Transformation of intracranial anaplastic astrocytoma associated with neurofibromatosis type I into gliosarcoma: Case report

Gliosarcoma is an uncommon malignant brain tumor composed of distinct sarcomatous and malignant glial cell elements. These tumors are defined as a variant of glioblastoma, and it can be developed by progression of the malignant glial cell tumors or primary tumors. We report a rare case with gliosarcomatous recurrence of anaplastic astrocytoma with neurofibromatosis type 1 (NF-1) followed by chemoradiation therapy. A 26-year-old male patient was presented with headache. Five years before admission, he had been diagnosed with NF-1. Magnetic resonance imaging (MRI) showed a well-demarcated, enhanced lesion in the right frontal lobe and multiple enhanced lesions in the scalp, lower cervical, thoracic, and upper lumbar regions. He underwent an osteoplastic craniotomy with total tumor resection. Histopathology of the tumor showed findings corresponding with anaplastic astrocytoma. He was followed by radiotherapy and chemotherapy postoperatively. A month later, his spinal lesion was also resected and confirmed pathologically as plexiform neurofibroma. The subsequent follow-up period of 27 months was uneventful until he developed a generalized tonic-clonic seizure. MRI showed tumor recurrence in the original site of the tumor. Re-exploration was carried out. Pathological examination displayed a biphasic pattern of the glial and sarcomatous components suggesting gliosarcoma.     

Astrocyte-astrocytoma cell line interactions in culture

Astrocytomas are the most common brain tumors arising in the CNS and account for 65% of all primary brain tumors. Astrocytes have been shown to have the highest predisposition to malignant transformation compared to any other CNS cell type. The majority of astrocytomas are histologically malignant neoplasm. Previous studies have shown that resident astrocytes are the first cell type to react to tumors and surround them. However, the role of these astrocytes in tumor formation and progression has not been determined. In the present study, we have co-cultured astrocytes with a permanent cell line S635c15 (derived from anaplastic astrocytoma) in order to understand the cellular interactions between astrocytes and astrocytoma cells. Our studies demonstrate that astrocytes in contact with the tumor cells become reactive and fibrous with an increase in glial fibrillary acidic protein (GFAP) immunoreactivity as early as 4 days in culture. By 8 days, astrocytes formed glial boundaries around the tumor cells which grew as round colonies. The astrocytic processes surrounding the tumor cells were also intensely GFAP positive. Since the behavior of these cells observed in culture is very similar to their interaction seen in vivo, this co-culture system may serve as an in vitro model for astrocyte and astrocytoma cell line interaction and aid in our understanding of the molecular and cellular mechanisms during early stages of tumor formation and cell interactions. © 1996 Wiley-Liss, Inc.     

Pleomorphic xanthoastrocytoma with intraventricular extension and anaplastic transformation in an adult patient: Case report

Pleomorphic xanthoastrocytoma (PXA) is a rare, low-grade astrocytic tumour that usually occurs in the superficial cerebral hemispheres of children and young adults. Although it has a relatively favourable prognosis, malignant progression of these tumours has been described. Therefore, we present an unusual case of a 54-year-old male with a right, multicystic, parietooccipital tumour extending through the ipsilateral ventricle. After surgical resection, histological examination revealed a lesion with pleomorphic cells, cytoplasmic lipidisation, intensely eosinophilic granular bodies, well-delimitated unique nuclei and focal, positive immunoreactivity for synaptophysin, glial fibrillary acidic protein (GFAP), S-100 protein, vimentin and CD56. Once other tumours, such as giant cell metastatic carcinoma or primary lesion like subependymal giant cell astrocytoma, were ruled out, a final diagnosis of XAP was established. After a follow-up period of 9 months, the patient suffered an extensive and local tumour relapse considered inoperable, with progressive neurological deterioration and radiological findings of malignant progression. The brain biopsy procedure revealed anaplastic changes, including necrosis foci, higher mitotic activity (5×10 high-power fields) and a 10% proliferation index measured by Ki67 labelling. The present case showed intraventricular extension and a more aggressive behaviour, both uncommon in these tumours (similar to anaplastic astrocytoma or glioblastoma multiforme), thus demanding an initial, optimal surgical treatment with close clinical and radiological follow-up, due to the high potential for malignant transformation of XAPs.     

