Unknown,Transcriptomics,Genomics,Proteomics

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Response of the inguinal mammary gland tissue transcriptome to 17B-estradiol in 12- to 13-week-old virgin mice

ABSTRACT: Different strategies may be used to draw conclusions from the data generated by DNA microarrays in our study of the effect of estradiol (E2) on the transcriptome of the mammary gland of mice. We selected two strategies: the first one involving a classification by cellular process of regulated genes, and the second one taking advantage of gene expression profile over a time course of treatment. We also used two standardization methods, MAS5.0 and RMA, in order to assess their similarities and differences leading us to a better understanding of their impact on the results. In comparing expression patterns of regulated genes by E2, we observed that there are good similarities between gene expression profiles obtained by MAS5.0 and RMA. However, when the ratio between signal intensities of treatment and control is low, differences between data normalized by MAS 5.0 and RMA are more apparent, i.e. where the discrimination between biological and technical variability is the least obvious. Keywords: Time course Mammary gland tissue samples were obtained in gonadectomized (GDX) animals treated with vehicle (control group), or injected with E2 (0.05 M-BM-5g mg/mouse) at 1, 3, 6, 12, 18 and 24h prior to necropsy.

ORGANISM(S): Mus musculus

SUBMITTER: Ezequiel Calvo

PROVIDER: E-GEOD-11858 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:The efficacy and exceptionally good tolerance of estrogen blockade in the treatment of breast cancer is well recognized but novel agents are required, especially to take advantage of the multiple consecutive responses obtained in breast cancer progressing following previous hormone therapy, thus delaying the use of cytotoxic chemotherapy with its usually serious side effects. Acolbifene (ACOL) is a novel and unique antiestrogen completely free of estrogen-like activity in both the mammary gland and uterus while preventing bone loss. From the preclinical and clinical data so-far available, this new antiestrogen represents a unique opportunity for a highly potent and specific blockade of estrogen action in the mammary gland and uterus while exerting estrogen-like beneficial effects in other tissues (selective estrogen receptor modulator or SERM activity). In order to better understand the specificity of action of acolbifene, we have used Affymetrix GeneChips containing 45,000 probe sets to analyze 34,000 genes to determine the specificity of this compound compared to the pure antiestrogen fulvestrant, as well as the mixed antagonists/agonists tamoxifen and raloxifene to block the effect of estradiol (E2) and to induce effects of their own on gene expression in the mouse mammary gland. The genes modulated by E2 were those identified in two separate experiments and validated by quantitative real-time PCR (Q_RT-PCR). Three hours after the single subcutaneous injection of E2 (0.05 ug), the simultaneous administration of acolbifene, fulvestrant, tamoxifen and raloxifene blocked by 98%, 62%, 43% and 92% the number of E2-upregulated genes, respectively. On the other hand, 70%, 10%, 25% and 55% of the genes down-regulated by E2 were blocked by the same compounds. Acolbifene was also the compound which, when used alone, modulated the smallest number of genes also influenced by E2, namely 4%, thus possibly explaining the potent tumoricidal action of this compound in human breast cancer xenografts where 61% of tumors disappeared, thus bringing a new paradigm in the hormonal therapy of breast cancer. Female C57BL6 mice were ovariectomized (OVX). One week after OVX, mice were treated with EM-652.HCl (acolbifene), tamoxifen citrate, raloxifene or ICI 182780 (fulvestrant). Compounds were administered to OVX mice or to OVX mice simultaneously treated with 17b-estradiol (E2). Control groups received an injection of the vehicle alone. All animals were sacrificed after 3h of treatment.Mammary glands from all mice of the same group were collected and pooled. Total mRNA was isolated and converted to biotinylated cRNA.A microarray analysis was performed using Murine U74Av2 Affymetrix microarrays.

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Response of the inguinal mammary gland tissue transcriptome to 17B-estradiol in 12- to 13-week-old virgin mice

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