title: O6-methylguanine DNA methyltransferase status determined by promoter methylation and immunohistochemistry in gliosarcoma and their clinical implications.
abstract: O(6)-methylguanine-DNA methyltransferase (MGMT) is known as a DNA repair protein, and loss of function in MGMT is related to an increase in survival in patients with malignant gliomas treated with alkylating agents. In the present study, we determined the status of MGMT using methylation-specific polymerase chain reaction (PCR) and immunohistochemistry on paraffin-embedded specimens in 12 human gliosarcomas, and these results were then related to overall survival (OS) and response to alkylating agents. The MGMT promoter was methylated in six patients. Immunostaining of MGMT was positive in 58.3% of patients. MGMT methylation status was correlated with immunostaining results in five patients (41.7%). The median OS and progression-free survival (PFS) of the whole population were 13.4 months [95% confidence interval (CI), 12.3-14.5 months] and 8.3 months (95% CI, 7.4-9.2 months), respectively. In patients with methylated MGMT promoter, median OS was 15.0 months, compared with 11.3 months in the unmethylated group. Median PFS of gliosarcoma patients was 10.3 months for the methylated group, whereas it was 7.3 months for the unmethylated group. On multivariate analysis, patients with methylated MGMT promoter had better prognosis than patients with unmethylated MGMT promoter with respect to OS and PFS (P = 0.045 and 0.034, respectively). However, there was no statistical significance between MGMT protein expression and survival. The results show that a significant fraction of gliosarcomas have MGMT promoter methylation and protein expression, and suggest that patient survival is associated with MGMT methylation status.
authors.affiliation: Department of Neurosurgery, Korea University Anam Hospital, Korea University College of Medicine, #126-1, 5-Ga, Anam-dong, Seongbuk-gu, Seoul, 136-705, Korea.
authors.forename: Shin-Hyuk
authors.initials: SH
authors.lastname: Kang
authors.forename: Kyung-Jae
authors.initials: KJ
authors.lastname: Park
authors.forename: Chae-Yong
authors.initials: CY
authors.lastname: Kim
authors.forename: Mi Ok
authors.initials: MO
authors.lastname: Yu
authors.forename: Chul-Kee
authors.initials: CK
authors.lastname: Park
authors.forename: Sung-Hye
authors.initials: SH
authors.lastname: Park
authors.forename: Yong-Gu
authors.initials: YG
authors.lastname: Chung
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000494:pharmacology; D001932:Brain Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000235:genetics*; D045643:DNA Repair Enzymes / Q000235:genetics*; D004273:DNA, Neoplasm / Q000235:genetics; D005260:Female; D018316:Gliosarcoma / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics*; D015996:Survival Rate; D016896:Treatment Outcome; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; D025521:Tumor Suppressor Proteins; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes