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Identification of hormone interactions important for mammary gland proliferation and gene expression

ABSTRACT: Using our unique and authentic animal model, the pig, we determined which genes in the normal mammary gland are regulated in response to different combinations of the ovarian hormones estrogen and progesterone and the pituitary hormone prolactin. We surgically removed ovaries from 32 pigs to deplete endogenous estrogen and progesterone, and administered bromocriptine to suppress endogenous prolactin. Pigs were treated with all combinations of estrogen, progesterone and bromocriptine and/or haloperidol (to induce prolactin secretion), in a factorial design. Affymetrix arrays were used to analyze RNA from the mammary glands of these pigs and we found that estrogen, prolactin and the interaction of estrogen*prolactin were the primary regulators of gene expression in the mammary gland. This is in contrast to rodents where progesterone has an important role in ductal elongation and branching. Functional enrichment analyses suggest that estrogen promotes cell division while prolactin stimulates elements of fatty acid metabolism and an inflammatory response (in addition to milk protein genes). These results concur with phenotypic changes where estrogen, prolactin and estrogen*prolactin were the most important regulators of morphological development, cell proliferation and steroid receptor expression. Regression analysis of expression data against the rate of cell proliferation in all 32 pigs identified 1669 genes correlated with proliferation (FDR a=0.01). Regression analysis of expression data against proliferation in the 16 pigs treated with E identified 71 genes correlated with proliferation. 29 genes were common to both lists and also regulated by estrogen, and of these 16 have known functions in the cell cycle while the other 13 have never been associated with estrogen regulated mammary gland growth or cell proliferation. Twenty six of these genes were more highly correlated with proliferation than MKI67 (Ki67).

ORGANISM(S): Sus scrofa

PROVIDER: GSE106212 | GEO | 2020/10/25

REPOSITORIES: GEO

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Project description:Objective: Bromocriptine treatment has been shown to reduce menstrual bleeding and pain in women with adenomyosis in a pilot clinical trial. The underlying mechanism contributing to the treatment effect is however unknown. This study was to explore the effect of bromocriptine on the proliferation and migration properties of the endometrium in women with adenomyosis, by assessing cellular and molecular changes after six months of vaginal bromocriptine treatment. Methods: Endometrial specimens were collected during the proliferative phase from women with adenomyosis (n=6) before (baseline) and after six months of vaginal bromocriptine treatment. Immunohistochemistry was used to determine changes in the protein expression of Ki67 in the endometrium. Primary endometrial stromal cells isolated at baseline were expanded in vitro and exposed to different doses of bromocriptine to determine the optimal half-maximum inhibitory concentration (IC50) using CellTiter-Blue® Cell Viability Assay. Cell proliferation was assessed by bromodeoxyuridine ELISA assay and Ki67 gene expression was checked by real-time PCR. The migratory ability of endometrial stromal cells was determined by wound healing and transwell migration assays. Small RNA sequencing was applied on tissues collected from women with adenomyosis before and after bromocriptine treatment to identify differentially expressed micro RNAs. Bioinformatic methods were used for target gene prediction and the identification of biological pathways. Results: Vaginal bromocriptine treatment reduced the Ki67 protein expression in the endometrium of women with adenomyosis and did not change the prolactin mRNA expression and protein concentration of prolactin in endometrial tissues. Bromocriptine significantly inhibited the proliferative and migrative abilities of endometrial stromal cells derived from women with adenomyosis in vitro. Moreover, small RNA sequencing revealed 27 differentially expressed micro RNAs (miRNAs) between the endometrium of women with adenomyosis before and after six months of vaginal bromocriptine treatment. KEGG pathway analysis on targeted genes of 27 miRNAs showed that several signaling pathways associated with cell proliferation and apoptosis were enriched after treatment. Conclusion: Bromocriptine treatment exhibits an anti-proliferative effect in the endometrium of women with adenomyosis in vivo and in vitro. Bromocriptine might inhibit the proliferation of endometrial tissue in adenomyosis in part through the regulation of dysregulated microRNAs and proliferation-associated signaling pathways.

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.

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Identification of hormone interactions important for mammary gland proliferation and gene expression

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