Screening for genomic fragments that are methylated specifically in colorectal carcinoma with a methylated MLH1 promoter.
A subset of colorectal carcinomas (CRCs) is associated with microsatellite instability (MSI) of the genome. Although extensive methylation of CpG islands within the promoter regions of DNA mismatch repair genes such as MLH1 is thought to play a central role in tumorigenesis for MSI-positive sporadic CRCs, it has been obscure whether such aberrant epigenetic regulation occurs more widely and affects other cancer-related genes in vivo. Here, by using methylated CpG island amplification coupled with representational difference analysis (MCA-RDA), we screened genomic fragments that are selectively methylated in CRCs positive for MLH1 methylation, resulting in the identification of hundreds of CpG islands containing genomic fragments. Methylation status of such CpG islands was verified for 28 genomic clones in 8 CRC specimens positive for MLH1 methylation and the corresponding paired normal colon tissue as well as in 8 CRC specimens negative for methylation. Many of the CpG islands were preferentially methylated in the MLH1 methylation-positive CRC specimens, although methylation of some of them was more widespread. These data provide insights into the complex regulation of the methylation status of CpG islands in CRCs positive for MSI and MLH1 methylation.
Koinuma
Koji
K
Division of Functional Genomics, Jichi Medical School, Tochigi 329-0498, Japan.
Kaneda
Ruri
R
Toyota
Minoru
M
Yamashita
Yoshihiro
Y
Takada
Shuji
S
Choi
Young Lim
YL
Wada
Tomoaki
T
Okada
Masaki
M
Konishi
Fumio
F
Nagai
Hideo
H
Mano
Hiroyuki
H
D048868:Adaptor Proteins, Signal Transducing; D000368:Aged; D000369:Aged, 80 and over; D055398:Bone Morphogenetic Protein 3; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics*; D003106:Colon / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000235:genetics*; D018899:CpG Islands / Q000235:genetics*; D019175:DNA Methylation; D004260:DNA Repair; D004273:DNA, Neoplasm / Q000235:genetics; D005260:Female; D005784:Gene Amplification; D015972:Gene Expression Regulation, Neoplastic; D042822:Genomic Instability; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D009687:Nuclear Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
D048868:Adaptor Proteins, Signal Transducing; C525757:BMP3 protein, human; D055398:Bone Morphogenetic Protein 3; D019485:Bone Morphogenetic Proteins; D002352:Carrier Proteins; D004273:DNA, Neoplasm; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D000070957:MutL Protein Homolog 1