Clinical changes of leptin/ghrelin and PAI-1 levels in adolescent girls with abnormal uterine bleeding-ovulatory dysfunction

OBJECTIVE

To observe and compare the expression of energy regulators (leptin/ghrelin) and PAI-1 in girls with abnormal uterine bleeding-ovulatory dysfunction (AUB-O) and healthy adolescent girls.

METHODS

A total of 80 adolescent girls were studied including 60 with AUB-O and 20 healthy girls. All the general characteristics of subjects including height, weight, age, and age at menarche were collected after consent. The concentration of plasma leptin, ghrelin, PAI-1, and sex hormones was examined using enzyme-linked immunosorbent assay (ELISA) and DXI800 Access immunoassay system respectively.

RESULTS

Two groups were comparable in the age at menarche, visiting age, postmenarchal years, and BMI SDS (p > .05). Levels of leptin (11.12 ± 4.96 ng/ml vs. 18.59 ± 13.22 ng/ml, p < .001) and PAI-1 (116.40 ± 36.63 ng/ml vs. 173.19 ± 52.44 ng/ml, p < .001) in girls with AUB-O were significantly lower than that in healthy girls, and the levels of ghrelin were significantly higher than that in healthy girls (1.52 ± 4.20 ng/ml vs. 0.43 ± 0.64 ng/ml, p = .01). At the same time, we also found that girls with AUB-O showed negative correlation between the level of leptin, ghrelin, and estradiol.

CONCLUSIONS

Energy metabolism and coagulation might play a role in the development of AUB-O in adolescent girls.

Cyclic decidualization of the human endometrium in reproductive health and failure

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.

Mechanisms of normal and abnormal endometrial bleeding

Expression of tissue factor (TF), the primary initiator of coagulation, is enhanced in decidualized human endometrial stromal cells (HESC) during the progesterone-dominated luteal phase. Progesterone also augments a second HESC hemostatic factor, plasminogen activator inhibitor-1 (PAI-1). In contrast, progestins inhibit HESC matrix metalloproteinase (MMP)-1, 3 and 9 expression to stabilize endometrial stromal and vascular extracellular matrix. Through these mechanisms decidualized endometrium is rendered both hemostatic and resistant to excess trophoblast invasion in the mid-luteal phase and throughout gestation to prevent hemorrhage and accreta. In non-fertile cycles, progesterone withdrawal results in decreased HESC TF and PAI-expression and increased MMP activity and inflammatory cytokine production promoting the controlled hemorrhage of menstruation and related tissue sloughing. In contrast to these well ordered biochemical processes, unpredictable endometrial bleeding associated with anovulation reflects absence of progestational effects on TF, PAI-1 and MMP activity as well as unrestrained angiogenesis rendering the endometrium non-hemostatic, proteolytic and highly vascular. Abnormal bleeding associated with long-term progestin-only contraceptives results not from impaired hemostasis but from unrestrained angiogenesis leading to large fragile endometrial vessels. This abnormal angiogenesis reflects progestational inhibition of endometrial blood flow promoting local hypoxia and generation of reactive oxygen species that increase production of angiogenic factors such as vascular endothelial growth factor (VEGF) in HESCs and Angiopoietin-2 (Ang-2) in endometrial endothelial cells while decreasing HESC expression of angiostatic, Ang-1. The resulting vessel fragility promotes bleeding. Aberrant angiogenesis also underlies abnormal bleeding associated with myomas and endometrial polyps however there are gaps in our understanding of this pathology.

Minireview: modulation of hormone receptor signaling by dietary anticancer indoles

Indole-3-carbinol and its diindole condensation product 3-3'-diindolylmethane are dietary phytochemicals that have striking anticarcinogenic properties in human cancer cells. Molecular, cellular, physiological, and clinical studies have documented that both indole-3-carbinol and 3-3'-diindolylmethane have potent endocrine modulating activities through a myriad of mechanisms. The focus of this review is to discuss the evidence that directly links the anticancer actions of these two indole compounds to the control of steroid receptor and growth factor receptor signaling.

Pregnancy-associated changes in the hemostatic system

Pregnancy, from implantation to parturition, presents unique and profound challenges to a women's hemostatic system. During pregnancy, potentially catastrophic bleeding can occur during implantation and endovascular trophoblast invasion of the maternal spiral arteries. The risk of hemorrhage reaches a peak during the third stage of labor when the placenta is shorn from the decidua basalis exposing 120 spiral arteries largely denuded of their smooth muscle, and thus, their ability to constrict in response to injury. These challenges are met by dramatic changes in the local uterine, and systemic hemostatic systems. The net effect of these changes is to increase the efficiency of clotting and to impair fibrinolysis. Unfortunately, they also lead to an increase in the prevalence of venous thromboembolism, which is otherwise uncommon in reproductive age women.

