PMC:13902 / 29154-30851
Annnotations
{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/13902","sourcedb":"PMC","sourceid":"13902","source_url":"http://www.ncbi.nlm.nih.gov/pmc/13902","text":"Comparison with earlier studies\nMost of the previous studies on the regulation of TGF-βs by tamoxifen and retinoids [12,13,14,17] have been done in tissue culture. Thus, the lack of effect on TGF-β expression in the present in vivo study might reflect the dependence of the response on contextual cues that are only present in the artificial in vitro environment. In one previous in vivo study [16] all-trans-retinoic acid upregulated TGF-β expression in rats, with kinetics and isoform selectivity that varied with the target tissue. However, the rats were vitamin A-deficient, and it is not known whether the same effects would be seen in vitamin A-replete animals, such as were used in the present study, or whether the response would vary with the specific retinoid used.\nThere are some data that support an effect of tamoxifen on upregulation of TGF-βs in vivo in humans. Three months of tamoxifen treatment was shown to cause a consistent induction in extracellular TGF-β in breast cancer biopsies, when compared with pretreatment biopsies from the same patients [23]. Furthermore, complex effects of tamoxifen on induction of TGF-β2 in the plasma of patients with metastatic breast cancer have been described [24]. It is possible that tamoxifen is only effective in inducing TGF-β in the context of a tumor, and not in normal or initiated tissue, which was the subject of the present study. This issue could be reassessed in preclinical models using the same agents to treat established proliferative intraepithelial neoplasia. However, for ease of tissue acquisition, an optimal surrogate end-point biomarker in a prevention setting needs to be modulated in normal or premalignant tissues.","divisions":[{"label":"title","span":{"begin":0,"end":31}},{"label":"p","span":{"begin":32,"end":775}}],"tracks":[{"project":"Colil","denotations":[{"id":"T73","span":{"begin":117,"end":119},"obj":"1698443"},{"id":"T74","span":{"begin":120,"end":122},"obj":"1985102"},{"id":"T75","span":{"begin":1217,"end":1219},"obj":"7553618"},{"id":"T76","span":{"begin":1217,"end":1219},"obj":"7553618"},{"id":"T77","span":{"begin":395,"end":397},"obj":"1879351"},{"id":"T78","span":{"begin":1070,"end":1072},"obj":"1322240"},{"id":"T79","span":{"begin":123,"end":125},"obj":"2879636"},{"id":"T80","span":{"begin":126,"end":128},"obj":"2519621"},{"id":"T81","span":{"begin":395,"end":397},"obj":"1879351"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/docs/sourcedb/PubMed/sourceid/"}],"attributes":[{"subj":"T73","pred":"source","obj":"Colil"},{"subj":"T74","pred":"source","obj":"Colil"},{"subj":"T75","pred":"source","obj":"Colil"},{"subj":"T76","pred":"source","obj":"Colil"},{"subj":"T77","pred":"source","obj":"Colil"},{"subj":"T78","pred":"source","obj":"Colil"},{"subj":"T79","pred":"source","obj":"Colil"},{"subj":"T80","pred":"source","obj":"Colil"},{"subj":"T81","pred":"source","obj":"Colil"}]}],"config":{"attribute types":[{"pred":"source","value type":"selection","values":[{"id":"Colil","color":"#ecb793","default":true}]}]}}