ORBi: Delacroix Laurence - Distal ERBB2 promoter fragment displays specific transcriptional and nuclear binding activities in ERBB2 overexpressing breast cancer cells

Reference : Distal ERBB2 promoter fragment displays specific transcriptional and nuclear binding act...


	Document type :	Scientific journals : Article
	Discipline(s) :	Human health sciences : Oncology Life sciences : Genetics & genetic processes Life sciences : Biochemistry, biophysics & molecular biology
	To cite this reference:	http://hdl.handle.net/2268/4235

Title :	Distal ERBB2 promoter fragment displays specific transcriptional and nuclear binding activities in ERBB2 overexpressing breast cancer cells
Language :	English
Alternative title :	[fr] Un fragment distal du promoteur ERBB2 présente des activités transcriptionnelles et de liaison nucléaire spécifiques dans les cellules de cancer du sein surexprimant ERBB2
Author, co-author :	Delacroix, Laurence [Université de Liège - ULg > Département des sciences cliniques > GIGA-R:Immunopath. - Maladies infect. et médec. inter. gén. >]
	Begon, Dominique [Université de Liège - ULg > Département des sciences biomédicales et précliniques > Anatomie et cytologie pathologiques - Laboratoire d'Oncologie Moléculaire > >]
	Chatel, Guillaume [Université de Liège - ULg > Département des sciences biomédicales et précliniques > Anatomie et cytologie pathologiques - Laboratoire d'Oncologie Moléculaire > >]
	Jackers, Pascale [Université de Liège - ULg > Département des sciences biomédicales et précliniques > Anatomie et cytologie pathologiques - Laboratoire d'Oncologie Moléculaire > > >]
	Winkler, Rose [Université de Liège - ULg > Département des sciences biomédicales et précliniques > Anatomie et cytologie pathologiques - Laboratoire d'Oncologie Moléculaire > >]
Publication date :	Sep-2005
Journal title :	DNA & Cell Biology
Publisher :	Mary Ann Liebert, Inc.
Volume :	24
Issue/season :	9
Pages :	582-594
Audience :	International
ISSN :	1044-5498
e-ISSN :	1557-7430
City :	Larchmont
Country :	NY
Keywords :	[en] ERBB2 oncogene ; promoter ; transcription ; breast cancer ; BT-474 ; MDA-MB-231 ; AP-2 transcription factor ; transfection ; luciferase ; EMSA ; chromatin immunoprecipitation, ChIP ; DNA binding
Abstract :	[en] Overexpression of the ERBB2 gene occurs in 30% of human breast cancers and is correlated with poor prognosis. The deregulation is the consequence of an increased transcription level and gene amplification. Several laboratories, including our own, have identified, in the proximal promoter, enhancers implicated in the gene overexpression. However, our previous studies of a 6-kb ERBB2 promoter fragment revealed the presence of repressing fragments, which were able to overcome the effect of the proximal enhancers. These repressing elements were functional in all cell lines, regardless of their endogenous ERBB2 expression level. Here, we show that a distal ERBB2 promoter region restores high transcription rates specifically in ERBB2 overexpressing breast cancer cells. This distal promoter region thus contains enhancers essential for the overexpression of the gene. By EMSA, performed with nuclear extract of cells overexpressing (BT-474) or not (MDA-MB-231) the ERBB2 gene, we show that at least two sequences of the distal promoter region are bound exclusively by BT-474 extract. Further experiments reveal that AP-2 transcription factors contribute to this differential binding activity, by binding recognition sequences located 4500 bp and 4000 bp upstream of the transcription start site. These sites are occupied by AP2 in vivo, as demonstrated by ChIP assay. Inactivation of AP-2 proteins in ERBB2 overexpressing cells reduces the distal promoter activity up to 70%, indicating the AP-2 factors are implicated in the strong distal enhancing effect. Moreover, we identified a 54-bp fragment that is bound specifically by BT-474 nuclear extract. Further experiments did not lead to the identification of the protein responsible for this binding. Our results thus highlight the importance of ERBB2 distal promoter region and further implicate AP-2 in ERBB2 overexpression in breast cancer cells.
Research units :	Giga-Cancer
Funders :	Fonds de la Recherche Scientifique (Communauté française de Belgique) - F.R.S.-FNRS ; Fonds Léon Fredericq (Liège, Belgique) ; Centre Anticancéreux attaché à l'Université de Liège ; Fédération Belge contre le Cancer ; Télévie (Belgique)
Target :	Researchers ; Professionals ; Students
Permalink :	http://hdl.handle.net/2268/4235
	also: http://hdl.handle.net/2268/24826
DOI :	10.1089/dna.2005.24.582
Other URL :	http://www.liebertonline.com/doi/abs/10.1089/dna.2005.24.582

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