The IGF system in in-vitro human decidualization

The Long Non-Coding RNA Gene AC027288.3 Plays a Role in Human Endometrial Stromal Fibroblast Decidualization

During the secretory phase of the menstrual cycle, endometrial fibroblast cells begin to change into large epithelial-like cells called decidual cells in a process called decidualization. This differentiation continues more broadly in the endometrium and forms the decidual tissue during early pregnancy. The cells undergoing decidualization as well as the resulting decidual cells, support successful implantation and placentation during early pregnancy. This study was carried out to identify new potentially important long non-coding RNA (lncRNA) genes that may play a role in human endometrial stromal fibroblast cells (hESF) undergoing decidualization in vitro, and several were found. The expression of nine was further characterized. One of these, AC027288.3, showed a dramatic increase in the expression of hESF cells undergoing decidualization. When AC027288.3 expression was targeted, the ability of the cells to undergo decidualization as determined by the expression of decidualization marker protein-coding genes was significantly altered. The most affected markers of decidualization whose expression was significantly reduced were FOXO1, FZD4, and INHBA. Therefore, AC027288.3 may be a major upstream regulator of the WNT-FOXO1 pathway and activin-SMAD3 pathways previously shown as critical for hESF decidualization. Finally, we explored possible regulators of AC027288.3 expression during human ESF decidualization. Expression was regulated by cAMP and progesterone. Our results suggest that AC027288.3 plays a role in hESF decidualization and identifies several other lncRNA genes that may also play a role.

Expression of vascular endothelial growth factor A (VEGFA), placental growth factor (PlGF) and insulin-like growth factor 1 (IGF-1) in serum from women undergoing frozen embryo transfer

VEGFA, PlGF and IGF-1 are three main angiogenic factors which play significant roles in embryo implantation. However, the relationship between serum expressions of VEGFA, PlGF and IGF-1 and pregnancy outcomes has not been fully illustrated. In this study, serum specimens were collected precisely on day 7 after the LH surge in a natural non-conception cycle from 38 infertile patients who underwent frozen embryo transfer (FET) treatment. ELISA was used to determine the concentrations of VEGFA, PlGF and IGF-1. Serum levels of VEGFA, PlGF and IGF-1 were compared between patients who conceived (n=25) and who did not (n=13). Correlation and linear regression analyses were used to investigate the correlations of serum angiogenic factors and β-hCG MoM levels in the pregnant group. The results demonstrated that no significant difference was found in serum VEGFA, PlGF or IGF-1 concentration between pregnant and non-pregnant women. Spearman correlation analysis revealed a positive correlation between IGF-1 concentration and β-hCG level in pregnant participants (rs = 0.490, p = 0.013). In conclusion, serum IGF-1 level correlated positively with β-hCG level in pregnant women, which may provide information on the prognostic value of IGF-1 in this group of women.

ATOH8 Expression Is Regulated by BMP2 and Plays a Key Role in Human Endometrial Stromal Cell Decidualization

During the secretory phase of the menstrual cycle, elongated fibroblast-like mesenchymal cells in the uterine endometrium begin to transdifferentiate into polygonal epithelioid-like (decidual) cells. This decidualization process continues more broadly during early pregnancy, and the resulting decidual tissue supports successful embryo implantation and placental development. This study was carried out to determine if atonal basic helix-loop-helix transcription factor 8 (ATOH8) plays a role in human endometrial stromal fibroblast (ESF) decidualization. ATOH8 messenger RNA and protein expression levels significantly increased in human ESF cells undergoing in vitro decidualization, with the protein primarily localized to the nucleus. When ATOH8 expression was silenced, the ability of the cells to undergo decidualization was significantly diminished. Overexpression of ATOH8 enhanced the expression of many decidualization markers. Silencing the expression of ATOH8 reduced the expression of FZD4, FOXO1, and several known FOXO1-downstream targets during human ESF cell decidualization. Therefore, ATOH8 may be a major upstream regulator of the WNT/FZD-FOXO1 pathway, previously shown to be critical for human endometrial decidualization. Finally, we explored possible regulators of ATOH8 expression during human ESF decidualization. BMP2 significantly enhanced ATOH8 expression when cells were stimulated to undergo decidualization, while an ALK2/3 inhibitor reduced ATOH8 expression. Finally, although the steroids progesterone plus estradiol did not affect ATOH8 expression, the addition of cyclic adenosine monophosphate (cAMP) analogue alone represented the major effect of ATOH8 expression when cells were stimulated to undergo decidualization. Our results suggest that ATOH8 plays a crucial role in human ESF decidualization and that BMP2 plus cAMP are major regulators of ATOH8 expression.

The single-cell atlas of cultured human endometrial stromal cells

OBJECTIVE

To systematically analyze the cell composition and transcriptome of primary human endometrial stromal cells (HESCs) and transformed human endometrial stromal cells (THESCs).

DESIGN

The primary HESCs from 3 different donors and 1 immortalized THESC were collected from the human endometrium at the midsecretory phase and cultured in vitro.

SETTING

Academic research laboratory.

PATIENT(S)

None.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Single-cell ribonucleic acid sequencing analysis.

RESULT(S)

We found the individual differences among the primary HESCs and bigger changes between the primary HESCs and THESCs. Cell clustering with or without integration identified cell clusters belonging to mature, proliferative, and active fibroblasts that were conserved across all samples at different stages of the cell cycles with intensive cell communication signals. All primary HESCs and THESCs can be correlated with some subpopulations of fibroblasts in the human endometrium.

