Unknown,Transcriptomics,Genomics,Proteomics

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Molecular Analysis of the Vaginal Response to Estrogens in the Ovariectomized Rat and Postmenopausal Woman

ABSTRACT: Background. Vaginal atrophy (VA) is the thinning of the vaginal epithelial lining, typically the result of lowered estrogen levels during menopause. Some of the consequences of VA include increased susceptibility to bacterial infection, pain during sexual intercourse, and vaginal burning or itching. Although estrogen treatment is highly effective, alternative therapies are also desired for women who are not candidates for hormone replacement therapy (HRT). The ovariectomized (OVX) rat is widely accepted as an appropriate animal model for many estrogen-dependent responses in humans; however, since reproductive biology can vary significantly between mammalian systems, this study examined how well the OVX rat recapitulates human biology at the transcriptional level. This report describes an analysis of expression profiling data, comparing the responses of rat and human vaginae to estrogen treatment. Results. The level of differential expression between pre- vs. post- estrogen treatment was calculated for each of the human and OVX rat datasets. Probe sets corresponding to orthologous rat and human genes were mapped to each other using NCBI Homologene. A positive correlation was observed between the rat and human responses to estrogen. Genes belonging to several biological pathways and GO categories were similarly differentially expressed in rat and human. A large number of the coordinately regulated biological processes are already known to be involved in human VA, such as inflammation, epithelial development, and EGF pathway activation. Conclusions. At the transcriptional level, there is evidence of significant overlap of the effects of estrogen treatment between the OVX rat and human VA samples. Keywords: Disease State Analysis: Animal Model Validation We analyzed vaginal biopsies from 19 woman pre and post 3 month estradiol treatment and compared to OVX rats treated with E2 for 6 hr, 3 days or 5 days (N=5)

ORGANISM(S): Rattus norvegicus

SUBMITTER: Scott Jelinsky

PROVIDER: E-GEOD-11622 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Molecular analysis of the vaginal response to estrogens in the ovariectomized rat and postmenopausal woman.

Jelinsky Scott A SA Choe Sung E SE Crabtree Judy S JS Cotreau Monette M MM Wilson Ewa E Saraf Kathryn K Dorner Andrew J AJ Brown Eugene L EL Peano Bryan J BJ Zhang Xiaochun X Winneker Richard C RC Harris Heather A HA

BMC medical genomics 20080625

<h4>Background</h4>Vaginal atrophy (VA) is the thinning of the vaginal epithelial lining, typically the result of lowered estrogen levels during menopause. Some of the consequences of VA include increased susceptibility to bacterial infection, pain during sexual intercourse, and vaginal burning or itching. Although estrogen treatment is highly effective, alternative therapies are also desired for women who are not candidates for post-menopausal hormone therapy (HT). The ovariectomized (OVX) rat ...[more]

PMID: 18578861

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Project description:Despite an abundance of evidence to the contrary from animal studies, large clinical trials on humans have shown that estrogen administered to post-menopausal women increases the risk of cardiovascular disease. However, timing may be everything, as estrogen is often administered immediately after ovariectomy (ovx) in animal studies, while estrogen administration in human studies occurred many years post-menopause. This study investigates the discrepancy by administering 17ß-estradiol (E2) in a slow-release capsule to Norway Brown rats both immediately following ovx and 9 weeks post-ovx (Late), and studying differences in gene expression between these 2 groups as compared to age-matched ovx and sham operated animals. Two different types of microarray were used to analyze the left ventricles from these groups: an Affymetrix array (2 samples/group, each sample contained total RNAs pooled from 3 rats) and an Inflammatory Cytokines and Receptors PCR array (N=4 /group). Key genes were analyzed by western blotting. Ovx without replacement led to an increase in caspase 3, caspase 9, calpain 2, MMP9, and TNFα. Caspase 6, STAT3, and CD11b increased in the Late group, while TIMP2, MMP14, and collagen I α1 were decreased. MADD and fibronectin were increased in both Ovx and Late. TNFα protein levels increased with Late replacement. Many of these changes were prevented by early E2 replacement. These findings suggest that increased TNFα may be involved in some of the deleterious effects of delayed E2 administration seen in human studies. The rats were randomly assigned to four groups: Sham, Ovx, Early estrogen group, and Late estrogen group. The Sham rats were anesthetized, had their body cavities opened and then immediately closed with no tissue removal; the Ovx group underwent ovariectomy. The Early estrogen group after ovariectomy had a 0.5 mg 17-β estradiol 90-day slow release pellet (Innovative Research of America, Sarasota, FL) implanted subcutaneously in the back of the neck at the time of surgery. The Late estrogen group underwent ovariectomy and had a subcutaneous estrogen pellet placed, as above, at 9 weeks post-ovx. RNA target was prepared according to the instructions of the manufacturer (Affymetrix). For each RNA sample, good-quality total RNA from three rat hearts were pooled together in equal amounts and used to synthesize double-strand cDNA using a one-cycle cDNA synthesis kit (Affymetrix, P/N 900431). This approach allows repetitive analysis of all groups by the array in a group representative and cost effective manner, and has been used effectively by other investigators. Two pooled RNA samples were prepared for each group, and all the RNA samples were proceeded with Affymetrix expression chip analysis.

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.

Dataset Information

Molecular Analysis of the Vaginal Response to Estrogens in the Ovariectomized Rat and Postmenopausal Woman

Publications

Molecular analysis of the vaginal response to estrogens in the ovariectomized rat and postmenopausal woman.

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