Mistaken identity: Granular cell astrocytoma masquerading as histiocytosis of the central nervous system

Granular cell astrocytoma (GCA) is an uncommon malignant glial tumour that is associated with a poor prognosis. GCA cells have some morphological and immunohistochemical similarities to macrophages. In this case, a small biopsy contained no typical astrocytoma and large rounded lesional cells were interpreted as negative for glial fibrillary acidic protein and S100 and positive for CD68, a commonly used marker for macrophages. A diagnosis of a histiocytosis was made. When the patient failed to respond to first and second line therapy, tumour resection was undertaken and the pathology then showed typical morphologic and immunohistochemical features of glioblastoma (astrocytoma World Health Organization grade IV).     

An elderly case of malignant small cell glioma with hemorrhage coexistent with a calcified pilocytic astrocytoma component in the cerebellar hemisphere

Pilocytic astrocytoma is a less aggressive form of glial tumor that commonly occurs in the pediatric population, and its malignant transformation is extremely rare. Here, we report an elderly case of malignant small cell glioma with hemorrhage coexistent with a calcified pilocytic astrocytoma component. An 80‐year‐old male was found to have a right cerebellar non‐enhanced tumor with hematoma adjoining a calcified nodule. The lesion was surgically removed, and a histological examination verified that the tumor was a malignant small cell glioma with hemorrhagic change and the calcified nodule showed features of pilocytic astrocytoma. Genetic analyses revealed no glioma‐relevant genetic alterations such as IDH and BRAF mutations. Although calcification is generally observed in slowly growing gliomas, the aggressive clinical course of calcified cerebellar pilocytic astrocytoma has been previously reported. Our extremely rare case shows that careful follow‐up is necessary even for calcified pilocytic astrocytomas.     

p16(ink4a) and retinoic acid modulate rhoA and GFAP expression during induction of a stellate phenotype in U343 MG-A astrocytoma cells

We previously showed that the expression of p16(ink4a) (p16), in conjunction with retinoic acid (RA) treatment in the p16-deficient astrocytoma cell line, U343 MG-A, induced a potent cell cycle arrest in G(1) associated with changes in morphology. In this study, we investigated the effects of p16 expression and RA treatment on the expression and distribution of actin, glial fibrillary acidic protein (GFAP), and vimentin within the U343 MG-A astrocytoma cytoskeleton. Changes in expression and location of the small GTPase, rhoA, were also examined after p16 expression and RA treatment. We showed that p16 expression and RA treatment led to an increase in the expression of GFAP, as well as its reorganization but that it did not significantly affect actin or vimentin expression. p16 induction in combination with RA treatment resulted in a decreased expression and activation of rhoA as determined by immunocytochemistry and Western blot analysis of soluble and insoluble fractions of cell lysates. Endogenous levels of rhoA expression varied among samples in a panel of astrocytoma cell lines as determined by Western blot analysis. Introduction of a dominant active rhoA mutant into p16-induced, RA-treated U343 MG-A astrocytoma cells was associated with the loss of long astrocytic processes and stellate morphology. These data are among the first to report the pattern of rhoA expression in human astrocytoma cell lines. They furthermore suggest that the stellate cell phenotype observed in U343 MG-A astrocytoma cells after cyclin-dependent kinase inhibitor (CKI) induction and RA treatment is accompanied by an inhibition and inactivation of rhoA in this cell system.     

pRb2/p130 gene overexpression induces astrocyte differentiation

There are many data on the activity of the RB gene in neural differentiation and apoptosis, but the role of pRb2/p130 in neuronal and glial maturation has been far less investigated. To elucidate the role of pRb2/p130 in astrocyte development we overexpressed this protein in astrocytoma and normal astrocyte cultures by adenoviral-mediated gene transfer. In astrocytoma cells, p130/RB2 overexpression resulted in a significant reduction of cell growth and in an increased G(0)/G(1) cell population. We did not observe any induction of programmed cell death as determined by TUNEL reaction. Interestingly, pRb2/p130 overexpression induced astrocyte differentiation. Astrocyte cell cycle arrest and differentiation seemed to proceed through a way distinct from the p53 pathway.     

