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Classification of astrocytomas and malignant astrocytomas by principal components analysis and a neural net.

The classification of astrocytomas, astrocytomas with anaplastic foci and glioblastoma multiformes is not always straightforward because the tumors form a histological continuum. The use of principal component analysis (PCA) and neural nets in the classification of these tumors is explored. PCA was performed on 14 histological features recorded from 52 gliomas classified by the Radiation Therapy Oncology Group method (17 astrocytomas, 18 astrocytomas with anaplastic foci, 17 glioblastoma multiformes). Four of the 14 possible 'scores' derived from this analysis were selected to summarize the histological variability seen in all the tumors. These scores were mostly significantly different between tumor types and were thus used to successfully train a neural net to correctly classify these tumors. The first principal component (score) supported the use of increasing cellularity, mitoses, endothelial proliferation, and necrosis in differentiating between the tumor categories, but accounted for only 39% of the variability seen. Other histological features that were significant components of the other scores included the presence of multinucleated or giant cells, gemistocytes, atypical mitoses and changes in nuclear chromatin. Computer programs derived from the methodology described provide a way of standardizing glioma diagnosis and may be extended to assist with management decisions.

Astrocytoma↗

Phase II trial of carmustine, cisplatin, and oral etoposide chemotherapy before radiotherapy for grade 3 astrocytoma (anaplastic astrocytoma): results of North Central Cancer Treatment Group trial 98-72-51.

PURPOSE: To evaluate the efficacy of preradiotherapy (RT) chemotherapy with carmustine, cisplatin, and oral etoposide combined with RT in the treatment of newly diagnosed anaplastic astrocytoma. METHODS AND MATERIALS: Therapy consisted of carmustine (40 mg/m(2)/d) on Days 1-3, oral etoposide (50 mg/d) on Days 1-21 and 29-49, and cisplatin (20 mg/m(2)/d i.v.) on Days 1-3 and 29-31. The regimen was repeated every 8 weeks for three cycles, with conventionally fractionated RT (5000 cGy with a 1000-cGy boost) delivered concurrently with the third cycle. RESULTS: A total of 29 patients were enrolled between December 1999 and March 2001. For varying reasons (e.g., progression, refusal, death, or toxicity), only 48% completed the chemotherapy regimen and 76% completed RT. Grade 3-4 toxicities were observed in 14 patients (48%). The primary study endpoint was the 23-month (700-day) survival, the median survival of patients with anaplastic astrocytoma in a previous North Central Cancer Treatment Group trial. To be considered an active treatment, a maximum of 9 patient deaths (of the first 25) were allowed before 700 days. However, 14 patients had died by 700 days after therapy. CONCLUSION: Our results have demonstrated that pre-RT chemotherapy with this regimen is insufficiently active in patients with anaplastic astrocytoma.

Administration, Oral↗

Infiltrative astrocytomas with granular cell features (granular cell astrocytomas): a study of histopathologic features, grading, and outcome.

Granular cell astrocytomas (GCAs) are rare, incompletely characterized infiltrative gliomas that contain a prominent component of granular cells. Such tumors can readily be mistaken for reactive conditions. We studied 22 cases to explore their morphologic spectrum, establish features useful in distinguishing GCA from nonneoplastic diseases, and to determine which parameters correlate with biologic behavior. Tumors occurred in 17 men and five women, ranging in age from 29 to 75 years, who presented mainly with seizures, headache, aphasia, or hemiparesis. Radiologically, high-grade GCAs were contrast-enhancing, cerebral hemispheric masses with prominent peritumoral edema. All contained sheets or interspersed large, round cells packed with eosinophilic, PAS-positive granules. Lymphocytic infiltrates, either perivascular or admixed with neoplastic cells, were present in 14 tumors. Transition to typical infiltrating astrocytoma was noted in 16 cases; of these, granular cells comprised 30-95% of cells. Six tumors consisted almost entirely of atypical granular cells. By WHO criteria, four GCA were grade 2, seven were grade 3, and 11 were grade 4. Glial fibrillary acidic protein staining was seen in all but one tumor, and the majority were immunoreactive for S-100 protein, KP-1, ubiquitin, and epithelial membrane antigen. Although MIB-1 proliferation indices increased with tumor grade, granular cells accounted for only a minority of immunoreactive cells. Among 18 cases with follow-up, 15 recurred after surgery and resulted in death (mean survival, 7.6 months). Two patients died postoperatively, and one was alive at 51 months. Granular cell astrocytoma is an uncommon morphologic variant that appears to be rapidly progressive and usually fatal.

