously mapped in sporadic gliomas. This common deletion region is localized at 1p36.31 and includes CHD5, a putative tumor suppressor gene. Cell line A172 was observed to have a deletion between 19q13.33 and 19q13.41, while U87 was observed to have a smaller deletion of 19q13.33. Cell lines A172 and U87 contain 1p and 19q deletions similar to those found in sporadic gliomas and will be useful cellular reagents for evaluating the function of putative 1p and 19q glioma tumor suppressor genes.

Cell Line, Tumor↗

PubMed2005

Isochromosome 17q is a negative prognostic factor in poor-risk childhood medulloblastoma patients.

BACKGROUND: Medulloblastomas are the most common primary malignant childhood intracranial neoplasms. Patients are currently sorted into three risk groups based on clinical criteria: standard, poor, and infant (<18 months old). We hypothesized that genetic copy number aberrations (CNA) predict prognosis and would provide improved criteria for predicting outcome. METHODS: DNA from 35 medulloblastoma patients from four Children's Cancer Group trials was analyzed by comparative genomic hybridization to determine CNAs. The genetic alterations were evaluated using statistical and cluster analyses. RESULTS: The most frequent CNAs were gains on 17q, 7, 1q, and 7q and losses on 17p, 10q, X, 16q, and 11q. Amplification at 5p15.1-p15.3 was also detected. Isochromosome 17q (i(17)(q10)) was associated with poor overall survival (P = 0.03) and event-free survival (P = 0.04) independent of poor risk group classification. Age <3 tended to be associated with <3 CNAs (P = 0.06). Unsupervised cluster analysis sorted the study patients into four subgroups based on CNAs. Supervised analysis using the program Significance Analysis of Microarrays (SAM) quantitatively validated those CNAs identified by unsupervised clustering that significantly distinguished among the four subgroups. CONCLUSIONS: Medulloblastomas are genetically heterogeneous and can be categorized into separate genetic subgroups by their CNAs using unsupervised cluster analysis and SAM. i(17)(q10) was a significant independent negative prognostic factor. Infant medulloblastomas may be a distinct genetic subset from those of older patients.

Adolescent↗

PubMed2005

Array comparative genomic hybridization identifies genetic subgroups in grade 4 human astrocytoma.

Alterations of DNA copy number are believed to be important indicators of tumor progression in human astrocytoma. We used an array of bacterial artificial chromosomes to map relative DNA copy number in 50 primary glioblastoma multiforme tumors at approximately 1.4-Mb resolution. We identified 33 candidate sites for amplification and homozygous deletion in these tumors. We identified three major genetic subgroups within these glioblastoma multiforme tumors: tumors with chromosome 7 gain and chromosome 10 loss, tumors with only chromosome 10 loss in the absence of chromosome 7 gain, and tumors without copy number change in chromosomes 7 or 10. The significance of these genetic groups to therapeutics needs further study.

Brain Neoplasms↗

PubMed2005

Integrated array-comparative genomic hybridization and expression array profiles identify clinically relevant molecular subtypes of glioblastoma.

Glioblastoma, the most aggressive primary brain tumor in humans, exhibits a large degree of molecular heterogeneity. Understanding the molecular pathology of a tumor and its linkage to behavior is an important foundation for developing and evaluating approaches to clinical management. Here we integrate array-comparative genomic hybridization and array-based gene expression profiles to identify relationships between DNA copy number aberrations, gene expression alterations, and survival in 34 patients with glioblastoma. Unsupervised clustering on either profile resulted in similar groups of patients, and groups defined by either method were associated with survival. The high concordance between these separate molecular classifications suggested a strong association between alterations on the DNA and RNA levels. We therefore investigated relationships between DNA copy number and gene expression changes. Loss of chromosome 10, a predominant genetic change, was associated not only with changes in the expression of genes located on chromosome 10 but also with genome-wide differences in gene expression. We found that CHI3L1/YKL-40 was significantly associated with both chromosome 10 copy number loss and poorer survival. Immortalized human astrocytes stably transfected with CHI3L1/YKL-40 exhibited changes in gene expression similar to patterns observed in human tumors and conferred radioresistance and increased invasion in vitro. Taken together, the results indicate that integrating DNA and mRNA-based tumor profiles offers the potential for a clinically relevant classification more robust than either method alone and provides a basis for identifying genes important in glioma pathogenesis.