Glial fibrillary acidic protein in giant cell tumors of brain and other gliomas

Summary The giant cell tumor of brain (glioblastoma/sarcoma) has been considered a glioma by some and a sarcoma by others. This study shows that glial fibrillary acidic protein (GFAP), a specific marker for astrocytes, is present in the tumor cells, thus indicating that the cell of origin is the astrocyte and that the tumor should be called a giant cell glioblastoma. GFAP is present in the smaller cells of this tumor and in larger mononucleated cells, but little if any is detectable in multinucleated giant cells.In a different kind of tumor, the giant cell astrocytoma assonciated with tuberosclerosis, GFAP is restricted in most cells to a narrow peripheral zone.Immunocytochemical localization of GFAP is superior to special stains to differentiate giant cell glioblastomas from true sarcomas and giant cell bone tumors, since the latter are both negative for GFAP.Comparison of GFAP in all tumors of astrocyte origin shows that the cells that appear to contain the most GFAP include low grade well differentiated stellate cells, elongated piloid cells, and gemistocytic astrocytoma cells. Highly malignant undifferentiated cells, with less well developed processes, are less densely positive.Although there is in general an inverse relationship between GFAP content and degree of tumor malignancy, a more complex relationship exists with respect to individual cells; more GFAP is present in well differentiated cells with well-developed processes and filaments than in undifferentiated cells and large multinucleated cells. It is suggested that the pleomorphism of more malignant cells may relate to their relatively low GFAP content and perhaps to the disassembly of their glial filaments.Supported in part by the American Cancer Society, Inc., Grant No. PDT-162     

Emerging roles of p53 in glial cell function in health and disease

Emerging evidence suggests that p53, a tumor suppressor protein primarily involved in cancer biology, coordinates a wide range of novel functions in the CNS including the mediation of pathways underlying neurodegenerative disease pathogenesis. Moreover, an evolving concept in cell and molecular neuroscience is that glial cells are far more fundamental to disease progression than previously thought, which may occur via a noncell-autonomous mechanism that is heavily dependent on p53 activities. As a crucial hub connecting many intracellular control pathways, including cell-cycle control and apoptosis, p53 is ideally placed to coordinate the cellular response to a range of stresses. Although neurodegenerative diseases each display a distinct and diverse molecular pathology, apoptosis is a widespread hallmark feature and the multimodal capacity of the p53 system to orchestrate apoptosis and glial cell behavior highlights p53 as a potential unifying target for therapeutic intervention in neurodegeneration.     

Activation of STAT3, MAPK, and AKT in malignant astrocytic gliomas: correlation with EGFR status, tumor grade, and survival

Diffuse astrocytic gliomas are the most common human glial tumors with glioblastoma being the most malignant form. Epidermal growth factor receptor (EGFR) gene amplification is one of the most common genetic changes in glioblastoma and can lead to the activation of various downstream signaling molecules, including STAT3, MAPK, and AKT. In this study, we investigated the activation status of these 3 signaling molecules as well as wild-type (EGFRwt) and mutant (EGFRvIII) EGFR in 82 malignant astrocytic gliomas (55 glioblastomas and 27 anaplastic astrocytomas) using immunohistochemistry. The presence of EGFRwt, but not EGFRvIII, immunopositivity correlated significantly with prevalent EGFR gene amplification in glioblastomas. STAT3 and AKT activation correlated significantly with EGFR status, although the correlation for p-STAT3 was attributed exclusively to EGFRvIII. The distribution of these 3 activated molecules varied significantly with tumor grade; although activation of STAT3 was essentially identical between anaplastic astrocytomas and glioblastomas, an increase in the activation of MAPK and AKT appeared to correlate with the progression of anaplastic astrocytoma to glioblastoma. Finally, activated STAT3 and AKT were marginally predictive of improved and worse prognosis, respectively. Taken together, these findings begin to elucidate the interrelationship between these signaling pathways in astrocytic gliomas in vivo.     

Localization of basic fibroblast growth factor,a mitogen and angiogenic factor,in human brain tumors

Summary Fibroblast growth factor (FGF) is a potent angiogenic factor and a mitogen for a variety of mesoderm-and neuroectoderm-derived cell types (e.g., fibroblasts, endothelial cells, astrocytes, oligodendrocytes). After application of a monospecific polyclonal antiserum, we localized basic FGF on frozen sections of 73 human brain tumors using immunohisto-chemistry. FGF was present in a variable number of tumor cells (16/16 astrocytomas, 5/5 ependymomas, 0/3 benign and 4/7 anaplastic oligodendrogliomas, 11/12 glioblastomas, 11/11 meningiomas, 6/6 neurilemmomas, 0/3 pituitary adenomas, 2/2 choroid plexus papillomas, 0/1 neurocytoma, 2/2 benign fibrous histiocytomas, 2/5 metastatic carcinomas). FGF was detected in vascular cells of 59 tumors and in fibroblasts of connective tissue stroma from all papillomas and metastases. These results tend to indicate FGF involvement in the malignant progression of gliomas due to an autocrine or paracrine action. Histopathological aspects of malignant gliomas (e.g., pseudopalisading or pathological vessels) could be related to FGF activity.     

