Oligodendroglial Component Research Articles

Sequencing IDH1/2 glioma mutation hotspots in gliomas and malignant peripheral nerve sheath tumors

Sequencing IDH1/2 glioma mutation hotspots in gliomas and malignant peripheral nerve sheath tumors

Primary glioblastoma with oligodendroglial differentiation has better clinical outcome but no difference in common biological markers compared with other types of glioblastoma

Glioblastoma multiforme with an oligodendroglial component (GBMO) has been recognized in the World Health Organization classification-however, the diagnostic criteria, molecular biology, and clinical outcome of primary GBMO remain unclear. Our aim was to investigate whether primary GBMO is a distinct clinicopathological subgroup of GBM and to determine the relative frequency of prognostic markers such as loss of heterozygosity (LOH) on 1p and/or 19q, O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation, and isocitrate dehydrogenase 1 (IDH1) mutation. We examined 288 cases of primary GBM and assessed the molecular markers in 57 GBMO and 50 cases of other primary GBM, correlating the data with clinical parameters and outcome. GBMO comprised 21.5% of our GBM specimens and showed significantly longer survival compared with our other GBM (12 mo vs 5.8 mo, P = .006); there was also a strong correlation with younger age at diagnosis (56.4 y vs 60.6 y, P = .005). Singular LOH of 19q (P = .04) conferred a 1.9-fold increased hazard of shorter survival. There was no difference in the frequencies of 1p or 19q deletion, MGMT promoter methylation, or IDH1 mutation (P = .8, P = 1.0, P = 1.0, respectively). Primary GBMO is a subgroup of GBM associated with longer survival and a younger age group but shows no difference in the frequency of LOH of 1p/19q, MGMT, and IDH1 mutation compared with other primary GBM.

Correlation between Cerebral Blood Volume Measurements by Perfusion-Weighted Magnetic Resonance Imaging and Two-Year Progression-Free Survival in Gliomas

Our goal was to determine whether relative cerebral blood volume (rCBV) can serve as an adjunct to histopathologic grading in the assessment of gliomas, with the hypothesis that rCBV can predict two-year survival. We evaluated 29 newly diagnosed gliomas (13 WHO grade II, seven grade III, nine grade IV; 17 astrocytomas, 12 oligodendroglial tumors). Dynamic susceptibility-weighted contrast-enhanced perfusion MR images and CBV maps were obtained. rCBVmax measurements (maximum tumor CBV/contralateral normal tissue CBV) and progression-free survival (PFS) were recorded. Receiver operating characteristic curves and Kaplan-Meier survival curves were calculated for rCBVmax and histologic grade. rCBVmax measurements differed between gliomas without (2.38 +/- 1.22) and with progression (5.57 +/- 2.84) over two years. The optimal rCBVmax cut-off value to predict progression was 2.95. rCBVmax < 2.95 was a significant predictor of two-year PFS, almost as accurate as WHO grade II. In the pure astrocytoma subgroup, the optimal rCBVmax cut-off value to predict progression was 2.85. In this group rCBVmax < 2.85 was a significant predictor of two-year PFS, an even better predictor of two-year PFS than WHO grade II. rCBVmax can be used to predict two-year PFS in patients with gliomas, independent of pathologic findings, especially in tumors without oligodendroglial components.

Multiple Microsurgical Resections for Repeated Recurrence of Glioblastoma Multiforme

There has been little evidence so far supporting further surgical intervention in case of repeated recurrence of glioblastoma multiforme (GBM). Thus, the efficacy and utility of repeated resection remains unclear but worthy of consideration. The aim of this study was to review the efficacy of multiple repeated resections in patients with recurrent GBM. Forty-two patients underwent repeated surgical resections for recurrent GBM. All patients who underwent >2 surgical interventions were clustered in group A. Group B were patients treated nonsurgically after resection of the first recurrence. Patients' treatment history, including surgical interventions, radiotherapy, chemotherapy regimens, postoperative complications, Karnofsky Performance Score, and survival rate were reviewed. Group A consisted of 10 patients (median age, 60.5 y) and group B of 32 patients (median age, 56.5 y). Histopathologic findings revealed typical GBM in 8 patients of group A and in 23 patients of group B. An oligodendroglial component was detected in 2 patients of group A and in 7 patients of group B. The median Karnofsky Performance Score after the first surgery for tumor recurrence was 80 in both groups (P=0.084). The median overall survival time was 26 months in patients of group A and 16 months in patients of group B (P=0.052). The 2-year survival rate of group A was 58.3% and significantly higher than in group B (29.0%; P=0.036). The 3-year survival rate of group A was 31.1% and 12.4% of group B (P=0.038). Microsurgical resection of repeatedly recurring GBM is likely to prolong survival. Repeated surgical resection may be considered as an effective treatment option in addition to radiochemotherapy in repeated GBM recurrence.

