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Age-related differences in 1p and 19q deletions in oligodendrogliomas.

ABSTRACT: BACKGROUND: Recent reports indicate that anaplastic oligodendrogliomas frequently show allelic losses on chromosome arms 1p and 19q, and that these deletions are associated with better chemotherapeutic response and overall patient survival. Because of the diversified genetic makeup of the population and the centralized provincial referral system for brain tumor patients in Manitoba, the epidemiological features of such tumors sometimes differ from the published data acquired from non-community based settings. In this study, we assessed the prevalence of allelic deletions for chromosome arms 1p and 19q in anaplastic and in low-grade oligodendrogliomas in the Manitoba population. METHODS: Loss of heterozygosity (LOH) analysis of brain tumors was carried out using 4 microsatellite markers (D1S508, D1S2734, D19S219 and D19S412) and a PCR based assay. The tumors were consecutively acquired during the period September 1999-March 2001 and a total of 63 tumors were assessed. RESULTS: We found that allelic loss of chromosome 1p and 19q was higher in oligodendrogliomas than in other diffuse gliomas and that for anaplastic oligodendrogliomas, younger patients exhibited significantly more deletions than older patients (>60 years of age). CONCLUSIONS: These studies suggest that age may be a factor in the genetic alterations of oligodendrogliomas. In addition, these studies demonstrate that this assay can easily be carried out in a cost-effective manner in a small tertiary center.

SUBMITTER: Myal Y

PROVIDER: S-EPMC317335 | biostudies-literature | 2003 Dec

REPOSITORIES: biostudies-literature

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Age-related differences in 1p and 19q deletions in oligodendrogliomas.

Myal Yvonne Y Del Bigio Marc R MR Rhodes Roy H RH

BMC clinical pathology 20031211 1

BACKGROUND: Recent reports indicate that anaplastic oligodendrogliomas frequently show allelic losses on chromosome arms 1p and 19q, and that these deletions are associated with better chemotherapeutic response and overall patient survival. Because of the diversified genetic makeup of the population and the centralized provincial referral system for brain tumor patients in Manitoba, the epidemiological features of such tumors sometimes differ from the published data acquired from non-community b ...[more]

PMID: 14670088

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Project description:Approximately 50-80% of oligodendrogliomas demonstrate a combined loss of chromosome 1p and 19q. Chromosome 1p/19q deletion, appearing early in tumorigenesis, is associated with improved clinical outcomes, including response to chemotherapy and radiation. Although many hypotheses have been proposed, the molecular mechanisms underlying improved clinical outcomes with 1p/19q deletion in oligodendrogliomas have not been characterized fully. To investigate the molecular differences between oligodendrogliomas, we employed an unbiased proteomic approach using microcapillary liquid chromatography mass spectrometry, along with a quantitative technique called isotope-coded affinity tags, on patient samples of grade II oligodendrogliomas. Following conventional biochemical separation of pooled tumor tissue from five samples of undeleted and 1p/19q deleted grade II oligodendrogliomas into nuclei-, mitochondria-, and cytosol-enriched fractions, relative changes in protein abundance were quantified. Among the 442 total proteins identified, 163 nonredundant proteins displayed significant changes in relative abundance in at least one of the three fractions between oligodendroglioma with and without 1p/19q deletion. Bioinformatic analyses of differentially regulated proteins supported the potential importance of metabolism and invasion/migration to the codeleted phenotype. A subset of altered proteins, including the pro-invasive extracellular matrix protein BCAN, was further validated by Western blotting as candidate markers for the more aggressive undeleted phenotype. These studies demonstrate the utility of proteomic analysis to identify candidate biological motifs and molecular mechanisms that drive differential malignancy related to 1p19q phenotypes. Future analysis of larger patient samples are warranted to further refine biomarker panels to predict biological behavior and assist in the identification of deleted gene products that define the 1p/19q phenotype.

Project description:The molecular genetic alterations of oligodendroglial tumors and mixed gliomas of the central nervous system were studied in a series of 37 cases (8 oligodendrogliomas, 13 anaplastic oligodendrogliomas, 8 oligoastrocytomas, and 8 anaplastic oligoastrocytomas). A total of 180 polymorphic loci and 5 nonpolymorphic gene loci, distributed over all chromosomes, were examined by restriction fragment length polymorphism analysis. Loss of heterozygosity was most frequently observed for loci on 19q with a commonly deleted region at 19q13.2-q13.4 distal to the CYP2a gene and proximal to the D19S22 locus. The incidence of allelic loss on 19q was particularly high (81%) in oligodendroglial tumors and equal to 31% in mixed gliomas. More than 75% of the tumors with allelic deletions on 19q also showed loss of heterozygosity for loci on 1p with one tumor showing only loss of alleles distal to the NGFB gene (1p13-pter). Seven (19%) tumors had lost alleles from 17p with the deleted region including the TP53 tumor suppressor gene in all cases. Sequencing of the TP53 transcripts from exons 2 to 10, however, did not reveal mutations of the remaining allele in any of these tumors. Anaplastic oligodendrogliomas and anaplastic oligoastrocytomas demonstrated an increased incidence of additional allelic losses involving most frequently chromosomes 9p and 10. Gene amplification was detected in two anaplastic tumors, affecting the epidermal growth factor receptor gene in both cases, with additional amplification of the renin gene at 1q32 in one of these cases. In total our results indicate both differences and similarities between the molecular genetic alterations in tumors with oligodendroglial and astrocytic differentiation. The loss of genetic information from 19q and 1p as well as the rarity of TP53 mutations in oligodendroglial tumors suggests that the early events in their oncogenesis are distinct from those associated with astrocytic tumors. However, similarities are indicated by the allelic losses on 9p and 10 in the anaplastic tumors, suggesting the utilization of common pathways of progression.

Dataset Information

Age-related differences in 1p and 19q deletions in oligodendrogliomas.

Publications

Age-related differences in 1p and 19q deletions in oligodendrogliomas.

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