Involvement of HP1alpha protein in irreversible transcriptional inactivation by antiestrogens in breast cancer cells

Joan Oliva; Selma El Messaoudi; Franck Pellestor; Maryse Fuentes; Virginie Georget; Patrick Balaguer; Vincent Cavaillès; Françoise Vignon; Eric Badia

doi:10.1016/j.febslet.2005.06.060

Involvement of HP1alpha protein in irreversible transcriptional inactivation by antiestrogens in breast cancer cells

FEBS Lett. 2005 Aug 15;579(20):4278-86. doi: 10.1016/j.febslet.2005.06.060.

Authors

Joan Oliva¹, Selma El Messaoudi, Franck Pellestor, Maryse Fuentes, Virginie Georget, Patrick Balaguer, Vincent Cavaillès, Françoise Vignon, Eric Badia

Affiliation

¹ Institut National de la Santé et de la Recherche Médicale U540, Endocrinologie Moléculaire et Cellulaire des Cancers and Université de Montpellier I, 60 rue de Navacelles, 34090 Montpellier, France.

PMID: 16051232
DOI: 10.1016/j.febslet.2005.06.060

Abstract

Resistance to 4-hydroxy-tamoxifen (OHT), which appears in breast cancer cells after long-term antiestrogen treatment, may involve irreversible changes of gene expression. We previously developed a MCF-7 derived cell line (MVLN), in which OHT rapidly and irreversibly inactivates the expression of an estrogen-regulated luciferase transgene (Vit-tk-luciferase). In chromatin immunoprecipitation experiments, heterochromatin protein 1 (HP1alpha) was found to be associated with the Vit-tk-luciferase transgene, only when it was inactivated by OHT treatment. Chimeras composed of either HP1alpha or the Krupple-associated box (KRAB) module of KOX-1 protein (known to repress gene expression by recruitment of HP1 proteins), fused to the estrogen receptor (ER)-DNA binding domain (DBD) and the androgen receptor (AR)-ligand binding domain (LBD) were generated and appeared as potent transcriptional repressors. In stably transfected MVLN cells, irreversible inactivation of the luciferase transgene expression obtained with HP1alpha-ER(DBD)-AR(LBD) was partial, whereas inactivation obtained with KRAB-ER(DBD)-AR(LBD) was comparable to that obtained with OHT, although with a slower kinetics. Altogether, these data suggest that HP1alpha is involved in the silencing effects associated with long-term OHT treatments.

MeSH terms

Breast Neoplasms / genetics*
Breast Neoplasms / immunology
Breast Neoplasms / metabolism
Chromatin Immunoprecipitation
Chromobox Protein Homolog 5
Chromosomal Proteins, Non-Histone / metabolism*
DNA-Binding Proteins / analysis
DNA-Binding Proteins / genetics
DNA-Binding Proteins / metabolism
Drug Resistance, Neoplasm / genetics
Estrogen Antagonists / pharmacology*
Gene Silencing*
Humans
Kruppel-Like Transcription Factors
Luciferases / analysis
Luciferases / genetics
Protein Isoforms / metabolism
Receptors, Androgen / analysis
Receptors, Androgen / genetics
Receptors, Androgen / metabolism
Receptors, Estrogen / analysis
Receptors, Estrogen / genetics
Receptors, Estrogen / metabolism
Recombinant Fusion Proteins / analysis
Recombinant Fusion Proteins / genetics
Recombinant Fusion Proteins / metabolism
Repressor Proteins / analysis
Repressor Proteins / genetics
Repressor Proteins / metabolism
Tamoxifen / analogs & derivatives*
Tamoxifen / pharmacology
Transcription, Genetic / drug effects*
Transgenes
Tumor Cells, Cultured

Substances

CBX5 protein, human
Chromosomal Proteins, Non-Histone
DNA-Binding Proteins
Estrogen Antagonists
Kruppel-Like Transcription Factors
Protein Isoforms
Receptors, Androgen
Receptors, Estrogen
Recombinant Fusion Proteins
Repressor Proteins
ZNF10 protein, human
Tamoxifen
Chromobox Protein Homolog 5
afimoxifene
Luciferases