Immunohistochemical actinin-4 expression in infiltrating gliomas: association with WHO grade and differentiation

Actinin-4 is an isoform of nonmuscular α-actinin and actin-bundling protein that plays an important role in cancer invasion and metastasis by enhancing cellular motility. Recent studies have revealed an association between several clinicopathological profiles and actinin-4 overexpression in human cancers. In this study, we investigated the immunohistochemical actinin-4 expression in 39 infiltrating gliomas. The specimens included three diffuse astrocytomas, three oligodendrogliomas, one oligoastrocytoma, two anaplastic astrocytomas, four anaplastic oligodendrogliomas, three anaplastic oligoastrocytomas, 17 glioblastomas, four gliosarcomas, and two glioblastomas with oligodendroglial component. All seven World Health Organization (WHO) grade II tumors were negative for actinin-4, whereas 20 of 22 tumors with strong actinin-4 expression were WHO grade IV. Actinin-4 expression was significantly associated with histological grade (P<0.0001) and proliferative activity measured by Ki-67 staining (P=0.0045). Notably, actinin-4 expression was more pronounced in high-grade astrocytic tumors than oligodendroglial tumors (P<0.0001). Additionally, pseudopalisading cells in glioblastoma exhibited stronger actinin-4 expression than the rest, likely reflecting enhanced cellular motility in pseudopalisades. This study is the first to demonstrate significant correlation between actinin-4 expression and tumor grade using clinical glioma samples. Although diagnostic utility of this marker awaits future exploration, actinin-4 may help distinguish between astrocytic and oligodendroglial lines of differentiation.

Diagnostic implications of IDH1-R132H and OLIG2 expression patterns in rare and challenging glioblastoma variants

Recent work has demonstrated that nearly all diffuse gliomas display nuclear immunoreactivity for the bHLH transcription factor OLIG2, and the R132H mutant isocitrate dehydrogenase 1 (IDH1) protein is expressed in the majority of diffuse gliomas other than primary glioblastoma. However, these antibodies have not been widely applied to rarer glioblastoma variants, which can be diagnostically challenging when the astrocytic features are subtle. We therefore surveyed the expression patterns of OLIG2 and IDH1 in 167 non-conventional glioblastomas, including 45 small cell glioblastomas, 45 gliosarcomas, 34 glioblastomas with primitive neuroectodermal tumor-like foci (PNET-like foci), 23 with an oligodendroglial component, 11 granular cell glioblastomas, and 9 giant cell glioblastomas. OLIG2 was strongly expressed in all glioblastomas with oligodendroglial component, 98% of small cell glioblastomas, and all granular cell glioblastomas, the latter being particularly helpful in ruling out macrophage-rich lesions. In 74% of glioblastomas with PNET-like foci, OLIG2 expression was retained in the PNET-like foci, providing a useful distinction from central nervous system PNETs. The glial component of gliosarcomas was OLIG2 positive in 93% of cases, but only 14% retained focal expression in the sarcomatous component; as such this marker would not reliably distinguish these from pure sarcoma in most cases. OLIG2 was expressed in 67% of giant cell glioblastomas. IDH1 was expressed in 55% of glioblastomas with oligodendroglial component, 15% of glioblastomas with PNET-like foci, 7% of gliosarcomas, and none of the small cell, granular cell, or giant cell glioblastomas. This provides further support for the notion that most glioblastomas with oligodendroglial component are secondary, while small cell glioblastomas, granular cell glioblastomas, and giant cell glioblastomas are primary variants. Therefore, in one of the most challenging differential diagnoses, IDH1 positivity could provide strong support for glioblastoma with oligodendroglial component, while essentially excluding small cell glioblastoma.

