Linked Life Data

17620345

Source:http://linkedlifedata.com/resource/pubmed/id/17620345

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
2007-9-25
pubmed:abstractText
1-[4-(2-Dimethylaminoethoxy)-phenyl]-1,2-diphenylbut-1-(Z)-ene (tamoxifen, TAM) is a nonsteroidal antiestrogen that has been commonly used for the prevention and treatment of estrogen receptor-positive breast cancer. TAM is extensively metabolized into several primary active metabolites including 4-hydroxy-TAM (4-OH-TAM) and endoxifen. Glucuronidation is the major phase II metabolic pathway important in their excretion. Whereas high antiestrogenic activity has been reported for both 4-OH-TAM and endoxifen, studies examining the effect of glucuronide conjugation of these metabolites have not previously been performed. In the present study, the antiestrogenic activities of glucuronidated TAM metabolites were determined by examining their effect on the induction of the estrogen-responsive progesterone receptor (PGR) gene. 17beta-Estradiol (E(2))-mediated PGR gene expression in MCF-7 cells was determined by real-time reverse transcriptase-polymerase chain reaction for each TAM metabolite isomer. E(2) (1 x 10(-10) M) induction of PGR mRNA was 6-fold after a 12-h incubation; only unconjugated TAM metabolites inhibited this effect. A virtually identical dose-dependent inhibition of E(2)-induced PGR gene expression was found for both the trans- and cis-isomers of 4-OH-TAM and endoxifen, with maximal inhibition attained at 1 x 10(-6) M of TAM metabolite. The glucuronide conjugates of all 4-OH-TAM and endoxifen isomers exhibited no effect on E(2)-mediated induction of PGR expression at all concentrations of TAM metabolite examined in this study. These data indicate that isomers of both 4-OH-TAM and endoxifen exhibit roughly equipotent antiestrogenic effects on E(2)-induced gene expression and that glucuronide conjugates of the same metabolites effectively negate this activity. This result may have important implications in terms of both whole-body and target tissue-specific glucuronidation pathways and individual responses to TAM therapy and cancer prevention.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0090-9556
pubmed:author
pubmed:issnType
Print
pubmed:volume
35
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1942-8
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Elimination of antiestrogenic effects of active tamoxifen metabolites by glucuronidation.
pubmed:affiliation
Cancer Prevention and Control, Penn State Cancer Institute, Penn State College of Medicine, Hershey, PA, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural