title: Oligodendrogliomas lacking O6-methylguanine-DNA-methyltransferase expression.
abstract: O6-Methylguanine-DNA-Methyltransferase (MGMT) is a DNA repair protein considered to be a chemosensitivity predictor. We evaluated the immunohistochemical MGMT expression in 28 consecutive oligodendroglial tumors (21 oligodendrogliomas, 5 mixed oligoastrocytomas, and 2 glioblastomas with prominent oligodendroglial features; 13 treated with CCNU) and compared it with that of 13 glioblastomas. Twenty-six (93%) oligodendroglial tumors were MGMT-negative, 2 (7%) were MGMT-positive. Twelve (92%) patients treated with CCNU had MGMT-negative lesions and their median survival was 73 months; 1 patient had an MGMT-positive oligodendroglioma and is alive at 28 months. Three (23%) glioblastomas were MGMT-negative and 10 (77%) MGMT-positive. The lower MGMT expression in oligodendroglial tumors compared to glioblastomas (P < 0.05), which have different chemosensitivity, suggests a possible role of MGMT in the determination of chemoresistance. Nevertheless, the heterogeneous outcome of our MGMT-negative oligodendroglial tumors treated with CCNU, indicates that MGMT expression alone is insufficient to predict the response to alkylating drugs, presumably because of the numerous mechanisms involved.
authors.affiliation: Department of Human Pathology and Oncology, University of Florence, Italy. ambuccoliero@unifi.it
authors.forename: A M
authors.initials: AM
authors.lastname: Buccoliero
authors.forename: L
authors.initials: L
authors.lastname: Arganini
authors.forename: F
authors.initials: F
authors.lastname: Ammannati
authors.forename: P
authors.initials: P
authors.lastname: Gallina
authors.forename: N
authors.initials: N
authors.lastname: Di Lorenzo
authors.forename: P
authors.initials: P
authors.lastname: Mennonna
authors.forename: G L
authors.initials: GL
authors.lastname: Taddei
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001932:Brain Neoplasms / Q000235:genetics* / Q000473:pathology; D004260:DNA Repair; D019008:Drug Resistance, Neoplasm; D005260:Female; D020869:Gene Expression Profiling; D005909:Glioblastoma / Q000235:genetics* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009607:Nitrosourea Compounds / Q000494:pharmacology*; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000032:analysis* / Q000235:genetics*; D009837:Oligodendroglioma / Q000235:genetics* / Q000473:pathology; D016019:Survival Analysis
chemical_list: D000970:Antineoplastic Agents; D009607:Nitrosourea Compounds; D019853:O(6)-Methylguanine-DNA Methyltransferase