Adipokines↗

PubMed2005

Biphasic calcium response of platelet-derived growth factor stimulated glioblastoma cells is a function of cell confluence.

BACKGROUND: Previous reports have linked the spiking or two-phased character of calcium transients evoked by platelet-derived growth factor (PDGF) to the position of cells in the cell cycle without regard to cell-cell contact and communication. Because cell confluence can regulate growth factor receptor expression and dephosphorylation, we investigated the effect of cell culture confluence and cell cycle on calcium responses of PDGF-BB-stimulated A172 glioblastoma cells. METHODS: Digital imaging cytometry was used to correlate the peak and duration of calcium response with bromodeoxyuridine positivity and DNA content and with culture confluence on a cell-by-cell basis. RESULTS: In serum-starved cultures, complete two-phase calcium signals and shorter, lower spikes occurred independent of cell cycle phase. However, the confluence of cell culture seemed essential for inducing a complete response because cells in sparse cultures exhibited mostly short spikes with lower peaks or no transients at all. CONCLUSION: Because cell confluence, by virtue of cell-cell contacts, is assumed to be an important regulator of proliferation, one is tempted to speculate that in transformed cells the ability to produce stronger growth signals upon reaching confluence and facing contact inhibition could provide a proliferative advantage.

Becaplermin↗

PubMed2005

Chromosomal imbalances detected by array comparative genomic hybridization in human oligodendrogliomas and mixed oligoastrocytomas.

Loss of heterozygosity and fluorescence in situ hybridization (FISH) studies have shown that deletions of 1p and 19q are highly prevalent in oligodendroglioma. However, these tumors have not been comprehensively screened for other alterations in chromosomal dosage. In this study, we used array-based comparative genomic hybridization (CGHa) of mapped BAC DNA to screen for such alterations in 31 oligodendrogliomas (20 grade II, 9 grade III, and 2 grade IV) and 4 mixed oligoastrocytomas (1 grade I, 1 grade II, and 2 grade IV). The most frequent aberrations were loss of 1p (17 cases; 49%) and 19q (15 cases; 43%) and combined loss of 1p/19q (13 cases; 37%). In addition, deletion of 4q, 5p, 9p, 10q, 11p, and 13q was observed in 10, 4, 8, 4, 4, and 13 cases, respectively; loss of whole chromosomes 4, 9, and 13 in 4, 1, and 7 cases, respectively; gain of 7p, 8q, 10p, and 11q in 6, 6, 5, and 10 cases, respectively, and gain of whole chromosomes 7 and 11 in 2 patients each. Minimally altered regions detected by CGHa involved chromosome bands 1p36.32, 4q33, 5p15, 8q24, 11p15, and 19q13.3. Univariate analysis of all 35 cases suggested that combined deletion of 1p and 19q is associated with better survival (P = 0.03). In addition, 8q gain in the oligodendrogliomas was strongly associated with poor outcome (P = 0.002). Also associated with poor disease outcome were alterations that had low prevalence in the pure oligodendrogliomas, including loss of 3q, 9q, and 12q and gain of 1p, 8p, and 10q. In summary, in oligodendrogliomas, CGHa was able to detect novel small alterations in chromosomal dosage that had not been previously detected by other methods. In addition, our findings support the hypotheses that oligodendroglioma can be classified into several groups by CGHa analysis and that specific alterations in genetic dosage may have biologic or clinical significance.

Adult↗

PubMed2004

A complex rearrangement of chromosome 7 in human astrocytoma.

Chromosome 7 is a frequent site of cytogenetic aberrations in human astrocytomas. One region that is often targeted in human astrocytomas is on 7p. The U251 human glioblastoma cell line has a region of gain of genetic material on 7p similar to that seen in human astrocytomas. We used several cytogenetic techniques to study chromosome 7 in U251 cells and identified a complex rearrangement that accounts for gain of chromosome 7 genetic material in the cell line. The characteristic rearrangement suggests a mechanism leading to 7p gain in primary grade IV astrocytomas.

