[Detection of O6-methylguanine-DNA methyltransferase promoter methylation in chemotherapy for glioma].
OBJECTIVE
Epigenetic silencing of the DNA repair gene, O6-methylguanine-DNA methyltransferase (MGMT), is associated with the therapeutic response to methylating agents. This study was to assess the value of detecting the promoter methylation of MGMT gene in chemotherapy for glioma.


METHODS
Methylation-specific PCR (MSP) was employed to detect MGMT promoter CpG island methylation in 39 samples of glioma taken from surgery. Western blot and immunohistochemistry were used to detect protein expression. MTT were employed to detect the sensitivity of two glioma cell lines to alkylating agents, ACNU and TMZ. The Kaplan-Meier curve was adopted to estimate the overall survival according to the methylation status of the MGMT promoter.


RESULTS
Methylation of MGMT promoter CpG island was detectable in 46.2% of glioma tissues, but not in any normal tissues. The expression rate of MGMT protein was 61.5%. The status of MGMT methylation status was association with the protein level of MGMT (P<0.05). The MGMT gene was demethylated in glioma cell line SHG-44 following 5-Aza-CdR treatment; the expression of MGMT protein was restored and the resistance of SHG44 cells to alkylating agents was reversed. The overall survival was higher in patients with methylated MGMT promoter than in those with unmethylated MGMT promoter (P<0.05).


CONCLUSIONS
The status of MGMT promoter CpG island methylation is closely correlated to MGMT protein expression and sensitivity of cells to alkylating agents in glioma. Detection of the methylated sequences of MGMT may be used as a predictive factor for the treatment of glioma.
Zheng
Chang-Qing
CQ
Department of Biochemistry and Molecular Biology, Institute of Transfusion Medicine, Academy of Military Medical Sciences, Beijing, 100850, P.R. China.
Ji
Shou-Ping
SP
Gong
Feng
F
Li
An-Ming
AM
Tai
Jun-Li
JL
Zhang
Yang-Pei
YP
D000293:Adolescent; D000328:Adult; D000368:Aged; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D001932:Brain Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation; D003606:Dacarbazine / Q000031:analogs & derivatives / Q000494:pharmacology; D000077209:Decitabine; D019008:Drug Resistance, Neoplasm; D005260:Female; D005500:Follow-Up Studies; D005910:Glioma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015376:Nimustine / Q000494:pharmacology; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D015996:Survival Rate; D000077204:Temozolomide; D055815:Young Adult
D000964:Antimetabolites, Antineoplastic; D018906:Antineoplastic Agents, Alkylating; D015376:Nimustine; D000077209:Decitabine; D003606:Dacarbazine; D019853:O(6)-Methylguanine-DNA Methyltransferase; D001374:Azacitidine; D000077204:Temozolomide