Linked Life Data

8620446

Source:http://linkedlifedata.com/resource/pubmed/id/8620446

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1-2
pubmed:dateCreated
1996-6-14
pubmed:abstractText
The effect of tamoxifen (TAM) was evaluated on a mammary tumor model induced in Sprague-Dawley rats by intraperitoneal administration of three N-nitroso-N-methylurea (NMU) doses. Animals received TAM (1 mg/kg per day) from 10 days before the first NMU dose up to 140 days later. Thereafter, treatment was discontinued and the observation period was extended 60 days longer. Mean overall latency period, tumor number per rat and tumor incidence were recorded. Significant differences between treated and control batches were observed in tumor number per rat (1.8 +/- 1.1 versus 5.2 +/- 1.6; P < 0.05) and in tumor incidence (50% versus 100%; P < 0.05), respectively. No significant difference in latency period between both batches was recorded. All lesions induced in the control batch were malignant, whereas only 45% of those induced in TAM-treated animals were malignant and the remaining 55% were preneoplastic. At 60 days after treatment discontinuance, tumor incidence increased to 90% and also tumor number per rat increased to 4.6 +/- 1.5. TAM effect was also evaluated in rats with NMU-induced tumors by treatment with 1 mg/kg per day during 60 days starting when tumors reached a 1.5-cm diameter. Regression to less than 80% of initial size in 49% of the tumors was observed, while in ovariectomized rats, 33% of tumors regressed. Estrogen receptor content, ER (fmol/mg protein) and Kd (nM) in control tumors were: 56 +/- 10 and 0.5 +/- 0.1. In tumors of TAM-treated animals, ER was less than 5 fmol/mg protein. Findings demonstrate that TAM significantly decreased the appearance of tumors induced in rats by i.p. injection of NMU and when TAM treatment was initiated after tumor induction, some tumors failed to respond to hormonal manipulation. Differential tumor growth response after TAM or oophorectomy in each tumor indicates that in the same rat it is possible to distinguish hormone-dependent and hormone-autonomous tumor populations. Hormonal regulation of tumor growth can be under intrinsic control, regardless of the hormonal status of the whole organism.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0304-3835
pubmed:author
pubmed:issnType
Print
pubmed:day
27
pubmed:volume
100
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
227-34
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Effect of tamoxifen on intraperitoneal N-nitroso-N-methylurea induced tumors.
pubmed:affiliation
Laboratorio de Radioisótopos, Cátedra de Física, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't