Regulation of steroidogenic acute regulatory protein expression and progesterone production in endometriotic stromal cells

Digestive system deep infiltrating endometriosis: What do we know

Digestive system infiltrating endometriosis (DSIE) is an uncommon form of endometriosis in the digestive system. DSIE often occurs in the intestines (especially the sigmoid rectum), liver, gallbladder and pancreas. Clinically, DSIE presents with the same symptoms as endometriosis, including cyclic pain, bleeding and infertility, in addition to specific biliary/intestinal obstruction and gastrointestinal bleeding. Compared to general endometriosis, DSIE has unique biological behaviour and pathophysiological mechanisms. Most DSIEs are deep invasive endometrioses, characterized by metastasis to the lymph nodes and lymphatic vessels, angiogenesis, peripheral nerve recruitment, fibrosis and invasion of surrounding tissues. DSIE-related peripheral angiogenesis is divided into three patterns: angiogenesis, vasculogenesis and inosculation. These patterns are regulated by interactions between multiple hypoxia-hormone cytokines. The nerve growth factors regulate the extensive neurofibril recruitment in DSIE lesions, which accounts for severe symptoms of deep pain. They are also associated with fibrosis and the aggressiveness of DSIE. Cyclic changes in DSIE lesions, recurrent inflammation and oxidative stress promote repeated tissue injury and repair (ReTIAR) mechanisms in the lesions, accelerating fibril formation and cancer-related mutations. Similar to malignant tumours, DSIE can also exhibit aggressiveness derived from collective cell migration mediated by E-cadherin and N-cadherin. This often makes DSIE misdiagnosed as a malignant tumour of the digestive system in clinical practice. In addition to surgery, novel treatments are urgently required to effectively eradicate this lesion.

Elevated phosphorylation of estrogen receptor α at serine-118 in ovarian endometrioma

OBJECTIVE

To evaluate the phosphorylation of estrogen receptor α at serine-118 (phospho-ERα S118) in the endometrium, ovarian endometrioma, and deep infiltrating endometriosis (DIE).

DESIGN

Experimental study.

SETTING

University-affiliated hospital and academic research laboratory.

PATIENT(S)

Twenty-five patients underwent a hysterectomy, 18 patients underwent surgical removal of ovarian endometrioma, and 6 patients underwent DIE.

INTERVENTION(S)

Tissue samples were obtained from patients who underwent surgical procedures.

MAIN OUTCOME MEASURE(S)

Immunostaining for phospho-ERα S118, ERα, or phosphorylated p44/42 mitogen-activated protein kinase (phospho-p44/42 MAPK) was performed to evaluate the endometrium with or without endometriosis, ovarian endometrioma, and DIE. For in vitro analysis, endometrial epithelial cells (Ishikawa cells) were stimulated with estradiol (E2) or tumor necrosis factor alpha (TNFα), and the expression levels of phospho-ERα S118 and phospho-p44/42 MAPK were evaluated via Western blotting.

RESULT(S)

First, phospho-ERα S118 level was significantly higher in the glands and stroma of ovarian endometriosis samples than in those of endometrial and DIE samples. Second, colocalization of phospho-p44/42 MAPK and phospho-ERα S118 was observed in the glands of ovarian endometrioma. The proportions of cells strongly expressing phospho-p44/42 and phospho-ERα were 87% in phosphor-p44/42 MAPK-positive cells and 79% in phosphor-ERα-positive cells. Third, E2 stimulation significantly enhanced phospho-ERα S118 after 15 and 30 minutes in in vitro analysis using endometrial epithelial cells. Fourth, TNFα stimulation modestly but significantly enhanced phospho-ERα S118 after 15 and 30 minutes. Fifth, in Ishikawa cells, treatment with a p44/42 inhibitor (PD98059) significantly reduced phospho-ERα S118 by TNFα but not by E2.

CONCLUSION(S)

ERα-S118 phosphorylation was increased in ovarian endometriosis. Our findings may provide a new perspective for understanding the mechanism of increased ERα action in the pathophysiology of endometriosis.

Epigenetic regulation and T-cell responses in endometriosis – something other than autoimmunity

Endometriosis is defined as the presence of endometrial-like glands and stroma located outside the uterine cavity. This common, estrogen dependent, inflammatory condition affects up to 15% of reproductive-aged women and is a well-recognized cause of chronic pelvic pain and infertility. Despite the still unknown etiology of endometriosis, much evidence suggests the participation of epigenetic mechanisms in the disease etiopathogenesis. The main rationale is based on the fact that heritable phenotype changes that do not involve alterations in the DNA sequence are common triggers for hormonal, immunological, and inflammatory disorders, which play a key role in the formation of endometriotic foci. Epigenetic mechanisms regulating T-cell responses, including DNA methylation and posttranslational histone modifications, deserve attention because tissue-resident T lymphocytes work in concert with organ structural cells to generate appropriate immune responses and are functionally shaped by organ-specific environmental conditions. Thus, a failure to precisely regulate immune cell transcription may result in compromised immunological integrity of the organ with an increased risk of inflammatory disorders. The coexistence of endometriosis and autoimmunity is a well-known occurrence. Recent research results indicate regulatory T-cell (Treg) alterations in endometriosis, and an increased number of highly active Tregs and macrophages have been found in peritoneal fluid from women with endometriosis. Elimination of the regulatory function of T cells and an imbalance between T helper cells of the Th1 and Th2 types have been reported in the endometria of women with endometriosis-associated infertility. This review aims to present the state of the art in recognition epigenetic reprogramming of T cells as the key factor in the pathophysiology of endometriosis in the context of T-cell-related autoimmunity. The new potential therapeutic approaches based on epigenetic modulation and/or adoptive transfer of T cells will also be outlined.

Role of AMPK/mTOR, mitochondria, and ROS in the pathogenesis of endometriosis

Endometriosis is the presence of endometrial tissue outside the uterine cavity usually in the ovaries, fallopian tube, and pelvic cavity. It's a chronic enigmatic gynecological condition associated with dysmenorrhea, dyspareunia, pelvic pain, and infertility. Endometriosis lesions exist in a unique microenvironment characterized by increased concentrations of hormones, inflammation, and oxidative stress. This environment promotes cell survival through the binding of membrane receptors and subsequent cascading activation of intracellular kinases that stimulate a cellular response. In endometriosis, well-established signaling pathways, mTOR and AMPK, are altered via steroid hormones and other factors to promote cell growth, migration, and proliferation. This is accompanied by dysfunction in the mitochondria that increase energy production to sustain proliferation demands consequently leading to reactive oxygen species overproduction. This review aims to summarize the role of altered mTOR/AMPK signaling pathway, mitochondrial dysfunction, and reactive oxygen species overproduction along with providing therapeutic and diagnostic approaches. Highlighting these factors would provide a better understanding to reach a coherent theory for the pathogenesis of endometriosis.

Higher fibrotic content of endometriotic lesions is associated with diminished prostaglandin E2 signaling

Purpose

While the prevailing view holds that the prostaglandin E2 (PGE₂) signaling plays a vital role in endometriosis, PGE₂ also is known to be anti-fibrotic. We investigated the immunostaining of COX-2, EP2, and EP4, along with fibrotic content in ovarian endometrioma (OE) and deep endometriosis (DE) lesions, and in OE lesions from adolescent and adult patients. In addition, we evaluated the effect of substrate stiffness on the expression of COX-2, EP2, and EP4 in endometrial stromal cells.

Methods

Immunohistochemistry analysis of COX-2, EP2, and EP4, along with the quantification of lesional fibrosis, was conducted for OE and DE lesion samples and also OE lesion samples from adolescent and adult patients. The effect of substrate rigidity on fibroblast-to-myofibroblast transdifferentiation (FMT) and the expression of COX-2, EP2, and EP4, with or without TGF-β1 stimulation, were investigated.

Results

The immunostaining of COX-2, EP2, and EP4 was substantially reduced in endometriotic lesions as lesions became more fibrotic. Both TGF-β1 stimulation and stiff substrates induced FMT and reduced the expression of COX-2, EP2, and EP4.

Conclusions

Since fibrosis is a common feature of endometriosis, our results thus cast doubts on the use of therapeutics that suppresses the PGE₂ signaling pathway, either by inhibiting COX-2 or EP2/EP4.

