Dose-dependent insulin regulation of insulin-like growth factor binding protein-1 in human endometrial stromal cells is mediated by distinct signaling pathways

Recurrent Implantation Failure: Bioinformatic Discovery of Biomarkers and Identification of Metabolic Subtypes

Recurrent implantation failure (RIF) is a challenging scenario from different standpoints. This study aimed to investigate its correlation with the endometrial metabolic characteristics. Transcriptomics data of 70 RIF and 99 normal endometrium tissues were retrieved from the Gene Expression Omnibus database. Common differentially expressed metabolism-related genes were extracted and various enrichment analyses were applied. Then, RIF was classified using a consensus clustering approach. Three machine learning methods were employed for screening key genes, and they were validated through the RT-qPCR experiment in the endometrium of 10 RIF and 10 healthy individuals. Receiver operator characteristic (ROC) curves were generated and validated by 20 RIF and 20 healthy individuals from Peking University People's Hospital. We uncovered 109 RIF-related metabolic genes and proposed a novel two-subtype RIF classification according to their metabolic features. Eight characteristic genes (SRD5A1, POLR3E, PPA2, PAPSS1, PRUNE, CA12, PDE6D, and RBKS) were identified, and the area under curve (AUC) was 0.902 and the external validated AUC was 0.867. Higher immune cell infiltration levels were found in RIF patients and a metabolism-related regulatory network was constructed. Our work has explored the metabolic and immune characteristics of RIF, which paves a new road to future investigation of the related pathogenic mechanisms.

Insulin-like growth factor system components expressed at the conceptus-maternal interface during the establishment of equine pregnancy

In many species, the insulin-like growth factors (IGF1 and IGF2), their receptors and IGF binding proteins play important roles in preparing the endometrium for implantation, and regulating conceptus growth and development. To determine whether the IGF system may contribute to conceptus-maternal interaction during equine pre-implantation development, we evaluated mRNA expression for IGF system components in conceptuses, and endometrium recovered from pregnant and cycling mares, on days 7, 14, 21 and 28 after ovulation. We also investigated expression of IGF1, IGF2 and their receptors 6 and 11 days after transfer of day 8 embryos to synchronous (day 8) or asynchronous (day 3) recipient mares. Expression of IGF1 and IGF2, IGF1R, IGF2R, INSR and IGFBPs 1, 2, 4 and 5 was evident in endometrium and conceptus membranes during days 7–28. Endometrial IGF2, INSR, IGFBP1 and IGFBP2 expression increased between days 7 and 28 of pregnancy. In conceptus membranes, expression of all IGF system components increased with developmental stage. Immunohistochemistry revealed strong expression of IGF1, IGF2 and IGF1R in both endometrium and conceptus membranes, whereas INSR was highly expressed in endometrium but barely detectable in the conceptus. Finally, a negatively asynchronous uterine environment retarded IGF1, IGF2 and INSR expression in the conceptus, whereas in the endometrium only INSR expression was altered by asynchrony. The presence of IGFs, their receptors and IGFBPs in the endometrium and conceptus during early equine pregnancy, and down-regulation in the conceptus following asynchronous embryo transfer, suggest a role in conceptus-maternal communication during the preparation for implantation.

The Endometrial Transcriptome of Metabolic and Inflammatory Pathways During the Window of Implantation Is Deranged in Infertile Obese Polycystic Ovarian Syndrome Women

Introduction and Aim: Obese women with polycystic ovarian syndrome (PCOS) have a reduced rate of spontaneous conception even when their cycles are ovulatory. Endometrial receptivity is an important factor for poor implantation and increased miscarriage rates. Mechanisms in which both pathologies modify the endometrium are not fully clarified. The aim of our study was to compare the endometrial transcriptomic profiles between infertile obese PCOS (O-PCOS) women and infertile normal weight subjects during the window of implantation in ovulatory menstrual cycles. Methods: We conducted a prospective transcriptomic analysis of the endometrium using RNA sequencing. In this way, potential endometrial mechanisms leading to the poor reproductive outcome in O-PCOS patients could be characterized. Endometrial samples during days 21-23 of the menstrual cycle were collected from infertile O-PCOS women (n = 11) and normal weight controls (n = 10). Subgroups were defined according to the ovulatory/anovulatory status in the natural cycles, and O-PCOS women were grouped into the O-PCOS ovulatory (O-PCOS-ovul) subgroup. RNA isolation, sequencing with library reparation, and subsequent RNAseq data analysis were performed. Results: Infertile O-PCOS patients had 610 differentially expressed genes (DEGs), after adjustment for multiple comparisons with normal weight infertile controls, related to obesity (MXRA5 and ECM1), PCOS (ADAMTS19 and SLC18A2), and metabolism (VNN1 and PC). In the ovulatory subgroup, no DEGs were found, but significant differences in canonical pathways and the upstream regulator were revealed. According to functional and upstream analyses of ovulatory subgroup comparisons, the most important biological processes were related to inflammation (TNFR1 signaling), insulin signaling (insulin receptor signaling and PI3/AKT), fatty acid metabolism (stearate biosynthesis I and palmitate biosynthesis I), and lipotoxicity (unfolded protein response pathway). Conclusions: We demonstrated that endometrial transcription in ovulatory O-PCOS patients is deranged in comparison with the control ovulatory endometrium. The most important pathways of differentiation include metabolism and inflammation. These processes could also represent potential mechanisms for poor embryo implantation, which prevent the development of a successful pregnancy. ClinicalTrials.gov ID: NCT03353948.

Hyperandrogenism and Polycystic ovary syndrome: Effects in pregnancy and offspring development

Polycystic ovary syndrome (PCOS) is one of the major endocrine disorders affecting women of reproductive age. Its etiology remains unclear. It is suggested that environmental factors, and particularly the intrauterine environment, play key roles in PCOS development. Besides the role of androgens in PCOS pathogenesis, exposure to endocrine disruptors, as is Bisphenol A, could also contribute to its development. Although PCOS is considered one of the leading causes of ovarian infertility, many PCOS patients can get pregnant. Some of them by natural conception and others by assisted reproductive technique treatments. As hyperandrogenism (one of PCOS main features) affects ovarian and uterine functions, PCOS women, despite reaching pregnancy, could present high-risk pregnancies, including implantation failure, an increased risk of gestational diabetes, preeclampsia, and preterm birth. Moreover, hyperandrogenism may also be maintained in these women during pregnancy. Therefore, as an altered uterine milieu, including hormonal imbalance, could affect the developing organisms, monitoring these patients throughout pregnancy and their offspring development is highly relevant. The present review focuses on the impact of androgenism and PCOS on fertility issues and pregnancy-related outcomes and offspring development. The evidence suggests that the increased risk of pregnancy complications and adverse offspring outcomes of PCOS women would be due to the factors involved in the syndrome pathogenesis and the related co-morbidities. A better understanding of the involved mechanisms is still needed and could contribute to a better management of these women and their offspring. This article is categorized under: Reproductive System Diseases > Molecular and Cellular Physiology Reproductive System Diseases > Environmental Factors.

Interaction between insulin and androgen signalling in decidualization, cell migration and trophoblast invasion in vitro

Finely tuned decidualization of endometrial stromal fibroblasts into decidual cells is crucial for successful implantation and a healthy pregnancy. Both insulin and androgens are known to modulate decidualization, however, their complex effect on this process has not been fully elucidated. As hyperinsulinemia and hyperandrogenism are associated in clinical conditions, we aimed to investigate the interaction between insulin and androgens on decidualization. Primary human endometrial stromal cells were decidualized in vitro in the presence of insulin and/or androgens (dihydrotestosterone (DHT), testosterone). Gene or protein expressions of decidualization markers were measured, and cells size characteristics were determined. Migration of decidualizing endometrial stromal cells and invasion of HTR‐8/SVneo trophoblast spheroids were assessed. We found that insulin and androgens in combination enhanced the upregulation of several decidualization markers including prolactin, tissue factor, tissue inhibitor of matrix metalloproteinase 3 and connexin‐43, and also interacted in modulating cell size characteristics resulting in enlarged decidualizing cells. However, insulin and DHT together restricted the migration of decidualizing cells and invasion of trophoblast spheroids. Our findings suggest that insulin and androgens interact to potentiate the process of decidualization. On the other hand, inhibited cell migration and trophoblast invasion might negatively impact the function of decidualizing endometrial stromal cells.

