Deletion mapping of chromosome 19 in human gliomas

There is evidence that a putative glioma tumor suppressor locus resides on the long arm of chromosome 19. We present data on 161 gliomas from IS6 patients, which were studied by microsatellite analysis for loss of heterozygosity (LOH) on chromosome 19. Eight loci on the long arm and 2 loci on the short arm of chromosome IV were examined. LOH on I9qwas observed in 3/19 astrocytomas (WHO grade II), 12/27 anaplastic astrocytomas (WHO grade III), 16/76 cases of glioblastoma multiforme WHO (grade IV), 4/9 oligodendrogliomas (WHO grade II), 3/5 anaplastic oligodendrogliomas (WHO grade III), 5/9 mixed oligo-astrocytomas (WHO grade II) and 8/10 anaplastic oligo-astrocytomas (WHO grade III). While 31 of the tumors with LOH on chromosomal arm I9q exhibited allelic loss at every informative locus, 20 tumors showed terminal or interstitial deletions. In contrast to astrocytomas and glioblastomas, tumors with an oligodendroglial component had predominantly lost the entire long arm of chromosome 19. The common region of overlap in gliomas was located on 19q 13.2-q 13.4 between the markers D 19S 178 and D 19S 180. Our data confirm the involvement of a putative tumor suppressor gene on chromosomal arm 19q in gliomas and assign this gene to 19q 13.2-q 13.4.     

Prognostic variables in oligodendroglial tumors: a single-institution study of 95 cases

We analyzed the relationships among clinical variables, histology, 1p/19q status, and outcome in 95 patients with oligodendroglial tumors. The study enrolled adult patients who underwent first-time surgery for a supratentorial oligodendroglial tumor at Oslo University Hospital, Rikshospitalet. Tumors were: 27 oligodendrogliomas, WHO grade II; 32 oligoastrocytomas, WHO grade II; 16 anaplastic oligodendrogliomas, WHO grade III; 14 anaplastic oligoastrocytomas, WHO grade III; and 6 glioblastomas with a major oligodendroglial component, WHO grade IV. The clinical files were reviewed. Three neuropathologists evaluated the histological slides independently. Loss-of-heterozygosity analysis for 1p and 19q was performed by PCR. Favorable prognostic factors from univariate analyses included seizures as presenting symptom, female sex, location in the frontal lobe, low WHO grade, classic histology, absence of gemistocytic cells, and combined 1p/19q loss. Solitary 19q loss was a negative prognostic marker. 1p/19q status was of prognostic significance in both tumors with classic and nonclassic oligodendroglial histology. In the multivariate analysis, WHO grade II (P< .001), frontal tumor location (P= .002), and combined 1p/19q loss (P< .001) remained favorable prognostic variables. Our results suggest that tumor location, WHO grade, and 1p/19q status are important independent variables associated with survival in oligodendroglial tumors. The study suggests that solitary 19q loss is a negative prognostic variable and that 1p/19q loss is associated with prolonged survival also in oligodendroglial tumors without classic histology.     

Molecular analysis of chromosomh 1 abnormalities in human gliomas reveals frequent loss of 1p in oligodendroglial tumors

Alterations of the short arm of chromosome I are recurrently found in cytogenetic analysis of malignant gliomas, and deletions of Ip36-p32 region characterize at least the higher-grade tumors, glioblsstoma multiforme. Molecular analysis of tumor-derived and normal genomic DNA from 57 cases of gliomas, using a panel of chromosome I-specific DNA probes showed LOH in 16 tumors. Allelic losses on I p were primarily restricted to glioblastoma multiforme (2/II) and to tumors with a major oligodendroglial component: grade II oligodendrogliomas (6/6), grade III anaplastic oligodendrogliomas (5/6) and grade II-III mixed oligo-astrocytomas (2/3). Losses for Iq markers were detected in only I tumor (glioblastoma multiforme). Our data suggest that anomalies of Ip primarily characterize oligodendrogliomas, whereas they are rare events in astrocytic tumors and indicate that a tumor-suppressor gene on I p36-p32 is involved in the development of brain tumors with oligodendroglial differentiation. © 1994 Wiley-Liss, Inc.     

Correlation of histology and molecular genetic analysis of 1p, 19q, 10q, TP53, EGFR, CDK4, and CDKN2A in 91 astrocytic and oligodendroglial tumors.