Adult↗

Astrocytoma with angiomatoid vascular proliferation ("angiomatous astrocytoma").

We report a surgical case of unusual anaplastic astrocytoma which was accompanied by an exuberant proliferation of abnormal blood vessels with features resembling those of capillary telangiectasis or cavernous angioma. The patient was a 39-year-old man, who presented with a generalized convulsive seizure, and neuroradiological examination revealed a tumor in the left frontal lobe. The resected tumor showed the features of an anaplastic astrocytoma, grade 3. The proliferation of abnormal blood vessels with dilated lumina and thin walls was seen throughout the tumor, and in the central area these vessels were densely packed and almost replaced the neoplastic astrocytic tissue. Although these dense vascular aggregates in the central area closely simulated capillary telangiectasis or cavernous angioma, they were considered to be of a reactive nature. The term "angiomatous astrocytoma", which is analogous to angiomatous meningioma, seemed to be the most appropriate for the present tumor.

Adult↗

Serial stereotactic biopsies and CT scan in gliomas: correlative study in 100 astrocytomas, oligo-astrocytomas and oligodendrocytomas.

Histologic features of 100 supra-tentorial astrocytomas, oligodendrogliomas and oligo-astrocytomas obtained from serial stereotactic biopsies were compared with the corresponding CT scans. Topographic comparisons provided by visualization of the biopsy trajectories on post-biopsy CT scans were available in 24 cases. Areas of contrast enhancement and low attenuation were compared with the histologic grade of malignancy, tumor delimitation and structural type. The latter was determined as follows: Type I-solid tumor tissue without significant peripheral isolated tumor cells; Type II-solid tumor tissue associated with peripheral isolated tumor cells; Type III-isolated tumor cells only. There was a strong correlation between areas of contrast enhancement and tumor microvascularity. In addition, contrast enhancement occurred only in the solid tumor tissue component of the neoplasm. This correlation accounted for the relationship observed between CT images and the structural type of glioma. Contrast enhancement was constant in structural type I gliomas, inconstant in structural type II, and absent in structural type III. No correlation was found between malignancy and contrast enhancement. Contrast enhancement occurred in all grades of malignancy but was a constant feature of grade 4 gliomas. The volume of the tumors could not be reliably determined from CT images alone. Areas of low attenuation on contrast CT scans could correspond to either peritumoral edema or to edematous parenchyma infiltrated by isolated tumor cells. Serial stereotactic biopsies combined with calculations based on the CT scan provided a more precise definition of the tumor volume and identification of structural type. Such classification may prove useful in prospective analysis of various modes of therapy.

Adolescent↗

The pilomyxoid astrocytoma and its relationship to pilocytic astrocytoma: report of a case and a critical review of the entity.

Pilomyxoid astrocytoma (PMA) is a rare glioma that shares histopathological similarities with pilocytic astrocytoma (PA). Yet, typical examples of both can be distinguished on clinical and histological grounds. The reported aggressive behavior of PMA provides a rationale for distinguishing this entity from typical PA. We report a 6(1/2) -year-old girl who had suffered poor weight gain, irritability and progressively worsening abnormal eye movements since approximately 2 months of age. Radiographic studies at 6 months of age (age at initial presentation) revealed a large hypothalamic lesion occupying proximal portions of the optic nerves, chiasm and right posterior optic tract. The first biopsy obtained after two chemotherapy regimens was consistent with a diagnosis of PMA. The patient suffered multiple recurrences, and underwent three subsequent surgical procedures. The last two surgical specimens revealed a tumor with histopathological features of PA. She is alive with residual disease 6 years after initial presentation. While earlier studies focused on the similarities between PA and PMA, considering the latter as the "infantile" form of the former, subsequent work outlined their histological and clinical differences. Some even suggested a different cell type, such as the tanycytic cell as the origin for PMA. This report provides evidence in favor of the earlier argument that there is a close relationship between PA and PMA, and presents a rare "maturation" phenomenon, at least from a morphological perspective. More systematic review of such cases will provide a better answer for the origin of PMA, and its relation to PA.