Application of a Nomogram for Predicting the Risk of Subchorionic Hematoma in Early Pregnancy With In Vitro Fertilization-Embryo Transfer/Frozen Embryo Transfer

BACKGROUND

Subchorionic hematoma (SCH) is common in early pregnancy achieved by in vitro fertilization-embryo transfer/frozen embryo transfer (IVF-ET/FET), and is associated with adverse obstetric outcomes. However, there are no methods known to accurately predict the occurrence of SCH.

OBJECTIVE

To establish a nomogram prediction model for predicting the risk of SCH in early pregnancy with IVF-ET/FET and to analyze pregnancy outcomes of patients with SCH.

METHODS

Patients who underwent IVF-ET/FET treatment and were diagnosed with clinical pregnancy were enrolled in our study. A total of 256 patients with SCH were enrolled in the SCH group, and 526 patients without SCH in the control group. Logistic regression was used to screen risk factors for SCH, and the nomogram was developed according to the regression coefficient of relevant variables. Discrimination, effect, calibration, and the predictive model's clinical usefulness were assessed using the C-index, the area under the receiver operating characteristic standard curve, calibration plot, and decision curve analysis. Internal validation was assessed using bootstrapping validation. The effects of SCH on pregnancy outcomes were analyzed.

RESULTS

A multivariate logistic regression analysis showed that fresh embryo transfer, polycystic ovary syndrome, hydrosalpinx, and thin endometrium were risk factors affecting the occurrence of SCH. Based on the above factors, a predictive model for the risk of SCH was created. The model displayed good discrimination, with a C-index of 0.783 (95% confidence interval: 0.750-0.816), area under the receiver operating characteristic standard curve of 0.783, and good calibration. A high C-index value of 0.765 could still be reached in the interval validation. Decision curve analysis showed that the nomogram was clinically useful when the intervention was decided at the SCH possibility threshold of 4%-87%. For patients with successful deliveries, the occurrence of SCH did not influence the gestational weeks of delivery, mode of delivery, preterm birth, height, and weight of the newborn.

CONCLUSION

We screened the risk factors for SCH in patients who underwent IVF-ET/FET treatment. Successful establishment of a nomogram can effectively predict the occurrence of SCH. Furthermore, the incidence of miscarriage is higher in patients with SCH.

Insulin Signaling Via Progesterone-Regulated Insulin Receptor Substrate 2 is Critical for Human Uterine Decidualization

Decidualization, the process by which fibroblastic human endometrial stromal cells (HESC) differentiate into secretory decidual cells, is a critical event during the establishment of pregnancy. It is dependent on the steroid hormone progesterone acting through the nuclear progesterone receptor (PR). Previously, we identified insulin receptor substrate 2 (IRS2) as a factor that is directly regulated by PR during decidualization. IRS2 is an adaptor protein that functionally links receptor tyrosine kinases, such as insulin receptor (IR) and insulin-like growth factor 1 receptor (IGF1R), and their downstream effectors. IRS2 expression was induced in HESC during in vitro decidualization and siRNA-mediated downregulation of IRS2 transcripts resulted in attenuation of this process. Further use of siRNAs targeted to IR or IGF1R transcripts showed that downregulation of IR, but not IGF1R, led to impaired decidualization. Loss of IRS2 transcripts in HESC suppressed phosphorylation of both ERK1/2 and AKT, downstream effectors of insulin signaling, which mediate gene expression associated with decidualization and regulate glucose uptake. Indeed, downregulation of IRS2 resulted in reduced expression and membrane localization of the glucose transporters GLUT1 and GLUT4, resulting in lowered glucose uptake during stromal decidualization. Collectively, these data suggest that the PR-regulated expression of IRS2 is necessary for proper insulin signaling for controlling gene expression and glucose utilization, which critically support the decidualization process to facilitate pregnancy. This study provides new insight into the mechanisms by which steroid hormone signaling intersects with insulin signaling in the uterus during decidualization, which has important implications for pregnancy complications associated with insulin resistance and infertility.

Endometrial expression of receptivity markers subject to ovulation induction agents

PURPOSE

Implantation rates differ according to ovulation induction agents in ART. This study investigates the different local endometrial effects of LH- versus hCG-induced ovulation.

METHODS

Endometrial stromal cells from healthy patients were cultured with hCG or LH in different concentrations, supplemented with 250 ng/mL hCG and progesterone after 2 and 5 days. In addition after decidualization induction, cells were treated with hCG (50 or 250 ng/mL) or LH (10 or 50 ng/mL) for 3 days. Receptivity markers expression was evaluated by real-time quantitative PCR on day 3 and 6.

RESULTS

On day 3, non-decidualized cells treated with LH showed an increased expression of IGFBP1, IL-8 and CXCL12 compared to hCG. The expression pattern changed on day 6, where cells treated with hCG showed higher expression of implantation markers compared to LH-treated cells. Furthermore, on day 3, decidualized cells treated with hCG250 showed an increased IL8 and CXCL12 expression compared to LH10.

CONCLUSIONS

LH seems to modulate the local endometrial expression of receptivity markers earlier compared to hCG; however, the effect is not sustained over time in cells without prior decidualization. Though, in decidualized cells, pattern changed and an earlier positive effect of hCG was shown on IL-8 and CXCL12.

Effect of irisin on endometrial receptivity of rats with polycystic ovary syndrome

To investigate the influence of irisin on endometrial receptivity of rats with polycystic ovarian syndrome (PCOS). PCOS rats were randomly divided into PCOS group and irisin group, and normal rats were used as control group. The PCOS group and control group were injected intraperitoneally with normal saline while the irisin group with recombinant irisin. The serum and uterus were obtained. Detect serum sex hormones, including Testosterone (T), Estradiol (E₂), Progesterone (P), and glucose, insulin levels. Observe endometrial morphology by hematoxylin-eosin staining. Then evaluate the expression of leukemia inhibitory factor (LIF) and integrin αvβ3 in endometrium using ELISA, immunohistochemistry and Real-time PCR. (1) Levels of serum T, glucose and insulin in PCOS group were significantly higher than those in control and irisin group. (2) For the endometrial morphology, levels of equivalent diameter, area of uterine glands and gland cavity and endometrial average thickness were lower in PCOS group than those in control and irisin group. (3) LIF and integrin αvβ3 mRNA were basically consistent with protein expression. Levels of LIF and integrin αvβ3 were decreased in PCOS group when compared with control and irisin group. Irisin may improve endometrial receptivity by promoting expression of LIF and integrin αvβ3.

Metformin inhibits estradiol and progesterone-induced decidualization of endometrial stromal cells by regulating expression of progesterone receptor, cytokines and matrix metalloproteinases

BACKGROUND

Polycystic ovary syndrome (PCOS) is a serious threat for reproductive-aged women. Metformin has been used for the treatment of PCOS. However, its molecular mechanism in decidualization process of PCOS has not been well featured.

METHODS

RT-qPCR analysis was used to detect expression patterns of progesterone receptor (PGR), estradiol receptor alpha (ERα), Cytokeratin 8 and Vimentin in endometrial tissues of PCOS and non-PCOS patients. RT-qPCR assay was also employed to determine mRNA expression of prolactin, Insulin-like growth factor-binding protein 1 (IGFBP-1), matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP9). Cytokine secretion were measured by matching ELISA kits. Protein expression of p-ERK1/2, ERK1/2, p-p38 MAPK, p38 MAPK, and PGR (PGRA and PGRB) was tested by western blot assay.

RESULTS

PGR expression was upregulated in PCOS patients. Metformin alleviated estradiol (E2) and progesterone (P4) (EP)-induced decidualization of endometrial stromal cells. Abnormal cytokine secretion was observed in EP-stimulated endometrial stromal cells in the absence or presence of metfromin. Metformin suppressed EP-induced MMP-2 and MMP-9 upregulation. Metformin alleviated EP-triggered p38 MAPK inactivation and PGR (PGRA and PGRB) expression. Metfromin had no effect on ERK1/2 signaling in EP-stimulated endometrial stromal cells.

CONCLUSION

Metformin alleviated EP-induced decidualization of endometrial stromal cells by modulating secretion of multiple cytokines, inhibiting expression of MMP-2 and MMP-9, activating p38-MAPK signaling and reducing PGR expression, providing a deep insight into the molecular basis of metfromin therapy for PCOS patients.