PURPOSE: The histological diagnosis of human gliomas is of great importance for estimating patient prognosis and guiding therapy but suffers from being subjective and, therefore, variable. We hypothesized that molecular genetic analysis could provide a more objective means to classify tumors and, thus, reduce diagnostic variability. EXPERIMENTAL DESIGN: We performed molecular genetic analysis on 91 nonselected gliomas for 1p, 19q, 10q, TP53, epidermal growth factor receptor, and cyclin-dependent kinase 4 abnormalities and compared with the consensus diagnoses established among four independent neuropathologists. RESULTS: There were six astrocytomas, seven anaplastic astrocytomas, 45 glioblastomas, 21 oligodendrogliomas, eight anaplastic oligodendrogliomas, three oligoastrocytomas, and one anaplastic oligoastrocytoma. Twenty-nine cases had either 1p or 19qloss of heterozygosity (LOH) while retaining both copies of 10q, of which 25 (86%) were histologically oligodendroglioma, anaplastic oligodendroglioma, oligoastrocytoma, or anaplastic oligoastrocytoma. As for the oligodendroglial tumors, unanimous agreement of the initial diagnoses was almost restricted to those cases with combined 1p/19qLOH, whereas all nine tumors without 1p loss initially received variable diagnoses. Interestingly, TP53 mutation was inversely related to 1pLOH in all gliomas (P = 0.0003) but not 19qLOH (P = 0.15). CONCLUSIONS: These data demonstrate that molecular genetic analysis of 1p/19q/10q/TP53 has significant diagnostic value, especially in detecting oligodendroglial tumors. In addition, 1pLOH and TP53 mutations in gliomas may be markers of oligodendroglial and astrocytic pathways, respectively, which may separate gliomas with the same histological diagnosis, especially oligodendroglial tumors and glioblastomas. Testing for those molecular genetic alterations would be essential to obtain more homogeneous sets of gliomas for the future clinical studies.     

Calcification on CT is a simple and valuable preoperative indicator of 1p/19q loss of heterozygosity in supratentorial brain tumors that are suspected grade II and III gliomas

Gliomas with 1p/19q loss of heterozygosity (LOH) are known to be associated with longer patient survival and higher sensitivity to treatment than tumors without 1p/19q LOH. This study was designed to clarify whether the preoperative finding of calcification on CT was correlated with 1p/19q LOH in patients with suspected WHO grade II and III gliomas. This study included 250 adult patients who underwent resection for primary supratentorial tumors at Tokyo Women’s Medical University Hospital. The tumors were suspected, based on MRI findings, to be WHO grade II or III gliomas. The presence of calcification on the patients’ CT images was qualitatively evaluated before treatment. After surgery, the resected tumors were examined to determine their 1p/19q status and mutations of IDH1 and p53. The presence of calcification was significantly correlated with 1p/19q LOH (P < 0.0001), with a positive predictive value of 91 %. The tumors of all the 78 patients with calcification were diagnosed as oligodendroglial tumors. Seventy of these patients showed classic oligodendroglial features, while 8 patients showed non-classic features. Calcification on CT is a simple and valuable preoperative indicator of 1p/19q LOH in supratentorial brain tumors that are suspected to be WHO grade II and III gliomas.     

Magnetic resonance perfusion-weighted imaging defines angiogenic subtypes of oligodendroglioma according to 1p19q and EGFR status

1p19q LOH has been shown to predict radio- and chemosensitivity and prolonged survival in oligodendrogliomas (OLs). We have recently shown that magnetic resonance perfusion-weighted imaging (MR-PWI) may be useful in predicting the histopathological grade or cytogenetic type of oligodendroglial neoplasms. MR-PWI allows noninvasive determination of relative tumor blood volume (rTBV), which may reflect the degree of neoplastic angiogenesis and metabolism. The present study was aimed to correlate rTBV to the angiogenic markers and EGFR expression in oligodendroglial tumors with 1p/19q LOH or 1p LOH (Group 1) and 1p19q intact alleles or 19q LOH (Group 2), respectively. In WHO grade II neoplasms, Group 1 showed significantly greater rTBV than Group 2 (P = 0.013). However, the differences between Group 1 and Group 2 were not significant in grade III tumors. Probe-based real-time RT-PCR analyses showed that 12% of Group 2 high-grade tumors with intact 1p19q exhibited dramatic EGFR overexpression (designated EGFR-high). Grade III neoplasms showed a significantly higher rTBV than grade II neoplasms. Group 1 tumors showed significantly higher rTBV than Group 2 tumors, independent of the EGFR-high subtype. Real-time RT-PCR analyses showed increased expression of VEGF, CD31 and CD105 in Group 1 tumors as compared to Group 2 tumors, excluding the EGFR-high subtype. Multivariable linear regression analysis showed a significant association of rTBV with 1p19q LOH, and expression of EGFR and VEGF. Therefore, the combined use of extensive molecular profiling and advanced MR imaging modalities may improve the accuracy of tumor grading, provide prognostic information, and has the potential to influence treatment decisions. Gurpreet S. Kapoor, Timothy A. Gocke and Sanjeev Chawla contributed equally to this study.     

