title: Regulation of DNA methyltransferase 1 by the pRb/E2F1 pathway.
abstract: Tumor suppressor gene silencing by DNA hypermethylation contributes to tumorigenesis in many tumor types. This aberrant methylation may be due to increased expression and activity of DNA methyltransferases, which catalyze the transfer of methyl groups from S-adenosylmethionine to cytosines in CpG dinucleotides. Elevated expression of the maintenance DNA methyltransferase, DNA methyltransferase 1 (DNMT-1), has been shown in carcinomas of the colon, lung, liver, and prostate. Based on the nearly ubiquitous alterations of both DNA methylation and the retinoblastoma protein (pRb) pathway found in human cancer, we investigated a potential regulatory pathway linking the two alterations in murine and human prostate epithelial cells. Analysis of DNA methyltransferase levels in Rb-/- murine prostate epithelial cell lines revealed elevated Dnmt-1 levels. Genomic DNA sequence analysis identified conserved E2F consensus binding sites in proximity to the transcription initiation points of murine and human Dnmt-1. Furthermore, the Dnmt-1 promoter was shown to be regulated by the pRb/E2F pathway in murine and human cell lines of epithelial and fibroblast origin. In the absence of pRb, Dnmt-1 transcripts exhibited aberrant cell cycle regulation and Rb-/- cells showed aberrant methylation of the paternally expressed gene 3 (Peg3) tumor suppressor gene. These findings show a link between inactivation of the pRb pathway and induction of DNA hypermethylation of CpG island-containing genes in tumorigenesis.
authors.affiliation: Department of Urology, Michigan Urology Center, University of Michigan, Ann Arbor, Michigan 48109-0944, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: McCabe
authors.forename: Joanne N
authors.initials: JN
authors.lastname: Davis
authors.forename: Mark L
authors.initials: ML
authors.lastname: Day
mesh_terms: D000818:Animals; D001665:Binding Sites; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002460:Cell Line; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D004847:Epithelial Cells / Q000201:enzymology / Q000378:metabolism / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D020868:Gene Silencing; D006801:Humans; D008297:Male; D051379:Mice; D041681:NIH 3T3 Cells; D011401:Promoter Regions, Genetic; D011467:Prostate / Q000166:cytology / Q000201:enzymology / Q000378:metabolism / Q000502:physiology; D011471:Prostatic Neoplasms / Q000201:enzymology / Q000235:genetics; D016160:Retinoblastoma Protein / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; C493754:E2f1 protein, mouse; D016160:Retinoblastoma Protein; D014157:Transcription Factors; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases