title: A novel mechanism for CTCF in the epigenetic regulation of Bax in breast cancer cells.
abstract: We previously reported the association of elevated levels of the multifunctional transcription factor, CCCTC binding factor (CTCF), in breast cancer cells with the specific anti-apoptotic function of CTCF. To understand the molecular mechanisms of this phenomenon, we investigated regulation of the human Bax gene by CTCF in breast and non-breast cells. Two CTCF binding sites (CTSs) within the Bax promoter were identified. In all cells, breast and non-breast, active histone modifications were present at these CTSs, DNA harboring this region was unmethylated, and levels of Bax mRNA and protein were similar. Nevertheless, up-regulation of Bax mRNA and protein and apoptotic cell death were observed only in breast cancer cells depleted of CTCF. We proposed that increased CTCF binding to the Bax promoter in breast cancer cells, by comparison with non-breast cells, may be mechanistically linked to the specific apoptotic phenotype in CTCF-depleted breast cancer cells. In this study, we show that CTCF binding was enriched at the Bax CTSs in breast cancer cells and tumors; in contrast, binding of other transcription factors (SP1, WT1, EGR1, and c-Myc) was generally increased in non-breast cells and normal breast tissues. Our findings suggest a novel mechanism for CTCF in the epigenetic regulation of Bax in breast cancer cells, whereby elevated levels of CTCF support preferential binding of CTCF to the Bax CTSs. In this context, CTCF functions as a transcriptional repressor counteracting influences of positive regulatory factors; depletion of breast cancer cells from CTCF therefore results in the activation of Bax and apoptosis.
authors.affiliation: School of Biological Sciences, University of Essex, Colchester, Essex, United Kingdom.
authors.forename: Claudia Fabiola
authors.initials: CF
authors.lastname: Méndez-Catalá
authors.forename: Svetlana
authors.initials: S
authors.lastname: Gretton
authors.forename: Alexander
authors.initials: A
authors.lastname: Vostrov
authors.forename: Elena
authors.initials: E
authors.lastname: Pugacheva
authors.forename: Dawn
authors.initials: D
authors.lastname: Farrar
authors.forename: Yoko
authors.initials: Y
authors.lastname: Ito
authors.forename: France
authors.initials: F
authors.lastname: Docquier
authors.forename: Georgia-Xanthi
authors.initials: GX
authors.lastname: Kita
authors.forename: Adele
authors.initials: A
authors.lastname: Murrell
authors.forename: Victor
authors.initials: V
authors.lastname: Lobanenkov
authors.forename: Elena
authors.initials: E
authors.lastname: Klenova
mesh_terms: D017209:Apoptosis / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D001667:Binding, Competitive; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D000076246:CCCTC-Binding Factor; D045744:Cell Line, Tumor; D044127:Epigenesis, Genetic; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D020014:K562 Cells; D061986:MCF-7 Cells; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D034622:RNA Interference; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051028:bcl-2-Associated X Protein / Q000235:genetics* / Q000378:metabolism
chemical_list: D000076246:CCCTC-Binding Factor; C000619697:CTCF protein, human; D012097:Repressor Proteins; D051028:bcl-2-Associated X Protein
references.citation: Int J Cancer. 2012 Apr 15;130(8):1715-25
references.pmid: 22025288
references.citation: Cell. 2009 Jun 26;137(7):1194-211
references.pmid: 19563753
references.citation: Clin Cancer Res. 2009 Sep 15;15(18):5762-71
references.pmid: 19737964
references.citation: Cancer Res. 1996 May 1;56(9):2148-56
references.pmid: 8616864
references.citation: Cell Death Differ. 2008 Feb;15(2):354-63
references.pmid: 18034190
