title: Loss of 5-hydroxymethylcytosine and intratumoral heterogeneity as an epigenomic hallmark of glioblastoma.
abstract: Glioblastoma (GBM) is the most malignant neoplasm with predominant astrocytic differentiation and the most frequent primary brain tumor of the adult. Here, we investigated 170 human GBM specimens deriving from 162 patients, as well as 66 healthy control tissue specimens deriving from 27 patients, and analyzed the amount of 5-hydroxymethylcytosine (5hmC) in GBMs compared to normal brain and tumor infiltration zones. Additionally, we correlated the amount of 5hmC with two different proliferation markers, Ki67 and H3S10p. Genetic characterization of GBMs enabled us to analyze the effect of isocitrate dehydrogenase 1 (IDH1) mutations, O6-methylguanin-DNA-methyltransferase (MGMT) promoter methylation, and loss of heterozygosity of chromosome 1p and 19q (LOH1p/19q) on 5hmC amount. We found that GBMs show a tremendous loss of 5hmC, and we observed that even the infiltration zones show reduced amounts of 5hmC. Interestingly, the amount of 5hmC was inversely proportional to the two investigated proliferation markers, Ki67 and H3S10p. Correlation of 5hmC amount and molecular genetic markers of GBMs showed that there are no correlations of 5hmC amount and IDH1 mutations, MGMT promoter methylation, and LOH1p/19q. Furthermore, we evaluated the intratumoral distribution of 5hmC in compact and infiltrating areas and found that the quantification of the 5hmC amount is a useful tool in evaluation of tumor infiltration. In summary, our data emphasize that GBMs show a disturbed hydroxymethylome that is disrupted by IDH1 independent pathways, and that loss of 5hmC shows astonishing intratumoral heterogeneity.
authors.affiliation: Center for Neuropathology and Prion Research (ZNP), Ludwig-Maximilians-University, Feodor-Lynen-Str. 23, Munich, D-81377, Germany. theo.kraus@med.uni-muenchen.de.
authors.forename: Theo F J
authors.initials: TF
authors.lastname: Kraus
authors.affiliation: Center for Neuropathology and Prion Research (ZNP), Ludwig-Maximilians-University, Feodor-Lynen-Str. 23, Munich, D-81377, Germany.
authors.forename: Gesa
authors.initials: G
authors.lastname: Kolck
authors.affiliation: Center for Neuropathology and Prion Research (ZNP), Ludwig-Maximilians-University, Feodor-Lynen-Str. 23, Munich, D-81377, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Greiner
authors.affiliation: Center for Neuropathology and Prion Research (ZNP), Ludwig-Maximilians-University, Feodor-Lynen-Str. 23, Munich, D-81377, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Schierl
authors.affiliation: Center for Neuropathology and Prion Research (ZNP), Ludwig-Maximilians-University, Feodor-Lynen-Str. 23, Munich, D-81377, Germany.
authors.forename: Virginie
authors.initials: V
authors.lastname: Guibourt
authors.affiliation: Center for Neuropathology and Prion Research (ZNP), Ludwig-Maximilians-University, Feodor-Lynen-Str. 23, Munich, D-81377, Germany.
authors.forename: Hans A
authors.initials: HA
authors.lastname: Kretzschmar
mesh_terms: D044503:5-Methylcytosine / Q000031:analogs & derivatives; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003596:Cytosine / Q000031:analogs & derivatives* / Q000378:metabolism; D019175:DNA Methylation / Q000235:genetics*; D015254:DNA Modification Methylases / Q000235:genetics*; D045643:DNA Repair Enzymes / Q000235:genetics*; D044127:Epigenesis, Genetic; D005260:Female; D005909:Glioblastoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D006657:Histones / Q000235:genetics; D006801:Humans; D007521:Isocitrate Dehydrogenase / Q000235:genetics*; D019394:Ki-67 Antigen / Q000235:genetics; D019656:Loss of Heterozygosity / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011379:Prognosis; D011401:Promoter Regions, Genetic; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: D006657:Histones; D019394:Ki-67 Antigen; D025521:Tumor Suppressor Proteins; C011865:5-hydroxymethylcytosine; D044503:5-Methylcytosine; D003596:Cytosine; D007521:Isocitrate Dehydrogenase; C543588:IDH1 protein, human; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes
keywords: 5-hydroxymethylome; 5hmC; Brain tumor; Epigenetic; GBM; Glioblastoma