author_facet Möllemann, Maria
Wolter, Marietta
Felsberg, Jörg
Collins, V. Peter
Reifenberger, Guido
Möllemann, Maria
Wolter, Marietta
Felsberg, Jörg
Collins, V. Peter
Reifenberger, Guido
author Möllemann, Maria
Wolter, Marietta
Felsberg, Jörg
Collins, V. Peter
Reifenberger, Guido
spellingShingle Möllemann, Maria
Wolter, Marietta
Felsberg, Jörg
Collins, V. Peter
Reifenberger, Guido
International Journal of Cancer
Frequent promoter hypermethylation and low expression of the MGMT gene in oligodendroglial tumors
Cancer Research
Oncology
author_sort möllemann, maria
spelling Möllemann, Maria Wolter, Marietta Felsberg, Jörg Collins, V. Peter Reifenberger, Guido 0020-7136 1097-0215 Wiley Cancer Research Oncology http://dx.doi.org/10.1002/ijc.20575 <jats:title>Abstract</jats:title><jats:p>Allelic losses on the chromosome arms 1p and 19q have been associated with favorable response to chemotherapy and good prognosis in anaplastic oligodendroglioma patients, but the molecular mechanisms responsible for this relationship are as yet unknown. The DNA repair enzyme O<jats:sup>6</jats:sup>‐methylguanine DNA methyltransferase (MGMT) may cause resistance to DNA‐alkylating drugs commonly used in the treatment of anaplastic oligodendrogliomas and other malignant gliomas. We report on the analysis of 52 oligodendroglial tumors for <jats:italic>MGMT</jats:italic> promoter methylation, as well as mRNA and protein expression. Using sequencing of sodium bisulfite‐modified DNA, we determined the methylation status of 25 CpG sites within the <jats:italic>MGMT</jats:italic> promoter. In 46 of 52 tumors (88%), we detected <jats:italic>MGMT</jats:italic> promoter hypermethylation as defined by methylation of more than 50% of the sequenced CpG sites. Real‐time reverse transcription‐PCR showed reduced <jats:italic>MGMT</jats:italic> mRNA levels relative to non‐neoplastic brain tissue in the majority of tumors with hypermethylation. Similarly, immunohistochemical analysis showed either no or only small fractions of MGMT positive tumor cells. <jats:italic>MGMT</jats:italic> promoter hypermethylation was significantly more frequent and the percentage of methylated CpG sites in the investigated <jats:italic>MGMT</jats:italic> promoter fragment was significantly higher in tumors with loss of heterozygosity on chromosome arms 1p and 19q as compared to tumors without allelic losses on these chromosomes arms. Taken together, our data suggest that <jats:italic>MGMT</jats:italic> hypermethylation and low or absent expression are frequent in oligodendroglial tumors and likely contribute to the chemosensitivity of these tumors.</jats:p> Frequent promoter hypermethylation and low expression of the <i>MGMT</i> gene in oligodendroglial tumors International Journal of Cancer
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title Frequent promoter hypermethylation and low expression of the MGMT gene in oligodendroglial tumors
title_unstemmed Frequent promoter hypermethylation and low expression of the MGMT gene in oligodendroglial tumors
title_full Frequent promoter hypermethylation and low expression of the MGMT gene in oligodendroglial tumors
title_fullStr Frequent promoter hypermethylation and low expression of the MGMT gene in oligodendroglial tumors
title_full_unstemmed Frequent promoter hypermethylation and low expression of the MGMT gene in oligodendroglial tumors
title_short Frequent promoter hypermethylation and low expression of the MGMT gene in oligodendroglial tumors
title_sort frequent promoter hypermethylation and low expression of the <i>mgmt</i> gene in oligodendroglial tumors
topic Cancer Research
Oncology
url http://dx.doi.org/10.1002/ijc.20575
publishDate 2005
physical 379-385
description <jats:title>Abstract</jats:title><jats:p>Allelic losses on the chromosome arms 1p and 19q have been associated with favorable response to chemotherapy and good prognosis in anaplastic oligodendroglioma patients, but the molecular mechanisms responsible for this relationship are as yet unknown. The DNA repair enzyme O<jats:sup>6</jats:sup>‐methylguanine DNA methyltransferase (MGMT) may cause resistance to DNA‐alkylating drugs commonly used in the treatment of anaplastic oligodendrogliomas and other malignant gliomas. We report on the analysis of 52 oligodendroglial tumors for <jats:italic>MGMT</jats:italic> promoter methylation, as well as mRNA and protein expression. Using sequencing of sodium bisulfite‐modified DNA, we determined the methylation status of 25 CpG sites within the <jats:italic>MGMT</jats:italic> promoter. In 46 of 52 tumors (88%), we detected <jats:italic>MGMT</jats:italic> promoter hypermethylation as defined by methylation of more than 50% of the sequenced CpG sites. Real‐time reverse transcription‐PCR showed reduced <jats:italic>MGMT</jats:italic> mRNA levels relative to non‐neoplastic brain tissue in the majority of tumors with hypermethylation. Similarly, immunohistochemical analysis showed either no or only small fractions of MGMT positive tumor cells. <jats:italic>MGMT</jats:italic> promoter hypermethylation was significantly more frequent and the percentage of methylated CpG sites in the investigated <jats:italic>MGMT</jats:italic> promoter fragment was significantly higher in tumors with loss of heterozygosity on chromosome arms 1p and 19q as compared to tumors without allelic losses on these chromosomes arms. Taken together, our data suggest that <jats:italic>MGMT</jats:italic> hypermethylation and low or absent expression are frequent in oligodendroglial tumors and likely contribute to the chemosensitivity of these tumors.</jats:p>
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author Möllemann, Maria, Wolter, Marietta, Felsberg, Jörg, Collins, V. Peter, Reifenberger, Guido