Glioblastomas with oligodendroglial component have the same clinical phenotype as classical glioblastomas

Introduction. Glioblastomas are the commonest primary brain tumour and are considered one of the most heterogeneous tumour types. The introduction of a glioblastoma with oligodendroglial component (GBM + O) in the latest WHO Classification of Tumours of the Central Nervous System 1 was to help with this. There has been conflicting evidence as to whether this tumour conferred a better prognosis than classical glioblastoma (GBM). The aim of this study was to study the clinical phenotype of these GBM + O tumours and compare it to the classical GBM. Materials and methods. All patients with histological evidence of a glioblastoma between 1st January 2007 and 31st January 2011 were identified from the Neuropathology Database. Clinical and radiological details were obtained for all patients. The overall survival of patients who were treated with chemoradiotherapy was obtained and the GBM + O cohort compared to the classical GBM cohort. Results. Three hundred and ninety-six patients with newly diagnosed glioblastomas were identified: 294 (74.2%) had classical GBM and 102 (25.6%) had GBM + O. The two cohorts presented at a similar age (61.1 years GBM + O vs. 63.2 years GBM; P = 0.09) and were matched for sex and side of the tumour. GBM + O were more likely to be located in the frontal lobes (38.2% for GBM + O vs. 27.2% for GBM: P = 0.04). In the group that was treated with chemoradiotherapy the overall survival was similar (median survival GBM + O 361 days vs. 379 days GBM; Log Rank 0.61, P = 0.43). Conclusion. The presence of an oligodendroglial component does not confer any improvement in survival and has a similar clinical phenotype to classical GBMs.

Glioblastoma with oligodendroglial component represents a subgroup of glioblastoma with high prevalence of IDH1 mutation and association with younger age

Glioblastoma with an oligodendroglial component (GBMO) is recognized as a subgroup of glioblastoma (GBM); however, the molecular and clinicopathological characteristics of GBMO are obscure. We evaluated the methylation status of MGMT, IDH1/2 mutation, deletions of 1p and 19q and expression of IDH1, p53, p16, CD151, and galectin3 proteins in 42 GBMOs (32 primary and 10 secondary tumors). Our aims were to correlate our molecular findings with clinicopathologic features, and to compare molecular-to-clinical correlations in the 42 GBMOs with the corresponding correlations in 45 GBMs. GBMO was subdivided into two subgroups according to the predominant cell component comprising >50 % of tumors: the astrocytic predominant type (GBMO-A) and oligodendroglioma predominant type (GBMO-O). Methylation of MGMT, IDH1/2 mutation, and co-deletion of 1p and 19q were found in 31.0, 26.2, and 17.9 % of patients with GBMO, respectively. Clinicopathological and molecular characteristics did not differ significantly between GBMO-A and GBMO-O. However, patients with GBMO-O experienced better outcomes than patients with GBMO-A (p = 0.007). On multivariate analysis the predominant cell type was an independent prognostic factor in overall survival [hazard ratio 4.2 (95 % confidence interval 1.4-12.8), p = 0.011]. When compared to patients with classic GBM, those with GBMO were younger (49.21 vs. 57.47, p = 0.003) and more frequently had tumors with IDH1 mutation (23.8 vs. 4.4 %, p = 0.009). Survival was similar in patients with GBMO and with classic GBM. Based on these results, GBMO may represent a subgroup of GBM that is associated with IDH1 mutation and younger age, although similar to classic GBM in prognosis.

Association of loss of heterozygosity with shorter survival in primary glioblastoma patients

