title: In vitro cytotoxicity of 4'-OH-tamoxifen and estradiol in human endometrial adenocarcinoma cells HEC-1A and HEC-1B.
abstract: Tamoxifen (TAM), used to treat estrogen receptor (ER)-positive breast cancer, is a well known estrogen antagonist in the breast, but a partial estrogen agonist in the endometrium. In addition, TAM metabolites, such as 4'-hydroxy-tamoxifen (4-OH-TAM), have been shown to be more potent than the parent compound. The objective of this study was to determine the effects of 4-OH-TAM and estradiol (E2) on two human endometrial adenocarcinoma cell lines, HEC-1B and HEC-1A. When HEC-1B cells were treated with lower concentrations (10-1,000 nM) of 4-OH-TAM or E2 for 1-3 days, no significant difference in the percentage of cell survival was observed among the varying concentrations. At higher 4-OH-TAM or E2 concentrations (1-100 µM), HEC-1B and HEC-1A cells responded similarly with an obvious decrease in cell growth noted at 10 and 100 µM 4-OH-TAM and 100 µM E2. In order to address the observed cell death, DNA laddering was performed at various time intervals with 4-OH-TAM (10 µM) or E2 (10 or 50 µM). DNA gel electrophoresis failed to show the typical laddering pattern (180-200 bp) observed in apoptosis. Furthermore, western blot analysis of caspase-8 and -3 failed to demonstrate caspase activity. These results suggest that apoptosis was not the underlying cellular mechanism of cell death. Due to the lack of apoptotic markers, a cytotoxic (cell death) effect was differentiated from a cytostatic (growth inhibition) effect confirming that cell death had occurred. In summary, micromolar concentrations of 4-OH-TAM induced a non-apoptotic cytotoxic effect in the endometrium; however further studies are needed to elucidate the cytotoxic pathway being utilized.
authors.affiliation: Department of Biology, Southwestern University, Georgetown, TX 78626, USA.
authors.forename: Maria E
authors.initials: ME
authors.lastname: Cuevas
authors.affiliation: Department of Biology, Southwestern University, Georgetown, TX 78626, USA.
authors.forename: Tracey E
authors.initials: TE
authors.lastname: Lindeman
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D045744:Cell Line, Tumor / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D016889:Endometrial Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology; D013629:Tamoxifen / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen; C016601:afimoxifene; D004958:Estradiol; D053148:Caspase 3; D053181:Caspase 8