Linked Life Data

18708366

Source:http://linkedlifedata.com/resource/pubmed/id/18708366

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
2008-8-18
pubmed:abstractText
The antiestrogen tamoxifen has been used in the treatment of hormone-responsive breast cancer for over a decade. The loss of estrogen receptor (ER) expression is the most common mechanism for de novo antiestrogen resistance. Wilms' tumor 1 suppressor gene (WT1) is a clinically useful marker that is associated with poor prognosis in breast cancer patients; its high level expression is frequently observed in cases of breast cancer that are estrogen and progesterone receptor negative. The lack of expression of these receptors is characteristic of tumor cells that are not responsive to hormonal manipulation. To determine whether there is a linkage between WT1 expression and antiestrogen resistance in breast cancer cells, we studied the effect of WT1 on tamoxifen responsiveness in ERalpha-positive MCF-7 cells. We found that overexpression of WT1 in MCF-7 markedly abrogated tamoxifen-induced cell apoptosis and 17beta-estradiol (E(2))-mediated cell proliferation. The expressions of ERalpha and its downstream target genes were significantly repressed following overexpression of WT1, whereas the down-regulation of WT1 by WT1 shRNA could enhance ERalpha expression and the sensitivity to tamoxifen treatment in ERalpha-negative MDA468 and HCC1954 cells that express high levels of WT1. Furthermore, we have confirmed that the WT1 protein can bind to endogenous WT1 consensus sites in the proximal promoter of ERalpha and thus inhibit the transcriptional activity of the ERalpha promoter in a WT1 site sequence-specific manner. Our study clearly implicates WT1 as a mediator of antiestrogen resistance in breast cancer through down-regulation of ERalpha expression and supports the development of WT1 inhibitors as a potential means of restoring antiestrogen responsiveness in breast cancer therapy.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
1541-7786
pubmed:author
pubmed:issnType
Print
pubmed:volume
6
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1347-55
pubmed:dateRevised
2011-4-21
pubmed:meshHeading
pubmed-meshheading:18708366-Animals, pubmed-meshheading:18708366-Apoptosis, pubmed-meshheading:18708366-Binding Sites, pubmed-meshheading:18708366-Breast Neoplasms, pubmed-meshheading:18708366-Cell Line, Tumor, pubmed-meshheading:18708366-Cell Proliferation, pubmed-meshheading:18708366-Consensus Sequence, pubmed-meshheading:18708366-Down-Regulation, pubmed-meshheading:18708366-Drug Resistance, Neoplasm, pubmed-meshheading:18708366-Estradiol, pubmed-meshheading:18708366-Estrogen Receptor Modulators, pubmed-meshheading:18708366-Estrogen Receptor alpha, pubmed-meshheading:18708366-Gene Expression Regulation, Neoplastic, pubmed-meshheading:18708366-Gene Silencing, pubmed-meshheading:18708366-Genes, Neoplasm, pubmed-meshheading:18708366-Mice, pubmed-meshheading:18708366-Promoter Regions, Genetic, pubmed-meshheading:18708366-RNA, Small Interfering, pubmed-meshheading:18708366-Tamoxifen, pubmed-meshheading:18708366-Transcription, Genetic, pubmed-meshheading:18708366-Transfection, pubmed-meshheading:18708366-WT1 Proteins
pubmed:year
2008
pubmed:articleTitle
Wilms' tumor 1 suppressor gene mediates antiestrogen resistance via down-regulation of estrogen receptor-alpha expression in breast cancer cells.
pubmed:affiliation
Princess Margaret Hospital/Ontario Cancer Institute, University Health Network, Toronto, Ontario, Canada M5G 2M9.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't