VEGF may contribute to macrophage recruitment and M2 polarization in the decidua

It is increasingly evident that cytokines and growth factors produced in the decidua play a pivotal role in the regulation of the local immune microenvironment and the establishment of pregnancy. One of the major growth factors produced in the decidua is vascular endothelial growth factor (VEGF), which acts not only on endothelial cells, but also on multiple other cell types, including macrophages. We sought to determine whether decidua-derived VEGF affects macrophage recruitment and polarization using human endometrial/decidual tissue samples, primary human endometrial stromal cells (ESCs), and the human monocyte cell line THP1. In situ hybridization was used for assessment of local VEGF expression and immunohistochemistry was used for identification and localization of CD68-positive endometrial macrophages. Macrophage migration in culture was assessed using a transwell migration assay, and the various M1/M2 phenotypic markers and VEGF expression were assessed using quantitative real-time PCR (qRT-PCR). We found dramatic increases in both VEGF levels and macrophage numbers in the decidua during early pregnancy compared to the secretory phase endometrium (non-pregnant), with a significant increase in M2 macrophage markers, suggesting that M2 is the predominant macrophage phenotype in the decidua. However, decidual samples from preeclamptic pregnancies showed a significant shift in macrophage phenotype markers, with upregulation of M1 and downregulation of M2 markers. In THP1 cultures, VEGF treatment significantly enhanced macrophage migration and induced M1 macrophages to shift to an M2 phenotype. Moreover, treatment with conditioned media from decidualized ESCs induced changes in macrophage migration and polarization similar to that of VEGF treatment. These effects were abrogated by the addition of a potent VEGF inhibitor. Together these results suggest that decidual VEGF plays a significant role in macrophage recruitment and M2 polarization, and that inhibition of VEGF signaling may contribute to the shift in macrophage polarity observed in different pregnancy disorders, including preeclampsia.

Prokineticin 1 is up-regulated by insulin in decidualizing human endometrial stromal cells

Prokineticin 1 (PROK1), a hypoxia‐regulated angiogenic factor, has emerged as a crucial regulator of embryo implantation and placentation. Dysregulation of PROK1 has been linked to recurrent pregnancy loss, pre‐eclampsia, foetal growth restriction and preterm birth. These pregnancy complications are common in women with obesity and polycystic ovary syndrome, i.e. conditions associated with insulin resistance and compensatory hyperinsulinaemia. We investigated the effect of insulin on PROK1 expression during in vitro decidualization. Endometrial stromal cells were isolated from six healthy, regularly menstruating women and decidualized in vitro. Insulin induced a significant dose‐dependent up‐regulation of PROK1 on both mRNA and protein level in decidualizing endometrial stromal cells. This up‐regulation was mediated by hypoxia‐inducible factor 1‐alpha (HIF1α) via the phosphatidylinositol 3‐kinase (PI3K) pathway. Furthermore, we demonstrated that PROK1 did not affect the viability, but significantly inhibited the migration of endometrial stromal cells and the migratory and invasive capacity of trophoblast cell lines. This in vitro study provides new insights into the regulation of PROK1 by insulin in human decidualizing endometrial stromal cells, the action of PROK1 on migration of endometrial stromal cells, as well as migration and invasion of trophoblasts. We speculate that hyperinsulinaemia may be involved in the mechanisms by which PROK1 is linked to placenta‐related pregnancy complications.

Dysregulation of In Vitro Decidualization of Human Endometrial Stromal Cells by Insulin via Transcriptional Inhibition of Forkhead Box Protein O1

Insulin resistance and compensatory hyperinsulinemia are characteristic features of obesity and polycystic ovary syndrome, and both are associated with reduced fertility and implantation. There is little knowledge about the effect of insulin on the decidualization process and previous findings are contradictory. We investigated the effect of insulin on the regulation of forkhead box protein O1 (FOXO1), one of the most important transcription factors during decidualization. Endometrial stromal cells were isolated from six healthy, regularly menstruating women and decidualized in vitro. Gene expression levels of six putative FOXO1 target genes (including insulin-like growth factor binding protein-1 (IGFBP1) and prolactin (PRL)) were measured with Real-Time PCR following FOXO1 inhibition or insulin treatment. PI3K inhibition was used to identify the possible mechanism behind regulation. Subcellular localization of FOXO1 was analyzed with immunofluorescence. All the genes (IGFBP1, CTGF, INSR, DCN, LEFTY2), except prolactin, were evaluated as FOXO1 target genes in decidualizing stromal cells. Insulin caused a significant dose-dependent inhibition of the verified FOXO1 target genes. It was also demonstrated that insulin regulated FOXO1 target genes by transcriptional inactivation and nuclear export of FOXO1 via PI3K pathway. However, insulin did not inhibit the morphological transformation of endometrial stromal cells via transcriptional inactivation of FOXO1. This study provides new insights on the action of insulin on the endometrium via regulation of FOXO1. It is suggested that hyperinsulinemia results in dysregulation of a high number of FOXO1 controlled genes that may contribute to endometrial dysfunction and reproductive failure. Our findings may illuminate possible reasons for unexplained infertility.

Chronic endometritis and infertility

Chronic endometritis (CE) is a condition involving the breakdown of the peaceful co-existence between microorganisms and the host immune system in the endometrium. A majority of CE cases produce no noticeable signs or mild symptoms, and the prevalence rate of CE has been found to be approximately 10%. Gynecologists and pathologists often do not focus much clinical attention on CE due to the time-consuming microscopic examinations necessary to diagnose CE, its mild clinical manifestations, and the benign nature of the disease. However, the relationship between CE and infertility-related conditions such as repeated implantation failure and recurrent miscarriage has recently emerged as an area of inquiry. In this study, we reviewed the literature on the pathophysiology of CE and how it may be associated with infertility, as well as the literature regarding the diagnosis and treatment of CE. In addition, we discuss the value of hysteroscopic procedures in the diagnosis and treatment of CE.

IGF-1 and IGFBP-1 in peripheral blood and decidua of early miscarriages with euploid embryos: comparison between women with and without PCOS

This study aims to demonstrate the possible relationship between the insulin-like growth factor (IGF) system and early miscarriage in polycystic ovarian syndrome (PCOS) patients with euploid embryos. 40 pregnant women included. 9 had PCOS and miscarried; 20 had PCOS and a successful ongoing pregnancy; the remaining 11 women did not have PCOS and miscarried. An ultrasound scan was performed to prove clinical pregnancy and a blood sample was taken on day 55 ± 4 of gestation. Serum samples of IGF-1, insulin-like growth factor binding protein-1 (IGFBP-1), total testosterone, serum hormone binding protein (SHBG), leptin and soluble leptin receptor (sOb-R) were obtained. In miscarriages, samples of decidua were obtained during vaccum curettage. Embryonic chromosomes in all miscarriages were proven to be normal. The expression of IGF-1, IGFBP-1, leptin, long-form leptin receptor and androge sOb-R n receptor (AR) were examined in the decidua. We found that miscarried PCOS patients showed significantly increased free androgen index and free IGF index, as well as decreased SHBG and IGFBP-1 than other two groups in peripheral blood. In the decidua, miscarried PCOS patients showed significantly increased expression of IGF-1 and decreased IGFBP-1 when compared with non-PCOS. AR was not expressed in the decidua of either group. Our results suggest that early miscarriage is associated with increased IGF-1 and decreased IGFBP-1 in PCOS patients.

Metformin use and gynecological cancers: A novel treatment option emerging from drug repositioning

Metformin exerts antitumor effects mainly through AMP-activated protein kinase [AMPK] activation and phosphatidylinositol 3-kinase [PI3K]-Akt-mammalian target of rapamycin [mTOR] inhibition. This drug leads to activation of the cellular energy-sensing liver kinase B1 [LKB1]/AMPK pathway. LKB1 is implicated as a tumor suppressor gene in molecular pathogenesis of different malignancies. AMPK is a serine/threonine protein kinase that acts as an ultra-sensitive cellular energy sensor maintaining the energy balance within the cell. AMPK activation inhibits mRNA translation and proliferation in cancer cells via down-regulation of PI3K/Akt/mTOR pathway. Moreover, metformin decreases the production of insulin, insulin-like growth factor, inflammatory cytokines and vascular endothelial growth factor, and therefore it exerts anti-mitotic, anti-inflammatory and anti-angiogenetic effects. Recent in vitro and experimental data suggest that metformin electively targets cancer stem cells, and acts together with chemotherapy to block tumor growth in different cancers. Several epidemiological studies and meta-analysis have shown that metformin use is associated with decreased cancer risk and/or reduced cancer mortality for different malignancies. The present review analyzes the recent biological and clinical data suggesting a possible growth-static effect of metformin also in gynecological cancers. The large majority of available clinical data on the anti-cancer potential of metformin are based on observational studies. Therefore long-term phase II-III clinical trials are strongly warranted to further investigate metformin activity in gynecological cancers.

Branched-chain amino acids regulate insulin-like growth factor-binding protein 1 (IGFBP1) production by decidua and influence trophoblast migration through IGFBP1

STUDY QUESTION

Do branched-chain amino acids (BCAAs) influence the migration of human extravillous trophoblast (EVT) cells through changes in insulin-like growth factor-binding protein 1 (IGFBP1) production in decidual cells?

STUDY FINDING

Decidua-derived IGFBP1 had a stimulating effect on migration of EVT.

WHAT IS KNOWN ALREADY

IGFBP1 is abundantly secreted from human decidual cells and influences trophoblast migration in human placenta of early pregnancy. In hepatic cells, the expression of IGFBP1 is influenced by nutritional status and BCAAs regulate IGFBP1 production.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

This is a laboratory-based study using human decidual cells and trophoblast cells isolated from placental tissue of early pregnancy (n = 50) and grown as primary cultures. Production of IGFBP1 from decidual cells was examined by enzyme-linked immunosorbent assay and immunoblotting after incubation with or without BCAAs. EVT migration was evaluated using the media conditioned by decidual cells. The effect of conditioned media on phosphorylation of focal adhesion kinase (FAK) in EVT was also analyzed by immunoblotting. The same experiments were repeated in the presence of RGD peptide, which inhibits IGFBP1 binding to α5β1 integrin. An EVT migration assay and the immunoblotting of phosphorylated FAK were also conducted with exogenous IGFBP1. The effect of the conditioned media on cytotrophoblast cell number was also assessed using WST-1 in a cell proliferation assay.

MAIN RESULTS AND THE ROLE OF CHANCE

Deprivation of BCAAs on decidual cells significantly suppressed IGFBP1 secretion (P < 0.05, versus BCAA+). Exogenous IGFBP1-stimulated EVT migration (P < 0.05) and phosphorylation of FAK (P < 0.05), and the RGD peptide inhibited these effects. EVT migration and phosphorylation of FAK were stimulated by the conditioned media, presumably by IGFBP1 in the media. RGD treatment abrogated the stimulating effects of conditioned media. The conditioned media deprived of BCAAs had suppressive effects on EVT migration (P < 0.05, versus BCAA+) and phosphorylation of FAK (P < 0.05, versus BCAA+). The conditioned media did not affect number of cytotrophoblast cells.

LIMITATIONS, REASONS FOR CAUTION

The conclusions are based on in vitro experiments with human decidual cells and trophoblast cells isolated from placental tissue of early pregnancy, and we were unable to ascertain whether these mechanisms actually operate in vivo. We investigated the effect of decidua-derived IGFBP1 on EVT migration, however, we cannot completely rule out the possibility that endogenous IGF could also influence cell migration.

WIDER IMPLICATIONS OF FINDINGS

Interruption of the BCAA supply to uterine decidual cells in early pregnancy may suppress EVT migration through reduced IGFBP1 secretion, which may be one of the pathophysiological conditions responsible for pre-eclampsia.

LARGE SCALE DATA

None.

STUDY FUNDING/ AND COMPETING INTERESTS

All funds were obtained through Kyorin University School of Medicine. The authors have no conflict of interest to declare.

PCOS and cancer risk. Folia Histochem Cytobiol. 2009;47:S101-S105. [PMID: 20067879 DOI: 10.2478/v10042-009-0092-1]

Polycystic ovary syndrome (PCOS) affects approximately 5 to 10% of women of reproductive age. It is the most common reason of anovulation in infertile women. PCOS is accompanied by such conditions as oligo- or anovulation, hipertestosteronism, lower cell sensitivity to insulin, type II diabetes, hyperlipidemia and obesity. Each of the above-mentioned conditions is an approved risk factor proved to predispose towards cancer. However, PCOS is also a disease entity which differs in its clinical manifestation. For example not all patients suffer from obesity or hipertestosteronism related symptoms. From the analysis of literature it is possible to draw conclusions, that there is a possible correlation between PCOS and endometrial cancer, which emerges from clinical trials or research focused on molecular changes in endometrium patients with PCOS. On the other hand, correlation between PCOS and breast or ovary cancer is not so strong, in spite of single papers which are showing the link. The main problem in researching the correlation between PCOS and any cancer risk, is there is a very small group of women or the trial is imperfect (e.g. no control group). There is no meta-analysis focused on this correlation in literature. The change of criteria of PCOS in the past is also a big problem, because there was a number of definitions of PCOS, which results in inconsistent PCOS diagnoses over time. In this paper we would like to provide a description of studies that aimed at showing correlation between PCOS and cancer risk and underlying theoretical assumptions.

Polycystic ovary syndrome: Endometrial markers

Women with polycystic ovarian syndrome (PCOS) present with several endometrial abnormalities possibly explaining some of the adverse endometrium-related outcomes in these women. PCOS and an increased miscarriage rate have been suggested to coincide, but the results are conflicting. Recent studies have also shown increased risks of pregnancy-induced hypertension, preeclampsia, and premature delivery that may be related to altered decidualization/placentation in affected women. In the long run, PCOS per se is associated with the occurrence of endometrial cancer (EC), with obesity aggravating the risk. Most investigated markers of the endometrial abnormalities in women with PCOS are related to steroid hormone action (ERs (estrogen receptors), PRs (progesterone receptors), ARs (androgen receptors), and steroid receptor coactivators), endometrial receptivity/decidualization (HOXA10, αvβ3 integrin, and IGFBP-1 (insulin-like growth factor-binding protein 1)), glucose metabolism (IRs (insulin receptors), glucose transporters, IGFs) and inflammation/immune cell migration ((IL-6 (interleukin 6), CCL2 (CC motif ligand), and uNK (uterine natural killer) cells). Despite several endometrial abnormalities in women with PCOS, the clinical relevance of these findings still awaits future clarification; to date, no common screening protocols/recommendations for women with PCOS have been established.

Maternal whole grain intake and outcomes of in vitro fertilization

OBJECTIVE

To evaluate the relationship between pretreatment intake of whole grains and outcomes of IVF.

DESIGN

Prospective cohort study.

SETTING

Academic medical center.

PATIENT(S)

A total of 273 women who collectively underwent 438 IVF cycles.

INTERVENTION(S)

Whole grain intake was assessed with a validated food frequency questionnaire at enrollment.

MAIN OUTCOME MEASURE(S)

Intermediate and clinical end points of IVF were abstracted from medical records.

RESULT(S)

Women had a median whole grain intake of 34.2 g per day (∼1.2 servings/day). Higher pretreatment whole grain intake was associated with higher probability of implantation and live birth. The adjusted percentage of cycles resulting in live birth for women in the highest quartile of whole grain intake (>52.4 g/day) was 53% (95% confidence interval [CI] 41%, 65%) compared with 35% (95% CI 25%, 46%) for women in the lowest quartile (<21.4 g/day). This association was largely driven by intake of bran as opposed to germ. When intermediate end points of IVF were examined, only endometrial thickness on the day of ET was associated with whole grain intake. A 28-g per day (∼1 serving/day) increase in whole grain intake was associated with a 0.4-mm (95% CI 0.1, 0.7 mm) increase in endometrial thickness.

CONCLUSION(S)

Higher pretreatment whole grain intake was related to higher probability of live birth among women undergoing IVF. The higher probability of live birth may result from increased endometrial thickness on the day of ET and improved embryo receptivity manifested in a higher probability of implantation.

Roles of Oxidative Stress in Polycystic Ovary Syndrome and Cancers

Oxidative stress (OS) has received extensive attention in the last two decades, because of the discovery that abnormal oxidation status was related to patients with chronic diseases, such as diabetes, cardiovascular, polycystic ovary syndrome (PCOS), cancer, and neurological diseases. OS is considered as a potential inducing factor in the pathogenesis of PCOS, which is one of the most common complex endocrine disorders and a leading cause of female infertility, affecting 4%–12% of women in the world, as OS has close interactions with PCOS characteristics, just as insulin resistance (IR), hyperandrogenemia, and chronic inflammation. It has also been shown that DNA mutations and alterations induced by OS are involved in cancer pathogenesis, tumor cell survival, proliferation, invasion, angiogenesis, and so on. Furthermore, recent studies show that the females with PCOS are reported to have an increasing risk of cancers. As a result, the more serious OS in PCOS is regarded as an important potential incentive for the increasing risk of cancers, and this study aims to analyze the possibility and potential pathogenic mechanism of the above process, providing insightful thoughts and evidences for preventing cancer potentially caused by PCOS in clinic.