Loss of heterozygosity (LOH) co-deletion 1p/19q, MGMT promoter methylation and/or IDH1 mutation generally signify a better prognosis for patients with glioma. However, the influence of 1p/19q co-deletion and the LOH on other chromosomes in primary glioblastoma on survival is still debatable. The aim of our study was to identify LOH on chromosomes 1p, 19q, 9p, 10q, 13q, and 17p, and evaluate their impact either alone or 1p/19q co-deletion or by groups of LOH on the overall survival of 42 primary glioblastoma patients without an oligodendroglial component. These patients were additionally molecularly characterized for EGFR amplification, IDH1 mutations and TP53 mutations. We assessed their influence on the overall survival of glioblastoma patients. LOH in at least one of the loci on all examined chromosomes was detected in 65% of cases and was significantly associated with shorter overall survival (hazard ratio 3.07; 95% CI: 1.29-7.31, p = 0.006). 1p/19q co-deletion was infrequent (7.14%) and had no impact on overall survival. Our results indicate that in primary glioblastoma a specific LOH group analysis may be important for the prognosis. LOH 1p/19q co-deletion is rare in glioblastoma without an oligodendroglial component and has no impact on patient survival.

Promoter Hypermethylation of theEMP3Gene in a Series of 229 Human Gliomas

The epithelial membrane protein 3 (EMP3) is a candidate tumor suppressor gene in the critical region 19q13.3 for several solid tumors, including tumors of the nervous systems. The aim of this study was to investigate the EMP3 promoter hypermethylation status in a series of 229 astrocytic and oligodendroglial tumors and in 16 GBM cell lines. The analysis was performed by methylation-specific PCR and capillary electrophoresis. Furthermore, the EMP3 expression at protein level was evaluated by immunohistochemistry and Western blotting analysis. Associations of EMP3 hypermethylation with total 1p/19q codeletion, MGMT promoter hypermethylation, IDH1/IDH2 and TP53 mutations, and EGFR amplification were studied, as well as its prognostic significance. The EMP3 promoter hypermethylation has been found in 39.5% of gliomas. It prevailed in low-grade tumors, especially in gliomas with an oligodendroglial component, and in sGBMs upon pGBMs. In oligodendroglial tumors, it was strongly associated with both IDH1/IDH2 mutations and total 1p/19q codeletion and inversely with EGFR gene amplification. No association was found with MGMT hypermethylation and TP53 mutations. In the whole series, the EMP3 hypermethylation status correlated with 19q13.3 loss and lack of EMP3 expression at protein level. A favorable prognostic significance on overall survival of the EMP3 promoter hypermethylation was found in patients with oligodendroglial tumors.

Combined temozolomide and radiation as an initial treatment for anaplastic glioma

Combined temozolomide (TMZ) and radiation therapy (RT) is often used as initial treatment for anaplastic glioma. However, there is no prospective randomized data available that proves the efficacy of the combination for anaplastic glioma. In this retrospective study we aimed to compare the outcome of patients who had combined TMZ and RT with those who had RT alone for the initial treatment of anaplastic glioma in our centers. Patients with anaplastic astrocytoma or oligoastrocytoma treated at our centers between 2000 and 2010 were reviewed. Only patients who received initial RT or concurrent TMZ and RT (TMZ-RT) were included. Of 62 patients, 55 were less than 66-years old; 36 (58.1%) had a tumor resection and 26 had a biopsy only. An oligodendroglial component in their tumor histology was present in 21 patients (33.9%). At a median follow up of 20.7 months for all patients, median progression-free survival was similar for the two treatment groups (RT alone: 16.7 months (95% CI 9.4, 34.8 months) versus TMZ-RT: 14.8 months (95% CI 8.6, 28.6 months, P = NS). Median overall survival was 27.4 months (95% CI 10.6, not estimable [NE] months) for patients who had RT alone and 34.1 months (95% CI 19.8, 42.1 months) for those who had TMZ-RT. No significant benefit of combined TMZ with RT compared to RT alone was observed as the initial treatment of anaplastic glioma. Prospective randomized trials are needed to evaluate the optimal treatment for this disease.

Prediction of oligodendroglial histology and LOH 1p/19q using dynamic [18F]FET-PET imaging in intracranial WHO grade II and III gliomas