CONCLUSION(S)

Our study indicated that the primary HESCs and THESCs displayed conserved cell characters and distinct cell clusters. Mature, proliferative, and active fibroblasts at different stages or cell cycles were detected across all samples and presented with a complex cell communication network. The cultured HESCs and THESCs retained the features of some subpopulations within the human endometrium.

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.

Calpain7 negatively regulates human endometrial stromal cell decidualization in EMs by promoting FoxO1 nuclear exclusion via hydrolyzing AKT1

Endometrial receptivity damage caused by impaired decidualization may be one of the mechanisms of infertility in endometriosis (EMs). Our previous study demonstrated that Calpain-7 (CAPN7) is abnormally overexpressed in EMs. Whether CAPN7 affects the regulation of decidualization and by what mechanism CAPN7 regulates decidualization remains to be determined. In this study, we found CAPN7 expression decreased during human endometrial stromal cell (HESC) decidualization in vitro. CAPN7 negatively regulated decidualization in vitro and in vivo. We also identified one conserved potential PEST sequence in the AKT1 protein and found that CAPN7 was able to hydrolyse AKT1 and enhance AKT1's phosphorylation. Correspondingly, CAPN7 notably promoted the phosphorylation of Forkhead Box O1 (FoxO1), the downstream of AKT1 protein, at Ser319, leading to increased FoxO1 exclusion from nuclei and attenuated FoxO1 transcriptional activity in decidualized HESC. In addition, we detected endometrium CAPN7, p-AKT1 and p-FoxO1 expressions were increased in EMs. These data demonstrate that CAPN7 negatively regulates HESC decidualization in EMs probably by promoting FoxO1's phosphorylation and FoxO1 nuclear exclusion via hydrolyzing AKT1. The dysregulation of CAPN7 may be a novel cause of EMs.

Disrupted PGR-B and ESR1 signaling underlies defective decidualization linked to severe preeclampsia

Background:

Decidualization of the uterine mucosa drives the maternal adaptation to invasion by the placenta. Appropriate depth of placental invasion is needed to support a healthy pregnancy; shallow invasion is associated with the development of severe preeclampsia (sPE). Maternal contribution to sPE through failed decidualization is an important determinant of placental phenotype. However, the molecular mechanism underlying the in vivo defect linking decidualization to sPE is unknown.

Methods:

Global RNA sequencing was applied to obtain the transcriptomic profile of endometrial biopsies collected from nonpregnant women who suffer sPE in a previous pregnancy and women who did not develop this condition. Samples were randomized in two cohorts, the training and the test set, to identify the fingerprinting encoding defective decidualization in sPE and its subsequent validation. Gene Ontology enrichment and an interaction network were performed to deepen in pathways impaired by genetic dysregulation in sPE. Finally, the main modulators of decidualization, estrogen receptor 1 (ESR1) and progesterone receptor B (PGR-B), were assessed at the level of gene expression and protein abundance.

Results:

Here, we discover the footprint encoding this decidualization defect comprising 120 genes—using global gene expression profiling in decidua from women who developed sPE in a previous pregnancy. This signature allowed us to effectively segregate samples into sPE and control groups. ESR1 and PGR were highly interconnected with the dynamic network of the defective decidualization fingerprint. ESR1 and PGR-B gene expression and protein abundance were remarkably disrupted in sPE.

Conclusions:

Thus, the transcriptomic signature of impaired decidualization implicates dysregulated hormonal signaling in the decidual endometria in women who developed sPE. These findings reveal a potential footprint that could be leveraged for a preconception or early prenatal screening of sPE risk, thus improving prevention and early treatments.

Funding:

This work has been supported by the grant PI19/01659 (MCIU/AEI/FEDER, UE) from the Spanish Carlos III Institute awarded to TGG. NCM was supported by the PhD program FDGENT/2019/008 from the Spanish Generalitat Valenciana. IMB was supported by the PhD program PRE2019-090770 and funding was provided by the grant RTI2018-094946-B-100 (MCIU/AEI/FEDER, UE) from the Spanish Ministry of Science and Innovation with CS as principal investigator. This research was funded partially by Igenomix S.L.

The role of epigenetic mechanisms in the regulation of gene expression in the cyclical endometrium

BACKGROUND

The human endometrium is a highly dynamic tissue whose function is mainly regulated by the ovarian steroid hormones estradiol and progesterone. The serum levels of these and other hormones are associated with three specific phases that compose the endometrial cycle: menstrual, proliferative, and secretory. Throughout this cycle, the endometrium exhibits different transcriptional networks according to the genes expressed in each phase. Epigenetic mechanisms are crucial in the fine-tuning of gene expression to generate such transcriptional networks. The present review aims to provide an overview of current research focused on the epigenetic mechanisms that regulate gene expression in the cyclical endometrium and discuss the technical and clinical perspectives regarding this topic.

MAIN BODY

The main epigenetic mechanisms reported are DNA methylation, histone post-translational modifications, and non-coding RNAs. These epigenetic mechanisms induce the expression of genes associated with transcriptional regulation, endometrial epithelial growth, angiogenesis, and stromal cell proliferation during the proliferative phase. During the secretory phase, epigenetic mechanisms promote the expression of genes associated with hormone response, insulin signaling, decidualization, and embryo implantation. Furthermore, the global content of specific epigenetic modifications and the gene expression of non-coding RNAs and epigenetic modifiers vary according to the menstrual cycle phase. In vitro and cell type-specific studies have demonstrated that epithelial and stromal cells undergo particular epigenetic changes that modulate their transcriptional networks to accomplish their function during decidualization and implantation.

