BACKGROUND: Mixed gliomas, such as oligoastrocytomas (OA), anaplastic oligoastrocytomas, and glioblastomas (GBMs) with an oligodendroglial component (GBMO) are defined as tumors composed of a mixture of two distinct neoplastic cell types, astrocytic and oligodendroglial. Recently, mutations ATRX and TP53, and codeletion of 1p/19q are shown to be genetic hallmarks of astrocytic and oligodendroglial tumors, respectively. Subsequent molecular analyses of mixed gliomas preferred the reclassification to either oligodendroglioma or astrocytoma. This study was designed to apply genetically integrated diagnostic criteria to mixed gliomas and determine usefulness and prognostic value of new classification in Korean patients. METHODS: Fifty-eight cases of mixed OAs and GBMOs were retrieved from the pathology archives of Seoul National University Hospital from 2004 to 2015. Reclassification was performed according to genetic and immunohistochemical properties. Clinicopathological characteristics of each subgroup were evaluated. Overall survival was assessed and compared between subgroups. RESULTS: We could reclassify all mixed OAs and GBMOs into either astrocytic or oligodendroglial tumors. Notably, 29 GBMOs could be reclassified into 11 cases of GBM, IDH-mutant, 16 cases of GBM, IDH-wildtype, and two cases of anaplastic oligodendroglioma, IDH mutant. Overall survival was significantly different among these new groups (p<.001). Overall survival and progression-free survival were statistically better in gliomas with IDH mutation, ATRX mutation, no microscopic necrosis, and young patient age (cut off, 45 years old). CONCLUSIONS: Our results strongly suggest that a genetically integrated diagnosis of glioma better reflects prognosis than former morphology-based methods.
Astrocytoma ; Classification ; Diagnosis ; Disease-Free Survival ; Genetics ; Glioblastoma ; Glioma ; Humans ; Necrosis ; Oligodendroglioma ; Pathology ; Prognosis ; Seoul

OBJECTIVETo study the gene expression profiles of oligodendrogliomas with gene cDNA array.

METHODS(32)P tagged cDNA probes converted from the total RNA, which had been extracted from 2 fresh samples of oligodendroglioma and 1 of normal brain tissue, were hybridized with the Atlas array. After washing the membranes, the autoradiography was performed and the autoradiograms were analyzed through the special software.

RESULTSAs compared to the normal brain tissue, there were 63 co-upregulated genes and 4 co-downregulated genes in these 2 tumor samples. However, a significant quantitative difference existed between them. The expression trend of some genes differed from the known information.

CONCLUSIONcDNA array is effective for studying the gene expression profiles of oligodendrogliomas and provides new information for the further research on their molecular mechanisms.

Brain Neoplasms ; genetics ; pathology ; Gene Expression ; Gene Expression Profiling ; Humans ; Oligodendroglioma ; genetics ; pathology ; Oligonucleotide Array Sequence Analysis ; methods ; Reverse Transcriptase Polymerase Chain Reaction

OBJECTIVETo study the status of loss of heterozygosity (LOH) of chromosome 1p/19q and p53 protein expression in oligodendroglioma, as compared to astrocytoma.

METHODSOne hundred and ninety-one cases of glioma of different histologic types and grades, including 116 cases of low-grade of oligodendroglioma (86 paraffin-embedded and 30 fresh tissues), 45 cases of anaplastic oligodendroglioma (all paraffin-embedded tissues) and 30 cases of astrocytoma of various grades (all paraffin-embedded tissues), were enrolled into the study. The LOH of chromosome 1p/19q was investigated by polymerase chain reaction (PCR)-based microsatellite analysis. The p53 protein expression was demonstrated by immunohistochemical staining.