Oligodendroglial components (OC) and loss of heterozygosity on chromosomes 1p and 19q (LOH 1p/19q) are associated with better outcome in patients with glioma. We aimed to assess the fitness of [(18)F]fluoroethyltyrosine positron-emission-tomography (FET-PET) for noninvasively identifying these important prognostic/predictive factors. One hundred forty-four patients with MRI-suspected WHO grade II and III glioma underwent FET-PET scans prior to histological diagnosis. FET-PET analyses included maximal tumoral uptake (SUV(max)/BG), biological tumor volume (BTV), mean tumoral uptake (SUV(mean)/BG), total tumoral uptake (SUV(total)/BG), and kinetic analysis. Suspicion of OC was based on static and dynamic FET-uptake parameters. PET results were correlated with histology and 1p/19q status. OC tumors exhibited significantly higher uptake values, compared with astrocytomas (AC) (SUV(max)/BG 3.1 vs 2.3, BTV 15.5 mL vs 7.2 mL, SUV(total)/BG 38.5 vs 17.4, P < .01 each; SUV(mean)/BG 2.2 vs 2.1, P < .05). These differences were more pronounced in WHO grade II gliomas. Comparable results were found with respect to 1p/19q status. Kinetic analysis misclassified 18 of 34 low-grade OC tumors as high-grade glioma but misclassified only 5 of 45 of the low-grade ACs. FET-based suspicion of OC resulted in concordance rates of both 76% for the prediction of OC and LOH 1p/19q. FET-uptake was significantly higher in gliomas with OC, compared with AC, and likewise in 1p/19q codeleted, compared with noncodeleted tumors. However, FET-PET analysis did not reliably predict the presence of OC/LOH 1p/19q in the individual patient, mostly because of an overlap in PET characteristics of OC tumors and high-grade AC. Histological examination is still required for an accurate diagnosis.

Référentiel gliomes diffus de l’adulte de grade OMS II, III et IV : anatomie pathologique et biologie

Pathological diagnosis plays a major role in the therapeutic management of adult diffuse gliomas. It is based on the histopathological analysis of a representative specimen. Therefore pathologists might be aware of the neuroradiological features of the lesions. Pathologists play a major role in the management of biological resources. Pathologists should classify adult gliomas according to WHO 2007 classification (histological subtype and grade). In addition, in order to provide the histomolecular classification of adult gliomas, search for molecular markers of diagnostic, prognostic or predictive of therapeutic responses must be performed by appropriate and validated immunohistochemical and molecular techniques. In all diffuse gliomas, whatever their grade, search for IDH1 R132H and P53 expression is required. Search for IDH1 minor mutations and IDH2 mutations is required in grade II and III IDH1 R132H negative gliomas whereas 1p19q codeletion should be searched for in grade II and III gliomas with an oligodendroglial component. Search for EGFR amplification and MGMT promoter methylation is recommended. It is strongly recommended to fill the standardized form for pathology and molecular features (validated by the French Society of Neuropathology) in all adult diffuse gliomas.

Glutamate is associated with a higher risk of seizures in patients with gliomas

To investigate the relationship of glutamate and glutamate transporter expression in human gliomas and surrounding peritumoral brain to the presence of tumor-associated seizures (TAS). We studied a retrospective (group 1: 190 patients) and then a prospective (group 2: 98 patients) cohort of patients who underwent a craniotomy for a supratentorial glioma. Tumor and peritumor tissue specimens were assayed for glutamate concentration and expression of glial glutamate transporters. Differences between the seizure (TAS) and seizure-free (non-TAS) groups were compared. A total of 42% of patients had TAS, with 95% of seizures first occurring preoperatively. Clinical factors independently associated with risk of TAS were younger age, temporal lobe location, and tumors with oligodendroglial components. Molecular features in tumor specimens associated with TAS were higher glutamate concentrations, reduced EAAT2 expression, and increased system X(c)(-) expression. In group 2, these results were also replicated in the peritumor tissue. Logistic regression analysis identified raised glutamate concentrations in tumor and peritumor tissue, increased expression of peritumor system X(c)(-), younger age, temporal lobe location, and tumors with oligodendroglial components as independently predictive of preoperative seizures. Relative increased glutamate concentration in gliomas, and altered glutamate transporter expression, are associated with the presence of TAS and may play a mechanistic role in their pathogenesis.