Identification of Key Differentially Methylated/Expressed Genes and Pathways for Ovarian Endometriosis by Bioinformatics Analysis

The goal of this study was to identify genes that were differentially methylated and differentially expressed and their related signaling pathways in ovarian endometriosis tissue. First, the DNA methylation and gene expression profiles in the endometrial tissue of patients with ovarian endometriosis were studied using Illumina 450K methylation microarray analysis and the GSE141549 gene expression dataset. Second, differentially methylated and differentially expressed genes, herein referred to as differentially methylated/expressed genes, were identified and protein-protein interaction networks and functional analysis of these genes were determined. Third, qPCR and immunohistochemistry of patient samples was used to confirm the differential expression of a subset of differentially methylated/expressed genes. Finally, the GSE7305 dataset was used confirm the expression profile of differentially methylated/expressed genes and to determine the potential usefulness of these genes for diagnosis of endometriosis. A total of 37 hypermethylated low-expression genes and 66 hypomethylated high-expression genes were identified in ovarian endometriosis patients. Protein-protein interaction and functional analysis highlighted 8 hypermethylated low-expression genes (KRT19, KRT8, ESR1, PRL, SFN, IL20RA, IL2RB, and PAX8) and 4 hypomethylated high-expression genes (CYP11A1, NR5A1, ME1, and GSTM1). Significantly, both of these gene sets had a diagnostic value for patients with ovarian endometriosis. Signaling pathways that were identified included JAK-STAT (involving IL20RA and IL2RB), prolactin (involving PRL and ESR1), Staphylococcus aureus infection (involving KRT19), viral protein interaction with cytokine and cytokine receptor (involving IL20RA and IL2RB), cytokine-cytokine receptor interaction (involving IL20RA and IL2RB), and drug metabolism-cytochrome P450 (involving GSTM1). The differentially methylated/expressed genes and enriched signaling pathways identified in this study are likely to be associated with the process of ovarian endometriosis.

The pro-inflammatory and anti-inflammatory role of hyaluronic acid in endometriosis

OBJECTIVE

Endometriosis is a bothersome disease affected women worldwide, the mechanism of disease development is still under investigation. Several inflammatory responses after clinical hyaluronic acid (HA) use were reported. Cyclooxygenase (COX)-2 mediated inflammation pathway is involved in the pathogenesis of endometriosis. Thus, we tried to investigate the inflammatory role of hyaluronic acid in endometriosis.

MATERIALS AND METHODS

Peritoneal fluid was collected in endometriosis and disease-free patients for the measurement of HA. Endometriotic stromal cells were treated with IL-1β and HA and expression of COX-2 was evaluated. Mice model of endometriosis was established and treated with fluid or gel form of HA. Endometriotic lesion size and weight were recorded and level of COX-2 was evaluated by immunohistochemistry staining.

RESULTS

The level of HA in the peritoneal fluid had no statistically significant difference between normal, early and advanced stage endometriosis patients. The overexpression of COX-2 protein was detected when treating endometriotic stromal cell with HA in the presence of IL-1β (P < 0.001). The endometriotic lesion size was reduced in mice model when treated with higher concentration gel form HA. It further showed less proportion of strong COX-2 expression compare of gel form HA to fluid form treatment in COX-2 expression score of endometriosis lesion.

CONCLUSION

Both proinflammatory evidence, elevated COX-2 expression, and anti-inflammatory result, reduced endometriosis lesion size and COX-2 expression score, were noted in our study after treating HA in in vivo and in vitro models. We hypothesized it is possible that HA may induce an acute proinflammatory response followed by chronic anti-inflammatory reaction in the formation of endometriosis.

Current Knowledge on Endometriosis Etiology: A Systematic Review of Literature

Objective

To review the mechanisms of endometriosis development, including those related to epigenetic mutations, cellular dysregulation, inflammatory processes, and oxidative stress.

Methods

A systematic literature review regarding current aspects of endometriosis etiology, genesis and development was performed using the PubMed, Google Scholar, and eLibrary databases. Keywords included endometriosis, etiology, development, genesis, associations and mechanisms. A multilingual search was performed.

Results

Several mechanisms underline the pathophysiological pathways for endometriosis development. Epigenetic mutations, external and internal influences, and chronic conditions have a significant impact on endometriosis development, survival and regulation. Several historically valid theories on endometriosis development were discussed, as well as updated findings.

Conclusion

Despite recent advances, fundamental problems in understanding endometriosis remain unresolved. The identification of unknown circulating epithelial progenitors or stem cells that are responsible for epithelial growth in both the endometrium and endometriotic foci seems to be the next step in solving these questions.

Effects of the FABP4 gene on steroid hormone secretion in goose ovarian granulosa cells

1. To investigate the physiological role of FABP4 in the goose ovary, this study determined the effects of overexpressing and siRNA interfering FABP4 on progesterone (P₄) and oestradiol (E₂) production in granulosa cells. Measurements were made by ELISA, real-time qRT-PCR and western blotting. 2. The concentrations of P₄ and E₂ in the FABP4 overexpression granulosa cells were increased compared to the control group (P > 0.05 for P₄; P < 0.05 for E₂). Likewise, the mRNA and protein expression levels of CYP11A1 and CYP19A1 were significantly higher than in the control group (P < 0.05 or P < 0.001). Conversely, the concentrations of P₄ and E₂ in the FABP4 silencing granulosa cells were significantly decreased compared with the control group (P < 0.001). Likewise, the mRNA and protein expression levels of CYP11A1 and CYP19A1 were significantly lower than in the control group (P < 0.001, or P < 0.01). 3. The study indicated that the FABP4 gene may regulate steroid hormone secretion and the expression of the steroidogenic genes in geese ovarian granulosa cells. These results support the possibility that the FABP4 gene mediates ovarian steroid hormone biosynthesis function and reproduction in geese.

Pathophysiological implications of hypoxia in human diseases

Oxygen is essentially required by most eukaryotic organisms as a scavenger to remove harmful electron and hydrogen ions or as a critical substrate to ensure the proper execution of enzymatic reactions. All nucleated cells can sense oxygen concentration and respond to reduced oxygen availability (hypoxia). When oxygen delivery is disrupted or reduced, the organisms will develop numerous adaptive mechanisms to facilitate cells survived in the hypoxic condition. Normally, such hypoxic response will cease when oxygen level is restored. However, the situation becomes complicated if hypoxic stress persists (chronic hypoxia) or cyclic normoxia-hypoxia phenomenon occurs (intermittent hypoxia). A series of chain reaction-like gene expression cascade, termed hypoxia-mediated gene regulatory network, will be initiated under such prolonged or intermittent hypoxic conditions and subsequently leads to alteration of cellular function and/or behaviors. As a result, irreversible processes occur that may cause physiological disorder or even pathological consequences. A growing body of evidence implicates that hypoxia plays critical roles in the pathogenesis of major causes of mortality including cancer, myocardial ischemia, metabolic diseases, and chronic heart and kidney diseases, and in reproductive diseases such as preeclampsia and endometriosis. This review article will summarize current understandings regarding the molecular mechanism of hypoxia in these common and important diseases.

Extra-adrenal glucocorticoid biosynthesis: implications for autoimmune and inflammatory disorders

Glucocorticoid synthesis is a complex, multistep process that starts with cholesterol being delivered to the inner membrane of mitochondria by StAR and StAR-related proteins. Here its side chain is cleaved by CYP11A1 producing pregnenolone. Pregnenolone is converted to cortisol by the enzymes 3-βHSD, CYP17A1, CYP21A2 and CYP11B1. Glucocorticoids play a critical role in the regulation of the immune system and exert their action through the glucocorticoid receptor (GR). Although corticosteroids are primarily produced in the adrenal gland, they can also be produced in a number of extra-adrenal tissue including the immune system, skin, brain, and intestine. Glucocorticoid production is regulated by ACTH, CRH, and cytokines such as IL-1, IL-6 and TNFα. The bioavailability of cortisol is also dependent on its interconversion to cortisone which is inactive, by 11βHSD1/2. Local and systemic glucocorticoid biosynthesis can be stimulated by ultraviolet B, explaining its immunosuppressive activity. In this review, we want to emphasize that dysregulation of extra-adrenal glucocorticoid production can play a key role in a variety of autoimmune diseases including multiple sclerosis (MS), lupus erythematosus (LE), rheumatoid arthritis (RA), and skin inflammatory disorders such as psoriasis and atopic dermatitis (AD). Further research on local glucocorticoid production and its bioavailability may open doors into new therapies for autoimmune diseases.