RESULTSThe rates of 1p loss, 19q loss and 1p/19q loss were 69.8%, 64%, and 57.0% respectively in the 86 paraffin-embedded low-grade oligodendroglioma samples, as compared to 71.1%, 60.0% and 55.6% respectively in the 45 paraffin-embedded anaplastic oligodendroglioma samples. There was no difference of LOH of 1p/19q between low-grade oligodendroglioma and anaplastic oligodendroglioma (P>0.05). In the 30 cases of low-grade oligodendroglioma with fresh tissues available, the rates of 1p loss, 19q loss and 1p/19q loss were 70.0%, 63.3% and 60.0% respectively. The LOH of 1p/19q between paraffin-embedded and fresh samples was not statistically significant (P>0.05). In the 30 cases of astrocytoma, the rates of 1p loss, 19q loss and 1p/19q loss were 23.3%, 33.3% and 20.0% respectively, which were significantly less than those in oligodendroglioma (P<0.05). The expression of p53 protein was significantly lower in low-grade oligodendroglioma (8.1%) than in anaplastic oligodendroglioma (31.1%, P=0.007). The expression of p53 protein in oligodendroglioma was also lower than in astrocytoma (P=0.001). Furthermore, p53 protein expression negatively correlated with 1p/19q loss in anaplastic oligodendroglioma (P<0.05).

CONCLUSIONSBoth paraffin-embedded and fresh tissues are suitable for analysis of LOH of chromosome 1p/19q. Oligodendroglioma demonstrates a higher frequency of LOH of chromosome 1p/19q and lower expression of p53 protein than astrocytoma. The LOH of chromosome 1p/19q negatively correlates with the expression of p53 protein. These parameters have both diagnostic and prognostic values.

Adolescent ; Adult ; Aged ; Astrocytoma ; genetics ; metabolism ; Brain Neoplasms ; genetics ; metabolism ; pathology ; Child ; Chromosomes, Human, Pair 1 ; Chromosomes, Human, Pair 19 ; Female ; Humans ; Loss of Heterozygosity ; Male ; Middle Aged ; Oligodendroglioma ; genetics ; metabolism ; pathology ; Paraffin Embedding ; Tumor Suppressor Protein p53 ; metabolism ; Young Adult

The current World Health Organization classification system of primary brain tumors is solely based on morphologic criteria. However, there is accumulating evidence that tumors with similar histology have distinct molecular signatures that significantly impact treatment response and survival. Recent practice-changing clinical trials have defined a role for routine assessment of O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation in glioblastoma patients, especially in the elderly, and 1p and 19q codeletions in patients with anaplastic glial tumors. Recently discovered molecular alterations including mutations in IDH-1/2, epidermal growth factor receptor (EGFR), and BRAF also have the potential to become targets for future drug development. This article aims to summarize current knowledge on the molecular biology of high-grade gliomas relevant to daily practice.
Aged ; Brain Neoplasms ; genetics ; metabolism ; pathology ; Chromosome Deletion ; DNA Methylation ; DNA Modification Methylases ; genetics ; metabolism ; DNA Repair Enzymes ; genetics ; metabolism ; Glioblastoma ; genetics ; metabolism ; pathology ; Glioma ; genetics ; metabolism ; pathology ; Humans ; Isocitrate Dehydrogenase ; genetics ; metabolism ; Neoplasm Grading ; Oligodendroglioma ; genetics ; metabolism ; pathology ; Point Mutation ; Promoter Regions, Genetic ; Receptor, Epidermal Growth Factor ; metabolism ; Tumor Suppressor Proteins ; genetics ; metabolism