Insulin is an important risk factor of endometrial cancer among premenopausal women: a case-control study in China

The aim of the article was to evaluate the important role played by insulin in the development of endometrial cancer (EC) among Chinese premenopausal women. In this study, 128 endometrial cancer patients and 294 controls who were all premenopausal were included. Baseline characteristics data were collected and serum insulin, C-peptide, sex hormone-binding globulin, C-reaction protein, interleukin-6, and tumor necrosis factor-α levels were measured. Paired t test, χ(2) test, Spearman correlation coefficients, and univariate and multivariate logistic regression models were used in data analysis. Furthermore, insulin levels were categorized into quartiles, and likelihood ratio was calculated for the four categories. Blood insulin levels of the patients were significantly higher than those of the controls (P < 0.001). Factor analysis identified insulin (OR = 2.46; 95 % confidence interval (CI) = 1.55-3.91; P < 0.001) as the independent risk factor of EC. When insulin levels were categorized into quartiles, we found that insulin was positively associated with endometrial cancer risk [HR comparing extreme quartiles (HR q4-q1) = 4.44; 95 % CI = 2.59-7.62; P trend = 0.025]. After adjustment for body mass index (BMI) or waist-hip ratio (WHR), this association was attenuated, but still significant. In conclusion, insulin plays an important role in the carcinogenesis of EC among premenopausal women. Treatment targeting down-regulation of blood insulin levels seems effective in the prevention of this malignancy.

Polycystic ovary syndrome and risk of endometrial cancer: a mini-review

The polycystic ovary syndrome is the most common endocrinological disorder of reproductive age women with a prevalence of 5 to 8 %. The most common diagnostic criteria used for polycystic ovary syndrome are oligo- or an-ovulation, clinical and/ or biochemical signs of hyperandrogenism and polycystic ovaries. Hyperandrogenism results in increased estrogen levels and lack of cyclic progesterone due to anovulation and persistent stimulation of the endometrium may lead to endometrial hyperplasia or adenocarcinoma development. In this mini review, we aimed to evaluate the possible relationship between polycystic ovary syndrome and endometrial cancer.

Modulation of the IGF system and proliferation in human endometrial stromal cells by metformin: a dose-dependent effect

PURPOSE

To assess the metformin effect on endometrial stromal cell decidualization, proliferation, gene and protein expression of IGFBPs, IGFs and their receptors.

METHODS

Human endometrial stromal cells (hESCs) were cultured from endometrial biopsies of 11 women undergoing surgery for benign reasons. hESCs were decidualized with and without metformin in increasing doses. Supernatant and cells were harvested after decidualization for 12-14 days, followed by real-time PCR of IGFBP 1-6, IGF I, IGF II and their receptors. Prolactin, and IGFBP-1, -3, and -6 were additionally analyzed in supernatant by ELISA. Proliferation of hESCs and decidualization of hESCs were assessed under the influence of metformin. Data were analyzed using the paired t test with p < 0.05 considered significant.

RESULTS

While lower concentrations of metformin (10(-4), 10(-5 )M) did not influence the decidualization and proliferation capacity of hESCs, higher concentrations (10(-3), 10(-2 )M metformin) significantly (p < 0.05) diminished decidualization, as well as stromal cell proliferation in a dose-dependent manner. Higher concentrations of metformin lead to a significant (p < 0.05) dose-dependent attenuation of the progesterone effect with regard to IGFBP-1, -3, -5, -6, as well as IGF I receptor, while it did not change the expression of IGFBP-2 and -4, IGF I and II and the IGF II receptor. This was confirmed on the protein level for IGFBP-1, -3, and -6.

CONCLUSION

We were able to demonstrate for the first time a dose-dependent local effect of metformin within hESCs. Metformin might therefore influence locally the endometrial proliferation and maturation, and could open up new treatment options for gynecological diseases by vaginal application of metformin.

Obesity and PCOS: the effect of metabolic derangements on endometrial receptivity at the time of implantation

Successful embryonic implantation is the result of a receptive endometrium, a functional embryo at the blastocyst stage and a synchronized dialog between maternal and embryonic tissues. Successful implantation requires the endometrium to undergo steroid-dependent change during each menstrual cycle, exhibiting a short period of embryonic receptivity known as the window of implantation. The term "endometrial receptivity" was introduced to define the state of the endometrium during the window of implantation. It refers to the ability of the endometrium to undergo changes that will allow the blastocyst to attach, penetrate, and induce localized changes in the endometrial stroma. These changes are metabolically demanding, and glucose metabolism has been proven to be important for the preparation of the endometrium for embryo implantation. Obesity and polycystic ovary syndrome (PCOS) represent 2 common metabolic disorders that are associated with subfertility. The aim of this review is to summarize the effect of obesity and PCOS on endometrial receptivity at the time of implantation. Focus will be on metabolic alterations that regulate decidualization, including glucose metabolism, hyperinsulinemia, and hyperandrogenism.

Characterization of GAB1 expression over the menstrual cycle in women with and without polycystic ovarian syndrome provides a new insight into its pathophysiology

CONTEXT

In a previous microarray analysis, GRB2-associated binding protein 1 (GAB1), a docking protein closely related to the insulin receptor substrate, was down-regulated in endometrium of women with polycystic ovary syndrome (PCOS).

OBJECTIVE

The objective of the study was to characterize the cyclic expression of endometrial GAB1 in vivo in normal women and those with PCOS as well as investigate the possible mechanisms of endometrial regulation of GAB1 expression and action in vitro.

DESIGN

This was an experimental and case-control study.

SETTING

The study was conducted at a tertiary university hospital.

PATIENTS

Normal proven fertile women (controls; n = 31) and women with PCOS (cases; n = 26) participated in the study.

INTERVENTIONS

INTERVENTIONS included timed endometrial biopsies at different phases of the menstrual cycle. Ishikawa cells were cultured with β-estradiol (E2), medroxyprogesterone acetate, and E2 + medroxyprogesterone acetate. Transfection of small interfering RNA for GAB1 in Ishikawa cells incubated with or without insulin.

MAIN OUTCOME MEASURES

GAB1 mRNA expression in Ishikawa cells and in endometrium of cases and controls was measured. Protein expression of phosphorylated MAPK by Western blot was also measured. Immunohistochemical localization and expression of phosphorylated GAB1 in endometrium was also measured, using a digital histological score.

RESULTS

In endometrial tissue, GAB1 mRNA was reduced in the proliferative phase of PCOS women, compared with controls (P = .003; ANOVA). When all the phases of the menstrual cycle were grouped, GAB1 protein expression was reduced in endometrium of PCOS women (P < .0001; Student t test). E2 increases GAB1 mRNA expression in Ishikawa cells (P = .001; ANOVA). Phosphorylated MAPK is reduced in cells transfected with small interfering RNA for GAB1 (P = .008; ANOVA) and incubated with insulin.

CONCLUSIONS

GAB1 mRNA expression is positively modulated by E2. Endometrial GAB1 protein and mRNA expression are reduced in women with PCOS, suggesting that the endometrium of PCOS women have a defect in insulin signaling due to GAB1 down-regulation.

Influence of AKT on progesterone action in endometrial diseases

Progesterone plays an essential role in the maintenance of the endometrium; it prepares the endometrium for pregnancy, promotes decidualization, and inhibits estrogen-dependent proliferation. Progesterone function is often dysregulated in endometrial disease states. In addition, the PI3K/AKT signaling pathway is often overactive in endometrial pathologies and promotes the survival and proliferation of the diseased cells. Understanding how AKT influences progesterone action is critical in improving hormone-based therapies in endometrial pathologies. Here, we summarize recent studies investigating the crosstalk between the AKT pathway and progesterone receptor function in endometriosis and endometrial cancer.

Genome-wide analysis of histone modifications in human endometrial stromal cells

Dramatic changes of gene expressions occur in human endometrial stromal cells (ESCs) during decidualization. The changes in gene expression are associated with changes of chromatin structure, which are regulated by histone modifications. Here we investigated genome-wide changes in histone modifications associated with decidualization in human ESCs using chromatin immunoprecipitation combined with next-generation sequencing. ESCs were incubated with estradiol and medroxyprogesterone acetate for 14 days to induce decidualization. The chromatin immunoprecipitation-sequence data showed that induction of decidualization increased H3K27ac and H3K4me3 signals in many genomic regions but decreased in only a few regions. Most of the H3K27ac-increased regions (80%) and half of the H3K4me3-increased regions were located in the distal promoter regions (more than 3 kb upstream or downstream of the transcription start site). RNA sequence showed that induction of decidualization up-regulated 881 genes, 223 of which had H3K27ac- or H3K4me3-increased regions in the proximal and distal promoter regions. Induction of decidualization increased the mRNA levels of these genes more than it increased the mRNA levels of genes without H3K27ac- or H3K4me3-increased regions. Pathway analysis revealed that up-regulated genes with the H3K27ac- or H3K4me3-increased regions were associated with the insulin signaling, which may be involved in glucose uptake that is necessary for ESCs to undergo decidualization. These results show that histone modification statuses on a genome-wide basis change in human ESCs during decidualization. The main changes of histone modifications are increases of H3K27ac and H3K4me3 in both the proximal and distal promoter regions, which are involved in the up-regulation of gene expression that occurs during decidualization.

