title: Oct-4B isoform is differentially expressed in breast cancer cells: hypermethylation of regulatory elements of Oct-4A suggests an alternative promoter and transcriptional start site for Oct-4B transcription.
abstract: The human Oct-4 gene has three isoforms, Oct-4A, Oct-4B and Oct-4B1, which are thought to be derived from alternative splicing. It remains controversial whether the Oct-4 gene is expressed in cancer cells. Expression of Oct-4A is regulated by two elements, the PE (proximal enhancer) and DE (distal enhancer), but the expression and regulation of Oct-4B are not well known. Here, we firstly report that Oct-4B is expressed at low levels in MCF-7 cells, while the Oct-4A gene is inactivated. By analysing the function of different promoter constructs and the DNA methylation status of three regulatory regions, we demonstrate that the Oct-4A gene in MCF-7 cells is repressed by epigenetic control rather than transcriptional control. In addition, we speculate that the transcription of Oct-4B in MCF-7 cells is differentially regulated by additional regulatory elements. This work will enhance the understanding of Oct-4 gene in differential regulation.
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing 100193, People's Republic of China.
authors.forename: Yajuan
authors.initials: Y
authors.lastname: Wang
authors.forename: Lu
authors.initials: L
authors.lastname: Meng
authors.forename: Hongyu
authors.initials: H
authors.lastname: Hu
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Chenfu
authors.initials: C
authors.lastname: Zhao
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Li
authors.forename: Fangyu
authors.initials: F
authors.lastname: Shi
authors.forename: Xudong
authors.initials: X
authors.lastname: Wang
authors.forename: Aixing
authors.initials: A
authors.lastname: Lin
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D019175:DNA Methylation / Q000235:genetics; D044127:Epigenesis, Genetic; D005260:Female; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006801:Humans; D050814:Octamer Transcription Factor-3 / Q000235:genetics* / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D050436:Regulatory Elements, Transcriptional; D012045:Regulatory Sequences, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D024363:Transcription Initiation Site
chemical_list: D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; D020033:Protein Isoforms; D014157:Transcription Factors