Endometriosis: The Role of Iron Overload and Ferroptosis

Iron is an essential element for cell survival, and iron deficiency is a known risk factor for many reproductive disorders. Paradoxically, such disorders are also seen more commonly under conditions of iron excess. Here, we focus on the problem of iron overload in women's health, using endometriosis as a model system. We propose (i) that a primary defect in endometriosis is abnormal eutopic endometrium characterized by resistance to ferroptosis, a process of iron-mediated non-apoptotic programmed cell death, which allows cells spread via retrograde menstruation to survive, implant, and establish endometriotic lesions within the abdominal cavity, and (ii) that dysregulated iron homeostasis may be critical to the subsequent pathophysiology of endometriotic lesions with localized iron overload and inflammation. We further investigate the association between endometriosis and hypercholesterolemia and suggest that an interaction between the mevalonate cholesterol biosynthetic pathway and ferroptosis signaling may provide a molecular basis to explain how it is that, in some women, endometrial tissues survive and thrive under ferroptotic pressure, colonize at ectopic sites, and expand into endometriotic lesions.

Platelets induce increased estrogen production through NF-κB and TGF-β1 signaling pathways in endometriotic stromal cells

Endometriosis is estrogen-dependent disorder. Two theories provide the explanations for the increased estrogen production. One is the feed-forward loop model linking inflammation and estrogen production. The more recent model evokes the tissue hypoxia resulting from endometrial debris detached and then regurgitated to the peritoneal cavity. Both models tacitly assume that everything occurs within the endometriotic stromal cells, seemingly without the need for exogenous factors. This study was undertaken to investigate as whether platelets may be responsible for local estrogen overproduction. We employed in vitro experimentation that evaluated the 17β-estradiol (E₂) levels in endometriotic stromal cells treated with activated platelets, and the genes and protein expression levels of StAR, HSD3B2, aromatase, and HSD17B1, as well as their upstream genes/proteins such as NF-κB, TGF-β1, HIF-1α, SF-1 and phosphorylated CREB. In addition, we conducted 2 animal experimentations using platelet depletion/infusion and also neutralization of NF-κB and TGF-β1, followed by immunohistochemistry analysis of involved in StAR, HSD3B2, aromatase, and HSD17B1, as well as SF-1 and p-CREB. We found that treatment of endometriotic stromal cells by activated platelets increase the E₂ production by 4.5 fold, and concomitant with increased gene and protein expression of StAR, HSD3B2, aromatase, and HSD17B1, the four genes/enzymes important to estrogen synthesis, along with their upstream genes HIF-1α, SF-1 and phosphorylated CREB. Moreover, platelets activate these genes through the activation of NF-κB and/or TGF-β1, and antagonism of either signaling pathway can abolish the induction of the 4 genes and thus increased estrogen production. The two animal experimentations confirmed these changes. Thus, platelets increase the E₂ production in endometriotic stromal cells through upregulation of StAR, HSD3B2, aromatase, and HSD17B1 via the activation of NF-κB and/or TGF-β1. These findings provide a yet another compelling piece of evidence that endometriotic lesions are indeed wounds undergoing repeated tissue injury and repair. They strongly indicate that non-hormonal therapeutics for endometriosis is theoretically viable, with anti-platelet therapy being one promising avenue.

Local estrogen formation and its regulation in endometriosis

BACKGROUND

It has been well established that endometriosis is an estrogen-dependent disease. Although the exact pathogenesis of the disease is still unclear, it is known to be characterized by estrogen-dependent growth and maintenance of the ectopic endometrium and increased local estrogen production.

METHODS

The authors reviewed studies on local estrogen production and estrogen activities mediated by estrogen receptors in endometriotic tissues.

MAIN FINDINGS

Aberrant expression of several enzymes in local endometriotic lesions contributed to the production and metabolism of estrogens. Aromatase was one of the key therapeutic targets for the regulation of local estrogen formation. Our findings suggest that PGC-1a, a transcriptional coactivator-modulating steroid hormone, regulates aromatase expression and activity. Estrogen activities mediated by different types of estrogen receptors abnormally elevated in local tissues could also be involved in the development of endometriosis. The authors demonstrated that the isoflavone aglycone, a partial agonist of the estrogen receptor, suppressed the formation of endometriotic lesions.

CONCLUSIONS

Local estrogen production and estrogen activity mediated by estrogen receptors are important potential therapeutic targets for endometriosis.

The Origin and Pathogenesis of Endometriosis

Recent molecular genetic findings on endometriosis and normal endometrium suggest a modified model in which circulating epithelial progenitor or stem cells intended to regenerate uterine endometrium after menstruation may become overreactive and trapped outside the uterus. These trapped epithelium-committed progenitor cells form nascent glands through clonal expansion and recruit polyclonal stromal cells, leading to the establishment of deep infiltrating endometriosis. Once formed, the ectopic tissue becomes subject to immune surveillance, resulting in chronic inflammation. The inflammatory response orchestrated by nuclear factor-κB signaling is exacerbated by aberrations in the estrogen receptor-β and progesterone receptor pathways, which are also affected by local inflammation, forming a dysregulated inflammation-hormonal loop. Glandular epithelium within endometriotic tissue harbors cancer-associated mutations that are frequently detected in endometriosis-related ovarian cancers. In this review, we summarize recent advances that have illuminated the origin and pathogenesis of endometriosis and have provided new avenues for research that promise to improve the early diagnosis and management of endometriosis.

Endometriosis

Pelvic endometriosis is a complex syndrome characterized by an estrogen-dependent chronic inflammatory process that affects primarily pelvic tissues, including the ovaries. It is caused when shed endometrial tissue travels retrograde into the lower abdominal cavity. Endometriosis is the most common cause of chronic pelvic pain in women and is associated with infertility. The underlying pathologic mechanisms in the intracavitary endometrium and extrauterine endometriotic tissue involve defectively programmed endometrial mesenchymal progenitor/stem cells. Although endometriotic stromal cells, which compose the bulk of endometriotic lesions, do not carry somatic mutations, they demonstrate specific epigenetic abnormalities that alter expression of key transcription factors. For example, GATA-binding factor-6 overexpression transforms an endometrial stromal cell to an endometriotic phenotype, and steroidogenic factor-1 overexpression causes excessive production of estrogen, which drives inflammation via pathologically high levels of estrogen receptor-β. Progesterone receptor deficiency causes progesterone resistance. Populations of endometrial and endometriotic epithelial cells also harbor multiple cancer driver mutations, such as KRAS, which may be associated with the establishment of pelvic endometriosis or ovarian cancer. It is not known how interactions between epigenomically defective stromal cells and the mutated genes in epithelial cells contribute to the pathogenesis of endometriosis. Endometriosis-associated pelvic pain is managed by suppression of ovulatory menses and estrogen production, cyclooxygenase inhibitors, and surgical removal of pelvic lesions, and in vitro fertilization is frequently used to overcome infertility. Although novel targeted treatments are becoming available, as endometriosis pathophysiology is better understood, preventive approaches such as long-term ovulation suppression may play a critical role in the future.

Endometriosis and ovarian cancer: Their association and relationship

Objectives

To study endometriosis-associated borderline or malignant ovarian epithelial tumors by analyzing their differential clinical features, as well as the histological pattern, survival and immunohistochemical data compared with those without associated endometriosis.

Study design

Setting: Hospital Marina Baixa and San Juan University Hospital, Alicante, Spain. This retrospective study included clinical and pathological data from 36 operated cases with endometriosis-associated ovarian epithelial tumors and 305 cases of ovarian epithelial tumors without endometriosis, including borderline and invasive tumors. We also studied hormonal receptors and p53 protein expression in 13 cases with endometriosis-associated endometrioid and clear cell tumors, and report two cases with histologically-confirmed previous endometriosis.