Insulin exerts direct effects on carcinogenic transformation of human endometrial organotypic cultures

Epidemiological studies suggest an association between elevated insulin levels and endometrial cancer. We studied the effects of insulin on normal endometrial cell proliferation with cytotoxicity assays. Organotypic cultures were used to determine the effects of insulin on the development of malignant histological features and anchorage independent growth. Western Blots were used to analyze the mitogen-activated protein kinases and AKT pathways. We found that insulin exerts direct effects on endometrial cells by increasing proliferation and promoting carcinogenesis. Our results suggest that this occurs through ERK 1/2 and glycogen synthase kinase-3β Ser9 phosphorylation.

Insulin-like growth factor I induces proliferation and migration of porcine trophectoderm cells through multiple cell signaling pathways, including protooncogenic protein kinase 1 and mitogen-activated protein kinase

During early pregnancy, the developing conceptus is dependent upon a wide range of growth factors and nutrients that are secreted by or transported by uterine epithelia into the uterus at the maternal-conceptus interface for successful implantation and placentation. Among these factors, insulin-like growth factor-I (IGF-I) is known to play an important role in development of the early embryo and uterine endometrium. However, few studies have been conducted with pigs to determine IGF-I-induced functional effects on peri-implantation embryos such as activation of cell signaling cascades responsible for growth, proliferation and differentiation of cells of the conceptus. Therefore, the aim of this study was to analyze mRNA expression of endometrial IGF-I and its receptor, to examine the functional role of IGF-I on primary porcine trophectoderm (pTr) cells and to assess potential signaling pathways responsible for biological activities of IGF-1. In the present study, expression of endometrial type I IGF receptor (IGF-IR) mRNA increased significantly from Day 10 to Day 12 of pregnancy and the increase was greater for pregnant than cyclic gilts. Both IGF-I and IGF-IR mRNAs were abundant in endometrial luminal-, glandular epithelia, and stratum compactum stroma on Day 12 of pregnancy. In addition, IGF-I significantly induced phosphorylation of AKT1, ERK1/2 and RPS6 in a time- and concentration-dependent manner in pTr cells. Immunofluorescence microscopy revealed that IGF-I treated pTr cells exhibited increased abundance of phosphorylated (p)-AKT1 and p-ERK1/2 MAPK proteins in the nucleus and cytoplasm, and p-RPS6 proteins in the cytosol as compared to non-treated pTr cells. In the presence of the ERK1/2 MAPK inhibitor (U0126), IGF-I-induced AKT1 phosphorylation was not affected, whereas the PI3K inhibitor (LY294002) decreased IGF-I-induced phosphorylation of ERK1/2 and AKT1 proteins, and both the PI3K-AKT1 and ERK1/2 MAPK pathways were blocked by LY294002. Furthermore, IGF-I significantly stimulated both proliferation and migration of pTr cells, but these effects were blocked by P38 inhibitor (SB203580), U0126, MTOR inhibitor (rapamycin) and LY294002. Taken together, these results indicate that IGF-I coordinately regulates multiple cell signaling pathways including PI3K-AKT1-RPS6 and ERK1/2 MAPK signaling pathways that are critical to proliferation, migration and survival of trophectoderm cells during early pregnancy in pigs.

Low expression of ERK signaling pathway affecting proliferation, cell cycle arrest and apoptosis of human gastric HGC-27 cells line

This study was carried out for the first time to examine the potential role and the underlying mechanisms of Lycopene in the gastric cancer HGC-27 cells. HGC-27 cells were seeded onto heat-sterilized coverslips in six-well plates and exposed to Lycopene (5, 10, 20, 30 and 40 μmol/L) for periods of 72 h at 37 °C. Results showed that Lycopene (5, 10, 20, 30 and 40 μmol/L) dose-dependently increased NBT positive rate and decreased lactate dehydrogenase activity in HGC-27 cells. In addition, Lycopene (5, 10, 20, 30 and 40 μmol/L) inhibited proliferation and induced G0-G1 phase cell cycle arrest in HGC-27 cells. Western blot and FQRT-PCR analysis showed that Lycopene decreased pERK and extracellular signal-regulated kinase (ERK) protein and mRNA expression in a dose-dependent manner. These findings demonstrate that Lycopene inhibited gastric cancer HGC-27 cells growth and stimulated its apoptosis via the suppressing ERK signaling pathway.

Does Metformin affect ER, PR, IGF-1R, β-catenin and PAX-2 expression in women with diabetes mellitus and endometrial cancer?

OBJECTIVE

Diabetes mellitus, as a risk factor for endometrial cancer (EC), causes an increase in insulin and IGF-1 concentrations in the blood serum. The increase in insulin and IGF-1 are considered mitogenic factors contributory to cancer development. Studies suggest that metformin has preventive activity, decreasing mortality and the risk of neoplasms. Since estrogen (ER), progesterone (PR) and IGF-1 (IGF-1R) receptor expression and β-catenin and PAX-2 mutations are significant in the development of endometrial cancer, it was decided to study these factors in patients with endometrial cancer and type 2 diabetes mellitus (DM2), and to establish the effects of metformin on their expression.

METHODS

The expression of ER, PR, IGF-1R, β-catenin and PAX-2 have been immunohistochemically investigated in 86 type I endometrial cancer specimens. Patients were grouped according to the presence of DM2 and the type of hypoglycemic treatment administered.

RESULTS

Comparing EC patients with DM2 and normal glycemic status, we found increased IGF-1R expression in women with DM2. A decrease in ER expression was noted in women with EC and DM2 receiving metformin as compared to women treated with insulin (p = 0.004). There was no statistically significant difference in PR, IGF-1R, β-catenin and PAX-2 expression among women receiving metformin and other hypoglycemic treatment.

CONCLUSION

Although epidemiological studies suggest the beneficial role of metformin in many human cancers, there are still few studies confirming its favorable effect on endometrial cancer. Decreased ER expression in patients receiving metformin needs further research to allow evaluation of its clinical significance.

Altered transcriptional regulation of cytokines, growth factors, and apoptotic proteins in the endometrium of infertile women with chronic endometritis

PROBLEM

Chronic endometritis (CE) is a poorly investigated and probably underestimated pathology, which may cause abnormal uterine bleeding (AUB), pain, and reproductive failures. Due to undefined symptoms and the normal presence of leukocytes in the endometrial mucosa, diagnosis may be missed. Fluid hysteroscopy is a reliable technique for diagnosing this pathology. Few data exist on the biochemical and paracrine alterations that occur in the endometrium of women diagnosed with CE. The aim of the study was to find molecular modification in endometrium related to CE.

METHOD OF STUDY

Sixteen women with hysteroscopic and histological diagnosis of CE and 10 healthy women as controls were enrolled. We compared the endometrial expression profile of 25 genes encoding proteins involved in the inflammatory response, proliferation, and apoptosis in endometrium during implantation window, using high-throughput real-time RT-PCR.

RESULTS

In women with CE, the endometrial expression of some genes was significantly altered. In particular, IGFBP1, BCL2, and BAX were up-regulated, while IL11, CCL4, IGF1, and CASP8 were down-regulated.

CONCLUSION

The altered gene endometrial expression may explain the impaired endometrial receptivity and the finding of endometrial hyperplastic lesions in women affected by CE.

Endometrial abnormality in women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy associated with infertility and metabolic disorder in women of reproductive age. Although the clinical and biochemical features are heterogeneous with individuals, the most widely accepted clinical characteristics of PCOS are oligo- or anovulation combined with hyperandrogenism. With the higher rate of implantation failure after induction of ovulation or higher risk of spontaneous miscarriage after pregnancy, the reduced fertility is apparently attributed not only to anovulation but also to endometrial dysfunction in patients with PCOS. Here we review the features of the endometrial abnormalities in women with PCOS. The ability to improve the endometrial functions is of potential therapeutic targets to increase reproductive outcome of women with PCOS.

