title: Oct4 is epigenetically regulated by methylation in normal placenta and gestational trophoblastic disease.
abstract: Oct4 is a transcription factor that plays a crucial role in maintaining pluripotency of embryonic stem cells. Down-regulation of Oct4 is associated with the differentiation of trophectoderm cell lineage, from which the normal placenta derives. We investigated the methylation and expression status of Oct4 in normal placenta and gestational trophoblastic disease (GTD) as attempts to investigate the role of Oct4 in the pathogenesis of GTD. By methylation-specific PCR, we observed both methylated and unmethylated Oct4 alleles in all 25 first trimester and 10 term placentas while 33% (18/54) of hydatidiform moles, and two choriocarcinoma cell line (JEG3 and JAR), only displayed methylated Oct4 allele. By quantitative TaqMan real-time PCR, Oct4 mRNA was significantly reduced in hydatidiform moles (P=0.04), JEG3 and JAR (P=0.024) when compared with normal placentas. Oct4 methylation was significantly correlated with Oct4 mRNA expression in placenta and GTD (P=0.012). Hypermethylation in minimal promoter and exon 1 region of Oct4 were confirmed in JEG3 and JAR by bisulfite genomic sequencing. The Oct4 mRNA expression in JEG3 and JAR increased after treatment with 5-aza-2'-deoxycytidine and/or trichostatin A. Our findings suggest that Oct4 is down-regulated by hypermethylation in normal placenta and GTD and such process is important in pathogenesis of GTD.
authors.affiliation: Department of Pathology, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Hong Kong Special Administrative Region, China.
authors.forename: H-J
authors.initials: HJ
authors.lastname: Zhang
authors.forename: M K-Y
authors.initials: MK
authors.lastname: Siu
authors.forename: E S-Y
authors.initials: ES
authors.lastname: Wong
authors.forename: K-Y
authors.initials: KY
authors.lastname: Wong
authors.forename: A S-M
authors.initials: AS
authors.lastname: Li
authors.forename: K Y-K
authors.initials: KY
authors.lastname: Chan
authors.forename: H Y-S
authors.initials: HY
authors.lastname: Ngan
authors.forename: A N-Y
authors.initials: AN
authors.lastname: Cheung
mesh_terms: D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D045744:Cell Line, Tumor; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors; D000077209:Decitabine; D004791:Enzyme Inhibitors / Q000494:pharmacology; D044127:Epigenesis, Genetic / Q000502:physiology; D005091:Exons; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D031901:Gestational Trophoblastic Disease / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D050814:Octamer Transcription Factor-3 / Q000235:genetics* / Q000378:metabolism; D010920:Placenta / Q000378:metabolism* / Q000473:pathology; D011247:Pregnancy; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D006877:Hydroxamic Acids; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; D012333:RNA, Messenger; C012589:trichostatin A; D000077209:Decitabine; D015254:DNA Modification Methylases; D001374:Azacitidine