Reference : Ku proteins interact with activator protein-2 transcription factors and contribute to ER...
Scientific journals : Article
Human health sciences : Oncology
http://hdl.handle.net/2268/35202
Ku proteins interact with activator protein-2 transcription factors and contribute to ERBB2 overexpression in breast cancer cell lines.
English
Nolens, Grégory[Université de Liège - ULg > GIGA research > Oncologie Moléculaire > GIGA - Membres >]
Pignon, Jean-Christophe[Université de Liège - ULg > GIGA research > Oncologie Moléculaire > Doct. sc. bioméd. & pharma. (Bologne) >]
Koopmansch, Benjamin[Université de Liège - ULg > Département des sciences biomédicales et précliniques > GIGA-R : Oncologie moléculaire >]
Elmoualij, Benaïssa[Université de Liège - ULg > Département des sciences biomédicales et précliniques > Histologie humaine >]
Zorzi, Willy[Université de Liège - ULg > Département des sciences biomédicales et précliniques > Histologie humaine - Département des sciences biomédicales et précliniques >]
De Pauw, Edwin[Université de Liège - ULg > Département de chimie (sciences) > GIGA-R : Laboratoire de spectrométrie de masse (L.S.M.) >]
Winkler, Rose[Université de Liège - ULg > Département des sciences biomédicales et précliniques > Anatomie et cytologie pathologiques >]
[en] INTRODUCTION: Activator protein-2 (AP-2) alpha and AP-2 gamma transcription factors contribute to ERBB2 gene overexpression in breast cancer. In order to understand the mechanism by which the ERBB2 gene is overexpressed we searched for novel AP-2 interacting factors that contribute to its activity. METHODS: Ku proteins were identified as AP-2 alpha interacting proteins by glutathione serine transferase (GST)-pull down followed by mass spectrometry. Transfection of the cells with siRNA, expression vectors and reporter vectors as well as chromatin immunoprecipitation (ChIP) assay were used to ascertain the implication of Ku proteins on ERBB2 expression. RESULTS: Nuclear proteins from BT-474 cells overexpressing AP-2 alpha and AP-2 gamma were incubated with GST-AP2 or GST coated beads. Among the proteins retained specifically on GST-AP2 coated beads Ku70 and Ku80 proteins were identified by mass spectrometry. The contribution of Ku proteins to ERBB2 gene expression in BT-474 and SKBR3 cell lines was investigated by downregulating Ku proteins through the use of specific siRNAs. Depletion of Ku proteins led to downregulation of ERBB2 mRNA and protein levels. Furthermore, reduction of Ku80 in HCT116 cell line decreased the AP-2 alpha activity on a reporter vector containing an AP-2 binding site linked to the ERBB2 core promoter, and transfection of Ku80 increased the activity of AP-2 alpha on this promoter. Ku siRNAs also inhibited the activity of this reporter vector in BT-474 and SKBR3 cell lines and the activity of the ERBB2 promoter was further reduced by combining Ku siRNAs with AP-2 alpha and AP-2 gamma siRNAs. ChIP experiments with chromatin extracted from wild type or AP-2 alpha and AP-2 gamma or Ku70 siRNA transfected BT-474 cells demonstrated Ku70 recruitment to the ERBB2 proximal promoter in association with AP-2 alpha and AP-2 gamma. Moreover, Ku70 siRNA like AP-2 siRNAs, greatly reduced PolII recruitment to the ERBB2 proximal promoter. CONCLUSIONS: Ku proteins in interaction with AP-2 (alpha and gamma) contribute to increased ERBB2 mRNA and protein levels in breast cancer cells.
Giga-Cancer
Fonds de la Recherche Scientifique (Communauté française de Belgique) - F.R.S.-FNRS
[Université de Liège - ULg > GIGA research > Oncologie Moléculaire > GIGA - Membres >]