Genetic evidence of the neoplastic nature of gemistocytes in astrocytomas

Gemistocytic astrocytoma is characterized by a predominance of large astrocytes with plump processes and massive accumulation of glial fibrillary acidic protein (gemistocytes). This histological variant of low-grade diffuse astrocytoma (WHO grade II) is prone to more rapid progression to anaplastic astrocytoma and glioblastoma than the ordinary fibrillary astrocytoma. The biological basis of this unfavorable prognosis is unclear, since gemistocytes themselves have low proliferative activity, even if present in anaplastic astrocytomas or glioblastomas. This has raised the question of whether gemistocytes are neoplastic cells or dysplastic reactive astrocytes. In this study, gemistocytes and non-gemistocytic neoplastic cells were separated by laser-assisted microdissection from six gemistocytic astrocytomas carrying TP53 mutations. In all cases, identical TP53 mutations were identified in both cell types, indicating that gemistocytes are indeed neoplastic cells. Their lack of proliferative activity may indicate terminal differentiation.     

Co-expression of glial fibrillary acidic protein- and vimentin-type intermediate filaments in human astrocytomas

Summary The expression of intermediate filament (IF) proteins was studied in 71 cases of malignant human astrocytoma and in 17 cases of reactive gliosis, using immunocytochemical techniques with polyclonal and monoclonal antibodies to glial fibrillary acidic protein (GFAP) and vimentin. In all cases of astrocytoma, varying in degree of malignancy from grade I to grade IV, co-expression of GFAP and vimentin was found. No change in vimentin- or GFAP-IF expression with increasing anaplasia was seen. In addition astrocytic cells in reactive gliosis showed simultaneous expression of GFAP and vimentin. The intracellular distribution of these IF proteins differed. Vimentin was found to be located in a more juxta-nuclear position, whereas GFAP immunoreactivity showed a more intense staining of the cellular processes. Astrocytes in reactive gliosis behaved more or less like neoplastic cells. However, thin cell processes of reactive astrocytes in the cortex and superficial white matter only contained GFAP immunoreactivity. Simultaneous expression of GFAP and vimentin and their proportion in malignant and reactive glial cells are discussed in the light of earlier reports on the IF content of glial cells during development and maturation, in which vimentin precedes GFAP-expression. The existence of two separate (functional) IF systems in astroglia is suggested.     

Tumorigenicity of cell lines (VMDk) derived from a spontaneous murine astrocytoma. Histology, fine structure and immunocytochemistry of tumours

Three cell lines (VMDk), derived from a spontaneous murine astrocytoma, which exhibit both morphological and antigenic characteristics of astrocytes in vitro (Pilkington et al. 1983), have been injected intracerebrally and subcutaneously into syngeneic mice at a range of concentrations in order to assess the number of cells required to produce the highest yield of tumours with the shortest possible latent period. Light- and electron-microscopical studies of the tumours confirmed their glial nature, however immunocytochemical staining for the astrocyte-specific markers glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS) and for vimentin suggest that the tumours are composed mainly of poorly-differentiated neoplastic glial cells. Although the best-differentiated of the three cell lines failed to produce tumours, an invasive transplantable astrocytoma model has, nevertheless, been characterised fully and can now be used to study the effects of various therapeutic regimens.     

星形细胞瘤中bFGF和p53的表达及其与肿瘤血管形成的关系

目的探讨碱性纤维母细胞生长因子(bFGF)和抑癌基因p53在星形细胞瘤中的表达及其与肿瘤血管形成的关系。方法应用原位杂交和免疫组织化学方法,检测60例星形细胞瘤石蜡包埋标本的bFGF和p53的表达。结果bFGF和p53mRNA阳性颗粒可见于血管内皮细胞(VEC)和肿瘤细胞,两者在VEC中的表达呈正相关关系,r=0.82,P<0.01,高级别星形细胞瘤表达bFGF和p53的强度高于低级别者,其差异具有显著性,P<0.01;bFGF在血管内皮细胞中的表达强度随血管密度增加而增加;bFGF和P53蛋白在血管EC中的表达与其相应的基因在同一位置的表达无相关性。结论bFGF具有促血管发生作用,此作用可能受p53抑癌基因调控;bFGF和p53均参与星形细胞瘤的恶性变过程。     

Microtubule-associated protein-2 immunoreactivity: a useful tool in the differential diagnosis of low-grade neuroepithelial tumors