Insulin promotes proliferation, survival, and invasion in endometrial carcinoma by activating the MEK/ERK pathway

The involvement of insulin in endometrial carcinoma (EC) was investigated using radioimmunoassay, Western blot, immunoprecipitation, MTT, and Annexin V-FITC/PI assays in tissue samples and cultured cells. Serum levels of insulin, p-p52Shc, p-p46Shc, Shc·Grb2 complexes, p-MEK, p-ERK, and cyclin D1 were elevated in patients with EC. Expression of key proteins in the MEK/ERK pathway, including p-p52Shc, Shc·Grb2 complexes, p-MEK, p-ERK, and cyclin D1, was significantly higher in patients with advanced FIGO stage, high grade, and lymph-node metastasis and correlated positively with serum insulin concentration. Insulin promotes Ishikawa 3-H-12 cell proliferation, survival, and invasion, and these effects induced by insulin were significantly blocked by MEK inhibitor PD98059. Insulin thus promotes EC cell proliferation, survival, and invasion via the MEK/ERK pathway.

Insulin resistance: a significant risk factor of endometrial cancer

OBJECTIVE

To review the role played by insulin resistance in the development of endometrial cancer.

METHODS

Relevant manuscripts and studies were searched on Medline using the terms endometrial cancer, insulin resistance, obesity, adipokine, C-peptide, leptin, adiponectin, plasminogen activator inhibitor-1, insulin, PI3K/Akt, Ras/MAPK and metformin alone or in combination.

RESULTS

Epidemiological studies have shown that insulin resistance is an important potential risk factor of endometrial cancer, and several research studies have been undertaken to determine the mechanism underlying its link to this malignant disease. Risk factors of insulin resistance, such as the inflammatory mediators, adipokines adiponectin, leptin and plasminogen activator inhibitor-1 and excessive androgen are also risk factors of endometrial cancer. High levels of insulin induced by insulin resistance have been found to exert direct and indirect effects that contribute to the development of endometrial cancer. Insulin directly promotes cell proliferation and survival through the PI3K/Akt and Ras/MAPK pathways. Moreover, the network among insulin, estrogen and insulin-like growth factor-1 also contributes to the development of endometrial cancer. Indirectly, insulin leads to changes in sex hormone levels, including increases in the levels of estrogen. Additionally, a small number of studies suggested that metformin, an insulin-sensitizing agent, has therapeutic potential for endometrial cancer.

CONCLUSIONS

This evidence suggests that insulin resistance plays a central role in endometrial cancer development. Understanding the relationship between insulin resistance and endometrial cancer may supply new ideas to fight this malignancy. Furthermore, combating insulin resistance may be a useful preventive and therapeutic strategy for endometrial cancer.

Metformin modulates IL-8, IL-1β, ICAM and IGFBP-1 expression in human endometrial stromal cells

To evaluate the effects of metformin on endometrial stromal cell gene expression and on the decidualization process, endometrial biopsies were collected from five healthy, regularly cycling women. Stromal cell culture was performed and decidualized with oestrogen/progesterone in the presence or absence of metformin and thereafter stimulated with insulin. The effect of metformin on decidualization was analysed by prolactin determination in the cell culture supernatant. Gene expression of insulin-like growth factor binding protein 1 (IGFBP-1), interleukin (IL) 8 and 1β and intercellular adhesion molecule (ICAM) was analysed by real-time PCR. Decidualization was significantly diminished in cells incubated with metformin (P<0.05) accompanied by a significant reduction of prolactin secretion in the supernatant (day 10: 2.2 fold, P<0.05; day 15: 3.1 fold, P<0.05). IGFBP-1 gene expression was reduced after long-term metformin exposure (7.7 fold, P<0.05). The negative effect of insulin on IL-8 (4.8 fold) and IL-1β (9.3 fold) gene expression was similarly found in cells incubated with metformin. As far as is known, this is the first demonstration of a change in endometrial gene and protein expression after in-vitro stimulation with metformin, including a diminished decidualization process and changes in genes relevant to implantation.

Does metformin influence the insulin-, IGF I- and IGF II-receptor gene expression and Akt phosphorylation in human decidualized endometrial stromal cells?

OBJECTIVE

To assess the effects of metformin on insulin-, IGF I-, and IGF II-receptor gene expression and Akt phosphorylation in decidualized human endometrial stromal cells (ESC) after stimulation with insulin, IGF I and II.

STUDY DESIGN

ESC were isolated from healthy, regularly cycling women and after two passages decidualized with estrogen/progesterone±metformin. Cells were incubated with insulin, IGF I or IGF II for 1, 5, and 10 min to assess Akt phosphorylation by Western blot. To investigate the insulin-, IGF I- and IGF II-receptor gene expression ESC were incubated with insulin, IGF I or IGF II for 6 and 24h.

RESULTS

Insulin- and IGF I-receptor gene expression in ESC changed significantly after incubation with insulin, IGF I or IGF II. This was further augmented in metformin pretreated cells, while IGF II-receptor gene expression changed particularly after pretreatment with metformin. Akt phosphorylation peaked after 5 min insulin, IGF I and IGF II stimulation in ESC in both control (control 0.08 ± 0.03 vs. insulin 0.74 ± 0.19, IGF I 0.68 ± 0.22, IGF II 0.53 ± 0.13, p<0.05) and metformin pretreated cells (control 0.03 ± 0.01 vs. insulin 0.75 ± 0.11, IGF I 0.74 ± 0.15, IGF II 0.67 ± 0.09, p<0.005). However, there was no significant difference between the control and metformin pretreated group.

CONCLUSION

Insulin, IGF I and IGF II lead to changes in their receptor gene expression and induced Akt phosphorylation in ESC. These effects were further highlighted in the presence of metformin.

Common genetic variation within IGFI, IGFII, IGFBP-1, and IGFBP-3 and endometrial cancer risk

OBJECTIVE

The insulin-like growth factor (IGF) pathway plays a critical role in the growth and development of the uterus and is believed to function as a mediator of steroid hormone actions in the endometrium. The local expression of genes encoding IGFs and IGF-binding proteins (IGFBPs) is important in determining IGF bioactivity in the uterus. Genetic variation in key genes within the IGF pathway may influence the rate of cellular proliferation and differentiation in the uterus and ultimately affect the risk of endometrial cancer. Our hypothesis is that variant alleles in key genes involved in the IGF pathway will influence the development of endometrial cancer.

METHODS

We conducted a case-control study nested within the Nurses' Health Study (NHS) and the Women's Health Study (WHS) to investigate the association between forty-four polymorphisms within IGFI, IGFII, IGFBP-1, and IGFBP-3 with endometrial cancer risk using 692 invasive endometrial cancer cases and 1723 matched controls. We used conditional logistic regression to calculate odds ratios (ORs) and 95% confidence intervals (CIs) to assess the risk of endometrial cancer.

RESULTS

We observed an inverse association with IGFII rs3741211 and endometrial cancer risk (OR=0.79 (95% CI: 0.63, 0.99)) and IGFII rs1004446 and endometrial cancer risk (OR=0.80 (95% CI: 0.68, 0.94)). We also observed an inverse association with IGFBP-3 rs2453839 and endometrial cancer risk (OR=0.81 (95%CI: 0.67, 0.98). However, we did not observe any statistically significant associations with the polymorphisms in IGFI and IGFBP1 and endometrial cancer risk.

CONCLUSIONS

Genetic variation with IGFII and IGFBP-3 may influence endometrial cancer risk in Caucasians. Polymorphisms in IGFI and IGFBP-1 were not associated with endometrial cancer risk, but further research is needed.

Polymerization of insulin-like growth factor-binding protein-1 (IGFBP-1) potentiates IGF-I actions in placenta

Insulin-like growth factor (IGF)-binding protein-1 (IGFBP-1), the main secretory protein of decidua that binds to IGFs and has been shown to inhibit or stimulate IGFs' bioactivities. Polymerization, one of the posttranslational modifications of IGFBP-1, has been shown to lead to loss of inhibiting effect of IGFBP-1 on IGF-I actions. The current studies were undertaken to elucidate the effects of steroid hormones on IGFBP-1 polymerization in trophoblast cell cultures. Placental tissues were obtained during legal, elective procedures of termination of pregnancy performed between 7 and 10 weeks of gestation, and primary trophoblast cells were separated. IGFBP-1 polymerization was analyzed by SDS-PAGE and immunoblotting. IGFBP-1 was polymerized when IGFBP-1 was added to trophoblast cell cultures. Polymerization of IGFBP-1 was inhibited by the addition of anti-tissue transglutaminase antibody into the culture media. There was an increase in the intensity of polymerized IGFBP-1 bands with the addition of medroxyprogesterone acetate (MPA), while no such difference was observed upon treatment with estradiol. MPA also increased the expression of tissue transglutaminase on trophoblast cell membranes. IGF-I stimulated trophoblast cell migration, while IGFBP-1 inhibited this IGF-I-induced trophoblast response. Addition of MPA attenuated the inhibitory effects of IGFBP-1 on IGF-I-induced trophoblast cell migration. IGFBP-1 was polymerized by tissue transglutaminase on the cell surface of trophoblasts, and MPA increased tissue transglutaminase expression on the cell surface and facilitated IGFBP-1 polymerization. These results suggest that progesterone might facilitate polymerization of decidua-secreted IGFBP-1 and increase IGF-I actions at feto-maternal interface, thereby stimulating trophoblast invasion of maternal uterus.