Results

Associated endometriosis was observed in 10.5% of patients with borderline or invasive ovarian epithelial tumor, 53% of those with endometrioid, and 22% with clear cell tumors. Patients with endometriosis-associated ovarian epithelial tumors were younger, had lower parity, were more frequently premenopausal, had a lower tumor stage or were borderline, and in general had better prognosis and longer survival, although they also more frequently had an associated endometrial carcinoma. Associated endometriosis and endometrioid tumors were generally estrogen-receptor positive, whereas they were negative in the clear cell tumor component. p53 protein positivity was generally observed in clear cell tumors and in associated endometriosis. Two reported cases with previous, known endometriosis were followed in their evolution to borderline endometrioid carcinoma and clear cell carcinoma, respectively.

Conclusions

Our results and review of the literature suggest that the association of ovarian epithelial tumors and endometriosis is a factor for good prognosis for ovarian cancer and that this association might correspond in many cases to an intermediate stage in the development of endometriosis to endometrioid, clear cell, or other invasive carcinomas.

Hypoxia: The force of endometriosis

AIM

Summarize recent findings of how hypoxia regulates numerous important processes to facilitate the implantation, proliferation and progression of ectopic endometriotic lesions.

METHODS

Most up-to-date evidences about how hypoxia contributes to the disease pathogenesis of endometriosis and potential therapeutic approaches were collected by conducting a comprehensive search of medical literature electronic databases. Quality of data was analyzed by experienced experts including gynecologist and basic scientists.

RESULTS

Uterus is a highly vascularized organ, which makes endometrial cells constantly expose to high concentration of oxygen. When endometrial tissues shed off from the eutopic uterus and retrograde to the peritoneal cavity, they face severe hypoxic stress. Even with successful implantation to ovaries or peritoneum, the hypoxic stress remains as a critical issue because endometrial cells are used to live in the well-oxygenated environment. Under the hypoxia condition, cells undergo epigenetic modulation and evolve several survival processes including steroidogenesis, angiogenesis, inflammation and metabolic switch. The complex gene regulatory network driven by hypoxia ensures endometriotic cells can survive under the hostile peritoneal microenvironment.

CONCLUSION

Hypoxia plays critical roles in promoting pathological processes to facilitate the development of endometriosis. Targeting hypoxia-mediated gene network represents an alternative approach for the treatment of endometriosis.

Intracrine Regulation of Estrogen and Other Sex Steroid Levels in Endometrium and Non-gynecological Tissues; Pathology, Physiology, and Drug Discovery

Our understanding of the intracrine (or local) regulation of estrogen and other steroid synthesis and degradation expanded in the last decades, also thanks to recent technological advances in chromatography mass-spectrometry. Estrogen responsive tissues and organs are not passive receivers of the pool of steroids present in the blood but they can actively modify the intra-tissue steroid concentrations. This allows fine-tuning the exposure of responsive tissues and organs to estrogens and other steroids in order to best respond to the physiological needs of each specific organ. Deviations in such intracrine control can lead to unbalanced steroid hormone exposure and disturbances. Through a systematic bibliographic search on the expression of the intracrine enzymes in various tissues, this review gives an up-to-date view of the intracrine estrogen metabolisms, and to a lesser extent that of progestogens and androgens, in the lower female genital tract, including the physiological control of endometrial functions, receptivity, menopausal status and related pathological conditions. An overview of the intracrine regulation in extra gynecological tissues such as the lungs, gastrointestinal tract, brain, colon and bone is given. Current therapeutic approaches aimed at interfering with these metabolisms and future perspectives are discussed.

Induction of Pyruvate Dehydrogenase Kinase 1 by Hypoxia Alters Cellular Metabolism and Inhibits Apoptosis in Endometriotic Stromal Cells

Endometriosis is a common gynecological disease, which is defined as the growth of endometrial tissues outside the uterine cavity. It often causes dysmenorrhea, dyspareunia, chronic pelvic pain, and infertility in reproductive-age women. However, the pathogenesis of endometriosis remains largely unclear. Since our previous study revealed that ectopic endometriotic stromal cells experience greater hypoxic stress than their eutopic counterparts, we aim to investigate whether the metabolic properties are changed in the ectopic endometriotic stromal cell when compared to its eutopic counterpart. Here, we found the expression of pyruvate dehydrogenase kinase 1 (PDK1), a critical enzyme in regulating glucose metabolism, was increased in ectopic stromal cells. Molecular characterization reveals that overexpression of PDK1 is induced by hypoxia through transcriptional regulation. Upregulation of PDK1 in ectopic endometriotic stromal cells was accompanied by increases in lactate production and oxygen consumption rate when compared to eutopic endometrial stromal cells. Furthermore, our data showed that inhibition of PDK1 activity by treatment with dichloroacetate inhibits the lactate production and oxygen consumption rate of ectopic stromal cells. In addition, hypoxia-induced PDK1 expression prevented cells from H₂O₂- and low nutrient-induced cell death. These data indicate that ectopic endometriotic cells may adapt to hypoxic microenvironment via upregulating PDK1 and reprogramming metabolism, which provides a survival advantage in the hostile peritoneal microenvironment.

The Endometriotic Tumor Microenvironment in Ovarian Cancer

Women with endometriosis are at increased risk of developing ovarian cancer, specifically ovarian endometrioid, low-grade serous, and clear-cell adenocarcinoma. An important clinical caveat to the association of endometriosis with ovarian cancer is the improved prognosis for women with endometriosis at time of ovarian cancer staging. Whether endometriosis-associated ovarian cancers develop from the molecular transformation of endometriosis or develop because of the endometriotic tumor microenvironment remain unknown. Additionally, how the presence of endometriosis improves prognosis is also undefined, but likely relies on the endometriotic microenvironment. The unique tumor microenvironment of endometriosis is composed of epithelial, stromal, and immune cells, which adapt to survive in hypoxic conditions with high levels of iron, estrogen, and inflammatory cytokines and chemokines. Understanding the unique molecular features of the endometriotic tumor microenvironment may lead to impactful precision therapies and/or modalities for prevention. A challenge to this important study is the rarity of well-characterized clinical samples and the limited model systems. In this review, we will describe the unique molecular features of endometriosis-associated ovarian cancers, the endometriotic tumor microenvironment, and available model systems for endometriosis-associated ovarian cancers. Continued research on these unique ovarian cancers may lead to improved prevention and treatment options.

SULFATION PATHWAYS: Contribution of intracrine oestrogens to the aetiology of endometriosis

Endometriosis is an incurable hormone-dependent inflammatory disease that causes chronic pelvic pain and infertility characterized by implantation and growth of endometrial tissue outside the uterine cavity. Symptoms have a major impact on the quality of life of patients resulting in socioeconomic, physical and psychological burdens. Although the immune system and environmental factors may play a role in the aetiology of endometriosis, oestrogen dependency is still considered a hallmark of the disorder. The impact of oestrogens such as oestrone and particularly, oestradiol, on the endometrium or endometriotic lesions may be mediated by steroids originating from ovarian steroidogenesis or local intra-tissue production (intracrinology) dependent upon the expression and activity of enzymes that regulate oestrogen biosynthesis and metabolism. Two key pathways have been implicated: while there is contradictory data on the participation of the aromatase enzyme (encoded by CYP19A1), there is increasing evidence that the steroid sulphatase pathway plays a role in both the aetiology and pathology of endometriosis. In this review, we consider the evidence related to the pathways leading to oestrogen accumulation in endometriotic lesions and how this might inform the development of new therapeutic strategies to treat endometriosis without causing the undesirable side effects of current regimes that suppress ovarian hormone production.

Progesterone Resistance in Endometriosis: an Acquired Property?

Endometriosis is the growth of endometrial tissue outside the uterus and is characterized by progesterone resistance and changes in global and progesterone target gene expression. However, the mechanism behind this and whether it is innate, acquired, or present in both the eutopic and ectopic tissue in not always clear. We find large-scale gene expression studies in eutopic tissue, indicative of progesterone resistance, are often contradictory, potentially due to the dynamic nature of this tissue, whereas suppressed progesterone receptor expression is supported in ectopic but not eutopic tissue. This suggests more studies are required in eutopic tissue particularly, and that potentially the suppressed progesterone receptor (PR) expression is a consequence of the pathogenic process and exposure to the peritoneal environment.

Notch-1 Signaling Activation and Progesterone Receptor Expression in Ectopic Lesions of Women With Endometriosis

Context

Progesterone (P) resistance is a hallmark of endometriosis, but the underlying mechanism(s) for loss of P sensitivity leading to lesion establishment remains poorly understood.

Objective

To evaluate the association between Notch-1 signaling activation and P resistance in the progression of endometriosis.

Design

Case control study; archived formalin-fixed, paraffin-embedded tissues.

Setting

University hospitals (United States, Taiwan).

Patients

Women with endometriosis; human endometrial stromal cell line (HESC).

Intervention

Eutopic endometria (EU) and ectopic lesions (ECs) were collected from surgically diagnosed patients. Archived tissue sections of EU and ECs were identified. HESCs were treated with N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT) and valproic acid (VPA) to, respectively, suppress and induce Notch-1 activation.

Outcome Measures

Tissues were analyzed for Notch Intra-Cellular Domain 1 (NICD1) and progesterone receptor (PGR) protein expression by immunohistochemistry and for transcript levels of NICD1 target genes HES1, PGR, and PGR-B by quantitative reverse transcription polymerase chain reaction. DAPT- or VPA-treated HESCs with and without P cotreatment were evaluated for cell numbers and for PGR, HES1, and PGR target gene DKK1 transcript levels.

Results

Nuclear-localized stromal NICD1 protein levels were inversely associated with those of total PGR in EU and ECs. Stromal ECs displayed higher HES1 and lower total PGR and PGR-B transcript levels than EU. In HESCs, DAPT reduction of NICD1 decreased cell numbers and increased PGR transcript and nuclear PGR protein levels and, with P cotreatment, maintained P sensitivity. Conversely, VPA induction of NICD1 decreased PGR transcript levels and, with P cotreatment, abrogated P-induced DKK1 and maintained HES1 transcript levels.

Conclusions

Aberrant Notch-1 activation is associated with decreased PGR that contributes to P resistance in endometriosis.

Androgens and endometrium: New insights and new targets

Androgens are synthesised in both the ovary and adrenals in women and play an important role in the regulation of female fertility, as well as in the aetiology of disorders such as polycystic ovarian syndrome, endometriosis and endometrial cancer. The endometrium is an androgen target tissue and the impact of AR-mediated effects has been studied using human endometrial tissue samples and rodent models. In this review we highlight recent evidence that endometrial androgen biosynthesis and intracrine action is important in preparation of a tissue microenvironment that can support implantation and establishment of pregnancy. The impact of androgens on endometrial cell proliferation, in repair of the endometrial wound at the time of menstruation and in endometrial disorders is discussed. Future directions for research focused on AR function as a therapeutic target are considered.

Dysfunctional signaling underlying endometriosis: current state of knowledge

Endometriosis is defined as the presence of endometrial tissue outside the uterine cavity. It affects approximately 5-10% of women of reproductive age. Endometriosis is associated with dysmenorrhea, dyspareunia and, often, severe pelvic pain. In addition to pain, women with endometriosis often experience infertility. Defining the molecular etiology of endometriosis is a significant challenge for improving the quality of women's lives. Unfortunately, the pathophysiology of endometriosis is not well understood. Here, we summarize the potential causative factors of endometriosis in the following three categories: (1) dysregulation of immune cells in the peritoneal fluid and endometriotic lesions; (2) alteration of apoptotic signaling in retrograde menstrual tissue and cytotoxic T cells involved in endometriosis progression and (3) dysregulation of oxidative stress. Determining the molecular etiology of these dysregulated cellular signaling pathways should provide crucial clues for understanding initiation and progression of endometriosis. Moreover, improved understanding should suggest new molecular therapeutic targets that could improve the specificity of endometriosis treatments and reduce the side effects associated with current approaches.

IL-1β Upregulates StAR and Progesterone Production Through the ERK1/2- and p38-Mediated CREB Signaling Pathways in Human Granulosa-Lutein Cells

The proinflammatory cytokine interleukin-1β (IL-1β) may be involved in several ovulation-associated events, such as protease synthesis, prostaglandin production, and steroidogenesis in granulosa cells. However, the exact effect of IL-1β on progesterone synthesis in granulosa cells and the underlying mechanism remain unclear. By using cultured granulosa-lutein cells collected from women undergoing in vitro fertilization or intracytoplasmic sperm injection, we found that IL-1β upregulated steroidogenic acute regulatory protein (StAR) expression and progesterone synthesis in granulosa-lutein cells, which was comparable with luteinizing hormone effect and could be abolished by an IL-1 receptor antagonist. Moreover, IL-1β activated the phosphorylation of cyclic adenosine monophosphate response element-binding protein (CREB), and knockdown of CREB attenuated the induction of StAR expression and progesterone synthesis by IL-1β in granulosa-lutein cells. Furthermore, IL-1β activated the extracellular signal-regulated kinase (ERK)1/2 and p38 pathways and inhibition of the ERK1/2 and p38 pathways attenuated the IL-1β-induced phosphorylation of CREB, StAR expression, and progesterone synthesis in granulosa-lutein cells. In conclusion, IL-1β could upregulate StAR expression and stimulate progesterone biosynthesis through increase in CREB phosphorylation via activating the ERK1/2 and p38 pathways in human granulosa-lutein cells.

Targeting hypoxia-mediated YAP1 nuclear translocation ameliorates pathogenesis of endometriosis without compromising maternal fertility

Endometriosis is a highly prevalent gynaecological disease that severely reduces women's health and quality of life. Ectopic endometriotic lesions have evolved mechanisms to survive in the hypoxic peritoneal microenvironment by regulating the expression of a significant subset of genes. However, the master regulator controlling these genes remains to be characterized. Herein, by using bioinformatics analysis and experimental verification, we identified yes-associated protein 1 (YAP1) as a master regulator of endometriosis. Nuclear localization and transcriptional activity of YAP1 were up-regulated by hypoxia via down-regulation of LATS1, a kinase that inactivates YAP1. Disruption of hypoxia-induced YAP1 signalling by siRNA knockdown or inhibitor treatment abolished critical biological processes involved in endometriosis development such as steroidogenesis, angiogenesis, inflammation, migration, innervation, and cell proliferation. Treatment with a YAP1 inhibitor caused the regression of endometriotic lesions without affecting maternal fertility or the growth rate of offspring in the mouse model of endometriosis. Taken together, we identify hypoxia/LATS1/YAP1 as a novel pathway for the pathogenesis of endometriosis and demonstrate that targeting YAP1 might be an alternative approach to treat endometriosis. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Epigenetic regulation of the pathological process in endometriosis

Background

Endometriosis is one of the most common gynecological diseases that greatly compromises the quality of life in affected individuals. A growing body of evidence shows that the remodeling of retrograde endometrial tissues to the ectopic endometriotic lesions involves multiple epigenetic alterations, such as DNA methylation, histone modification, and microRNA expression.

Methods

This article retrospectively reviewed the studies that were related to the epigenetic regulatory factors that contribute to the development and maintenance of endometriosis. A literature search was performed in order to collect scientific articles that were written in English by using the key words of "endometriosis," "epigenetics," "DNA methylation," "histone modification," and "microRNA."

Results

Epigenetic modifications, including DNA methylation, histone modification, and microRNA expression, are involved in the pathogenesis of endometriosis. These epigenetic players are regulated or tuned by microenvironmental cues, such as locally produced estradiol, proinflammatory cytokines, and hypoxic stress, and reciprocally regulate the process or response to those stimuli.

Conclusion

Understanding the molecular mechanisms that underlie these epigenetic regulatory processes would shed light on the etiology and/or progression of endometriosis and facilitate the development of novel therapeutic strategies.

Selective Estrogen-Receptor Modulators and Aromatase Inhibitors: Promising New Medical Therapies for Endometriosis?

Endometriosis is an estrogen-dependent disease and estrogen-related pathways are imbalanced in women with endometriosis. One of the key enzymes in estrogen synthesis is aromatase. Inhibiting this pathway at several points is a promising idea for the treatment of endometriosis. The third generation of aromatase inhibitors is becoming more potent in efficacy, with fewer side effects than previous generations, but cotreatment with other hormones is needed to inhibit ovarian stimulation. Other components that promote estrogen synthesis such as COX-2 can also be potentially targeted. Selective estrogen-receptor modulators could also be interesting in view of their tissue-specific effect. However, all these new drugs are still in an early phase of development. At present, it is too early to conclude that aromatase inhibitors, COX-2 inhibitors or selective estrogen-receptor modulators really present any added value compared with the existing drugs that can be used to achieve hormonal suppression in the medical treatment of endometriosis.