Reclassification of oligoastrocytomas by loss of heterozygosity studies

Oligoastrocytomas (OAs) are WHO grade II or III tumors composed of a mixture of 2 neoplastic cell types morphologically resembling the cells in oligodendrogliomas and diffuse astrocytomas. Investigations on the genetic profile of OAs may yield important information for their classification and help for their clinical management. We have studied, in 94 OAs (46 WHO grade II and 48 WHO grade III), the patterns of loss of heterozygosity (LOH) of 4 genomic regions: 1p, 19q, 17p and 10q. Results were as follows: LOH 1p was present in 46% of the tumors; LOH 19q in 45%; LOH 17p in 22%; LOH 10q in 16%. LOH 1p and 19q were associated in 32%, other LOH associations were rare (<3%). Patients had a median follow-up of 30 months. Patients without LOH on 1p had shorter progression free survival than patients with LOH on 1p: 30 vs. 132 months, p < 0.0001. MRI indicated that tumors without LOH on 1p were often temporal (p < 0.02), and showed signal inhomogeneity on T1 and T2 images (p < 0.02) and contrast enhancement (p < 0.04). Thus, LOH on 1p identifies two subgroups of OAs. OAs without LOH on 1p behave like WHO grade II or III diffuse astrocytomas: they have shorter survival, MRI characteristics implying malignancy and genetic alterations associated with tumor progression. OAs with LOH on 1p, on the other hand, behave like WHO grade II or III oligodendrogliomas with 1p loss: they are associated with longer survival and do not have MRI or genetic alterations associated with malignancy. These findings suggest that the definition of OAs or mixed gliomas could be reshaped in agreement with the genetic information.     

胶质瘤染色体1p和19q杂合性缺失与O6-甲基鸟嘌呤DNA甲基转移酶p53和Ki-67蛋白表达的关系

目的 探讨胶质瘤染色体1p和19q杂合性缺失(LOH)与O6-甲基鸟嘌呤DNA甲基转移酶(MGMT)、p53和Ki-67蛋白表达的关系.方法 采集146例胶质瘤(45例少突胶质细胞瘤、42例少突星形细胞瘤和59例星形细胞瘤)的肿瘤组织和血液标本,采用聚合酶链反应结合变性高效液相色谱技术检测染色体1p和19q LOH,免疫组化法检测肿瘤组织中MGMT、p53和Ki-67蛋白的表达,并进一步分析其与胶质瘤临床病理特征的关系.结果 少突胶质细胞肿瘤和星形细胞瘤中,1p LOH的发生率分别为59.8％和33.9％,差异有统计学意义(P=0.002);1p和19q LOH的发生率分别为42.5％和16.9％,差异有统计学意义(P=0.001).MGMT低表达和Ki-67高表达多发生于少突胶质细胞肿瘤中,发生率分别为65.5％和54.0％,而p53高表达多发生于星形细胞瘤和少突星形细胞瘤中,发生率为75.2％.在87例少突胶质细胞肿瘤中,1p LOH和MGMT蛋白低表达多发生于Ⅱ级少突胶质细胞肿瘤中,发生率分别为72.5％和87.5％,而p53和Ki-67蛋白高表达多发生于Ⅲ级少突胶质细胞肿瘤中,发生率分别为83.0％和76.6％.1p和19q LOH在非颞叶和颞叶肿瘤的发生率分别为55.6％和21.2％(P=0.002).1p LOH与19q LOH、MGMT蛋白表达与p53蛋白表达、MGMT蛋白表达与Ki-67蛋白表达、1p和19q LOH与p53蛋白表达、1p LOH与Ki-67蛋白表达均有关(均P＜0.05).结论 1p和19q LOH及MGMT、p53和Ki-67的蛋白表达与胶质瘤的临床病理学特征有关,检测其LOH状态和表达水平对胶质瘤的诊断和治疗具有指导作用.     

Loss of Heterozygosity for Loci on Chromosome Arms 1p and 10q in Oligodendroglial Tumors: Relationship to Outcome and Chemosensitivity

Oligodendroglial tumors frequently have deletions of chromosomal loci on 1p and 19q. Loss of heterozygosity (LOH) of chromosome 10 may be a negative prognostic factor. We reviewed 23 patients with oligodendroglial tumors, to evaluate the frequency of 1p and 10q LOH and correlate with clinical outcome. Three loci (D1S402, D1S1172, MCT118) on 1p and 2 loci (D10S520 and D10S521) on 10q were analyzed for LOH using PCR techniques. Sixteen oligodendrogliomas (6 low grade and 10 anaplastic) and 7 oligoastrocytomas (1 low grade and 6 anaplastic) were studied. Overall 14/22 (64%) showed 1p LOH and 7/23 (30%) showed 10q LOH. Of 7 patients with some response to chemotherapy, all showed 1p LOH and none had 10q LOH. Of 5 patients with stable or progressive disease, 1 had 1p LOH and 2 showed 10q LOH. The presence of 1p LOH was significantly associated with response to chemotherapy (p = 0.02). Median progression free survival (PFS) was 31 months for 1p intact patients and 118 months for the 1p LOH group (p = 0.014). Median PFS for 10q LOH patients was 31 and 118 months for patients with intact chromosome 10 (p = 0.016). 1p LOH is a predictor of response to chemotherapy and a good prognostic factor. 10q LOH is less common in oligodendroglial tumors but predicts for worse outcome. Molecular genotyping of oligodendroglial tumors is recommended as part of the standard diagnostic workup.     

Identification of genomic aberrations associated with shorter overall survival in patients with oligodendroglial tumors

Deletions on chromosomes 1p and 19q are associated with favorable prognosis in patients with oligodendroglial tumors. The aim of our study was to identify additional genomic aberrations linked to patient survival. We performed a genome-wide screen for genomic imbalances by comparative genomic hybridization on tumors from 70 patients, including 40 oligodendrogliomas, 30 oligoastrocytomas (21 WHO grade II tumors, 49 WHO grade III tumors). Data were correlated with overall patient survival (OS, median follow-up: 5.8 years). The most frequent aberrations were losses on chromosome 19q (64%), 1p (59%), 9p (26%), 4q (21%), 10q (19%), 18q (17%); gains on 7q (24%), 19p (19%), 7p (17%). In univariate analyses, combined 1p/19q and 19q loss were significantly associated with longer OS, and gains on 7, 8q, 19q, 20, losses on 9p, 10, 18q, Xp with shorter OS. Multivariate analyses showed the most significant prognostic factors for OS of patients with any oligodendroglial tumor to be WHO grade [odds ratio (OR) 8], 7p gain (OR 6), 9p loss (OR 3); for OS of patients with anaplastic tumors to be 7p gain (OR 10), 8q gain (OR 5), 18q loss (OR 3). Patients with anaplastic oligodendroglial tumors containing one or more prognostically unfavorable genomic aberration had a poor outcome independent of the 1p/19q status. In summary, we identified several independent genomic markers of shorter survival in patients with oligodendroglial tumors. Thus, molecular diagnostic testing, which is usually restricted to 1p/19q deletion analysis, may need to be refined by additionally assessing the prognostically unfavorable genomic aberrations identified.     

IDH‐mutated astrocytomas with 19q‐loss constitute a subgroup that confers better prognosis