Prognostic Implication of Histological Oligodendroglial Tumor Component: Clinicopathological Analysis of 111 Cases of Malignant Gliomas

The favorable prognosis of high-grade oligodendroglial tumor such as glioblastoma (GBM) with oligodendroglioma component (GBMO) has been suggested; however, the studies which examine the prognostic significance of oligodendroglial tumor were limited. In this study, we performed a histopathology-based reevaluation of 111 cases of high grade gliomas according to the latest World Health Organization (WHO), and compared the clinical outcomes between oligodendroglial tumors and pure astrocytic tumors. The survival analysis revealed that the patients with high grade oligodendroglial tumor including GBMO significantly indicated better prognosis compared to the patients with high grade pure astrocytic tumors (GBM and AA, anaplastic astrocytoma) as expected, and the obtained survival curves were almost identical to those from the patients with conventional Grade III or Grade IV tumors, respectively. Moreover, if the cases of oligodendroglial tumor were histopathologically excluded, the patients with AA exhibited extremely poor prognosis which was similar to that of GBM, suggesting that the histological identification of oligodendroglial tumor component, even partially, prescribe the prognosis of high grade glioma patients. This is the prominent report of retrospective clinicopathological analysis for high-grade gliomas throughout Grade III and IV, especially referring to the prognostic value of histological oligodendroglial tumor component; in addition, our results might offer an alternative aspect for the grading of high-grade astrocytic/oligodendroglial tumors.

Clonal Analysis in Recurrent Astrocytic, Oligoastrocytic and Oligodendroglial Tumors Implicates IDH1- Mutation as Common Tumor Initiating Event

BackgroundTo investigate the dynamics of inter- and intratumoral molecular alterations during tumor progression in recurrent gliomas.Methodology/Principal FindingsTo address intertumoral heterogeneity we investigated non- microdissected tumor tissue of 106 gliomas representing 51 recurrent tumors. To address intratumoral heterogeneity a set of 16 gliomas representing 7 tumor pairs with at least one recurrence, and 4 single mixed gliomas were investigated by microdissection of distinct oligodendroglial and astrocytic tumor components. All tumors and tumor components were analyzed for allelic loss of 1p/19q (LOH 1p/19q), for TP53- mutations and for R132 mutations in the IDH1 gene. The investigation of non- microdissected tumor tissue revealed clonality in 75% (38/51). Aberrant molecular alterations upon recurrence were detected in 25% (13/51). 64% (9/14) of these were novel and associated with tumor progression. Loss of previously detected alterations was observed in 36% (5/14). One tumor pair (1/14; 7%) was significant for both. Intratumoral clonality was detected in 57% (4/7) of the microdissected tumor pairs and in 75% (3/4) of single microdissected tumors. 43% (3/7) of tumor pairs and one single tumor (25%) revealed intratumoral heterogeneity. While intratumoral heterogeneity affected both the TP53- mutational status and the LOH1p/19q status, all tumors with intratumoral heterogeneity shared the R132 IDH1- mutation as a common feature in both their microdissected components.Conclusions/SignificanceThe majority of recurrent gliomas are of monoclonal origin. However, the detection of divertive tumor cell clones in morphological distinct tumor components sharing IDH1- mutations as early event may provide insight into the tumorigenesis of true mixed gliomas.

Recurrent scalp metastasis from glioblastoma following resection

A 62-year-old right-handed male presented with several onths of mild headaches, word-finding difficulties, and 25 pound eight loss. MRI showed an irregularly enhancing intra-axial ass lesion in the left frontal lobe extending to the ependymal urface and measuring approximately 6 cm in maximum diamter. Left frontal craniotomy for subtotal resection of the mass as performed. Pathologic assessment revealed a WHO Grade IV lioblastoma with oligodendroglial component, MGMT promoter ethylated, EGFR amplified, and 1p deleted/19q intact (Fig. 1). he patient subsequently received 60 Gy of radiation therapy and emozolomide (75 mg/m2 21/28 days). Ten months after the subtoal resection of the intracranial mass, follow-up MRI revealed n avidly enhancing, infiltrative nodular lesion with restricted

Abstract 3135: Epigenetic regulation of miR-1275 through histone H3 lysine 27 trimethylation during human glioma stem-like cell differentiation

