Linked Life Data

10348797

Source:http://linkedlifedata.com/resource/pubmed/id/10348797

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1999-7-16
pubmed:abstractText
Earlier study suggested that 3,4-dihydroxytamoxifen (tam catechol), a tamoxifen metabolite, is proximate to the reactive intermediate that binds covalently to proteins and possibly to DNA (). The current study demonstrates that rat and human hepatic cytochrome P-450s (CYPs) catalyze tam catechol formation from tamoxifen (tam), 3-hydroxy-tam (Droloxifene), and 4-hydroxy-tam (4-OH-tam). Higher levels of catechol were formed from 4-OH-tam and 3-hydroxy-tam than from tam. Evidence that human hepatic CYP3A4 and 2D6 catalyze the formation of tam catechol from 4-OH-tam and supportive data that the catechol is proximate to the reactive intermediate, was obtained: 1) There was a good correlation (r = 0.82; p </=.0004) between steroidal 6beta-hydroxylase (CYP3A activity) and ortho hydroxylation of 4-OH-tam in human liver microsomes; 2) monospecific antibodies against CYP3A4 strongly inhibited catechol formation from 4-OH-tam and its covalent binding to proteins in human liver microsomes; 3) low levels of ketoconazole inhibited catechol tam accumulation and covalent binding of 4-OH-tam to human liver proteins; 4) among human P-450s expressed in insect cells (supersomes), only CYP3A4 and 2D6 noticeably catalyzed catechol formation, and cytochrome b5 markedly stimulated the CYP3A4 catalysis; and 5) human livers with high CYP3A and low or high CYP2D6 activity exhibited high catechol formation and those with low 3A and 2D6 activities formed only little catechol. These findings demonstrate that CYP3A4 and to a lesser extent 2D6 catalyze tam catechol formation and support the participation of tam catechol in covalent binding to proteins.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/3-hydroxytamoxifen, http://linkedlifedata.com/resource/pubmed/chemical/4-hydroxytamoxifen, http://linkedlifedata.com/resource/pubmed/chemical/CYP3A protein, human, http://linkedlifedata.com/resource/pubmed/chemical/CYP3A4 protein, human, http://linkedlifedata.com/resource/pubmed/chemical/Catechols, http://linkedlifedata.com/resource/pubmed/chemical/Cytochrome P-450 CYP2D6, http://linkedlifedata.com/resource/pubmed/chemical/Cytochrome P-450 CYP3A, http://linkedlifedata.com/resource/pubmed/chemical/Cytochrome P-450 Enzyme System, http://linkedlifedata.com/resource/pubmed/chemical/Estrogen Antagonists, http://linkedlifedata.com/resource/pubmed/chemical/Mixed Function Oxygenases, http://linkedlifedata.com/resource/pubmed/chemical/Pentobarbital, http://linkedlifedata.com/resource/pubmed/chemical/Tamoxifen
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0090-9556
pubmed:author
pubmed:issnType
Print
pubmed:volume
27
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
681-8
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Cytochrome P-450 3A and 2D6 catalyze ortho hydroxylation of 4-hydroxytamoxifen and 3-hydroxytamoxifen (droloxifene) yielding tamoxifen catechol: involvement of catechols in covalent binding to hepatic proteins.
pubmed:affiliation
Worcester Foundation for Biomedical Research and Department of Pharmacology and Molecular Toxicology, University of Massachusetts Medical Center, Worcester, Massachusetts 01655, USA.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S.