Inactivation of p57KIP2 by regional promoter hypermethylation and histone deacetylation in human tumors.
To clarify the role of DNA methylation in the silencing of the expression of cyclin-dependent kinase inhibitor p57KIP2 seen in certain tumors, we investigated the methylation status of its 5' CpG island in various tumor cell lines and primary cancers. Dense methylation of the region around the transcription start site was detected in 1 out of 10 colorectal, 2 out of 8 gastric, and 6 out of 14 hematopoietic tumor cell lines and in 5 out of 35 (14%) gastric, 6 out of 20 (30%) hepatocellular, and 2 out of 18 (11%) pancreatic cancers; 7 out of 25 (28%) acute myeloid leukemia cases also showed methylation of the p57KIP2 gene, which strongly correlated with the CpG island methylator phenotype (P<0.001). Detailed mapping revealed that dense methylation of the region around the transcription start site (-300 to +400), but not of the edges of the CpG island, was closely associated with gene silencing. 5-aza-2'-deoxycytidine, a methyltransferase inhibitor, restored expression of p57KIP2, and chromatin immunoprecipitation using anti-histone H3 and H4 antibodies showed histone to be deacetylated in cell lines where p57KIP2 was methylated at the transcription start site. Regional methylation and histone deacetylation thus appear to be crucially involved in the silencing of p57KIP2 expression in human tumors.
Kikuchi
Takefumi
T
First Department of Internal Medicine, Sapporo Medical University, Sapporo 060-8543, Japan.
Toyota
Minoru
M
Itoh
Fumio
F
Suzuki
Hiromu
H
Obata
Toshiro
T
Yamamoto
Hiroyuki
H
Kakiuchi
Hideki
H
Kusano
Masanobu
M
Issa
Jean-Pierre J
JP
Tokino
Takashi
T
Imai
Kohzoh
K
D000107:Acetylation; D002843:Chromatin / Q000378:metabolism; D018899:CpG Islands / Q000502:physiology; D050761:Cyclin-Dependent Kinase Inhibitor p57; D019175:DNA Methylation; D017931:DNA Primers / Q000737:chemistry; D004273:DNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006657:Histones / Q000378:metabolism*; D006801:Humans; D009369:Neoplasms / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012313:RNA / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
C493964:CDKN1C protein, human; D002843:Chromatin; D050761:Cyclin-Dependent Kinase Inhibitor p57; D017931:DNA Primers; D004273:DNA, Neoplasm; D006657:Histones; D009687:Nuclear Proteins; D012313:RNA