CONCLUSION AND PERSPECTIVES

Epigenetic mechanisms are emerging as key players in regulating transcriptional networks associated with key processes and functions of the cyclical endometrium. Further studies using next-generation sequencing and single-cell technology are warranted to explore the role of other epigenetic mechanisms in each cell type that composes the endometrium throughout the menstrual cycle. The application of this knowledge will definitively provide essential information to understand the pathological mechanisms of endometrial diseases, such as endometriosis and endometrial cancer, and to identify potential therapeutic targets and improve women's health.

YTHDF2 inhibit the tumorigenicity of endometrial cancer via downregulating the expression of IRS1 methylated with m6A

RNA epigenetic modification take part in many biology processes, and the N6-methyladenosine (m⁶A) methylation of specific mRNAs in endometrial cancer (EC) tissues play a key role in regulating the tumorigenicity of EC, but the specific mechanism still unknown and need to be investigated in the future. Here, we found that m⁶A reader protein YTHDF2 expression was significantly upregulated in EC compare to tumor adjacent tissues, YTHDF2 was then identified to inhibit the proliferation and invasion of EC cell lines. Mechanistically, the m⁶A reader YTHDF2 bind the methylation sites of target transcripts IRS1 and promoted IRS1 mRNA degradation, consequently inhibiting the expression of IRS1 and inhibiting IRS1/AKT signaling pathway, finally inhibit the tumorigenicity of EC. Thus, we demonstrated that YTHDF2 inhibited the proliferation and invasion of EC via inhibiting IRS1 expression in m⁶A epigenetic way, which suggests a potential therapeutic target for EC.

Pluripotent stem cell-derived endometrial stromal fibroblasts in a cyclic, hormone-responsive, coculture model of human decidua

Various human diseases and pregnancy-related disorders reflect endometrial dysfunction. However, rodent models do not share fundamental biological processes with the human endometrium, such as spontaneous decidualization, and no existing human cell cultures recapitulate the cyclic interactions between endometrial stromal and epithelial compartments necessary for decidualization and implantation. Here we report a protocol differentiating human pluripotent stem cells into endometrial stromal fibroblasts (PSC-ESFs) that are highly pure and able to decidualize. Coculture of PSC-ESFs with placenta-derived endometrial epithelial cells generated organoids used to examine stromal-epithelial interactions. Cocultures exhibited specific endometrial markers in the appropriate compartments, organization with cell polarity, and hormone responsiveness of both cell types. Furthermore, cocultures recapitulate a central feature of the human decidua by cyclically responding to hormone withdrawal followed by hormone retreatment. This advance enables mechanistic studies of the cyclic responses that characterize the human endometrium.

The role of mesenchymal-epithelial transition in endometrial function

BACKGROUND

The human uterine endometrium undergoes significant remodeling and regeneration on a rapid and repeated basis, after parturition, menstruation, and in some cases, injury. The ability of the adult endometrium to undergo cyclic regeneration and differentiation/decidualization is essential for successful human reproduction. Multiple key physiologic functions of the endometrium require the cells of this tissue to transition between mesenchymal and epithelial phenotypes, processes known as mesenchymal-epithelial transition (MET) and epithelial-mesenchymal transition (EMT). Although MET/EMT processes have been widely characterized in embryonic development and in the context of malignancy, mounting evidence demonstrates the importance of MET/EMT in allowing the endometrium the phenotypic and functional flexibility necessary for successful decidualization, regeneration/re-epithelialization and embryo implantation.

OBJECTIVE AND RATIONALE

The objective of this review is to provide a comprehensive summary of the observations concerning MET and EMT and their regulation in physiologic uterine functions, specifically in the context of endometrial regeneration, decidualization and embryo implantation.

SEARCH METHODS

Using variations of the search terms 'mesenchymal-epithelial transition', 'mesenchymal-epithelial transformation', 'epithelial-mesenchymal transition', 'epithelial-mesenchymal transformation', 'uterus', 'endometrial regeneration', 'endometrial decidualization', 'embryo implantation', a search of the published literature between 1970 and 2018 was conducted using the PubMed database. In addition, we searched the reference lists of all publications included in this review for additional relevant original studies.

OUTCOMES

Multiple studies demonstrate that endometrial stromal cells contribute to the regeneration of both the stromal and epithelial cell compartments of the uterus, implicating a role for MET in mechanisms responsible for endometrial regeneration and re-epithelialization. During decidualization, endometrial stromal cells undergo morphologic and functional changes consistent with MET in order to accommodate embryo implantation. Under the influence of estradiol, progesterone and multiple other factors, endometrial stromal fibroblasts acquire epithelioid characteristics, such as expanded cytoplasm and rough endoplasmic reticulum required for greater secretory capacity, rounded nuclei, increased expression of junctional proteins which allow for increased cell-cell communication, and a reorganized actin cytoskeleton. During embryo implantation, in response to both maternal and embryonic-derived signals, the maternal luminal epithelium as well as the decidualized stromal cells acquire the mesenchymal characteristics of increased migration/motility, thus undergoing EMT in order to accommodate the invading trophoblast.

WIDER IMPLICATIONS

Overall, the findings support important roles for MET/EMT in multiple endometrial functions required for successful reproduction. The endometrium may be considered a unique wound healing model, given its ability to repeatedly undergo repair without scarring or loss of function. Future studies to elucidate how MET/EMT mechanisms may contribute to scar-free endometrial repair will have considerable potential to advance studies of wound healing mechanisms in other tissues.

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.

Difference of Cyclooxygenase-2 (COX2) Expression in Endometrium Between Patients with Polycystic Ovary Syndrome (PCOS) and Fertile Women

Objective: The study was conducted to determine whether there were differences in COX-2 expression in endometrial women with PCOS compared to fertile women.

