Unliganded and liganded estrogen receptors protect against cancer invasion via different mechanisms

While estrogens are mitogenic in breast cancer cells, the presence of estrogen receptor a (ERalpha) clinically indicates a favorable prognosis in breast carcinoma. To improve our understanding of ERalpha action in breast cancer, we used an original in vitro method, which combines transient transfection and Matrigel invasion assays to examine its effects on cell invasiveness. ERalpha expression in MDA-MB-231 breast cancer cells reduced their invasiveness by 3-fold in the absence of hormone and by 7-fold in its presence. Integrity of hormone and DNA-binding domains and activating function 2 were required for estradiol-induced inhibition, suggesting that transcriptional activation of estrogen target genes was involved. In contrast, these domains were dispensable for hormone-independent inhibition. Analysis of deletion mutants of ERalpha indicated that amino acids 179-215, containing the N-terminal zinc finger of the DNA-binding domain, were required for ligand-independent receptor action. Among different members of the nuclear receptor family, only unliganded ERalpha and ERbeta reduced invasion. Calreticulin, a Ca2+-binding protein that could interact with amino acids 206-211 of ERalpha, reversed hormone-independent ERalpha inhibition of invasion. However, since calreticulin alone also inhibited invasion, we propose that this protein probably prevents ERalpha interaction with another unidentified invasion-regulating factor. The inhibitor role of the unliganded ER was also suggested in three ERalpha-positive cell lines, where ERalpha content was inversely correlated with cell migration. We conclude that ERalpha protects against cancer invasion in its unliganded form, probably by protein-protein interactions with the N-terminal zinc finger region, and after hormone binding by activation of specific gene transcription.

Medienart:

Artikel

Erscheinungsjahr:

2000

Erschienen:

2000

Enthalten in:

Zur Gesamtaufnahme - volume:14

Enthalten in:

Molecular endocrinology (Baltimore, Md.) - 14(2000), 7 vom: 31. Juli, Seite 999-1009

Sprache:

Englisch

Beteiligte Personen:

Platet, N [VerfasserIn]
Cunat, S [VerfasserIn]
Chalbos, D [VerfasserIn]
Rochefort, H [VerfasserIn]
Garcia, M [VerfasserIn]

Themen:

4TI98Z838E
84LT43726C
Calcium-Binding Proteins
Calreticulin
Estradiol
Estrogen Receptor Modulators
Estrogen Receptor alpha
Estrogen Receptor beta
ICI 164384
Journal Article
Ligands
Polyunsaturated Alkamides
Receptors, Estrogen
Research Support, Non-U.S. Gov't
Ribonucleoproteins

Anmerkungen:

Date Completed 24.11.2000

Date Revised 24.11.2016

published: Print

Citation Status MEDLINE

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM108183394