title: Aberrant promoter methylation of multiple genes in oligodendrogliomas and ependymomas.
abstract: Promoter hypermethylation represents a primary mechanism in the inactivation of tumor suppressor genes during tumorigenesis. To determine the frequency and timing of hypermethylation during carcinogenesis of nonastrocytic tumors, we analyzed promoter methylation status of 10 tumor-associated genes in a series of 41 oligodendrogliomas (22 World Health Organization [WHO] grade II; 13 WHO grade III; 6 WHO grade II-III oligoastrocytomas) and 7 WHO grade II-III ependymomas, as well as 2 nonneoplastic brain samples, by a methylation-specific polymerase chain reaction. Aberrant CpG island methylation was detected in 9 of 10 genes analyzed, and all but one sample displayed anomalies in at least one gene. The frequencies of hypermethylation for the 10 genes were as follows, in oligodendrogliomas and ependymomas, respectively: 80% and 28% for MGMT; 70% and 28% for GSTP1; 66% and 57% for DAPK; 44% and 28% for TP14(ARF); 39% and 0% for THBS1; 24% and 28% for TIMP3; 24% and 14% for TP73; 22% and 0% for TP16(INK4A); 3% and 14% for RB1; and 0% in both neoplasms for TP53. No methylation of these genes was detected in normal brain tissue samples. We conclude that a high frequency of aberrant methylation of the 5' CpG island of the MGMT, GSTP1, TP14(ARF), THBS1, TIMP3, and TP73 genes is observed in nonastrocytic neoplasms. This aberration seems to occur early in the carcinogenesis process (it is already present in the low-grade forms), although in some instances (DAPK, THBS1, and TP73) it appears also associated with the genesis of anaplastic forms.
authors.affiliation: Departmento de Cirurgía Experimental, Laboratorio de Oncogenética Molecular, Hospital Universitario La Paz, Madrid, Spain.
authors.forename: M Eva
authors.initials: ME
authors.lastname: Alonso
authors.forename: M Josefa
authors.initials: MJ
authors.lastname: Bello
authors.forename: Pilar
authors.initials: P
authors.lastname: Gonzalez-Gomez
authors.forename: Dolores
authors.initials: D
authors.lastname: Arjona
authors.forename: Jesus
authors.initials: J
authors.lastname: Lomas
authors.forename: Jose M
authors.initials: JM
authors.lastname: de Campos
authors.forename: Alberto
authors.initials: A
authors.lastname: Isla
authors.forename: Jose L
authors.initials: JL
authors.lastname: Sarasa
authors.forename: Juan A
authors.initials: JA
authors.lastname: Rey
mesh_terms: D000328:Adult; D018899:CpG Islands; D019175:DNA Methylation; D004806:Ependymoma / Q000235:genetics*; D005260:Female; D019942:Genes, p16; D016158:Genes, p53; D006801:Humans; D019656:Loss of Heterozygosity; D008297:Male; D008875:Middle Aged; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics; D009837:Oligodendroglioma / Q000235:genetics*; D011401:Promoter Regions, Genetic; D025803:Tumor Suppressor Protein p14ARF / Q000235:genetics
chemical_list: D025803:Tumor Suppressor Protein p14ARF; D019853:O(6)-Methylguanine-DNA Methyltransferase