Methods: This study is a case-control study investigating the relationship between exposure (research factors) and disease, by comparing case group and control group based on their exposure status. The samples of this study were infertile polycystic ovary syndrome patients who were treated at the Sekar Fertility Clinic in Dr. Moewardi Hospital Surakarta, and fertile women seeking treatment at Dr. Moewardi Hospital Surakarta. The number of samples were 60 subjects consisting of 30 PCOS patients and 30 fertile women. The expression of COX-2 in endometrial biopsy LH + 5 until LH + 10 which meet the inclusion with Rotterdam criteria and exclusion criteria was checked by immunohistochemistry. The data was analyzed using the Mann-Whitney test.

Results: The mean COX-2 expression in PCOS (10.83 ± 5.35) in fertile women (37.00 ± 7.76), p = 0.005. Regression test of COX-2 by adjusting external variables (occupation, age, education, menstrual disorders, familial history, menstrual cycle, menarche, obesity, contraception history) shows also higher expression in PCOS patient with OR = -7.063; CI = 0.462–108.066; p = 0.160.

Conclusion: COX-2 expression in endometrium of women with PCOS is lower than it is in fertile women.

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.

FUT8 drives the proliferation and invasion of trophoblastic cells via IGF-1/IGF-1R signaling pathway

INTRODUCTION

Trophoblast proliferation and invasion are essential for embryo implantation and placentation. Protein glycosylation is one of the most common and vital post-translational modifications, regulates protein physical and biochemical properties. FUT8 is the only known fucosyltransferase responsible for catalyzing α1,6-fucosylation in mammals, and α1,6-fucosylated glycoproteins are found to participate in various physiopathological processes. However, whether FUT8/α1,6-fucosylation modulates the functions of trophoblastic cells remains elusive.

METHODS

FUT8 in human placenta villi during 6-8 gestational weeks and trophoblastic cells were detected by Western blot and immunofluorescent staining. α1,6-fucosylation in tissues or cells were measured by Lectin LCA (Lens culinaris) fluorescent staining and Lectin blot. FUT8 expression was down-regulated by siRNA transfection in JAR and JEG-3 cells, and cell viability, motility and invasiveness ability were detected by the functional experiments. α1,6-fucosylation of insulin-like growth factor receptor (IGF-1R) was examined by immunoprecipitation, and the amount of phosphorylated IGF-1R was detected in FUT8 down-regulated JAR cells.

RESULTS

Human placenta villi and trophoblastic cells expressed FUT8/α1,6-fucosylation. Knockdown FUT8 by siRNA transfection suppressed the proliferation, epithelial-mesenchymal transition, migration and invasion of JAR and JEG-3 cells. Furthermore, we found that FUT8 modified the α1,6-fucosylation of IGF-1R, and regulated IGF-1 dependent activation of IGF-1R, MAPK and PI3K/Akt signaling pathways in JAR cells.

CONCLUSIONS

Our results implicate a critical role for FUT8 in maintaining the normal functions of trophoblastic cells, suggesting manipulating FUT8 may be an effective approach in pregnancy.

Differential regulation of mTORC1 and mTORC2 is critical for 8-Br-cAMP-induced decidualization

Human endometrium decidualization, a differentiation process involving biochemical and morphological changes, is a prerequisite for embryo implantation and successful pregnancy. Here, we show that the mammalian target of rapamycin (mTOR) is a crucial regulator of 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP)-induced decidualization in human endometrial stromal cells. The level of mSin1 in mTOR complex 2 (mTORC2) and DEPTOR in mTOR complex 1 (mTORC1) decreases during 8-Br-cAMP-induced decidualization, resulting in decreased mTORC2 activity and increased mTORC1 activity. Notably, DEPTOR displacement increases the association between raptor and insulin receptor substrate-1 (IRS-1), facilitating IRS-1 phosphorylation at serine 636/639. Finally, both S473 and T308 phosphorylation of Akt are reduced during decidualization, followed by a decrease in forkhead box O1 (FOXO1) phosphorylation and an increase in the mRNA levels of the decidualization markers prolactin (PRL) and insulin-like growth factor-binding protein-1 (IGFBP-1). Taken together, our findings reveal a critical role for mTOR in decidualization, involving the differential regulation of mTORC1 and mTORC2.

Defective decidualization during and after severe preeclampsia reveals a possible maternal contribution to the etiology

In preeclampsia (PE), cytotrophoblast (CTB) invasion of the uterus and spiral arteries is often shallow. Thus, the placenta's role has been a focus. In this study, we tested the hypothesis that decidual defects are an important determinant of the placental phenotype. We isolated human endometrial stromal cells from nonpregnant donors with a previous pregnancy that was complicated by severe PE (sPE). Compared with control cells, they failed to decidualize in vitro as demonstrated by morphological criteria and the analysis of stage-specific antigens (i.e., IGFBP1, PRL). These results were bolstered by global transcriptional profiling data that showed they were transcriptionally inert. Additionally, we used laser microdissection to isolate the decidua from tissue sections of the maternal-fetal interface in sPE. Global transcriptional profiling revealed defects in gene expression. Also, decidual cells from patients with sPE, which dedifferentiated in vitro, failed to redecidualize in culture. Conditioned medium from these cells failed to support CTB invasion. To mimic aspects of the uterine environment in normal pregnancy, we added PRL and IGFBP1, which enhanced invasion. These data suggested that failed decidualization is an important contributor to down-regulated CTB invasion in sPE. Future studies will be aimed at determining whether this discovery has translational potential with regard to assessing a woman's risk of developing this pregnancy complication.

