Methylation of selected CpGs in the humanO6-methylguanine-DNA methyltransferase promoter region as a marker of gene silencing

Autor: Sherie R. Howell, Rebecca P. Danam, Thomas P. Brent, Xilin C. Qian
Rok vydání: 1999
Předmět:
Zdroj: Molecular Carcinogenesis. 24:85-89
ISSN: 1098-2744
0899-1987
DOI: 10.1002/(sici)1098-2744(199902)24:2<85::aid-mc2>3.0.co;2-c
Popis: O6-Methylguanine-DNA methyltransferase (MGMT) is a major determinant of susceptibility to methylating carcinogens and of tumor resistance to anticancer methylating and chloroethylating drugs. The silencing of MGMT expression that occurs in 20–30% of human tumor lines is tightly linked to methylation within the MGMT gene 5′ CpG island. Previous studies on a very limited number of cell lines showed that such methylation was uneven, with hot-spots where methylation almost invariably occurred and intervening regions with very low incidences of methylation. To ascertain if such hot-spot methylation is in fact a ubiquitous hallmark of MGMT-silenced cells, we determined the methylation status of selected hot-spot CpGs in an extensive panel of MGMT-expressing and -silenced cell lines and xenografts. Using two simple and rapid bisulfite–polymerase chain reaction–based assays, we confirmed that in MGMT-silenced cells, methylation occurred at these sites whereas it was essentially absent in MGMT-expressing cells. Mol. Carcinog. 24:85–89, 1999. © 1999 Wiley-Liss, Inc.
Databáze: OpenAIRE
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