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Tamoxifen induces expression of immune-response related genes in cultured NHMEC

ABSTRACT: 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-α (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.

ORGANISM(S): Homo sapiens

SUBMITTER: Schild-Hay LJ

PROVIDER: S-ECPF-GEOD-13476 | biostudies-other | 2009 Feb

REPOSITORIES: biostudies-other

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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:BackgroundEstrogen receptors alpha (ER) are implicated in many types of female cancers, and are the common target for anti-cancer therapy using selective estrogen receptor modulators (SERMs, such as tamoxifen). However, cell-type specific and patient-to-patient variability in response to SERMs (from suppression to stimulation of cancer growth), as well as frequent emergence of drug resistance, represents a serious problem. The molecular processes behind mixed effects of SERMs remain poorly understood, and this strongly motivates application of systems approaches. In this work, we aimed to establish a mathematical model of ER-dependent gene expression to explore potential mechanisms underlying the variable actions of SERMs.ResultsWe developed an equilibrium model of ER binding with 17β-estradiol, tamoxifen and DNA, and linked it to a simple ODE model of ER-induced gene expression. The model was parameterised on the broad range of literature available experimental data, and provided a plausible mechanistic explanation for the dual agonism/antagonism action of tamoxifen in the reference cell line used for model calibration. To extend our conclusions to other cell types we ran global sensitivity analysis and explored model behaviour in the wide range of biologically plausible parameter values, including those found in cancer cells. Our findings suggest that transcriptional response to tamoxifen is controlled in a complex non-linear way by several key parameters, including ER expression level, hormone concentration, amount of ER-responsive genes and the capacity of ER-tamoxifen complexes to stimulate transcription (e.g. by recruiting co-regulators of transcription). The model revealed non-monotonic dependence of ER-induced transcriptional response on the expression level of ER, that was confirmed experimentally in four variants of the MCF-7 breast cancer cell line.ConclusionsWe established a minimal mechanistic model of ER-dependent gene expression, that predicts complex non-linear effects in transcriptional response to tamoxifen in the broad range of biologically plausible parameter values. Our findings suggest that the outcome of a SERM's action is defined by several key components of cellular micro-environment, that may contribute to cell-type-specific effects of SERMs and justify the need for the development of combinatorial biomarkers for more accurate prediction of the efficacy of SERMs in specific cell types.

Project description:Leaf-cutting ants are evolutionary derived social insects with elaborated division of labor and tremendous colony sizes with millions of workers. Their social organization is mainly based on olfactory communication using different pheromones and is promoted by a pronounced size-polymorphism of workers that perform different tasks within the colony. The size polymorphism and associated behaviors are correlated to distinct antennal lobe (AL) phenotypes. Two worker phenotypes differ in number of olfactory glomeruli in the AL and the presence or absence of an extremely large glomerulus (macroglomerulus), involved in trail-pheromone reception. The males' AL contains three macroglomeruli which are presumably involved in detection of sex-pheromone components. We investigated the antennal transcriptome data of all major castes (males, queens and workers) and two worker subcastes (large and tiny workers). In order to identify putative odorant receptor genes involved in pheromone detection, we identified differentially expressed odorant receptor genes (OR-genes) using custom microarrays. In total, we found 185 OR-gene fragments that are clearly related to ORs and we identified orthologs for 70 OR-genes. Among them one OR-gene differs in relative expression between the two worker subcastes by a factor of >3 and thus is a very promising candidate gene for the trail-pheromone receptor. Using the relative expression of OR-genes in males versus queens, we identified 2 candidates for sex-pheromone receptor genes in males. In addition, we identified genes from all other chemosensory related gene families (13 chemosensory protein genes, 8 odorant binding protein genes, 2 sensory-neuron membrane protein genes, 7 ionotropic receptor genes, 2 gustatory receptor genes), and we found ant-specific expansions in the chemosensory protein gene family. In addition, a large number of genes involved in immune defense exhibited differential expression across the three different castes, and some genes even between the two worker subcastes.

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Tamoxifen induces expression of immune-response related genes in cultured NHMEC

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