Exposure of decidualized HIESC to low oxygen tension and leucine deprivation results in increased IGFBP-1 phosphorylation and reduced IGF-I bioactivity

Phosphorylation of decidual IGFBP-1 enhances binding of IGF-I, limiting the bioavailability of this growth factor which may contribute to reduced placental and fetal growth. The mechanisms regulating decidual IGFBP-1 phosphorylation are incompletely understood. Using decidualized human immortalized endometrial stromal cells we tested the hypothesis that low oxygen tension or reduced leucine availability, believed to be common in placental insufficiency, increase the phosphorylation of decidual IGFBP-1. Multiple reaction monitoring-MS (MRM-MS) was used to quantify IGFBP-1 phosphorylation. MRM-MS validated the novel phosphorylation of IGFBP-1 at Ser58, however this site was unaffected by low oxygen tension/leucine deprivation. In contrast, significantly elevated phosphorylation was detected for pSer119, pSer98/pSer101 and pSer169/pSer174 sites. Immunoblotting and dual-immunofluorescence using phosphosite-specific IGFBP-1 antibodies further demonstrated increased IGFBP-1 phosphorylation in HIESC under both treatments which concomitantly reduced IGF-I bioactivity. These data support the hypothesis that down regulation of IGF-I signaling links decidual IGFBP-1 hyperphosphorylation to restricted fetal growth in placental insufficiency.

miR-182 aids in receptive endometrium development in dairy goats by down-regulating PTN expression

Increasing evidence has shown that miRNAs play important roles in endometrium development during the menstrual cycle in humans and many other animals. Our previous data indicated that miR-182 levels increase 15.55-fold and pleiotrophin (PTN) levels decrease 20.97-fold in the receptive endometrium (RE, D15) compared with the pre-receptive endometrium (PE, D5) in dairy goats. The present study shows that miR-182 is widely expressed in different tissues of dairy goats and that its expression levels are regulated by E2 and P4 in endometrial epithelium cells (EECs). We confirmed that PTN is a target of miR-182 and that miR-182 regulates the protein levels of AKT, Bcl-2, FAS, MAPK, Caspase-3 and SP1 in EECs. Furthermore, miR-182 up-regulates or maintains the expression levels of osteopontin (OPN), cyclooxygenase-2 (COX-2) and prolactin receptor (PRLR) in EECs, suggesting that miR-182 is an important regulatory factor in the construction of endometrial receptivity in dairy goats. In conclusion, miR-182 participates in the development of endometrial receptivity by down-regulating PTN and affecting the expression of select apoptosis-related genes and increasing or maintaining the expression levels of OPN, COX-2 and PRLR in the EECs of dairy goats.

Progesterone-Regulated Endometrial Factors Controlling Implantation

The steroid hormone progesterone (P), acting via the progesterone receptor (PR) isoforms, PR-A and PR-B, exerts a profound influence on uterine functions during early gestation. In recent years, chromatin immunoprecipitation-sequencing in combination with microarray-based gene expression profiling analyses have revealed that the PR isoforms control a substantially large cistrome and transcriptome during endometrial differentiation in the human and the mouse. Genetically engineered mouse models have established that several PR-regulated genes, such as Ihh, Bmp2, Hoxa10, and Hand2, are essential for implantation and decidualization. PR-A and PR-B also collaborate with other transcription factors, such as FOS, JUN, C/EBPβ and STAT3, to regulate the expression of many target genes that functions in concert to properly control uterine epithelial proliferation, stromal differentiation, angiogenesis, and local immune response to render the uterus 'receptive' and allow embryo implantation. This review article highlights recent work describing the key PR-regulated pathways that govern critical uterine functions during establishment of pregnancy.

In vitro decidualisation of canine uterine stromal cells

BACKGROUND

The uterine response to the presence of embryos is poorly understood in the domestic dog (Canis familiaris). The intimate embryo-maternal cross-talk, which begins following the hatching of blastocysts and embryo attachment leads to strong structural and functional remodelling of the uterus. A part of this process is decidualisation, comprising morphological and biochemical changes that result in formation of maternal stroma-derived decidual cells. These are an integral part of the canine placenta materna, which together with the maternal vascular endothelium are the only cells of the canine endotheliochorial placenta able to resist trophoblast invasion. These cells are also the only ones within the canine placenta expressing the progesterone receptor (PGR). Understanding the decidualisation process thus appears essential for understanding canine reproductive physiology.

METHODS

Here, we investigated the capability of canine uterine stromal cells to decidualise in vitro, thereby serving as a canine model of decidualisation. A dbcAMP-mediated approach was chosen during a time course of 24 - 72 h. Tissue material from six (n = 6) healthy, dioestric bitches was used (approximately 2 weeks after ovulation). Cells were characterized by differential staining, nearly 100 % of which were vimentin-positive. Scanning and transmission electron microscope analyses were applied, and morphological changes were recorded with a live cell imaging microscope. Expression of several decidualisation markers was investigated.

RESULTS

The in vitro cultured stromal cells acquired characteristics of decidual cells when incubated with 0.5 mM dbcAMP for 72 h. Their shape changed from elongated to rounded, while ultrastructural analysis revealed higher numbers of mitochondria and secretory follicles, and an increased proliferation rate. Elevated expression levels of IGF1, IGF2, PRLR and ERα were observed in decidualised cells; PRL and ERβ remained mostly below the detection limit, while PGR remained unaffected. The expression of smooth muscle α actin (αSMA), another decidualisation marker, was strongly induced. Among prostaglandin system members, levels of COX2 (PTGS2) and of PGE2-synthase (PTGES) were upregulated. Expression of the PGE2 receptors, PTGER2 and PTGER4, was clearly detectable.