Astrocytoma↗

A malignant astrocytoma in a patient with AIDS: a possible association between astrocytomas and HIV infection.

We describe a malignant astrocytoma in a patient with AIDS confirmed at autopsy. The object of this report is to draw attention to a further example of an unusual tumour associated with HIV infection. This is the tenth case in the world literature and it is possible that this tumour is represented with a higher than expected frequency in this group of the population. This case and others add malignant astrocytoma to the differential diagnosis of an intracranial space occupying lesion in an AIDS patient.

Acquired Immunodeficiency Syndrome↗

Differential expression of ros oncogene in primary human astrocytomas and astrocytoma cell lines.

Overexpression of oncogenes has been associated with the pathogenesis of some human cancers. The ros oncogene, which encodes a putative receptor with tyrosine kinase activity, has been recently shown to be specifically expressed in high levels in human astrocytoma and glioblastoma cell lines. Using transcription mapping analysis, we surveyed 25 primary astrocytomas of all histological grades, including glioblastomas, and failed to demonstrate elevated expression of ros in these tumors. This difference between the cell lines and the primary tumors may be due to dilution of the ros-positive clones by larger populations of ros-negative cells in the primary tumors or to induction of ros oncogene when the tumors are adapted to tissue culture.

Astrocytoma↗

BCNU-sensitivity in parental cells and clones from four freshly resected near-diploid human gliomas: an astrocytoma, an anaplastic astrocytoma and two glioblastomas multiforme.

We compared the BCNU sensitivity of 4 freshly resected tumors (astrocytoma WM, and malignant gliomas MK, MB, and AM) and their clones to their karyology. The majority of primary cells in all 4 tumors had near-diploid chromosome numbers (2n +/-) and all were resistant to concentrations of BCNU exceeding 10 micrograms/ml. Following in vitro cultivation, the cells from tumors WM and MB retained their 2n +/- modal chromosome number with little change in the complexity of the karyotype. In contrast, tumors MK and AM demonstrated a more unstable genome. The modal chromosome number of MK shifted from 45 to 86 and that of tumor AM from 45 to 90. Karyotyping demonstrated additional ploidy changes and new marker chromosomes in both tumors. The colony forming assay (CFA) performed on the in vitro cultivated cells demonstrated little change in the sensitivity to BCNU in tumors WM and MB, while tumors MK and AM exhibited greater than a one log cell kill at 10.0 micrograms/ml and 15.0 micrograms/ml BCNU, respectively. The modal chromosome number and BCNU sensitivity followed a similar pattern in the 30 clones that were isolated; 21 clones with near-diploid and pseudodiploid chromosome numbers were all resistant to BCNU doses at or greater than 10 micrograms/ml. In contrast, 9 clones isolated from the 3 malignant gliomas with 3n +/- and 4n +/- modal chromosome numbers were sensitive to this concentration of BCNU. The karyotypes of the hyperdiploid clones were more complex; they contained 5 or more ploidy changes and/or had marker chromosomes. These studies confirm the association of diploidy and BCNU-resistance in freshly resected malignant gliomas.

Astrocytoma↗

Expression of pituitary tumor transforming gene (PTTG) and its binding protein in human astrocytes and astrocytoma cells: function and regulation of PTTG in U87 astrocytoma cells.

