title: Nanog expression is negatively regulated by protein kinase C activities in human cancer cell lines.
abstract: Nanog is a transcription factor that is essential for the maintenance of pluripotency of the embryonic stem cells. Nanog has been shown to be expressed in various kinds of human tumors, suggesting a role in tumorigenesis. In this study, we found that Nanog expression was upregulated by inhibition of protein kinase C (PKC) activity in six human cancer cell lines examined. In a Nanog non-expressing human nasopharyngeal carcinoma cell line, NPC-076, Nanog mRNA level and protein level were both induced and dose-dependently promoted by exposure to PKC inhibitors. Knockdown experiments showed that PKCα and PKCδ were two subtypes exerted most of the effect. The reporter assay showed that Nanog promoter activity was promoted by exposure of the cells to PKC inhibitors and the effect was dependent on the presence of the Octamer-Sox composite element. The involvement of Octamer-Sox composite element was further supported by the observation that silencing of Oct4 and Sox2 in NPC-076 cells attenuated the effects of PKC inhibitors. In Nanog-expressing human embryonal carcinoma cell lines, NT2/D1 and NCCIT, Nanog expression was suppressed by exposure to PKC activator Phorbol-12-myristate-13-acetate (PMA). Further study showed that overexpression of PKCα elicited a repressive effect on Nanog expression in NT2/D1 cells. Consistently, mutation of the Octamer-Sox composite element abolished the suppressive effect by PKC activator. Nanog expression was of cellular significance in that ectopic expression in NPC-076 stimulated cell proliferation and knockdown of the endogenous Nanog expression in NT2/D1-suppressed cell proliferation.
authors.affiliation: Department of Physiology, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan.
authors.forename: Wing-Keung
authors.initials: WK
authors.lastname: Chu
authors.forename: Pei-Min
authors.initials: PM
authors.lastname: Dai
authors.forename: Hsin-Lun
authors.initials: HL
authors.lastname: Li
authors.forename: Chia-Chu
authors.initials: CC
authors.lastname: Pao
authors.forename: Jan-Kan
authors.initials: JK
authors.lastname: Chen
mesh_terms: D002277:Carcinoma; D049109:Cell Proliferation; D018450:Disease Progression; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D056945:Hep G2 Cells; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D000071317:Nanog Homeobox Protein; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000201:enzymology / Q000473:pathology; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D051571:Protein Kinase C-alpha / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051745:Protein Kinase C-delta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D055748:SOXB1 Transcription Factors / Q000235:genetics / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives / Q000494:pharmacology; D014158:Transcription, Genetic
chemical_list: D004791:Enzyme Inhibitors; D018398:Homeodomain Proteins; D007527:Isoenzymes; C486780:NANOG protein, human; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; D012333:RNA, Messenger; C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors; C016658:phorbolol myristate acetate; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D013755:Tetradecanoylphorbol Acetate