Abstract Functional and morphological heterogeneity characterizes aggressive glioblastoma and contributes to invasion, metastasis and drug resistance. The molecular mechanisms underlying this heterogeneity are poorly understood. Recent studies have revealed that tumors contain a minor population of tumor-initiating cells, called cancer stem cells (CSCs). The CSCs are considered able to aberrantly differentiate into diverse cell types. Such stem-like cancer cells have been well characterized in glioblastoma multiforme, and are referred to as glioma stem-like cells (GSCs). Using GSCs as a model, we investigated the roles of micro-RNA (miR) in GSCs differentiation. miR-microarray showed that 19 and 48 miRs were commonly upregulated and downregulated in two GSC lines during the differentiation, respectively. Among those miRs, quantitative-PCR analysis showed that miR-1275 was consistently downregulated during the GSC differentiation, while the expression of its target, oligodendrocyte specific protein (OSP/CLDN11), a marker of oligodendrocyte, was upregulated. Compellingly, inhibition of miR-1275 using specific antisense oligonucleotide increased the expression of OSP in GSC. Epigenetic analysis revealed that level of histone H3 lysine 27 trimethylation(H3K27me3) was enriched in the promoter of pri-miR-1275 during the GSC differentiation. Treatment of 3-Dezaneplanocin-A, an inhibitor of H3K27me3, impaired the GSC differentiation in parallel with sustained miR-1275 expression. In general, astrocytic component is the most prevalent in glioblastomas, while a subset of cases also contain an oligodendroglial component in the tumors. Our results illuminated the epigenetic regulatory pathways of miR-1275 closely associated with oligodendroglial differentiation, which may contribute to the tissue heterogeneity formation of glioblastomas. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3135. doi:1538-7445.AM2012-3135

Glioblastoma with oligodendroglial components: glioblastoma or anaplastic oligodendroglial tumors

There have been some recent reports about glioblastoma with oligodendroglial (OG) components and malignant glioma with primitive neuroectodermal tumor (PNET)-like components. We investigated whether the presence and extent of OG components and PNET-like components influenced the prognosis in patients with glioblastoma. Eighty-six patients with glioblastoma were divided into an OG group (28 %), which revealed areas with a honeycomb appearance, and a non-OG group (72 %) without a honeycomb appearance. Patients with glioblastoma were also divided into a PNET group (27 %), which revealed areas with PNET-like features defined as neoplastic cells with high N/C ratios and hyperchromatic oval-carrot-shaped nuclei, and lacked the typical honeycomb appearance, and a non-PNET group (73 %) without PNET features. There were no significant differences in overall survival among the OG, the non-OG, the PNET, and the non-PNET groups. Two patients who survived longer than 36 months had both OG and PNET components with 1p or 19q loss of heterozygosity. Perinuclear halo, which is a characteristic feature of oligodendrogliomas, is an artifact of tissue fixation. Therefore, we should not readily use the term glioblastoma with OG components. PNET-like components, which are considered rare in malignant gliomas, may be frequently identified in glioblastomas.

Glioblastoma with an oligodendroglioma component: distinct clinical behavior, genetic alterations, and outcome

Glioblastomas (GBMs) containing foci that resemble oligodendroglioma are defined as GBM with oligodendroglioma component (GBMO). However, whether GBMO is a distinct clinicopathological variant of GBM or merely represents a divergent pattern of differentiation remains controversial. We investigated 219 consecutive primary GBMs, of which 40 (18.3%) were confirmed as GBMOs. The clinical features and genetic profiles of the GBMOs were analyzed and compared with the conventional GBMs. The GBMO group showed more frequent tumor-related seizures (P= .027), higher frequency of IDH1 mutation (31% vs. <5%, P= .015), lower MGMT expression (P= .016), and longer survival (19.0 vs. 13.2 months; P= .022). In multivariate Cox regression analyses, presence of an oligodendroglioma component was predictive of longer survival (P= .001), but the extent of the oligodendroglial component appeared not to be linked to prognosis (P= .664). The codeletions of 1p/19q, somewhat surprisingly, were infrequent (<5%) in both GBMO and conventional GBM. In addition, the response to aggressive therapy differed: the GBMO group had no survival advantage associated with aggressive treatment protocols, whereas a clear treatment effect was observed in the conventional GBM group. Collectively, the clinical behavior and genetic alterations of GBMO thus differs from those of conventional GBM. Presence of an oligodendroglial component may therefore be a useful classification and stratification variable in therapeutic trials of GBMs.