Progesterone receptor isoforms A and B differentially regulate MUC1 expression in uterine epithelial cells

MUC1 expression responds differently to changes in progesterone (P) levels in mouse vs. human uterine epithelium. Two isoforms of progesterone receptor, PRA and PRB, mediate the physiological effects of P. Using transient transfection of a human uterine epithelial cell line, HEC-1A, we showed that liganded PRB stimulated MUC1 gene activity. PRA alone had little effect on MUC1 promoter activity, but antagonized the PRB-mediated stimulation. The region from 523 to 570 bp upstream of the transcriptional start site was shown to be required for the P response. Mutation of two potential P-responsive element (PRE) half-sites in this region partially inhibited the PRB-mediated response, and one PRE half-site disrupted binding of both PRB and PRA to a consensus PRE in an EMSA. These along with other studies indicated that multiple cis elements in the -523- to -570-bp region cooperate to mediate P responsiveness, and that PR interaction with other transcription factors in this region is likely. Using ovariectomized wild-type, PR knockout (PRKO), PRAKO, and PRBKO mice, P antagonism of estrogen-stimulated Muc1 protein and mRNA expression was shown to be dependent on PRA. In summary, these data show that liganded PRB stimulates MUC1 expression in human uterine epithelial cells, whereas liganded PRA antagonizes MUC1 expression in both human and mouse uterine epithelial cells. The differential MUC1 response to P in these two species may be due to dissimilar expression of the two PR isoforms in the uterine epithelium.

Sp1 and Sp3 regulate the basal transcription of receptor activator of nuclear factor kappa B ligand gene in osteoblasts and bone marrow stromal cells

Receptor activator of nuclear factor kappa B ligand (RANKL), a potent regulator of osteoclast formation and function, is expressed by osteoblasts and bone marrow stromal cells. However, the molecular mechanism underlying RANKL expression in osteoblast/stromal cells remains largely unclear. Here, we characterized the molecular mechanism controlling RANKL basal transcription in osteoblast/stromal cells. We cloned a 1,103-bp murine RANKL promoter (from -953 to +150, relative to the transcription start site). Using a series of deletion mutants of the 1,103-bp promoter, we identified a 100-bp region (-154 to -54) mediating RANKL basal transcription in both osteoblasts and bone marrow stromal cells. Electrophoretic mobility shift assay (EMSA) using five overlapping oligonucleotides (Probes 1-5) spanning the 100-bp region showed that Probes 1 and 2 specifically bound nuclear proteins with high affinity from both cell types. Computer analysis revealed that Probes 1 and 2 contain a putative Sp1-binding site. Supershift assays with Sp1 and Sp3 antibodies confirmed that the nuclear proteins binding to Probes 1 and 2 are Sp1 and Sp3. Functionally, the mutation of the Sp1/Sp3 site in Probe 1 profoundly reduced the basal promoter activity while the mutation of the one in Probe 2 resulted in moderate reduction in the basal promoter activity. Moreover, the mutation of both sites abrogated the RANKL basal promoter activity, indicating that Sp1 and Sp3 play a key role in the RANKL basal transcription in osteoblasts and bone marrow stromal cells.

An Sp1-NF-Y/progesterone receptor DNA binding-dependent mechanism regulates progesterone-induced transcriptional activation of the rabbit RUSH/SMARCA3 gene

Steroids regulate alternative splicing of rabbit RUSH/SMARCA3, an SWI/SNF-related transcription factor. Transactivation was evaluated in 2057 bp of genomic sequence. Truncation analysis identified a minimal 252-bp region with strong basal promoter activity in transient transfection assays. The size of the 5'-untranslated region (233 bp) and the transcription start site were determined by primer extension analysis. The transcription start site mapped to a consensus initiator (Inr) element in a TATA-less region with a downstream promoter element (+29). These elements were authenticated by mutation/deletion analysis. The Inr/downstream promoter element combination is conserved in the putative core promoter (-35/+35) of the human ortholog, suggesting that transcription initiation is similarly conserved. Two Sp1 sites that are also conserved in the putative promoter of human SMARCA3 and a RUSH binding site (-616/-611) that is unique to the rabbit promoter repress basal transcription. These sites were variously authenticated by gel shift and chromatin immunoprecipitation assays. Analysis of the proximal promoter showed the -162/+90 region was required for progesterone responsiveness in transient transfection assays. Subsequent mutation/deletion analysis revealed a progesterone receptor half-site mediated induction by progesterone. An overlapping Y-box (in the reverse ATTGG orientation) repressed basal transcription and progesterone-induced transcriptional activation in the presence of the Sp1 sites. The specificity of progesterone receptor and transcription factor NF-Y binding were authenticated by gel shift assays. Chromatin immunoprecipitation assays confirmed the Y-box effects were mediated in a DNA binding-dependent fashion. This represents a unique regulatory scenario in which ligand-dependent transactivation by the progesterone receptor is subject to Sp1/NF-Y repression.