CONCLUSION

An in vitro decidualisation model with canine uterine stromal cells was successfully established, allowing future, more detailed studies to be undertaken on the underlying molecular and endocrine mechanisms of canine decidualisation.

Influence of Cancer-Associated Endometrial Stromal Cells on Hormone-Driven Endometrial Tumor Growth

Cancer-associated fibroblasts have been shown to inhibit or stimulate tumor growth depending on stage, grade, and tumor type. It remains unclear, however, the effect of endometrial-cancer-associated fibroblasts on hormone-driven responses in endometrial cancer. In this study, we investigated the effect of normal and cancer-associated stromal cells from patients with and without endometrial cancer on endometrial tumor growth in response to estradiol (E2) and progesterone (P4). Compared to benign endometrial stromal cells, the low-grade and high-grade cancer-associated stromal cells exhibited a blunted hormone response for proliferation as well as IGFBP1 secretion. Additional analysis of the influence of stromal cells on hormone-driven tumor growth was done by mixing stromal cells from benign, low-grade, or high-grade tumors, with Ishikawa cells for subcutaneous tumor formation. The presence of both benign and high-grade cancer-associated stromal cells increased estradiol-driven xenografted tumor growth compared to Ishikawa cells alone. Low-grade cancer-associated stromal cells did not significantly influence hormone-regulated tumor growth. Addition of P4 attenuated tumor growth in Ishikawa + benign or high-grade stromal cells, but not in Ishikawa cells alone or with low-grade stromal cells. Using an angiogenesis focused real-time array TGFA, TGFB2 and TGFBR1 and VEGFC were identified as potential candidates for hormone-influenced growth regulation of tumors in the presence of benign and high-grade stromal cells. In summary, endometrial-cancer-associated cells responded differently to in vitro hormone treatment compared to benign endometrial stromal cells. Additionally, presence of stromal cells differentially influenced hormone-driven xenograft growth in vivo depending on the disease status of the stromal cells.

Roles of progesterone receptor A and B isoforms during human endometrial decidualization

Progesterone, acting through the progesterone receptors (PGRs), is one of the most critical regulators of endometrial differentiation, known as decidualization, which is a key step toward the establishment of pregnancy. Yet a long-standing unresolved issue in uterine biology is the precise roles played by the major PGR isoforms, PGR-A and PGR-B, during decidualization in the human. Our approach, expressing PGR-A and PGR-B individually after silencing endogenous PGRs in human endometrial stromal cells (HESCs), enabled the analysis of the roles of these isoforms separately as well as jointly. Chromatin immunoprecipitation-sequencing in combination with gene expression profiling revealed that PGR-B controls a substantially larger cistrome and transcriptome than PGR-A during HESC differentiation. Interestingly, PGR-B directly regulates the expression of PGR-A. De novo motif analysis indicated that, although the 2 isoforms bind to the same DNA sequence motif, there are both common and unique neighboring motifs where other transcription factors, such as FOSL1/2, JUN, C/EBPβ, and STAT3, bind and dictate the transcriptional activities of these isoforms. We found that PGR-A and PGR-B regulate overlapping as well as distinct sets of genes, many of which are known to be critical for decidualization and establishment of pregnancy. When PGR-A and PGR-B were coexpressed during HESC differentiation, PGR-B played a predominant role, although both isoforms influenced each other's transcriptional activity. This study revealed the gene networks that operate downstream of each PGR isoform to mediate critical functions, such as regulation of the cell cycle, angiogenesis, lysosomal activation, insulin receptor signaling, and apoptosis, during decidualization in the human.

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.

Regulation of endometrial receptivity by the highly expressed HOXA9, HOXA11 and HOXD10 HOX-class homeobox genes

STUDY QUESTION

Are other HOX genes, in addition to HOXA10, involved in endometrial receptivity?

SUMMARY ANSWER

The highly expressed HOXA9, HOXA11 and HOXD10 genes also appear to be involved in endometrial receptivity.

WHAT IS KNOWN ALREADY

Within the HOX family of homeobox transcription factor genes are the leading candidates for the regulation of embryonic implantation. A crucial role of HOXA10 in endometrial receptivity has been well established.

STUDY DESIGN, SIZE, DURATION

To identify HOX candidate genes, we performed data mining on all 39 human HOX genes in the 'Human body index' gene expression database of normal human tissue. The temporal and spatial expression pattern of four highly expressed HOX genes in the human endometrium was determined. To further investigate the function of these Hox genes, we used a robust in vivo mouse model in which we blocked maternal Hox gene expression.

PARTICIPANTS/MATERIALS, SETTING AND METHODS

Analysis of a gene expression profile set in the public domain consisting of 504 samples representing 95 different normal human tissues, showed that in addition to HOXA10, also HOXA9, HOXA11, HOXB6 and HOXD10 mRNA showed increased expression in the human endometrium (16 samples). The temporal and spatial expression pattern of these four HOX genes throughout the menstrual cycle was determined in the endometrium from 27 female patients eligible for IVF-embryo transfer with a normal cycle by quantitative real-time PCR (qRT-PCR), western blot and immunohistochemistry. The role of maternal Hoxa9, Hoxa11 and Hoxd10 was assessed in a mouse implantation model by expression knockdown using RNA interference. Forty mice were transfected with Hoxa9-, Hoxa11- or Hoxd10-specific small hairpin RNA (shRNA) constructs or a vector control by injection into the uterine horn at Day 2 after vaginal plug detection (Day 1) (160 mice in total). The effects were examined by qRT-PCR and western blot at Day 4 and litter sizes counted at Day 9 of pregnancy.