Astrocytoma↗

PubMed2003

Grade II astrocytomas are subgrouped by chromosome aberrations.

Grade II astrocytoma is defined as a low-grade tumor, yet patients have a wide range of survival and tumors can quickly progress to high-grade astrocytoma/glioblastoma. Previous studies using comparative genomic hybridization (CGH) failed to demonstrate frequent copy number aberrations (CNA) in these tumors. This may be related to technical difficulties because infiltrating astrocytic tumors are often intermixed with normal brain tissue. We developed methods to exclude most normal tissue and use small amounts of DNA for CGH by microdissecting small regions of tumor from paraffin sections and amplifying extracted DNA using degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR). Using this method, we examined 30 grade II astrocytoma cases. We found CNA in 25 cases (83%), with a mean of two CNA per case. The most frequent CNA were gains on 7q (12 cases), 5p (5 cases), 9 (5 cases), and 19p (3 cases), and losses on 19q (7 cases), 1p (6 cases), and Xp (3 cases). Gain on 7q and losses on 1p/19q were mutually exclusive. This is the first report on the genetic characterization of low-grade astrocytomas using CGH from microdissected and formalin-fixed tissue. The comparatively large number of cases in this study allows us to suggest that these tumors are genetically subgrouped.

Adolescent↗

PubMed2002

Genetic aberrations defined by comparative genomic hybridization distinguish long-term from typical survivors of glioblastoma.

Glioblastoma (GBM) remains a highly lethal neoplasm, refractory to current therapies. The molecular genetic aberrations most closely related to clinical aggressiveness in GBM have been difficult to identify, perhaps due in part to the short survival range observed in cohorts of GBM patients. To address this, we characterized 39 tumors from rare patients (2-5% of all GBM cases) who experienced long-term survival (>3 years) using comparative genomic hybridization as a genome-wide screen. We then compared the frequency and type of aberrations with those in tumors from 24 typical or short-term survivors [STSs (<1.5 years)]. Losses of 9p and 10 and simple gains of chromosome 7 showed at least trends toward increased frequency in the STS group. Additional aberrations, including loss of 6q and gains of 19q and 20q, were significantly more frequent in the STS group. The presence of 19q loss was exclusive to the long-term survivor (LTS) group. Multivariate analyses indicated that 6q loss, 10q loss, and 19q gain were associated with short-term survival (all P < 0.01). The combination of any two of these three aberrations was seen in 16 of 24 STSs but only 1 of 39 LTSs. This comparison of rare LTSs with STSs (typical GBM survivors) identified 6q loss, 10q loss, and 19q gain, particularly when two or more of these were present, as most closely associated with aggressive clinical behavior in GBM. Loss of 19q may be a marker of long-term survival.

Adolescent↗

PubMed2002

Integrated genomic and epigenomic analyses pinpoint biallelic gene inactivation in tumors.

Aberrant methylation of CpG islands and genomic deletion are two predominant mechanisms of gene inactivation in tumorigenesis, but the extent to which they interact is largely unknown. The lack of an integrated approach to study these mechanisms has limited the understanding of tumor genomes and cancer genes. Restriction landmark genomic scanning (RLGS; ref. 1) is useful for global analysis of aberrant methylation of CpG islands, but has not been amenable to alignment with deletion maps because the identity of most RLGS fragments is unknown. Here, we determined the nucleotide sequence and exact chromosomal position of RLGS fragments throughout the genome using the whole chromosome of origin of the fragments and in silico restriction digestion of the human genome sequence. To study the interaction of these gene-inactivation mechanisms in primary brain tumors, we integrated RLGS-based methylation analysis with high-resolution deletion maps from microarray-based comparative genomic hybridization (array CGH; ref. 3). Certain subsets of gene-associated CpG islands were preferentially affected by convergent methylation and deletion, including genes that exhibit tumor-suppressor activity, such as CISH1 (encoding SOCS1; ref. 4), as well as genes such as COE3 that have been missed by traditional non-integrated approaches. Our results show that most aberrant methylation events are focal and independent of deletions, and the rare convergence of these mechanisms can pinpoint biallelic gene inactivation without the use of positional cloning.

Alleles↗