Allelic loss of the short arm of chromosome 1 has been observed frequently in a wide spectrum of cancers, most frequently in oligodendroglioma. In our previous studies, we evaluated 177 oligodendroglial tumor samples and identified the AJAP1 gene (formerly Shrew1) in the consensus region of deletion. AJAP1 is a transmembrane protein found in adheren junctions and functions to inhibit glioma cell adhesion and migration. Whereas a putative tumor suppressor gene, we did not detect AJAP1 gene mutations. In subsequent studies, we found that AJAP1 was underexpressed in oligodendrogliomas relative to normal brain tissues. Bioinformatic analysis revealed the presence of CpG islands in the promoter of AJAP1. Methylation analysis of the AJAP1 promoter identified hypermethylation in 21% of oligodendrogliomas (n =27), and the degree of methylation correlated with low levels of AJAP1 expression (P = 0.045). The AJAP1 promoter was also highly methylated in a wide spectrum of cell lines (n = 22), including cell lines of glioblastoma. Analysis of the National Cancer Institute's REMBRANDT dataset, which contains 343 glioma samples, indicated that low AJAP1 gene expression was associated with decreased survival. Thus, both genetic (gene deletion) and epigenetic alterations (promoter methylation) are likely mechanisms that inactivate the putative tumor suppressor AJAP1 in gliomas, which contributes to poor prognosis.
Astrocytoma ; genetics ; metabolism ; pathology ; Cell Adhesion Molecules ; genetics ; metabolism ; Cell Line, Tumor ; Central Nervous System Neoplasms ; genetics ; metabolism ; pathology ; CpG Islands ; genetics ; DNA Methylation ; Down-Regulation ; Gene Deletion ; Glioblastoma ; genetics ; metabolism ; pathology ; Humans ; Oligodendroglioma ; genetics ; metabolism ; pathology ; Promoter Regions, Genetic ; genetics ; Survival Rate

OBJECTIVETo study the correlation of loss of heterozygosity (LOH) on chromosome 1p and 19q with the expression of MGMT, p53 and Ki-67 proteins in gliomas.

METHODSOne hundred and forty six cases of gliomas (45 oligodendrogliomas, 42 oligodendroastrocytomas, and 59 astrocytomas) were included in this study. Their tissue and blood samples were retrospectively analyzed by PCR-denaturing high-performance liquid chromatography (DHPLC) for 1p and 19q status and by immunohistochemistry for MGMT, p53 and Ki-67 expression patterns. The correlation among them and with clinicopathological characteristics were analyzed by chi-square test and t-test.

RESULTSIn the oligodendrogliomas, the positive rate of 1p LOH was 59.8%, significantly higher than 33.9% in astrocytomas (P = 0.002), and 1p and 19q LOH was 42.5%, significantly higher than 16.9% in astrocytomas (P = 0.001). Combined with LOH on 1p and 19q, low MGMT expression (65.5%), and high Ki-67 expression (54%) were more frequent in oligodendrogliomas, whereas high p53 expression was more frequent in astrocytomas and mixed tumors (75.2%). 1p LOH (72.5%) and low MGMT (87.5%) expressions were more frequent in grade II oligodendrogliomas, whereas high expressions of p53 (83.0%) and Ki-67 (76.6%) were more frequent in grade III oligodendrogliomas. In addition, high Ki-67 expression was more frequent in grade III astrocytomas. LOH on 1p and 19q LOH was more frequent in nontemporal oligodendrogliomas (55.6%) than that in temporal ones (22.2%, P = 0.002). Non-random associations were found between LOH 1p and 19q LOH, MGMT and p53 protein expressions, and MGMT and Ki-67 protein expressions (all P < 0.05), whereas mutual exclusions were found between LOH on 1p and 19q and p53 expression, and LOH 1p and Ki-67 expression.

CONCLUSIONSThere is a significant interrelationship of the investigated molecular markers and clinicopathological features of gliomas, which support a promising role of molecular markers in guiding diagnostic assessment and clinical management of gliomas.