author_facet Möllemann, Maria, Wolter, Marietta, Felsberg, Jörg, Collins, V. Peter, Reifenberger, Guido, Möllemann, Maria, Wolter, Marietta, Felsberg, Jörg, Collins, V. Peter, Reifenberger, Guido
author_sort möllemann, maria
container_issue 3
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container_title International Journal of Cancer
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description <jats:title>Abstract</jats:title><jats:p>Allelic losses on the chromosome arms 1p and 19q have been associated with favorable response to chemotherapy and good prognosis in anaplastic oligodendroglioma patients, but the molecular mechanisms responsible for this relationship are as yet unknown. The DNA repair enzyme O<jats:sup>6</jats:sup>‐methylguanine DNA methyltransferase (MGMT) may cause resistance to DNA‐alkylating drugs commonly used in the treatment of anaplastic oligodendrogliomas and other malignant gliomas. We report on the analysis of 52 oligodendroglial tumors for <jats:italic>MGMT</jats:italic> promoter methylation, as well as mRNA and protein expression. Using sequencing of sodium bisulfite‐modified DNA, we determined the methylation status of 25 CpG sites within the <jats:italic>MGMT</jats:italic> promoter. In 46 of 52 tumors (88%), we detected <jats:italic>MGMT</jats:italic> promoter hypermethylation as defined by methylation of more than 50% of the sequenced CpG sites. Real‐time reverse transcription‐PCR showed reduced <jats:italic>MGMT</jats:italic> mRNA levels relative to non‐neoplastic brain tissue in the majority of tumors with hypermethylation. Similarly, immunohistochemical analysis showed either no or only small fractions of MGMT positive tumor cells. <jats:italic>MGMT</jats:italic> promoter hypermethylation was significantly more frequent and the percentage of methylated CpG sites in the investigated <jats:italic>MGMT</jats:italic> promoter fragment was significantly higher in tumors with loss of heterozygosity on chromosome arms 1p and 19q as compared to tumors without allelic losses on these chromosomes arms. Taken together, our data suggest that <jats:italic>MGMT</jats:italic> hypermethylation and low or absent expression are frequent in oligodendroglial tumors and likely contribute to the chemosensitivity of these tumors.</jats:p>
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spelling Möllemann, Maria Wolter, Marietta Felsberg, Jörg Collins, V. Peter Reifenberger, Guido 0020-7136 1097-0215 Wiley Cancer Research Oncology http://dx.doi.org/10.1002/ijc.20575 <jats:title>Abstract</jats:title><jats:p>Allelic losses on the chromosome arms 1p and 19q have been associated with favorable response to chemotherapy and good prognosis in anaplastic oligodendroglioma patients, but the molecular mechanisms responsible for this relationship are as yet unknown. The DNA repair enzyme O<jats:sup>6</jats:sup>‐methylguanine DNA methyltransferase (MGMT) may cause resistance to DNA‐alkylating drugs commonly used in the treatment of anaplastic oligodendrogliomas and other malignant gliomas. We report on the analysis of 52 oligodendroglial tumors for <jats:italic>MGMT</jats:italic> promoter methylation, as well as mRNA and protein expression. Using sequencing of sodium bisulfite‐modified DNA, we determined the methylation status of 25 CpG sites within the <jats:italic>MGMT</jats:italic> promoter. In 46 of 52 tumors (88%), we detected <jats:italic>MGMT</jats:italic> promoter hypermethylation as defined by methylation of more than 50% of the sequenced CpG sites. Real‐time reverse transcription‐PCR showed reduced <jats:italic>MGMT</jats:italic> mRNA levels relative to non‐neoplastic brain tissue in the majority of tumors with hypermethylation. Similarly, immunohistochemical analysis showed either no or only small fractions of MGMT positive tumor cells. <jats:italic>MGMT</jats:italic> promoter hypermethylation was significantly more frequent and the percentage of methylated CpG sites in the investigated <jats:italic>MGMT</jats:italic> promoter fragment was significantly higher in tumors with loss of heterozygosity on chromosome arms 1p and 19q as compared to tumors without allelic losses on these chromosomes arms. Taken together, our data suggest that <jats:italic>MGMT</jats:italic> hypermethylation and low or absent expression are frequent in oligodendroglial tumors and likely contribute to the chemosensitivity of these tumors.</jats:p> Frequent promoter hypermethylation and low expression of the <i>MGMT</i> gene in oligodendroglial tumors International Journal of Cancer
spellingShingle Möllemann, Maria, Wolter, Marietta, Felsberg, Jörg, Collins, V. Peter, Reifenberger, Guido, International Journal of Cancer, Frequent promoter hypermethylation and low expression of the MGMT gene in oligodendroglial tumors, Cancer Research, Oncology
title Frequent promoter hypermethylation and low expression of the MGMT gene in oligodendroglial tumors
title_full Frequent promoter hypermethylation and low expression of the MGMT gene in oligodendroglial tumors
title_fullStr Frequent promoter hypermethylation and low expression of the MGMT gene in oligodendroglial tumors
title_full_unstemmed Frequent promoter hypermethylation and low expression of the MGMT gene in oligodendroglial tumors
title_short Frequent promoter hypermethylation and low expression of the MGMT gene in oligodendroglial tumors
title_sort frequent promoter hypermethylation and low expression of the <i>mgmt</i> gene in oligodendroglial tumors
title_unstemmed Frequent promoter hypermethylation and low expression of the MGMT gene in oligodendroglial tumors
topic Cancer Research, Oncology
url http://dx.doi.org/10.1002/ijc.20575