Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
18
pubmed:dateCreated
1988-10-11
pubmed:abstractText
Long-term tamoxifen (TAM) therapy was examined in athymic mice bearing MCF-7 tumors of different sizes. Six months of TAM treatment caused no increase in tumor size (compared to placebo treatment) for animals treated initially following implantation of tumor pieces (approximately 1 mm3) or for animals with 0.2-cm2 tumors (grown with 1 month of estrogen treatment). Tumors could be regrown with estradiol treatment in animals treated with either therapy and these tumors contained both estrogen and progesterone receptors. However, more tumors could be restimulated with estradiol following pretreatment with TAM than with placebo. A third group of animals had larger tumors (grown with 7 weeks of estrogen treatment to a approximately 0.6-cm2 area) before TAM or placebo treatment. These tumors partially regressed after 4 months of TAM or placebo therapy but began to regrow in both groups until the end of the experiment at 8 months. Tumors that grew in both groups were estrogen receptor positive and when retransplanted into athymic animals could grow with estradiol. However, the tumor that grew during TAM therapy, when retransplanted, could grow successfully only with further TAM treatment. Tumors growing with TAM contained double the estrogen receptor content of the estradiol-stimulated MCF-7 tumors that were not exposed to TAM [390 +/- 37 (SE) fmol/mg protein versus 174 +/- 14 fmol/mg protein]. These results may represent a form of TAM resistance, i.e., TAM dependence that may occur before hormone independence is exhibited.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0008-5472
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
48
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5183-7
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1988
pubmed:articleTitle
Development of tamoxifen-stimulated growth of MCF-7 tumors in athymic mice after long-term antiestrogen administration.
pubmed:affiliation
Department of Human Oncology, University of Wisconsin Clinical Cancer Center, Madison 53792.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.