MAIN RESULTS AND THE ROLE OF CHANCE

HOXA10, HOXA9, HOXA11 and HOXD10 all showed increased expression during the mid-secretory phase of the menstrual cycle (P < 0.01). Knockdown of Hoxa9, Hoxa11 and Hoxd10 in the murine uterus resulted in significantly reduced average implantation rates (P < 0.01) and, with regard to four Hox target genes, also correlated with a significantly increased empty spiracles homolog 2 (Emx2) and insulin-like growth factor binding protein-1 (Igfbp1), and decreased integrin β3 (Itgb3) and leukemia inhibitory factor (Lif), expression (P < 0.01).

LIMITATIONS, REASONS FOR CAUTION

Menstrual cycle stage was not confirmed by serum hormone analysis. We verified the absence of significant differences in stage-specific expression of the reference genes used in our study (ACTB/Actb and GAPDH/Gapdh) and therefore possible limitations of this approach were minimized. In addition, the translatability of our data from a mouse model to patients needs to be investigated further.

WIDER IMPLICATIONS OF THE FINDINGS

We provide evidence that three other HOX genes in addition to HOXA10 are involved in endometrial receptivity, and that part of their function is asserted through several known HOX target genes, suggesting the presence of a central HOX signal transduction pathway.

Diverse roles of prostaglandins in blastocyst implantation

Prostaglandins (PGs), derivatives of arachidonic acid, play an indispensable role in embryo implantation. PGs have been reported to participate in the increase in vascular permeability, stromal decidualization, blastocyst growth and development, leukocyte recruitment, embryo transport, trophoblast invasion, and extracellular matrix remodeling during implantation. Deranged PGs syntheses and actions will result in implantation failure. This review summarizes up-to-date literatures on the role of PGs in blastocyst implantation which could provide a broad perspective to guide further research in this field.

Endometrial signaling pathways during ovarian stimulation for assisted reproduction technology

OBJECTIVE

To determine the effects of different hormonal levels on endometrial biochemical development during ovulation induction for assisted reproduction technology (ART) cycles.

DESIGN

Prospective controlled study.

SETTING

University center.

PATIENT(S)

Nine women during a natural cycle (control) and 9 oocyte donors (treated) during an ART cycle.

INTERVENTION(S)

At the time consistent with day 3 embryo transfer (LH+5 in control, hCG+5 in treated), transvaginal ultrasound, endometrial biopsy, and blood sampling were performed. Real-time reverse-transcription polymerase chain reaction was used to measure mRNA levels for insulin receptor (InsR), type I IGF receptor (IGFRI), prolactin receptor (PRL-R), androgen receptor (AR), TSH receptor (TSHR), nuclear receptors for T3 and T4 (TRα1, TRα2, and TRβ1), iodothyronine deiodinase (DIO2), and 1,25-dihydroxyvitamin D3 receptor (VDR) in the endometrial tissue.

MAIN OUTCOME MEASURE(S)

Biochemical endometrial development.

RESULT(S)

IGFRI mRNA levels were 69% lower in treated patients than in control subjects, 0.12 ± 0.005 pg/μg RNA versus 0.39 ± 0.01 pg/μg RNA. TSHR mRNA was 57% lower, 2.6 ± 0.1 fg/μg RNA versus 6.0 ± 0.2 fg/μg RNA. TRα1 and TRα2 mRNA did not change, but TRβ1 mRNA levels were 63% higher. DIO2 mRNA was 63% lower, 1.2 ± 0.07 pg/μg RNA versus 3.2 ± 0.2 pg/μg RNA. InsR mRNA levels, despite being 68% lower in treated patients, did not reach significance, and PRL-R, AR, and VDR did not significantly change.

CONCLUSION(S)

Exposure of the endometrium to ovarian stimulation appears to influence insulin and thyroid hormone signaling pathways in the decidua at day 3 embryo transfer, whereas prolactin, androgen, and vitamin D pathways are uninfluenced. These findings echo the known delayed endometrial maturation during ovarian stimulation.

Preimplantation human blastocyst-endometrial interactions: the role of inflammatory mediators

Immune factors such as cytokines, chemokines, and growth factors are known to play important roles in the preimplantation interactions and communication between the blastocyst and receptive endometrium. This crucial dialog occurs during the stages when the blastocyst is in the uterine cavity immediately preceding implantation and the establishment of pregnancy. Human preimplantation processes are difficult to study due to restrictions on tissue availability. This review focuses on the expression and role of immune factors in human blastocyst-endometrial dialog during the very early stages of implantation. It highlights the importance of immune regulators and the need to develop new models to study human implantation.