Decidual PTEN expression is required for trophoblast invasion in the mouse

Trophoblast invasion likely depends on complex cross talk between the fetal and maternal tissues and may involve the modulation of phosphatidylinositol 3-kinase (PI3K)/AKT signaling activity in maternal decidual cells. In this report, we studied implantation in Pten(tm1Hwu/tm1Hwu);Amhr2(tm3(cre)Bhr/+) mice, which lack the PI3K signaling antagonist gene Pten in myometrial and stromal/decidual cells. Primiparous Pten(tm1Hwu/tm1Hwu);Amhr2(tm3(cre)Bhr/+) mice were found to be subfertile because of increased fetal mortality at e11.5. Histopathological analyses revealed a failure of decidual regression in these mice, accompanied by reduced or absent invasion of fetal trophoblast glycogen cells and giant cells, abnormal development of the placental labyrinth, and frequent apparent intrauterine fetal growth restriction. Unexpectedly, the loss of phosphate and tensin homolog deleted on chromosome 10 (PTEN) expression in Pten(tm1Hwu/tm1Hwu);Amhr2(tm3(cre)Bhr/+) decidual cells was not accompanied by a detectable increase in AKT phosphorylation or altered expression or activation of PI3K/AKT downstream effectors such as mammalian target of rapamycin or glycogen synthase kinase-3β. Terminal deoxynucleotidyl transferase-mediated nick end labeling and bromodeoxyuridine incorporation analyses attributed to the lack of decidual regression mainly to decreased apoptosis in Pten(tm1Hwu/tm1Hwu);Amhr2(tm3(cre)Bhr/+) decidual cells, rather than to increased proliferation. Remodeling of the maternal vasculature was delayed in Pten(tm1Hwu/tm1Hwu);Amhr2(tm3(cre)Bhr/+) uteri at e11.5, as evidenced by persistence of vascular smooth muscle and decreased infiltration of uterine natural killer cells. In addition, thickening of the myometrium and disorganization of the muscle fibers were observed before and throughout gestation. Almost all Pten(tm1Hwu/tm1Hwu);Amhr2(tm3(cre)Bhr/+) mice failed to carry a second litter to term, apparently attributable to endometrial hyperplasia and uterine infections. Together, these data demonstrate novel roles of PTEN in the mammalian uterus and its requirement for proper trophoblast invasion and decidual regression.

Endometrial thickness, uterine, and ovarian ultrasonographic features in adolescents with polycystic ovarian syndrome

OBJECTIVE

Our aim was to evaluate uterine and ovarian ultrasonographic features including endometrial thickness (ET) in adolescent females with PCOS, which is limited in this population.

METHODS

We performed a retrospective chart review of young females (n=51) ranging in age from 10 to 18 years with the diagnosis of PCOS. Clinical, biochemical and pelvic sonography data were reviewed. Sonographic data included uterine parameters of ET, length, and volume as well as ovarian volume and follicular morphologic features.

RESULTS

Data in 51 girls were analyzed. Menstrual periods were reported as irregular in 26/51 (50.9%), amenorrheic in 19/51 (37.2%), regular in 4/51 (7.8%) and metrorrhagia in 2/51 (3.9%). Uterine features revealed that the endometrial stripe was enlarged (>7mm) in 16/51 (31.4%) of girls, all with homogeneous appearance. The uterine length was lower than normal in 22/51 (43.1%) of girls, normal in 21/51 (41.2%), and higher than normal in 8/51 (15.7%). Uterine volume was normal in 31/51 (60.7%) and higher in 20/51 (39.3%) of girls. Enlarged ovarian volume was found in 22/51 (43%) of patients. Mean ovarian volumes were 16.1cm(3) and 13.1cm(3) in bilateral and unilaterally enlarged ovaries, respectively. The morphology of ovarian follicles was studied in a subset of 40 patients. The location of ovarian follicles was peripheral in 81% and mixed in 19%. The number of follicles was also examined in 43 patients. They were few (<5) in 12%, moderate (5-10) in 5% and multiple (>10) in 84% cases. There was the presence of at least one >10mm cyst in 25% of girls.

CONCLUSION

Majority of the adolescents with PCOS demonstrated multiple peripheral ovarian follicles, with large ovarian volumes in some, indicating an important role of ultrasonography in the diagnosis of PCOS, even at a younger age. Endometrial thickness, uterine length, ovarian size, and follicular morphology should be carefully examined in cases of adolescent PCOS.

Increased mitogen-activated protein kinase kinase/extracellularly regulated kinase activity in human endometrial stromal fibroblasts of women with endometriosis reduces 3',5'-cyclic adenosine 5'-monophosphate inhibition of cyclin D1

Endometriosis is characterized by endometrial tissue growth outside the uterus, due primarily to survival, proliferation, and neoangiogenesis of eutopic endometrial cells and fragments refluxed into the peritoneal cavity during menses. Although various signaling molecules, including cAMP, regulate endometrial proliferation, survival, and embryonic receptivity in endometrium of women without endometriosis, the exact molecular signaling pathways in endometrium of women with disease remain unclear. Given the persistence of a proliferative profile and differential expression of genes associated with the MAPK signaling cascade in early secretory endometrium of women with endometriosis, we hypothesized that ERK1/2 activity influences cAMP regulation of the cell cycle. Here, we demonstrate that 8-Br-cAMP inhibits bromodeoxyuridine incorporation and cyclin D1 (CCND1) expression in cultured human endometrial stromal fibroblasts (hESF) from women without but not with endometriosis. Incubation with serum-containing or serum-free medium resulted in higher phospho-ERK1/2 levels in hESF of women with vs. without disease, independent of 8-Br-cAMP treatment. The MAPK kinase-1/2 inhibitor, U0126, fully restored cAMP down-regulation of CCND1, but not cAMP up-regulation of IGFBP1, in hESF of women with vs. without endometriosis. Immunohistochemistry demonstrated the highest phospho-ERK1/2 in the late-secretory epithelial and stromal cells in women without disease, in contrast to intense immunostaining in early-secretory epithelial and stromal cells in those with disease. These findings suggest that increased activation of ERK1/2 in endometrial cells from women with endometriosis may be responsible for persistent proliferative changes in secretory-phase endometrium.

VEGF blockade inhibits angiogenesis and reepithelialization of endometrium

Despite extensive literature on vascular endothelial growth factor (VEGF) expression and regulation by steroid hormones, the lack of clear understanding of the mechanisms of angiogenesis in the endometrium is a major limitation for use of antiangiogenic therapy targeting endometrial vessels. In the current work, we used the rhesus macaque as a primate model and the decidualized mouse uterus as a murine model to examine angiogenesis during endometrial breakdown and regeneration. We found that blockade of VEGF action with VEGF Trap, a potent VEGF blocker, completely inhibited neovascularization during endometrial regeneration in both models but had no marked effect on preexisting or newly formed vessels, suggesting that VEGF is essential for neoangiogenesis but not survival of mature vessels in this vascular bed. Blockade of VEGF also blocked reepithelialization in both the postmenstrual endometrium and the mouse uterus after decidual breakdown, evidence that VEGF has pleiotropic effects in the endometrium. In vitro studies with a scratch wound assay showed that the migration of luminal epithelial cells during repair involved signaling through VEGF receptor 2-neuropilin 1 (VEGFR2-NP1) receptors on endometrial stromal cells. The leading front of tissue growth during endometrial repair was strongly hypoxic, and this hypoxia was the local stimulus for VEGF expression and angiogenesis in this tissue. In summary, we provide novel experimental data indicating that VEGF is essential for endometrial neoangiogenesis during postmenstrual/postpartum repair.