Project description:Administration of tamoxifen (TAM) as breast cancer adjuvant therapy is associated with a 50% reduction in breast cancer risk and an increase in endometrial cancer risk. To investigate underlying mechanisms, we documented TAM-induced gene expression changes in cultured normal human mammary epithelial cell (NHMEC) strains (numbered 5, 16 and 40) established from tissue taken at reduction mammoplasty from three different individuals. Cells exposed to 0 and 10 uM TAM for 48 hours were evaluated for survival, TAM-DNA adduct formation by TAM-DNA chemiluminescence immunoassay (CIA), and gene expression changes using DNA-oligonucleotide microarray and real time reverse transcriptase-PCR (RT-PCR). At 48 hr, cells exposed to 10 uM TAM were 78% viable, respectively, and there were no measurable TAM-DNA adducts (limit of detection [LOD] = 0.3 adducts/10^8 nucleotides). For microarray analysis, RNA was extracted from cells exposed on three occasions to 10 uM TAM and the corresponding oligonucleotide probes were labeled with fluorescent dyes and hybridized to NCI microarrays (>20,000 human genes). Expression changes of > 3-fold were considered significant, and by these criteria, thirteen genes were up-regulated and one was down-related in NHMEC strain 16, seventeen genes were up-regulated in strain 05, and eleven genes were up-regulated in strain and 40. Elements that were up-regulated in all three cell strains included several interferon-induced genes (IFITM1, IFIT1, IFNA1, MXI and GIP3), and a potassium ion channel (KCNJ1). No significant expression changes were found for genes related to estrogen or xenobiotic metabolism. RT-PCR revealed TAM-induced up-regulation of the five genes of interest, and interferon á (IFNA1), in all three NHMEC strains, with the exception of GIP3 and MX1, which were unchanged in strain 40. The magnitude of TAM-induced up-regulation ranked: strain 16 > strain 05> strain 40. The consistent induction of interferon-related genes in all three NHMEC strains suggests that, in addition to hormonal effects, TAM exposure may enhance immune response, through interferon induction, in normal breast tissue. RNA was extracted from three cell strains (NHMEC 98016, 98040 and 99005) and exposed on three separate occasions to 10 uM TAM. Comparisons were made using 16 arrays with 8 dye swaps for cell strain NHMEC 99005, 9 arrays with 4 dye swaps for NHMEC 98016, and 12 arrays with 6 dye swaps for NHMEC 98040.

Project description:Administration of tamoxifen (TAM) as breast cancer adjuvant therapy is associated with a 50% reduction in breast cancer risk and an increase in endometrial cancer risk. To investigate underlying mechanisms, we documented TAM-induced gene expression changes in cultured normal human mammary epithelial cell (NHMEC) strains (numbered 5, 16 and 40) established from tissue taken at reduction mammoplasty from three different individuals. Cells exposed to 0 and 10 uM TAM for 48 hours were evaluated for survival, TAM-DNA adduct formation by TAM-DNA chemiluminescence immunoassay (CIA), and gene expression changes using DNA-oligonucleotide microarray and real time reverse transcriptase-PCR (RT-PCR). At 48 hr, cells exposed to 10 uM TAM were 78% viable, respectively, and there were no measurable TAM-DNA adducts (limit of detection [LOD] = 0.3 adducts/10^8 nucleotides). For microarray analysis, RNA was extracted from cells exposed on three occasions to 10 uM TAM and the corresponding oligonucleotide probes were labeled with fluorescent dyes and hybridized to NCI microarrays (>20,000 human genes). Expression changes of > 3-fold were considered significant, and by these criteria, thirteen genes were up-regulated and one was down-related in NHMEC strain 16, seventeen genes were up-regulated in strain 05, and eleven genes were up-regulated in strain and 40. Elements that were up-regulated in all three cell strains included several interferon-induced genes (IFITM1, IFIT1, IFNA1, MXI and GIP3), and a potassium ion channel (KCNJ1). No significant expression changes were found for genes related to estrogen or xenobiotic metabolism. RT-PCR revealed TAM-induced up-regulation of the five genes of interest, and interferon á (IFNA1), in all three NHMEC strains, with the exception of GIP3 and MX1, which were unchanged in strain 40. The magnitude of TAM-induced up-regulation ranked: strain 16 > strain 05> strain 40. The consistent induction of interferon-related genes in all three NHMEC strains suggests that, in addition to hormonal effects, TAM exposure may enhance immune response, through interferon induction, in normal breast tissue.

Project description:This model is described in the article: Kinetics of histone gene expression during early development of Xenopus laevis. Koster JG, Destrée OH and Westerhoff HV. J Theor Biol. 1988 Nov 21;135(2):139-67. PMID: 3267765 Abstract: Using literature data for transcriptional and translational rate constants, gene copy numbers, DNA concentrations, and stability constants, we have calculated the expected concentrations of histones and histone mRNA during embryogenesis of Xenopus laevis. The results led us to conclude that: (i) for X. laevis the gene copy number of the histone genes is too low to ensure the synthesis of sufficient histones during very early development, inheritance from the oocyte of either histone protein or histone mRNA (but not necessarily both) is necessary; (ii) from the known storage of histones in the oocyte and the rates of histone synthesis determined by Adamson and Woodland (1977), there would be sufficient histones to structure the newly synthesized DNA up to gastrulation but not thereafter (these empirical rates of histone synthesis may be underestimates); (iii) on the other hand, the amount of H3 mRNA recently observed during early embryogenesis (Koster, 1987, Koster et al., 1988) could direct a higher and sufficient synthesis of H3 protein, also after gastrulation. We present a quantitative model that accounts both for the observed H3 mRNA concentration as a function of time during embryogenesis and for the synthesis of sufficient histones to structure the DNA throughout early embryogenesis. The model suggests that X. laevis exhibits a major (i.e. some 14-fold) reduction in transcription of histone genes approximately 11 hours after fertilization. This reduction could be due to a decrease in the number of transcribed histone genes, a decreased rate constant of transcription with continued transcription of all the histone genes, and/or a reduction in the time during the cell cycle in which histone mRNA synthesis takes place. Alternatively, the histone mRNA stability might decrease approximately 16-fold 11 hours after fertilization. This model originates from BioModels Database: A Database of Annotated Published Models. It is copyright (c) 2005-2011 The BioModels.net Team. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information. In summary, you are entitled to use this encoded model in absolutely any manner you deem suitable, verbatim, or with modification, alone or embedded it in a larger context, redistribute it, commercially or not, in a restricted way or not.. To cite BioModels Database, please use: Li C, Donizelli M, Rodriguez N, Dharuri H, Endler L, Chelliah V, Li L, He E, Henry A, Stefan MI, Snoep JL, Hucka M, Le Novère N, Laibe C (2010) BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. BMC Syst Biol., 4:92.

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Tamoxifen transcriptional regulation in normal human mammary epithelial cells (NHMEC)

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