Estrogen receptor β regulates endometriotic cell survival through serum and glucocorticoid-regulated kinase activation

OBJECTIVE

To determine the expression and biological roles of serum and glucocorticoid-regulated kinase (SGK1) in tissues and cells from patients with endometriosis and from healthy control subjects.

DESIGN

Case-control.

SETTING

University research setting.

PATIENT(S)

Premenopausal women.

INTERVENTION(S)

Endometriotic tissues were obtained from women with ovarian endometriosis, and normal endometrial tissues were obtained from women undergoing hysterectomy for benign conditions.

MAIN OUTCOME MEASURE(S)

Expression levels of SGK1, the role of SGK1 in endometriosis pathology, and regulation of SGK1 by estrogen receptor (ER) β.

RESULT(S)

Transcript and protein levels of SGK1 were significantly higher in endometriotic tissues and cells compared with normal endometrium. SGK1 mRNA and protein levels were stimulated by E2, by the ERβ-selective agonist diarylpropionitrile, and by prostaglandin E2. SGK1 was transcriptionally regulated by ERβ based on small interfering RNA knockdown and chromatin immunoprecipitation of ERβ followed by quantitative polymerase chain reaction. SGK1 knockdown led to increased cleavage of poly(ADP-ribose) polymerase, and SGK1 activation was correlated with the phosphorylation of FOXO3a, a proapoptotic factor.

CONCLUSION(S)

ERβ leads to SGK1 overexpression in endometriosis, which contributes to the survival of endometriotic lesions through inhibition of apoptosis.

Role of the steroidogenic acute regulatory protein in health and disease

Steroid hormones are an important class of regulatory molecules that are synthesized in steroidogenic cells of the adrenal, ovary, testis, placenta, brain, and skin, and influence a spectrum of developmental and physiological processes. The steroidogenic acute regulatory protein (STAR) predominantly mediates the rate-limiting step in steroid biosynthesis, i.e., the transport of the substrate of all steroid hormones, cholesterol, from the outer to the inner mitochondrial membrane. At the inner membrane, cytochrome P450 cholesterol side chain cleavage enzyme cleaves the cholesterol side chain to form the first steroid, pregnenolone, which is converted by a series of enzymes to various steroid hormones in specific tissues. Both basic and clinical evidence have demonstrated the crucial involvement of the STAR protein in the regulation of steroid biosynthesis. Multiple levels of regulation impinge on STAR action. Recent findings demonstrate that hormone-sensitive lipase, through its action on the hydrolysis of cholesteryl esters, plays an important role in regulating STAR expression and steroidogenesis which involve the liver X receptor pathway. Activation of the latter influences macrophage cholesterol efflux that is a key process in the prevention of atherosclerotic cardiovascular disease. Appropriate regulation of steroid hormones is vital for proper functioning of many important biological activities, which are also paramount for geriatric populations to live longer and healthier. This review summarizes the current level of understanding on tissue-specific and hormone-induced regulation of STAR expression and steroidogenesis, and provides insights into a number of cholesterol and/or steroid coupled physiological and pathophysiological consequences.

MAP kinases and the inflammatory signaling cascade as targets for the treatment of endometriosis?

INTRODUCTION

The pathogenesis of endometriosis, a common benign disease, remains ill-defined, although it is clear that chronic inflammation plays a crucial role through mitogen-activated protein kinase (MAPK) signaling pathways. All current medical therapies for endometriosis are antigonadotropic, and therefore have a contraceptive effect. A concerted research effort is hence warranted with the aim of delivering novel therapeutics that reduces disease symptoms without blocking ovulation.

AREAS COVERED

The authors review the complex pathogenic mechanisms of chronic inflammation in endometriosis and their relationships with MAPK pathways. The authors conducted a literature search of descriptive and functional targeted validation of MAPK in the pathogenesis of endometriosis. The effects of MAPK inhibitors, which constitute potential agents for future treatments, are also described.

EXPERT OPINION

Preliminary studies have highlighted a crucial role for MAPK in driving endometriosis-related inflammation. MAPK inhibitors exhibit potent activity in terms of controlling growth of endometriosis lesions both in vitro and in animal models. As MAPK inhibitors are known to have a multitude of undesirable side effects, their use in humans has to be approached with great care. Indeed, use of these drugs would probably be limited to short exposures prior to surgery in cases involving the most severe disease phenotypes.

Transcriptome profiling identifies differentially expressed genes in Huoyan goose ovaries between the laying period and ceased period

The Huoyan goose is famous for its high egg-laying performance and is listed as a nationally protected domestic animal by the Chinese government. To elucidate the key regulatory genes involved in Huoyan goose egg laying, RNA from ovarian tissue during the ceased and laying periods was sequenced using the Illumina HiSeq 2000 sequencing platform. More than 12 million reads were produced in ceased and laying libraries that included 11,896,423 and 12,534,799 clean reads, respectively. More than 20% of the reads were matched to the reference genome, and 23% of the reads were matched to reference genes. Genes with a false discovery rate (FDR) ≤0.001 and log₂ratio ≧1 or ≤−1 were characterized as differentially expressed, and 344 up-regulated and 344 down-regulated genes were classified into functional categories. Twelve genes that are mainly involved in pathways for reproduction regulation, such as steroid hormone biosynthesis, GnRH signaling pathways, oocyte meiosis, progesterone-mediated oocyte maturation, steroid biosynthesis, calcium signaling pathways, and G-protein coupled receptor signaling pathway were selected for validation by a quantitative real-time polymerase chain reaction (qRT-PCR) analysis, the qRT-PCR results are consistent with the general expression patterns of those genes from the Illumina sequencing. These data provide comprehensive gene expression information at the transcriptional level that might increase our understanding of the Huoyan goose's reproductive biology.

Screening of a panel of steroid-related genes showed polymorphisms of aromatase genes confer susceptibility to advanced stage endometriosis in the Taiwanese Han population

OBJECTIVE

To establish a multilocus model for studying the effect of steroid-related genes on advanced stage endometriosis.

MATERIALS AND METHODS

A total of 121 patients with advanced stage endometriosis and 171 control women were included. Eighteen single-nucleotide polymorphisms (SNPs) from nine genes (HSD17B1, HSD17B2, HSD17B5, HSD17B6, CYP17, CYP19, ERα, ERβ, and PGR) were genotyped using the TaqMan assays. Logistic regression models were used to evaluate the genetic effects, with adjustment for other covariates.

RESULTS

Only the presence of the mutant CYP19 (aromatase gene) was associated with a significantly increased risk of endometriosis after adjusting for age, BMI, and parity (p = 0.002, OR = 2.69; 95% CI = 1.44-5.02). No association was ascertained between the other investigated SNPs and endometriosis.

CONCLUSION

Polymorphisms of the aromatase gene confer susceptibility to advanced stage endometriosis in the Taiwanese Han population.

Metformin inhibits StAR expression in human endometriotic stromal cells via AMPK-mediated disruption of CREB-CRTC2 complex formation

CONTEXT

Endometriosis is an estrogen-dependent disease affecting reproductive women. Metformin could have a therapeutic effect on endometriosis through regulation of local estrogen production.

OBJECTS

The aim of this study was to investigate the molecular and cellular mechanism by which metformin regulates StAR expression in human endometriotic stromal cells (ESCs).

METHODS

ESCs derived from ovarian endometriomas were cultured with metformin and prostaglandin E2 (PGE2). StAR mRNA was measured by quantitative PCR; pregnenolone, progesterone, and estrogen production were measured by ELISA kits; steroidogenic acute regulatory protein (StAR), AMP-activated protein kinase, cAMP response element binding protein (CREB), and CREB-regulated transcription coactivator 2 (CRTC2) protein expression were measured by Western blot assay; and CRTC2 translocation and its association with CREB were assessed by coimmunoprecipitation assay and CRTC2-CREB complex binding by a chromatin immunoprecipitation assay.

RESULTS

1) StAR mRNA levels in ESCs are 264 times higher than those in endometrial cells. 2) Metformin downregulates the StAR mRNA expression (maximum 31.7%) stimulated by PGE2 (2.4-fold) in ESCs. 3) PGE2 induces CRTC2 translocation and enhances its association with CREB to form a transcription complex that binds to the StAR promoter region. 4) Metformin prevents the nuclear translocation of CRTC2 by increasing AMP-activated protein kinase phosphorylation. This inhibits transcription of StAR by disrupting formation of the CREB-CRTC2 complex, involved in activation of the StAR promoter cAMP response element.