Adolescent ; Adult ; Aged ; Astrocytoma ; genetics ; metabolism ; pathology ; Brain Neoplasms ; genetics ; metabolism ; pathology ; Child ; Chromosomes, Human, Pair 1 ; genetics ; Chromosomes, Human, Pair 19 ; genetics ; Female ; Glioma ; genetics ; metabolism ; pathology ; Humans ; Ki-67 Antigen ; metabolism ; Loss of Heterozygosity ; Male ; Middle Aged ; O(6)-Methylguanine-DNA Methyltransferase ; metabolism ; Oligodendroglioma ; genetics ; metabolism ; pathology ; Retrospective Studies ; Tumor Suppressor Protein p53 ; metabolism ; Young Adult

Using the methods of restriction fragment length polymorphism (RFLP) and single strand conformation polymorphism (SSCP) analyses, we have examined 33 cases of human gliomas with various malignant grades to detect the deletions of putative tumor suppressor gene loci, chromosome 10, 13q(retinoblastoma gene, Rb), 17p, and p53 mutation. We observed loss of heterozygosity (LOH) at loci on chromosome 10 (36%), 13q(Rb) (54%), and 17p(50%) in malignant gliomas. There, however was no allelic loss on chromosome 10 and 17p in low-grade gliomas. Rb gene deletions were seen in low-grade gliomas, including oligodendroglioma and ependymoma. This finding suggests that Rb inactivation may be an early genetic event in the development and progression of gliomas. We correlated the results of LOH on chromosome 17p and p53 mutation. Among the 8 cases which showed LOH on chromosome 17p, only three cases (38%) revealed p53 mutations. Low incidence of p53 mutations in cases with chromosome 17p deletions suggests that some other tumor suppressor genes may be located on chromosome 17p.
Astrocytoma/genetics/pathology ; Base Sequence ; Brain Neoplasms/*genetics/pathology ; *Chromosomes, Human, Pair 10 ; *Chromosomes, Human, Pair 13 ; *Chromosomes, Human, Pair 17 ; Comparative Study ; *Gene Deletion ; *Genes, Retinoblastoma ; *Genes, p53 ; Glioma/*genetics/pathology ; Heterozygote ; Human ; Molecular Sequence Data ; *Mutation ; Oligodendroglioma/genetics/pathology ; Polymorphism, Restriction Fragment Length ; Polymorphism, Single-Stranded Conformational

Alpha-internexin (INA) is a proneuronal gene-encoding neurofilament interacting protein. INA is overexpressed mostly in oligodendroglial phenotype gliomas, is related to 1p/19q codeletion, and is a favorable prognostic marker. We studied INA expression in oligodendrogliomas (ODGs) and glioblastomas (GBMs) to verify its association with several molecular phenotypes, 1p/19q codeletion, and epidermal growth-factor-receptor (EGFR) amplification. A total of 230 low- and high-grade ODG and GBM cases was analyzed for INA expression by immunohistochemical staining; and 1p/19q and EGFR gene status was examined by fluorescence in-situ hybridization. INA was positive in 80.3% of ODGs and in 34.3% of GBMs. 1p/19q codeletion was detected in 77.0% of ODGs and 5.5% of GBMs. INA and 1p/19q codeletion were strongly correlated (P < 0.001). The specificity of INA expression for 1p/19q codeletion was 70.8%, while sensitivity was 100%; positive predictive value was 72.5%, and negative predictive value was 29.2% in all 228 tumors. INA expression was correlated with better progression-free survival (PFS) and overall survival (OS) (P = 0.001). In conclusion, INA expression has high specificity and sensitivity to predict 1p/19q codeletion, and it is well correlated with PFS of both ODGs and GBMs. Therefore, INA expression could be a simple, reliable, and favorable prognostic and surrogate marker for 1p/19q codeletion and long term survival.
Adult ; Brain Neoplasms/*metabolism/mortality/pathology ; Chromosomes, Human, Pair 1 ; Chromosomes, Human, Pair 19 ; Female ; Gene Deletion ; Glioblastoma/*metabolism/mortality/pathology ; Humans ; Immunohistochemistry ; In Situ Hybridization, Fluorescence ; Intermediate Filament Proteins/genetics/*metabolism ; Kaplan-Meier Estimate ; Male ; Middle Aged ; Oligodendroglioma/*metabolism/mortality/pathology ; Phenotype ; Predictive Value of Tests ; Prognosis ; Receptor, Epidermal Growth Factor/genetics/metabolism