IDH‐mutant gliomas are classified into astrocytic or oligodendroglial tumors by 1p/19q status in the WHO 2016 classification, with the latter presenting with characteristic morphology and better prognosis in general. However, the morphological and genetic features within each category are varied, and there might be distinguishable subtypes. We analyzed 170 WHO grade II‐IV gliomas resected in our institution. 1p/19q status was analyzed by microsatellite analysis, and genetic mutations were analyzed by next‐generation sequencing and Sanger sequencing. For validation, the Brain Lower Grade Glioma dataset of The Cancer Genome Atlas was analyzed. Of the 42 grade III IDH‐mutated gliomas, 12 were 1p‐intact/19q‐intact (anaplastic astrocytomas [AA]), 7 were 1p‐intact/19q‐loss (AA), and 23 showed 1p/19q‐codeletion (anaplastic oligodendrogliomas). Of the 88 IDH‐wild type glioblastomas (GBMs), 14 showed 1p‐intact/19q‐loss status. All of the seven 1p‐intact/19q‐loss AAs harbored TP53 mutation, but no TERT promotor mutation. All 19q‐loss AAs had regions presenting oligodendroglioma‐like morphology, and were associated with significantly longer overall survival compared to 19q‐intact AAs (P = .001). This tendency was observed in The Cancer Genome Atlas Lower Grade Glioma dataset. In contrast, there was no difference in overall survival between the 19q‐loss GBM and 19q‐intact GBM (P = .4). In a case of 19q‐loss AA, both oligodendroglial morphology and 19q‐loss disappeared after recurrence, possibly indicating correlation between 19q‐loss and oligodendroglial morphology. We showed that there was a subgroup, although small, of IDH‐mutated astrocytomas harboring 19q‐loss that present oligodendroglial morphology, and also were associated with significantly better prognosis compared to other 19q‐intact astrocytomas.     

Localization of common deletion regions on 1p and 19q in human gliomas and their association with histological subtype.

Allelic alterations of chromosomes 1 and 19 are frequent events in human diffuse gliomas and have recently proven to be strong predictors of chemotherapeutic response and prolonged survival in oligodendrogliomas (Cairncross et al., 1998; Smith et al., submitted). Using 115 human diffuse gliomas, we localized regions of common allelic loss on chromosomes 1 and 19 and assessed the association of these deletion intervals with glioma histological subtypes. Further, we evaluated the capacity of multiple modalities to detect these alterations, including loss of heterozygosity (LOH), fluorescence in situ hybridization (FISH), and comparative genomic hybridization (CGH). The correlation coefficients for detection of 1p and 19q alterations, respectively, between modalities were: 0.98 and 0.87 for LOH and FISH, 0.79 and 0.60 for LOH and CGH, and 0.79 and 0.53 for FISH and CGH. Minimal deletion regions were defined on 19q13.3 (D19S412-D19S596) and 1p (D1S468-D1S1612). Loss of the 1p36 region was found in 18% of astrocytomas (10/55) and in 73% (24/33) of oligodendrogliomas (P < 0.0001), and loss of the 19q13.3 region was found in 38% (21/55) of astrocytomas and 73% (24/33) of oligodendrogliomas (P = 0.0017). Loss of both regions was found in 11% (6/55) of astrocytomas and in 64% (21/33) of oligodendrogliomas (P < 0.0001). All gliomas with LOH on either 1p or 19q demonstrated loss of the corresponding FISH probe, 1p36 or 19q13.3, suggesting not only locations of putative tumor suppressor genes, but also a simple assay for assessment of 1p and 19q alterations as diagnostic and prognostic markers.     

Correlation of chromosomal imbalances by comparative genomic hybridization and expression of EGFR, PTEN, p53, and MIB-1 in diffuse gliomas

The histological subclassification of gliomas is increasingly assisted by the underlying molecular genetics which has major importance in guiding clinical management of the disease. However, the assessment of several molecular events for improving clinical care remains a challenge. Herein, we report on comparative genomic hybridization (CGH) and immunohistochemical (IHC) assessment of EGFR, PTEN, p53, and MIB-1 expression in 13 oligodendrogliomas (10 WHO grade II, 3 WHO grade III), one oligoastrocytoma (WHO grade III) and 23 high-grade astrocytomas (3 WHO grade III, 20 glioblastoma multiforme). The most frequent imbalances in oligodendroglial tumors including the oligoastrocytic case were, in decreasing order of frequency, +7q, -1p, and -4q and in astrocytomas +7q, -10q, +7p, -9p, -10p, +20q, and +20p. Some individual imbalances were associated with increasing numbers of chromosomal changes, that were +7q in both oligodendrogliomas and astrocytomas, and -9p, -10q, +20p, and +20q in astrocytomas. The markers p53 and MIB-1 were significantly higher expressed in astrocytomas than in oligodendrogliomas and expression levels of p53 and EGFR were inversely associated within the astrocytic group. In addition, p53 overexpression correlated positively with +7q and negatively with -1p in the oligodendroglial group whereas EGFR overexpression correlated positively with -1p in the oligodendroglial and positively with +7p and -10p in the astrocytic group. Short overall survival was significantly associated with +7p and -10q in astrocytomas. Collectively, these results contribute to the increasing clinical relevance of assessing tumor biological markers in gliomas.     