CONCLUSIONS

We have demonstrated a detailed mechanistic analysis of StAR expression regulated by metformin in ESCs. Our data highlight a role for CRTC2 in the mechanism by which metformin inhibits StAR expression.

ERβ- and prostaglandin E2-regulated pathways integrate cell proliferation via Ras-like and estrogen-regulated growth inhibitor in endometriosis

In endometriosis, stromal and epithelial cells from the endometrium form extrauterine lesions and persist in response to estrogen (E2) and prostaglandin E2 (PGE2). Stromal cells produce excessive quantities of estrogen and PGE2 in a feed-forward manner. However, it is unknown how estrogen stimulates cell proliferation and survival for the establishment and persistence of disease. Previous studies suggest that estrogen receptor-β (ERβ) is strikingly overexpressed in endometriotic stromal cells. Thus, we integrated genome-wide ERβ binding data from previously published studies in breast cells and gene expression profiles in human endometriosis and endometrial tissues (total sample number = 81) and identified Ras-like, estrogen-regulated, growth inhibitor (RERG) as an ERβ target. Estradiol potently induced RERG mRNA and protein levels in primary endometriotic stromal cells. Chromatin immunoprecipitation demonstrated E2-induced enrichment of ERβ at the RERG promoter region. PGE2 via protein kinase A phosphorylated RERG and enhanced the nuclear translocation of RERG. RERG induced the proliferation of primary endometriotic cells. Overall, we demonstrated that E2/ERβ and PGE2 integrate at RERG, leading to increased endometriotic cell proliferation and represents a novel candidate for therapeutic intervention.

Ser312Gly Polymorphism of the HSD17β1 Gene is not Associated with Endometriosis in Brazilian Patients

Purpose

The aim of this study was to determine whether a polymorphism of the HSD17β1 gene (rs605059), involved in estrogen synthesis, is associated with endometriosis in Brazilian patients.

Methods

A case-control study was conducted in 231 women. All patients in the case group had a histopathological diagnosis of endometriosis. Genomic DNA was genotyped by nested-PCR, followed by digestion of the PCR product with the enzyme BstUI.

Results

The frequencies of the genotypes detected in the case and control groups were 22.4% GG, 52.2% AG and 25.4% AA; and 31.3% GG, 49.3% AG and 19.4% AA, respectively, with no significant difference between groups. The prevalence of the G allele was 48.5% and 56% in the case and control groups, respectively. No significant difference in genotype or allele frequency was detected between the different stages of endometriosis (p>0.05).

Conclusions

The results suggested that the Ser312Gly polymorphism of the HSD17β1 gene is not associated with endometriosis in Brazilian patients.

Genome-wide DNA methylation analysis predicts an epigenetic switch for GATA factor expression in endometriosis

Endometriosis is a gynecological disease defined by the extrauterine growth of endometrial-like cells that cause chronic pain and infertility. The disease is limited to primates that exhibit spontaneous decidualization, and diseased cells are characterized by significant defects in the steroid-dependent genetic pathways that typify this process. Altered DNA methylation may underlie these defects, but few regions with differential methylation have been implicated in the disease. We mapped genome-wide differences in DNA methylation between healthy human endometrial and endometriotic stromal cells and correlated this with gene expression using an interaction analysis strategy. We identified 42,248 differentially methylated CpGs in endometriosis compared to healthy cells. These extensive differences were not unidirectional, but were focused intragenically and at sites distal to classic CpG islands where methylation status was typically negatively correlated with gene expression. Significant differences in methylation were mapped to 403 genes, which included a disproportionally large number of transcription factors. Furthermore, many of these genes are implicated in the pathology of endometriosis and decidualization. Our results tremendously improve the scope and resolution of differential methylation affecting the HOX gene clusters, nuclear receptor genes, and intriguingly the GATA family of transcription factors. Functional analysis of the GATA family revealed that GATA2 regulates key genes necessary for the hormone-driven differentiation of healthy stromal cells, but is hypermethylated and repressed in endometriotic cells. GATA6, which is hypomethylated and abundant in endometriotic cells, potently blocked hormone sensitivity, repressed GATA2, and induced markers of endometriosis when expressed in healthy endometrial cells. The unique epigenetic fingerprint in endometriosis suggests DNA methylation is an integral component of the disease, and identifies a novel role for the GATA family as key regulators of uterine physiology-aberrant DNA methylation in endometriotic cells correlates with a shift in GATA isoform expression that facilitates progesterone resistance and disease progression.

Suppression of COUP-TFII by proinflammatory cytokines contributes to the pathogenesis of endometriosis

CONTEXT

Endometriosis is one of the most common gynecological diseases in women with a prevalence rate of approximately 10%. Chronic pelvic inflammation has been observed in patients with endometriosis and is associated with disease severity. However, how pelvic inflammation promotes endometriosis progression remains unknown.

OBJECTIVE

The objective of the study was to investigate the regulatory network of proinflammatory cytokines in endometriosis progression.

DESIGN, SETTINGS, AND PATIENTS

Immunostaining of human endometrial (n = 21) and endometriotic (n = 36) sections, quantitative RT-PCR, Western blotting, chromatin immunoprecipitation, and luciferase reporter assays in primary culture human endometrial stromal cells were performed. Autologous transplantation of uterine endometrium from control chicken ovalbumin upstream promoter-transcription factor II [(COUP-TFII) flox/flox] and uterus-specific COUP-TFII knockout mice was performed.

RESULTS

Expression of COUP-TFII was significantly reduced in endometriotic stroma. Reduction of COUP-TFII in endometriotic stromal cells was mediated by proinflammatory cytokines including IL-1β, TNF-α, and TGF-β1 via a common effector, microRNA-302a. Treatment with these proinflammatory cytokines increased the expression of microRNA-302a, which targets the 3'untranslated region of COUP-TFII to cause its down-regulation. Intriguingly, down-regulation of COUP-TFII in endometrial stromal cells resulted in de-repression of cyclooxygenase-2 (COX-2). Further investigation demonstrated that COUP-TFII directly binds to COX-2 promoter to inhibit its transcription. Forced expression of COUP-TFII inhibited IL-1β-induced COX-2 up-regulation, whereas the knockdown of COUP-TFII augmented this effect.

CONCLUSION

Because overexpression of COX-2 has been demonstrated to be a master regulator in endometriosis progression, our data demonstrate the critical function of proinflammatory cytokines and the COUP-TFII regulatory gene network in the progression of endometriosis.

Expression and roles of steroidogenic acute regulatory (StAR) protein in 'non-classical', extra-adrenal and extra-gonadal cells and tissues

The activity of the steroidogenic acute regulatory (StAR) protein is indispensable and rate limiting for high output synthesis of steroid hormones in the adrenal cortex and the gonads, known as the 'classical' steroidogenic organs (StAR is not expressed in the human placenta). In addition, studies of recent years have shown that StAR is also expressed in many tissues that produce steroid hormones for local use, potentially conferring some functional advantage by acting via intracrine, autocrine or paracrine fashion. Others hypothesized that StAR might also function in non-steroidogenic roles in specific tissues. This review highlights the evidence for the presence of StAR in 17 extra-adrenal and extra-gonadal organs, cell types and malignancies. Provided is the physiological context and the rationale for searching for the presence of StAR in such cells. Since in many of the tissues the overall level of StAR is relatively low, we also reviewed the methods used for StAR detection. The gathered information suggests that a comprehensive understanding of StAR activity in 'non-classical' tissues will require the use of experimental approaches that are able to analyze StAR presence at single-cell resolution.

MicroRNA23a and microRNA23b deregulation derepresses SF-1 and upregulates estrogen signaling in ovarian endometriosis

CONTEXT

Steroidogenic factor (SF)-1 and its downstream target genes involved in estrogen signaling are aberrantly expressed in ovarian endometriosis.

OBJECTIVE

Our objective was to explore the microRNA-mediated mechanism controlling aberrant SF-1 expression in ovarian endometriosis.

