Project description:Clinical studies have linked use of progestins (synthetic progesterone (P4)) to breast cancer risk. However, little is understood regarding the role native P4, signaling through the progesterone receptor (PR), plays in formation of breast tumors. Studies published by our lab highlighted a link between PR and immune signaling pathways, suggesting PR induces PR to repress the interferon signaling pathway. Given these findings, we sought to investigate whether P4/PR drive immunomodulation in the mammary gland and development of mammary gland tumors. We found that mice treated with P4 displayed changes in the mammary gland suggesting inhibited immune response compared to placebo-treated mice. Furthermore, transgenic mice with PR overexpression demonstrated decreased numbers of immune cell populations in their mammary gland, lymph nodes, and spleens. Upon long-term monitoring, we determined that multi-parous PR overexpressing mice developed significantly more mammary gland tumors than control mice. Additionally, tumors of PR overexpressing mice contained fewer infiltrating immune cells. Finally, RNA sequencing analysis of tumor samples revealed that immune-related gene signatures were enriched in tumors of control mice compared to tumors of PR overexpressing mice. Together, these findings provide a novel mechanism behind P4-mediated promotion of mammary gland tumor development and provide rationale to investigate anti-progestin treatment to promote immune-mediated elimination of mammary gland tumors.
Project description:Progesterone (P) acting through its cognate nuclear receptors (PRs) plays an essential role in driving pregnancy-associated branching morphogenesis of the mammary gland. However, the fundamental mechanisms, including global cistromic and acute genomic transcriptional responses that are required to elicit active branching morphogenesis in response to P, have not been elucidated. We used microarray analysis to identify global gene expression signatures that are acutely regulated by PRs in the mouse mammary gland after acute P treatment. Mammary gland gene expression data from 10-week-old ovariectomized wildtype and progesterone receptor null mice treated subcutaneously with 17β-Estradiol for 24 hours and then 17β-Estradiol plus Progesterone for 8 or 24 hours. Three replicate pools were tested with three mice per pool.
Project description:The present experiments were performed to determine the roles of estrogen receptors α and β (ERα and ERβ) in normal and neoplastic development in the mouse mammary gland. In wild-type mice, in vivo administration of estradiol (E) + progesterone (P) stimulated mammary ductal growth and alveolar differentiation. Mammary glands from mice in which the ERβ gene has been deleted (βERKO mice) demonstrated normal ductal growth and differentiation in response to E + P. By contrast, mammary glands from mice in which the ERα gene has been deleted (αERKO mice) demonstrated only rudimentary ductal structures that did not differentiate in response to E + P. EGF demonstrates estrogen-like activity in the mammary glands of αERKO mice: treatment of αERKO mice with EGF + P (without E) supported normal mammary gland development, induced expression of progesterone receptor (PR), and increased levels of G- protein-coupled receptor (GPR30) protein. Mammary gland development in βERKO mice treated with EGF + P was comparable to that of wild-type mice receiving EGF + P; EGF had no statistically significant effects on the induction of PR or expression of GPR30 in mammary glands harvested from either wild-type mice or βERKO mice. In vitro exposure of mammary glands to 7,12-dimethylbenz[a]anthracene (DMBA) induced preneoplastic mammary alveolar lesions (MAL) in glands from wild-type mice and βERKO mice, but failed to induce MAL in mammary glands from αERKO mice. Microarray analysis of DMBA-treated mammary glands identified 28 functional pathways whose expression was significantly different in αERKO mice versus both βERKO and wild-type mice; key functions that were differentially expressed in αERKO mice included cell division, cell proliferation, and apoptosis. The data demonstrate distinct roles for ERα and ERβ in normal and neoplastic development in the mouse mammary gland, and suggest that EGF can mimic the ERα-mediated effects of E in this organ.