Complex and variable morphological phenotypes pose a major challenge to the histopathological classification of neuroepithelial tumors. This applies in particular for low-grade gliomas and glio-neuronal tumors. Recently, we and others have identified microtubule-associated protein-2 (MAP2) as an immunohistochemical marker expressed in the majority of glial tumors. Characteristic cell morphologies can be recognized by MAP2 immunoreactivity in different glioma entities, i.e., process sparse oligodendroglial versus densely ramified astrocytic elements. Here, we describe MAP2-immunoreactivity patterns in a large series of various neuroepithelial tumors and related neoplasms (n=960). Immunohistochemical analysis led to the following conclusions: (1) specific pattern of MAP2-positive tumor cells can be identified in 95% of glial neoplasms; (2) ependymal tumors do not express MAP2 in their rosette-forming cell component; (3) tumors of the pineal gland as well as malignant embryonic tumors are also characterized by abundant MAP2 immunoreactivity; (4) virtually no MAP2 expression can be observed in the neoplastic glial component of glio-neuronal tumors, i.e. gangliogliomas; (5) malignant glial tumor variants (WHO grade III or IV) exhibit different and less specific MAP2 staining patterns compared to their benign counterparts (WHO grade I or II); (6) with the exception of melanomas and small cell lung cancers, MAP2 expression is very rare in metastatic and non-neuroepithelial tumors; (7) glial MAP2 expression was not detected in 56 non-neoplastic lesions. These data point towards MAP2 as valuable diagnostic tool for pattern recognition and differential diagnosis of low-grade neuroepithelial tumors.     

Operated low grade astrocytomas: a long term PET study on the effect of radiotherapy

The role of postoperative radiotherapy in patients with low grade gliomas is not established yet. PET with 11C methionine (MET) and 18F fluorodeoxyglucose (FDG) was used to perform cross sectional comparisons as well as within patient follow up studies in 30 operated patients with fibrillary astrocytoma WHO II. Uptake of tracer by tumour was quantified by radioactivity concentration ratios in tumour over contralateral brain (T/C). Comparing patients who did (n=13) or did not (n=17) receive external radiotherapy subsequent to first tumour resection, no differences in MET and FDG T/C between both groups were found during a postoperative period of 94 months (when recurrence and malignant progression of low grade astrocytomas are expected). Malignant progression occurred at a similar rate in both patient groups at a mean (SD) postoperative interval of 46 (26) months. Irrespective of whether radiotherapy was applied or not, malignant tumour recurrences showed higher T/C values (MET: 1.70 (0.64), FDG: 0.98 (0.23)) than recurrences without signs of malignancy (MET: 1.21 (0.21), FDG: 0.82 (0.08)) (Mann-Whitney: MET p=0.086, FDG p=0.035). The data show a relative lack of radiotherapy administered immediately after first tumour resection. In the course of disease, patients with tumours undergoing malignant progression may be identified with PET tracer methods.     

Apoptosis in glial tumors as determined by in situ nonradioactive labeling of DNA breaks

Tumor growth depends on cell division and cell death. To investigate the role of apoptosis in tumor cell death, we examined 83 cases of glial tumors using in situ nonradioactive tailing of DNA breaks. In addition, since p53 protein may participate in the regulation of apoptosis in glioblastoma, we compared the apoptosis ratio (AR) with the labeling index (LI) of p53 protein immunopositivity. The AR in glial tumor parenchyma ranged from 0 to 1.4%: mean AR ± standard deviation was 0.4 ± 0.4% (range, 0–1.4) for glioblastoma, 0.3 ± 0.3% (range, 0.01– 0.83) for anaplastic astrocytoma, 0.1 ± 0.1% (range, 0– 0.41) for low-grade astrocytoma, 0.006 ± 0.008% (range, 0–0.02) for pilocytic astrocytoma, 0.2 ± 0.2% (range, 0– 0.62) for oligodendroglioma and 0.003 ± 0.004% (range, 0–0.01) for ependymoma. ARs were significantly higher in higher-grade astrocytic tumors than in lower-grade tumors (Mann-Whitney U test: P = 0.0003), although wide variability in each group resulted in overlapping between the groups. p53 protein immunopositivity (more than 25% of nuclei) was found in 15 of 32 glioblastoma cases, while in the remaining 17 none or only a low percentage (up to 6%) of the nuclei were positive. In p53 protein-positive cases mean AR (0.51 ± 0.47%) was not significantly higher than that in p53 protein-negative cases (0.22 ± 0.23%; P = 0.1681). Received: 17 February 1995 / Revised: 12 June 1995 / Accepted: 30 August 1995