title: AP-2 regulates the transcription of estrogen receptor (ER)-beta by acting through a methylation hotspot of the 0N promoter in prostate cancer cells.
abstract: We reported previously that the loss of expression of estrogen receptor (ER)-beta during the development of prostate cancer (PCa) is associated with methylation of a CpG island located in the 5'-flanking sequence of the 0N promoter. Three methylation hotspots, referred to as centers 1, 2 and 3, were identified in the CpG island. In this study, we demonstrated that a 581-bp region with these three centers within it is sufficient for the promoter activity in PCa cells. Deletion analyses indicated that center 1 (16 bp), with a putative activator protein-2 (AP-2) binding site, is essential for gene transactivation. Chromatin immunoprecipitation assays showed that AP-2alpha occupies a short sequence containing center 1. Forced expression of AP-2alpha or -2gamma, but not -2beta, increased activity of the ERbeta 0N promoter and the accumulation of mRNA. Conversely, siRNA-mediated AP-2alpha and -2gamma knockdown reduced levels of ERbeta transcript and promoter activity. Quantitative reverse transcription-PCR showed that AP-2alpha and -2gamma are the predominant transcripts expressed in PCa cells, and levels of ERbeta transcript correlate with levels of these AP-2 transcripts among different PCa cell lines. These results provide the first evidence that ERbeta is an AP-2-regulated gene. They also support the hypothesis that certain cis-acting elements are methylation hotspots susceptible to epigenetic modifications during cancer progression.
authors.affiliation: Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0056, USA.
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: Y-K
authors.initials: YK
authors.lastname: Leung
authors.forename: S-M
authors.initials: SM
authors.lastname: Ho
mesh_terms: D047369:Chromatin Immunoprecipitation; D018899:CpG Islands; D019175:DNA Methylation; D047629:Estrogen Receptor beta / Q000235:genetics* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017384:Sequence Deletion; D050656:Transcription Factor AP-2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
chemical_list: D047629:Estrogen Receptor beta; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D050656:Transcription Factor AP-2