Human securin, pituitary tumor transforming gene (PTTG), is a protooncogene. Here we report expressions of PTTG and its interacting protein, PTTG-binding factor in human astrocytic cells. PTTG expression was higher in malignant cells than in primary astrocytes, whereas PTTG-binding factor was not. Using a xenotransplantable, glioma cell line (U87), we observed that knocking down PTTG mRNA by RNA silencing inhibited serum-induced proliferation by approximately 50%. Furthermore, in U87 cells PTTG expression was up-regulated by promalignant ligands epithelial growth factor (EGF) and TGFalpha, both at the protein and mRNA levels. PTTG induction by EGF receptor (EGFR) ligands could be blocked by the specific EGFR inhibitor, AG1478. Hepatocyte growth factor (HGF) also induced PTTG but to a lesser extent than EGF. Although EGF stimulates HGF secretion in U87 cells, the effect of EGF on PTTG mRNA expression is independent of HGF as neutralizing antibody against HGF failed to abolish EGF-induced up-regulation of PTTG mRNA. PTTG mRNA was unchanged by incubating U87 cells with the promalignant growth factor TGFbeta, apoptosis inducing TNFalpha and ligands for nuclear receptors, such as retinoic acid and retinoid X receptors and peroxisome proliferator-activated receptor-gamma, known for their growth-inhibitory and apoptosis-inducing effects on gliomas. In addition, 17beta-estradiol and Ca2+, known to activate PTTG expression, did not change PTTG mRNA levels in U87 cells. In summary, we show higher PTTG expression in astrocytoma than normal astrocytes and secondly, PTTG is involved in glioma cell growth. Finally, regulation of its expression has glioma-specific features and is selectively regulated by promalignant cytokines including EGFR ligands and HGF.

Apoptosis↗

Ependymal astrocytoma: subependyoma or subependymal glomerate astrocytoma.

The histological study of four cases and one by electron microscopy of subependyomomas allowed us to obtain morphostructural characteristics of ependymocytes and astrocytes. Comparing these findings to those of the present day literature, we propose to name these tumours ependymal astrocytomas.

Adult↗

Tracking the invasiveness of human astrocytoma cells by using green fluorescent protein in an organotypical brain slice model.

OBJECT: Although it is known that malignant astrocytomas infiltrate diffusely into regions of normal brain, it is frequently difficult to identify unequivocally the solitary, invading astrocytoma cell in histopathological preparations or experimental astrocytoma models. The authors describe an experimental system that facilitates the tracking of astrocytoma cells by using nonneoplastic cerebral tissue as the substrate for invasion. METHODS: Cerebral tissue was cut into 1-mm-thick slices and cultured in the upper chamber of a Transwell culture dish on top of a polyester membrane (0.4-mm pore size) that was bathed in medium supplied by the lower chamber. Two astrocytoma cell lines, U-87 MG (U87) and U343 MG-A (U343), were selected because of their differing basal cell motilities in monolayer cultures. The astrocytoma cells were stably transfected with vectors that expressed green fluorescent protein (GFP), either alone or as a fusion protein with the receptor for hyaluronic acid-mediated motility (RHAMM) in either sense or antisense orientations. Stably transfected clones that had high levels of GFP expression were selected using the direct visualization provided by fluorescence microscopy and fluorescence-activated cell-sorter analysis. The GFP-expressing astrocytoma cell clones were implanted into the center of the brain slice and the degree of astrocytoma invasion into brain tissue was measured at different time points by using the optical sectioning provided by the confocal laser microscope. The authors observed that GFP-expressing astrocytoma cells could be readily tracked and followed in this model system. Individual astrocytoma cells that exhibited green fluorescence could be readily identified following their migration through the brain slices. The GFP-labeled U87 astrocytoma cells migrated farther into the brain slice than the U343 astrocytoma cells. The RHAMM-transfected GFP-labeled astrocytoma cells also infiltrated farther than the GFP-labeled astrocytoma cells themselves. The expression of antisense RHAMM virtually abrogated the invasion of the brain slices by both astrocytoma cell lines. CONCLUSIONS: The authors believe that this organotypical culture system may be of considerable utility in studying the process of astrocytoma invasion, not only because it provides a better representation of the extracellular matrix molecules normally encountered by invading astrocytoma cells, but also because the GFP tag enables tracking of highly migratory and invasive astrocytoma cells under direct vision.

Astrocytoma↗

Role of gemistocytes in astrocytoma progression.

The presence of gemistocytes in low-grade astrocytomas is regarded as a sign of poor prognosis because the majority of gemistocytic astrocytomas rapidly progress to anaplastic astrocytoma or glioblastoma. To elucidate the role of gemistocytes in astrocytoma progression, we assessed the fraction of neoplastic gemistocytes, bcl-2 expression, p53 mutations, p53 immunoreactivity (PAb 1801), and proliferative activity (MIB-1) in 40 low-grade astrocytomas (World Health Organization (WHO) Grade II) with histologically proven progression to anaplastic astrocytoma (WHC Grade III) or glioblastoma (WHO Grade IV). Astrocytoma progression took significantly less time in patients with a low-grade astrocytoma containing more than 5% gemistocytes (35 months) than in those with lesions containing less than 5% gemistocytes (64 months; p = 0.038). All 11 astrocytomas with more than 5% gemistocytes contained a p53 mutation, whereas the incidence of p53 mutations in astrocytomas with less than 5% gemistocytes was 61% (p = 0.017). In low-grade astrocytomas the p53 labeling index (LI) of gemistocytes (7.4%) was significantly higher than in all tumor cells (3.2%, p = 0.0014). Gemistocytes showed a significantly higher bcl-2 expression than all tumor cells, with a mean bcl-2 1 of 15.6% versus 2.7% in low-grade astrocytomas (p = 0.0004), 20.9% versus 3.0% in anaplastic astrocytoma (p = 0.002), and 30.2% versus 5.2% in glioblastomas (p = 0.0002). In contrast, gemistocytes showed a significantly lower proliferating activity than the mean of all tumor cells, with a mean MIB-1 LI of 0.5% versus 2.6% in low-grade astrocytomas, 1.5% versus 11.6% in anaplastic astrocytoma, and 1.7% versus 16.6% in glioblastomas (p < 0.0001). These data show that low-grade astrocytomas with a significant fraction of gemistocytes progress more rapidly and typically carry a p53 mutation. The vast majority of gemistocytes are, however, in a nonproliferative state (G0 phase of the cell cycle), which suggests terminal differentiation. Their accumulation within astrocytomas may be due to bcl-2-mediated escape from apoptosis.

Adult↗

Methylation profiles of thirty four promoter-CpG islands and concordant methylation behaviours of sixteen genes that may contribute to carcinogenesis of astrocytoma.

BACKGROUND: Astrocytoma is a common aggressive intracranial tumor and presents a formidable challenge in the clinic. Association of altered DNA methylation patterns of the promoter CpG islands with the expression profile of cancer-related genes, has been found in many human tumors. Therefore, DNA methylation status as such may serve as an epigenetic biomarker for both diagnosis and prognosis of human tumors, including astrocytoma. METHODS: We used the methylation specific PCR in conjunction with sequencing verification to establish the methylation profile of the promoter CpG island of thirty four genes in astrocytoma tissues from fifty three patients (The WHO grading: I: 14, II: 15, III: 12 and IV: 12 cases, respectively). In addition, compatible tissues (normal tissues distant from lesion) from three non-astrocytoma patients were included as the control. RESULTS: Seventeen genes (ABL, APC, APAF1, BRCA1, CSPG2, DAPK1, hMLH1, LKB1, PTEN, p14ARF, p15INK4b, p27KIP1, p57KIP2, RASSF1C, RB1, SURVIVIN, and VHL) displayed a uniformly unmethylated pattern in all the astrocytoma and non-astrocytoma tissues examined. However, the MAGEA1 gene that was inactivated and hypermethylated in non-astrocytoma tissues, was partially demethylated in 24.5% of the astrocytoma tissues (co-existence of the hypermethylated and demethylated alleles). Of the astrocytoma associated hypermethylated genes, the methylation pattern of the CDH13, cyclin a1, DBCCR1, EPO, MYOD1, and p16INK4a genes changed in no more than 5.66% (3/53) of astrocytoma tissues compared to non-astrocytoma controls, while the RASSF1A, p73, AR, MGMT, CDH1, OCT6, MT1A, WT1, and IRF7 genes were more frequently hypermethylated in 69.8%, 47.2%, 41.5%, 35.8%, 32%, 30.2%, 30.2%, 30.2% and 26.4% of astrocytoma tissues, respectively. Demethylation mediated inducible expression of the CDH13, MAGEA1, MGMT, p73 and RASSF1A genes was established in an astrocytoma cell line (U251), demonstrating that expression of these genes is likely regulated by DNA methylation. AR gene hypermethylation was found exclusively in female patients (22/27, 81%, 0/26, 0%, P < 0.001), while the IRF7 gene hypermethylation preferentially occurred in the male counterparts (11/26, 42.3% to 3/27, 11%, P < 0.05). Applying the mathematic method "the Discovery of Association Rules", we have identified groups consisting of up to three genes that more likely display the altered methylation patterns in concert in astrocytoma. CONCLUSIONS: Of the thirty four genes examined, sixteen genes exhibited astrocytoma associated changes in the methylation profile. In addition to the possible pathological significance, the established concordant methylation profiles of the subsets consisting of two to three target genes may provide useful clues to the development of the useful prognostic as well as diagnostic assays for astrocytoma.