DESIGN

Bioinformatics analysis predicted that microRNA23a and microRNA23b (miR23a/b) target the NR5A1 3'-untranslated region. We investigated the relative expression and spatial distribution of miR23a/b and analyzed the relationship between miR23a/b and SF-1 expression in endometriotic tissues.

SETTING

The study was conducted at the Department of Gynecology and Obstetrics, West China Second University Hospital of Sichuan University.

PATIENTS OR OTHER PARTICIPANTS

We enrolled 23 women with American Fertility Society stage III-IV ovarian endometriosis and 15 disease-free control subjects.

INTERVENTIONS

Quantitative real-time RT-PCR, in situ hybridization, cell culture, transfections, and luciferase reporter assays were used in this study.

MAIN OUTCOME MEASURES

The expression of miR23a/b and SF-1, CYP19A1, and StAR mRNAs; the relationships between miRNAs and SF-1 mRNA levels; and the effect of miR23a/b on SF-1 expression were measured in normal and eutopic endometrial stromal cells (ESCs) and 293T cells.

RESULTS

Both miR23a and miR23b were downregulated in ectopic and eutopic endometrium, compared with normal endometrium, and their expression was inversely correlated with NR5A1 mRNA levels. SF-1 expression was inhibited by miR23a/b overexpression in eutopic ESCs and upregulated by miR23a/b inhibition in normal ESCs.

CONCLUSIONS

MiR23a and miR23b are potential biomarkers of ovarian endometriosis. This study provides a novel approach for targeting the mechanisms controlling aberrant local estrogen biosynthesis in endometriosis.

Atypical Expression of COX-2, StAR, CYP19A1 and Apoptotic Regulators in CD90 Positive Endometrial Stromal Cells from Women with Endometriosis

Purpose

Endometriosis is an invasive gynecologic disease characterized by diminished apoptosis, sustained ectopic survival of dysfunctional endometrial cells and implantation of endometriotic lesions outside of the uterus. The purpose of this investigation was to determine the expression pattern of apoptotic and steroidogenic genes in the progenitor stem cell population of eutopic tissues from women with endometriosis and compare them to controls. The expression of these genes was determined in a subpopulation of endometrial cells that displayed CD90 positivity (CD+ve90) and colony forming capacity.

Methods

We obtained endometrial samples from women with or without endometriosis. Endometrial stromal cells (ESCs) were isolated and cultured for 15 days. Purified ESCs were sorted by using a multipotent mesenchymal stromal cell multi-color flow cytometry kit. Single cell cloning was performed by serial dilution in 96-micro well plates. Fifteen days later, colonies were identified (CFUs). The colonies were chosen and cultured. mRNA expression of apoptotic genes, mitogen activated kinase 14 (MAPK14), nuclear factor kappa B (NFkB), steroidogenic acute regulatory protein (StAR), aromatase (CYP19A1) and cyclo-oxygenase-2 (COX-2) were determined by qRT-PCR. Protein levels of StAR, CYP19A1 and COX-2 were determined by western blotting.

Results

A subset of stromal cells derived from women with endometriosis were isolated and identified as progenitor stem cells based on their CD90 positivity and colony forming ability. The cells displayed increased levels of MAPK14, NFkB, COX-2, StAR and CYP19A1 both at the mRNA and protein level compared to stromal cells derived from controls. Similarly, pro-apoptotic molecules such as Bax were decreased whereas anti-apoptotic molecules such as Bcl2 were decreased at the mRNA level compared to stromal cells derived from controls.

Conclusions

CD90+ve ESCs derived from women with endometriosis displayed markers suggesting stem cell-like properties and aberrant expression of apoptotic and steroidogenic enzymes which may contribute to sustained survival of these cells.

Suppression of annexin A2 by prostaglandin E₂ impairs phagocytic ability of peritoneal macrophages in women with endometriosis

STUDY QUESTION

Is annexin A2 involved in the reduced phagocytic ability of macrophages in endometriosis?

SUMMARY ANSWER

Data from women with endometriosis and a murine model of the disease show that expression of annexin A2 in peritoneal macrophages is inhibited by prostaglandin E2 (PGE2) and this impairs the phagocytic ability of macrophages.

WHAT IS ALREADY KNOWN

Endometriosis is a chronic inflammatory disease that recruits many immune cells, especially macrophages, to the peritoneal cavity. The phagocytic ability of peritoneal macrophages isolated from women with endometriosis is reduced.

STUDY DESIGN, SIZE, DURATION

A laboratory study. Thirty-five patients (20 with and 15 without endometriosis) of reproductive age with normal menstrual cycles were recruited.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Peritoneal macrophages isolated from women with or without endometriosis were cultured and treated with vehicle, PGE2 and different EP receptor agonists, and the expression of annexin A2 was quantified by RT-PCR and western blotting. Annexin A2 was knocked down (by small interfering RNA) in normal macrophages or overexpressed (by treatment with recombinant protein) in endometriotic macrophages and their phagocytic ability was measured by flow cytometry. Peritoneal macrophages were isolated from a mouse model of endometriosis and treated with PGE2 or cyclo-oxygenase (COX) inhibitors, and annexin A2 mRNA was quantified.

MAIN RESULTS AND THE ROLE OF CHANCE

Levels of annexin A2 were markedly reduced in peritoneal macrophages from women with endometriosis versus controls (mRNA: P < 0.01). The level of annexin A2 mRNA in the macrophages was reduced by PGE2 (P < 0.01/P < 0.05 in women without/with endometriosis versus control) via the EP2/EP4 receptor-dependent signaling pathway. Treatment with PGE2 or knockdown of annexin A2 inhibited the phagocytic ability of macrophages (P < 0.05 versus control), while treatment with annexin A2 recombinant protein enhanced phagocytosis. Autologous transplantation animal studies further confirmed that levels of annexin A2 in peritoneal macrophages were markedly reduced in mice treated with PGE2 (P < 0.01 versus control). In contrast, treatment with COX inhibitors to inhibit PGE2 production enhanced annexin A2 expression in peritoneal macrophages (P < 0.05 versus control).

LIMITATIONS, REASONS FOR CAUTION

We have provided no direct demonstration that phagocytic activity is indeed decreased in peritoneal cells from patients with endometriosis or that their endometriotic fluid contains increased amounts of PGE2 when compared with control subjects.

WIDER IMPLICATIONS OF THE FINDINGS

Inhibiting PGE2 signaling, in order to restore or enhance the phagocytic capability of macrophages, may represent a new direction of thinking in developing novel strategies against endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by grants from National Science Council of Taiwan, Republic of China (NSC97-2314-B-006-020-MY3) to M.-H.W. and (NSC98-2320-B-006-026-MY3) to S.-J.T., and grants from the Chang Gung Memorial Hospital, Taiwan, Republic of China (CMRPG891432 and CMRPG8A0531) to P.-C.C. None of the authors have any conflicts of interest.

The expression status of G protein-coupled receptor GPR30 is associated with the clinical characteristics of endometriosis

INTRODUCTION

GPR30 is a seven-transmembrane G protein-coupled estrogen receptor that regulates endometrial cellular responses to estrogen. GPR30 is often highly expressed in cancer cells from aggressive tumors. The aim of this study was to evaluate the expression patterns of GPR30 in endometriosis during medical treatment.

PATIENTS

A total of 38 females, 28 patients with endometriosis and 10 patients with leiomyoma who underwent laparoscopic surgery were included this study.

INTERVENTION

Eutopic endometrial tissue sampling from women without endometriosis and ectopic endometrial tissue sampling from women with endometriosis.

MAIN OUTCOME MEASURE

A quantitative real-time polymerase chain reaction analysis of the mRNA expression in eutopic and ectopic endometrial tissues with or without GnRH agonist treatment. The expression of GPR30 was confirmed by immunohistochemistry.

RESULTS

There was an increased level of GPR30 mRNA in eutopic endometrium during the proliferative phase, whereas higher expression was observed in the ectopic endometrium during the secretory phase. Increased GPR30 mRNA was observed in ectopic endometrium in comparison to eutopic endometrium. GnRH agonist treatment before laparoscopic surgery decreased GPR30 mRNA in ectopic endometrium. The immunohistochemical analysis also revealed that GPR30 was strongly expressed in epithelial cells in ectopic endometrium, whereas GnRH agonist treatment decreased the GPR30 expression.

CONCLUSION

High levels of GPR30 expression can play an important role in the progression of endometriosis.