references.citation: Nucleic Acids Res. 2001 May 1;29(9):e45
references.pmid: 11328886
references.citation: Trends Genet. 2001 Sep;17(9):520-7
references.pmid: 11525835
references.citation: J Biol Chem. 2005 Jul 29;280(30):28152-61
references.pmid: 15941718
references.citation: Nucleic Acids Res. 2003 Dec 15;31(24):e154
references.pmid: 14654707
references.citation: Cell Cycle. 2006 Jun;5(12):1249-53
references.pmid: 16760668
references.citation: Int J Cancer. 2002 Jun 1;99(4):589-96
references.pmid: 11992551
references.citation: Anal Biochem. 2011 May 15;412(2):183-8
references.pmid: 21284925
references.citation: Hum Mol Genet. 2005 Apr 1;14(7):953-65
references.pmid: 15731119
references.citation: Cell Death Differ. 2012 Nov;19(11):1733-40
references.pmid: 22935609
references.citation: Int J Cancer. 2000 Aug 15;87(4):517-21
references.pmid: 10918191
references.citation: J Cell Physiol. 2012 Feb;227(2):479-92
references.pmid: 21465478
references.citation: Nucleic Acids Res. 2005 Dec 02;33(21):6850-60
references.pmid: 16326864
references.citation: J Neurosci. 2007 Mar 14;27(11):2793-801
references.pmid: 17360901
references.citation: Curr Opin Genet Dev. 2007 Oct;17(5):400-7
references.pmid: 17913488
references.citation: Oncogene. 2009 Feb 26;28(8):1121-31
references.pmid: 19137013
references.citation: Mol Cell Biol. 2010 Mar;30(5):1199-216
references.pmid: 20038529
references.citation: Oncogene. 1990 Dec;5(12):1743-53
references.pmid: 2284094
references.citation: Cell Res. 2006 Feb;16(2):203-13
references.pmid: 16474435
references.citation: Cell Commun Signal. 2010 Dec 22;8:31
references.pmid: 21176168
references.citation: Oncogene. 2008 Oct 27;27(50):6507-21
references.pmid: 18955976
references.citation: Epigenetics. 2011 Sep 1;6(9):1068-77
references.pmid: 21814038
references.citation: Nat Genet. 2011 Jun 19;43(7):630-8
references.pmid: 21685913
references.citation: Mol Cell Biol. 1996 Jun;16(6):2802-13
references.pmid: 8649389
references.citation: Methods Mol Biol. 2011;731:237-45
references.pmid: 21516412
references.citation: Cell. 2007 May 18;129(4):823-37
references.pmid: 17512414
references.citation: Biochim Biophys Acta. 2005 May 30;1740(2):206-14
references.pmid: 15949688
references.citation: Semin Cancer Biol. 2002 Oct;12(5):399-414
references.pmid: 12191639
references.citation: Genome Res. 2009 Jan;19(1):24-32
references.pmid: 19056695
references.citation: Cell. 2008 Jun 13;133(6):1106-17
references.pmid: 18555785
references.citation: Cancer Res. 2005 Jun 15;65(12):5112-22
references.pmid: 15958555
references.citation: Breast Cancer Res Treat. 1999 Dec;58(3):193-204
references.pmid: 10718481
references.citation: Cancer Treat Res. 2003;115:319-43
references.pmid: 12613203
references.citation: Br J Cancer. 2008 Feb 12;98(3):571-9
references.pmid: 18195709
references.citation: Nat Rev Cancer. 2002 Sep;2(9):647-56
references.pmid: 12209154
references.citation: Cell. 1997 Feb 7;88(3):355-65
references.pmid: 9039262
references.citation: Neurosci Lett. 2007 Aug 16;423(2):89-94
references.pmid: 17692461
references.citation: Bioessays. 2010 Jan;32(1):37-50
references.pmid: 20020479
references.citation: Proc Natl Acad Sci U S A. 1998 Apr 28;95(9):4997-5002
references.pmid: 9560217
references.citation: Cell. 2007 Mar 23;128(6):1231-45
references.pmid: 17382889
references.citation: J Cell Mol Med. 2006 Jul-Sep;10(3):554-68
references.pmid: 16989720
references.citation: Cell. 1995 Jan 27;80(2):293-9
references.pmid: 7834749
references.citation: Cancer Res. 2000 Nov 15;60(22):6318-25
references.pmid: 11103792
references.citation: J Clin Invest. 1996 Jun 1;97(11):2651-9
references.pmid: 8647960
references.citation: Bioinformatics. 2005 Nov 1;21(21):4067-8
references.pmid: 16141249
references.citation: Carcinogenesis. 2006 Oct;27(10):1939-45
references.pmid: 16606631