High rate of deletion of chromosomes 1p and 19q in insular oligodendroglial tumors

It has been reported recently that oligodendroglial tumors arising in the insula rarely harbor co-deletions of chromosomes 1p and 19q, a molecular signature which is associated with a good prognosis and increased responsiveness to radiation and chemotherapy compared with tumors in which 1p and/or 19q is intact. In the context of this claim, we analyzed a series of insular oligodendroglial tumors in order to determine the frequency of 1p/19q co-deletion in tumors arising in this region. We identified 14 insular cases operated on after 2003 in which testing for losses of 1p and 19q was performed. Of these cases, co-deletion of 1p and 19q occurred in eight (57%). Four (50%) of eight oligodendrogliomas and four (67%) of six oligoastrocytomas demonstrated 1p/19q co-deletions. Seven of the eight tumors with co-deletion of 1p/19q were WHO grade II gliomas. There were no statistical differences between tumors with 1p/19q co-deletion compared to those with 1p and/or 19q intact in terms of age, preoperative KPS, presenting symptoms, left versus right lateralization, tumor location (purely insular versus extension into frontal or temporal lobe), preoperative tumor size. There was a preponderance of females in the co-deletion group, and a greater average extent of resection. In contradistinction to previous reports, loss of 1p/19q occurs commonly in insular oligodendroglial tumors. With respect to 1p/19q, insular gliomas do not appear to be distinct from gliomas arising elsewhere in the brain.     

Prognostic significance of multiple genetic lesions on chromosomes 19, 10, and 17 in oligodendrogliomas

Patients diagnosed with oligodendrogliomas/oligoastrocytomas and with somatic loss of genes on chromosome 19q13.2-q13.3 survived for >5-6 years, a survival period typical of the tumors of oligodendroglial origin. One patient with oligoastrocytoma, harboring allelic loss on chromosome 10p in the tumor DNA, had a recurrence five years later with progression to anaplastic astrocytoma. However, another patient with oligoastrocytoma, whose tumor suffered multiple genetic lesions on chromosomes 19q13.2-13.3, 10q22-24, and 17p13.1 (a point mutation in the p53 gene), had two subsequent recurrences as anaplastic astrocytomas and a survival period of 29 months. Our data suggest that in tumors of oligodendroglial origin the inactivation of a tumor suppressor gene on chromosome 10, especially in conjunction with other genetic aberrations, is indicative of aggressive clinical course.     

Prognostic stratification of patients with anaplastic gliomas according to genetic profile

BACKGROUND: There is a need to improve the current, controversial, and poorly reproducible classification of anaplastic gliomas, which represent a highly heterogeneous entity in terms of survival. METHODS: The impact of the most common genetic alterations on survival was investigated based on 156 anaplastic gliomas: Among the patients who were included, the gender ratio was 1.32, the median age was 45.5 years (range, 20-83 years), and the median Karnofsky performance status was 70 (range, 40-100). Genetic analysis included a search for loss of heterozygosity (LOH) on chromosomes 1p and 19q; amplification of chromosomes 9p and 10q and of the epidermal growth factor receptor (EGFR), cyclin-dependent kinase 4 (CDK4) and mouse double-minute (MDM2) genes; and p53 expression. RESULTS: The median survival was 33.5 months, and the median progression-free survival was 15.8 months. In a univariate analysis, LOH on 1p and 19q was correlated with longer survival, whereas p53 expression, LOH on 9p, LOH on 10q, amplified EGFR, and deleted CDKN2A were correlated with shorter survival. LOH on 1p and 19q were associated with oligodendrogliomas, LOH on 10q was related to EGFR amplification, and LOH on 1p and 19q was mutually exclusive with EGFR amplification and LOH on 10q. In a multivariate analysis, the significant prognostic factors were age, histology, LOH on 1p and 19q, and P16/CDKN2A deletion. Recursive partitioning analysis (RPA) divided the whole group hierarchically into 3 distinct prognostic subgroups: Group A with 1p19q codeletion (median survival, 98 months), Group B with EGFR amplification (median survival, 17 months), and Group CC (median survival, 31 months), providing a basis for a genetically based prognostic subclassification for patients with Grade III gliomas. CONCLUSIONS: The search for 1p19q codeletion and EGFR receptor amplification provides a simple, clinically relevant prognostic subclassification of grade III gliomas.     

