Linked Life Data

7517003

Source:http://linkedlifedata.com/resource/pubmed/id/7517003

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1994-7-28
pubmed:abstractText
We find that stimulation of the protein kinase A (PKA) signaling pathway in MCF-7 human breast cancer cells changes the agonist/antagonist activity of tamoxifen and related antiestrogens; it activates or enhances their estrogen agonist activity and reduces their ability to antagonize the effects of estradiol (E2). In MCF-7 human breast cancer cells which contain high levels of endogenous estrogen receptor (ER), the antiestrogen trans-hydroxy-tamoxifen (TOT) fails to stimulate transcription of the estrogen-responsive promoter-reporter constructs estrogen response element (ERE)-TATA-chloramphenicol acetyl transferase (CAT), (ERE)2-TATA-CAT, and pS2-CAT. However, when cells are treated with isobutyl methylxanthine plus cholera toxin (which increases intracellular cAMP approximately 10-fold), or with 8-bromo-cAMP, or are transfected with expression vectors for the PKA catalytic subunits, the transcriptional activity of the antiestrogen-ER complex is now increased, to levels 20-75% that of E2, and TOT also becomes much less effective in antagonizing the stimulation of transcription by E2. Although this alteration in the agonist and antagonist activity of TOT is observed with three promoter-reporter constructs, containing a simple TATA promoter or a more complex, pS2 promoter, elevation of cAMP did not enhance the transcription by either TOT or E2 of the reporter plasmid ERE-thymidine kinase-CAT. Thus, this phenomenon is promoter specific. The maximal stimulatory effects of isobutylmethylxanthine plus cholera toxin and PKA catalytic subunits on TOT and E2 transcriptional enhancement were not additive, consistent with the hypothesis that they are both acting via stimulation of the same signal transduction pathway.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0888-8809
pubmed:author
pubmed:issnType
Print
pubmed:volume
8
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
296-304
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed-meshheading:7517003-1-Methyl-3-isobutylxanthine, pubmed-meshheading:7517003-Breast Neoplasms, pubmed-meshheading:7517003-Cholera Toxin, pubmed-meshheading:7517003-Cyclic AMP, pubmed-meshheading:7517003-Cyclic AMP-Dependent Protein Kinases, pubmed-meshheading:7517003-Enzyme Activation, pubmed-meshheading:7517003-Estradiol, pubmed-meshheading:7517003-Estrogen Antagonists, pubmed-meshheading:7517003-Humans, pubmed-meshheading:7517003-Immunoblotting, pubmed-meshheading:7517003-Polyunsaturated Alkamides, pubmed-meshheading:7517003-Promoter Regions, Genetic, pubmed-meshheading:7517003-Receptors, Estrogen, pubmed-meshheading:7517003-Signal Transduction, pubmed-meshheading:7517003-Transcription, Genetic, pubmed-meshheading:7517003-Transfection, pubmed-meshheading:7517003-Tumor Cells, Cultured
pubmed:year
1994
pubmed:articleTitle
Alteration in the agonist/antagonist balance of antiestrogens by activation of protein kinase A signaling pathways in breast cancer cells: antiestrogen selectivity and promoter dependence.
pubmed:affiliation
Department of Physiology and Biophysics, University of Illinois, Urbana 61801.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.