Effect of single post-ovulatory administration of levonorgestrel on gene expression profile during the receptive period of the human endometrium

The hypothesis that levonorgestrel (LNG) used as an emergency contraceptive interferes with endometrial receptivity remains unproven. We compared the endometrial gene expression profile during the receptive period after administering a single dose of LNG 1.5 mg or placebo on day 1 of the luteal phase. An endometrial biopsy was done on day LH+7 or LH+8 and samples were taken from seven volunteers, each one contributing with one cycle treated with placebo and another with LNG. The expression of 20 383 genes was determined using cDNA microarrays. Real-time RT-PCR was used 1) to confirm the differences found in DNA microarray analysis and 2) to determine the effect of LNG on transcript levels of C3, C4BPα, COX2, MAOA, S100A4, and SERPINB9, known to be upregulated during receptivity, and on cPLA2α, JAK1, JNK1, CTSL1, and GSTP1, known to respond to mifepristone. Additional endometrial biopsies were done during the pre-receptive (LH+3) and receptive (LH+7) period and samples were taken from eight untreated volunteers in order to determine the changes associated with acquisition of receptivity of 14 genes. Mean levels of PAEP, TGM2, CLU, IGF2, and IL6ST mRNAs increased after administering LNG while those of HGD, SAT1, EVA1, LOC90133, ANXA1, SLC25A29, CYB5A, CRIP1, and SLC39A14 decreased. Except for the level of ANXA1 transcript, all changes remained within the range observed in untreated controls, and none of the transcripts responding to mifepristone changed in response to LNG. Post-ovulatory administration of LNG caused minimal changes in gene expression profiling during the receptive period. Neither the magnitude nor the nature or direction of the changes endorses the hypothesis that LNG interferes with endometrial receptivity.

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.

Influence of energy balance on the somatotrophic axis and matrix metalloproteinase expression in the endometrium of the postpartum dairy cow

Postpartum dairy cows enter a period of negative energy balance (NEB) associated with low circulating IGF1, during which the uterus must undergo extensive repair following calving. This study investigated the effects of NEB on expression of IGF family members and related genes in the involuting uterus. Cows were allocated to two treatments using differential feeding and milking regimes to produce mild NEB or severe NEB (SNEB). Uterine endometrial samples collected 2 weeks post partum were analysed by quantitative PCR. The expression of IGF-binding protein 4 (IGFBP4) mRNA increased in the endometrium of SNEB cows, with trends towards increased IGFBP1 and reduced IGFBP6 expression. There were no significant differences between treatments in mRNA expression of IGF1, IGF2 or of any hormone receptor studied, but significant correlations across all cows in the expression levels of groups of receptors suggested common regulatory mechanisms: type 1 IGF receptor (IGF1R), IGF2R and insulin receptor (INSR); GHR with ESR1; and ESR2 with NR3C1. The expression of IGF1R and INSR also positively correlated with the circulating urea concentration. Matrix metalloproteinases (MMPs) are important in tissue remodelling and can affect IGF signalling via interaction with IGFBPs. The expression levels of MMP1, MMP3, MMP9 and MMP13 mRNAs all showed major upregulation in the endometrium of cows in SNEB and all except MMP9 were highly correlated with expression of IGFBP4. Alpha(2)-HS-glycoprotein (AHSG) and PDK4, two genes implicated in insulin resistance, were also highly expressed in SNEB. These results suggest that cows in SNEB experience alterations to the IGF and insulin signalling pathways in the postpartum endometrium. This may affect the rate of tissue repair with a possible negative impact on subsequent fertility.

Insulin receptor substrate-2 gene polymorphism: is it associated with endometrial cancer?

OBJECTIVE

The G1057D polymorphism in the insulin receptor substrate-2 (IRS-2) gene has been reported to be associated with insulin resistance, obesity and type 2 diabetes. However little is known about its possible association with cancer. To investigate this association, we determined the distribution of its genotypes and frequency of alleles in endometrial cancer patients.

METHODS

The study population consisted of 184 subjects: 44 patients with endometrial cancer and 140 controls without cancer. All the patients were primarily treated with surgical intervention. DNA was extracted from the leucocytes by high pure polymerase chain reaction (PCR) template preparation kit. Genetic polymorphism of IRS-2 G1057D was detected by using PCR-based restriction fragment-length polymorphism.

RESULTS

For IRS-2 G1057D polymorphism, there was a significant difference in genotype distribution and allele frequency between endometrial cancer patients and controls (p < 0.001). The risk for endometrial cancer was 4.87 times higher in the individuals with the IRS-2 DD genotype compared to the GG genotype [95% confidence interval (CI): 1.74-13.63 p = 0.003]. Also individuals with the IRS-2 D allele had a significantly higher risk of endometrium cancer compared with individuals with the IRS-2 G allele, with a relative risk of 2.23 (95% CI: 1.36-3.67, p = 0.001) for cases compared with population controls.

CONCLUSION

These results suggest that IRS-2 G1057D polymorphism may be associated with endometrial cancer.

Association of G1057D variant of insulin receptor substrate-2 with endometriosis

OBJECTIVE

To investigate whether the insulin receptor substrate (IRS)-2 G1057D polymorphism is associated with the risk of endometriosis, and to evaluate potential correlation of IRS2 gene polymorphism with the stages of endometriosis.

DESIGN

Case-control study.

SETTING

Gynecology clinics in university hospital.

PATIENT(S)

Women with (n = 135) or without (n = 135) endometriosis. Afterward, the women with endometriosis were divided into two groups according to the stage: group 1 included 63 women in stages I-II, and group 2 included 72 women in stages III-IV.

INTERVENTION(S)

Genotyping by polymerase chain reaction-based restriction fragment-length polymorphism method.

MAIN OUTCOME MEASURE(S)

Genotype distribution of the G1057D polymorphism in the IRS2 gene.

RESULT(S)

The genotype distribution of the IRS2 G1057D polymorphism in the endometriosis group was significantly different from that of the control group (GG/GD/DD rates were 43.0%/39.3%/17.7% and 55.6%/36.3%/8.1% for the endometriosis and control groups, respectively). Further subgroup analyses according to the stage of endometriosis also revealed a positive association between the IRS2 DD genotype expression and stage III-IV endometriosis patients in the population studied.

CONCLUSION(S)

These results suggest that the IRS2 G1057D polymorphism may be associated with an increased risk for endometriosis.