Unknown,Transcriptomics,Genomics,Proteomics

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Gene expression profile of epithelial ovarian tumor tissue of a transgenic mouse model compared to normal mouse ovary tissue

ABSTRACT: The etiology of ovarian cancer is poorly understood, mainly due to the lack of an appropriate experimental model for studying the onset and progression of this disease. We have created a mouse model termed ERalpha d/d in which a conditional deletion of estrogen receptor alpha (ERalpha) gene occurred in the anterior pituitary, but ERalpha expression remained intact in the hypothalamus and the ovary. The loss of negative-feedback regulation by estrogen (E) at the level of the pituitary led to elevated production of luteinizing hormone (LH) by this tissue. Hyperstimulation of ovarian cells by LH resulted in increased steroidogenesis, leading to high circulating levels of progesterone, testosterone and E. The ERalpha d/d mice exhibited formation of palpable ovarian epithelial tumors starting at 5 months of age, and by 12 months, most mice carrying these tumors died. Besides proliferating epithelial cells, these tumors also contained an expanded population of stromal cells, which express P450 aromatase suggesting that these cells acquired the ability to synthesize E. In ERalpha d/d mice, in response to the E produced by the stromal cells, the ERalpha signaling is accentuated in the ovarian epithelial cells, triggering increased ERalpha-dependent gene expression, abnormal cell proliferation, and tumorigenesis. The ERalpha d/d animal model of ovarian epithelial tumorigenesis will serve as a powerful tool for exploring the involvement of E-dependent signaling pathways in the etiology of ovarian cancer. To identify aberrantly regulated genes in epithelial ovarian tumors, we performed gene expression profling of ovarian tumor tissue isolated from ERaplha d/d mice and normal ovary tissue isolated from ERaplha f/f control mice. The ERalpha d/d mouse model was created via conditional deletion of ERalpha by employing the Cre-LoxP strategy. Transgenic mice expressing Cre recombinase under the control of progesterone receptor (PR) promoter, termed PR-cre mice, were crossed with mice harboring the M-bM-^@M-^XfloxedM-bM-^@M-^Y ERalpha gene (ERalpha f/f) to create the ERalpah d/d mice in which the ERalpha gene is deleted in cells expressing PR. Ovarian tumor tissue was isolated from ERalpha d/d mice and normal ovary tissue was isolated from ERalpha f/f mice at 5 months and 10 months of age. Tissues were snap frozen and total RNA was isolated. Total RNA was pooled from 3 mice for each sample subjected to microarray analysis.

ORGANISM(S): Mus musculus

SUBMITTER: Mary Laws

PROVIDER: E-GEOD-39402 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Embryo implantation into a receptive endometrium is tightly regulated by a variety of maternal factors, including cytokines, growth factors and transcription factors. Previous studies identified the leukaemia inhibitory factor (LIF), produced in uterine glands, as an essential factor for implantation. It was shown that LIF acts via its cell surface receptor to activate the transcription factor STAT3 in the uterine epithelial cells. However, the mechanisms via which STAT3 promotes uterine receptivity remain unknown. To address the molecular pathways regulated by STAT3 in the uterus, we created mice in which Stat3 gene is conditionally inactivated in uterine epithelium. These mutant mice are infertile due to implantation failure and exhibit a lack of embryo attachment to the luminal epithelium. Gene expression profiling of the epithelial tissue impaired in STAT3 activation revealed dysregulated expression of specific components of junctional complexes, including E-cadherin, M-NM-2-catenin, and claudins, which critically regulate epithelial cell polarity and embryo attachment. Additionally, mice lacking functional epithelial STAT3 showed markedly reduced stromal proliferation and differentiation, indicating that this transcription factor controls stromal function via a paracrine mechanism. The stromal defect arose from a drastic reduction in the production of several members of the epidermal growth factor (EGF) family in luminal epithelium of mutant uteri and consequent lack of activation of EGF receptor signaling and mitotic activity in the stromal cells. Collectively, our results uncovered intricate signaling networks operating downstream of STAT3 in uterine epithelium that regulate epithelial cell polarity, and stromal proliferation and differentiation, which are critical determinants of successful implantation. To identify the downstream targets of STAT3 in mouse uterine epithelial cells during pregnancy, we performed gene expression profling of mouse uterine epithelial cells on day 4 of pregnancy between Stat3 flox control and SW d/d mice. This led to the identification of several junctional molecules (Claudins and Catenins) that are negatively regulated by STAT3 at the time of implantation. Mouse uteirne epithelial cells were isolated from control and knockout mice on the morning of day 4 of pregnancy. (n=3 for each sample), pooled total RNA from these cells was then hybridized to high density affymetrix microarrays according to the Affymetrix protocol (Mouse Genome 430A 2.0 Array) .

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Gene expression profile of epithelial ovarian tumor tissue of a transgenic mouse model compared to normal mouse ovary tissue

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