title: Promoter hypermethylation and loss of CD133 gene expression in colorectal cancers.
abstract: OBJECTIVE
  To understand CD133 promoter hypermethylation and expression in 32 colorectal cancer cell lines.
  
  
  METHODS
  Nucleic acid was isolated from 32 colorectal cancer cell lines and CD133 expression levels were measured by reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR. Promoter methylation status of the CD133 gene was analyzed with a methylation-specific PCR after sodium-bisulfite modification and by clonal sequencing analysis. The correlation between expression and promoter methylation of CD133 gene was confirmed with treatment of 5-aza-2'-deoxycytidine.
  
  
  RESULTS
  We measured CD133 expression levels in 32 colorectal cancer cell lines. RT-PCR analysis showed undetectable or low levels of CD133 expression in 34.4% of cell lines. To verify the relation between CD133 expression and methylation status of the CD133 gene promoter in colorectal carcinogenesis, CD133 gene promoter hypermethylation was analyzed in 32 cancer cell lines. Promoter hypermethylation was detected in 13 (40.6%) of the cell lines using methylation specific-PCR and confirmed by bisulfite sequencing analysis. Treatment of 11 of the cell lines with the demethylation agent 5-aza-2'-deoxycytidine recovered CD133 expression in most of them.
  
  
  CONCLUSIONS
  Transcriptional repression of CD133 is caused by promoter hypermethylation of the CD133 CpG islands in some of colorectal cancer cell lines. The study may contribute to the understanding of the role of CD133 inactivation in the progression of colorectal cancers.
authors.affiliation: Laboratory of Cell Biology, Cancer Research Institute, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul 110-744, South Korea.
authors.forename: You-Kyung
authors.initials: YK
authors.lastname: Jeon
authors.forename: Sung-Hee
authors.initials: SH
authors.lastname: Kim
authors.forename: Seung-Ho
authors.initials: SH
authors.lastname: Choi
authors.forename: Kyung-Hee
authors.initials: KH
authors.lastname: Kim
authors.forename: Byong-Chul
authors.initials: BC
authors.lastname: Yoo
authors.forename: Ja-Lok
authors.initials: JL
authors.lastname: Ku
authors.forename: Jae-Gahb
authors.initials: JG
authors.lastname: Park
mesh_terms: D000071916:AC133 Antigen; D015703:Antigens, CD / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism; D018899:CpG Islands; D019175:DNA Methylation; D015972:Gene Expression Regulation, Neoplastic; D006023:Glycoproteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D006023:Glycoproteins; C000606023:PROM1 protein, human; D010455:Peptides