Differential proteome analysis of human gliomas stratified for loss of heterozygosity on chromosomal arms 1p and 19q

Combined deletion of chromosomal arms 1p and 19q is an independent prognostic marker in patients with oligodendroglial brain tumors, including oligodendrogliomas and oligoastrocytomas. However, the relevant genes in these chromosome arms and the molecular mechanisms underlying the prognostic significance of 1p/19q deletion are yet unknown. We used two-dimensional difference gel electrophoresis followed by mass spectrometry to perform a proteome-wide profiling of low-grade oligoastrocytomas stratified for the presence or absence of 1p/19q deletions. Thereby, we identified 22 different proteins showing differential expression in tumors with or without combined deletions of 1p and 19q. Four of the differentially expressed proteins, which are vimentin, villin 2 (ezrin), annexin A1, and glial fibrillary acidic protein, were selected for further analysis. Lower relative expression levels of these proteins in 1p/19q-deleted gliomas were confirmed at the protein level by Western blot analysis and immunohistochemistry. Furthermore, sequencing of sodium bisulfite–treated tumor DNA revealed more frequent methylation of 5′-CpG islands associated with the VIM and VIL2 genes in 1p/19q-deleted gliomas when compared with gliomas without these deletions. In summary, we confirm proteome-wide profiling as a powerful means to identify candidate biomarkers in gliomas. In addition, our data support the hypothesis that 1p/19q-deleted gliomas frequently show epigenetic down-regulation of multiple genes due to aberrant methylation of the 5′-CpG islands.     

Alterations of chromosome arms 1p and 19q as predictors of survival in oligodendrogliomas, astrocytomas, and mixed oligoastrocytomas.

PURPOSE: A recent report suggests that alterations of chromosome arms 1p and 19q are associated with chemotherapeutic response and overall survival in anaplastic oligodendroglioma patients treated with procarbazine, lomustine, and vincristine chemotherapy. We set out to further clarify the diagnostic and prognostic implications of these alterations in a broader set of diffuse gliomas, including astrocytic neoplasms and low-grade oligodendrogliomas. PATIENTS AND METHODS: Fluorescence in situ hybridization (FISH) signals from DNA probes mapping to 1p and 19q common deletion regions were enumerated in 162 diffuse gliomas (79 astrocytomas, 52 oligodendrogliomas, and 31 mixed oligoastrocytomas), collected as part of an ongoing prospective investigation of CNS tumors. RESULTS: The oligodendroglial phenotype was highly associated with loss of 1p (P =.0002), loss of 19q (P <.0001), and combined loss of 1p and 19q (P <.0001). Combined loss of 1p and 19q was identified as a univariate predictor of prolonged overall survival among patients with pure oligodendroglioma (log-rank, P =.03) and remained a significant predictor after adjusting for the effects of patient age and tumor grade (P <.01). This favorable association was not evident in patients with astrocytoma or mixed oligoastrocytoma. CONCLUSION: Combined loss of 1p and 19q is a statistically significant predictor of prolonged survival in patients with pure oligodendroglioma, independent of tumor grade. Given the lack of this association in patients with astrocytic neoplasms and the previously demonstrated chemosensitivity of oligodendrogliomas, a combined approach of histologic and genotypic assessment could potentially improve existing strategies for patient stratification and management.     

Morphologic and molecular genetic aspects of oligodendroglial neoplasms

Morphologic criteria for diagnosing oligodendrogliomas and for classifying them as well-differentiated (World Health Organization grade II) and anaplastic (World Health Organization grade III) are well recognized. Nevertheless, applying these guidelines to specific cases often reveals discrepancies among different observers. In addition, whether a given tumor also contains an astrocytic component may be debatable. Loss of heterozygosity studies have demonstrated that oligodendroglial neoplasms have a high incidence of loss of the 1p and 19q chromosomal arms. Although loss of heterozygosity for portions of 19q are sometimes seen in astrocytic neoplasms, these tumors seldom show complete loss of 19q accompanied by loss of 1p. Loss of 9p or homozygous deletion of the CDKN2 gene or both are associated with anaplastic oligodendrogliomas, whereas loss of 17p or TP53 gene mutations or both are frequent in astrocytomas, but rare in oligodendrogliomas. These observations suggest that molecular genetic parameters could provide an objective, reproducible framework for classifying oligodendroglial neoplasms.