Decidualization denotes the transformation of endometrial stromal fibroblasts into specialized secretory decidual cells that provide a nutritive and immunoprivileged matrix essential for embryo implantation and placental development. In contrast to most mammals, decidualization of the human endometrium does not require embryo implantation. Instead, this process is driven by the postovulatory rise in progesterone levels and increasing local cAMP production. In response to falling progesterone levels, spontaneous decidualization causes menstrual shedding and cyclic regeneration of the endometrium. A growing body of evidence indicates that the shift from embryonic to maternal control of the decidual process represents a pivotal evolutionary adaptation to the challenge posed by invasive and chromosomally diverse human embryos. This concept is predicated on the ability of decidualizing stromal cells to respond to individual embryos in a manner that either promotes implantation and further development or facilitates early rejection. Furthermore, menstruation and cyclic regeneration involves stem cell recruitment and renders the endometrium intrinsically capable of adapting its decidual response to maximize reproductive success. Here we review the endocrine, paracrine, and autocrine cues that tightly govern this differentiation process. In response to activation of various signaling pathways and genome-wide chromatin remodeling, evolutionarily conserved transcriptional factors gain access to the decidua-specific regulatory circuitry. Once initiated, the decidual process is poised to transit through distinct phenotypic phases that underpin endometrial receptivity, embryo selection, and, ultimately, resolution of pregnancy. We discuss how disorders that subvert the programming, initiation, or progression of decidualization compromise reproductive health and predispose for pregnancy failure.

Forkhead box (FOX) proteins are multifaceted transcription factors that are responsible for fine-tuning the spatial and temporal expression of a broad range of genes both during development and in adult tissues. This function is engrained in their ability to integrate a multitude of cellular and environmental signals and to act with remarkable fidelity. Several key members of the FOXA, FOXC, FOXM, FOXO and FOXP subfamilies are strongly implicated in cancer, driving initiation, maintenance, progression and drug resistance. The functional complexities of FOX proteins are coming to light and have established these transcription factors as possible therapeutic targets and putative biomarkers for specific cancers.

In humans, the endometrium, the uterine mucosal lining, undergoes dynamic changes throughout the menstrual cycle and pregnancy. Despite the importance of the endometrium as the site of implantation and nutritional support for the conceptus, there are no long-term culture systems that recapitulate endometrial function in vitro. We adapted conditions used to establish human adult stem cell-derived organoid cultures to generate 3D cultures of normal and decidualised human endometrium. These organoids expand long-term, are genetically stable and differentiate following treatment with reproductive hormones. Single cells from both endometrium and decidua can generate a fully functional organoid. Transcript analysis confirmed great similarity between organoids and the primary tissue of origin. On exposure to pregnancy signals, endometrial organoids develop characteristics of early pregnancy. We also derived organoids from malignant endometrium, and so provide a foundation to study common diseases, such as endometriosis and endometrial cancer, as well as the physiology of early gestation.

Paclitaxel is used to treat breast cancers, but the mechanisms by which it induces apoptosis are poorly understood. Consequently, we have studied the role of the FoxO transcription factors in determining cellular response to paclitaxel. Western blotting revealed that in a panel of nine breast cancer cell lines expression of FoxO1a and FoxO3a correlated with the expression of the pro-apoptotic FoxO target Bim, which was associated with paclitaxel-induced apoptosis. In MCF-7 cells, which were paclitaxel-sensitive, the already high basal levels of FoxO3a and Bim protein increased dramatically after drug treatment, as did Bim mRNA, which correlated with apoptosis induction. This was not observed in MDA-231 cells, which expressed low levels of FoxOs and Bim. Gene reporter experiments demonstrated that in MCF-7 cells maximal induction of Bim promoter was dependent on a FoxO binding site, suggesting that FoxO3a is responsible for the transcriptional up-regulation of Bim. Gene silencing experiments showed that small interference RNA (siRNA) specific for FoxO3a reduced the levels of FoxO3a and Bim protein as well as inhibited apoptosis in paclitaxel-treated MCF-7 cells. Furthermore, siRNA specific for Bim reduced the levels of Bim protein and inhibited apoptosis in paclitaxel-treated MCF-7 cells. This is the first demonstration that up-regulation of FoxO3a by paclitaxel can result in increased levels of Bim mRNA and protein, which can be a direct cause of apoptosis in breast cancer cells.Breast cancer is one of the most common malignancies affecting women in the western world and arises following the accumulation of a series of somatic changes that serve to increase the rate of cellular proliferation and/or reduce the levels of apoptosis. These changes are often found to involve deregulation of key signal transduction pathways. Signal transduction pathways within the cell transmit the extracellular signals to transcription factors, resulting in changes in gene expression. These changes in gene expression are often cell typespecific and lead to cell growth, differentiation, or apoptosis, thereby regulating normal tissue structure and function. One key signal transduction pathway highly conserved in eukaryotes is the phosphatidylinositol 3-kinase (PI3K) 1 pathway (1), which is stimulated by a number of growth factors, including insulin and insulin-like growth factor 1 (1). Once a receptor tyrosine kinase has become activated by binding a specific ligand, it becomes autophosphorylated and binds PI3K heterodimers either directly, or indirectly via insulin receptor substrate (IRS) adaptor proteins (1-3). The interaction between the p85 regulatory subunit of PI3K and the receptor brings the catalytic domain (p110 subunit) of PI3K into contact with the plasma membrane, where it is able to phosphorylate its targets. Alternatively, PI3K can be juxtaposed to the plasma membrane via interactions with activated RAS family members. PI3K phosphorylates phosphatidylinositol (4,5)-diphosphate at the 3 position, resulting in the formatio...

During the menstrual cycle, the ovarian hormones oestradiol and progesterone control the ordered growth and differentiation of uterine cells. This remodelling process is critical for implantation of the developing embryo, the formation of the placenta, and maintenance of pregnancy. Failure of uterine tissues to respond appropriately to ovarian hormone signalling results in defective placentation, associated with a spectrum of pregnancy disorders such as recurrent miscarriages and preeclampsia. These obstetrical disorders are a major cause of maternal and perinatal morbidity and mortality. Progesterone exerts its action on target cells, at least in part, through binding to the progesterone receptor (PR), a member of the steroid/ thyroid hormone receptor superfamily of ligand-activated transcription factors. The mechanism by which progesterone controls the differentiation of human endometrial stromal cells, a process termed decidualization, in the secretory phase of the menstrual cycle is not well understood. Emerging evidence indicates that locally expressed factors and activation of the cAMP second messenger pathway integrate hormonal inputs and confer cellular specificity to progesterone action through the induction of diverse transcription factors capable of modulating PR function.