Adolescent↗

Expression of the small heat shock protein (hsp) 27 in human astrocytomas correlates with histologic grades and tumor growth fractions.

1. Cellular expression and distribution of the stress response small heat shock protein 27 (hsp27) in 39 high-grade astrocytomas (27 glioblastoma multiformes, 12 anaplastic astrocytomas) and in 27 low-grade astrocytomas (grade I-II) were analyzed immunohistochemically. 2. The correlation between hsp27 expression and tumor growth fractions of the astrocytomas was examined following Ki-67 immunostaining. 3. The hsp27 staining was cell cytoplasmic. The hsp27 immunopositive rate was significantly higher in high-grade astrocytomas; the rates was 74% for glioblastomas, 58% for anaplastic astrocytomas, and 37% for low-grade astrocytomas. The small and large tumor cells, especially in glioblastomas, multinucleated tumor giant cells, tumor cells in the pseudopalisading and necrotic areas, cells of the microvascular endothelial proliferations, and tumor vascular smooth muscles were usually hsp27 positive. The mean percentage of hsp27-positive cells was significantly higher in the glioblastomas alone and in the combined high-grade astrocytomas, compared to the low-grade, and in recurrent rather than in primary high-grade astrocytomas. 4. The high-grade astrocytomas had a highly statistical significant Ki-67 labeling index. The Ki-67 labeling indices were significantly higher in the hsp27-positive than the hsp27-negative astrocytomas, irrespective of the histological grade. In the high-grade astrocytomas with a Ki-67 labeling index of five and above, 81% of those tumors were hsp27 positive. 5. Thus, a large number of human astrocytomas express hsp27, and hsp27 expression correlates with histological grades of astrocytoma and with tumor growth fractions. This being the case, hsp27 is likely to have a role in the growth of human astrocytomas.

Adolescent↗

Differential expression between pilocytic and anaplastic astrocytomas: identification of apolipoprotein D as a marker for low-grade, non-infiltrating primary CNS neoplasms.

Fibrillary astrocytoma, the most common primary central nervous system neoplasm, is infiltrating, rapidly proliferating, and almost invariably fatal. This contrasts with the biologically distinct pilocytic astrocytoma, which is circumscribed, often cystic, slowly proliferating, and associated with a favorable long-term outcome. Diagnostic markers for distinguishing pilocytic astrocytomas from infiltrating anaplastic astrocytomas are currently not available. To identify genes that might either serve as markers or explain these distinct biologic behaviors, cDNA microarray analysis was used to compare the expression of 7,073 genes (nearly one quarter of the human genome) between these 2 types of astrocytoma. Messenger RNAs pooled from 3 pilocytic astrocytomas and from 4 infiltrating anaplastic astrocytomas were compared. Apolipoprotein D (apoD), which expressed 8.5-fold higher in pilocytic astrocytomas, showed the greatest level of differential expression and emerged as a potential marker for pilocytic tumors. By immunohistochemistry, 10 of 13 pilocytic astrocytomas stained positively for apoD, while none of 21 infiltrating astrocytomas showed similar staining. ApoD immunostaining was also seen in 9 of 14 of gangliogliomas, 4 of 5 subependymal giant cell astrocytomas (SEGAs), and a single pleomorphic xanthoastrocytomas (PXAs). By in situ hybridization, pilocytic astrocytomas, in contrast with infiltrating astrocytomas, showed widespread increased apoD expression. SAGE analysis using the NCBI database showed a higher level of expression of apoD RNA in pilocytic astrocytoma than in any of the other 94 neoplastic and non-neoplastic tissues in the database. ApoD is associated with decreased proliferation in some cell lines, and is the protein found in highest concentration in cyst fluid from benign cystic disease of the breast. ApoD might play a role in either decreased proliferation or cyst formation in pilocytic astrocytomas, gangliogliomas, SEGAs, and PXAs.

Apolipoproteins↗