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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
2001-5-23
pubmed:abstractText
Despite the widespread clinical use of tamoxifen as a breast cancer prevention agent, the molecular mechanism of tamoxifen chemoprevention is poorly understood. Abnormal expression of p53 is felt to be an early event in mammary carcinogenesis. We developed an in vitro model of early breast cancer prevention to investigate how tamoxifen and 4-hydroxytamoxifen may act in normal human mammary epithelial cells (HMECs) that have acutely lost p53 function. p53 function was suppressed by retrovirally mediated expression of the human papillomavirus type 16 E6 protein. Tamoxifen, but not 4-hydroxytamoxifen, rapidly induced apoptosis in p53(-) HMEC-E6 cells as evidenced by characteristic morphologic changes, annexin V binding, and DNA fragmentation. We observed that a decrease in mitochondrial membrane potential, mitochondrial condensation, and caspase activation preceded the morphologic appearance of apoptosis in tamoxifen-treated early passage p53(-) HMEC-E6 cells. p53(-) HMEC-E6 cells rapidly developed resistance to tamoxifen-mediated apoptosis within 10 passages in vitro. Resistance to tamoxifen in late passage p53(-) HMEC-E6 cells correlated with an increase in mitochondrial mass and a lack of mitochondrial depolarization and caspase activation following tamoxifen treatment. We hypothesize that an early event in the induction of apoptosis by tamoxifen involves mitochondrial depolarization and caspase activation, and this may be important for effective chemoprevention.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
16
pubmed:volume
276
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5384-94
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:11094056-Anticarcinogenic Agents, pubmed-meshheading:11094056-Apoptosis, pubmed-meshheading:11094056-Breast, pubmed-meshheading:11094056-Caspases, pubmed-meshheading:11094056-Cell Culture Techniques, pubmed-meshheading:11094056-Cell Division, pubmed-meshheading:11094056-Cell Line, pubmed-meshheading:11094056-Chromatography, High Pressure Liquid, pubmed-meshheading:11094056-Epithelial Cells, pubmed-meshheading:11094056-Estrogen Antagonists, pubmed-meshheading:11094056-Female, pubmed-meshheading:11094056-Humans, pubmed-meshheading:11094056-Membrane Potentials, pubmed-meshheading:11094056-Mitochondria, pubmed-meshheading:11094056-Oncogene Proteins, Viral, pubmed-meshheading:11094056-Repressor Proteins, pubmed-meshheading:11094056-Tamoxifen, pubmed-meshheading:11094056-Tumor Suppressor Protein p53
pubmed:year
2001
pubmed:articleTitle
Tamoxifen but not 4-hydroxytamoxifen initiates apoptosis in p53(-) normal human mammary epithelial cells by inducing mitochondrial depolarization.
pubmed:affiliation
Program in Chemical Biology and Division of Medical Oncology, Duke University, Durham, NC 27710, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't