Project description:The present experiments were performed to determine the roles of estrogen receptors M-NM-1 and M-NM-2 (ERM-NM-1 and ERM-NM-2) in normal and neoplastic development in the mouse mammary gland. In wild-type mice, in vivo administration of estradiol (E) + progesterone (P) stimulated mammary ductal growth and alveolar differentiation. Mammary glands from mice in which the ERM-NM-2 gene has been deleted (M-NM-2ERKO mice) demonstrated normal ductal growth and differentiation in response to E + P. By contrast, mammary glands from mice in which the ERM-NM-1 gene has been deleted (M-NM-1ERKO mice) demonstrated only rudimentary ductal structures that did not differentiate in response to E + P. EGF demonstrates estrogen-like activity in the mammary glands of M-NM-1ERKO mice: treatment of M-NM-1ERKO mice with EGF + P (without E) supported normal mammary gland development, induced expression of progesterone receptor (PR), and increased levels of G- protein-coupled receptor (GPR30) protein. Mammary gland development in M-NM-2ERKO mice treated with EGF + P was comparable to that of wild-type mice receiving EGF + P; EGF had no statistically significant effects on the induction of PR or expression of GPR30 in mammary glands harvested from either wild-type mice or M-NM-2ERKO mice. In vitro exposure of mammary glands to 7,12-dimethylbenz[a]anthracene (DMBA) induced preneoplastic mammary alveolar lesions (MAL) in glands from wild-type mice and M-NM-2ERKO mice, but failed to induce MAL in mammary glands from M-NM-1ERKO mice. Microarray analysis of DMBA-treated mammary glands identified 28 functional pathways whose expression was significantly different in M-NM-1ERKO mice versus both M-NM-2ERKO and wild-type mice; key functions that were differentially expressed in M-NM-1ERKO mice included cell division, cell proliferation, and apoptosis. The data demonstrate distinct roles for ERM-NM-1 and ERM-NM-2 in normal and neoplastic development in the mouse mammary gland, and suggest that EGF can mimic the ERM-NM-1-mediated effects of E in this organ. Gene expression of mammary gland organ culture and DMBA-induced lesions from 4 mouse strains.
Project description:To study the effect of pregnancy on mouse mammary epithelial subpopulations, epthelial cells derived from control or ovariectomized adult mice were isolated using fluorescence-activated cell sorting. After elimination of haematopoietic and endothelial cells, two distinct epithelial subpopulations were sorted using antibodies against CD29 and CD24. Based on the immunohistochemical phenotype, and in vivo and in vitro functional assays, these subpopulations were identified as mammary stem cell enriched (CD29hiCD24+) and luminal (CD29loCD24+) respectively (ref: Shackleton et al, Nature 2006). Microarray profiling was used to compare gene expression profiles of the two subpopulations isolated from ovariectomized and control mice. For each of two biological replicates, 6 FVB/NJ mice were ovariectomized at 8 weeks of age. 4 weeks after ovariectomy (Ovx) mammary gland from control or Ovx animals were collected and digested to obtain a single cell suspension. CD45-CD31-TER119- cells were then sorted based on the expression of cell surface markers CD24 and CD29. Similarly for two pools of control mice. There were also 4 technical replicates, to make 12 BeadChips in total.
Project description:Both ovarian and pituitary hormones are required for the pubertal development of the mouse mammary gland. Estradiol directs ductal elongation and branching within the adipose stroma of the adolescent mouse mammary gland, while progesterone leads to tertiary branching and alveolar development. The purpose of this investigation was to identify the estrogen-responsive genes that are associated with estrogen-stimulated ductal elongation and branching in the mouse mammary gland in the absence of other ovarian hormones. We also wanted to determine if estrogen-responsive gene regulation at early stages of ductal elongation (ie. when ductal growth was minimal) was similar to those regulated after significant ductal elongation had occurred. To identify estrogen-regulated genes, ovariectomized prepubertal mice were exposed to 17beta-estradiol for four weeks, and mammary gland global gene expression analyzed by microarray analysis at various points during this time course. We determined that while many genes are regulated in all weeks of treatment, there remained a subset of genes that was uniquely regulated at each time-point. This observation was reflected in the biological functions of these genes; some categories were represented in all weeks of treatment while others were specific to only certain time-points. We have also identified estradiol-responsive genes in the mouse mammary gland that co-express with Estrogen Receptor alpha in human breast cancer, which may represent novel effectors of estrogen action and/or biomarkers for the progression of estrogen-dependent cancers and other estrogen-driven diseases.